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Study Name:
Orange River Integrated Water Resources Management Plan
Report Title:
Review of Groundwater Resources in the Orange River Catchment
Submitted By: WRP Consulting Engineers, Jeffares and Green, Sechaba Consulting, WCE Pty Ltd,
Water Surveys Botswana (Pty) Ltd
Authors:
A Viles
Date of Issue: August 2007
Distribution:
Botswana: DWA: 2 copies (Katai, Setloboko)
Lesotho: Commissioner of Water: 2 copies (Ramosoeu, Nthathakane)
Namibia: MAWRD: 2 copies (Amakali)
South Africa: DWAF: 2 copies (Pyke, van Niekerk)
GTZ: 2 copies (Vogel, Mpho)
Reports:
Review of Existing Infrastructure in the Orange River Catchment
Review of Surface Hydrology in the Orange River Catchment
Flood Management Evaluation of the Orange River
Review of Groundwater Resources in the Orange River Catchment
Environmental Considerations Pertaining to the Orange River
Summary of Water Requirements from the Orange River
Water Quality in the Orange River
Demographic and Economic Activity in the four Orange Basin States
Current Analytical Methods and Technical Capacity of the four Orange Basin States
Institutional Structures in the four Orange Basin States
Legislation and Legal Issues Surrounding the Orange River Catchment
Summary Report

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TABLE OF CONTENTS
1
INTRODUCTION ..................................................................................................................... 1
1.1 Background................................................................................................................... 1
1.2 SADC Protocol.............................................................................................................. 1
1.3 River Basin Commissions ............................................................................................ 2
1.4 Objectives and Methodology of ORASECOM Task 6 Groundwater Issues................ 2
2
BOTSWANA GROUNDWATER OVERVIEW ......................................................................... 4
2.1 Location and Access .................................................................................................... 4
2.2 Physiographic Setting : Geomorphology...................................................................... 4
2.3 Physiographic Setting : Climate ................................................................................... 7
2.4 Population ................................................................................................................... 11
2.5 Water Demand............................................................................................................ 14
2.6 Land Use, Infrastructure and Communications ......................................................... 20
2.7 Regional Geology ....................................................................................................... 22
2.8 Regional Geohydrology .............................................................................................. 28
2.9 Water Quality and Chemistry ..................................................................................... 32
2.10 Transboundary Groundwater Resources................................................................... 33
2.11 Aquifer Management Programmes ............................................................................ 35
2.12 Potential and Planned Groundwater Utilisation Projects in the Basin Area .............. 42
2.13 Reports and References............................................................................................. 43
3
NAMIBIA GROUNDWATER OVERVIEW............................................................................. 46
3.1 Historical Development of Water Affairs (DWA) in Namibia ...................................... 46
3.2 Climate........................................................................................................................ 47
3.3 Population Density...................................................................................................... 48
3.4 Economic Activities..................................................................................................... 49
3.5 Geology....................................................................................................................... 50
3.6 Geohydrology and Hydrology..................................................................................... 51
3.7 Groundwater and Surface Water Abstraction ............................................................ 54

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3.8 Water Quality .............................................................................................................. 58
3.9 Report and Information Listing ................................................................................... 59
4
LESOTHO GROUNDWATER OVERVIEW .......................................................................... 74
4.1 Introduction ................................................................................................................. 74
4.2 Geohydrology of Lesotho ........................................................................................... 77
4.3 Hydrogeological Data Availability and Procedures .................................................... 79
4.4 Groundwater Data Collection ..................................................................................... 83
4.5 Data Storage and Retrieval ........................................................................................ 84
4.6 Groundwater Resource Evaluation ............................................................................ 86
4.7 Groundwater Resource Assessment and Exploration ............................................... 89
4.8 General Recommendations for Lesotho Groundwater Issues .................................. 91
4.9 Available Groundwater Reports ................................................................................. 92
4.10 References and Additional Reports For Lesotho....................................................... 95
5
SOUTH AFRICA GROUNDWATER OVERVIEW................................................................. 99
5.1 Geology, Climate and Vegetation of the Orange River in South Africa................... 100
5.2 Groundwater Development Potential and Related Issues....................................... 101
5.3 Groundwater Sources within the Orange River Basin ............................................. 102
5.4 Implementation of Groundwater Resource Directed Measures .............................. 109
5.5 Geohydrological Data and Mapping (National and within the Basin) ...................... 118
5.6 Additional Relevant Groundwater Comments and Observations ............................ 120
5.7 Groundwater Monitoring ........................................................................................... 121
5.8 South African References ........................................................................................ 122
6
GROUNDWATER INFORMATION SYSTEMS FOR ORASECOM IWRMP...................... 124
7
CONCLUSIONS AND RECOMMENDATIONS .................................................................. 126
LIST OF FIGURES AND TABLES
Figure 2-1: Histogram of Automatic Rainfall Gauge at Khokhotsha Clinic................................... 10
Figure 2-2: Histogram of Automatic Rainfall Gauge at Werda Police Station.............................. 10
Table 2-3: Summary of Population Statistics Molopo River Basin Area ...................................... 11

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Table 2-4: Rural Village Water Demand Design Criteria .............................................................. 15
Table 2-5: Settlement Water Demand Forecasts (Nationwide).................................................... 16
Table 2-6: Percentage Water Demand Usage Nationwide .......................................................... 16
Table 2-7: Water Demands (all units x 106m3/annum) ................................................................. 17
Figure 2-3: National Water Demand and Usage for 1990 ............................................................ 17
Figure 2-4: Projected 2000 National Water Demand.................................................................... 18
Figure 2-5: Projected National Water Demand & Usage for Year 2020 ...................................... 18
Table 2-8: Water demands............................................................................................................ 19
Figure 2-6: Structural Geology of Botswana ................................................................................. 28
Table 2-9: Recharge Estimates for Basin Area from Previous Projects Undertaken................... 37
Table 2-10: Available Groundwater Reports for the Basin Study Area ........................................ 39
Figure 2-7: Land Information available at the Department of Surveys and Mapping .................. 42
Figure 3-1: Namibian Catchment of the Orange River with Sub-Catchments ............................. 46
Figure 3-2: Rainfall Distribution..................................................................................................... 48
Figure 3-3: Irrigation Below Naute Dam........................................................................................ 49
Figure 3-4: Namibian Geological Map .......................................................................................... 50
Figure 3-5: Approximate Position of Rainfall Stations .................................................................. 51
Figure 3-6: Gauging Stations in the Orange River Sub-Catchments ........................................... 52
Figure 3-7: Locations of water level monitoring points ................................................................. 53
Figure 3-8: Groundwater Control Areas in Namibia ..................................................................... 55
Table 3-1: Mean Annual Abstraction from Six Major Dams ......................................................... 56
Figure 3-9: Dams in the Namibian Sub-Catchments of the Orange River ................................... 56
Table 3-2: NamWater Schemes in the Sub-Catchments of the Orange River ............................ 57
Figure 3-10: TDS Values According to Namibian Water Quality Guidelines ............................... 58
Figure 3-11: Nitrate Levels According to Namibian Water Quality Guidelines ............................ 59
Figure 4-1: Locality map of Lesotho.............................................................................................. 74

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Table 4-1: Groundwater Reserves of Lesotho.............................................................................. 91
Table 5-1: Municipal groundwater use........................................................................................ 109
Figure 5-1: Pomfret ­ Vergelegen Dolomitic Aquifer showing sub-outcrop Geology ................ 112
Figure 5-2: Cross-section through the Tosca Dolomitic Aquifer................................................. 112
Figure 5-3: Groundwater level contours (mamsl) for 1977 (left) and 1990 (right)...................... 114
Figure 5-4: Areas of highest recharge ........................................................................................ 115
Figure 5-5: Groundwater level contours mamsl 1990 (left) and 2002 (right) ............................. 116
Figure 5-6: Difference in groundwater levels between 1990 and 2002. Blue circles represent
areas of intense pivot irrigation ............................................................................................ 116
Table 6-1: Features of some grohydrological / hydrological information systems ..................... 125
LIST OF ABBREVIATIONS
BCC
Borehole Completion Certificate
BHN
Basic Human Needs
BNWMP
Botswana National Water Master Plan
CMA
Catchment Management Agency
CMS
Catchment Management Strategy
CSIR
Council for Scientific and Industrial Research
CSO
Central Statistics Office
DGS
Department of Geological Survey
DRWS
Department of Rural Water Supply
DWA
Department of Water Affairs
DWAF
Department of Water Affairs and Forestry
EC
Electric Conductivity
FAO
Food and Agriculture Organisation
GDP
Gross Domestic Product
GMU
Groundwater Management Unit

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GPS
Global Positioning System
GOB
Government of Botswana
GRDM
Groundwater Resource Directed Measures
GRES
Groundwater Recharge Estimation Study
GRU
Groundwater Resource Unit
GWC
Groundwater Consultants BEEPEE
GWD
Groundwater Division
IAH
International Association of Hydrogeologists
ICM
Integrated Catchment Management
IGS
Institute for Groundwater Studies
ISARM
Internationally Shared Aquifer Resources Management Project
ITCZ
Inter Tropical Convergence Zone
IWRMP
Integrated Water Resource Management Plan
MAP
Mean Annual Precipitation
MAR
Mean Annual Runoff
NAMPAD
National Master Plan for Agricultural Development
NBA
National Borehole Archive
NGDB
National Groundwater Database
MAMSL
Metres Above Mean Sea Level
MCM/a
Million (Mega) cubic Metres per annum
MBGL
Metres Below Ground Level
NWA
National Water Act
NWQDB
National Water Quality Database
NWRS
National Water Resource Strategy
ORASECOM
Orange ­ Senqu River Commission
RDM
Resource Directed Measures

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RQO
Resource Quality Objective
RVWSDM
Rural Village Water Supply Design Manual
SWA
South West Africa
S
Storativity
SADC
Southern African Development Community
T
Transmissivity
TDS
Total Dissolved Solids
TMG
Table Mountain Group (Sandstone Aquifer)
VES
Vertical Electrical Soundings
WAB
Water Appointment Board
WARMS
Water Use Authorisation and Registration Management
WASA
Water and Sanitation Authority
WMA
Water Management Area
WMS
Water Management System
WRC
Water Research Commission

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Orange IWRMP
Task 6: Groundwater
1
INTRODUCTION
1.1
Background
The Orange River Basin extends into four countries; Republic of Botswana, The Kingdom
of Lesotho, the Republic of Namibia, and the Republic of South Africa. It includes the total
land area of Lesotho, most of the central part of South Africa and reaches to the southern
part of Botswana as well as draining most of the southern half of Namibia. The Orange-
Senqu River Commission (ORASECOM) came into existence on 3rd November 2000 by
agreement among the four basin member states in terms of the SADC Protocol on Shared
Watercourse Systems, with one of the primary aims being the integrated development and
management of the water resources of the Orange River to the mutual and equitable
benefit of all parties.
At the stage that ORASECOM was founded, extensive developments had already taken
place with respect to water resource infrastructure and utilisation of the resource. Amongst
others, large inter-basin transfer schemes have been developed which transfer water from
several other basins into the Orange River Basin as well as from the Orange River Basin
to other adjoining river basins. Plans have also been developed by some of the co-basin
countries with respect to possible further developments and aspects pertaining to the
future management and utilisation of the resources of the Orange River Basin. To facilitate
the integrated development and management of the resources of the Orange River jointly
by the four basin member countries, it is essential that common ground exist among the
basin countries with respect to the principles and objectives salient to the joint
management and that appropriate strategies and plans be developed to achieve this. A
key component and common reference base being the development of an Integrated
Water Resources Management Plan (IWRMP) for the Orange River Basin. This report
deals with the review of the groundwater resources and relevant groundwater issues as
they relate to the Orange River Basin.
1.2
SADC Protocol
The Protocol on Shared Watercourse Systems in the SADC Region contains amongst
others, the following fundamental principles :
· It recognises the relevant provisions of the United Nations Conference on
Environment
and
Development,
the
concepts
of
environmentally
sound
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Task 6: Groundwater
management, sustainable development and equitable utilisation of shared
watercourse systems in the SADC Region
· It is desirous of developing close co-operation for judicious and co-ordinated
utilisation of the shared watercourse systems
· The utilisation of shared watercourse systems within the SADC Region shall be
open to each riparian or basin State, in respect of the watercourse systems within
its territory and without prejudice to its sovereign rights, in accordance with the
principles in the Protocol
· Member States undertake to respect and apply the existing rules of general or
customary international law relating to the utilisation and management of the
resources of shared watercourse systems and, in particular, they respect and
abide by the principles of community of interests in the equitable utilisation of
those systems and related resources
· Member states lying within the basin of a shared watercourse system shall
maintain a proper balance between resource development for a higher standard
of living for their peoples and conservation and enhancement of the environment
to promote sustainable development
· Other Institutions for International Water Management in Southern Africa
1.3
River Basin Commissions
The role of the river basin commissions is to foster sustained dialogue between common
countries leading to cohesive and effective co-operative management and optimal
utilisation of shared water resources. They will provide focal points for the joint formulation
of development plans for the basin, co-ordination of joint basin studies, and collection and
sharing of information. The commissions are not water management institutions and the
responsibility for project implementation will normally remain with the local domestic
institutions.
1.4
Objectives and Methodology of ORASECOM Task 6 Groundwater Issues
The objective of the current phase (Phase One) is essentially a desktop study with
minimum, if any, fieldwork. During this phase, the focus will be on :
· To give an overview of the available data on groundwater
· To give an overview of the state of groundwater
· To assess the level of groundwater development
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· To assess the level of stress on the groundwater development
· To assess the capacity for further groundwater development
The review of groundwater resources involved the identification of information sources
within the four countries involved. Format of the information (hard copy or digital,
projection, file type, database package, etc.) as well as information status (complete, being
developed, planned), the availability thereof and when the information was captured
formed part of the investigation. In all cases it will be appreciated that the discussions and
observations presented are not intended to be conclusive, but rather to be indicative of the
efforts undertaken in this section of the study.
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2
BOTSWANA GROUNDWATER OVERVIEW
2.1
Location and Access
The Orange-Senqu River Basin in Botswana or the Molopo (as locally known) covers
approximately 71,000km2 of the southern section of the southern part of the country with
the Molopo River forming the southern boundary and the General Surface Water Divide of
southern Botswana forming the northern boundary of the basin. The international border
between Botswana and South Africa from Ramatlabama to Maiphitlwane forms the
eastern boundary of the basin while the Nossob River defines the southern part of the
western boundary of the basin. The international border between Botswana and Namibia
defines the northern part of the western boundary.
2.2
Physiographic Setting : Geomorphology
The Molopo River basin transects topographic landforms found in southern Botswana. In
the east around Ramatlabama and moving towards Pitshane-Molopo the topography is
reminiscent of a complex geological and structural history. The relief is gentle throughout
the area with the low north-south trending discontinuous Mosi Ridge. The topographic lows
are marked by the broad flat-bottomed dry valleys, which flatten out towards the west. The
drainage courses in the area are the Molopo River, Ramatlabama Spruit and the Matletse
Dry Valley. The Molopo River seldom has surface flow during the rainy season. Land
surface elevation decreases from 1200mamsl in the northeast to 1160mamsl in the
southwest in the Molopo River with the regional surface gradient trending southwest. The
outcrops of bedrock are restricted to the river valley and the Mosi Ridge.
Sands, loamy sands and occasional clays characterises the area and the vegetation is
fairly open grassland savannas with some patches of savannah woodlands and dense
stands of trees and shrouds close to the Molopo River valley.
The area between Mabule and Werda is generally flat with a slight increase in elevation to
the east. The physical landscape is generally flat to undulating, with topography sloping
generally southwards into fossil drainage of the Molopo River Valley. The general relief is
towards the south and southwest into the Molopo River Valley. Fossil valleys (palaeo-
channels) running from the east to the west are also visible with the Mosebele Fossil
valleys being the most prominent. The only other features are numerous pans and
remnant dunes. The soils are classified as sandy and sandy loams with a degree of clay
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content (luvic arenosol). The predominant vegetation is acacia thorn scrub whereas
grassland is generally associated with the pans and similar depressions.
Kalahari type environment is prominent west of Werda and tends to be poorly endowed
with surface water. The sandy soils that cover much of the Kalahari sandveld contribute to
poor surface water occurrence as a result of their poor retention abilities. However, the
Molopo River is occasionally active (ephemeral) and is the principal surface drainage
feature in the region. The Molopo River flows sporadically in its upper reaches past Werda
and beyond Makopong (sometimes reaching Draaihoek but rarely further). Intermittent
fluvial activity has left terraces and fluvial sediments along the river and river margins.
These features have been dated to the late Quaternary (DGS 2003 Werda Sekoma TGLP)
while the high terraces, beyond the confines of the present valley, are deemed to be older.
Flooding occurs infrequently and generally only in response to large-scale precipitation.
There are no river gauging stations.
Further to the west beyond Tsabong, the area has a gentle relief with pans and sand
dunes constituting major topographic features that are clearly visible on aerial photographs
and satellite images. There are no major surface drainage features in the area except for
the Molopo and Nossob fossil river systems marking the southern and western boundaries
of the basin respectively.
The southern part of the Gemsbok National Park covers most of the northwestern portion
of the Molopo River Basin. This is a flat and relatively featureless semi arid sand and dune
savannah region in which pans and associated dunes constitute the major topographic
features. Elevations are greatest in the northeast at approximately 1070mamsl with the
regional gradient being to the south and southwest i.e. towards the Molopo and Nossob
valleys that lie at elevations of around 890mamsl. Insufficient topographic data is available
to detail pans and the associated sand dunes. Pan floor levels are up to 15m below the
general land level, whilst dunes rise up to 30m above general land elevations. The dunes
are of two types viz. Barchan, crescent shaped dunes which are generally rare in the study
area and Seif dunes with a much more subtle relief which are often difficult to identify on
the ground. The Barchan dunes trend NNW whereas the Seif dunes trend in a NNE
direction.
Numerous pans are located in this part of the study area, ranging in size from the elongate
pans (5km in length by about 1km wide), to innumerable small `incipient" pan features of
less than 100m in diameter. The larger pans show a distinct trend being elongate in a
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north-south direction. The elongate pan direction generally parallels that of the sand
dunes.
Van Straten (1955) divided the Kalahari Pans into three categories :
· Grassed pans ­ pan sediments consist of dark sandy clays, which support a
dominantly grassy cover. Saline concentrations are low and calcrete generally not
well developed
· Ugrassed pans ­ pan sediments again consist of dark sandy clays, which support
sparse halophyllic (natural salt loving) vegetation
· Saline pans ­ pan sediments consist of saline and highly alkaline sandy clay with
no plant growth. The pans are commonly eroded into calcrete or a calcareous
sandstone deposit
All three types appear to be present within this part of the study area. The main phase of
pan deepening is likely to be an in-situ process. The present day climate gives rise to
sporadic pan flooding and evaporation in an environment in which chemical dissolution
and reprecipitation might be expected. Wind erosion (deflation) of the fine-grained clays,
salts and carbonates is likely to occur during each drying out phase.
The sand dunes are more prevalent in the western portion of Botswana and they form a
linear pattern in the northeasterly direction, indicating the predominant wind direction at the
time of formation. The pans in the area show a wide size range, distribution and shape.
Over 90% of the dunes in the region are linear, varying in height from 2m to greater than
30m above the interdunes, with some of the highest dunes occurring immediately adjacent
to the fossil valleys.
The Kalahari sands form poorly structured and infertile soils of low moisture retaining
capacity. As a result, there is no permanent surface drainage in the Kalahari and little or
no run-off. The soils of the southern Kalahari can be divided into red, pink and white sands
(DGS, 2002) with more than 90% sand fraction and fine soils like sandy clays, usually
found in riverbeds and pan floors. The red sand is most common and found on the plains
and dunes. The much less common pink sand (intermediate between red and white)
occurs in some dune slacks and around pans. It is richer in lime than the red sand. The
white sand is the least common type and is mainly found in riverbeds and pans. The soil is
richer in minerals than the other types.
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The southern part of the Gemsbok National Park is botanically classified as dune
savannah. Structurally, dune savannah is open savannah with scattered shrubs and trees.
In part the area is covered by Seif dunes where trees and dunes are commoner on the
dune slopes than on the crests or in the streets (areas) between. In those areas covered
by Barchan dunes the interdune streets are a much smaller component of the landscape
and woody species are much more prominent.
2.3
Physiographic Setting : Climate
The synoptic systems controlling Botswana's climate are dominated by a combination of
the seasonal movement of the large tropical and temperate zonal systems over Southern
Africa and their interaction with localised convective processes. North of 20° latitude,
primarily the Inter Tropical Convergence Zone (ITCZ) and the Zaire Air Boundary (ZAB)
complex influence the zonal system. The ITCZ attains its most southern position in
January when it approaches the northern border of Botswana. The ZAB lies over central
Zambia during the mid summer period when the low pressure also troughs into the
extreme south of the continent. The rainfall weakens south of latitude 20° as the drought
producing sub-tropical anticyclones (high pressure systems) become more dominant. This
is reflected in the more meridional alignment (airflow patterns) of rainfall isohyets across
South Africa, Botswana and Namibia with drier areas in the west and wetter areas to the
east. The latter reflects the differential in rates of subsidence of the air masses between
the east and west coasts of Southern Africa. Off the western coast, stronger subsidence
occurs as a result of the interaction between the almost stable Atlantic Ocean anticyclone
and cold waters of the Benguela Current. To the east, warm waters of the Agulhas
Current, more numerous rain producing disturbances and the marked eastward
displacement of the Indian Ocean anticyclone during summer result in weaker subsidence.
The climate in the basin area is semi arid with hot days and warm nights during the
summer months and warm days and cold nights during the winter months. Extreme diurnal
ranges are typical. Winter nights are very cold with the village of Tsabong averaging 72
days of ground frost annually, compared to 26 days in Gabarone.
2.3.1
Rainfall
The eastern part of the basin receives over 500mm mean annual rainfall. The annual
rainfall decreases towards the west where Bokspits receives below 300mm annually.
Rainfall is predominately convective and comprises instability showers and thunderstorms.
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This low rainfall is both spatially and temporally very variable and highly localised. Almost
all of the rainfall occurs during the summer period (October to April) with the winter period
accounting for only 5% of the annual total. The Department of Meteorological Services has
a synoptic weather office at Tsabong. However, rainfall figures are available from most of
the villages in the basin area and Table 2-1 provides some detailed information in this
regard.
Table 2-1: -Annual Rainfall Figures of Some Villages in the Study Area
Year SekomaMabutsaneKhakheaTsabongWerda
1981
N/a
91.2
N/a
327.7
278.9
1982
518
107.6
454.8
245.7
354.5
1983
294.2
119.5
294.1
366.7
N/a
1984
169.7
N/a
95.7
175.2
251.4
1985
272.8
130.1
136.7
144.4
206.9
1986
215.9
136.1
280.8
390.6
284
1987
N/a
N/a
260.3
262.6
279
1988
N/a
236.4
267.4
458.3
304.4
1989
N/a
N/a
400.4
226.6
290.7
1990
N/a
N/a
241.6
223.7
258.3
1991
695.8
116.3
306.5
389.3
629.5
1992
185.2
N/a
122.4
53.6
189.8
1993
263.8
239.7
269.3
252.7
291.5
1994
N/a
N/a
353.9
179
69.5
1995
N/a
N/a
N/a
230.4
297.7
1996
N/a
N/a
N/a
285.8
443
1997
319.8
N/a
524.5
331.9
N/a
1998
372.1
N/a
N/a
406.4
N/a
1999
N/a
N/a
N/a
327.3
N/a
2000
N/a
N/a
680.1
390
N/a
2001
N/a
N/a
609.3
508.4
N/a
2002
N/a
N/a
N/a
278
N/a
Average331
147
409
326
295
N/a - Not available or Incomplete Record, Source: Department of Meteorological Services, Gabarone
A list of rainfall measuring stations in the basin area is presented in Table 2-2.
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Task 6: Groundwater
Table 2-2: -Rainfall Gauging Stations in the Molopo River Basin
Molopo River Basin ­ Rainfall Gauging Stations
Arnadale Farm
Sedibeng
Bogogobo Primary School
Sekoma Primary School
Bokspits Primary School
Sekoma (He' s Farm)
Bray Border Post
Struizendam Primary School
Dalyspan
Tsabong Airport
Digawana Shop
Tsatsu Camp
Dipotsana Primary School
Twee Rivers Limpopo
Gakhibane Primary School
Werda Primary School
Gasita Primary School
Ditlharapeng
Gathwane Primary School
Papatlo Primary School
Goodhope Agric Research Station
Pelotshetlha Primary School
Hildavale Primary School
Phepheng Trading Store
Inverness
Phitshane Molopo Primary School
JM31 Farm
Pitsane BDF
Keng Primary School
Ramatlabama bull Stud
Khakhea Primary School
Ramatlabama Police Station
Khawa health Post
Lorolwana Primary School
Khisa Primary School
Mabule Primary School
Khuis Primary School
Makopong Primary School
Kincross
Masokwe
Kokotsha Primary School
Maubelo Primary School
Kolonkwaneng Primary School
Metlobo Primary School
Mogojwejwe
Middlepits Primary School
Mokatako
Mmathethe South
Mokhomma
Omaweneno Primary School
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Task 6: Groundwater
Rainfall at Kokotsha Clinic
50
45
40
35
)m
30
m(ll
25
a
inf
20
aR
15
10
5
0
6/6/02
7/4/02
8/1/02
8/8/02
9/5/02
1/2/03
5/30/02
6/13/02
6/20/02
6/27/02
7/11/02
7/18/02
7/25/02
8/15/02
8/22/02
8/29/02
9/12/02
9/19/02
9/26/02
10/3/02
11/7/02
12/5/02
10/10/02
10/17/02
10/24/02
10/31/02
11/14/02
11/21/02
11/28/02
12/12/02
12/19/02
12/26/02
Date
Figure 2-1: Histogram of Automatic Rainfall Gauge at Khokhotsha Clinic
Rainfall at Werda Police Station
50
45
40
35
)m
30
(m
25
infall
20
aR
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/0
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7/02
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0/02 27/0 /4/02 11/0 18/0 25/0
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7/17/ 7/
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Date
Figure 2-2: Histogram of Automatic Rainfall Gauge at Werda Police Station
2.3.2
Temperature
The warmest period at Tsabong is mid summer with a mean annual temperature of 34.8°C
and the coolest month is July with a mean minimum temperature of 4°C. Mean monthly
maximum temperature in the Tsabong area varies from 22.1°C in June to 34.8°C in
December. The mean monthly minimum temperatures vary from 4°C in July to 19.7°C in
January. Highest temperatures are recorded for November, December and January with
minimum temperatures occurring during June and July (occasionally sub zero).
13/11/2007
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Orange IWRMP
Task 6: Groundwater
2.4
Population
Some 2.8% of Botswana's population lives within the Molopo Basin area. Population
centres
include
Goodhope,
Gathwane,
Mogojogojowe,
Mmathethe,
Digawana,
Thareseleele, Ramatlabama, Mokatako, Phitshane-Molopo Mmakgori, Tshidilamolomo,
Mabule, Selokolela, Metlobo, Magoriapitse, Sekoma, Khakhea, Makopong, Khisa,
Omaweneno, Maleshe, Tsabong, Werda, Maralaleng, Struizendam, Rappelspan, Khuis,
Bogogobo, Middlepits, Khawa, Gakhibane and Bokspits. Southern Botswana hosts a very
low rural population density confined to the sparsely populated Kgalagadi District and the
moderately populated Southern District. The Botswana Central Statistic Office (CSO)
carries out a national population census every ten years. Population statistics derived from
the CSO 2001 census and the associated 2010 and 2020 population projections for the
Molopo River Basin are presented in Table 2-3.
Table 2-3: Summary of Population Statistics Molopo River Basin Area
POPULATION
LOCALITY/TOWN
2001
2010
2020
Goodhope
2934
3300
3414
Gathwane
922
927
928
Bogogobo
341
336
335
Sekoma
1033
1151
1188
Magoriapitse
969
1107
1151
Makopong
1501
1577
1600
Khakhea
2035
2096
2114
Omaweneno
1068
1127
1166
Khisa
423
455
464
Khonkhwa
473
490
495
Keng
931
1007
1031
Leporung
582
587
588
Werda,
1961
2108
2153
Tsabong
6591
7546
7848
Maleshe,
389
403
407
Maralaleng
487
567
625
Struizendam
313
318
335
Rappelspan
278
315
327
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Task 6: Groundwater
POPULATION
LOCALITY/TOWN
2001
2010
2020
Khuis
755
791
802
Khawa
517
538
544
Gakhibane
501
515
519
Bokspits
499
528
537
Thareseleele
767
778
781
Selokolela
1188
1296
1329
Metlobo
925
942
947
Mabule
1589
1631
1643
Tshidilamolomo
673
1783
1851
Mokatako
967
978
961
Mmakgori
742
834
863
Ramatlabama,
1174
1179
1180
Phitshane-Molopo
1569
1783
1851
Mogojogojowe
603
654
670
Kokotsha
1021
1053
1062
Kolonkwaneng
591
594
595
Vaalhoek
346
377
387
Dikhukhung
288
279
276
Bray
899
927
936
Sedibeng
616
701
728
Mmathethe
4415
4809
4930
Middlepits
657
707
722
Maubelo
453
491
516
Digawana
2675
2832
2879
Population in Molopo River Basin
47661
area
Total population in Botswana
1680863
Population outside Molopo River
1587038
Basin area
% Population in study area
2.8
Source ­ CSO 2001 Population Census
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Orange IWRMP
Task 6: Groundwater
2.4.1
Impact of HIV / AIDS Pandemic
Over the last ten years, the demographics of the country have changed significantly with
increasing numbers concentrated around the urban centres. Botswana's population is
becoming increasingly urbanised. The traditional way of life of people moving between the
village home, the fields, lands and cattle kraals is in decline with more people having
additional town domiciles. Both education and health care continue to be priority areas for
Botswana. The Government of Botswana (GOB) continues to improve and expand the
education system, consuming over a fourth of the 2000-2001 allocated expenditure
budget. The health care system has also received substantial inputs resulting in about
85% of the rural population living within 15km of a health facility. Public health expenditure
averaged 5-8% of the national budget between 1980 and 1999.
Between the 1974/75 and 1999/2000 financial years, the Gross Domestic Product (GDP)
of Botswana grew at an average rate of 9.1% increasing from (in Pula) P228 million to P26
billion in 1999/2000. This expansion was fuelled primarily in the structure of the economy
from agriculture and financial services to mining and public sector. Mining is now the
leading sector in the national economy, constituting more than 50% of Government
revenues and nearly 80% of foreign exchange earnings. Through diversification efforts by
the GOB and shifts in the global economy, the mining sector now represents about one
third of GDP.
The HIV / AIDS epidemic continues to deepen in Botswana. The overall, adjusted HIV
prevalence rate for pregnant women aged 15-49 has increased from 33.6% in 2000 to
36.2% in 2001. This increase is reflected across nearly all age groups. The trend of HIV
prevalence from 1993 to 2001 indicates that the prevalence rates for 2001 are double
those for 1993. Population growth structure continues to be altered as a result of the HIV
and AIDS epidemic. Mortality across age groups is on the rise in Botswana and life
expectancy has began a steady decline, from a GOB estimated high of about 66.2 years to
a projected low of 47.4 years (1999 & 2000 GOB Human Development Reports). It is
estimated that by the year 2010 life expectancy could reach a staggering low of 29 years.
Additionally, if nothing is done to halt the deepening of the epidemic, 30% of Botswana's
adult population could be lost over the next eight to ten years.
The structure of the population will shift to increasing numbers of both the very young and
very old. Household income levels are expected to drop at least 8% due to HIV and AIDS,
pushing the number of household below the poverty line up by around 5%. Ever
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Task 6: Groundwater
decreasing household resources may be increasingly channelled to medical and care
expenses, with less going to education and social amenities. The impact of HIV / AIDS is
keenly felt in the social sector in particular education and health. A high incidence of
morbidity and mortality among teachers reduces the number of classroom hours being
taught. At home, ill health among family reduces the time children spend at school or
attending to schoolwork. Similarly, the nation's health system is stretched to the limit as
the shear magnitude of the epidemic threatens to consume both health resources and
facilities. The massive burden of caring for and treating HIV and AIDS in Botswana will
increasingly limit the health care system to deliver even the most basic care to the rest of
the population.
The epidemic is having a catastrophic impact on the economy with an HIV prevalence of
some 36% among the workforce. The number and quality of people available to work will
decline over the next five to ten years. The loss of skills, institutional memory and
experience will create a vacuum in the labour market. Labour costs will rise along with
recruitment and retraining costs in order to meet the need of business and industry. Add to
that the costs of meeting expected medical and support costs may seriously reduce
corporate earnings, savings and investment levels, depressing the economy. It has been
estimated that the HIV / AIDS epidemic will cause a contraction of GDP by 1.5% over the
next 20-25 years resulting in an economy at least 31% smaller than would otherwise be
projected without the impact of the epidemic. The impact of the epidemic in respect of
water demands has not as yet been quantified by the GOB.
2.5
Water Demand
The economic success of the Republic of Botswana has translated into improved
infrastructure nationwide and increased household per capita income in rural villages. This
new buying power enables more households to have water connections. These
connections have proved to encourage high water consumption per capita as compared to
public standpipes. As such there is in creased demand for a reliable and convenient
potable water supply. Rural village water demand calculations are based on the DWA
(1989) Rural Village Water Supply Design Manual (RVWSDM). Rural water supply
schemes are designed for the water demands shown in following table :
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Task 6: Groundwater
Table 2-4: Rural Village Water Demand Design Criteria
Connection Type
% Served
Private connections
House connection
15%
Yard connection
20%
Public standpipe
65%
Source ­ DWA 1989 Rural Village Water Supply Demand Manual
The design criteria are:
· Standpipe (30 litres/day/person)
· Yard connection (60 litres/day/person)
· Household supply (150 litres/day/person)
The last decade has seen rapid infrastructural developments at rural village level, which
makes many of the RVWSDM water demand calculation formulae obsolete. There has
been a large increase in the number of housing developments at village level, which now
exceeds the 15% stated in the RVWSDM. Waterborne sewage systems are being
emplaced in the larger villages. Primary and junior Secondary Schools (JCSS) nationwide
are being equipped with waterborne sanitation facilities. The Ministry of Health is
establishing a network of primary hospitals located at sub-district HQ and major villages.
This combined with the many new developments (businesses, shopping malls etc.) in the
larger villages and the resulting urban life style (modern housing) of the population results
in a much higher water demand.
For major villages supplied from wellfields separate water demand studies are
implemented (as is the case in the Molopo River Basin). The studies are also based in the
consumption statistics given the RVWSDM and the Botswana National Water Master Plan
(BNWMP) planning documents.
Water demand forecasts contained in the BNWMP (1991) are presented below in Table
2-5. The BNWMP is currently being reviwed revision.
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Task 6: Groundwater
Table 2-5: Settlement Water Demand Forecasts (Nationwide)
Year
1990
2000
2010
2020
Population (103)
Urban Centres
262
437
647
949
Major Villages
294
431
597
816
Rural Villages
289
386
498
629
Minor Settlements
444
515
593
641
Domestic Demands (106m3)
Urban Centres
8.1
17.0
26.6
41.9
Major Villages
3.1
8.8
15.1
24.4
Rural Villages
1.8
3.2
5.1
6.8
Minor Settlements
2.4
2.8
3.3
3.5
Overall Demands (106m3)
Urban Centres
19.6
41.3
68.2
107.2
Major Villages
7.4
17.5
27.9
43.3
Rural Villages
3.6
6.3
9.5
12.6
Minor Settlements
3.3
3.8
4.4
4.7
Source ­ 1991 BNWMP
The 1991 BNWMP identifies five main water demand users : Domestic, Mines & Energy,
Livestock, Irrigation & Forestry and Wildlife. Percentage usage figures for the different
categories are presented in Table 2-6 and Figure 2-3 and Figure 2-4. Water demand
projections for the categories are presented in Table 2-7.
Table 2-6: Percentage Water Demand Usage Nationwide
Year
1990
2000
2010
2020
Demand Category
Settlements
28.6
38
45
51
Mines & energy
19.3
18.6
21.4
17.9
Livestock
30.7
22.7
14.3
14
Irrigation/forestry
16.4
17.4
16.9
15
Wildlife
5
3.3
2.4
2
Source BNWMP, 1991
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Orange IWRMP
Task 6: Groundwater
Table 2-7: Water Demands (all units x 106m3/annum)
Year
1990
2000
2010
2020
Demand Category
Settlements
33.7
68.8
109.9
167.8
Mines & energy
22.9
33.6
52.2
58.7
Livestock
36.5
41
34.8
46.7
Irrigation/forestry
19.5
31.6
41.3
49.8
Wildlife
6
6
6
6
Total
118.6
181
244.2
329
The domestic water demand for settlements increases with time to a projected total of 51%
of the total national water demand in 2020 as shown in Figure 2-5. In comparison the
percentage proportion of other users remains static or even declines with time (as in the
case of livestock).
N atio nal W ater Dem and 1990
5%
16%
29%
31%
19%
BN W N P,1991
S ettlem ents
Mines& energy
Liv estock
Irrigation/forestry
W ildlife
Figure 2-3: National Water Demand and Usage for 1990
These water demand figures have been calculated using a range of water consumption
between 15 - 130 litres/day/person.
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Orange IWRMP
Task 6: Groundwater
Projected National W ater Dem and 2000
3.3
17.4
Settlem ents
38
Mines& energy
Livestock
Irrigation/forestry
22.7
W ildlife
18.6
BNW MP,1991
Figure 2-4: Projected 2000 National Water Demand
Projected national water demand
180
160
140
120
Settlements
Mines& energy
100
Livestock
80
106m3
Irrigation/forestry
60
Wildlife
40
20
0
1990
2000
2010
2020
Figure 2-5: Projected National Water Demand & Usage for Year 2020
2.5.1
Water Demands for the Molopo (Orange) River Basin
Tsabong, Goodhope, Mmathethe, Digawana and Khakhea are considered major villages
in the Molopo River Basin. These villages thus have the highest water demand as
compared to other minor villages. The water demands of these villages are presented in
Table 2-8.
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Orange IWRMP
Task 6: Groundwater
Table 2-8: Water demands
POPULATION
Water Demand (m3/d)
Village
2001
2010
2020
2001
2010
2020
Goodhope
2934
3300
3414
220.05
247.50
256.05
Gathwane
922
927
928
69.15
69.53
69.60
Bogogobo
341
336
335
25.58
25.20
25.13
Sekoma
1033
1151
1188
77.48
86.33
89.10
Magoriapitse
969
1107
1151
72.68
83.03
86.33
Makopong
1501
1577
1600
112.58
118.28
120.00
Khakhea
2035
2096
2114
152.63
157.20
158.55
Omaweneno
1068
1127
1166
80.10
84.53
87.45
Khisa
423
455
464
31.73
34.13
34.80
Khonkhwa
473
490
495
35.48
36.75
37.13
Keng
931
1007
1031
69.83
75.53
77.33
Leporung
582
587
588
43.65
44.03
44.10
Werda,
1961
2108
2153
147.08
158.10
161.48
Tsabong
6591
7546
7848
494.33
565.95
588.60
Maleshe,
389
403
407
29.18
30.23
30.53
Maralaleng
487
567
625
36.53
42.53
46.88
Struizendam
313
318
335
23.48
23.85
25.13
Rappelspan
278
315
327
20.85
23.63
24.53
Khuis
755
791
802
56.63
59.33
60.15
Khawa,
517
538
544
38.78
40.35
40.80
Gakhibane
501
515
519
37.58
38.63
38.93
Bokspits
499
528
537
37.43
39.60
40.28
Thareseleele
767
778
781
57.53
58.35
58.58
Selokolela
1188
1296
1329
89.10
97.20
99.68
Metlobo
925
942
947
69.38
70.65
71.03
Mabule
1589
1631
1643
119.18
122.33
123.23
Tshidilamolomo
673
1783
1851
50.48
133.73
138.83
Mokatako
967
978
961
72.53
73.35
72.08
Mmakgori
742
834
863
55.65
62.55
64.73
Ramatlabama,
1174
1179
1180
88.05
88.43
88.50
PhitshaneMolopo
1569
1783
1851
117.68
133.73
138.83
Mogojogojo
603
654
670
45.23
49.05
50.25
Kokotsha
1021
1053
1062
76.58
78.98
79.65
Kolonkwaneng
591
594
595
44.33
44.55
44.63
Vaalhoek
346
377
387
25.95
28.28
29.03
Dikhukhung
288
279
276
21.60
20.93
20.70
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Orange IWRMP
Task 6: Groundwater
POPULATION
Water Demand (m3/d)
Village
2001
2010
2020
2001
2010
2020
Bray
899
927
936
67.43
69.53
70.20
Sedibeng
616
701
728
46.20
52.58
54.60
Mmathethe
4415
4809
4930
331.13
360.68
369.75
Middlepits
657
707
722
49.28
53.03
54.15
Maubelo
453
491
516
33.98
36.83
38.70
Digawana
2675
2832
2879
200.63
212.40
215.93
Totals
47661
52417
53678
3574.58
3931.28
4025.85
It has to be noted, however, that these demands are based on current life trends and
infrastructure. There are planned new developmental projects that will be highly water
intensive and it should be noted they have not been catered for in these water demands as
it remains currently unclear in the relevant policy documents how the provision of water for
these projects is going to be addressed.
2.6
Land Use, Infrastructure and Communications
It has only been recent that the GOB's Department of Town and Regional Planning have
made land use plans for the entire country. These plans updated and modernised the old
land tenure where land use policy was vague or in some cases nonexistent. The
infrastructural developments in the Molopo River Basin have been progressing very slowly
due to the low population and the simple vastness of the area.
2.6.1
Land Use
Due to the low rainfall charateristic of the Molopo River Basin, most of the area is devoted
to pastoral farming, both commercial pastoral farming or ranching and communal cattle
farming. Commercial ranches in the Molopo River Basin are located in the following areas:
Sekoma, Sekutlane, Middelputs, Makopong and Bokspits. The rest of the area is
characterised by clusters of boreholes and associated cattle posts. As one moves west
past Werda, the intensity of cattle posts and farms is reduced since adequate potable
water supplies are often difficult to locate and develop.
About 20% of the Molopo River Basin area forms part of the Mabuasehube Game reserve
and The Gemsbok Transfrontier Park. These areas have been reserved for wildlife
management and tourism activities. Commercial arable agriculture is active in the eastern
section of the basin in the Barolong farms and Mosi areas. Very large fields are cultivated
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Task 6: Groundwater
for rain fed crop production. Small-scale subsistence arable agriculture is practised in the
vicinity of most of the villages of the Molopo River Basin.
2.6.2
Communications
In an effort to foster expansion of economic activity and thus hopefully implementing
Botswana's National Socio-Economic Policy, the GOB developed a road network in the
country through a series of National Development Plans. The study area was no exception
to this initiative. In the east there is the Ramatlabama to Lobatse tarred road (a strategic
route) linking southeastern Botswana with neighbouring South Africa. Ramatlabama is
also connected to Mmathethe via Goodhope with another tarred road. The Sekoma to
Tsabong tarred road links the central Molopo River Basin with the eastern part of the
country via the Trans Kalahari Highway. In the extreme south there is a tarred road from
Goodhope to Tshidilamolomo linking most of the southern villages to the national road
network. A tarred road linking Tsabong and Bokspits is to be built to replace the current
gravel road (already commissioned?). The rest of the villages in the study area are linked
with gravel roads. Middelpits is linked to Struizendam via Bokspits with gravel, which runs
mostly along the Molopo River from Kolonkwaneng in the east. The road from Middelpits
to Khawa is a cleared sandy road and may be difficult to traverse at Matlalo cattle post
where it runs across cattle ranches and thus maintenance is kept at a minimum to reduce
pasture degradation.
There is a stretch of railroad in the east linking Ramatlabama and Lobatse. Due to the
well-established road network in the east, the railroad is used mainly for goods transport.
Several airstrips have been constructed in the study area; the most frequently used being
the Tsabong airstrip. These airstrips have been used for light aircraft transporting
government officials and the flying medical doctor service.
Major villages in the Molopo Basin are connected to both fixed landline telephone and
cellular phone service. Some villages in the extreme southwest like Bokspits do not have
both services and some rely on overlap of cellular phone services from neighbouring
South Africa.
2.6.3
Infrastructure
Both Tsabong and Goodhope have primary hospitals, which are used as referral services
for the sub-districts. All other villages have a clinic, health post or mobile stops for the very
small settlements and outlying cattle posts. All villages within the study area have a
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Task 6: Groundwater
primary school and some major villages have Community Junior Secondary Schools.
Water reticulation tends to be generally well established in most, if not all the villages.
There is usually a reservoir, which may be supplied from a wellfield or from a water
bowser. Water from the storage facility is gravity fed reticulation and access to the supply
would either be through centrally located public standpipes or yard connections.
Tsabong and Goodhope have planned waterborne sewage systems and this development
is anticipated to substantially increase the water demand for these villages. There are
plans to harness wastewater from the system for re-use in agriculture. This concept may
pose some cultural barriers, which would need to be addressed by the implementing
agents. The remainder of the study area generally has dry sewage systems (pit latrines).
There are exceptions as some schools have waterborne systems.
2.7
Regional Geology
Mapping and remote image sensing indicate that the Kalahari sand cover obscures most
of the hard rock geology. Aeolian sand deposits have produced a landscape characterised
by WNW to NW trending longitudinal sand dunes. Some rock exposures are found along
the Molopo River in Khuis, Werda and Phitshane Molopo. Outcrop of the pre-Kalahari
Group rocks is limited to the exposures of the Volop Group quartzites, with minor shales
and ironstones around Maralaleng, Omaweneno and Tsabong. The extent of the outcrop
areas can be readily mapped from aerial photography and have also been mapped in
detail by the GOB Geological Survey.
2.7.1
Basement Rocks
Most of the study area falls within an environment where bedrock is almost entirely
concealed by a veneer of Tertiary to Quaternary sediments known as the Kalahari Group
or Sequence. The bedrock geology is deduced from borehole and exploration drilling
records and from aeromagnetic surveys. As a result, there are many uncertainties
regarding the regional geology. A number of boreholes around the Tsabong area have
intersected granitic rocks, leuco-gabbros and gneissose-structured rocks. The full nature
of these rocks and their relationship to the other Supergroups remain yet to be determined.
The area around Werda lies in an area of sub-outcropping Proterozoic rocks of the Upper
Transvaal Supergroup and the somewhat younger Olifantshoek Formation (Waterberg
Group). In the north of the study area, the rocks fall within a basement high which projects
westwards into the western Kalahari and can be followed eastwards to the bedrock
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Task 6: Groundwater
outcrop zones of eastern Botswana. The basement high is generally devoid of Karoo
Supergroup cover and the Kalahari Group tends to be thin (generally less than 30m) but
thickens considerably in the direction of the Molopo River Basin in the south of the project
area. Both the Transvaal and Waterberg rocks consist of quartzites, sandstones, shales
and siltstones. The Upper Transvaal Supergroup includes some volcanic units, the most
common lithologies being andesite and felsite.
The Waterberg Supergroup rocks include red beds (the oldest rocks in Southern Africa)
that are absent from the Transvaal Supergroup. However, by no means all of the
Waterberg rocks are red and some Transvaal sandstones have a secondary red
colouration. It is acknowledged that distinguishing between Transvaal and Waterberg
clastic sediments is difficult, even in outcrop or where relatively long cored sections are
available. In percussion drilled boreholes, which tend to make up the vast majority of data
points within the study area, it is virtually impossible to assign rocks to one of these units
with any degree of certainty.
2.7.2
Olifantshoek Supergroup
This unit unconformably overlies the Griqualand West Supergroup, which is exposed to
the east in South Africa. Whereas the latter is an essentially marine succession of
carbonates, ferruginous sediments and argillites with minor arenites, the Olifantshoek
Supergroup is comprised mainly of coarse arenites including red beds. Quartzites of the
Volop Group outcrop near Tsabong and the hails between Omaweneno and Khisa.
The Olifantshoek rocks are tectonised by the Kheis Orogenic Belt that strikes north south
from the Orange River to the Okwa Valley in western Botswana. At Okwa, the strike
appears to swing to the northeast and it is possible that the Kheis Orogen is contiguous
with the Magondi Belt of Zimbabwe. The project area is on the eastern edge of the Kheis
Orogen and the rocks show various degrees of deformation. The exposures at Tsabong,
which are thought to belong to the Verwater Formation close to its transition to the white
ortho-quartzites of the Top Dog Formation, lack any penetrative fabric and form the
eastern limb of a synform which plunges gently to the south. The western limb of the
synform is exposed in a straightened zone north of Khweyane. The white, recrystallised
quartzites of the Omaweneno ­ Khisa area are tightly folded about a mainly north south
axis that can be mapped form aerial photography.
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Along the Molopo River from Kolonk in the east to Khuis in the west, the Volop Group
quartzites are seen to become progressively more deformed until at Khuis outcrops
display tight folding. Some thrust faults have been mapped in the area as well. Further
south towards the Korannaberg hills in South Africa, the Olifantshoek Supergroup rocks
display isoclinal recumbent folding and shallow angle north south striking thrust planes on
which movement has occurred from west to east. Almost certainly the thrust planes
continue north of Korannaberg into Botswana.
Faults oriented NE ­ SW passing to the north of Tsabong appear to have dextral strike slip
movements with the southern fault passing between the quartzite outcrops of Tsabong and
Maleshe. The northern fault is seen to displace magnetic bands within the Kheis zone. The
two parallel NW ­ SE faults south of the project area are considered to be a graben filled
with rocks of the Dwyka Group. A strong geophysical gravity gradient over the northern
fault indicates a change in the pre-Karoo lithologies across the fault, as a thickening of
Karoo rocks cannot itself explain the observed gravity anomaly.
The relationship between the Olifantshoek Supergroup and the Waterberg rocks of eastern
Botswana remains uncertain but it is likely they are chronostratigraphic equivalents. The
Olifantshoek rocks possibly represent a continental margin facies of the essentially intra-
continental Waterberg sediments.
2.7.3
Karoo Supergroup
Dwyka Group
The Dwyka Group unconformably overlies the Olifantshoek Supergroup rocks, which is the
lowermost group of the Karoo Supergroup. The Dwyka is a sequence of glaciogenic
sediments consisting of diamictites succeeded by fluvioglacial sandstones and argillites.
The basal tillites were deposited on a glaciated landscape, remnants of which can be seen
in the quartzite hills (well exposed in the Molopo Valley west of Khuis). The Dwyka Group
has been divided into a lower formation of essentially structureless diamictite ­ the
Malogong Formation ­ and an upper heterolithic formation of diamictites, shales and
sandstones of the Khuis Formation. The area of Dwyka east of Tsabong appears to be
contiguous with a large NE ­ SW palaeovalley infilled with Dwyka rocks. A NW ­ SE
trending trench to the south Logaganeng is infilled by Dwyka sediments.
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Ecca Group
The Ecca group is divided into two formations. These are the lower Kobe Formation of
slightly carbonaceous mudstone followed by the Otshe Formation of cyclical mudstones,
siltstones, sandstones and coals. The Otshe Formation is the equivalent of the Auob
Sandstone of Namibia and the Middle Ecca and Mea Arkose of eastern Botswana. The
underlying Kobe Formation is mainly a black mudstone that is easily pulled apart by hand.
Thin sand lenses are seen with sandstone bands becoming more frequent towards the
bottom of the unit. At the base of the Kobe Formation, overlying the Dwyka rocks is a 2m
unit of pink to light brown, coarse well sorted sandstone with a 2cm conglomerate at its
base. This sandstone is classified as the Nossob Member of the Formation and is believed
to correlate with the Nossob Sandstone of Namibia.
Beaufort Group
The Beaufort Group is composed of greenish-red, non-carbonaceous, shales belonging to
the Kwetla Formation.
2.7.4
Post Karoo Dolerites
Post Karoo dolerite dykes and sills are common in the southern Kgalagadi. Further west
within the Karoo basin, a number of sills are emplaced into the Karoo succession. The
stratigraphic level of the Ecca-Beaufort Group contact appears to be favoured for sill
intrusion. The dolerites are correlated with the Jurassic Drankensberg basalts. The
presence of the dolerite sills has been confirmed by drilling logs from boreholes and
exploration holes. The age of the sills are unknown as they occur at various stratigraphic
levels but are generally thought to be post-Karoo age. Other intrusives are norites and
ultrabasics of the Molopo Farms Complex as well as Archean granites and felsites.
2.7.5
Post Karoo Kimberlites
A major cluster of kimberlite intrusives consisting of at least 60 separate intrusions lies to
the north, south and west of Tsabong. All of the intrusions are covered with Kalahari Group
sediments but their presence was revealed by the widespread occurrence of widespread
kimberlite indicator minerals in the soils. This was recognised by De Beers Prospecting
circa 1970 but the discoveries were made later by Falconbridge Explorations Botswana
between 1978 and 1981 using low level aeromagnetic surveys. Although diamonds have
been found, none of the Tsabong kimberlites carries sufficient grade to be exploited. There
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are clear signs of structural control in the emplacement of some of Tsabong Kimberlites.
The kimberlites are believed to be all of Cretaceous age.
2.7.6
Kalahari Group
The Kalahari Group is a unit of continental sediments of Palaeocene to Recent Age with a
complex history in which the stratigraphy and age of the deposits are not well understood.
Low fossil content, limited exposure, the ubiquitous cover of surficial Aeolian sand and a
limited understanding of the extensive duricrusts make reconstruction of Kalahari
stratigraphy difficult. It is evident, however, that recurring cycles of erosion and deposition
have re-worked the same sediment. It is also difficult to separate primary depositional
effects from secondary modifying processes.
Broadly, the Kalahari Group consists of a layer of Aeolian sand up to 20m thick that may
display relict dune structures, mainly Barchans. At the present time, the sand is fixed by
vegetation and the dunes are fossil. The sand is generally underlain by a duricrust of
silcrete and calcrete that must represent an unconformity within the succession. Poorly
consolidated sandstones that are often calcareous underlie the duricrust. Where a full
succession is present, red marls and a basal clayey gravel of undoubted fluvial origin
underlie the sandstones. The thickness of the Kalahari succession is largely a function of
pre-Kalahari Group topography, with the gravels being largely confined to palaeovalleys
and channels.
The palaeo-drainage system represents a post Waterberg elongate southwest trending
basin infilled with Karoo Supergroup, Dwyka Group and tillites. During the post-Karoo
period, a drainage system was cut into the soft Dwyka sediments that in turn were infilled
by Tertiary Kalahari Group sediments.
The maximum known thickness of this unit is 120m (north of McCarthy's Rust) but in
excess of 220m is proven in the Bray area and in adjoining Northern Cape Province. The
surface Aeolian sands, named the Gordonia Sand Formation, are up to 20m thick and are
underlain by a duricrust horizon of silcrete and calcrete. Fine-grained sandstones with a
carbonate or silica cement matrix and containing lenses of clayey material underlie the
cretes. The Budin Clay Formation (a red clay) is restricted to valleys or depressions in the
pre-Kalahari surface and may be fluvial or lacustrine in origin. It grades into a basal gravel
(Wessels Gravel Formation) that is a coarse alluvial deposit restricted mainly to
palaeovalleys.
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The thickness and distribution of the Kalahari Group is largely a function of the pre-
Kalahari topography. Some of the buried channels, in which the clays and gravels were
deposited, follow the approximate alignment of Palaeozoic pre-Dwyka valleys. There may
thus be a local correspondence between the distribution of the thickest developments of
the Kalahari Group and Dwyka group, in particular the Malogong Formation. This may be
the case for the pre-Kalahari valley that appears to trend NW-SE to the northeast of
Tsabong. The Kalahari sandstones (Eden Formation) have a much wider distribution than
the clays and gravels and may have been in part deposited in a braided river system.
In Quaternary times, major rivers such as the Molopo and Kuruman have incised the
Kalahari Group, which may now be exposed in cliffs overlooking the valleys. This is well
seen in the Molopo Valley around Middelpits. Recent alluvial gravels are found in the
present and sometimes earlier courses of these rivers but are now often buried by wind
blown sands. Gravels, possibly deposited on old terraces of the Molopo River, cover an
extensive area north of Middelpits and recent gravels are known in the present bed of the
Molopo at McCarthy's Rust.
2.7.7
Structure
The Molopo River Basin lies between the Kaapvaal Craton in the east until a few
kilometres west of Tsabong. At Tsabong, early Proterozoic rocks of the Kheis and
Mangodi Orogenic Belts are encountered. In the west there is the Nossob-Ncojane Basin
of the Damara Orogenic Belt. Most of the study area has been tectonically stable since
the end of the Achaean, approximately 2700 million years ago. Kheis Orogenic Belt
occurred approximately 1900My the core of which lies to the west along the margin of the
Kaapvaal Craton, as conventionally defined. Two major igneous complexes have been
intruded into Kaapvaal Craton namely the Molopo Farms Complex and the Gabarone
Granite.
Lack of exposure in the study area limits any detailed structural analysis.
However evidence from outside the study area shows that gentle to moderate bi-
directional folding (E-W and NNW-SSE), associated with faulting (NW-SE), and took place
between the deposition of the Transvaal and Waterberg Supergroups. It is clear that the
rocks are extensively faulted, and are most probably within the area affected by the Kheis
Orogenesis. It is likely that the basement rocks of the project area are at least affected by
thrust faults with west to east translation, and recent high quality aeromagnetic data points
to ductile deformation. There is no evidence for post-Waterberg folding in the area,
therefore the Waterberg deposition was almost certainly controlled by pre-Waterberg
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folding and faulting. Most faults are inferred from geophysical surveys, LandSat and aerial
images. Such interpretation suggests NE-SW is predominant.
Post Waterberg faulting seems mainly to be parallel to the dolerite dykes in the area,
which trend WNW, NW or NNW. The geological structure of Botswana is contained in
Figure 2-6.
Figure 2-6: Structural Geology of Botswana
2.8
Regional Geohydrology
The Molopo River Basin encompasses all of the known aquifer units in Botswana. These
include :
· Basement Aquifers
· Transvaal and Waterberg Aquifers
· Upper Proterozoic Aquifers
· Karoo Aquifers
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· Kalahari Group Aquifers
· Sand River Alluvial Aquifers
The Botswana National Water Master Plan sub-divided the various aquifers in Botswana
into the following four categories :
· Fractured porous ­ Dual porosity system whereby water is released from a
porous matrix via a series of transmissive interconnected fractures
· Fractured ­ Aquifer whose material has limited porosity due to the rocks' solid
fracture or to subsequent metamorphic changes. In this case fracturing, jointing
and weathering provide the storage and transmissive properties of the aquifer
· Porous ­ Aquifers that store and transmit water via the interstitial pore space in
the sedimentary formation
· Karstic Fractured ­ Aquifers in carbonate rocks where solution-weathering joints,
fractures and bedding have enhanced the water-bearing properties of the rock.
The Molopo River Basin area within Botswana contains all four of the above mentioned
aquifer types. These are :
· The fractured porous type, represented by the Karoo sandstones, comprise 37%
and are the most common but generally nearly always saline
· The porous aquifers, represented by alluvial and Kalahari bed aquifers, comprise
35% are generally saline or low yielding and occasionally fresh
· The fractured aquifer, which includes the Archaean Basement and Proterozoic
aquifers and Karoo Basalts, comprise 27%
· The Karstic fractured aquifers, which are represented by the Transvaal dolomite
units, comprise only around 1%
The Hydrogeological Reconnaissance Map published by the Department of Geological
Survey (DGS) indicates the groundwater resource potential of the study area tends vary
from fair in the northwest to poor in the southeastern section and the area around Tsabong
is classified as fair to good. Relevant maps show that the areas of fair to good
groundwater potential coincide with areas of quartzitic outcrop.
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2.8.1
Basement Aquifers
Generally there are poor prospects of securing groundwater in the Proterozoic rocks of the
study area. Groundwater occurrence in these rocks can be wholly attributed to secondary
porosity (water contained in fractures and fissures). As such, the resource is controlled by
the size of the fractures and their relative interconnectivity. The most significant aquifer is
located at Sedibeng where ten boreholes have been drilled with average yields per
borehole of around 5m3/hr. These favourable water-bearing lithologies are restricted
mainly to the east of the study area and are classified by the National Hydrogeological
Reconnaissance Maps as having fair groundwater potential.
2.8.2
Transvaal and Waterberg Aquifers (Olifantshoek Sequence)
Several boreholes were drilled in the areas between Khuis and Kolonkwaneng for village
water supply to Khuis, Middelpits, Bogogobo and Kolonkwaneng villages. The quartzites
generally outcrop in the area but can be overlain by Kalahari Beds and river alluvials,
which can reach a thickness of up 23m. Water strikes in the fractured quartzites range
from as shallow as 10m to as deep as 200m. Borehole yields tend to be highly variable
and range from dry to 40m3/hr. The static water levels of boreholes range from 5m to
100m indicating that groundwater in the fractures occurs under unconfined to semi-
unconfined
conditions
(with
partial
compartmentalisation).
In
Bogogobo,
artesian
conditions were reported at Borehole 5898 indicating confinement in the fractured
quartzites. Tsabong and Goodhope are the only major supply wellfields within the Molopo
River Basin catchment exploiting the Transvaal and Waterberg aquifers.
The Olifantshoek Sequence is dry in the Middelpits area and according to DGS Botswana,
the quartzite north of Middelpits may be productive and further groundwater exploration
and development programmes are recommended to fully define and delineate the
groundwater potential. The GOB, in the absence of alternatives, knowingly mine (wellfield
annual abstraction exceeds annual recharge) the groundwater resources from the aquifers
at Tsabong (Waterberg Group). Groundwater has long residence times in this area and is
classified as fossil (old waters). Long residence times suggest areas of low recharge
potential.
2.8.3
Karoo Aquifers
The Dwyka Formation does not constitute an important aquifer in the study area as
suggested by the results from boreholes drilled near Gakhibane. These boreholes were
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dry (no water strike recorded). In borehole 9423, minor seepage accumulation was noted
after drilling. A representative water sample was collected and subsequent water
chemistry results indicated highly saline water with an associated Total Dissolved Solids
(TDS) of some 7170mg/l. Known borehole yields in this aquifer are generally considered to
be low, showing little confining head and poor quality water.
The Ecca Group sediments cover more than 40% of the study area and hence vast
majority of boreholes have been drilled in these sediments. The Ecca sediments occur
under varying thickness of Kalahari beds ranging from 10m to 55m. The Otshe sandstone
of the Ecca Group forms an important aquifer in the study area with localised areas of
potable groundwater. It consists of a complex succession of fluvial and deltaic sediments.
The sediments consist of multiple interbedded layers coarse-grained sandstone, shales,
mudstone, carbonaceous shale and poor coal. Argillaceous units within the formation
confine the individual water-bearing sandstone units.
The Otshe sandstone generally provides sufficient yields (2-3m3/hr) for livestock watering
in both confined and unconfined conditions. The confined sandstone generally yield very
saline water while semi-confined sandstone yield usable brackish water and in some areas
the confined Otshe sandstone aquifer contains fluids too saline for any agricultural use.
Depths to first water strike in the Ecca sediments are highly variable and range from 30m
to 200m. Multiple water strikes have been recorded in several boreholes tapping the Ecca
acquifer(s) with the deepest water strike logged at 301m. Borehole yields are variable and
range from dry to 60m3/hr.
2.8.4
Kalahari Group Aquifers
The Kalahari Group aquifers consist of a layer of Aeolian sand that may display relict dune
structures (mainly Barchans). At the present time, the sand is fixed by vegetation and the
dunes are considered to be fossil. A duricrust layer of silcrete and calcrete that must
represent an unconformity within the succession generally underlies the sand. Poorly
consolidated sandstones that are often calcareous underlie the duricrust. Where a full
succession is present, red marls and a basal clayey gravel of undoubted fluvial origin
underlie the sandstones. The thickness of the Kalahari succession is largely a function of
pre-Kalahari Group topography, with the gravels being largely confined to palaeochannels.
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The basal Kalahari gravels can constitute a useful aquifer. The Kalahari Group sediment
thickness around Bray in Botswana and Vryburg in South Africa indicate a broad 15-30km
wide trough of these sediments (in excess of 180m) forming a palaeovalley. The northern
flank shows several tributaries, which drain southwards into the palaeovalley. The
palaeovalley crosses the international border and passes into the Molopo Farms area.
There is high borehole density on the South Africa side of the border indicating extensive
abstraction of the groundwater resource on this aquifer. Thus the Kalahari aquifer(s)
constitute an important water supply source in the region, along with the Molopo and
Nossob rivers for both human and livestock populations. The water strikes range from 12m
to 72m with yields ranging from <1.0m3/hr to 8.6m3/hr.
2.9
Water Quality and Chemistry
Water quality is the major constraint on groundwater utilisation in the study area. The
groundwater over much of the southern and western Kgalagadi District is excessively
saline and large areas of the Otshe Formation sandstone aquifers and Kalahari group
aquifers are quite unusable. Salinity stratification is evident in the fracture aquifers of the
Olifantshoek Supergroup and pumping has the effect of drawing deeper, more saline fluids
into public supplies. The hydrochemistry of groundwater in the southern Kgalagadi has
been reviewed by Molebatsi (1994) who concluded that the salinisation is result of
dissolution of salt evaporites in the Kalahari Group (similar situation to the northern areas
of Namibia in the Ondangwa region).
The water quality in the basin area varies from fresh to hypersaline. The most important
ions contributing to the groundwater salinity are chloride, sulphate and sodium. As a result
there is good correlation between these ions and Total Dissolved Solids (TDS). Therefore,
the spatial distribution of TDS provides a good measure as well of chloride, sulphate and
sodium. The highest concentrations are in the boreholes near Khawa, in the northeast
section of the study area, just north of Middelpits, Gakhibane, and Rappelspan and
between Two Rivers and Tshane-Tshane. The lowest concentrations occur in Middelpits,
Khuis and Bogogobo and stretch further northwest to Khotswane.
Other occurrences of relatively low salinity water are in a few sections along the Molopo
and Nossob Rivers (around Gafrans and Drie-ertjies). Further east the groundwater quality
improves dramatically and few boreholes are reported to be saline east of Mabule. There
are a few relatively fresh water borehole samples that exhibit levels greater than the BOS
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32:2000 (Botswana Drinking Water Standards) DWA maximum permissible limit (max
100mg/l) supplying drinking water to Khuis, Gakhibane and Middelpits areas. Elevated
nitrate levels are usually indicative of organic contamination.
2.10 Transboundary Groundwater Resources
The Internationally Shared Aquifer Resources Management Programme (ISARM) was
established in 2000 in direct response to the challenges of shared water resources set out
in the Declaration of The Hague Ministerial Conference. The current understanding of
transboundary aquifers is poor as is the water resource management plan of such
resources. Present international law does not adequately address the issues concerning
spatial flow of groundwaters and has limited application. Scientific correlation of the
Geohydrology of such aquifers is often deficient and issues related to shared and
sustainable production remain blurred because of poorly developed institutions and lack of
capacity and awareness.
2.10.1
The ISARM Programme
The International Shared Aquifer Resource Management (ISARM) Programme operates
through a co-ordination committee drawn from UNESCO, FAO and the International
Association
of
Hydrogeologists
(IAH).
Each
of
these
organisations
provides
a
multidisciplinary initiative aiming to improve understanding of scientific hydrogeological,
socio-economic, legal, institutional and environmental issues surrounding the management
of transboundary aquifers. The ISARM programme is scheduled for completion in 2006
and its aim is to address the five key issues identified above. Specific project objectives
are :
· To establish a network of experts from different disciplines for identification and
definition of internationally shared aquifers
· To promote scientific, legal, socio-economic, institutional and environmental
assessment of internationally shared aquifer resources
· To identify several case studies of internationally shared aquifers and support
multidisciplinary expert teams to conduct detailed investigations
· To learn from case studies the issues relevant to good management of
internationally shared aquifer resources
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· To raise awareness of policy and decision makers of the significance and
importance of transboundary aquifer resources, forming a critical component of
the world's freshwater resources
· To disseminate the lessons learned from case studies and encourage policy and
decision makers to incorporate appropriate internationally shared aquifer
management
· To promote co-operation among experts from different countries that share
transboundary aquifers, through making available scientific tools, water resource
management options and methodologies that apply to such aquifers
2.10.2
Case Studies
One of the ISARM case studies, and relevant to this report, was carried out on the
Stampriet Artesian Basin that is shared by Namibia, Botswana and South Africa. The
Karoo Aquifer is predominantly utilised by Namibia where most of the recharge to the
aquifer probably occurs. The aquifer is a key component of human and economic
development in the arid environment of the Kalahari. The Lebung and Ecca Groups
located within the Karoo Supergroup host the main significant water bearing layers of the
Botswana Nossob Basin. Groundwater flow (hydraulic gradient) is to the east and
southeast. The northern part of the basin is the object of an ongoing resource evaluation
study, which is scheduled for completion by the end of 2005. The study will include the
establishment of a numerical model with abstraction simulations to supply settlements in
the region. Generally the Ecca Group sediments are represented by prograding (in the
normal direction of flow) delta sediments, which were fed by rivers draining the highlands
(Ghanzi Ridge) to the north. Southwards the deltas merged into a marine environment and
here hypersaline conditions prevail.
In Namibia, there is a comparatively good understanding of the geology and geohydrology
of the aquifer in the Stampriet Artesian Basin. Water occurs in the Auob and Nossob
sandstones of the Ecca Group as well as the overlying Kalahari Group sediments. The
strata dip approximately 300 towards the southeast and as in Botswana, the water quality
deteriorates in that direction as well. The Department of Water Affairs in Namibia was
undertaking construction of a numerical model of the aquifer.
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In the South African part of the basin, mainly along the Molopo and Nossob Rivers, the
known productive and potable aquifers are in the Kalahari Group and the inference is that
being down-gradient from the hypersaline Stampriet / Nossob Basin, the Ecca Group
sediments will be similarly saline. Point source information is available in the National
Groundwater DataBase. Water use, main recharge areas and general flow patters are
poorly known in that part of the aquifer. Water quality issues of elevated nitrate
concentrations are generally common throughout the Stampriet / Nossob Basin. These are
thought to relate to naturally occurring nitrate within the soil profile in addition to areas
where large concentrations of cattle occur. The nitrates are flushed down into the aquifer
following heavy rainfall events.
2.11 Aquifer Management Programmes
It is generally accepted that the thickness of the Kalahari sand, the duration and intensity
of rainfall events coupled with rate of evaportranspiration have great bearing on the
groundwater recharge potential in the Kalahari type environment. It has previously been
assumed that areas of no or limited Kalahari sand cover play and active role in the
recharging of any aquifers below the Kalahari Beds. It has thus been hypothesized that
when the Kalahari strata is fractured, a fair borehole yield with relatively good water quality
is more likely to be encountered in areas where there is no or very limited cover of the
Kalahari Beds. However, even if the Kalahari cover is thin but no fracturing has been
uncovered, the yields are still likely to be poor.
2.11.1
Recharge Research in Botswana
A research project (Groundwater Recharge Estimation Study ­ GRES) implemented by
the University of Botswana and DGS is association with the University of The Netherlands)
was setup to measure recharge rates in Botswana. This project resulted in the setting up
of complex climatic measurement stations. At present these stations are based at sites
close to four villages in Botswana with a variety of different climatic profiles. The
settlements and conditions are as follows:
· Tsabong ­ southwest and very dry
· Serowe ­ central and representative of most of Botswana
· Bere Mathoaaphuduhudu ­ west central and dry
· Maun ­ north in the Delta
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The stations have sap flow sensors and soil moisture sensors to depths of eight metres to
record moisture movement through the unsaturated zone. These ground stations also
incorporate measures to record the following parameters :
· Incoming and outgoing solar radiation
· Incoming and outgoing thermal radiation
· Relative humidity profiles
· Air tempreture profiles
· Wind speed
· Soil heat flux
· Rainfall
· Groundwater level fluctuations
The study involved qualitative descriptions of recharge based on a combination of
hydrochemical and hydraulic methods; assessment of long-term and short-term recharge
using hydrochemical and hydraulic methods; quantification of recharge within the zones
from groundwater flow models. The main features of the hydrochemical work were isotope
studies, noble gas sampling and chloride mass balance.
Results from GRES have so far estimated recharge in the Letlhakeng ­ Botlhapatlou area
(at the fringe of the Kalahari) at around 7mm/yr, with a decrease to less than 1mm/yr in the
Central Kalahari. It appears that a critical threshold of 400mm/yr rainfall is essential for
recharge. In 2000, the International Institute of Aerospace Survey and Earth Sciences set
up a further eight sites in the Kalahari as a result of the Kalahari Research Programme ­
Establishment of Monitoring Network for Water Balance Studies. The work is ongoing
A variety of methods for estimating recharge are currently applied in Southern Africa
(including Botswana). As a result recharge rates have been calculated for wellfields in the
study area in several previous investigations and assessments. A number of methods
have been applied to estimate recharge, with chloride mass balance been the most
common. These results are often coupled with groundwater modeling to produce refined
estimates. Recharge estimates using various methods from such projects, which were
conducted in some parts of the study area are presented in Table 2-9.
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Table 2-9: Recharge Estimates for Basin Area from Previous Projects Undertaken
Recharge
Wellfield
Method
Ref
Recharge Area
(mm/yr)
Chloride mass
Widespread
Matsheng
0.1 ­ 23
DGS, 1996b
balance
Chloride mass
Fractured quartzite
Tsabong
0.16 - 77
DWA, 1993
balance
Widespread over Kalahari
Werda Sekoma
Isotopes
6 - 8.6
DWA, 2003
area
Sikamatswe
CRD
0.1 - 2.3
DGS, 2003
Sikamatswe
Molopo River Bed CRD
0.1 - 2.3
DGS, 2003
Molopo River Bed
Recharge estimation in the Kalahari requires much attention due to its role in sustainability
of any groundwater development of whatever nature. The estimation of recharge in semi
arid to arid environments, such as the Kalahari, has been proven to be rather difficult. Not
much has been done in terms of employing other methods, which could give a better
understanding of the replenishment of the aquifers within the study area.
2.11.2
Hydrogeological Mapping
Detailed hydrogeological maps of various types and scales are available in Botswana.
They include:
· Hydrogeological reconnaissance maps (1:250,000) that summarise the
hydrogeological data for areas; the information includes yield potential, water
quality and where possible, flow directions (hydraulic gradient)
· Groundwater vulnerability maps in various scales
· Extensive regional and local maps are present in various reports on projects
2.11.3
Groundwater Monitoring
The Monitoring Section of DWA carries out monitoring of groundwater levels and
abstraction quantities. Together with boreholes monitored by the DGS, a total of
approximately 800 boreholes are monitored. The vast majority of these boreholes are
hand dipped, with 57 equipped with chart recorders and 23 using transducers. Data for
wellfields, operated
by
non-governmental
organisations
(such
as
Water
Utilities
Corporation, mining operations) are provided to DWA and summarised in the Water
13/11/2007
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Task 6: Groundwater
Apportionment Board (WAB) annual reports. Since 2000, both DWA and DGS have
installed standardised digital automatic water level recorders.
2.11.4
Databases
The Department of Geological Survey has historically maintained a mainframe National
Borehole Archive (NBA). The NBA is a somewhat archaic and antiquated MS-DOS based
stand-alone system and does not support multiple-user configurations. As such, it is
maintained by DGS with a copy at DWA. DGS is responsible to provide periodic updates
to. However, this occurs infrequently.
The National Borehole Archive is populated from the data recorded on Borehole
Completion Certificates (BCC). However, some four years ago it was wisely decided a new
system would be implemented and so data input into the old DOS based system was
terminated. In 2002 a new hydrogeological database (GeoDin) was launched but it
contained only the little data that was available to be transferred from the old NBA. It was
intended that all the BCCs would be entered into the system. Currently data is not being
entered in the GeoDin system, as the system is unserviceable. There is thus a huge
backlog of data.
The Department of Water Affairs maintains separate databases as a response to the
limitations of the existing database arrangements. WELLMON is a software package for
groundwater monitoring data, climatic data etc. used to produce groundwater hydrographs.
The data stored in WELLMON does not include all the data that had been collected during
an audit into wellfields. DWA had managed their version of WELLMON for the wellfields
they are responsible for. DGS, conversely, had not entered much of the data that were
collected over the years. Water level recorders are installed in 55 boreholes located in
some 19 wellfields. The recorders provide a continuous measurement of water level
fluctuations, if and when functioning properly. The recorders are maintained by DGS, and
to a lesser degree by DWA, who in theory visit them on a monthly basis to replace the
charts. Due to a lack of human resources, DGS has been unable to digitise most of the
charts for entry into the WELLMON system.
The quantity and quality of the data obtained from the charts were found to be very poor
indeed. Some of the problems found are :
· The vertical scale was incorrectly set, which caused the water level to plot off the
chart. Training should be given to all concerned
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· Drum turned too slowly
· Pen got stuck or ink dried up, rendering the data incomplete and useless
· Chart was not collected within 30 days which results in the printing of two or more
water level data
Abstraction data is stored in WELLMON and the data sets are from time to time somewhat
problematic and generally the data within the WELLMON is poor.
2.11.5
Available Groundwater Reports of the Study Area
Numerous groundwater studies have been conducted in the study area resulting in several
reports, which may be useful a reference material in any future groundwater development
programmes in the area. Table 2-10 below presents a list of available reports discussed
above. The confidence level is indicative of the level of accuracy of the facts as presented
in such reports.
Table 2-10: Available Groundwater Reports for the Basin Study Area
Title
Author
Date
Format
Confidence
Level
Botswana Master Plan for
Department of Sanitation
2002
Hardcopy
Low
Waste Water. Inception
and Waste Management
report.
Botswana National Water
SMEC, WLPU
1991
Hardcopy
Low
Master Plan. Final Report
Consultants and Swedish
Volume 5, Geohydrology.
Geological International
Groundwater Potential
Water Surveys
1994
Hardcopy
High
Survey Middlepits /
(Botswana) for the
Makopong TGLP Areas.
Department of Geological
Final Report Vol I Text,
Survey
Vol II Inventory of
Boreholes, Vol III A
Project Boreholes, Vol V
Geophysical Data,
Middlepits And Tsabong
Water Surveys
1994
Hardcopy
High
TGLP Groundwater
(Botswana) for the
Potential Study, Final
Department of Geological
Report.
Survey
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Task 6: Groundwater
Title
Author
Date
Format
Confidence
Level
Tsabong Groundwater
Resources Services (Pty)
2003
Hardcopy
High
Investigation, Assessment
Ltd For the Department of
and Digital
and Development, Final
Water Affairs
Copy
Report,
Groundwater Potential
Wellfield Consulting
2003
Hardcopy
High
Survey Werda Sekoma
Services for the
and Digital
TGLP. Final Report.
Department of Geological
Copy
Survey
Groundwater Potential
Geoflux (Pty) Ltd for the
2002
Hardcopy
High
Survey Bokspits TGLP
Department of Geological
and Digital
Areas. Final Report.
Survey
Copy
Matsheng Area
Wellfield Consulting
1996
Hardcopy
Medium
Groundwater Investigation
Services for the
(TB 10/2/12/92-93) Final
Department of Geological
Report...
Survey
Water Supply
Hydrogeo (PTY) Ltd For
2000
Hardcopy
Medium
Rehabilitation Programme
the Department of Water
Kokotsha, Kgalagadi
Affairs
District. Final Report.
SADC/WSCU
Bee Pee Groundwater
2001
Hardcopy
Low
Development of Code of
Consultants
Practice for Groundwater
Development in the SADC
Region Report No1 (Final)
Situation Analysis Report
Hydrogeological
Mukupadhyay, S.K.
1983
Hardcopy
Low
Investigation of the
Malejane, R.M and
Molopo Farms DGS
Sutcliffe, H.M
unpublished Report
SKM/2/83
Consolidated Emergency
TTCS Groundwater
1990
Hardcopy
Medium
Programme (II) Sekoma,
Consulting Services For
Maralaleng, Werda and
the Department of Water
Sekoma-Makopong Road.
Affairs
Final Report Volumes 1
and 2.
Hydrochemistry of the
Phofuetsile, P.
1988
Hardcopy
Low
Groundwater in the
University College of
Kalahari, Southern
London
Botswana. Unpublished
MSc. Thesis
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Task 6: Groundwater
Title
Author
Date
Format
Confidence
Level
Consolidated Emergency
TTCS Groundwater
1989
Hardcopy
Medium
Programme (I) Makopong,
Consulting Services For
McCarthy's Rust,
the Department of Water
Draaihoek Vaalhoek and
Affairs
Bray Final Report
2.11.6
Water Quality DataBase
The database contains water quality analyses of surface and groundwaters. This database
unfortunately does not contain and detailed positional data rendering it quite useless. The
very thought of a database of this nature not containing positional data simply defies logic.
A new testpumping database is in the process of being established. Attempts have been
made to link the various databases but human resource limitations and lack of capacity
has apparently thwarted the process. Both DWA and DGS update their separate
databases independently and most of the time duplicates each other's efforts. There is
definite scope for streamlining and improvement.
2.11.7
Department of Surveys and Mapping DataBases
The Department of Surveys and Mapping has a wealth of information available generally
referred to as Land Information. The setup of the updating and retrieval of this information
is done within a digital system known as a Land Information System. The content is of the
data stored is broad and its potential uses is presented in Figure 2-7.
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Orange IWRMP
Task 6: Groundwater
Administration
Statistics
Fire
Maps for Administration
Census Map
Street and Plot
Buildings, Sewerage, Construction
Population
Number Maps
Environmental Conservation
Density Maps etc
GIS
Geological Minerals
Planning
Topo Maps showing Site Development
Topo and Cadastral Maps for Residential
Coordinates Mineral Interest
Industrial layout both Urban/Rural
Cadastral Dat for Mining Lease Area
Topo/CAD for all Physical Planning
Transport
Air Communications
Road Surveys and Maps
Horizontal and Vertical Controls
Topo Maps for the Definition of Airspace
Topo Maps of Railways and for Navigation
Control and Engineering
Precise Position Fixing for Beacons
Business and Industry
Forrestry
Urban and Rural Cadastral Maps
Topo Maps for Pest Control and Tree Conservation
Topographic and Wildlife Management Maps
Satellite Imagery for Monitoring
Scientific Research
DEPARTMENT OF
Flooding
High Precision Geodetic Control
SURVEYS AND
Plate Tectonics and Dam Movement
Topo Maps for Flood Area Investigation
Areas liable to Flooding
MAPPING
Cadastral Dat for Mining Lease Area
Rating Land and Housing
Data for Property Valuation and
Land Management
Agriculture
Cordon Fences Map
Pests Research and Control
Survey Firebreaks for Veld Fire Control
Contour Maps for Crop Farm Planning
Meteorological Services
Detail Plan for Tree Conservation
Geographical Maps of Villages
Disease Control Maps
Magnetic Variation
Urban and Rural Development
Community Development
Water Resources
T Utility Plans
Cadastral Data for Lease and Titles
Topo Maps for Irrigation and Wells
Compensation
Topo Maps for Construction of Recreational
Dams and Pipeline Construction
Provision of Infrastructure
Facilities
Topo Maps for Servitude
Data for Land Information
Figure 2-7: Land Information available at the Department of Surveys and Mapping
2.12 Potential and Planned Groundwater Utilisation Projects in the Basin Area
According to the Kgalagadi District Development Plan Six, the Botswana Defence Force is
planning to erect a base camp in the Tsabong area. The camp is to provide both office and
residential accommodation. It is currently not clear how large a development this is but it is
understood to be a regional camp and may house up to 100 officers and families plus
enlisted personnel. The National Master Plan for Agricultural Development (NAMPAD) of
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Botswana has proposed some irrigation projects to be undertaken in the study area. The
main proposed project is the establishment of vineyards in Tsabong to take advantage of
the extensive sunshine and favourable conditions. The water is to be sourced from the
Waterberg aquifers, which are currently exploited to supply drinking water for Tsabong and
surrounding villages. Local farmers abstract minor quantities of water for stock and other
watering from the aquifer. The planned maximum abstraction is estimated at 1 829
000m3/annum. NAMPAD estimates that the Molopo River in the Tsabong area has the
potential of adequate groundwater and thus the envisaged vineyards irrigation project
water demand would be comfortably met. Given the fact that the aquifer concerned
straddles Botswana and South Africa, it is thus strongly recommended that a full water
demand study be undertaken before this programme proceeds with implementation
NAMPAD has also planned further irrigation projects further east around Ngwaketse
South. The groundwater source would be the Kanye wellfield (Transvaal Supergroup
Dolomites aquifer). The planned water demand to meet these new developments is some
6.19x10m3/annum while the proposed wellfield has a potential groundwater production of
5x10m3/annum. The shortfall will be met with the harnessing of potential wastewater
reclamation from Jwaneng and other boreholes. Clearly this shortfall should raise red flags
and further planning and investigation should to be done before the project is cleared for
implementation.
2.13 Reports and References
Bekker, R. P. & de Wit, P. V. (1991), Contribution To The Vegetation Classification Of
Botswana. FAO/UNDP/Ministry of Agriculture Gaborone
Beukes, N.J., (1990) Report on Stratigraphic Correlation of some drill core intersections in
the Keng Pan, Tubane and Phepheng Areas, Molopo Farms Complex, Unpublished report,
Molopo Botswana (Pty) Ltd.
Bhalotra Y.P.R (1987) Climate of Botswana. Part II Elements of climate. 1. Rainfall, 2.
Sunshine and Solar Radiation and Evaporation. 3 Temperature and humidity of the
Department of Meteorological Services
MOW, 2002. Botswana Master Plan for Waste Water. Department of Sanitation and Waste
Management. Inception report. Gaborone.
Botswana National Water Master Plan (1991). Final Report Volume 5 ­ Geohydrology.
Prepared by SMEC, WLPU Consultants and Swedish Geological International
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Orange IWRMP
Task 6: Groundwater
Bredenkamp, D.B., Botha, L.J., van Tonder, G.J., and van Rensburg, H.J., (1995)
Manual on Quantitative Estimation of Groundwater Recharge and Aquifer Storativity,
Water Research Commission, Pretoria
Carney J.N., Aldiss D.T. and Lock N.P., (1994) The Geology of Botswana, Department
of Geological Survey. Bulletin 13.
CSO (Central Statistics Office) (2002) Population of Towns, Villages and Associated
Localities in August 2001. 2001 Population and Housing Census
DGS (1984)
The Kalahari Drilling Project. Bulletin 27. Authors. Meixner, H.M. and
Peart, R.J. DGS, 1994
DGS (1994) Groundwater Potential Survey Middlepits / Makopong TGLP Areas. Final
Report Volume I Text, Volume II Inventory of Boreholes, Volume III A Project Boreholes,
Volume V Geophysical Data, prepared by Water Surveys (Botswana)
DGS, (1996), Matsheng Area Groundwater Investigation (TB 10/2/12/92-93) Final Report.
Wellfield Consulting Services.
DGS, (2002) Groundwater Potential Survey Bokspits TGLP Areas. Final Report. . Geoflux
(Pty) Ltd.
DGS, (2003). Groundwater Potential Survey Werda Sekoma TGLP. Final Report. Wellfield
Consulting Services.
DWA (1993) Protection Zones for Major Wellfields, Aquifers and Dams in Botswana. Final
Report. Water Surveys (Botswana) Ltd.
DWA (2003) Tsabong Groundwater Investigation, Assessment and Development, Final
Report, prepared by Resources Services (Pty) Ltd.
Farr, J. L. et al (1981), GS 10 Project Evaluation of Underground Water Resources Final
Report. Department of Geological Survey.
Key, R.M., (1979) A report on a field trip to Southwest Botswana. Unpublished report.
Geological Survey of Botswana
Key, R.M. and Tidi. K.J, (1987) Sheet 32, Tsabong, Geological Survey of Botswana
Key, R.M, Tidi, J, McGeorge, I, , Aitkin, G, Cadman, A, and Anscombe, J, J. (1998)
The Lower Karoo Supergroup geology of the southeastern part of the Gemsbok Sub-basin
of the Kalahari Basin, Botswana. S. Afr. J. Geo 101(3), 225-236.
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Orange IWRMP
Task 6: Groundwater
Smith, R.A. (1984), The Lithostratigraphy of the Karoo Super Group in Botswana.
Department of Geological Survey. Bulletin 26. Author.
SACS (1980), Stratigraphy of South Africa, Part! (Compiler L. E Kent) Handbook of the
Geological Survey of South Africa
Van Straten, O. J. (1955), The Geology and Groundwater of The Ghanzi Cattle Route
Ann. Rept. Geological Survey Bechuanaland. Prot Water Surveys Botswana 1994).
Water Surveys Botswana (1994), Middlepits And Tsabong TGLP Groundwater Potential
Study, Final Report. Department of Geological Survey.
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3
NAMIBIA GROUNDWATER OVERVIEW
ORASECOM, the Orange-Senqu River Commission was established to enable Integrated
Water Resources Management Planning for the Orange River Basin. The purpose of this
section is to review the Namibian groundwater resources to provide relevant (existing)
information for a meta-database to be developed for ORASECOM. Figure 3-1 shows the
Namibian catchments of the Orange River. As can be seen, the upper part of the Auob is
cut off from the lower section; Oanob and Schaap end in a dune field northeast of
Kalkrand. Likewise, below the confluence of the Auob and Nossob Rivers the river course
of the Molopo is blocked and even large floods from the sub-catchments do not reach the
Orange River.
Figure 3-1: Namibian Catchment of the Orange River with Sub-Catchments
3.1
Historical Development of Water Affairs (DWA) in Namibia
Recorded drilling activities started early in the last century when the German colonial
government operated a "Bohrkolonne" in the central and northern parts of Namibia and a
"Bohrkolonne Sud" in the southern half of the country. Some early borehole data can be
found in the National Archives as well as some early publications (Range, 1915). The
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Task 6: Groundwater
German "Schutzruppe" had their own drilling rigs. After World War I, the South African
Irrigation Department became responsible for drilling on new farming land to be issued to
ex-soldiers. Sometime during the late 1930s the SWA Works Department took over the
drilling activities. Later an independent Water Affairs Branch was instituted. In the 1960s
the Geological Survey was established as the entity also responsible for Geohydrology.
In the late 1960s the whole SWA Administration was placed under the respective South
African Departments in Pretoria and the SWA Water Affairs Branch became a subsidiary
of the Department of Water Affairs in South Africa. Following South Africa, the
Hydrogeological Section of the SWA/Namibian Geological Survey was transferred to the
Department of Water Affairs in 1977. Under the new Namibian Government, Water Affairs
has fallen under several different Ministries and is currently part of the Ministry for
Agriculture, Water and Forestry.
Under this Ministry the Bulk Water Supply Section of the Department of Water Affairs has
been commercialised and NamWater now operates all Bulk Water Schemes. Apart from
bulk water supply, NamWater also supplies some rural communities on contract to the
Directorate of Rural Water Supply (RWS), although the majority of rural water supply
schemes are initiated and operated by the Directorate of RWS.
3.2
Climate
Namibia is the driest country south of the Sahara. The only perennial rivers are the border
rivers of the Orange, Cunene and Okavango and Zambezi.
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Task 6: Groundwater
Figure 3-2: Rainfall Distribution
Figure 3-2 shows the rainfall distribution that varies from 700mm in the northeast to less
than 50mm along the Atlantic Coast. The Orange River sub-catchments fall into an area
that receives generally less than 250mm/yr while the potential evaporation is estimated at
more than 3700mm/yr.
3.3
Population Density
The present population of Namibia is estimated at around 1.8 million people. The majority
of these live in the northern half of the country. Maltahohe, Bethanien and Karasburg
Districts have population densities of less that 0.25 persons/km2; Keetmanshoop and
Mariental between 0.25 and 0.5 persons/km2 while the communal area of Namaland and
the Gobabis District have densities of around one person/km2.
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Task 6: Groundwater
3.4
Economic Activities
Mining, agriculture and tourism are the main economic sectors in the study area.
Agriculture is by far the largest sector with stock farming predominating. In recent years
ostrich farming commenced in the Mariental and Keetmanshoop Districts and Karakul
breeding has gained significant importance. Irrigation farming (lucerne, grapes and citrus
and vegetables) are grown at the Hardap Scheme near Mariental and in the Stampriet
Artesian area. Some irrigation also occurs below the Naute Dam (Figure 3-3). Large
irrigation farming occurs along the banks Orange River.
Figure 3-3: Irrigation Below Naute Dam
Rosh Pinah and the recently developed Scorpion mine are two of the major mines located
within the Fish River Catchment. Mining at the Haib Copper deposit near Nordoewer has
not started. The diamond deposits of Oranjemund at the mouth Orange River are well
known. Tourism is of lesser importance although the Fish River Canyon and the Ai-Ais Hot
Springs are major attractions. Further points of interest are the Quiver Tree Forest and the
Giants Playground near Keetmanshoop.
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Task 6: Groundwater
3.5
Geology
Damara schists and Nosib quartzites seem to predominate in the northernmost part of the
basin. The Stampriet Artesian Basin lies in the central eastern section of the area and
stretches into Botswana. Here artesian Nossob and Auob sandstone are separated and
overlain by shale horizons under sediments of the Kalahari Sequence. To the west in the
Fish River catchment the area consists mainly Nama-aged sandstone, shale and
limestone. Karoo and Nama lithologies as well as dolerite intrusions are to be found in the
southern section and Kalahari sediments occasionally overlie these lithologies.
Figure 3-4: Namibian Geological Map
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Task 6: Groundwater
3.6
Geohydrology and Hydrology
The meteorological services of DWA and NamWater mainly operate the rainfall stations. In
the Namibian Orange River sub-catchments there are a total of 284 stations on record
(see Figure 3-5) that are or have been in operation for some time. The Hydrology Division
of the Department of Water Affairs has compiled a Unit Runoff Map of Namibia at a scale
of 1 : 1 000 000 depicting the relatively high unit runoff for the Fish River catchment.
Runoff values reach up to 25mm in the southern Rehoboth District and around 10mm in
the Weissrand area (between Mariental and Stampriet).
Figure 3-5: Approximate Position of Rainfall Stations
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Task 6: Groundwater
A total of 25 gauging stations are operated in the Namibian Orange River sub-catchments;
three of them by NamWater and the remainder by DWA (the approximate positions are
shown in Figure 3-6).
Figure 3-6: Gauging Stations in the Orange River Sub-Catchments
The groundwater potential or natural recharge of the country has not yet been fully
determined. It is estimated that between one and two percent of rainfall actively recharges
the Namibian groundwater. For some schemes and projects the safe yield has been
determined but since recharge is rainfall dependent and as rainfall is highly variable in
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Namibia, such values must be viewed with caution. In addition, groundwater potential
information for certain areas does exist in certain reports (for Tsumeb and Stampriet etc.)
but these have not yet been consolidated into a single report. A qualitive overview is
presented in the Hydrogeological Map of Namibia (van Wyk, Straub et al. 2001).
3.6.1
Water Level Monitoring
Borehole loggers and recorders have been in operation at selected groundwater
dependant towns and villages. Water levels are also monitored in the Stampriet Artesian
Basin (south of Gobabis and east of Mariental). During a recent Japanese funded
development project, ten additional observation boreholes were drilled to monitor the
hydraulic characteristics of various aquifers in the area (Kalahari, Auob and Nossob
aquifers). See Figure 3-7 below for locations.
Figure 3-7: Locations of water level monitoring points
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3.6.2
Data Formats - Hardcopy
There are some 40 000 records of Borehole Completion Forms of WW-numbered
boreholes. The captured data records farm name and number, borehole depth, water
strikes and associated yields, lithology and casing and more recently drilled boreholes
include GPS data. The Department of Water Affairs owns the data sets. Some 90 000
water chemical analyses of mainly major ions plus some bacteriological data is also
available. Many operational analyses from distribution networks and chemical data from
numerous groundwater schemes are also available from DWA.
In addition, there are some 30 000 groundwater samples analysed by the CSIR during the
CSIR Water Quality Project between 1965 and 1981. NamWater reports on production
borehole utilisation rates on a monthly basis.
3.6.3
Data Formats ­ Electronic
There is a relatively complete set of captured data of the more important borehole
parameters drilled before about 1990. Changing database platforms coupled with the new
development of these databases and a lack of resources and capacity has led to a
substantial backlog in the transferring of the datasets. A new database (GROWAS)
became operational towards the end of 2004. Most rainfall data and surface water
abstraction information (dams) is available in an electronic format.
DWA water analyses done prior to the 1980s (about 50 000 records) exist only as paper
copies and some data captured in an ACCESS database since cannot be identified for
various reasons. No further clarity on the issue is available. The balance of the data is
available digitally but is somewhat awkward due to poor design and structure of the
databases. More recent analyses are stored as (for some obscure reason) individual
EXCEL spreadsheets so it seems logical that migrating these spreadsheets to ACCESS or
similar should not be too complex a task. The CSIR Water Quality Map analyses data
sheets have recently been captured and available in an EXCEL spreadsheet.
3.7
Groundwater and Surface Water Abstraction
In the existing Water Act of 1956, permits for large-scale groundwater abstraction are only
required in Groundwater Control Areas of Namibia (see Figure 3-8). In the Orange River
sub-catchments these are the Windhoek ­ Gobabis areas; the Stampriet Artesian Basin (in
the map legend termed Windhoek-Gobabis-Mariental); and the Maltahohe artesian area.
Good records exist for the Stampriet Artesian Basin. No permits are required for the
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Hardap Irrigation Scheme and no records exist for the Maltahohe area although it is known
that grapes are grown on the Farm Neuras. In the past, irrigation also took place around
Namibia's largest private dam on the Farm Voigtsgrund in the Maltahohe District. It is not
recorded whether irrigation continued after the Namibian Government acquired the
property. A list of all the permits for abstraction from the Orange River indicates there are
13 permit holders with a total annual abstraction allocation of some 45MCM/a.
Figure 3-8: Groundwater Control Areas in Namibia
3.7.1
NamWater Schemes
The eight dams in the sub-catchments of the Orange River are shown in Figure 3-9. The
capacity and mean annual abstraction for the major six are given in Table 3-1. The
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Orange IWRMP
Task 6: Groundwater
capacities of the Nauaspoort and Bondels Dam are 3.32 and 1.3Mm3 respectively. The
recorded mean annual abstraction from all six dams is given as 50.75Mm3.
Table 3-1: Mean Annual Abstraction from Six Major Dams
Dam Name
Capacity
Period
Mm3/a
Hardap
294.59
1994-2004
42.279
Naute
83.58
1994-2004
4.739
Oanob
34.51
1995-2004
2.653
Otjivero
9.74
1996-2004
0.649
Tilda Viljoen
1.22
2000-2004
0.403
Dreihuk
15.49
1999-2004
0.119
Figure 3-9: Dams in the Namibian Sub-Catchments of the Orange River
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3.7.2
Groundwater Schemes
NamWater operates some 13 schemes in the Karas and Hardap Regions and two in the
Omaheke and Khomas Regions supplying towns, villages and settlements as well as the
Ai-Ais Resort. Mean monthly production and the number of boreholes of the respective
schemes are listed in Table 3-2.
Table 3-2: NamWater Schemes in the Sub-Catchments of the Orange River
HARDAPREGION
KARASREGION
KHOMASREGION
OMAHEKEREGION
Monthly
Monthly
Monthly
Monthly
Scheme
Scheme
Scheme
Scheme
Production
Production
Production
Production
Boreholes
Boreholes
Boreholes
Boreholes
Aminuis
2
2000 Ai-Ais
8
5550 Dordabis
4
1860 Gobabis
30
144690
Aranos
9
46200 Ariamsvlei
4
6510 WindhoekAirport
12
17170 Witvlei
2
16200
Gochas
3
9000 Aroab
7
9690
Gibeon
2
48000 Berseba
2
4500
Kalkrand
3
19500 Bethanie
2
36750
Kries
2
2610 Gabis
3
3623
Kwakwas
2
Gainachas 2
525
Leonardvil e
3
10200 Grünau
6
1134
Maltahöhe
3
19200 Karasburg
8
14400
Oamites
3
23640 Köes
2
12240
Onderombapa
2
5940 Kosis
2
3960
Schlip
5
16920 Tses
8
25080
Stampriet
2
9300 Warmbad
2
2400
Total
212510 Total
126362 Total
19030 Total
160890
3.7.3
Stock Watering
The water demand for stock watering in about 50l/day for large stock units (cattle) and in
the region of 5l/day for small stock units. Stock watering requirements are about 5l/ha/day
in the northernmost parts of the sub-catchments and decrease somewhat in the
southernmost areas. These values are rough estimates only, based on available
information.
The study area size in calculated to be about 23.175 million ha. If one uses a carrying
capacity of 15ha as an average, an estimated stock watering demand of some 3MCM/a
would be required for stock watering.
13/11/2007
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57

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Orange IWRMP
Task 6: Groundwater
3.7.4
Other Users
Unfortunately (and rather surprisingly) no information for the water consumption of the
mines at Rosh Pinah, Scorpion and Oranjemund is available. Excluding these, a total
annual water abstraction of 114MCM can be accounted for. Apart from the unaccounted
mining sector abstraction rates, further allowances have been made for human
consumption, gardening and water losses on farms etc.
3.8
Water Quality
A comparatively comprehensive groundwater quality database exists since the CSIR
sampled and analysed most equipped boreholes and wells in the 2nd half of the 1960s and
the 1970s with nearly 30,000 analyses displayed on four 1:1,000,000 maps. In addition to
water quality issues, information listed includes borehole depth, yield, strike depth and
water level, lithology and application. It remains unclear if the map database has been kept
up to date.
Figure 3-10: TDS Values According to Namibian Water Quality Guidelines
13/11/2007
Final
58

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Orange IWRMP
Task 6: Groundwater
The groundwater chemistry is mainly of good quality and poor groundwater quality is
generally confined to the southeastern corner of the Stampriet Artesian Basin. Elevated
Nitrate levels are found in the same area but also appear to be slightly more widespread
(see Figure 3-11). This is particularly true of the Kalahari and Kalkrand Basal aquifers
along the western margin of the Stampriet Artesian Basin.
Figure 3-11: Nitrate Levels According to Namibian Water Quality Guidelines
3.9
Report and Information Listing
All the reports are held at the Department of Water Affairs and the format is mainly paper
copies and only some reports after the early 90s are available digitally. Generally an
acceptable confidence level can be expressed in these reports. The following is a list of
available reports (all information is also available in a metadata file on the CD
accompanying this report).
13/11/2007
Final
59

---

Orange IWRMP
Task 6: Groundwater
(1964). Diamond core drilling, site and surface investigation for Naute Dam SWS.- Report
(1969). Rosh Pinah Mine, S.W.A.: HISTORICAL.- Report
(1975). Hidrologiese ondersoek Asab omgewing.- DWA/Windhoek: Report
(1977).
Olifantswater:
Completion
reports;
Pump
test
and
Letters.-
Geohydrology/DWA/Windhoek: Report
(1978).
Addendum
tot
die
verkenningsverslag:
Watervoorsiening
aan
Aroab.-
DWA/Windhoek: Report
(1978). Beplanningsverslag : Addendum tot die verslag NR 3120/R7/1 watervoorsiening
aan Rehoboth.- DWA/Windhoek: Report 3120/R7/1, 18 pp.
(1978). Geologiese opname - Artesiese gebied Stampriet (Lidfontein omgewing).-
Geological Survey/Windhoek: Report
(1978). Groundwater potensiaal van Namaland.- Geohydrology/DWA/Windhoek: Report
GH 490/2, 19 pp.
(1978). Namaland groundwater potential report GH 490/2.- Geohydrology/DWA/Windhoek:
Report
(1978). Navorsingsverslag :Probleme as gevolg van en oplossing vir die hoë water tafel.-
Geohydrology/DWA/Windhoek: Report
(1978). Navorsingsverslag: Probleme as gevolg van en oplossing vir die hoe watertafel.-
DWA/Windhoek: Report
(1978). Planning report Kosis State Water Scheme.- DWA/Windhoek: Report 10 pp.
(1978). SWA Coal Project (Aranos Basin).
(1978). Tses watervoorsieningskema: Voorgestelde aanvullende watervoorsieningskema.-
DWA/Windhoek: Report 10 ppü.
(1978).
Tugela:
Completion
reports;
Pump
test
and
Letters.-
Geohydrology/DWA/Windhoek: Report
(1979).
Beplanningsverslag
oor
die
voorsiening
van
water
aan
Maltahöhe.-
DWA/Windhoek: Report 490/39/3, 25 pp.
(1979). Goedkeuring van fondse vir die bou van die Grünau Staatwaterskema.-
DWA/Windhoek: Report 14 pp.
13/11/2007
Final
60

---

Orange IWRMP
Task 6: Groundwater
(1979).
Potential
report
on
the
groundwater
conditions
at
Aranos.-
Geohydrology/DWA/Windhoek: Report
(1981). Various reports: Boorplekaanwysings Namaland, Gibeon area.- DWA/Windhoek:
Report
(1984).
Beplanningsverslag
oor
die
voorgestelde
Duineveld
Staatwaterskema.-
DWA/Windhoek: Report 3100/2/7/81, 16 pp.
(1984). Fish River catchment basin : Water supply.- DWA/Windhoek: Report
(1984). Investigation into the feasibility of conjunctive utilisation of the proposed HARIS
RIVER DAM with the downstream aquifer.- DWA/Windhoek: Report
(1985). The development of the Fish River catchment basin with special reference to water
supply.- DWA/Windhoek: Report
(1987). Euro Namibian investment Co. Ltd.: Aranos Coal Deposit Locality Plan.
(1987). Preliminary feasibility report on the irrigation possibilities along the lower Orange.-
Planning Division/DWA/Windhoek: Report
(1987). Vergadering onder die voorsitterskap van die Minister van Landbou, Waterwese,en
Seevisserye met grondeienaars wat binne die geproklameerde Stampriet, Gochas,
Leonardville, Aranos ondergrondse waterbeheergebiet val.
(1987). Vergadering onder voorsitterskap van die Ministerie van Landbou, Waterwese en
seevissery met grondeienaars wat binne die geproklameerde Stampriet Gochas,
Leonordville, Aranos ondergrondse waterbeheergebied val.- Report
(1988).
Databank
Area
3:
Reports
and
letters
on
Stampriet
Artesian
Area.-
Geohydrology/DWA/Windhoek: Report
(1988). The development of the Fish River catchment basin with special reference to water
supply.- DWA/Windhoek: Report
(1990). Ariamsvlei staatwaterskema: 'n Ondersoek na die grondwaterpotential en
ontsluiting
van
addisionele
grondwaterbronne
in
die
Ariamsvlei-omgewing.-
Geohydrology/DWA/Windhoek: Report 28 pp.
(1990). Ontwikkeling van warm waterbron.- Report
(1991). Memorandum on recent fieldwork and drilling proposal.- DWA/Windhoek: Report
13/11/2007
Final
61

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Orange IWRMP
Task 6: Groundwater
(1995). Map of approximate locations rural geo.
(1996). Planning memorandum on the upgrading of the Tses SWS.- DWA/Windhoek:
Report
(1997). Groundwater exploration for the extension of the Grünau State Water Scheme.-
DWA/Windhoek: Report
(1997). Report groundwater exploration for the extension of the Tses State Water
Scheme.- Geohydrology/DWA/Windhoek: Report
(1997). Stampriet Water Committee Meeting on 14 March 1997.- Report
(1998). Final report groundwater exploration for the extension of the Tses State Water
Scheme.- Geohydrology/DWA/Windhoek: Report
(1999). Managing water points and grazing areas in Namibia Karas and Hardap.- Report
(undated). The artesian area in South West Africa.- Geological Survey/Report 20 pp,
Appendix.
(undated). Geologiese seksies Subartesiese Kom Stampriet.- Geological Survey/Report
File G.O. 14/17/2/6/1,
AgipCarbone (1984). Namibia Coal Project.- AgipCarbone/Report 15 pp.
AgipCarbone (1984). Report on the 1984 exploration campaign in the Aranos area.-
Report
Apolloner, V. (1985). Geohydrological report on groundwater investigation for the water
supply for Gibeon.- Geohydrology/DWA/Windhoek: Report
Apolloner, V. (1985). Geohydrological report on groundwater investigation for the water
supply of Kalkrand.- Geohydrology/DWA/Windhoek: Report
Apolloner, V. (1985). Geohydrological report on groundwater investigations for the water
supply of Gibeon.- DWA, Windhoek/Report Geohydrology report 291/G11/7, 10 pp.
Apolloner, V. (1990). Dreihuk-Karasburg State Water Scheme. Supply potential from
Dreihuk dam.- DWA/Windhoek: Report Geohydrology Report 12/7/G10, 11 pp.
Apolloner, V. and F. Bockmühl (1990). Results of the investigations of groundwater
resources to supply Karasburg. Karasburg-Dreihuk State Water Scheme.- DWA,
Windhoek/Report Geohydrology Report 12/7/G10, 31 pp.
13/11/2007
Final
62

---

Orange IWRMP
Task 6: Groundwater
Apolloner, V. and F. Bockmühl (1991). Results of the investigation of groundwater
resources to supply Karasburg.- Geohydrology/DWA/Windhoek: Report 31 pp.
Barbour, E. A. Water supply for road construction Goageb - Aus Road. Proposal for
groundwater investigation.- CBA/Windhoek: Report
Bardenhagen, I. (1998). Final report groundwater exploration for the extension of the Tses
State Water Scheme.- DWA/Windhoek: Report 44 pp.
Bardenhagen, I. (1998). Groundwater exploration for the extension of the Tses State
Water Scheme.- Geohydrology Division, DWA/Report 12/11/2/32, 44 pp.
Bittner, A. (1995). Kalkrand State Water Scheme siting and drilling of standby boreholes.-
Geohydrology/DWA/Windhoek: Report
Biwac (1995). Geohydrological investigation to select drill sites for livestock watering
points
at
the
Gellap-Ost
agriculture
research
station
in
the
Karas
Region.-
Geohydrology/DWA/Windhoek: Report
BIWAC (2001). Applying photo -geological and geophysical methods to select drilling sites
for livestock watering points at the Tsumis Agriculture College drilling and testpumping
results.- BIWAC for DWA/Windhoek: Report
Blom, L. W. R. and A. C. W. Mew (1983). Groundwater potential of the Haris River South
and South-East of Rehoboth.- Geohydrology/DWA/Windhoek: Report
Bockmühl, F. (1988). Verslag oor die ondersoek na aanvullende grondwaterbronne in die
omgewing Aroab.- Geohydrology/DWA/Windhoek: Report 17 pp.
Boye, L. (1990). Verkenningsmemorandum oor die Maltahöhe Staatswaterskema.-
DWA/Windhoek: Report
Carr, R. (1990). Namaland and Bondelswarts 134, Borehole siting programme. Report No.
1 : Desk study.- C. & S. Exploration Company/Windhoek: Report
Carr, R. (1991). Namaland and Bondelswarts 134, Borehole siting programme . Final
report.- C. & S. Exploration Company/Windhoek: Report
Cashman, A. (1986). Planning report on the future bulk water supply to Rehoboth.-
DWA/Windhoek: Report 3120/2/13/P2,
CBA (1994). Drought Relief Management Programme: Hardap Region, Rehoboth Town
lands.- CBA/Windhoek: Report
13/11/2007
Final
63

---

Orange IWRMP
Task 6: Groundwater
CBA (1994). Drought Relief Management Programme: Namaland, Hardap - Karas Region:
Final Report.- CBA/Windhoek: Report
CBA (1994). Namaland Emergency Drought Aid Programme: URG/Nam 793/101 Hardap -
Karas Regions.- CBA for DWA/Windhoek: Report
CDM (undated). SWA Coal project (Aranos Basin).- CDM Mineral Services/Report EG
087,
Christelis, G. (1986). Geohydrological investigation and drilling result at Hobas 374.-
DWA/Windhoek: Report Geohydrology Report 490/11/G1, 10 pp.
Christelis, G. (1987). Ai-Ais State Water Scheme: evaluation of the production potential of
the alluvials in the Fish River.- DWA, Windhoek/Report Geohydrology Report 490/11/4, 23
pp.
Christelis, G. (1987). Ai-Ais SWS evaluation of the production potential of the alluvials in
the Fish River.- Geohydrology/DWA/Windhoek: Report Geohydrology Report 490/11/4, 23
pp.
Christelis, G. (1987). Geohydrological investigation and drilling results at Hobas 374.-
DWA, Windhoek/Report Geohydrology Report 490/11/G1, 10 pp.
Christelis, G. (1987). Geohydrological investigation and drilling results in the vicinity of
Groot Aub in the Rehoboth gebied.- Geohydrology/DWA/Windhoek: Report
Christelis, G. (1987). Geohydrological investigation and drilling results in the vicinity of
Groot Aub in the Rehoboth Gebiet.- DWA, Windhoek/Report Geohydrology Report
3122/9/G4, 20 pp.
Christelis, G. (1991). Re-evaluation of the Fish River alluvials of the Ai-Ais State Water
Scheme.- DWA, Windhoek/Report Geohydrology Report 490/11/G5, 20 pp.
Christelis, G. (1991). Re-evaluation of the Fish river alluvials of the Ai-Ais SWS.- DWA:
Geohydrology Division/Windhoek: Report Geohydrology Report 490/11/G5, 20 pp.
Djama, M. (1995). Aranos State Water Scheme. Memorandum on drilling and
testpumping.- Geohydrology/Windhoek: Report 15 pp. + App.
Djama, M. (1996). Aranos State Water Scheme : Memorandum of drilling and
testpumping.- Report File No. 12/9/2/2, 15 pp. + Appendix.
13/11/2007
Final
64

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Orange IWRMP
Task 6: Groundwater
Djama, M. (1996). Aranos State Water Scheme memorandum on drilling and
testpumping.- Geohydrology/DWA/Windhoek: Report 15 pp.
Djama, M. (1996). Aranos State Water Scheme. Memorandum on drilling and
testpumping.- Geohydrology/Windhoek: Report 15 pp. + App.
Djama, M. (1996). Memo on the preliminary investigation of potential groundwater
resources to supply Mariental with water in the event of failure of the Hardap dam.-
Geohydrology/DWA/Windhoek: Report 9 pp.
DWA (1923-1965). Groundwater investigation Auob Aquifer, DWA.
DWA (1974). Verslag betreffende die artesiese boorgat op ou Stampriet.- DWA - Drilling
Section/Report
DWA (1974). Vorderingsverslag oor afdigtingstegnieke en navorsing in die Stampriet
Artesiese Gebied.- Planning Division/DWA/Report 8 pp, 6 bylaes.
Egerer, E. (1998). Sustainable development of groundwater resources in Southern and
Eastern Africa regional technical co-operation project RAF 8/029.- Report
Forster, P. and A. du Plessis (1988). Planning memorandum on the proposed extension to
the Ai-Ais SWS.- DWA/Windhoek: Report 13 pp.
Forster, P. and A. du Plessis (1988). Planning memorandum on the proposed extension to
the AI-Ais SWS.- DWA/Windhoek: Report
Gerber, A. (1968). Kalkrand : 'n Waterkaart van die ondergrondse waterbronne in die
gebied.- CSIR for DWA/Windhoek: Report
Gerber, A. (1968). 'n Waterkaart van die ondergrondse waterbronne in Suidwes-Afrika,
met spesifieke verwysing na die benuttingswaarde van die water. - 'n Intesive opname van
waterbronne in die basaltgebied Kalkrand.- NIER/CSIR for DWA/Report Project 905, Code
No, 6321/9905, 67 pp.
Gerber, A. (1969). 'n Intensiewe opname van waterbronne in die basaltgebied om
Kalkrand.- CSIR/Windhoek: Report 5,
Gouws, C. (22002). Report on the current situation regarding the abstraction of water for
domestic,
industrial
and
irrigation
purposes
from
the
Orange
River.-
Law
Administration7DWA/Windhoek: Report File 9/3/3/3, 18 pp.
13/11/2007
Final
65

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Orange IWRMP
Task 6: Groundwater
Grobbelaar, J. H. (1986). Result of the Amas 30 day pumping test and a possible strategy
to
supplement
the
Karasburg
State
Water
scheme.-
DWA:
Geohydrology
Division/Windhoek: Report Geohydrology report 480/11/G2, 33 pp.
Grobbelaar, J. H. (1994). Results of the Amas 30 day pumping test and a possible strategy
to supplement the Karasburg State Water Scheme.- DWA: Geohydrology Division/Report
Geohydrology report 480/11/G2,
Groom, B., J. Macgregor, et al. (2002). Sustainable management of the South East
Kalahari Aquifer system, Namibia. Background discussion, management options and
policy recommendations.- Report
Groundwater Consulting Services (1989). Rehoboth State Water Scheme Re-evaluation of
the groundwater resources of the Oanob river in the vicinity of Rehoboth.- Groundwater
Consulting Services/Windhoek: Report 3121/G9/2,
Heath, D. C. (1972). Geologie van die Sisteem Karoo in die gebied Mariental - Asab,
SWA. Pretoria.
Heaton, T. H. E., A. S. Talma, et al. (1980). The age and isotope composition of
groundwater in the Stampriet Artesian Basin, SWA.- NPRL/CSIR/Report Project
400/90615, 20 pp.
HHO Consulting Upgrading of Road on TR 4/1 Between Goageb and Aus -Assessment of
water supply for Construction Purposes.- Report
Hoad, N. (1990). Interim report on groundwater sources supplying Maltahöhe State Water
Scheme.- Geohydrology/DWA/Windhoek: Report 14 pp.
Hoad, N. (1990). Interim report on groundwater sources supplying Maltahöhe State Water
Scheme
Geohydrology report 490/11/G1.- DWA: Geohydrology Division/Report
Huyser, D. J. (1978). 'n Intensiewe opname van waterbronne in die distrik Maltahöhe en
gedeeltes van distrikte Rehoboth en Mariental (Gibeon).- CSIR/Windhoek: Report 16,
Huyser, D. J. (1978). Onverwerkte data versamel tydens 'n intensiewe opname van
waterbronne in die distrik Maltahöhe en gedeeltes van die Distrikte Mariental en
Rehoboth.- CSIR/Windhoek: Report
Huyser, D. J. (1978). P Distrik Maltahöhe, Onverwerkte data.- CSIR/Windhoek: Report 16,
13/11/2007
Final
66

---

Orange IWRMP
Task 6: Groundwater
Huyser, D. J. (1981). M Distrik Rehoboth (sonder Rehoboth gebied), OInverwerkte data.-
CSIR/Windhoek: Report
Huyser, D. J. (1982). Water quality map 1 : 1 000 000 (TDS, SO4, F, NO3). Pretoria,
National Institute for Water Research, Council for Scientific and Industrial Research.
JICA (1999). The study on the groundwater potential evaluation and management plan in
the Southeast Kalahari (Stampriet Artesian Basin in the Republic of Namibia Progress
report (l) Data Book of Existing borehole Survey.- JICA for DWA/Windhoek: Report
JICA (2002). The study on the groundwater potential evaluation and management plan in
the Southeast Kalahari (Stampriet) Artesian Basin in the Republic of Namibia (Final report:
Main report, Executive summary, Supporting report, and Data Book).- JICA for
DWA/Windhoek: Report
Kirchner, J. (1979). Potential report on the groundwater conditions at Aranos.- DWA,
Windhoek/Report Geohydrology Report, 37 pp.
Kirchner, J. (1980). The groundwater potential of the alluvial of the Fish River at Ai-Ais.-
Geohydrology/DWA/Windhoek: Report
Kirchner, J. (1980). The groundwater potential of the Maltahöhe Town lands.- DWA,
Windhoek/Report Geohydrology Report, 3 pp.
Kirchner, J. (1981). Report on the effect of the Otjivero Dam on the recharge of the
groundwater in the Lower White Nossob.- DWA/Report Geohydrology report,
Kirchner, J. and G. Tredoux (1975). The chemical composition of the groundwater with
respect to geological formations. The Stampriet Artesian Basin with special reference to
the Salt Block.- Geological Survey and CSIR/Windhoek: Report
Kirchner, J. and G. Tredoux (1975). The Stampriet Artesian Basin, with special reference
to the salt-block: The chemical composition of the groundwater with respect to geological
formations.- DWA and CSIR/Windhoek: Report
Kirchner, J., G. Tredoux, et al. (2002). The IAEA Stampriet Artesian Basin recharge
project.- Geohydrology/DWA for IAEA/Report RAF 8/029, IV + 66 pp., 6 Appendices.
Kirchner, J., G. Tredoux, et al. (2002). Applying environmental isotopes to a
hydrogeological
model
of
the
Stampriet
Artesian
Basin
Project
RAF
8/029.-
Geohydrology/DWA/Windhoek: Report
13/11/2007
Final
67

---

Orange IWRMP
Task 6: Groundwater
Kirchner, J., G. Tredoux, et al. (2002). International Atomic Energy Agency RAF 8/029.
Sustainable development of groundwater resources in the Africa.
Kruger, J. (1969). Verkenningsverslag watervoorsiening Gochas.- DWA/Windhoek: Report
22 pp.
Kruger,
J.
(1969).
Verkenningsverslag:
Watervoorsiening
Gochas.-
Planning
Division/DWA/Report
Lindgren, A. (1999). The value of water - A study of the Stampriet Aquifer in Namibia.
Low, D. (2000). An overview of the drilling programme in the Blumfelde area of
the
Southeast Kalahari (sub) - Artesian Basin to collect groundwater samples for isotope
analysis applying the EDL- Technology.- Geohydrology/DWA/Windhoek: Report
Lukowski, G. J. (1989). Verkenningsmemorandum oor Grünau Staatwaterskema.-
DWA/Windhoek: Report
Mew, A. C. M. (1980). Watervoorsiening: Groot Aub School, Distrik Rehoboth.- DWA:
Geohydrology Division/Report Geohydrological report 3122/G167/3,
Mew,
A.
C.
W.
(1974).
Boorplekaanwysings
Namaland
Itzawisis
area.-
Geohydrology/DWA/Windhoek: Report
Mew, A. C. W. (1976). Boorplekaanwysings: Grünau dorp en Chamities deca navigasie
stelsel.- Geological Survey/Windhoek: Report
Müller, S. (1992). Aranos State Water Scheme : Memorandum on drilling and
testpumping.- Report File 19/9/2/2, Geohydrology, DWA13 pp.
Müller, S. (1994). Aranos State Water Scheme: Memorandum on drilling and
testpumping.- DWA: Geohydrology Division/Report
Müller, S. (1994). Gobabis State Water Scheme: Groundwater source potential
and
proposal for further investigations.- DWA: Geohydrology Division/Report
Nawrowski, J. Locality of the Salt Block, deeper groundwater sources underlying the salt
block of the basin.- Geohydrology/Windhoek: Report 9 pp.
Nawrowski, J. (1986). Progress report No.1 on the Stampriet Artesian Basin (Results of
the
b/h
survey
within
the
Stampriet-Gochas
area).-
DWA:
Geohydrology
Division/Windhoek: Report Geohydrological report 3100/9/G21,
13/11/2007
Final
68

---

Orange IWRMP
Task 6: Groundwater
Nawrowski, J. (1986). Progress report No. 1 on the Stampriet Artesian Basin: Results of
the
borehole
survey
within
the
Stampriet-Gochas
area.-
DWA:
Geohydrology
Division/Report Geohydrological report 3100/9/G21,
Nawrowski, J. (1987). Progress report No.2 on the Stampriet Artesian Basin (Result of the
b/h survey within the Aranos-Leonardville area).- DWA: Geohydrology Division/Windhoek:
Report Geohydrological report 3100/9/G22,
Nawrowski, J. (1987). Progress report No. 2 on the Stampriet Artesian Basin: Results of
the
borehole
survey
within
the
Aranos-Leonardville
area.-
DWA:
Geohydrology
Division/Report Geohydrological report 3100/9/G22,
Nawrowski, J. (1987). Some notes on the Geohydrology and Hydrochemistry of the Salt
Block within the Stampriet Artesian Basin.- DWA - Geohydrology/Windhoek: Report
3100/9/621, 9 pp.
Nawrowski, J. (1989). Progress report No.3 on the Stampriet Artesian Basin (Result of the
b/h
survey
in
Area
3,
the
North-western
intake
area).-
DWA:
Geohydrology
Division/Windhoek: Report Geohydrological report 12/9/G3,
Nawrowski, J. (1989). Progress report No. 3 on the Stampriet Artesian Basin: Results of
the borehole survey in area 3, the northwester intake area.- DWA: Geohydrology
Division/Report Geohydrological report 12/9/G3,
Nillson, A. and L. Sahlen (2002). Lucerne or Grapes - A question of water pricing - An
estimation of the value of irrigation water used at the Hardap Scheme, Namibia.
Plathe, D. J. R. (1978). The surface water potential of various dam sites in Namaland.-
Hydrology/DWA/Windhoek: Report
Seeger, G. (1969). Voorlopige verslag oor die waterontwikkeling vir 'n gebied tussen die
Swart Nossobrivier en Klein Aub koppermyn.- Geological Survey/Windhoek: Report
Smalley, T. (1995). Inception report for hydrogeological work in the Hardap and Karas
Regions.- Interconsult/Windhoek: Report
Tredoux, G. Onverwerkte data versamel tydens 'n intensiewe opname van waterbronne
noordoos van Keetmanshoop.- CSIR/Windhoek: Report 11,
Tredoux, G. (1970). 'n Intensiewe opname van waterbronne in die gebied om Warmbad.-
CSIR/Windhoek: Report 6,
13/11/2007
Final
69

---

Orange IWRMP
Task 6: Groundwater
Tredoux, G. (1971). Intensiewe opname vann waterbronnne in die in die Soutblok gebied.-
CSIR/Windhoek: Report
Tredoux, G. (1971). n Waterkaart van die ondergrondse waters in Suidwes -Afrika met
spesifieke verwysing na die benuttingswaarde van die water. intensiewe opname van die
waterbronne in die Soutblock projekverslag No. 7.- CSIR/Windhoek: Report 7,
Tredoux, G. (1971). 'n Waterkaart van die ondergrondse waters in SWA met spesifieke
verwysings na die benuttingswaarde van die water. Onverwerkte data ingesamel
gedurende n opname in die Saltblok.- CSIR/Windhoek: Report 7,
Tredoux, G. (1972). 'n Intensive opname van waterbronne in die suidoostelike hoek van
Suidwes-Afrika.-
CSIR
vir
37ste
vergadering
van
die
Loodskomitee
vir
Waternavorsing/Windhoek: Report 8,
Tredoux, G. (1972). Onverwerkte data versamel tydens n intensiewe opname van
waterbronne in die suidoostelike hoek.- 37ste vergadering van die Loodskomitee vir
Waternavorsing/Windhoek: Report
Tredoux, G. (1972). Onverwerkte data versamel tydens n intensiewe opname water
Soutblok.- CSIR/Windhoek: Report
Tredoux, G. (1973). 'n Intensiewe opname van waterbronne in die suidelike deel tussen
17° en 18.30° O.L suid van 26.30° S.B.- CSIR/Windhoek: Report 9,
Tredoux,
G.
(1973).
'n
Intensiewe
opname
van
waterbronne
in
Namaland.-
CSIR/Windhoek: Report 10,
Tredoux, G. (1973). Onverwerkte data versamel tydens 'n intensiewe opname van
waterbronne in die suidelike deel tussen 17° en 18.30° O.L en suid van 26.30°.-
CSIR/Windhoek: Report
Tredoux, G. (1973). Onverwerkte data versamel tydens 'n intensiewe opname van
waterbronne in Namaland.- CSIR/Windhoek: Report
Tredoux, G. (1975). N Distrik Lüderitz: Onverwerkte data.- CSIR/Windhoek: Report
Tredoux, G. (1975). 'n Intensiewe opname van waterbronne in die distrikte Lüderitz and
Bethanie.- CSIR/Windhoek: Report 13,
Tredoux, G. (1975). 'n Intensiewe opname van waterbronne in die Rehoboth gebied.-
CSIR/Windhoek: Report 14,
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Task 6: Groundwater
Tredoux,
G.
(1975).
'n
Intensiewe
opname
van
waterbronne
noordoos
van
Keetmanshoop.- CSIR/Windhoek: Report 11,
Tredoux, G. (1975). Onverwerkte data versamel tydens 'n intensiewe opname van
waterbronne in die distrik Rehoboth.- CSIR/Windhoek: Report
Tredoux, G. (1975). Onverwerkte data versamel tydens n intensiewe opname van
waterbronne in die Lüderitz en Bethanie distrikte.- CSIR/Windhoek: Report 13,
Tredoux, G. (1975). S Distrik Bethanie: Onverwerkte data.- CSIR/Windhoek: Report
Tredoux, G. (1977). 'n Intensive opname van waterbronne in die Artesiese Gebied
Stampriet.- CSIR/Windhoek: Report 15,
Tredoux, G. (1977). Onverwerkte data versamel tydens 'n intensiewe opname van
waterbronne in die Artesiese gebied Stampriet.- CSIR/Windhoek: Report
Tredoux, G. (1977). R Distrik Mariental (Gibeon):Onverwerkte data.- CSIR/Windhoek:
Report
Tredoux, G. (1977). T Distrik Keetmanshoop (onverwerkte data).- CSIR/Windhoek: Report
Tredoux, G. (1981). Die korrelasie tussen waterkwaliteit en geologiese formasie in SWA ['n
Geohidrochemiese ondersoek van die Artesian Kom Stampriet]. Bloemfontein, UOVS.
Tredoux, G. (1999). The study of the groundwater potential evaluation and management
plan in the Southeast Kalahari (Stampriet) Artesian Basin in the Republic of Namibia Task
11: Initial Environmental Examination.- CSIR/Stellenbosch: Report
Tredoux, G. (2000). International Atomic Energy Agency (IAEA) Project: RAF 8/029
Sustainable development of groundwater resources Task 13: Data evaluation and training
report
on
Expert
Mission
to
Namibia:
25
September
to
6
October
2000.-
CSIR/Stellenbosch: Report
Tredoux, G. (2000). Report on Expert Mission to Namibia: 25 September to 6 October
2000.- CSIR/Stellenbosch: Report
Tredoux, G. and J. Kirchner (1979). Die Geohidrologie van die Artesiese Kom Stampriet.-
Geol. Survey and CSIR/Windhoek: Report
Tredoux, G. and J. Kirchner (1981). "The evolution of the composition of Artesian in the
Auob sandstone." Trans. geol. Soc. S. Afr. 84: 169-175.
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Task 6: Groundwater
Tredoux, G., J. C. Vogel, et al. (1978). Die Geohidrologie van die Artesiese Kom
Stampriet, met inagneming van die chemie en die isotopesamestelling van die waters. Part
III: Data.- CSIR & Geol. Survey/Windhoek & Pretoria: Report
Tredoux, G., J. C. Vogel, et al. (1979). Die Geohidrologie van die Artesiese Kom
Stampriet. PART II: Maps.- CSIR & Geol. Survey/Windhoek: Report
van Langenhove, G. and J. Church (1989). The potential for the release of water for
ecological purposes from the Oanab Dam.- Hydrology/DWA/Windhoek: Report 3121/2/H3,
43 pp.
van Vuuren, O. (1991). Rehoboth State Water Scheme: Possible potential and reserves in
the downstream compartment in the Oanob River.- Geohydrology/DWA/Windhoek: Report
van Vuuren, O. (1991). Water supply to Karasburg: testing of the Amas aquifer.-
Geohydrology/DWA/Windhoek: Report
van Vuuren, O. (1992). The development of additional water sources to supplement the
Schlip State Water Scheme.- Geohydrology/DWA/Windhoek: Report
Van Vuuren, O. (1997). Pumping test evaluation : Westfalen.- Report
van
Vuuren,
O.
(1997).
Testpumping
at
Westfalen.(Ref.03/004/ovv.-
Consulting
Geohydrologist/Windhoek: Report
van Wyk, W. L. and L. W. R. Blom (1968). Decca Project : Water Supply at Noordoewer.-
Report
Vogel, J. C., A. S. Talma, et al. (1980). The age and isotope composition of groundwater in
the Stampriet Artesian Basin, SWA.- NPRL/CSIR/Report 49 pp.
Vogel, J. C., A. S. Talma, et al. (1982). The age and isotope composition of groundwater in
the Stampriet Artesian Basin, SWA.- NPRL/CSIR/Report Project 400/90615, 49 pp.
Vogel, J. C., A. S. Talma, et al. (1982). The age and Isotopic composition of the
groundwater in the Stampriet Artesian Basin, SWA. (Final report to the Steering
Committee of Water Research).- NPRL/CSIR/Pretoria: Report
Vogel, J. C. and H. Van Urk (1977). Isotoopsamestelling van die grondwater in die
Stampriet Artesiese Kom.- Report Project No. 400/90185, 5 pp.
Vogel, J. C. and H. Van Urk (1977). Isotopesamestelling van die grondwater in die
Artesiese Kom Stampriet.- CSIR/Pretoria: Report
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Vogel, J. C. and H. Van Urk (1979). Isotopesamestelling van die grondwater in die
Artesiese Kom Stampriet.- CSIR/Pretoria: Report
Wilson,
E.
J.
(1964).
Vreda
R281
No.
1
(Stratigraphic
test).-
Artnell Exploration Company/Report
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4
LESOTHO GROUNDWATER OVERVIEW
4.1
Introduction
Groundwater resources have played a crucial role in water supply for both rural villages
and urban centres in Lesotho. Use of developed and undeveloped springs as well as
handpumps, high capacity production boreholes and river abstraction (Senqu / Orange)
systems
are
all
somewhat contingent
upon
groundwater
supplies.
Beyond
the
Geohydrology and subsurface environment the quantity and quality of Lesotho's
groundwater resources are of critical interest in the planning and management within the
water sector in general, but particularly for the ORASECOM Integrated Water Resources
Management Plan.
Figure 4-1: Locality map of Lesotho
The groundwater resources of Lesotho have been examined in various studies, primarily
beginning in the early 1970s. Historically, the dominant use of surface water for town
supplies and naturally occurring springs for rural village supply did not necessitate detailed
examination of groundwater occurrence and availability. However, with the rapid growth
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within the Senqu (Orange) River Basin, dependence on groundwater resources has
expanded greatly. Furthermore, as the need for reliable year-round sources for towns
becomes an increasing priority, several towns have augmented river abstraction systems
with the conjunctive use of groundwater from boreholes and wellfields.
The water requirements of the once growing number of textile manufacturing companies in
Lesotho was partially met from groundwater sources, and given the current (January 2005)
unclear future of these entities and the projected future water demands for such industries,
groundwater would be able to provide a significant proportion of water supply to meet said
demand. The importance of groundwater to the national economy must not be ignored,
and requires effective resource evaluation, planning and management. At present, the
Ministry of Natural Resources (MoNR) through the DWA, DRWS and WASA controls
groundwater development in Lesotho.
4.1.1
The Department of Water Affairs (DWA)
The Groundwater and Water Pollution Control Divisions of DWA are responsible for
groundwater exploration, management and resource assessment at national and district
level. This includes the monitoring of groundwater abstraction and water quality
assessment of groundwater vulnerability to pollution, as defined by the Water Resources
Act of 1978. Groundwater development is regulated by DWA; facilitated by DRWS and
WASA; designed and supervised by consultants; implemented by contractors; and funded
by
international
donors.
The
principle
hydrogeologist
and
his
small
team
of
hydrogeologists forming the Groundwater Division (GWD) are the only qualified
hydrogeologists in Government service. DWA has a good library of project reports.
4.1.2
The Department of Rural Water Supplies (DRWS)
DRWS formerly implemented rural groundwater supply projects using contractors to install
spring fed gravity systems and handpump or motorised pump equipped boreholes for
domestic supply. Since an evaluation of the function of DRWS in 1996, the Department
has, with the assistance of Helvetas, a Swiss NGO, changed role from that of implementer
to facilitator. During 1998-2002 DRWS adopted the demand response approach to rural
community water supply provision assisting communities to make informed choices about
water supply systems, facilitating their active involvement in planning, installation and
operation and maintenance (O&M) activities thus enabling community ownership of the
systems. Whether this has happened in practice, needs to be determined.
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In addition to the Head Office in Maseru, DRWS has three regional and ten district offices.
DRWS rely upon DWA and consultants for professional hydrogeological expertise. DRWS
water engineers supervise the installation of boreholes, spring supplies gravity fed
systems and other distribution systems. Rural groundwater development projects are
funded and supported technically by various donor agencies. DRWS currently supplies
water to 60% of the rural population of which two thirds comes from spring-supplied gravity
fed schemes, and the remaining third from boreholes equipped with handpumps or
submersibles. Summary borehole data sets are held in a digital database at headquarters,
with detailed borehole and supply system data held at district level in hard copy files.
4.1.3
Water and Sewage Authority (WASA)
WASA is responsible for water supply and sanitation in the 13 urban areas of Lesotho.
Mazenod does not have a WASA water reticulation system. In Butha-Buthe, Hlotse,
Mapoteng, Maputsoe, Mohale's Hoek, Morija, Peka, Quthing, Roma and Teyateyaneng
surface water sources are supplemented by groundwater from high yielding boreholes or
river intakes. The Maseru and Mafeteng water reticulation schemes are supplied from
surface water. WASA has a good library of project reports.
4.1.4
The Department of Mines
The Department of Mines includes the Geological Survey of Lesotho that formerly included
a groundwater development division. Their library holds copies of most of the records of
early groundwater development undertaken during 1960-1980 in Lesotho. The Department
of Mines has a library on the geology of Lesotho that is the source of all geological maps
for Lesotho.
4.1.5
Consultants
Groundwater Consultants BeePee (Pty) Ltd (GWC) is the main hydrogeological consultant
in Lesotho. It, in association with several international consultants, has been responsible
for site surveys, borehole design and construction and testpumping of wellfields installed
for most of Lesotho's townships. GWC has a library of groundwater related reports, a
database and in-house hydrogeological experience in Lesotho. They prepared the
Geohydrology and Groundwater resources chapter of the TAMS (1996) report. Sechaba
Consultants of Maseru undertook various sociological baseline surveys as part of the
TAMS 1996 study including a survey of the location and status of rural community water
sources.
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4.2
Geohydrology of Lesotho
Within the Senqu / Orange River Basin in Lesotho, groundwater occurs within the fractured
Karoo Supergroup sedimentary and basalt rock aquifers, alluvial sediments and within
fracture and dolerite intrusion zones. The variable occurrence of groundwater is illustrated
by borehole yields that vary from dry (seepage) to up to 8.0 litres/sec within a few metres
of a dolerite intrusion. What little is understood of the hydrogeological and hydraulic
characteristics of these aquifers has been derived from analysis of the National
Groundwater Database of borehole records compiled by TAMS (1996). No attempt has
been made to assess the composition, porosity and permeability variations within the
aquifers using plugged core samples of the rock formations. The quality of groundwater is
thought to be good but hydrochemical analyses are few and far in number and limited to
major ions and some trace elements. Fluoride has been determined as occurring at levels
potentially harmful to health at a small number of sites.
4.2.1
Burgersdorp Formation Geohydrology
This mainly argillaceous formation has low productivity with borehole yields of less than
0.5 litres/sec. Boreholes drilled adjacent to dolerite intrusions, especially ring dykes, tend
to display higher yields of 1-2 litres/sec obtained from baked sediments. An average
borehole yield for the Burgersdorp Formation is 1.6 litres/sec, reflecting the large number
of boreholes drilled adjacent to dolerite intrusions. The average borehole depth is 59m and
average depth to water table is 22m. Average transmissivity of 20m2/m/d and storativity of
0.00117 indicate semi-confined to confined conditions within a low permeability aquifer.
4.2.2
Molteno Formation Geohydrology
The Molteno Formation sandstone aquifer has good groundwater development potential.
The quality of this aquifer varies according to the sand / shale ratio and degree of
cementation of the component sandstone layers. This aquifer has been developed at
Roma and Teyateyaneng where wellfields with individual yields of greater than 3 litres/sec
have been installed. The total recommended yield for the Roma wellfield is 21 litres/sec
(75.6m3/hr) and that of Teyateyaneng wellfield is 22 litres/sec (79.2m3/hr).
The Molteno aquifer can have both limited primary intergranular permeability as well as
secondary fracture permeability. The most productive boreholes are located adjacent to
dolerite dykes where secondary permeability has been developed by the baking and
jointing of the formation during periods of contact metamorphism. Other productive
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boreholes have been located in well-developed fracture zones unrelated to intrusions
(Groundwater Consultants 1992, 1995). The Molteno outcrops also form an important
spring line with individual spring discharges as high as 0.5 litres/sec. Statistical analysis of
available borehole data suggest an average borehole yield in the Molteno aquifer of 1.6
litres/sec, average borehole depth of 61m and average depth to water table of 24m.
Average transmissivity of 20m2/m/d and storativity of 0.001 are indicative of a low
permeability aquifer under semi-confined groundwater conditions.
4.2.3
Elliot Formation Geohydrology
Within the Elliot Formation groundwater mainly occurs within the interbedded sandstone
layers that show significant lateral variability in thickness. Drilling and testpumping data
analyses indicate that the Elliot Formation is often in hydraulic continuity / connectivity with
the underlying Molteno Formation. Water strikes are often recorded during the drilling at
the contact between these formations. Analysis of available Elliot Formation borehole data
indicate an average borehole yield of 1.3 litres/sec, an average borehole depth of 60m and
an average depth to water table of 27m. Average transmissivity of 24m2/m/d and storativity
of 0.0005 indicate the Elliot Formation has low permeability under confined conditions and
with less development potential that the Molteno or Burgersdorp Formations.
4.2.4
Clarens Formation Geohydrology
The Clarens Formation is composed of compact sandstones with poor aquifer qualities.
Important spring zones occur and the Lesotho basalt ­ Clarens sandstone contact and at
the upper sandstone ­ siltstone junction with the main Clarens Formation. Analysis of
borehole data from this formation gave an average borehole yield of 0.9 litres/sec, an
average borehole death of 62m and an average depth to water table of 28m. The average
transmissivity of 5m2/m/d indicates a low permeability aquifer.
4.2.5
Lesotho Formation Basalts Geohydrology
In the highland areas (headlands of the Senqu / Orange River) numerous springs occur at
all levels mainly from weathered basalt horizons at the inter-basalt flow zones and
adjacent to dolerite dykes. Some of the few boreholes drilled into this formation have high
yields, with water strikes occurring in the weathered mantle, at inter-flow zones and in
dykes and fracture zones. In the Likalaneng area water strikes have been recorded at
depths greater than 150m with blow yields exceeding 10 litres/sec. The limited borehole
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data gave an average borehole yield of 2.6 litres/sec, an average borehole depth of 66m
(due to deeper water strikes in precipitous and mountainous topography).
4.2.6
Dolerite Dykes and Fracture Zones Geohydrology
Analysis of testpumping data from boreholes drilled into and adjacent to dykes suggest
that, although permeable, the storage capacities of dyke zones are generally low.
Therefore, although the presence of a dyke may greatly improve hydraulic conductivity, the
storage potential of the country rock should define the yield and drawdown characteristics
of the production borehole. A borehole sited in a dyke zone in the Molteno aquifer will be
more productive than one located in a dyke zone in the Elliot aquifer.
4.2.7
Alluvial Sediments Geohydrology
The Quaternary and Recent alluvial aquifers have good hydraulic characteristics although
their size is limited. The hydraulic characteristics are variable and often site specific,
making borehole siting difficult. Some of the largest deposits of exploitable alluvial aquifers
are in the Maputsoe wellfield area, in the area around Butha Buthe, north of Teyateyaneng
and near Mazenod. Water is abstracted from these alluvial sediments using well point or
gallery systems. Analysis of testpumping data results from the Maputsoe wellfield
indicated a potential yield of 40 litres/sec when first developed. Similarly, the testpumping
of boreholes installed to supply Butha Buthe Township have been installed in Quaternary
and Recent age alluvial sedimentary aquifers with potential borehole yields of 1.5 to 4.0
litres/sec. An open well sunk in Mohale's Hoek produces 3 litres/sec for the town's water
supply system.
Analysis of borehole testpumping data from alluvial deposits gave an average depth to
water table of 15m and an average borehole depth of 41m. Both of these parameters
reflect the generally shallower nature of these aquifers compared to bedrock aquifers. The
average transmissivity is 106m2/m/d, indicative of the significant primary porosity. An
average storativity of 0.04 suggests unconfined and semi-confined aquifer conditions.
4.3
Hydrogeological Data Availability and Procedures
A range of hydrogeological data is required for the estimation of groundwater resources
and associated aspects of resource development and management. These data have
been and should be acquired during each stage of the resource development. The data
types available, their sources and format and their collection procedures in Lesotho (but
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certain aspects apply to the Basin Member Countries ­ SADC Groundwater Protocol) are
outlined below.
4.3.1
Borehole Siting
Fine grained and compact sedimentary rocks with low intrinsic permeability underlie the
western Lowlands region of Lesotho. The optimum sites for water well drilling are located
accurately on zones of fracturing and contact metamorphism adjacent to dolerite dykes
where groundwater occurrence is enhanced by patterns of intense joining and weathering.
Information obtained from surveys of such sites include:
· Location of geophysical surveys and proposed drilling sites located using GPS or
grid reference from a 1:50 000 scale topographic map
· Analysis of data from geophysical surveys to indicate dyke attitude, as well as the
thickness of the dyke, the baked zone of contact metamorphism and weathered
zone
· Descriptions of the local surface geology, topography and patterns of drainage
· Location and use of existing points of water abstraction such as boreholes, rivers
and springs
DWA teams are able to locate borehole drill sites using geophysical survey equipment (not
defined) donated by a Japanese funded project undertaken in 1996-7. Geophysical
equipment (not defined) left by the Italian Groundwater Project cannot be used due to lack
of trained staff.
DRWS technicians formerly located borehole-drilling sites using aerial photography and
geological maps. During 1994 they also used magnetic geophysical surveys for drill site
location.
Currently, consultants locate new borehole sites on fracture and dyke zones
using data from interpretation of aerial photographs, geological maps and field geophysical
surveys. Geophysical methods used to locate drilling targets include magnetic traversing,
electromagnetic survey traversing and resistivity vertical electrical soundings (VES).
Geophysical survey and drilling sites should be accurately located using a geographical
positioning system (GPS) and 1:50 000 scale topographic maps. The geophysical survey
data and interpretations should be reported. Where professional borehole siting expertise
is absent, drilling contractors use dowsing with geological and visual inspection to locate
drilling sites (dowsing should not be encouraged).
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Although a good density of boreholes and detailed geological maps (may) exist, data
crucial for hydrogeological assessments such as thickness of weathered zones, lithology,
colour changes and water strike/loss zones are rarely recorded. Thick surficial weathered
zones often mask the solid geology. Lithological data collected during borehole drilling are
needed for assessment of hydrogeological characteristics and lack of these data sets
clearly needs to be addressed. Institutions responsible for drilling boreholes should ensure
the collection of representative geological and hydrogeological samples to be examined
under laboratory conditions, especially where boreholes are drilled in marginal areas.
These data are needed for groundwater resource assessment at district or sub-district
level. Production borehole design is dependant upon the following :
· Type and dimensions of borehole pump
· Yield/drawdown characteristics of the borehole
· Available drilling method
· Depths of water strike zones
· Static water level variations
· Geology of the aquifer formation
· Access for water level monitoring equipment
With decentralisation of rural water supply and greater involvement of NGOs, there has
been a tendency to use minimum standards of construction to reduce the borehole
installation costs. Community borehole ownership can only be ensured if they can afford
to contribute a realistic proportion of the cost of borehole installation, operation and
maintenance. The use of minimum diameter borehole components results in access of
water level measuring equipment being sacrificed.
Information required to be collected during borehole drilling that will inform borehole
construction includes:
· Description of the drilling method, drilling system equipment and capacities
· Accurate location of the borehole drilling site, including village name and GPS
location
· Dates of start and completion of drilling and construction
· Drill penetration rate with bit types and sizes as well as borehole flushing medium
per metre including the addition of foam
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· Collection of formation chip samples and their lithological description (including
colour) at 1m intervals. The samples should be placed in sequence along a
sectioned half tube and photographed with a digital camera to record colour
change with depth. In unconsolidated alluvial materials disturbed samples of at
least 1 kg/m should be obtained for grain size analysis especially from water
producing zones
· Depths of water strike and water loss with determination of water flow by airlift at
3m intervals
· Details of all components used in borehole construction including types and
lengths of casing and screen with coupling types, materials and dimensions, slot
sizes, zones of grouting and gravel packing (grain size and source of pack
material)
· The above information is needed for borehole design and for recognition of
causes of problems resulting from borehole operation
Most boreholes installed for DWA, DRWS and WASA are now drilled using rotary air flush
down-the-hole-hammer equipment and generally only private boreholes are drilled using
cable tool percussion equipment. Except for DWA exploration boreholes, all production
boreholes are drilled, constructed and test pumped by drilling contractors who are required
to complete DWA standard borehole completion forms.
During 1982-1992 the DRWS installed nearly 6000 low capacity boreholes, most equipped
with handpumps and a few with submersible pumps. These boreholes were mainly drilled
to depths of 40 to 100m with a few as deep as 120m and the occasional borehole drilled to
more than 150m. While the older boreholes of the pre 1980 period were drilled using
DRWS cable tool percussion rigs, those installed during the last 20 years were drilled
using the down-the-hole-hammer drilling system.
4.3.2
Aquifer Sustainability and Hydraulic Parameters
Although aquifer testpumping seems to be undertaken at each borehole site, little
understanding of the true meaning of the transmissivity and storage parameters is
achieved from analysis of testpumping data.
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Where boreholes have been drilled into fractured low permeability aquifers (preferably into
fractures, weathered dykes and associated baked zones of contact metamorphism) the
methods of testpumping data analysis employed is not strictly applicable. Most of the
groundwater abstracted at such sites is derived from the linear zone of relatively high
permeability. With prolonged abstraction, even at the low discharge rates experienced
using handpumps, such aquifers can be dewatered over a period of several years if there
is no active recharge from a source such as the bed of a perennial river. Otherwise, during
the dewatering, some water slowly seeps from the surrounding low permeability rocks into
the linear feature at a rate much less than that of abstraction. In the absence of water level
monitoring, the reduction in resources will be noticed belatedly by a reduction in discharge
rate, making handpump operation more difficult. This often leads to the failure of the
borehole that is commonly recognised as being due to pump failure rather than the
dewatering of the aquifer.
Therefore, some information on the distribution of relative permeability and porosity in the
country rocks and within the fracture zone needs to be obtained. In such low permeability
fractured aquifer systems, flow contributions from fractures determined using packer tests
and flow logging with intrinsic permeabilities and porosities of the rock unit determined
using formation core sample tests help determine the sustainability of a boreholes yield.
However, significant understanding of the nature of groundwater flow patterns within a
fractured aquifer can only be obtained from observations made during borehole drilling at
the wellhead.
4.4
Groundwater Data Collection
Data collection procedures in Lesotho remain clearly poor. In 1996 only four to five percent
of borehole records contained yield data and only 1 to 3% had transmissivity and
storativity data (TAMS 1996). This situation does not appear to have changed.
Improved data collection during new DWA projects is being practiced by consultants
during borehole siting, drilling, and construction and testing. Data collected during non-
DWA groundwater projects are not being submitted to the Groundwater Section. A
standard form for collection of drilling, construction and testpumping data has been
produced by DWA based upon data input requirements of the WISH groundwater
software, but its use is limited to the DWA. DRWS used borehole completion forms
produced by the Department of Water Affairs and Forestry of South Africa. Although
comprehensive, they are usually completed by drillers recording little meaningful data.
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DRWS is now planning to use the DWA forms for future borehole drilling programmes.
Although data collection by consultants during WASA and DRWS programmes meets
acceptable standards, only worked data are presented in project reports, raw data are not
passed to DWA. Hence there are usually insufficient data for hydrogeologists to assess
groundwater occurrence, aquifer resources or aquifer sustainability.
4.5
Data Storage and Retrieval
The comments made in this section applies equally well to all the other countries
addressed in this report (Namibia, Botswana and South Africa). The pattern of
groundwater resource development in Lesotho is typical of that observed with the Orange
River Basin Member countries (they all fall within the SADC Region and thus should
adhere to the SADC Groundwater Protocols). The style of resource development is
dependant on :
· The experience of the government department
· The controls of the international donors
· The type of natural disaster that, maybe, is impacting upon groundwater (e.g.
drought)
Aid donors tend to import high cost, high technology solutions such as groundwater
information systems that cannot be locally maintained after project support has ceased.
Unfortunately, data sets collected during such projects can end up locked into software
systems that cannot be accessed without new software and/or dongles designed to limit
access in the first instance. Therefore, it is important that raw data are stored in readily
retrievable spreadsheets that can be imported into any newly introduced GIS systems and
in paper files as hard copy. The data units used in the spreadsheets and GIS systems
must be clearly recorded. There is also a need to record point source geo-referenced data
that can be imported for spatial analysis into a groundwater information system.
4.5.1
Digital and Hardcopy Data
Groundwater data were found to be available on hard copy paper datasheets at DWA
(Maseru) and DRWS (Maseru and Mafeteng), hardcopy reports and maps in the libraries
of DMG (Maseru), DWA (Maseru) and WASA (Maseru) and electronic databases at DWA
(Maseru), at DRWS (Maseru and Mafeteng), at Sechaba Consultants (Maseru) and at
GWC in Maseru. There are four main groundwater database sets. These are discussed in
below.
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4.5.2
DWA / Italian Programme
The groundwater division of DWA maintains a national groundwater database, initiated in
1982 at the start of an Italian funded national groundwater exploration development project
(The Groundwater Programme). This database probably contains geological and borehole
construction logs, testpumping data, hydrochemical data but it is difficult if not downright
impossible to access.
4.5.3
DRWS
The DRWS provides data from boreholes drilled for rural water supply in the National
Database (NDB). The NDB is an administrative database listing information such as village
name, borehole depth, handpump type and installation information. Although it is the
largest database of borehole and spring data, the NDB lacks technical data such as geo-
referenced
co-ordinates,
geological
logs,
borehole
yield,
testpumping
data
and
hydrochemistry. Some of these data are held in paper files at district level. Some geo-
referencing of boreholes was done as part of the TAMS / GWC study, Data held in
hardcopy paper files at the Maseru DRWS divisional office were destroyed in a recent fire.
4.5.4
TAMS
The DWA / Italian project database was modified and expanded in 1996 by TAMS to
contain 8070 (?) records of which about 70% have been geo-referenced. The database is
in dBase IV format and is fully compatible with the Arcinfo based GIS system created
during the project. Although this database can be imported into Access and thereby
transformed into a series of component Excel spreadsheets, it has sadly not yet been set
up for continued use and easy updating of records.
4.5.5
DWA / WISH
Data obtained from projects implemented by DWA after 1996 are, for some reason,
maintained separately by the Groundwater Division within a WISH based GIS using
software from the University of Bloemfontein. Unfortunately, the raw data cannot be
extracted from this database system without the necessary proprietary software.
4.5.6
Relevant Literature
Listings of groundwater related reports held by DWA and GWC were compiled for the
TAMS study. These listings form the basis of the bibliography compiled by Ambrose
(2001) and also form part of the Appendix. These listings need to be updated and listings
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held by WASA and Sechaba compiled. These bibliographies could then be used to
produce a comprehensive listing of all local consultant and departmental groundwater
related reports produced in Lesotho for not only the Senqu River, but for the whole country
in general. The consultant's reports that form the main source of raw and interpreted
groundwater data from wellfields with the Senqu River Basin include :
· Binnie Shand (1977) ­ The Twelve Towns Project
· Groundwater Consultants (1995) ­ Leribe
· Groundwater Consultants (1995) ­ Maseru
· Groundwater Consultants (2000) ­ The Six Towns Project
· Johnstone (1991) ­ Alluvial aquifers at Mashoehoe International Airport
· Lahmeyer (1992) ­ Maseru
· Riemeyer (1988) ­ The Two Towns Project
· WEMMIN (1988) - Maputsoe
Earlier reference lists have been compiled during studies undertaken by Binnie Shand
(1971) and TAMS (1996). Further data sets are recorded within the 130 technical reports
produced during the Groundwater Programme. Hardcopy topographic, hydrogeological
and geological maps of Lesotho are available. The first hydrogeological map of Lesotho
produced by Mott MacDonald (1990) at a scale of 1:250,000 is difficult to access.
The second national hydrogeological map produced by the Italian led Groundwater Project
by Arduino, Bono and Del Sette (1994) at a scale of 1:300,000 can be obtained from the
Department of Water Affairs library. Geological maps of Lowland Lesotho at scales of
1:50,000 and 1:100,000 can be obtained from the Department of Mines and Geology.
Maps depicting the locations of village boreholes are held at DRWS district offices.
4.6
Groundwater Resource Evaluation
TAMS (1996) estimated the renewable groundwater resources of Lesotho to be 10.84m3/s
(cumecs), of which 7.37m3/s is available in the Lowland areas of the basin. Water balance
studies indicate 2.5% of annual rainfall recharges to groundwater systems. There is
unfortunately no water-level data to support these estimates. It is recommended that a
series of digital hydrogeological parameter data layers, created with GIS, should be used
to show:
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· The distribution of the aquifers
· The distribution of aquifer parameters
· The interaction of surface and groundwater with vulnerability to change
· Aquifer recharge potential (and groundwater harvest potential)
· The vulnerability of aquifers to pollution
· The effects of prolonged drought
4.6.1
Hydrogeological Map
Data sets obtained from water supply boreholes and other relevant sources have been
collated in the national geological map to produce hydrogeological maps of Lesotho.
These maps are not yet available in digital format but Lesotho, in common with the other
Basin Member Countries (and SADC), has been asked to produce a digitised national
hydrogeological map as a component of the proposed hydrogeological map of the SADC
region.
4.6.2
Potential Aquifer Recharge and Harvest Potential Map
Although recharge to groundwater forms an integral part of the complex hydrological cycle,
rates and patterns of aquifer recharge and harvest potential are difficult to determine.
None of the methods of recharge evaluation used in Southern Africa is readily applicable
or reliable. Determination of recharge data remains a research topic rather than a
groundwater management and development tool in Lesotho in particular, and it is
suggested potential solutions are workshopped and resolved at some not too distant
stage. Methods of estimating groundwater recharge include water balance, chemical
isotope and long-term level change studies. In South Africa, the results of regional
recharge studies were used to produce a tentative recharge potential map. Such map of
potential recharge should be produced for Lesotho using base-line data sets collected
during the 1980-1992 drilling programme and survey of current aquifer conditions.
Detailed hydrogeological maps of various types and scales are available. They include :
· Hydrogeological reconnaissance maps (1:250,000) that summarise the
hydrogeological data for areas; the information includes yield potential, water
quality and where possible, flow directions (hydraulic gradient)
· Groundwater vulnerability and harvest potential maps in various scales
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· Extensive regional and local maps are present in various reports on projects
4.6.3
Groundwater Vulnerability to Pollution
The susceptibility or vulnerability of groundwater to anthropogenic pollution is defined as
"the tendency and likelihood for general contaminants to reach the water table after
introduction at the ground surface". The vulnerability of an aquifer to pollution depends on
the characteristics of the strata separating the saturated aquifer from the ground surface.
One the contaminants have arrived at the water table, the aquifer is deemed as polluted.
To assess the impact of contamination, groundwater vulnerability is related to the
groundwater resource.
The pollution of aquifers by human waste, urban run-off and other pollutants are described
by Coughanowr (1994). Coughanowr considers that in the developing world case studies
of severe groundwater pollution by hazardous and industrial wastes are rare. However, in
rural areas, there is increasing contamination of aquifers by fertilisers, pesticides and
human and animal waste. DRWS boreholes are only tested for bacterial contaminants if
health problems such as gastroenteritis, cholera or typhoid are reported.
Representative water samples are obtained after drilling or during testpumping procedures
for hydrochemical analysis of major ions and bacteria at WASA sites. Borehole sanitary
seals are grouted in around boreholes as part of standard operating procedures.
Protections zones are not demarcated around wellfields supplying the urban centres
therefore some of WASA's urban supply boreholes are already heavily polluted. There is
no routine in-country testing for heavy metals or organic contaminants that potentially pose
long-term pollution and health risks.
4.6.4
Drought Vulnerability Mapping
A drought vulnerability map aims to show regions where groundwater resources are
vulnerable to drought conditions to indicate the availability of the resource to provide a
supply during drought events. Key determinants of vulnerability include aquifer type, depth
of the weathered zone, well and borehole yields and rainfall (amount and variability). Such
a physical dataset identifying availability of resource and ease of access can be
superimposed on a sociological dataset, analysing the distribution of demand, to form a
composite drought vulnerability map. This map is then used to identify vulnerable
communities where efforts can be targeted to provide drought proofing in pre-drought
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periods, and to ensure that appropriate drilling methods and borehole designs are used
effectively.
Such a map of Lesotho would have been useful to The World Bank drought relief study of
1995. Lesotho would have been affected by the regional drought of 1984, 1992 and 1994
among others. Without long-term water level records to correlate with climatic records the
impact of drought events upon groundwater resources cannot be determined.
In areas underlain by low permeability aquifers where there are limited groundwater
resources, and borehole yields are low, the effect of prolonged periods of drought may be
disproportionately large especially if abstraction leads to the mining of the groundwater
resource.
4.7
Groundwater Resource Assessment and Exploration
The Groundwater Division of DWA is responsible for groundwater exploration and
resource assessment. Groundwater exploration procedures should generally be the
preserve of DWA and not consultants but due to lack of resources and expertise the
Division is limited in what it can achieve. DWA aims to assess the availability of
sustainable groundwater resources and borehole yields as well as economics of
groundwater development on a district / aquifer basis. Boreholes drilled for production
purposes can be regarded as exploration boreholes to maximise collection of data. Some
data sets are available in a number of reports on geophysical siting, drilling and
testpumping carried out during the Groundwater Project. These data sets and those from
subsequent exploration and development programmes need to be collected and collated
to present an overview of groundwater resources and development in Lesotho to
complement the hydrogeological map. Such a report would produce clear guidelines for
groundwater development and resource assessment / management.
TAMS (1996) estimated groundwater resources in terms of both dynamic (renewable) and
static resources for major surface water basins and administrative districts. Estimates of
groundwater usage were also produced using a rural water supply inventory and
administrative records. A potential and indeed very welcome outcome of this would be the
production of hydrogeological maps of Lesotho at a scale of 1:50,000 as tools for planning
and development.
The supervision of rural groundwater development by professional hydrogeologists or
suitably qualified technicians is rare due to the misconception that they are expensive to
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employ. In contrast, consultant hydrogeologists supervise the geophysical siting and other
aspects of urban water supply boreholes for WASA. The Groundwater Division lacks
experienced professional staff. The DRWS have no in-house hydrogeologists to supervise
and control borehole drilling and testing programmes they facilitate. This has led to poor
data collection and reporting. Few borehole records contain pertinent and relevant
information such as water strikes or lithological logs. Of the 5,000+ boreholes drilled by
DRWS to date, few comprehensive boreholes completion reports are available.
Hydrogeological supervision is provided on WASA drilling and testing programmes by
specialist consultants. The reporting standard is fairly high and analysis is provided.
Similar supervision and reporting were provided during recent groundwater exploration
programmes.
All borehole records for the Maseru region of DRWS pre 1988 were lost in 1998 when the
DRWS district office in Maseru was burnt to the ground. This clearly demonstrates the
requirement for a backup data system. The groundwater sector is poorly funded although it
plays an important role in the urban and rural water supply of Lesotho, as reflected in
public and private sector groundwater capacities. Neither DWA nor DRWS have sufficient
in-house groundwater expertise, therefore has to outsource these activities. The GWD of
DWA has some professional capacity with two drilling rigs and a testpumping unit.
4.7.1
Groundwater Reserves
The groundwater resources available for development can broadly be categorised as
dynamic reserves and static reserves. The dynamic groundwater reserve represents the
long-term average annual recharge under conditions of maximum groundwater use. Under
these conditions, the entire basin area forms the recharge area and groundwater
discharge occurs only through the pumping wells. Static reserve is the groundwater
contained within the permanently saturated zone of groundwater reservoir and represents
the total groundwater reserve minus the dynamic reserve.
Groundwater resources of Lesotho are summarised in Table 4-1. The resources are
calculated assuming specific yield values comparable with respective aquifers and the
water level fluctuation comparable with observed fluctuations in the monitored boreholes.
In order to calculate the static groundwater reserves, total reserves available from each
aquifer are worked out taking into account the thickness of the aquifer and its specific
yield. Subtracting the dynamic reserve from the total reserve gives the static reserve. This
groundwater reserve is available for future groundwater development in Lesotho specially
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to meet the water demand under emergency like severe drought. To make it more
comprehensive, the groundwater resources have been worked out on per square kilometre
basis. The complexity of hydrogeological conditions i.e. strong structural control of
groundwater by geological structures warrants that these resources should be explored for
occurrence and demarcation of exploitable aquifer zones.
Table 4-1: Groundwater Reserves of Lesotho
Water level
GW Resource
GW Resource
Aquifer
Area km2
Specific
Yield
fluctuation
MCM/year
per km2
Molteno
3777.99
0.015
2
113.33
0.03
Elliot
4331.30
0.01
1.5
64.96
0.015
Burgersdorp
3519.27
0.005
1
17.59
0.005
It is suggested that the vast available resources in Molteno aquifer and that it can
accommodate about 11 boreholes per square kilometre, each yielding 2 litres/sec on a 24
hour basis. It is considered that 2 litres/sec is the yield of a successful productive borehole
in Lesotho. Similarly Elliot aquifer can accommodate four boreholes per square kilometre
and Burgersdorp can accommodate two boreholes per square kilometre.
As far as the dynamic resource is concerned, there is still scope to sink more boreholes
within the safe yield limits of the annually renewable resource. However, in future, if there
is need to exceed the limits of dynamic reserve, no detrimental effect on the aquifer is
anticipated as it will provide scope for induced recharge from the runoff.
4.8
General Recommendations for Lesotho Groundwater Issues
Groundwater is used extensively within rural Lesotho, both as a source of domestic water
supply and for irrigation. Information derived from boreholes drilled by the Department of
Rural Water Supply should be used to provide indication of groundwater availability in
areas designated as potential sites for peri-urban and urban development by 2035.
Although these areas of the lowlands region of Lesotho are underlain by dolerite dyke
intruded Karoo age sedimentary rocks and basalts of low permeability and porosity, the
limited groundwater resources could provide temporary water supplies to newly formed
peri-urban areas.
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The vulnerability of these aquifers to pollution from effluent deposited in the large number
of pit latrines that proliferate within peri-urban settlements and associated waste disposal
sites needs to be assessed to define the limited period of useful exploitation. The results of
wellfield development undertaken for WASA by GWC and other consultants need to be
fully assessed and produced as a series of aquifer case studies to be used as conceptual
models for the development of further wellfields in areas of sufficient groundwater
development potential, as identified from the results of baseline surveys and GIS digitised
data.
It is essential that groundwater database and long-term monitoring systems be upgraded
to provide the necessary information if these developments are to take place. Groundwater
will continue to play a secondary but important role to surface water in supplying the needs
of Lesotho's peri-urban and urban populations.
4.9
Available Groundwater Reports
DWA
GWC
Ambrose
GWP
Ref
ref
ref
ref
Date
Title
Water Branch : Moroeroe Catchment
44
315
3
Oct 86
Area ­ Pumping Tests Prelim Report
14
319
4
Dec 86
Preliminary report on the boreholes
construction for the Butha Buthe
Hospital
15
321
5
Feb 87
Mafeteng LNDC Site: Groundwater
Forecasting
26
326
10
May 87
Project Lesili: Forecast of
groundwater resources
17
329
11
Jun 87
Final report on the boreholes
construction for the Butha-Buthe
Hospital
18
328
12
Jun 87
Teyateyaneng: Borehole field - St
Agnes Catchment Area
19
330
13
Jun 87
Butha-Buthe Woodlot nursery -
borehole pumping test
2
332
14
Aug 87
Village water supply: Thaba Bosiu
Pumping Test (Bh 8)
3
337
16
Sep 87
Village water supply: Masitise
Pumping Test (Bh10A)
46
17
Sep 87
Butha-Buthe: Base flow
measurements in 1983, 1984 and
1985
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DWA
GWC
Ambrose
GWP
Ref
ref
ref
ref
Date
Title
48
18
Oct 87
Hydrogeological outlines of
Maoamafubelu drainage basin
45
338
20
Nov 87
Village Water Supply
Hydrogeological survey at Ha
Ralejoe -Ha Phaloane
49
316
21
Nov 87
Khamane Village Pumping Test (Bh1,
Bh2)
50
336
22
Nov 87
Village Water Supply: Mese-Pela
pumping test (Bh1)
51
340
23
Jan 88
Leribe Woodlot pumping test (Bh1)
52
342
25
Feb 88
Lesotho Youth Service Train Work
Village Hydrogeological Survey
27
343
26
Feb 88
Geological Survey for Borehole
siting: Leribe District and Mafeteng
District
28
345
27
Feb 88
Forestry division: Maseru Woodlot
Nursery Hydrogeological survey for
borehole siting
29
348
28
Mar 88
Thabana Li Mele:'Craft centre':
Drilling and pumping tests on two
boreholes
30
349
29
Mar 88
Hydrogeological Investigation in
Mount Tabor
31
350
30
Mar 88
Sekameng Mine: Boreholes drilling
and pumping test
32
351
31
Mar 88
Masite Mission Pumping Test: Bh 11
33
353
33
Mar 88
Masianokeng Roads Camp
Hydrogeological Survey
34
355
34
Apr 88
Ha Ralejoe: Drilling and pumping test
on 3 boreholes
35
71
360
35
Jun 88
Water Branch: Boreholes survey for
Roma water supply
36
361
36
Jun 88
St Monica: Holy Family High School
water supply
37
365
41
Jul 88
Borehole Siting for Dilli Clinic,
Quthing
38
372
51
Oct 88
Letsie High School (Thaba-Bosiu)
39
373
52
Oct 88
VWS hydrogeological survey for
borehole siting Thiokol, Nqechane
Village, Leribe District
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DWA
GWC
Ambrose
GWP
Ref
ref
ref
ref
Date
Title
40
362
53
Oct 88
St Monica: Holy Family High School
Water Supply pumping test on bh No
2
41
377
54
Dec 88
Village Water Supply Geological
Survey for Bh siting, Ha Molokai:
Maseru District
42
375
55
Nov 88
Ts'a Kholo Area: Hydrogeological
Survey for bh siting
43
380
56
Jan 89
Linotsing Clinic Water Supply
44
383
57
Mar 89
Caledonspoort pumping test:
Archiplan studies
23
386
69
May 89
Linotsing pumping tests
76
393
71
Sep 89
Thabeng High School: pumping test -
Morija
11
400
76
Jan 90
Maputsoe Water Supply for Water
Branch
63
406
88
May 90
TY St Agnes water supply drilling and
pumping test
37
400
89
Jun 90
Teyateyaneng Water Supply;
Borehole Wellfield at Phuthiatsana
treatment plant
73
455
119
Oct 92
WASA borehole pumping tests
Katlehong and Lower Thetsane
47
335
Oct 87
Upper Koete Dairy Farm: Matsieng
(Bh 1)
47
279
Feb 83
Hydrogeological Survey in Morija
Wellfield
75
Feb 83
Hydrogeological Survey in Morija
Wellfield (possible duplication ­ see
above??)
30
290
Jun 84
National University of Lesotho Study
for Water Supply
310
310
Feb 85
Construction of 50 Boreholes in the
Rural Area of Tsa-Kholo - Mafeteng
District
9
314
Sep 86
Marsieng Water Supply - Preliminary
Report
8
364
Jul 88
Hydrogeological Investigation for
Butha-Buthe Water Supply: Drilling
and pumping test
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DWA
GWC
Ambrose
GWP
Ref
ref
ref
ref
Date
Title
24
452
Jul 92
Site visit to Maputsoe and TY
Wellfields
8
394
Sep 89
Progress Evaluation of the
Groundwater Project Activities and
Equipment Inventory
Mar 04
Six Towns Water Supply ­ Desk
Study and Siting Report.
Groundwater Consulting Services.
March 2004.
Key
DWA ­ Department of Water Affairs Library Number
GWC ­ Groundwater Consultants BeePee Library Number
Ambrose ­ Dr David Ambrose's Bibliography
GWP ­ Groundwater Project Technical Report Number
4.10 References and Additional Reports For Lesotho
Ambrose, D , 2001. Groundwater. Section 234, Lesotho Annotated Bibliography. Institute
of Education, National University of Lesotho. (See Appendix B)
ARDUINO, G, BONO, P AND DEL SETTE, P , 1994. Hydrogeological Map of Lesotho.
Scale 1:300 000. Lesotho Government, Ministry of Natural Resources, Department of
Water Affairs, Groundwater Division, in association with the Italian Government, General
Directorate of Development Co-operation, MOLISV ­ Groundwater Project.
BINNIE AND PARTNERS, 1971. Lesotho; study on water resources development;
inventory report. Vol. 2, Geology. UNDP/IBRD, London and Maseru (Chapter 4, 4.3
Boreholes, pp 35-42, Chapter 5 Groundwater, pp 35-50).
BINNIE SHAND LESOTHO, 1977. Twelve Towns Water Supply Study. Volume 6;
Supplementary Borehole Drilling and Testing Programme. Final Report, December 1977.
In association with Peat Marwick Mitchell for KfW, Lesotho.
BONNEY, G , 1975. Estimates of groundwater resources in Lesotho. Department of Mines
and Geology Geohydrology Section, Lesotho Government, Maseru.
BOTHA, J F , VERWEY, J P , VAN DER VOORT, I , VIVIER, J J P , BUYS, J ,
COLLISTON, W P AND LOOCK, J C , 1998. Karoo Aquifers: Their geology, geometry and
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Task 6: Groundwater
physical properties. Report to the Water Research Commission by the Institute for
Groundwater Studies, University of the Free State. WRC Report No. 487/1/98.
CHEVALLIER, L , GOEDHART, M AND WOODFORD, A C , 2001. The influence of
dolerite sill and ring complexes on the occurrence of groundwater in Karoo fractured
aquifers: a morpho-tectonic approach. Water Research Commission report No. 937/1/01,
146 pp
DAVIES, J , COBBING, J , ROBINS, N S , KULULANGA, G K , MANDOWA, W and
HANKIN, P , 2002. Development of a Curriculum and Training of Supervision Teams in
Borehole Construction in Malawi. British Geological Survey International Report,
CR/02/219N. pp. 27 and CD-ROM.
ENVIRONMENTAL BILL 2000; Government of Lesotho.
GKW CONSULT, 1998. Two Towns Water Supply Project: Butha Buthe Upgrading; Stage
2 Final Report December 1998. Water and Sewerage Authority, Lesotho. (WASA) .
GROUNDWATER CONSULTANTS, 1993. Groundwater development in Morija and
Teyateyaneng towns of Lesotho; Progress Report No. 1, February 1993. Water and
Sewerage Authority, Lesotho. (WASA) .
GROUNDWATER CONSULTANTS, 1995. Groundwater development in Maseru and peri-
urban areas of Maseru; Final Report, February 1995. Water and Sewerage Authority,
Ministry of Water, Energy and Mining, Lesotho. (WASA) .
GROUNDWATER CONSULTANTS, 1995. Groundwater exploration and development in
Leribe; Progress Report, May 1995. Water and Sewerage Authority, Lesotho. (WASA) .
GROUNDWATER CONSULTANTS BEE PEE (PTY) LTD, 2000. Six Towns Water Supply
Project. Project No. 7 ACP LSO 041. Preparation of Phase II, Final Report: Preliminary
Design Report. For: European Development Fund of the European Community and the
Water and Sewerage Authority (WASA), Ministry of Natural Resources, Lesotho.
GROUNDWATER CONSULTANTS, 2001. Development of a Code of Good Practice for
Groundwater Development in the SADC Region, Report No. 2 (Final). Guidelines for the
Groundwater Development in the SADC Region. For Southern African Development
Community (SADC), Water Sector Coordination Unit (WSCU)
JOHNSTONE, A , 1991. The results of the hydrogeological investigation of the South
Phuthiatsana river abstraction system supplying water to the Mashoehoe 1 International
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Airport. Groundwater Consulting Services for Department of Water Affairs, Ministry of
Water, Energy and Mining, Lesotho.
LAHMEYER INTERNATIONAL, 1992. Maseru Water Supply Phase III, Pre-feasibility
study, Volume 2, Main Report (Draft). October 1992. Water and Sewerage Authority,
Ministry of Water Energy and Mining, Lesotho. (3.7)
MACDONALD, A M, DAVIES, J, AND O'DOCHARTAIGH, B, 2001. Simple Methods for
assessing groundwater resources in low permeability areas of Africa. British Geological
Survey Commissioned Report, CR/01/168.
MEYER, R , 2002. Guidelines for the monitoring and management of groundwater
resources
in
rural water
supply
schemes. Water
Research Commission
report
No.861/1/02a, 59 pp
NATIONAL ENVIRONMENTAL SECRETARIAT (NES); 1998; Proposed Water Quality
Guidelines for Lesotho ­ Domestic (Drinking) Water Guidelines.
RIEMER, W , 1988. Two Towns Water Supply: Evaluation of options for groundwater
development. September 1988. Lesotho.
SAMI, K AND MURRAY, E C , 1998. Guidelines for the evaluation of water resources for
rural development with an emphasis on groundwater. Water Research Commission,
Pretoria. WRC Report No. 677/1/98.
SIR M MACDONALD AND PARTNERS IN ASSOCIATION WITH HIDROPROJECTO
CONSULTORES DE HIDRAULICA E SALUBRIDADE, 1990. Hydrogeological Map of
Lesotho. Scale 1:250 000. Cambridge and Lisbon. For the World Bank and United Nations
Development Programme.
TAMS, 1996a. Water Resources Management: Policy and Strategies, Final Report. TAMS
Consultants, Inc. New York with Sechaba Consultants, Maseru and BeePee Groundwater
Consultants, Maseru, for Department of Water Affairs, Ministry of Natural Resources,
Lesotho. (2.4.24), Section 1, Part 4 Groundwater Resources (pp 19-35).
TAMS, 1996b. Water Resources Management: Policy and Strategies, Annex D, Water
Resources Inventory, Volume 1 (Draft). TAMS Consultants, Inc. New York with Sechaba
Consultants, Maseru and BeePee Groundwater Consultants, Maseru, for Department of
Water Affairs, Ministry of Natural Resources, Lesotho. (2.4.10), Groundwater Resources
(pp 30-70).
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Task 6: Groundwater
UNDP, 1984. Geology and Mineral Resources of Lesotho. Exploration for Diamonds
(phase 1) and Exploration for Minerals (Phase 2). Technical report DP/UN/LES-71-503/8
and DP/UN/LES-73-021/9. For the Government of Lesotho. 252p.
VAN WYK, E , 2002. Establishment of departmental, national and regional groundwater
monitor committees. Department of Water Affairs and Forestry, Groundwater Resource
Monitoring and Assessment, 19pp
Water Resources Act 1978; Act no. 22 of 1978; Government of Lesotho.
WEMMIN, 1988. Maputsoe: Hydrogeological Survey for the town water supply.
Groundwater Project, Groundwater Division, Technical Report No. 38.
WOODFORD, A C AND CHEVALLIER, L , 2002. Regional characterisation and mapping
of Karoo fractured aquifer systems ­ an integrated approach using geographical
information system and digital image. Water Research Commission report No. 653/1/02,
192 pp
ZAPOROZEC,
A
,
(EDITOR),
2002.
Groundwater
Contamination
Inventory:
A
Methodological Guide. UNESCO, IHP-VI, Series on Groundwater No. 2.
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5
SOUTH AFRICA GROUNDWATER OVERVIEW
The Orange River rises in the eastern highlands of Lesotho where it is known as the
Senqu River and is the largest and longest river in South Africa and straddles five Water
Management Areas; Upper Vaal, Middle Vaal, Lower Vaal as well as the Upper and Lower
Orange Water Management Areas (WMA).
It is the main source of water for the Lower Orange WMA (including some users by
Namibia), and for the Fish to Tsitsikamma water management area. The Lesotho
Highlands Water Project, which is an integral and crucial component of the Vaal River
System, also relies on water, which under natural conditions would flow into the Upper
Orange WMA.
From the Upper Orange Water Management Area, the river flows through the Lower
Orange WMA where it discharges into the Atlantic Ocean some 2,300km from its origin in
Lesotho.
Substantial variation in climatic conditions occur over these catchments, with the Mean
Annual Precipitation (MAP) reducing from 1,500mm in Lesotho and 1,000mm in the RSA
in the Upper Orange to a mere 20mm along the western coast in the Lower Orange WMA.
This tendency is reversed when considering annual evaporation, which increases from
1,200mm in the Upper Orange to 3,000mm in the Lower Orange WMA. Agriculture,
mining, trade and Government are the main economic sectors contributing to the GDP in
the WMAs.
Extensive inter-catchment transfer schemes have been developed for the transfer of water
within the Water Management Area as well as to other WMAs. The most significant
transfers being from Katse Dam via the Lesotho Highlands Water Project to the Upper
Vaal WMA and from Gariep Dam via the Orange-Fish tunnel.
The main storage dams in the Orange River WMAs are :
· Gariep and Vanderkloof Dams on the Orange River, which command the two
largest reservoirs in South Africa. Hydropower for peaking purposes is generated
at both sites
· Armenia and Egmont Dams on tributaries in the Caledon sub-areas. Welbedacht
Dam is located on the main section of the Caledon River, with Knellpoort Dam an
off-channel storage dam that supplements Bloemfontein's water supply
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· Rustfontein, Mockes and Krugersdrift Dams are situated on the Modder river, and
the Tierpoort and Kalkfontein Dams on the Riet River
Katse and Mohale Dams in Lesotho do have significant impact on the available water in
the Orange River as the bulk of the Orange River flow is generated in Lesotho. Katse Dam
is located in the Senqu sub-areas of Lesotho and is used for the transfer of water to the
Upper Vaal WMA. Mohale Dam, which has recently been completed, is located in the
same sub-area. The dam is also used to support the transfer of water to the Upper Vaal
WMA.
5.1
Geology, Climate and Vegetation of the Orange River in South Africa
The river originates as the Senqu in the Maluti Mountains (rainfall >1,800mm per year) in
the highlands of Lesotho. The Lesotho Highlands consist mainly of basalt, and are covered
by alpine grassland with isolated high altitude marshy areas, giving rise to high quality
runoff. Some wooded areas occur in the valleys below the highlands. On the edges of the
overlying basalt, shales, sandstone and mudstone come to the surface, with resultant
highly erodible soils and high sediment loads in some areas.
To the west of Lesotho, the climate progressively becomes more arid. The vegetation
group consist of several Karoo and False Karoo veld types as well as significant Karoo like
invasions of other veld types. Rainfall here varies from 600mm per annum in the east to
less that 100mm per annum in the Richtersveld area. The geology is underlain by
sedimentary rocks (shales, mudstones and sandstones) of the Ecca and Beaufort Groups,
and the Karoo Supergroup, which have been intruded in places by dolerite sheets. The
Cape Supergroup is developed in the southern portion of the basin and consists of the
Table Mountain, Bokkeveld and Witteberg Groups. Sandstones and shales of the Table
Mountain Group are developed in the south and southwestern areas of the basin.
The Richtersveld area in the west of the basin is underlain by a variety of sedimentary,
metamorphic and volcanic rocks, with some unique and very striking features exposed by
the river. Precious little rainfall occurs from here to the Atlantic coast (0-100mm/a). The
area has a potential evaporation of over 3,000mm per annum, which is typical of a
temperate desert climate. Vegetation is sparse and is characterised by desert succulents,
including the famous Koker trees.
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5.2
Groundwater Development Potential and Related Issues
South Africa is divided up into 65 Groundwater Regions (see map overleaf) and
groundwater has always been an important source of rural water supply within the study
area. It provides water for domestic needs, small vegetable gardens and stock. The
generally low borehole yields and low storage of Karoo aquifers require large capital
expenditure to develop a large-scale supply. This in turn does not encourage farmers to
develop commercial scale irrigation. No quantitative estimation of a total rural water use
has been made. An exception to this is the high level of groundwater utilisation within the
Lower Vaal Water Management Area.
Numerous towns and villages in the basin have developed their own water supplies
utilising local groundwater. Larger towns, established at rivers, had sufficient financial
resources to build their own dams and water purification works. Groundwater is generally
used during droughts to supplement the shrinking dam reserves. With the increase of
urban population (the rural population has remained practically unchanged) during the last
few decades, DWAF developed an affordable subsidy system and grants for municipalities
and consequently more local dams were constructed. On a larger scale, the construction
of the Sterkfontein dam, together with water releases to the Vaal River drainage system
and water from the Katse dam in Lesotho, increased the availability of the surface water in
the central part of the basin. This resulted in a gradual decrease of groundwater utilisation.
Many towns switched to a conjunctive water use where municipal boreholes were used
only during peak seasonal demand and periodical droughts.
Recent municipal groundwater use has substantially decreased despite the overall
increase in the urban population due to surface water resources becoming available.
Unfortunately no accurate figures for current groundwater use are available. The generally
low degree of groundwater utilisation by the local authorities is the result of generally low
aquifer permeability and storativity, coupled with inherently low borehole yield.
Under these circumstances, any large groundwater development programme will be
expensive, and given the generally low development potential, not really recommended.
The subsequent high costs of a groundwater wellfield further question the viability of such
undertakings and ventures. Another important element to be factored in is the inherent
negative attitude and approach by potential groundwater users and this generally requires
interventions by institutional and social development facilitators. The lack of enthusiasm by
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beneficiary communities is in part based on the lack of confidence of the sustainability of
the resource as a result of no or little understanding of the groundwater regime.
Medium scale groundwater developments say for a single farm, industrial plant or small
community, if based on sound scientific approach can be economical. Engagement of
groundwater professionals in this process is now obligatory and hence will reduce the
usually large number of dry and unsuccessful boreholes drilled, eliminate improper
spacing of production boreholes and aquifer over-pumping, in addition to ensuring proper
and effective aquifer management procedures. This will improve overall wellfield
performance and resource sustainability. The proper application of the National Water Act
of 1998 can and will improve the confidence of the end-user in the developed resource
and encourage its sustainable utilisation.
The groundwater resources are somewhat limited in some areas and largely undefined
within the basin. The generally low yields of production boreholes are in the range of 1.5 to
2.0 litres/sec and groundwater extracted is at times saline (Vegter & Seymour, 1996). On a
local scale, groundwater is strategically important for some towns in the study areas as it
generally provides them with their primary water source. (Jolly, pers comm., 1995). From
available information, it appears no one full and detailed regional groundwater overview of
the complete basin area has been completed to date. The following section therefore
focuses on possible sources of groundwater within the general study area and their
relative association with geological units. DWAF has compiled a set of regional scale maps
outlining the groundwater potential of most of the Orange River Basin.
5.3
Groundwater Sources within the Orange River Basin
5.3.1
General
Aquifers can be divided into two broad classes and both occur within the study area.
Within Primary aquifers intergranular porosities and permeabilities occur which produce
the water-bearing characteristics. Some sandstones of the Beaufort Group are considered
to be weak primary aquifers (Loxton Venn, 1982). Secondary aquifers are aquifers where
the water-bearing characteristics are dependant on openings occurring within the rock
itself, which have occurred subsequent to deposition. Porosity is formed in weathered
rock, fractures or faults such as the in Karoo Supergroup. More specific aquifer types
occurring within the Orange River Basin are discussed in the following section.
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5.3.2
Dolerite Intrusions
Numerous dolerite dykes and sills have intruded the sediments of the Karoo Supergroup
throughout the basin. The dolerite themselves, or the baked contact zones between the
dolerite and the surrounding country rock are fractured and thus act as secondary
aquifers. Dolerite intrusions in competent host rocks such as the thick sandstones have
generally higher groundwater potential than intrusions in less competent rocks such as
shales. The highest groundwater yields would occur where a fractured dolerite / contact
zone is overlain by saturated alluvium or crossed by a perennial watercourse as this would
facilitate and promote aquifer recharge.
5.3.3
Fractured Sedimentary Rocks
Tectonic stress, for example, and the resultant folding and faulting have caused the
fracturing of sedimentary rocks and these fractures result in the formation of secondary
aquifers. The fracturing is most pronounced in competent (hard) sandstone units such as
those found in the Beaufort Group.
5.3.4
Weathered Zone
Weathered zones in which secondary porosity is created may also act as aquifers. Shales
and mudstones are more easily eroded than sandstone and this form of aquifer is
therefore often developed within the shales of the Ecca Group.
5.3.5
Alluvial Deposits
These have primary porosity and are developed to a limited extent along certain section of
the river
5.3.6
Upper Orange WMA Groundwater Overview
Underlain by hard formations, no large porous aquifers are found in the water
management area of the Upper Orange. Although relatively large quantities of
groundwater are abstractable from fracture zones at dolerite intrusions, recharge rates and
therefore the sustainable yields are low over most of the area. Higher recharge rates occur
in localised areas, such as where lime bogs are found. In the drier parts of the area,
groundwater constitutes the main, and in many cases the only source of water for rural
domestic supplies and stock watering, as well as for towns such as Colesberg. Severe
over-exploitation of groundwater occurs in some peri-urban areas, notably at the
Bainesvlei smallholdings near Bloemfontein. Groundwater over-exploitation also occurs at
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Petrusburg in the Riet / Modder sub-area due to increasing irrigation from groundwater.
The groundwater quality is naturally good in the eastern high rainfall parts of the basin,
becoming more mineralised and brackish in the drier areas and in the vicinity of saltpans.
A dolomite area (Karst Development) provides the source to numerous smaller rivers
including the Molopo, Marico and Harts Rivers and these aquifers extend north and
eastwards to the Crocodile (West) and Marico, Upper Vaal and Middle Vaal Water
Management Areas. The actual source of these rivers is referred to as "dolomite eyes" or
dissolution chambers, which are water bodies fed by groundwater originating from
fractures in the underlying dolomite. The water is typically alkaline having picked up
magnesium and calcium carbonates through solution from the parent dolomite. The Lower,
Middle and Upper Vaal Water Management Areas fall within the Orange River Basin.
5.3.7
Upper Vaal WMA Groundwater Overview
An important feature with regard to the groundwater resources of the Orange River Basin
is the large dolomitic aquifers of the Upper Vaal WMA. Much of the water in the Mooi
River, which is well known for its strong base flow, originates as springflow from these
aquifers. Large quantities of water are also abstracted through pumping for urban use
(such as Rand Water) and for irrigation. As a result of the direct hydraulic connectivity
between the dolomitic aquifers and surface streams, increases in groundwater abstraction
will result in corresponding decreases in surface flow. Dewatering of the dolomitic
compartment can also result in the formation of sinkholes. Extensive dewatering of the
dolomitic compartments for mining purposes has occurred in the northwest of Upper Vaal
WMA where gold deposits underlie dolomitic formations. This resulted in temporary
increases in surface flow while water tables were being lowered. Reductions in surface
flow will be experienced when mine pumping ceases and the compartments are allowed to
fill again. The remainder of the water management area is mainly underlain by fractured
rock aquifers, which appear to be well utilised for rural domestic supplies and stock
watering, with little undeveloped potential remaining. Although of specific importance in
some areas, only 3% of the total water requirements in the water management area are
supplied from groundwater.
Groundwater quality in the WMA is generally of an acceptably high standard. Due to
chemical reactions when groundwater infiltrates into mine caverns, poor water quality often
results which can cause serious groundwater pollutions.
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5.3.8
Middle Vaal WMA Groundwater Overview
Large dolomitic aquifers occur in the northern part of the water management area. These
extend from Stilfontein in a northerly direction across the WMA to the vicinity of
Ventersdorp. The aquifers, which occur in different compartments, also underlay large
sections of the WMA. Water from these aquifers is abstracted for urban domestic use at
Ventersdorp as well as being bottled. Water is also abstracted for irrigation and rural water
supply. The remainder of the water management area is mostly underlain by fractured rock
aquifers, which are well utilised for rural water supplies and with little undeveloped
potential remaining.
Dewatering of dolomitic compartments for mining purposes occurs in the vicinity of
Stilfontein, and pollution of groundwater due to chemical reaction may result when mining
operations are discontinued. Problems have been experienced with the seepage of
groundwater containing elevated manganese levels from mining areas into the Vaal River.
These problems have subsequently been addressed and remedial action taken. The
groundwater quality over the remainder of the water management area is generally of an
acceptably high standard. About 11MCM/a of water pumped from mine dewatering
operations evaporates from pans.
5.3.9
Lower Vaal WMA Groundwater Overview
The Lower Vaal groundwater utilisation is of major importance and constitutes the only
source of water over much of this WMA. Groundwater is mainly used for rural domestic
supplies, stock watering, potable water supplies to several towns in the area and in some
instances for irrigation, such as Tosca (see Chapter 5.3.10). Significant quantities of
groundwater are abstracted with the total yield from groundwater in the Lower Vaal WMA
more than double than that obtainable from the local surface water resources (WRP 2003).
Much of the groundwater abstraction in the Molopo sub-area is in the vicinity of dry sandy
riverbeds. With a substantial part of the recharge of groundwater assumed to be from
these watercourses, great concern exists about the impacts of upstream farm dams as
well as from invasive alien vegetation along the watercourses, on the sustainable yield
from groundwater.
Major de-watering of groundwater aquifers for mining purposes occurs at Sishen, where
up to 28MCM/a is planned to be abstract from groundwater. Expectations are that this will
stabilise at about 18MCM/a by the year 2027. The quality of groundwater in the Lower
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Vaal WMA is generally good, although brackish water does occur in some areas. Pollution
of dolomitic groundwater is occurs at the Pering Mine near Reivilo, as the direct result of
mining activities
5.3.10
Lower Orange River WMA Groundwater Overview
Groundwater is of major importance in the Lower Orange Basin and constitutes the only
source of water over large areas. It is mainly used for rural domestic supplies, stock
watering and water supplies to same inland towns. As a result of low rainfall over this
section, groundwater recharge is somewhat limited and generally only small quantities can
be abstracted on a sustainable basis. In the Orange River tributaries sub-area, about 60%
of the available water is supplied from various groundwater sources. Most, if not all, of the
groundwater abstracted near the river is directly from induced recharge from the river to
the local groundwater regime. Groundwater availability in the coastal region is extremely
limited as a direct result of the lack of rainfall and risk of seawater (saline) intrusion into the
coastal aquifers. Current utilisation of groundwater in the water management area is
thought to be approximately in balance with the sustainable yield from the source. No
significant potential for further development exists and some over-exploitation has been
experienced in certain areas within the coastal zone.
The groundwater quality varies from good to unacceptable in terms of potable standards.
The groundwater quality is one of the main factors affecting the development of available
groundwater resources. Although there are numerous problems associated with water
quality, some of which are easily corrected, Total Dissolved Solids (TDS), nitrates and
fluorides represent the majority of serious water quality problems that occur. Much of the
groundwater in the coastal zone is of poor quality (see map overleaf), containing elevated
levels of sodium chloride and is some cases traces of radioactivity.
For the optimum development of groundwater resources within the basin and elsewhere
for that matter, sound groundwater management practices are essential in order to prevent
over-exploitation and / or pollution of these valuable resources and in order to achieve
some measure of sustainable resource yield. The Karoo aquifers that cover virtually most
of the area have generally only a moderate development potential. Low permeability,
storativity and available aquifers storage are the limiting factors. Significant water
quantities can only be obtained by spreading a great number of boreholes over a large
area. This seriously influences the development costs and the final water cost.
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The most common groundwater management approach applied (where possible and
indeed feasible) should be the conjunctive use of groundwater and surface water.
Groundwater is accordingly used during dry periods when little surface water is generally
available (except for areas close to the river).
Proper management and monitoring of groundwater sources by municipalities and other
users are of vital importance. There is a need to provide groundwater information and to
create an improved understanding of groundwater at a local level (WRP, 2004).
Municipalities should investigate groundwater potential outside town boundaries as a
possible source. The reader is referred to Appendix A for more detailed information on the
groundwater issues of the WMA.
5.3.11
Groundwater Resources and Use : Mining and Industrial
Mining plays an important role in Lower Orange WMA's economic development. Several
diamond mines are located in the WMA including the Kleinzee, Alexcor and Hondeklipbaai
mines. Diamonds are recovered at these mines from alluvial deposits. A number of small-
scale diamond diggings are also found in the area. Some impacts do exist with regard to
localised dewatering of aquifers. These impacts appear to be localised and very little
information is available in the public domain. Black Mountain base metal mine utilised
surface water from the nearby Orange River for processes. No data is available on the
water resources utilised by the Okiep Copper Mines.
5.3.12
Groundwater Resources and Use : Agriculture
Most farming settlements are dependant on groundwater for domestic and stock watering
use. The groundwater resource is of such a nature that it cannot be utilised for large-scale
irrigation throughout the WMA, except in the areas underlain by dolomitic aquifers.
5.3.13
Groundwater Resources and Use : Domestic
As discussed above, groundwater is utilised for individual domestic use in most rural and
farming areas. Groundwater is the most important resource for bulk supply in areas
located far from the surface water bulk supply network. The naturally poor quality and poor
yields of some aquifers are a constraining factor in the utilisation of this resource. This is
overcome in some areas by good water management practices and treatment of the
groundwater.
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Data received from DWAF suggests the total abstraction of groundwater at some
10MCM/a for domestic supply for approximately 100,000 inhabitants dependant on the
source (DWAF,2003). The majority of the water (43%) is abstracted from granite and
gneiss aquifers, 25% is from the Dwyka and Ecca Karoo sediments, 17% from the
Beaufort Karoo sediments and the remainder from the dolomites (6%) and other primary
aquifers (2%).
5.3.14
Groundwater Abstraction: Additional Comments
Large abstractions (see Chapter 5.5) are generally the domain of the mining and irrigation
fraternity and the average water user is not in a position to exhaust the resource to the
extent that conflicting situations between different users are created. This is due to the
generally low aquifer permeability and small zone of influence of individual boreholes.
Some of the largest groundwater abstraction takes place in the Kroonstad / Welkom areas,
where mines of the Free State Goldfields are pumping approximately 33 X 106 cubic
metres annually of groundwater to the surface. Generally the elevated salinity level of this
water prohibits its utilisation and is thus mostly discharged to numerous evaporation pans
and dams. The effect of the dewatering on the shallow Karoo aquifer is considered to be
negligible as the mines are operating in a deep, confined aquifer. The pollution threat to
local, shallower groundwater by all surface mining related activities like tailing, dumps and
effluents etc. was acceptably addressed by the relevant mining companies.
Groundwater abstraction in excess of 1.2 X 106 cubic metres per annum occurs in the
Petrusburg surrounds and in an area northwest of Bloemfontein. Moderate groundwater
use for irrigation occurs in the Luckhoff, Hopetown and De Aar districts and in a few other
localities. Some towns and villages rely on groundwater and by way of example, the four
municipalities of De Aar, Jaggersfonten, Fauresmith and Reddersburg are currently using
groundwater in excess of 100,000 cubic metres per annum. Most farms are dependant on
groundwater for domestic use and stock watering but no total abstraction volumes are
available.
The following is a partial list of various municipal groundwater use to illustrate the
importance of groundwater use (E Baran 2001) and should not be viewed as a current
comprehensive account of municipal groundwater utilisation.
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Table 5-1: Municipal groundwater use
Town
Use
Report
Author
Date
Remarks
x103m/a
number
Vredefort
202
GH3340
J Coetzer
Oct 82
-
Leeudoringstad
249
GH1421
C Opperman
May 69
40% from private
boreholes
Newcastle
775
11/2/2/3
Town Eng.
1993
-
Newcastle Iscor
1,040
GH3282
J Kruger
Jul 83
-
Kroonstad
1,643
GH1798
W Boehmer
Jul 72
-
Cornelia
66
GH2995
O Gombar
Dec 77
83,000m3/a
could be safely
abstracted
Cornelia
26
GH3468
E Nealer
Jul 86
26,000m3/a
safely
abstracted??
Steynsrus
100-133
GH2961
O Gombar
Sep 77
76 private
boreholes
Petrus Steyn
135
GH2953
J Kruger
Aug 77
-
Clarens
60
GH3405
C Erasmus
Nov 85
Spring
augmented
Edenville
150
GH3902
T Kok
Jan 82
Pvt BHs
augment
Kastel
40
GH1796
W Boehmer
1972
-
Ficksburg
292
GH2818
P Smit and O
Feb 75
Infiltration gallery
Gombar
in Caledon River
supply 50% of
town's water
Soutpan
96
GH3496
G Bekker
Nov 86
-
Witsieshoek
1,700
GH2903
T Kok
Oct 76
-
5.4
Implementation of Groundwater Resource Directed Measures
The objective of resource directed measures (RDM) is to facilitate the proactive protection
of our water resources, in line with fundamental sustainability principles. The National
Water Act (NWA) recognises the need to develop and use our collective water resources
to grow. However, the Act also clearly recognises that our water resources are not be used
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to the detriment of future users. RDM hence strives to ensure that water resources are
afforded a level of protection that will assure a sustainable level of development for the
future. To this end, RDM comprises three main interrelated components, namely :
· Classification
· Reserve
· Resource Quality Objectives
It is important to remember that RDM is part of an overall iterative process to manage
water resources within South Africa, and should be implemented under ORASECOM,
within the basin member countries. RDM focuses on the basic principle of resource
sustainability, while equity and other related issues are effective addressed elsewhere in
the water management process.
5.4.1
Tosca Dolomite Aquifer Over Abstraction Case Study
The following is a summary from the WRC's Groundwater Resource Directed Measures
Manual (GRDM 2005) concerning lessons learnt from over abstraction and the subsequent
reduction in regional groundwater levels clearly demonstrates why ORASECOM should
implement resource directed measures.
The Tosca Dolomite Aquifer in the North West Province is recognised as a major aquifer
within the basin (as is the area northwest of Vryburg). As a result of the over-abstraction of
groundwater for irrigation from the Tosca Dolomite Aquifer, the aquifer is now regarded as
a stressed aquifer. Agriculture is the main activity in the area. Small-scale subsistence
farming predominated for a number of decades but a rapid escalation in the area of land
under irrigation has occurred in the last ten years. A concomitant increase in the volume of
groundwater abstracted and a resulting lowering of groundwater levels have accompanied
this.
Because of over abstraction of groundwater and subsequent associated conflicts, an
intermediate reserve determination was commissioned by DWAF and completed in April
2002.
Background Information
The study area is located in the North West Province and falls in the Lower Vaal Water
Management Area. Nearby settlements include Pomfret, Tosca and Morokweng with a
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combined total population of 14,500. Since 1990, rapid development of irrigation
transformed the socio-economic and environmental prospects of the area. By 2002, it was
estimated from registration of irrigation, satellite images, surveys and reports from farmers
that approximately 2,000ha were under irrigation. This amounts to some 18.9MCM/a being
abstracted for this purpose.
No surface water resources are used in the area due to the unreliability of the resource
and because of a lack of infrastructure. Groundwater is the sole source of water for both
agriculture and domestic requirements. The water use of stock, domestic and other
activities is considered negligible (0.5%) when compared to the volume used for irrigation
(99.5%). As such irrigation farming has placed an enormous strain on the dolomite aquifer.
A combination of factors led to the development of groundwater for irrigation purposes.
During 1990, the CSIR undertook a geohydrological investigation of the area and
characterised the groundwater resources as high yielding. Quality and isotope samples
were taken from the water at that time indicated that some of the groundwater was fossil
water (long residence times). This suggested that the sustainability of the resource was
not as high as the borehole yields indicated. Nonetheless, the farming community pressed
on with the development of groundwater and established irrigation-based crops.
Physiography and Climate
The area of interest is characterised by a flat topography. From the watershed in the east
at 1210m the elevation gradually declines to 1070m in the west over a distance of 60km.
The only topographic features being the Waterberge rising to 50m above the plain to the
north and a number of non-perennial riverbeds. The area experiences a mean annual
rainfall (MAR) of about 400mm/a with a potential evaporation loss of more than 2000mm/a.
Most rainfall occurs during the summer months.
Sediments of the Kalahari Group underlain by Karoo cover much of the area. The sub-
outcrop geology is shown in Figure 5-1 and a SW-NE cross section of the study area is
presented in Figure 5-2. The study area occupies some of the quaternary catchments
within the Lower Vaal Water Management Area but the main focus was over the stressed
Tosca ­ Vergelegen Aquifer.
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Figure 5-1: Pomfret ­ Vergelegen Dolomitic Aquifer showing sub-outcrop Geology
Figure 5-2: Cross-section through the Tosca Dolomitic Aquifer
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The area is drained by the Thlagameng, Vals, Doring and Wildebeesthoring Rivers, which
all drain into the Molopo River. The rivers are ephemeral and no flow occurs for between
60 and 70% of the year. The Molopo River is an influent river that recharges underlying
aquifers during runoff events.
Geohydrology
Dolomitic aquifers are the major aquifer types in the study area. Localised areas of
significant groundwater potential are associated with fault zones where fracturing,
weathering and leaching of the rock has occurred. The fault zones vary from a few metres
to tens of metres in width and can extend laterally for several kilometres. Brecciated fault
zones consist of fractured dolomite, small solution cavities and Mg-rich wad material.
Borehole yields range between 0.1 litres per sec and 126 litres per sec with average yields
around 6.3 litres per sec.
In the northern parts of the study area, the dolomite is underlain by banded ironstone
formations. Due to the low dip angle of these formations, the majority of the boreholes
drilled into the banded ironstone penetrate the underlying dolomite formations. Natural
groundwater levels vary between 5 and 10m below ground level (mbgl) in the west and to
between 50 and 60mbgl northeast at the Molopo River.
Regional groundwater levels measured during a hydrocensus of the area in 1977 and
again in 1990 (Duvenhage & Meyer, 1991) were available to assess reference conditions
(see Figure 5-3).
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Figure 5-3: Groundwater level contours (mamsl) for 1977 (left) and 1990 (right)
Only minor changes in groundwater levels were evident between 1977 and 1990. The
most significant differences in groundwater levels were elevated groundwater levels along
the Molopo River and elevated groundwater levels along the dyke swarms parallel to the
Quarreefontein dyke. Nonetheless, the groundwater levels in 1990 are still considered
unimpacted and representative of reference conditions.
According to Vegter (WRC, 1995), recharge within the catchment ranges between 3 and
12mm/a. Recharge software developed by van Tonder (2000) was used to assess
recharge. Areas of highest recharge are shown in Figure 5-4.
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Figure 5-4: Areas of highest recharge
Recharge to the Tosca Dolomitic Aquifer was calculated to be 6.9MCM/a. Based on
results from applying the Chloride Recharge Method, the following mechanisms of
recharge to the dolomitic aquifer were considered important :
· Recharge through geological lineaments (faults, not dykes)
· Recharge through shallow outcrop and sub-outcrop of dolomite (southwestern
area)
· Recharge through banded ironstone formation (northern border areas)
· Recharge through alluvial channels
Groundwater usage in the area has periodically been assessed by DWAF between 1990
and 2002. Abstraction from the Tosca Dolomite Aquifer increased dramatically from
2MCM/a to over 12MCM/a during this period. This abstraction has lead to an alarming
decline in groundwater levels in the area (see Figure 5-5 and Figure 5-6). Between 1990
and January 2002, groundwater levels declined by as much as 60m in the southwestern
part of the Tosca Dolomitic Aquifer and the southeastern part of the Pomfret Dolomitic
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Aquifer. These areas coincide with areas of intense pivot irrigation, as indicated by the
blue circles in Figure 5-6.
Figure 5-5: Groundwater level contours mamsl 1990 (left) and 2002 (right)
Figure 5-6: Difference in groundwater levels between 1990 and 2002. Blue circles
represent areas of intense pivot irrigation
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Recharge to the Tosca Dolomitic Aquifer was estimated to be 6.90MCM/a with an
associated abstraction of 12.1MCM/a has clearly indicated an over-pumping of the aquifer
of some 5.3MCM/a. Hence the subsequent classification of the aquifer as critically
stressed.
It is evident from the assessment of groundwater levels and usage that at some point
between 1990 and 2002, the sustainable yield of the aquifer was exceeded, causing a
rapid decline in groundwater levels and as a result of this resource mismanagement, the
aquifer is considered stressed.
Resource Quality Objectives (RQO) ­ Remedial Action
As a result from the GRDM assessment, the following Resource Quality Objectives to
address the current unsustainable groundwater abstraction from the aquifer were
proposed :
Groundwater levels in the Pomfret ­ Vergelegen Dolomitic Aquifer should not be allowed
to decline any further over the long-term
This objective can only be achieved by reducing abstraction from the aquifer and allowing
groundwater levels to recover. No new production boreholes should be drilled in recharge
areas or in currently over-utilised dolomitic compartments. Existing production boreholes
should not be pumped at more than 60% of their tested sustainable yield, and should not
be pumped continuously for more than 12 hours per day. Spacing between production
boreholes should be optimised to reduce further interference.
Summary and Conclusions
While groundwater plays no part in sustaining river flow in the area and the volume of
groundwater required to meet basic human needs too small, over abstraction of
groundwater for irrigation purposes has resulted in a critical decline in groundwater levels
in the Tosca Dolomitic Aquifer. The aquifer is classified as critically stressed and over-
exploited. Groundwater levels should not be allowed to decline any further and
management actions are required to allow the aquifer to recover. A groundwater allocation
plan has been developed in consultation with groundwater users to reduce groundwater
abstraction by about 50% over a five-year period.
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Thus the effective implementation of the GRDM programme within the Orange River Basin
will determine the classification of significant water resources, set the Reserve and help
define resource quality objectives.
5.5
Geohydrological Data and Mapping (National and within the Basin)
A programme of geohydrological mapping was embarked on in 1993 as a means of
providing a quick overview of groundwater information (Vegter 1994). The Water Research
Commission (WRC) and DWAF published a set of national maps (which included most of
the basin on the SA side) together with an explanatory document in 1995 depicting in two
A2 sized sheets (Vegter 1995) :
· Borehole prospects
· Saturated interstices
· Mean annual recharge
· Groundwater component of river flow
· Depth to groundwater level
· Groundwater quality
· Hydrochemical types
5.5.1
1:500 000 Map series
DWAF has embarked on the production of a general geohydrological series on a scale of
1:500 000 and the programme is currently on going.
5.5.2
Vulnerability Map
Understanding and recording the susceptibility of groundwater to pollution is important.
Lynch et al. (1997) applied the DRASTIC concept (Aller et al. 1987) and GIS technology to
produce a groundwater vulnerability map of South Africa. The map should be seen as a
first attempt at depicting vulnerability using methodology initially developed for U.S.A.
conditions. It has some limitations inherent to DRASTIC methodology and shortcomings in
that certain data sets were not available and assumptions had to be made (Vegter 2001).
5.5.3
Groundwater Harvest Map
The Groundwater Harvest Potential Map of South Africa 1996 (Baran et al. 1998) is a
derivative of the set of maps "Groundwater Resources of South Africa" published in 1995.
Paraphrasing
from
the
accompanying
explanatory
report:
"The
map
quantifies
groundwater resources. It permits direct comparison of different groundwater areas and
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facilitates comparison with surface resources. Harvest potential is the sustainable volume
of groundwater that may be abstracted per Km2 per annum."
5.5.4
Groundwater Recharge Maps
Two national scale maps of recharge are currently available. While preparing his
geohydrological maps of South Africa, Vegter (1995) attempted to quantify recharge (see
map overleaf). Schulze (1997) prepared a similar map, but of the annual recharge of soil
water into the vadose zone (unsaturated). Both maps are deemed useful of obtaining a
quick indication of recharge in a particular area. However, they must be used with caution.
They provide only an indication of average recharge over an area, and cannot be used to
determine recharge on a local scale. Whenever possible, more detailed and site-specific
information should be used.
5.5.5
Available Groundwater Data
The following data sources with regard to groundwater related issues are available:
· NGDB database
· WARMS database
· Catchment Management Studies / Reports
· DWAF GH (Geohydrology) Reports
· WRC projects and related reports
· Geohydrological maps
· Consultant reports
Although there are may available sources of groundwater data it is often not easy, and at
times frustrating, to access the data. The NGDB and WARMS databases are populated
with a number of points. However, the NGDB often only contains water level
measurements. Very little is available on abstraction volumes and groundwater quality.
The WARMS database contains information regarding abstraction of groundwater for all
registered and licensed users but this data still needs to be verified.
Other data sources in the public domain include Catchment Management Studies,
geohydrological maps (e.g. Vegter and Barnard) and GH and WRC reports and studies.
Some Environmental Impact Reports (EIRs) dealing with impacts on the groundwater
domain are also available. This data is valuable since the studies are mainly focussed on a
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regional scale and deals with specific groundwater related problems. It should be noted
that this data should be centralised in a database such as WMS or NGA / NGDB in order
to make the data more accessible for management purposes.
Another source of valuable information that is not readily available is consultant reports.
Often industries and mines request consultants to investigate specific groundwater issues.
The reports are generally discussed with DWAF but the data does not land up in the public
domain. In spite of repeated requests for report listings, most consultants failed to
respond. The reluctance to divulge information (especially information paid for by State
funds) is unfortunately an inherent problem and systems should be put in place to ensure
compliancy.
The reader is referred to Appendix B for references and detailed information on the
availability of groundwater related data, its status, and format and confidence levels
expressed in the data sets. The information is also available on the attached CD in an
ACCESS database file and some notes are attached in Appendix B describing the
operation of the database.
5.6
Additional Relevant Groundwater Comments and Observations
Besides the various major mining activities, major industries in the basin include Sasol
Chemical Industries, DOW Chemicals, and Omnia fertiliser, Iscor, Sappi, AECI, Sasol
Synthetic Fuels and Samancor Base Metal Refinery. None of these industries utilise
groundwater as a resource but they do have localised impacts on the groundwater quality.
The Upper Vaal WMA falls within the most highly industrialised zone in the country and the
industries are very diversified. Little site-specific data is available in the public domain
regarding industrial pollution but from the nature of the activities, the principle potential
problems can be highlighted. The major impacts from power stations, in terms of
groundwater quality, are associated with the ash disposal and coal stockpiling areas.
Hodgson and Krantz (1998) have indicated the major groundwater quality concerns at
power stations are elevated sulphates, elevated TDS values and in certain cases very high
pH waters. Where these high pH conditions exist, metals such as Al and Mn can go into
solution and are cause for great concern.
Gold mining with the WMA on the West and East Rand and coal in the Vaal basin has
contributed to the regional degradation of groundwater quality and a broad encompassing
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study should be implemented to delineate the degree of point and diffuse groundwater
pollution.
Management of the groundwater resource in this strategically important WMA takes place
on an adhoc basis (Fayaz, 2003) due to the lack of capacity in the Geohydrology Division
of DWAF's Gauteng Regional Office. Only groundwater problems that require immediate
attention are addressed. This management style impacts negatively on the valuable water
resources. Provision should be made for adequate professional staffing levels to
effectively manage the resource.
5.7
Groundwater Monitoring
Groundwater in South Africa was regarded as private under the 1956 Water Act, and as a
result its status was not monitored or assessed to the same extent as surface water.
However, groundwater has the potential to contribute significantly to meeting the needs for
water in rural areas, particularly for domestic supply. Existing monitoring networks will
need to be expanded and refined, and surveys undertaken to improve understanding of
the quantities and quality of water available if this potential is to be realised and the use of
groundwater integrated with surface water use (conjunctive use).
Groundwater levels and water quality are currently recorded on a continuous basis at
some 150 points and at regular intervals at about another 1,000 points. Continuous
monitoring at an estimated 460 points is required for an effective national network. The
current understanding is for DWAF to refine and develop the present system (which will
have direct benefit for the ORASECOM programme) to create an integrated monitoring
network at three levels, namely
· National monitoring by the Department in relatively unimpacted areas to provide
background and baseline information on water levels and water quality. The
establishment of this part of the network has the highest priority and its expansion
is planned for completion by 2006
· Monitoring of major aquifers by catchment management agencies to determine
trends in water levels and water quality resulting from human activity. This will
initially only cover physico-chemical monitoring, although scope will eventually
need to be expanded to microbial, toxicity and radioactivity monitoring. The
Department will continue with this monitoring until the catchment management
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agencies can take over the responsibility. Pilot networks have been established in
the water management areas that have been prioritised
· Local impact monitoring. Information provided by users in terms of the conditions
attached to general authorisations and licensing will have an important source of
information on groundwater use. Additional information will be derived from
reports on conditions encountered during borehole drilling
5.8
South African References
Department of Water Affairs and Forestry, South Africa. Upper Orange Water
Management Area : Overview of Water Resources Availability and Utilisation. Report
Number P WMA13/000/00/0203. Complied by BKS (Pty) Ltd as part of the development of
the National Water Resources Strategy, 2003
Department of Water Affairs and Forestry, South Africa. Lower Orange Water
Management Area : Overview of Water Resources and Availability. Report Number P
WMA14/000/00/0203. Compiled by BKS (Pty) Ltd as part of the development of the
National Water Resources Strategy, 2003.
Department of Water Affairs and Forestry, South Africa, 2004. National Water Resource
Strategy : First Edition.
Department of Water Affairs and Forestry, South Africa. Internal Strategic Perspective for
the Upper Orange Water Management Area. Report Number P WMA13/000/00/0304.
Compiled by PDNA, WRP & WMB as part of the development of the National Water
Resources Strategy, 2003.
Department of Water Affairs and Forestry, South Africa. Internal Strategic Perspective for
the Lower Orange Water Management Area. Report Number P WMA14/000/00/0304.
Compiled by PDNA, WRP & WMB as part of the development of the National Water
Resources Strategy, 2003.
Department of Water Affairs and Forestry, South Africa. Internal Strategic Perspective for
the Vaal River System Overarching. Report Number P WMAC000/00/0103. Compiled by
PDNA, WRP & WMB as part of the development of the National Water Resources
Strategy, 2003.
BKS (Pty) Ltd., May 1997. Overview of Water Resources Availability and Utilisation in
South Africa.
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Vegter, J.R. 1990. An explanation of a Set of National Groundwater Maps. WRC Report
Number TT 74/95.
Vegter, J.R. 2001. Groundwater Development in South Africa and an Introduction to
Hydrogeology of Groundwater Regions. WRC Report Number TT 134/90.
Baran, E. 2003. An Explanation of the 1:500,000 General Hydrogeological Map. Kroonstad
2725.
Meyer, P.S. 2003. An Explanation of the 1:500,000 General Hydrogeological Map.
Bloemfontein 2924.
Duvenhage, A and Meyer, R., 1991. Geohydrological and Geophysical Investigation in the
Tosca-Vergelegen areas. CSIR Report EMI-C 91179.
Department of Water Affairs and Forestry, 1996. Groundwater Harvest Potential of the
Republic of South Africa. Map Sheet.
Department of Water Affairs and Forestry, 1999. Resource Directed Measures for
Protection of Water Resources; Groundwater Component, Version 1.0, DWAF Pretoria.
Godfrey, L and van Dyk, G., 2002. Reserve Determination for the Pomfret ­ Vergelegen
Dolomitic Aquifer, North West Province. CSIR Report Number ENV-P-C 2002-031.
Parsons, R and Conrad, J., 1998. Explanatory Notes for the Aquifer Classification Map of
South Africa. WRC Report Number KV 116/98.
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6
GROUNDWATER INFORMATION SYSTEMS FOR ORASECOM IWRMP
It is clear that groundwater information for the Orange River Basin is currently held by
varies institutions in many various forms and formats, and such dissemination of
information is a waste of a valued resource. Availability of timely, adequate and valid
geohydrological data and information will be crucial to the success of the ORASECOM
IWRMP. It is imperative, therefore, that collection of new geohydrological data be
accompanied by the continuous enhancement of powerful and standardised (within the
SADC Region) information tools such as databases, information systems, maps and
reports. These should be used to convey the relevant information to ORASECOM,
Government departments within the basin member countries, geohydrological specialists,
water resource managers, decision makers and other interested parties.
Information can be made available in various formats. The classic formats such as printed
maps and reports are important, but increasingly these are supplemented by electronic
(digital) systems, which are capable of supplying data customised for specific purposes.
The printed maps are key and important tools in water management and the ORASECOM
Commissioners should hold a relevant selection.
A number of computer-based systems are available for storing and sharing of the
geohydrological data and information, in addition to libraries and technical reports in the
four basin member countries. In South Africa, a new portfolio titled the National
Groundwater Information Systems (NGIS) is in the final stages of design to meet
increasing demands for groundwater information in a rapidly changing water business
sector. The NGIS portfolio includes several projects. Amongst the most important are
REGIS Africa and National Groundwater Archive (NGA). The latter is a relational database
management system. The system will be distributed among regional offices, and will
integrate both spatial and non-spatial data and information. It also accommodates
increased visualisation and analytical functionality.
The mainframe-based National Groundwater Database (NGDB) has been replaced with a
server-based system as a bridging solution until the web-based National Groundwater
Archive (NGA) becomes operational. The development of the system and the transfer of
data is expected to be completed soon. The Institute for Groundwater Studies (IGS)
maintain the HYDROCOM database but proprietary software is required to access the
data sets. The National Water Quality Database (NWQDB) containing over 55,000
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analyses of groundwater samples, mostly of macro elements, has recently been replaced
with the Water Management System (WMS). Data from the National Groundwater Quality
Monitoring Network has been included. To make the database useful over a long period of
time, it is important that the collected data sets are comparable. The features of the some
of the geohydrological / hydrological information systems with DWAF SA relevant to
ORASECOM IWRMP are listed in the table below :
Table 6-1: Features of some grohydrological / hydrological information systems
REGIS
HydSys
WMS
WSAM
WARMS
Primary Function
Geohydrology
Surface
Water
Water
Authorised
hydrology
quality
situation
water use
assessment
Mapping
ArcView
Proprietary
ArcView
ArcView
None
Component
formats
present
Database
Oracle
Proprietary
Informix
Access
Informix
Data exchange
ASCII tables
ASCII
ASCII
ASCII
ASCII
Spatial Data
Shape files
Shape files
Shape
Shape files
Shape files
Exchange
files
A problem of many databases and information systems is incorrect data. This is damaging
to the trust and hence usefulness of the database and systems and structures should be in
place to ensure the risks are minimised.
Given the dispersed nature of the huge volume of information and the fact that most of the
data is in a non-digital format, information verification is not feasible under the current
available project funding. The annual allocation of only 100,000 Euros is drawing out and
delaying the tasks and ways must be found to either bridge finance the project or to
convince the funding agent to provide the full budget in one year.
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7
CONCLUSIONS AND RECOMMENDATIONS
If groundwater is to be included in not only the ORASECOM IWRMP but also any other
Integrated Water Resource Management Plan, management of groundwater has to
comply with the policy, strategy and practice of common standardised water resource
management within the Orange River Basin and all of its member states. Where
management practises must differ from, or be modified to accommodate unique
geohydrological characteristics, a clear statement from the Geohydrological Department of
the relevant ORASECOM basin member country should be required as to why the policy,
strategy applied in the IWRMP cannot be applied to the management of groundwater.
The following conclusions recommendations are aimed at setting up mechanisms to fill the
data gaps and identify additional systems and structures needed:
· Management of the water resources in the Upper and Lower Orange WMAs, as
well as the Upper, Middle and Lower Vaal WMAs must be within the framework of
ORASECOM as should the relevant areas in the bordering countries
· The already full development utilisation of groundwater and surface water
resources across most of the remaining WMAs with the Orange River Basin (on
the SA side especially) should become key ORASECOM management
considerations
· Explore and promote the conjunctive use of groundwater (augment surface water
where feasible)
· Botswana's groundwater potential within the Olifants Sequence north of
Middelpits needs to be quantified as reports suggest the area had good
groundwater development potential
· Any groundwater development concerning spatial flow in transboundary/shared
aquifers needs to be managed in a sustainable and responsible manner
· The Kalahari Sequence basal aquifer potentially constitutes a useful resource and
additional studies are needed to further delineate the zone
· Planned development resulting in over-exploitation and stressing of the Kanye
wellfield in Botswana needs careful planning and investigation before project
implementation
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· Orange River Basin groundwater development and associated recharge potential
needs to be better understood and additional studies are needed before accurate
localised maps can be produced
· All mining institutions should be encouraged to place all groundwater related
information in the public domain
· The four basin member countries should all work towards using common borehole
design, construction methods and data management procedures
· More comprehensive bibliographical data needs to be supplied by consultants.
Consultants inherently are reluctant to part with report listing information and it is
suggested that relevant systems and structures are put in place to address this
· Improved management style by the provision of adequate professional staffing
levels to more effectively manage and monitor groundwater resources
· Collect, geo-reference, collate and digitise all available data from all available raw
data files. Store data in common readily accessible and updateable databases
· Maintain existing and establish new effective groundwater monitoring systems
and undertake hydrochemical and hydrocensus baseline surveys
· Produce geological and hydrogeological maps from digitised regional data
· Produce soil distribution maps from digitised regional data
· Produce fracture analysis map (satellite imagery) from digitised regional data
· Produce dyke distribution map (use areomagnetics) from digitised regional data
· Produce digital terrain map
· Produce groundwater use map (from hydrocensus and other relevant data)
· Digital data for the above entered into a GIS would enable various data layers to
be combined to produce a map of groundwater resource development potential
for designated peri-urban and urban areas
· Exploration (investigation) boreholes should be drilled within those areas
identified for peri-urban development to determine their groundwater development
potential for interim (conjunctive use/augmented) water supply
· Aquifer vulnerability mapping in selected and relevant (urban / peri-urban and
adjacent rural areas) to identify susceptible zones
· Hydrocensus survey to assess the distribution of dry, failing and successful
boreholes that could be used to indicate areas of good groundwater development
potential. This survey would indicate which of the designated urban areas could
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be supplied from groundwater sources. The survey should include all aspects
such as GPS location, yields, water quality etc.
· Study of the pollution threats from mining, agriculture and from pit latrines (VIPs)
especially in areas identified for peri-urban development
· Groundwater use / utilisation survey with the four basin member countries to
determine the overall distribution of groundwater abstraction, which will help
identify areas where groundwater can successfully be used for rural and peri-
urban development etc.
· Implementation and use of Groundwater Resource Directed Measures based on
the WRC SA Model and guidelines by the domestic groundwater institutions
should be encouraged in all basin member countries
· Survey of groundwater wellfields to assess their long-term sustainability and
reassess their groundwater resources (development potential). Information
derived from the development of these wellfields could be compiled as a series of
case studies to be used in the planning and design of wellfields in similar
hydrogeological environments
· Improved collection of all geological information (such as lithological logs) etc.
· Detailed hydraulic parameters such as permeabilities and porosities from core
plug samples and data derived from other relevant testing procedures
· Logging of boreholes will inform patterns of groundwater flow and other aquifer
hydraulic characteristics
· Available hydrochemical data to be processed, statistically analysed and
published in the form of maps
· Reconnaissance or broad encompassing surveys to locate significant dispersed
and point pollution or contamination of groundwater and other risks
· Investigation of groundwater-environmental interactions (especially in the
developed and industrialised zones of the basin)
· More attention should be given to groundwater balance determinations for
estimating recharge in the basin
· Groundwater modelling should be developed increasingly into a more useful and
strategic tool
· Data acquisition storage and processing facilities needs to be greatly improved
and expanded
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· Groundwater data and information of certain geohydrological units (important
aquifer areas) within the basin should be processed and compiled in the form of
basin specific geohydrological maps and groundwater assessment inventories
· Verification of data contained in the WARMS database
Many issues have been raised relating to practical problems experienced in managing
Southern Africa's groundwater resources. Many of the problems relate largely to the
separate manner in which groundwater is managed. In essence, five generic strategies
are proposed to change the traditional approach and ensure successful implementation:
· Integrate groundwater into the management of water resources for the benefit of
all
· Actively promote groundwater and the conjunctive use of groundwater so that
water resource managers, water-users and the general public are more aware of
the role, occurrence and value of groundwater
· Encourage and enable Geohydrologists to work outside their line function, and be
integrated into the broader water resource planning and management functions
· Develop a larger, skilled and experienced specialist geohydrological workforce
· Develop a common groundwater monitoring network and a common
geohydrological information system to assist in the provision of data to those who
need it
The simple fact that groundwater is used as a source of water for more than 15 million
people in South Africa alone, clearly demonstrates the importance of the resource. It is no
longer acceptable to manage groundwater in a separate manner and by the conjunctive
use of the resource, the effective use of groundwater will gain wider acceptance.
From available information, it appears no one full and detailed regional groundwater
overview of the complete basin area has been completed to date and it is therefore
recommended that a full and detailed regional study encompassing the co-basin member
states be conducted. A strategy to accomplish these needs to be developed.
On an international and national level, co-operative governance needs to be factored into
the overall integrated water resources management undertakings, to ensure a benefit to all
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users. Existing local and international communication systems should be fully utilised to
keep track of proposed water resource developments and planning.
Bold initiatives are required to ensure the ORASECOM Integrate