E-Flows Ecological and Social Predictions Scenario Report
Okavango River Basin
Environmental Flow Assessment
Scenario Report:
Ecological and Social Predictions
(Volume 1 of 4)
Report No: 07/2009
J.M. King, et al.
December 2009
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E-Flows Ecological and Social Predictions Scenario Report
DOCUMENT DETAILS
PROJECT
Environment protection and sustainable management of
the Okavango River Basin: Preliminary Environmental
Flows Assessment
TITLE:
Scenario Report: Ecological and social predictions
VOLUME:
Volume 1 of 4
DATE: December
2009
LEAD AUTHORS:
J.M. King, C. A. Brown.
REPORT NO.:
07/2009
PROJECT NO:
UNTS/RAF/010/GEF
FORMAT:
MSWord and PDF.
CONTRIBUTING AUTHORS:
A.R. Joubert, J. Barnes, H. Beuster, P. Wolski.
THE TEAM
Project Managers
Colin Christian
Dominic Mazvimavi
Chaminda Rajapakse
Barbara Curtis
Joseph Mbaiwa
Nkobi Moleele
Celeste Espach
Gagoitseope Mmopelwa
Geofrey Khwarae
Aune-Lea Hatutale
Belda Mosepele
Mathews Katjimune
Keta Mosepele
Angola
assisted by Penehafo
Piotr Wolski
Manual Quintino (Team
Shidute
Leader and OBSC
Andre Mostert
EFA Process
member)
Shishani Nakanwe
Management
Carlos Andrade
Cynthia Ortmann
Jackie King
Helder André de Andrade
Mark Paxton
Cate Brown
e Sousa
Kevin Roberts
Hans Beuster
Amândio Gomes
Ben van de Waal
Jon Barnes
Filomena Livramento
Dorothy Wamunyima
Alison Joubert
Paulo Emilio Mendes
assisted by
Mark Rountree
Gabriel Luis Miguel
Ndinomwaameni Nashipili
Miguel Morais
Okavango Basin
Mario João Pereira
Botswana
Steering Committee
Rute Saraiva
Casper Bonyongo (Team
Tracy Molefi-Mbui
Carmen Santos
Leader)
Laura Namene
Pete Hancock
Namibia
Lapologang Magole
Shirley Bethune (Team
Wellington Masamba
Leader)
Hilary Masundire
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E-Flows Ecological and Social Predictions Scenario Report
List of reports in report series
Report 01/2009:
Project Initiation Report
Report 02/2009:
Process Report
Report 03/2009:
Guidelines for data collection, analysis and scenario creation
Report 04/2009:
Delineation Report
Report 05/2009:
Hydrology Report: Data and models
Report 06/2009:
Scenario Report: Hydrology (2 volumes)
Report 07/2009:
Scenario Report: Ecological and social predictions (4 volumes)
Report 08/2009:
Final Report
Other deliverables:
DSS Software
Process Management Team PowerPoint Presentations
Citation
No part of this document may be reproduced in any manner
without full acknowledgement of its source
This document should be cited as:
King, J.M. and Brown, C.A. 2009. Scenario Report (ecological and social) Volume 1 of 4.
Report 07-2009 EPSMO/BIOKAVANGO Okavango Basin Environmental Flows
Assessment Project, OKACOM, Maun, Botswana. 110 pp.
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E-Flows Ecological and Social Predictions Scenario Report
Acknowledgements
Many thanks for logistical support to:
· Corinne Spadaro of FAO)
· Ros Townsend, Karl Reinecke and Rembu Magoba of Southern Waters
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E-Flows Ecological and Social Predictions Scenario Report
Executive Summary
The Okavango River Basin Commission, OKACOM, initiated a project titled the
Environmental Protection and Sustainable Management of the Okavango River Basin
(EPSMO). This was approved by the United Nations Development Program (UNDP), to be
executed by the United Nations Food and Agriculture Organization (FAO). The standard
UNDP process is a Transboundary Diagnostic Analysis followed by a Strategic Action
Programme of joint management to address threats to the basin's linked land and water
systems. Because of the pristine nature of the Okavango River, this approach was modified
to include an Environmental Flow Assessment (EFA). To complete the EFA, EPSMO
collaborated with the BIOKAVANGO Project at the Harry Oppenheimer Okavango Research
Centre of the University of Botswana, in 2008 to conduct a basin-wide EFA for the Okavango
River system.
This is report number 7 (Volume 1) in the report series for the EFA. It details the three water-
resource development scenarios chosen for the project; the sites along the system; and the
70 indicators chosen to describe change. It then describes the predicted hydrological
change at each site under each scenario, and the response of the river under seven main
groups of biophysical indicators: channel geomorphology, water quality, vegetation, aquatic
invertebrates, fish, birds and wildlife. These river changes are then interpreted as impacts to
users of the river, using 12 indicators in four main groups: household incomes, wellbeing,
macro-economics and ecological services. It concludes with a discussion of important
aspects of the scenarios.
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E-Flows Ecological and Social Predictions Scenario Report
Table of Contents
1.
INTRODUCTION .............................................................................................. 14
1.1.
Project background ........................................................................................... 14
1.2.
Objectives of the EF assessment ..................................................................... 14
1.3.
Recap of process and earlier reports ................................................................ 15
1.3.1
Report 01/2009: Project Initiation Report ......................................................... 15
1.3.2
Report 02/2009: Process Report ..................................................................... 15
1.3.3
Report 03/2009: Guidelines for data collection, analysis and scenario creation
.......................................................................................................................... 15
1.3.4
Report 04/2009: Delineation Report ................................................................ 15
1.3.5
Report 05/2009: Hydrology Report: Data and models ..................................... 15
1.3.6
Report 06/2009: Scenario Report: Hydrology .................................................. 16
1.3.7
Report 07/2009: Scenario Report: Ecological and social predictions .............. 16
1.3.8
Report 08/2009: Final Report ........................................................................... 16
1.4.
The scenarios ................................................................................................... 16
1.5.
Limitations ......................................................................................................... 16
1.6.
Presentation of the results ................................................................................ 16
1.6.1
Rivers and delta ................................................................................................ 16
1.6.2
Societal wellbeing ............................................................................................. 16
1.7.
Economic value ................................................................................................ 17
1.8.
Layout of the report ........................................................................................... 18
2.
The EF sites/reaches and IUAs ........................................................................ 19
2.1.
The location of the ecological sites and links with IUAs ................................... 19
2.2.
Biophysical sites ............................................................................................... 21
2.2.1
Site 1: Cuebe River at Capico, ANGOLA ......................................................... 21
2.2.2
Site 2: Cubango River at Mucundi, ANGOLA ................................................... 22
2.2.3
Site 3: Cuito River at Cuito Cuanavale, ANGOLA ............................................ 23
2.2.4
Site 4: Okavango River at Kapako, NAMIBIA ................................................... 24
2.2.5
Site 5: Okavango River at Popa Falls, NAMIBIA .............................................. 25
2.3.
Site 6: Okavango River at the Panhandle, BOTSWANA .................................. 26
2.4.
Site 7: Okavango Delta at Xaxanaka, BOTSWANA ......................................... 28
2.5.
Site 8: Boteti River, BOTSWANA ..................................................................... 30
2.6.
Social IUAs ....................................................................................................... 31
2.7.
Indicators .......................................................................................................... 34
2.7.1
The nature and purpose of indicators ............................................................... 34
2.7.2
Biophysical indicators ....................................................................................... 34
2.7.3
Social indicators ................................................................................................ 35
3.
Water-use Scenarios ........................................................................................ 37
3.1.
Summary of the water-resource developments/abstractions that formed part of
each water-use scenario ..................................................................................................... 37
3.2.
Hydrological data generated for the scenarios ................................................. 40
3.3.
The ecologically-relevant summary statistics for the river sites (Sites 1-6) ...... 41
3.4.
Summary statistics for Site 7: Xaxanaka .......................................................... 44
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E-Flows Ecological and Social Predictions Scenario Report
3.5.
Summary statistics for Site 8: Boteti ................................................................. 45
3.6.
Process follow after the generation of ecological summary data ...................... 47
4.
Biophysical results: Disciplines ......................................................................... 48
4.1.
Introduction ....................................................................................................... 48
4.2.
Geomorphology ................................................................................................ 48
4.2.1
Indicator 1: Extent - exposed rocky habitat ....................................................... 48
4.2.2
Indicator 2: Extent coarse sediments ............................................................. 49
4.2.3
Indicator 3: Cross sectional area of channel ..................................................... 49
4.2.4
Indicator 4: Extent: backwaters ......................................................................... 49
4.2.5
Indicator 5: Extent: vegetated islands ............................................................... 50
4.2.6
Indicator 6: Sandbars at lowflow ....................................................................... 50
4.2.7
Indicator 7: Percentage clays and silts on floodplain ........................................ 50
4.2.8
Indicator 8: Extent: inundated floodplain ........................................................... 51
4.2.9
Indicator 9: Extent: pools and pans .................................................................. 52
4.2.10 Indicator 9: Extent: cut banks ........................................................................... 52
4.2.11 Indicator 10: Carbon storage ............................................................................ 52
4.2.12 Summary of geomorphological response to scenarios ..................................... 53
4.3.
Water Quality .................................................................................................... 53
4.3.1
Indicator 1: pH .................................................................................................. 53
4.3.2
Indicator 2: Conductivity ................................................................................... 54
4.3.3
Indicator 3: Temperature .................................................................................. 54
4.3.4
Indicator 4: Turbidity ......................................................................................... 54
4.3.5
Indicator 5: Dissolved oxygen ........................................................................... 55
4.3.6
Indicators 6, 7 and 8: Total nitrogen, total phosphorus and chlorophyll a ........ 55
4.3.7
Summary of water-quality responses to scenarios ........................................... 55
4.4.
Vegetation ......................................................................................................... 55
4.4.1
Indicator 1: Channel macrophytes (submerged) ............................................... 55
4.4.2
Indicator 2: Lower wet bank .............................................................................. 56
4.4.3
Indicator 3: Upper wetbank 1 (reeds) ............................................................... 56
4.4.4
Indicator 4: Upper wetbank 2 (trees/shrubs) ..................................................... 57
4.4.5
Indicator 5: River dry bank ................................................................................ 57
4.4.6
Indicator 6: Floodplain dry bank ........................................................................ 58
4.4.7
Indicator 7: River floodplain residual pools ....................................................... 58
4.4.8
Indicator 8: River lower floodplain ..................................................................... 59
4.4.9
Indicator 9: River middle floodplain ................................................................... 59
4.4.10 Indicator 10: River upper floodplain (islands) ................................................... 60
4.4.11 Delta (Site 7) Indicators .................................................................................... 60
4.4.12 Boteti (Site 8) Indicators ................................................................................... 62
4.4.13 Summary of vegetation responses to scenarios ............................................... 63
4.5.
Aquatic macroinvertebrates .............................................................................. 63
4.5.1
Indicator 1: Invertebrates in channel submerged vegetation ............................ 63
4.5.2
Indicator 2: Invertebrates in channel marginal vegetation ................................ 63
4.5.3
Indicator 3: Invertebrates in channel fine sediments ........................................ 63
4.5.4
Indicator 4: Invertebrates of channel cobbles and boulders ............................. 64
4.5.5
Indicator 5: Invertebrates of fast-flowing channels ........................................... 64
4.5.6
Indicator 6: Invertebrates in channel bedrock pools ......................................... 64
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E-Flows Ecological and Social Predictions Scenario Report
4.5.7
Indicator 7: Invertebrates of floodplain marginal vegetation ............................. 65
4.5.8
Indicator 8: Invertebrates of seasonal floodplain pools and backwaters .......... 65
4.5.9
Indicator 9: Invertebrates of mopane woodland pools ...................................... 65
4.5.10 Summary of aquatic invertebrate responses to scenarios ................................ 66
4.6.
Fish ................................................................................................................... 66
4.6.1
Indicator 1: Fish resident in river ....................................................................... 66
4.6.2
Indicator 2: Migratory floodplain dependent fish: small species ....................... 66
4.6.3
Indicator 3: Migratory floodplain dependent fish: large species ........................ 67
4.6.4
Indicator 4: Sandbank dwelling fish .................................................................. 68
4.6.5
Indicator 5: Rock dwelling fish .......................................................................... 68
4.6.6
Indicator 6: Marginal vegetation fish ................................................................. 69
4.6.7
Indicator 7: Backwater dwelling fish .................................................................. 69
4.6.8
Summary of fish responses to scenarios .......................................................... 69
4.7.
Wildlife .............................................................................................................. 70
4.7.1
Indicator 1: Semi aquatic animals. .................................................................... 70
4.7.2
Indicator 2: Frogs, snakes and small mammals. .............................................. 70
4.7.3
Indicator 3: Lower floodplain grazers ................................................................ 70
4.7.4
Indicator 4: Middle floodplain grazers ............................................................... 71
4.7.5
Indicator 5: Outer floodplain grazers ................................................................. 71
4.7.6
Summary of wildlife responses to scenarios ..................................................... 72
4.8.
Birds .................................................................................................................. 72
4.8.1
Indicator 1: Piscivores of open water. ............................................................... 72
4.8.2
Indicator 2: Piscivores of shallow waters .......................................................... 72
4.8.3
Indicator 3: Piscivores and invertebrate feeders ............................................... 73
4.8.4
Indicator 4: Specialists of floodplains ................................................................ 73
4.8.5
Indicator 5: Specialists of water-lily habitats ..................................................... 74
4.8.6
Indicator 6: Specialists inhabitants of riparian fruit trees .................................. 74
4.8.7
Indicator 7: Breeders in reedbeds and floodplains ........................................... 75
4.8.8
Indicator 8: Breeders in overhanging trees ....................................................... 75
4.8.9
Indicator 9: Breeders in banks .......................................................................... 76
4.8.10 Indicator 10: Breeders on rocks and sandbars ................................................. 76
4.8.11 Summary of bird responses to scenarios ......................................................... 77
5.
Biophysical results: Integrity ............................................................................. 78
5.1.
Integrity ratings and classification of overall impact .......................................... 78
5.2.
Present-day ecological integrity for the study sites ........................................... 79
5.3.
Interpretation of integrity plots .......................................................................... 81
5.4.
Effects on the integrity of each discipline .......................................................... 81
5.4.1
Geomorphology ................................................................................................ 81
5.4.2
Water Quality .................................................................................................... 82
5.4.3
Vegetation ......................................................................................................... 83
5.4.4
Aquatic macroinvertebrates .............................................................................. 84
5.4.5
Fish ................................................................................................................... 85
5.4.6
Wildlife .............................................................................................................. 87
5.4.7
Birds .................................................................................................................. 88
5.5.
Effects on the integrity of the whole ecosystem ................................................ 89
6.
Social results .................................................................................................... 91
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E-Flows Ecological and Social Predictions Scenario Report
6.1.
Introduction ....................................................................................................... 91
The chapter summarises the results for each of the socio-economic indicators in terms of
their overall contribution to the livelihoods of the people in the basin, as well as their
contribution to the economies of the basin countries. Livelihoods are measured in terms of
net income earned by households in the basin. Economic contributions are measured in
terms of the change in national income generated by the use of the indicators concerned.
............................................................................................................................................ 91
6.1.1
Indicator 1: Household income - fish ................................................................ 91
6.1.2
Indicator 2: Household reeds ............................................................................ 91
6.1.3
Indicator 3: Household income floodplain grass ............................................ 92
6.1.4
Indicator 4: Household income floodplain gardens (e.g. molapo) .................. 92
6.1.5
Indicator 5: Household income and wealth - livestock ...................................... 93
6.1.6
Indicator 6: Household income - tourism .......................................................... 93
6.1.7
Indicator 7: Potable water/water quality ............................................................ 94
6.1.8
Indicator 8: Wellbeing/welfare from intangibles ................................................ 94
6.1.9
Indicator 9.1: Macro-effects from tourism income, excluding household income
(including multipliers) ........................................................................................ 95
6.1.10 Indicator 9.2: Macro-effects from household income 1-6, (including multipliers,
etc) .................................................................................................................... 95
6.1.11 Indicator 9.3: Indirect use ................................................................................. 96
6.1.12 Indicator 9.4: Non-use ...................................................................................... 97
7.
Conclusions ...................................................................................................... 98
8.
References ..................................................................................................... 100
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E-Flows Ecological and Social Predictions Scenario Report
List of Figures
Figure 2.1 Map showing site locations and linked IUAs ........................................................ 19
Figure 2.2 Sketch map of the main channels in the Okavango Basin and the location of
the study sites. Channels not represented in the study are shown in black,
and those represented are in blue. ...................................................................... 20
Figure 2.3 Site 1: Cuebe River at Capico during the lowflow season (October 2008) .......... 21
Figure 2.4 Site 1: Cuebe River at Capico showing the gauging weir in the lowflow
season (October 2008) ........................................................................................ 21
Figure 2.5 Site 1: Cuebe River at Capico in the flood season (March 2008). Note the
top of the gauging weir in the middle of the picture. (Photo Helder André de
Andrade e Sousa) ................................................................................................ 22
Figure 2.6 Site 2: Cubango River at Mucundi in the lowflow season (October 2008) ........... 22
Figure 2.7 Site 2 Cubango River at Mucundi in the lowflow season (October 2008) ............ 23
Figure 2.8 Site 2: Cubango River at Mucundi in the flood season (March 2009; Photo
Helder André de Andrade e Sousa) ..................................................................... 23
Figure 2.9 Site 3: Cuito River at Cuito Cuanavale in the lowflow season (November
2007; Photo Manuel Quintino). ............................................................................ 24
Figure 2.10 Site 3: Cuito River at Cuito Cuanavale in the lowflow season (October 2008) .... 24
Figure 2.11 Site 4: Okavango River at Kapako in the lowflow season (October 2008). ......... 25
Figure 2.12 Cattle grazing on the floodplain at Site 4: Kapako in the lowflow season
(October 2008). .................................................................................................... 25
Figure 2.13 Site 5: Okavango River at Popa Falls in the lowflow season (October 2008) ...... 26
Figure 2.14 Aerial view of Site 5: Okavango River at Popa Falls in the lowflow season,
showing the whole reach. Flow direction is from right to left. (Photo: Colin
Christian) ............................................................................................................. 26
Figure 2.15 Site 6: Okavango River - erosion on bends in the Panhandle in the lowflow
season (October 2008) ........................................................................................ 27
Figure 2.16 Site 6: Marginal vegetation along the Okavango River in the Panhandle in the
lowflow season (October 2008) ........................................................................... 27
Figure 2.17 Site 6: Ungrazed floodplain along the Okavango River in the Panhandle
(October 2008) ..................................................................................................... 28
Figure 2.18 The Okavango Delta (Photo: Colin Christian) ...................................................... 28
Figure 2.19 Site 6: Okavango Delta at Xaxanaka in the lowflow season (October 2008)....... 29
Figure 2.20 Site 6: Backwater in the Okavango Delta at Xaxanaka in the lowflow season
(October 2008) ..................................................................................................... 29
Figure 2.21 Site 6: Heronry in the Okavango Delta at Xaxanaka in the lowflow season
(October 2008) ..................................................................................................... 30
Figure 2.22 Site 8: Boteti River, Okavango during the lowflow season (October 2008). ........ 30
Figure 2.23 Site 8: Lagoon on the Boteti River, Okavango during the lowflow season
(October 2008). .................................................................................................... 31
Figure 2.24 Site 8: Boteti River, Okavango, with animals, during the lowflow season
(October 2008). .................................................................................................... 31
Figure 2.25 Sketch map of the IUAs delineated in the Okavango Basin ................................ 33
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E-Flows Ecological and Social Predictions Scenario Report
Figure 4.1 Position of water-resource developments included in the water-use scenarios
in the upper portion of the catchment. ................................................................. 39
Figure 4.2 Position of water-resource developments included in the water-use scenarios
in the lower portion of the catchment. .................................................................. 40
Figure 4.3 Annual runoff data for Site 4: Kapako (1959-2001). ............................................ 41
Figure 4.4 Percentage of the 200-km study reach of the Boteti River that will be
inundated (wet); isolated pools (pool) and dry under the present-day
simulated conditions given climatic conditions that prevailed from 1973-2002.... 45
Figure 4.5 Percentage of the 200-km study reach of the Boteti River that will be
inundated (wet); isolated pools (pool) and dry under the low scenario given
climatic conditions that prevailed from 1973-2002. .............................................. 46
Figure 4.6 Percentage of the 200-km study reach of the Boteti River that will be
inundated (wet); isolated pools (pool) and dry under the medium scenario
given climatic conditions that prevailed from 1973-2002. .................................... 46
Figure 4.7 Percentage of the 200-km study reach of the Boteti River that will be
inundated (wet); isolated pools (pool) and dry under the high scenario given
climatic conditions that prevailed from 1973-2002. .............................................. 47
Figure 4.8 Summary of process within the DSS ................................................................... 47
Figure 5.1 Relationship between flood season volume and area of floodplain inundated
for Site 4: Kapako. ............................................................................................... 51
Figure 5.2 Proportions of the vegetation indicators in the study area over a 20-year
period under present-day conditions. .................................................................. 61
Figure 5.3 Proportions of the vegetation indicators in the study area over a 20-year
period under the low scenario. ............................................................................. 61
Figure 5.4 Proportions of the vegetation indicators in the study area over a 20-year
period under the medium scenario. ..................................................................... 61
Figure 5.5 Proportions of the vegetation indicators in the study area over a 20-year
period under the medium scenario. ..................................................................... 62
Figure 6.1 Integrity plot for geomorphology for the three scenarios at each of the study
sites ..................................................................................................................... 81
Figure 6.2 Integrity plot for water quality for the three scenarios at each of the study
sites ..................................................................................................................... 82
Figure 6.3 Integrity plot for vegetation for the three scenarios at each of the study sites ..... 84
Figure 6.4 Integrity plot for aquatic macroinvertebrates for the three scenarios at each of
the study sites ...................................................................................................... 85
Figure 6.5 Integrity plot for fish for the three scenarios at each of the study sites ................ 86
Figure 6.6 Integrity plot for wildlife for the three scenarios at each of the study sites ........... 87
Figure 6.7 Integrity plot for birds for the three scenarios at each of the study sites .............. 88
Figure 6.8 Overall ecosystem integrity for the three scenarios at each of the study sites .... 89
Figure 6.9 Summary of expected changes in ecosystem integrity for the low, medium
and high scenarios. Present-day conditions are estimated as B-category. ........ 91
All photographs that are not acknowledged in the text are by J.M. King and C.A. Brown.
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E-Flows Ecological and Social Predictions Scenario Report
List of Tables
Table 2.1 The Environmental Flow (EF) sites and their corresponding socio-economic
Integrated Unit of Analysis (IUA) ......................................................................... 20
Table 3.1 Biophysical indicators used in the EPSMO/BIOKAVANGO EF process.............. 34
Table 4.1 The hypothetical water-resource developments included in each scenario ......... 37
Table 4.2 Median values for the ecologically-relevant summary statistics for each
scenario for Site 1: Capico. PD = simulated present day flow regime. L = low
scenario; M = medium scenario; and H = high scenario. ..................................... 42
Table 4.3 Median values for the ecologically-relevant summary statistics for each
scenario for Site 2: Mucundi. PD = simulated present day flow regime. L =
low scenario; M = medium scenario; and H = high scenario. .............................. 42
Table 4.4 Median values for the ecologically-relevant summary statistics for each
scenario for Site 3: Cuito Cuanavale. PD = simulated present day flow
regime. ................................................................................................................. 43
Table 4.5 Median values for the ecologically-relevant summary statistics for each
scenario for Site 4: Kapako. PD = simulated present day flow regime. L =
low scenario; M = medium scenario; and H = high scenario. .............................. 43
Table 4.6 Median values for the ecologically-relevant summary statistics for each
scenario for Site 5: Popa Falls and Site 6: Panhandle. PD = simulated
present day flow regime. L = low scenario; M = medium scenario; and H =
high scenario. ...................................................................................................... 44
Table 4.7 Vegetation types used in the model ..................................................................... 44
Table 4.8 Mean percentage of cover for vegetation types in the area of the Delta
represented by Site 7, for simulated present-day conditions, and for the low,
medium and high scenarios. ................................................................................ 44
Table 6.1. The South African River Categories (DWAF 1999) ............................................. 78
Table 6.2 Criteria and weights used for the assessment (from Kleynhans 1996)................ 79
Table 6.3 Results of the Habitat Integrity (after Kleynhans 1996) assessments done on-
site by the biophysical specialists at each of the study sites (October 2008) ...... 80
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E-Flows Ecological and Social Predictions Scenario Report
Acronyms and abbreviations
DWAF
Department of Water Affairs and Forestry
EFA
Environmental Flow Assessment
EPSMO
Environmental Protection and Sustainable Management of the Okavango
River Basin
Ha hectare
HOORC
Harry Oppenheimer Okavango Research Centre
IUA
Integrated Units of Analysis
PD Present
Day
SAP
Strategic Action Programme
TDA
Transboundary Diagnostic Analysis
13
1. INTRODUCTION
1.1. Project
background
The origin of the project is described in Report 01/2009: Project Initiation Report. Essentially,
an OKACOM initiative titled the Environmental Protection and Sustainable Management of
the Okavango River Basin (EPSMO) project was approved by the United Nations
Development Program (UNDP), to be executed by the United Nations Food and Agriculture
Organization (FAO). In 2008 it collaborated with the Biokavango Project at the Harry
Oppenheimer Okavango Research Centre (HOORC) of the University of Botswana, to
conduct a basin-wide Environmental Flows Assessment (EFA) for the Okavango River
system. This would be a major part of a standard UNDP process: a Transboundary
Diagnostic Analysis (TDA) followed by a Strategic Action Programme (SAP) of joint
management to address threats to the basin's linked land and water systems. In the case of
the Okavango Basin, the standard approach, designed for rehabilitating degraded rivers,
would be modified because of the near-pristine nature of the river ecosystem.
The EFA began with a Planning Meeting in July 2008 and was finalised in June 2009. It
used mainly existing knowledge and understanding of the river ecosystem and its users. It
was generally acknowledged that this was a first, low-confidence, trial run of an EFA for this
system, which should be followed by a more comprehensive and long-term exercise where
important missing data and knowledge could be addressed to provide higher-confidence
predictions.
1.2.
Objectives of the EF assessment
There were two main objectives.
· Complete a basin-wide EFA of the Okavango River system as a major part of the
wider Technical Diagnostic Analysis. This would be done through several subsidiary
objectives:
o Collate all existing hydrological data on the river system and set up a basin
hydrological model that could simulate flows under various possible future
development scenarios
o Reach agreement with the three riparian governments on the scenarios to be
explored
o Bring together specialists in a range of relevant disciplines from across the
basin to share knowledge and data, and reach consensus on the:
relationships between flow and a series of biophysical indicators of the
river system
relationships of the condition of the ecosystem and social indicators
o Develop a DSS that would capture these relationships and produce
predictions of ecological and social change for each scenario that would
complement the macroeconomic predictions emanating from a separate
exercise
o Incorporate the EFA findings in the TDA document.
· Promote basin-wide communication and collaboration, and build capacity in
collaborative basin-wide Integrated Water Resource Management in all disciplines in
all three countries. This was done by appointing a full biophysical and socio-
economic team from each of the three countries, with planning, coordination and
training done by a Process Management Team.
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E-Flows Ecological and Social Predictions Scenario Report
1.3.
Recap of process and earlier reports
The EFA ran over 12 months, from July 2008 to June 2009. The principal features and their
timing were:
· a Planning Meeting (July 2008)
· a Basin Delineation Workshop (September 2008)
· a basin field trip (October 2008)
· a series of hydrological team meetings (September 2008 to May 2009)
· specialist discipline studies and report writing (November 2008 to May 2009)
· development of Decision Support System (DSS) software to capture the specialists'
knowledge (November 2008 to May 2009)
· a Knowledge Capture Workshop (April 2009)
· a Scenario Workshop (May 2009).
The full report series produced by the EFA is listed at the beginning of this report, with a
summary of the contents of each detailed below.
1.3.1
Report 01/2009: Project Initiation Report
Details the origin of the project, including the July 2008 Planning Meeting and the agreed
work plan.
1.3.2
Report 02/2009: Process Report
Describes the technical process followed in the EFA, including the division of the basin into
homogeneous units and choosing of representative sites, the data collection and knowledge
capture exercises, the hydrological modeling, the choice of indicators with which to describe
expected development-driven change, and the nature of the DSS.
1.3.3
Report 03/2009: Guidelines for data collection, analysis and scenario
creation
A set of guidelines for basin delineation; site selection, estimating ecological condition of the
sites, scenario selection, indicator selection, data collection, Response Curves construction
(these describe the flow-ecosystem and ecosystem-social impact relationships), and report
writing.
1.3.4 Report
04/2009:
Delineation Report
The results of the September 2008 workshop, containing the following: basin location and
characteristics; river zonation; delta zonation; socio-economic zonation; Integrated Units of
Analysis; and selected study sites/zones. Eight representative sites were chosen along the
system: three in Angola, two in Namibia and three in Botswana. Each would be linked to
specific socio-economic areas so that the predictions of river change could be interpreted as
predictions of social impact.
1.3.5
Report 05/2009: Hydrology Report: Data and models
The initial work of the three-country hydrological team and the international basin hydrologist,
including choosing and setting up the hydrological and hydraulic models, field data collection,
hydrological and geohydrological data and information, water-resource development
information, and data and information sharing arrangements.
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E-Flows Ecological and Social Predictions Scenario Report
1.3.6
Report 06/2009: Scenario Report: Hydrology
Details the initial part of the scenario descriptions, including the scenarios chosen, and the
hydrological outcomes for all eight sites along the system.
1.3.7
Report 07/2009: Scenario Report: Ecological and social predictions
This report.
1.3.8
Report 08/2009: Final Report
A short report of the project for contractual purposes.
1.4. The
scenarios
Through a process of government consultation, three scenarios of increasing water-use were
chosen for the EFA. The details are provided in Report 06/2009: Scenario Report:
Hydrology, and in Chapter 3 of this report.
1.5. Limitations
The project faced financial, time and knowledge constraints that influenced its outputs. The
major of these limitations were as follows:
· A limited budget, which resulted in various important parts of the process having to be
excluded, such as training exercises at key points in the process, in-depth review of the
specialist reports and production of a glossy information brochure in accessible language
for water managers and decision makers.
· Limited warning of the project beginning, which meant that all team members were over-
committed throughout the project.
· Limited time to complete the work, which meant that the project ran on available data and
general expert knowledge of the system; virtually no new data were collected, even
where uncertainty was extremely high.
Despite this, the project stimulated a very strong and constructive team spirit and an inter-
basin collaboration that appears set to continue long after it ends.
1.6.
Presentation of the results
1.6.1
Rivers and delta
For each scenario, the predicted changes in the river and delta are evaluated in three ways:
1. time-series of abundance, area or concentration of key indicators (see list in Chapter
2.7) under the flow regime resulting from each scenario (Appendix 2);
2. estimated mean percentage changes from present day in the abundance, area or
concentration of key indicators (Appendix 2, with a summary in Chapter 4);
3. estimated change in discipline-specific integrity, relative to present day (Section 5.4)
4. estimated change in overall ecological integrity, relative to present day (Section 5.5.
1.6.2 Societal
wellbeing
The impact on local communities is assessed in terms of changes in wellbeing as a result of
the changes in tangible and intangible benefits derived from the use of water and aquatic
ecosystem resources. These changes are expressed as:
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E-Flows Ecological and Social Predictions Scenario Report
· Change in household income from agricultural activities likely to be affected by
change in water flow,
· Change in household income from natural resources use likely to be affected by
water flow.
These values include own consumption of products and cash income. They include the net
incomes (profits) derived by community members while using natural resources, as well as
wages and salaries derived by them from employment in natural resource use, e.g., tourism.
These values are summed to estimate overall change income, and reflect the contribution
made by river/wetland resources to livelihoods in the basin. Then the impact of water use
scenarios on these values is measured, using the EFA model, for each IUA in the basin, for
each of the three countries, and for the basin as a whole.
All livelihood values are expressed as the aggregate for all households in the affected area.
The overall value is expressed as a percentage change in overall household income, taking
all other sources of household income into account. Note that the percentage change might
not apply to individual households, since this value might be shared by more households
under an expanded population.
Other measures of societal well being are those that impact on the broader society in each
country. These include the impact of the natural resources use described above in the
national income, including income not just for community members, but also for all other
stakeholders in society. National income change is a macroeconomic measure as linking up
with the economic values in 1.7, below. Other broader measures for societal wellbeing which
were assessed include indirect use values derived from ecosystem services in the wetlands.
These include the value derived from carbon storage, water purification, core wildlife refuge
values, and so on. Intangible impacts as reflected in existence value and cultural value are
expressed as the percentage change in overall recreational and spiritual wellbeing, taking
other intangible sources of wellbeing into account.
1.7. Economic
value
In a separate exercise, the same three development scenarios were assessed in terms of
their development benefits. This involved assessment of the macroeconomic impacts of
water use developments in the scenarios, including those of hydropower, irrigation, and
water extraction for domestic and urban use. These macroeconomic benefits as measured
in change to the national income, were assessed in comparison to the losses in national
income from flow related river/wetland natural resource uses as measured in the EFA model.
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E-Flows Ecological and Social Predictions Scenario Report
1.8.
Layout of the report
Chapter 1:
Introduction
Chapter 2:
Location and description of the EF sites
Chapter 3:
A listing and explanation of the indicators
Chapter 4:
A description of the chosen scenarios in terms of the location and
specifications of each chosen water-resource development, a summary of the
changes in the flow regime under each scenario at each site
Chapter 5:
The predictions of biophysical change per scenario
Chapter 6:
The predictions of overall change in ecosystem integrity, per scenario
Chapter 7:
The predictions of socio-economic change
Chapter 8:
Conclusions
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E-Flows Ecological and Social Predictions Scenario Report
2.
The EF sites/reaches and IUAs
2.1.
The location of the ecological sites and links with IUAs
The number, and to some extent the position, of the eight biophysical sites was dictated by
financial, time and safety constraints, and they did not represent the entire basin. The
locations of the eight sites, chosen in an exercise described in Report 04/2009: Delineation
Report, are given in Table 2.1 and Figure 2.1. These sites are described in Section 2.2.
Each biophysical site corresponded to a wider, socio-economic Integrated Unit of Analysis
(IUA), where it was used to represent the predicted river changes that would affect people.
These IUAs are described in Section 2.3.
Figure 2.1
Map showing site locations
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E-Flows Ecological and Social Predictions Scenario Report
Table 2.1
The Environmental Flow (EF) sites and their corresponding socio-economic
Integrated Unit of Analysis (IUA)
EF
EF Site name
Coordinates Socio-economic
IUA
Site
1
Cuebe @ Capico
15° 33' 05" S
3
17° 34' 00" E
2
Cubango @ Mucundi
16° 13' 05" S
2
17° 41' 00" E
3
Cuito @ Cuito Cuanavale
15° 10' 11" S
6
19° 10' 06" E
4 Okavango
@
Kapako
17° 49' 07" S
8
19° 11' 44" E
5
Okavango @ Popa Falls
18° 07' 02" S
9
21° 35' 03" E
6 Okavango
@
Panhandle
18° 21' 16" S
10
21° 50' 13" E
7
Okavango Delta @ Xaxanaka
19° 11' 09" S
11
23° 24' 48" E
8 Boteti
20° 12' 51" S
12
24° 07' 37" E
The location of the study sites resulted in portions of the catchment for which no predictions
were possible in this study. These are indicated in Figure 2.2.
1
3
2
5
7
4
6
8
Figure 2.2
Sketch map of the main channels in the Okavango Basin and the location of the
study sites. Channels not represented in the study are shown in black, and
those represented are in blue.
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E-Flows Ecological and Social Predictions Scenario Report
2.2. Biophysical
sites
2.2.1
Site 1: Cuebe River at Capico, ANGOLA
Location:
At Capico on the Cuebe River, Angola.
River reach:
Cuebe River from downstream of Menongue to the confluence with the
Cubango River.
Photographs:
Figure 2.3 - Figure 2.5.
Figure 2.3
Site 1: Cuebe River at Capico during the lowflow season (October 2008)
Figure 2.4
Site 1: Cuebe River at Capico showing the gauging weir in the lowflow season
(October 2008)
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.5
Site 1: Cuebe River at Capico in the flood season (March 2008). Note the top of
the gauging weir in the middle of the picture. (Photo Helder André de Andrade e
Sousa)
2.2.2
Site 2: Cubango River at Mucundi, ANGOLA
Location:
At Mucundi on the Cubango River, Angola.
River reach:
Cubango River from downstream of confluence with the Cuebe River to the
Namibian border.
Photographs:
Figure 2.6 - Figure 2.8.
Figure 2.6
Site 2: Cubango River at Mucundi in the lowflow season (October 2008)
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.7
Site 2 Cubango River at Mucundi in the lowflow season (October 2008)
Figure 2.8
Site 2: Cubango River at Mucundi in the flood season (March 2009; Photo
Helder André de Andrade e Sousa)
2.2.3
Site 3: Cuito River at Cuito Cuanavale, ANGOLA
Location:
At Cuito Cuanavale on the Cuito River.
River reach:
Cuito River from downstream of confluence with the Cuanavale River to
downstream of Cuito Cuanavale.
Photographs:
Figure 2.9 and Figure 2.10.
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.9
Site 3: Cuito River at Cuito Cuanavale in the lowflow season (November 2007;
Photo Manuel Quintino).
Figure 2.10
Site 3: Cuito River at Cuito Cuanavale in the lowflow season (October 2008)
2.2.4
Site 4: Okavango River at Kapako, NAMIBIA
Location:
At Kapako on the Okavango River, Namibia.
River reach:
Okavango River from Kitwetwe to Rundu.
Photographs:
Figure 2.11 and Figure 2.12
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.11
Site 4: Okavango River at Kapako in the lowflow season (October 2008).
Figure 2.12
Cattle grazing on the floodplain at Site 4: Kapako in the lowflow season
(October 2008).
2.2.5
Site 5: Okavango River at Popa Falls, NAMIBIA
Location:
At Popa Falls on the Okavango River, Namibia.
River reach:
Okavango River at Popa Falls.
Photographs:
Figure 2.13 and Figure 2.14.
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.13
Site 5: Okavango River at Popa Falls in the lowflow season (October 2008)
Figure 2.14
Aerial view of Site 5: Okavango River at Popa Falls in the lowflow season,
showing the whole reach. Flow direction is from right to left. (Photo: Colin
Christian)
2.3.
Site 6: Okavango River at the Panhandle, BOTSWANA
Location:
At Drotsky's Fishing Camp in the Panhandle, Botswana.
River reach:
Okavango River at the Panhandle.
Photographs:
Figure 2.15 to Figure 2.17.
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.15
Site 6: Okavango River - erosion on bends in the Panhandle in the lowflow
season (October 2008)
Figure 2.16
Site 6: Marginal vegetation along the Okavango River in the Panhandle in the
lowflow season (October 2008)
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.17
Site 6: Ungrazed floodplain along the Okavango River in the Panhandle
(October 2008)
2.4.
Site 7: Okavango Delta at Xaxanaka, BOTSWANA
Location:
At Xakanaka in the western portion of the Okavango Delta, Botswana
River reach:
Western portion of the Okavango Delta.
Photographs:
Figure 2.18 to Figure 2.21.
Figure 2.18
The Okavango Delta (Photo: Colin Christian)
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.19
Site 6: Okavango Delta at Xaxanaka in the lowflow season (October 2008)
Figure 2.20
Site 6: Backwater in the Okavango Delta at Xaxanaka in the lowflow season
(October 2008)
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.21
Site 6: Heronry in the Okavango Delta at Xaxanaka in the lowflow season
(October 2008)
2.5.
Site 8: Boteti River, BOTSWANA
Location:
Boteti River, Botswana.
River reach:
Boteti River from the confluence with the Talamakane River for 200 km
downstream.
Photographs:
Figure 2.22 - Figure 2.24.
Figure 2.22
Site 8: Boteti River, Okavango during the lowflow season (October 2008).
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E-Flows Ecological and Social Predictions Scenario Report
Figure 2.23
Site 8: Lagoon on the Boteti River, Okavango during the lowflow season
(October 2008).
Figure 2.24
Site 8: Boteti River, Okavango, with animals, during the lowflow season
(October 2008).
2.6. Social
IUAs
The delineation report (04/2009) describes the process of delineation of IUAs after
consideration of all biophysical and socio-economic features of the basin. The final
delineation can be described in terms of the socio-economic characteristics as the socio-
31
E-Flows Ecological and Social Predictions Scenario Report
economic impacts generally come last and effectively tie up the results of the EFA model.
Figure 2.25 shows the 12 IUAs schematically.
Angolan IUAs 1 to 4 were delineated in the Cubango arm of the basin. In the Cubango arm,
floodplains are rare and river courses are relatively incised. The basement geology has
mostly been exposed, leaving little Kalahari sand cover. The IUAs here were delineated on
the basis of topography, ecology, population density, urbanisation and the future likely water
use developments. Thus, IUA 1 covered the high rainfall, high altitude upper reaches where
parallel tributaries drain an open upland savanna, the soils are medium textured, and there is
a high density of people. Rainfed crop production with maize is the most important land use.
IUA 2, including the town of Cuchi, was similar but lower, less incised, slightly drier, slightly
less densely settled and it contains small areas of Kalahari sand woodlands. It contained
field study site 2, at Mucundi. IUA 3 was specific to the Cuebe River catchment and included
the city of Menongue. Here the situation was similar to that of IUA 2 but there were some
water quality issues surrounding the city, and there was some irrigation of crops and plans
for much more. The field study site 1 at Capico was included here.
Angolan IUAs 5 to 7 were delineated for the Cuito arm of the basin. These were relatively
uninhabited, pristine, and occupied by Kalahari sand woodlands. Floodplains were more
significant here than in the Cubango arm, and water flow variation was much more
seasonally stable. The three IUAs here were separated on the grounds of rainfall (from
humid to semi-arid), on the basis of crops grown (cassava is the main crop grown in the
upper part), the presence of an urban area (Cuito Cuanavale) and on the basis of future
water use developments (likely to be in the lower reaches). Field study site 3 at Cuito, was
situated in IUA 6.
Two IUAs, each with two subdivisions, were defined for Namibia, based on the presence or
absence of a floodplain, flooding regime, and whether or not there was a human population.
IUA 8 covered the river along the Angolan border, where human population density was high
and a moderate floodplain was present. It contained the urban area of Rundu, and field
study site 4 at Kapako. It was subdivided between the parts above and below the Cuito
junction, which differed slightly in terms of seasonal flow regime. IUA 9 covered the river
below Mukwe, where a floodplain was mostly absent and some rocky exposures occurred in
the river bed. IUA 9 was subdivided into that section with a resident human population and
that which was protected as Bwabwata National Park. It contained field study site 5 at Popa.
Three IUAs were defined for the Botswana part of the basin, based primarily of flooding
patterns. IUA 10 formed the panhandle with a fairly wide, mostly permanently flooded plain
and a moderately dense, relatively ethnically distinct human population. It contained field
study site 6 at Mohembo. Fishing, and non-floodplain crops were characteristic. IUA 11
covered most of the Delta with a complex pattern of seasonal, permanent, frequent, and
occasional flooding. It contained two subdivisions; moderately dense human settlement in
the west, and natural protected areas used mostly for tourism in the north east. Field study
site 7 at Xakanaka was in the latter subdivision. IUA 12 covered the most distal part of the
active basin and as such contained ephemeral channels and more restricted, less commonly
flooded floodplain. Fairly dense human settlement was present here including the urban
centre of Maun. It contained field study site 8 at Boteti. Five additional IUAs, numbers 13 to
17 were classified to refer to larger urban areas, in case these could be of use in the EFA
process. These were embedded within the other IUAs and not delineated spatially.
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E-Flows Ecological and Social Predictions Scenario Report
Figure 0.15
Sketch map of the IUAs delineated in the Okavango Basin
33
E-Flows Ecological and Social Predictions Scenario Report
2.7. Indicators
2.7.1
The nature and purpose of indicators
In this EFA two kinds of indicators are used: biophysical and socioeconomic. They represent
attributes of the ecological and social system that are thought to be either directly or indirectly
linked to the river and its flow regime. Their predicted changes as flows change provide a
composite picture of the ecological and social impacts of the chosen water-resource
developments.
2.7.2 Biophysical
indicators
Biophysical indicators are attributes of the river ecosystem that can be described in terms of
abundance (e.g. number of elephants), area (e.g. area of exposed sand banks),
concentration (e.g. nitrates, conductivity) or cover (e.g. vegetation communities.
Those chosen by the biophysical team for use in this project are listed in Table 0.1.
Table 0.1
Biophysical indicators used in the EPSMO/BIOKAVANGO EF process
Discipline Sites
Indicators
used
Extent - exposed Rocky Habitat
Extent - Coarse Sediments
Cross Sectional Area of Channel
Extent of Backwaters
Extent of Vegetated Islands
1-6
Geomorphology
Sand Bars at low flow
Percentage Clays on Floodplain
Extent of inundated floodplain
Inundated Pools and Pans
Extent of Cut Banks
7 Carbon
sequestration
pH
Conductivity
Temperature
Turbidity
Water Quality
1-8
Dissolved oxygen
Total nitrogen
Total phosphorus
Chlorophyll a
Channel macrophytes
Lower Wet Bank (hippo grass, papyrus)
Upper Wet Bank 1 (reeds)
Upper Wet Bank 2 (trees, shrubs)
River Dry Bank
1-6
Floodplain Dry Bank
Floodplain residual pools
Lower floodplain
Middle floodplain (grasses)
Vegetation
Upper floodplain (trees,)
Open waters
Permanent swamps
Lower floodplain
Upper floodplain
7
Occasionally flooded grassland
Sporobolus islands
Riparian woodland, trees
Savanna and scrub
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E-Flows Ecological and Social Predictions Scenario Report
Discipline Sites
Indicators
used
Open water
8
Riparian woodland, trees
Channel-submerged vegetation
Channel-marginal vegetation
Channel-fine sediments
Channel-cobbles, boulders
1-8
Macroinvertebrates
Channel rapid, fast flowing
Channel-pools
Floodplain-marginal vegetation
Floodplain-pools, backwaters
Plus for 7
Mopane woodland-pools
Fish resident in river
Migrate floodplain small fish
Migrate floodplain large fish
Fish 1-8
Fish-sandbank dweller
Fish-rock dweller
Fish-marginal vegetation
Fish in backwaters
Semi Aquatics (hippos, crocodiles)
Frogs, river snakes
Wildlife 1-8
Lower floodplain grazers
Middle floodplain grazers
Outer floodplain grazers
Piscivores - open water
Piscivores - shallow water
Piscivores and invertebrate feeders
Specialists - floodplains
Specialists - water lilies
Birds 1-8
Specialists - fruit trees
Breeders - reedbeds, floodplains
Breeders - overhanging trees
Breeders - banks
Breeders - rocks, sandbars
In the EFA process (Report 02/2009: Process Report), specialists draw Response Curves
that describe the relationship between each indicator and each relevant part of the flow
regime (Section 3.3).
2.7.3 Social
indicators
The economic activities in the basin were identified and described. They were then
examined and assessed to select those that might exhibit measurable value change if the
river/wetland system would be subjected to flow change. These were then used as the
socio-economic indicators in the EFA process. Figure 2.26 shows the full list of socio-
economic indicators. Most indicators are applicable to all of the eight field study sites and 12
IUAs in the basin. The exceptions apply where, for example, there is no floodplain of
significance, and thus no floodplain grazing or floodplain crop production, or where, for
example, there are no resident people.
It is important to stress that the indicators selected are limited to values that are expected to
change under differing water use scenarios. Some natural resource uses associated with the
riverine environment provide livelihood and economic value but are unlikely to change with
flow change. An example is use of riparian tree fruits, and another is irrigated commercial
agricultural production. Some 2,600 hectares are irrigated in this way in the Namibian basin,
contributing significant income and employment for local residents. But irrigated crop
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E-Flows Ecological and Social Predictions Scenario Report
production draws water regardless of flow change. New irrigation will also form part of water
use development scenarios, itself affecting water flow.
Indicator
1. Household income - fish
2. Household income - reeds
3. Household income - floodplain grass
Total income
a. Household income
change as %
4. Household income - floodplain gardens (e.g. molapo)
%PD
g
PD
n
A. SOCIAL WELL-
5. Household income and wealth - livestock
BEING FOR
l
-
bei
LOCAL
6. Household income - tourism
HOUSEHOLDS
i
c
wel
(=a+b+c)
b. Potable
7. Potable water/water quality
water/water quality
-
econom
%PD
cio
c. Wellbeing/welfare
l so
8. Wellbeing/welfare from intangibles
from intangibles %Pd
Overal
9.1 Macro effects from tourism income excluding hh
(including multipliers)
(=A+B).
9.2 Macro effects from hh income 1-6 (including
d. National income
B. ECONOMIC-
C
multipliers etc.)
(=9.1+9.2+9.3+9.4)
WELL BEING
%PD
(nationally)
9.3 Indirect use
9.4 non-use
Figure 2.26: List of socio-economic indicators used in the EFA and their links to the broader
economy
Possible indicators affecting human wellbeing are those related to health and disease, such
as malaria, bilharzia and diarrhoea, were examined. Although their incidence is linked to the
aquatic environment these were found to not be affected specifically by flow change. Other
possible indicators included natural resource uses such as water lily use (Nymphaea sp.) for
food, and use of the sedge (Cyperus papyrus) for mat making, were rejected as indicators
either because they were considered of small import or because in some sites their use was
unlikely to be affected by flow changes. Further, not all indicators have been assigned
values. Where data are unavailable some relatively minor resources have been treated only
in discussion, despite being recognised as possibly responsive to flow change.
The indicators in Figure 2.26 are divided firstly into those affecting both local household
income, or livelihoods (indicators 1 to 8) and the broader economy, and secondly those
impacting directly on the broader economy or on societal well-being (9.1 to 9.4). The table
shows how these all contribute ultimately to overall social and economic wellbeing.
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E-Flows Ecological and Social Predictions Scenario Report
3. Water-use
Scenarios
Three scenarios were selected for analysis, each representing an hypothetical level of water-
resource development in the Okavango Basin: low, medium or high.
The process for scenario selection is described in Report 02/2009: Process Report. Water-
use scenarios are not situations that will happen; rather, they are combinations of possible
future water-resource developments that can be explored in terms of their implications, as an
aid to planning and decision-making.
The outcomes of scenarios depend on what is included as a water-resource development.
Changing the location, size or any other aspects of a possible development will change the
expected future flow regime and thus the expected ecological and social implications.
3.1. Summary
of
the
water-resource developments/abstractions that
formed part of each water-use scenario
The hypothetical water-resource developments/abstractions that formed part of each water-
use scenario are summarised in Table 3.1 and displayed in Figure 3.1 and Figure 3.2.
Table 3.1
The hypothetical water-resource developments included in each scenario
Medium High
Site Present
Low
Low schemes plus:
High schemes plus:
Menongue: 246 000
Menogue: 257 000
Menogue: 30 000
Menogue: 70 000
people
people
people
people
Site 1
Irrigation: Missombo 1000 ha, weir diversion
Capico
Irrigation: Menongue Agriculture 10 000 ha, pump sump on river bank
Irrigation: Ebritex 17 000 ha, pump sump on river bank
HEP: Liapeca, run-of-river, low weir, turbines d/s
ALL CAPICO DEVELOPMENTS PLUS:
HEP: Cuvango Existing / not functioning. Rehabilitation in 2009. 40m
high reservoir, 1250 Mm3, Qmax = 3.5 m3/s
HEP: Cuchi (Kaquima (Malobas)). Run-of-river. H = 14m, Qmax = 3
m3/s
HEP: Maculungungu (on Cubango u/s Caiundo). Run-of-river. H = 22m,
Qmax = 24 m3/s
Site 2
HEP: Cutato. Run-of-
Mucundi
river. H = 30m, Qmax =
6 m3/s
HEP: Rapides do
Cuelei. Run-of-river. H =
22m, Qmax = 8 m3/s
Irrigation: Cuchi, 15 000 Irrigation: Cuchi, 150 000 ha, pump intake
ha, pump intake
Irrigation : Cuvango, 10 000 ha, pump sump on
river bank
Site 3
Cuito Cuanavale: 110 Cuito Cuanavale: 115 Cuito Cuanavale: 128 Cuito Cuanavale: 160
Cuito
435 people
000 people
600 people
000 people
Cuanavale
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E-Flows Ecological and Social Predictions Scenario Report
Medium High
Site Present
Low
Low schemes plus:
High schemes plus:
HEP: Cuito Cuanavale (13 km u/s confluence).
Diversion, Run-of-river. H = 7m, Qmax = 90 m3/s
ALL CAPICO & MUCUNDI DEVELOPMENTS PLUS:
Irrigation: Kahenge 300 Irrigation: Kahenge 700 Irrigation: Kahenge 900 ha, pump intake on river
ha, pump intake on river ha, pump intake on river bank
Site 4
bank
bank
Kapako
Irrigation: Rundu Future 1100 ha, pump intake
on river bank
Irrigation: Cuangar
Calais 45 000 ha, pump
intake on river bank
ALL CAPICO, MUCUNDI, KAPAKO AND CUITO CUANAVALE DEVELOPMENTS PLUS:
Irrigation: Longa 10 000 ha, pump intake on river
bank
Irrigation: Calais Dirico
35 000 ha, pump intake
on river bank
Irrigation: Calais Dirico
B 60 000 ha, pump
intake on river bank
Irrigation: Mukwe 560 ha, pump intake on river bank
Irrigation: Rundu-
Mashare 521 ha, pump Irrigation: Rundu-Mashare 551 ha, pump intake on river bank
intake on river bank
Irrigation: Ndiyona 870
ha, pump intake on river Irrigation: Ndiyona 1270 ha, pump intake on river bank
Site 5&6
bank
Popa and
Panhandle Rundu Urban, Tower on Rundu Urban, Tower on Rundu Urban, Tower on Rundu Urban, Tower on
right bank, 2.8 Mm3/a right bank, 3.0 Mm3/a right bank, 3.4 Mm3/a right bank, 4.3 Mm3/a
Irrigation: Mukwe Future Irrigation: Mukwe Future
4000 ha, pump intake 10 600 ha, pump intake
on river bank
on river bank
Eastern National Carrier Eastern National Carrier
(ENC) for water supply (ENC) for water supply
from Kavango to
from Kavango to
Namibia, Tower on right Namibia, Tower on right
bank, 17 Mm3/a
bank, 100 Mm3/a
HEP: Popa Falls. Run-
of-river, Weir at Site 2.
H = 7.5 m, Qmax = 280
m3/s, 22.5 Mm3
capacity.
HEP: Cuito M'Pupa.
Run-of-river. H = 5m,
Qmax = 100 m3/s
38
E-Flows Ecological and Social Predictions Scenario Report
Medium High
Site Present
Low
Low schemes plus:
High schemes plus:
HEP: Cuito
Chamavera (d/s
M'Pupa). Run-of-river. H
= 6m, Qmax = 100 m3/s
Site 7
ALL CAPICO, MUCUNDI, KAPAKO, CUITO CUANAVALE AND POPA/PANHANDLE
Khwai
DEVELOPMENTS
ALL CAPICO, MUCUNDI, KAPAKO, CUITO CUANAVALE, POPA/PANHANDLE
Site 8
DEVELOPMENTS, PLUS:
Boteti
Dam at Samedupi (37
MCM/a)
KEY
Hydr
y oelectr
dr
ic
oelectr power plant
Storage
Stor
da
age
m
da
Run-of-rirver abstraction
Irrig
ri ation scheme
Return
e
flows
turn
Figure 3.1
Position of water-resource developments included in the water-use scenarios in
the upper portion of the catchment.
39
E-Flows Ecological and Social Predictions Scenario Report
Figure 3.2
Position of water-resource developments included in the water-use scenarios in
the lower portion of the catchment.
Details of the water-resource development included and the modeling thereof for inclusion in
the three scenarios are provided in Report 06/2009: Scenario Report: Hydrology.
3.2.
Hydrological data generated for the scenarios
The hydrological modelling for the three scenario yielded times series of daily flows for a 43-
year hydrological period (1959 - 2001) for the river sites (Sites 1-6) and a 20-year
hydrological period (1983 - 2002) for the Delta (Site 7) and Boteti (Site 8). For each
scenario, the level of water use outlined in Table 3.1 was imposed on the full hydrological
period.
It is important to emphasise that the base hydrological for the period used, 1959-2001, show
a declining trend in mean annual runoff (e.g., Figure 3.3). This trend was primarily driven by
climatic conditions, as was borne out by a reversal of the trend in 2004-2009. Unfortunately,
these more recent data were not available for the modelling exercise. They were, however,
made available for certain sites during the Knowledge Capture Workshop. This meant that
the biophysical specialists could calibrate their response curves using the more recent data.
For the hydrological modelling of the scenarios, however, `present-day' was represented by a
simulated record for 1959-2001.
Thus, for the river sites (Sites 1, 2, 3, 4, 5 and 6), the present-day situation is defined as a
43-year hydrological period (1959 - 2001) with 2008 levels of water use applied throughout.
40
E-Flows Ecological and Social Predictions Scenario Report
300
P resent D a y
PDSim
HighDEv
MedDev
LowDev
250
MEDIAN
) 200
M
C
M
f
(
150
unof
r
nnual
A 100
50
0
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
00
01
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
19
20
20
Figure 3.3
Annual runoff data for Site 4: Kapako (1959-2001).
For the delta (Site 7) and the Boteti River (Site 8), the present-day situation is defined as a
20-year hydrological period (1983 - 2002) with 2008 levels of water use applied throughout.
To facilitate comparison between the scenarios, each scenario comprises the same
hydrological period as the present-day scenario, with its water use levels applied throughout.
For instance, the high scenario at Site 4: Kapako, comprises the 1959-2003 period and
assumes that all of the upstream developments envisaged in the high scenario would be in
place for the entire time.
3.3.
The ecologically-relevant summary statistics for the river sites (Sites
1-6)
The time series of daily flows were analysed using set of hydrological rules to generate the
following ecologically-relevant summary statistics for each year of record:
1. Dry season onset in weeks
2. Dry season minimum 5-day discharge in m3s-1
3. Dry season duration in days
4. Flood season onset in weeks
5. Flood type (0-6)
6. Flood season duration in days.
Details on the division of the flow regime and the generation of ecologically-relevant
summary statistics are provided in Report 03/2009: Guidelines for data collection, analysis
and scenario creation and Report 06/2009:Scenario Report: Hydrology.
The annual statistics are stored in the DSS, and their median values for each scenario at
each site, with comments where relevant, are provided in Table 3.2 to Table 3.6. The
statistics for flood season peak 5-day magnitude and flood season volume are presented
separately in Table 3.2 to Table 3.6. These were later combined to provide Flood Type (0-6).
41
E-Flows Ecological and Social Predictions Scenario Report
Table 3.2
Median values for the ecologically-relevant summary statistics for each
scenario for Site 1: Capico. PD = simulated present day flow regime. L = low
scenario; M = medium scenario; and H = high scenario.
Flow category
PD
Low
Medium
High
Comment
All Scenarios similar and
MAR (McM)
22
14
14
13
lower than PD
All Scs similar and 11 wks
Dry season onset
Aug
May
May
May
earlier than PD
All Scs similar and approx 18
Dry season duration (days)
86
212
212
213
wks longer than PD (ie ends
later and starts earlier)
Dry season minimum flow
All Scs similar. Drastic drop
12 0.4 0.3
0.3
(m3s-1)
from PD
All Scs similar and delayed
Flood season onset
Dec
Jan
Jan
Jan
by about 7 weeks compared
to PD
All Scs similar and slightly
Flood season peak (m3s-1)
38 35 35
35 smaller than PD
Flood season volume (Mcm)
456
231
231
230
All Scs similar and half of PD
All Scs similar and approx 14
Flood season duration (days) 197
97
97
97
wks shorter than PD
Table 3.3
Median values for the ecologically-relevant summary statistics for each
scenario for Site 2: Mucundi. PD = simulated present day flow regime. L = low
scenario; M = medium scenario; and H = high scenario.
Flow category
PD
Low
Medium
High
Comment
Gradual decline to 93%,
MAR (McM)
166
155
140
128
85%, 77% of PD
All Scs similar. Onset 2-3
Dry season onset
July
July
July
July
weeks earlier than PD.
Progressive lengthening of
Dry season duration (days)
96
124
143
152
dry season by 4, 7 and 8
weeks
Min Q drops to 50% (L),
Dry season minimum flow
38% (M) of PD and then
32 16 12
24
(m3s-1)
under H increases to 75% -
dam releases in dry season
Progressively delayed by 2-
Flood season onset
Jan
Jan
Jan
Jan
3 weeks
Peak not affected until (H),
Flood season peak (m3s-1)
429 430 429
401 when drops to 93% of PD
Progressive loss of volume:
Flood season volume (Mcm)
3713
3558
3178
2531
96%, 86%, 68 of PD
Progressive shortening of
Flood season duration (days) 148
135
123
111
flood season by 2, 3, 5
weeks
42
E-Flows Ecological and Social Predictions Scenario Report
Table 3.4
Median values for the ecologically-relevant summary statistics for each
scenario for Site 3: Cuito Cuanavale. PD = simulated present day flow regime.
Flow category
PD
Low
Medium
High
Comment
MAR (McM)
119
119
119
119
Dry season onset
July
July
July
July
Much longer duration than
Dry season duration (days)
182
182
182
182
other Angolan sites
Dry season minimum flow
Much higher flow than other
80 80 80
80
(m3s-1)
Angolan sites
Flood season onset
Jan
Jan
Jan
Jan
Quite a small peak compared
Flood season peak (m3s-1)
163 163 163
163 to Mucundi
Flood season volume (Mcm)
1968
1968
1968
1968
About half of Mucundi
Within range of other
Flood season duration (days) 162
162
162
162
Angolan sites
Table 3.5
Median values for the ecologically-relevant summary statistics for each
scenario for Site 4: Kapako. PD = simulated present day flow regime. L = low
scenario; M = medium scenario; and H = high scenario.
Flow category
PD
Low
Medium
High
Comment
Progressive decline to 93%,
MAR (McM)
164
152
140
129
85%, 79% of PD
Dry season onset (wk)
July
July
July
July
Approx same throughout
Progressively longer: 2, 5, 6
Dry season duration (days)
135
150
168
176
weeks more than PD
Dry season minimum flow
Decline through L and M to
35 20 15
19 43% then increase for H to
(m3s-1)
54%
Slight delay by about 2 wks in
Flood season onset
Jan
Jan
Jan
Feb
H
Medium about same as PD; L
Flood season peak (m3s-1)
452 446 453
433 slightly lower at 99% and H at
96% of PD
Progressive decline to 96%,
Flood season volume (Mcm)
3694
3535
3209
2580
87%, 70% of PD
Progressively shorter flood
Flood season duration (days) 154
147
130
117
season: 1, 4, 6 weeks shorter
than PD
43
E-Flows Ecological and Social Predictions Scenario Report
Table 3.6
Median values for the ecologically-relevant summary statistics for each
scenario for Site 5: Popa Falls and Site 6: Panhandle. PD = simulated present
day flow regime. L = low scenario; M = medium scenario; and H = high
scenario.
Flow category
PD
Low
Medium
High
Comment
Progressive decline: 97%,
MAR (McM)
270
261
245
186
91%, 69% of PD
Progressively earlier: 1, 3,
Dry season onset
Aug
July
July
June
and 7 weeks earlier than PD
Progressively longer dry
Dry season duration (days)
115
130
145
193
season: 2, 4,11 weeks more
than PD
Dry season minimum flow
Progressive decline to very
114 101 93
21 large drop for H: 89%, 82%,
(m3s-1)
18% of PD
Slightly delayed by 1 wk (M)
Flood season onset
Jan
Jan
Jan
Feb
and 2 wks (H)
Progressive very slight
Flood season peak (m3s-1)
620 618 611
573 decline: 99%, 98, 92% of PD
Progressive decline: 96%,
Flood season volume (Mcm)
5269
4980
4450
3294
84%, 63% of PD
Progressive shortening of
Flood season duration (days) 150
143
129
103
flood season by 1, 3, 7 weeks
3.4. Summary
statistics
for Site 7: Xaxanaka
Hydrological data per se are not particularly useful in the analysis of the Okavango Delta, as
areas of inundation vary year on year with climate. Thus, while the overall proportion of
inundated area may be similar in years with similar flow characteristics, the location of the
inundated areas varies over time. For his reason, a semi-conceptual hydraulic model (Wolski
et al. 2006), which was calibrated using observed data for the period of 1968-2002, was used
to generate inundation patterns over the south-western portion of the Okavango delta, as
represented by Site 7: Xaxanaka. The output of the model is a series of vegetation
types/habitat based on duration and frequency of inundation (Table 3.7).
Table 3.7
Vegetation types used in the model
Abbreviation Description
CH-ps
Channels in permanent swamp
L-ps
Lagoons in permanent swamp
BS-ps
Backswamp in permanent swamp
SP-sf
Seasonal pools in seasonally flooded zone
Sed-sf
Seasonal sedgeland in seasonally flooded zone
Gr-sf
Seasonal grassland in seasonally flooded zone
S-sf
Savanna- dried floodplain in seasonally flooded areas
Mean percentage over for these vegetation types for simulated present-day inflows between
1983-2002 is shown in Table 3.8.
Table 3.8
Mean percentage of cover for vegetation types in the area of the Delta
represented by Site 7, for simulated present-day conditions, and for the low,
medium and high scenarios.
Inflows CH-ps
L-ps BS-ps
SP-sf Sed-sf
Gr-sf S-sf
44
E-Flows Ecological and Social Predictions Scenario Report
Mean percentage cover
Present-day
0.49 0.98 47.58 0.89 27.27 16.32 6.47
Low
0.46 0.92 44.62 0.94 27.84 18.08 7.13
Medium 0.43 0.867 41.67 0.98 26.28 21.51 8.29
High 0.11 0.23 11.02 1.18 28.59 29.12 29.74
Details of the model used are provided in Report 05/2009: Hydrology Report: Data and
models.
3.5. Summary
statistics
for Site 8: Boteti
The percentage of the 200-km study reach of the Boteti River that will be inundated (wet);
isolated pools (pool) and dry under the present-day, low, medium and high scenarios is
provided in Figure 3.4, Figure 3.5, Figure 3.6 and Figure 3.7, respectively.
Details of the model used to provide these data are provided in Report 05/2009: Hydrology
Report: Data and models.
100%
90%
h
80%
70%
r
eac
k
m
60%
Dry
200
50%
Pool
40%
Wet
c
entage of
30%
er
P
20%
10%
0%
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
Figure 3.4
Percentage of the 200-km study reach of the Boteti River that will be inundated
(wet); isolated pools (pool) and dry under the present-day simulated conditions
given climatic conditions that prevailed from 1973-2002.
45
E-Flows Ecological and Social Predictions Scenario Report
100%
90%
h
80%
70%
r
eac
k
m
60%
Dry
200
50%
Pool
40%
Wet
c
entage of
30%
er
P
20%
10%
0%
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
Figure 3.5
Percentage of the 200-km study reach of the Boteti River that will be inundated
(wet); isolated pools (pool) and dry under the low scenario given climatic
conditions that prevailed from 1973-2002.
100%
90%
h
80%
70%
r
eac
k
m
60%
Dry
200
50%
Pool
40%
Wet
c
entage of
30%
er
P
20%
10%
0%
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
Figure 3.6
Percentage of the 200-km study reach of the Boteti River that will be inundated
(wet); isolated pools (pool) and dry under the medium scenario given climatic
conditions that prevailed from 1973-2002.
46
E-Flows Ecological and Social Predictions Scenario Report
100%
90%
h
80%
70%
r
eac
k
m
60%
Dry
200
50%
Pool
40%
Wet
c
entage of
30%
er
P
20%
10%
0%
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
Figure 3.7
Percentage of the 200-km study reach of the Boteti River that will be inundated
(wet); isolated pools (pool) and dry under the high scenario given climatic
conditions that prevailed from 1973-2002.
3.6.
Process follow after the generation of ecological summary data
Once the summary ecological data are generated they are entered into the DSS. In the
DSS, the response curves are used to predict the biophysical and social outcomes for the
flow regime of interest. The DSS is described in more detail in Report 02/2009: Process
Report.
OUTPUTS
Ecologically
relevant
1.
time-series of abundance,
flow categories
area or concentration of
key indicators;
2.
estimated mean
percentage changes from
present day in the
abundance, area or
Biophysical Discipline
concentration of key
Response Curves
indicators
3.
estimated change in
discipline-specific
integrity, relative to
present day
Social Discipline
4.
estimated change in
Response Curves
overall ecological
integrity, relative to
present day
Figure 3.8
Summary of process within the DSS
47
E-Flows Ecological and Social Predictions Scenario Report
4.
Biophysical results: Disciplines
Note:
1.
The results presented here are unique to the configuration of development options, and
their operating rules, included in the water-use scenarios. Different configurations,
and/or different operating rules would yield different outcomes for the biophysical
environment.
2.
The results presented here exclude consideration of:impacts of developments other
than flow, e.g., changes in sediment supply;
· landuse
changes;
· climate
change.
3.
The only water use included in the scenarios for the Cuito River upstream of Site 3:
Cuito River at Cuito Cuanavale was a run-of-river hydropower plants that had no effect
on the flows at Site 3. Thus, none of the scenarios affected Site 3.
4.
The locations of the sites prohibit the prediction of likely impacts of any of the scenarios
on the lower Cuito River.
4.1. Introduction
The Chapter summarises the results for each of the biophysical indicators in terms of overall
changes in their area, concentration or abundance relative to the simulated present day
situation.
Additional details on the biophysical results for each scenario are provided in Report
07/2009: Scenario Report: Ecological and social predictions (VOLUME 2).
4.2. Geomorphology
4.2.1
Indicator 1: Extent - exposed rocky habitat
Summary of characteristics
This indicator considers the extent of exposed rocky habitat at a site during the low flow
season. It does not consider the other potential impacts, such as of sediment deposition
covering bedrock exposures, only the exposed bedrock above the water surface. Exposed
rocky areas provide valuable habitat for birds and wildlife. There is a direct relationship
between flow level and rocks exposed above water level. As water level rises, less rocky
area is exposed.
This indicator is used for Sites 1, 2 and 5.
Impact of the Water-use Scenarios
It is predicted that there will be a drastic increase in seasonal exposure of rocky habitat at
Capico (Site 1) because of loss of the dry-season flows (c. 200% increase) under the low,
medium and high scenarios. There will be similar increase at Site 2 under the low and
medium scenarios, but exposure will approximate present day levels under the high scenario,
48
E-Flows Ecological and Social Predictions Scenario Report
because of the lowflow season releases from the proposed dam included in the scenario.
Site 5 will also be seriously affected by the medium and high flow scenario, with 50% and
200% increases in lowflow season exposure, respectively.
4.2.2
Indicator 2: Extent coarse sediments
Not used in final analysis.
4.2.3
Indicator 3: Cross sectional area of channel
Summary of characteristics
The cross sectional area of the channel responds mainly to flood conditions. Floods larger
than the historical maximum should rapidly enlarge the cross sectional area, and a reduction
of floods should result in a narrowing of the flood channel (and a reduction in channel cross-
sectional area). However, the channel also responds to low flow conditions or extended low
flow conditions, which enables vegetation to encroach into the channel, trapping sediment,
ultimately reducing the channel cross section. This process is much slower than channel
enlargement, and intervening floods will offset this to a certain extent.
This indicator is used for Sites 1, 2, 3, 4, 5 and 6.
Impact of the Water-use Scenarios
It is predicted that there will be a drastic decrease(c. 70%) in cross-sectional area at Capico
(Site 1) under the low, medium and high scenarios. This type of drastic decrease as a result
of encroachment, coupled with a decline in flood magnitude and duration of floods is also
predicted for Sites 2 (40% reduction) and 6 (60% reduction) under the high scenario. For the
rest, there will be slight changes in cross-section areas, but these are unlikely to be
significant.
4.2.4
Indicator 4: Extent: backwaters
Summary of characteristics
Backwater provide valuable habitat for plants, fish, birds and wildlife. Filling or emptying of
backwaters is directly related to the water level in the river. Backwaters gradually fill with
sediment and therefore may be shallower than the main channel - in that case they may
empty before the river dries up. The backwaters tend to be steep sided, so the surface area
changes little as water depth changes.
This indicator is used for Sites 1, 3 and 4.
Impact of the Water-use Scenarios
It is predicted that the high level of abstraction at Site 1 under the low, medium and high
scenarios will considerably reduce flows in the rivers during the low flow season (hot season
in October-November) when the river is at its lowest, and there will be a drastic decrease (c.
60%) in backwaters. This is somewhat offset at Sites 2 and 4 by lowflow season releases.
49
E-Flows Ecological and Social Predictions Scenario Report
4.2.5
Indicator 5: Extent: vegetated islands
Summary of characteristics
Vegetated islands in the Mukwe-Andara-Popa Falls section of the Okavango River (and
upstream) are normally comprised of sand on bedrock. Grass, reeds, bush and trees
stabilise the sand by reducing wash away during above-average high flows and also
promoting deposition of more sand during overtopping of the island.
Reduced flows have little impact on vegetated islands as long as the plants there still get
enough water to survive and regenerate. Excessively high floods, however, are likely to
cause erosion of the margins of islands. In many cases this erosion is limited to the margins
because of the bedrock base to the island.
This indicator is used for Site 5.
Impact of the Water-use Scenarios
It is predicted that there will be no appreciable impact on vegetated islands under any of the
scenarios.
4.2.6
Indicator 6: Sandbars at lowflow
Summary of characteristics
Extensive exposed sand bars exist mainly below Popa Falls. Upriver, although much of the
river bed is sand, the sand bars are mostly submerged just below the surface during the low
flow season.
If only the effect of water flow on sandbanks is considered, then lower flow will expose a
greater extent of sandbanks. However, the real issue the fact that dams and weirs trap
sediment. Downstream of a weir or dam the river is deprived of sediment, so it erodes its
bed, banks and floodplains until it is once again carrying its maximum load. Thus, for some
distance downstream of a weir or dam the sandbanks will be removed. This is important at
Sites 2 and 5 were dams/weirs form part of the high scenario, but is not included in the
results for this indicator as sediment trapping by dams was not included in the DSS. If there
were, the impacts would likely be considerably higher than predicted here.
This indicator is used for Site 5.
Impact of the Water-use Scenarios
There will be little noticeable difference in the extent of exposed sandbars under the low or
medium scenarios. Under the high scenarios, however, lowflow season lowflows will be
considerably reduced, and seasonal exposure of sandbars will be considerably more (c.
250%) than under the present-day scenario.
4.2.7
Indicator 7: Percentage clays and silts on floodplain
Summary of characteristics
This refers to the silts and clays in the top 300 mm of the floodplain surface sediments.
Floodplains are made predominantly of fine sand, but there is a small amount of silt and clay-
sized particles, which is also deposited by the river. The silt and clay is significant for
agriculture because it helps to retain moisture and nutrients. Silt and clay tend to get lost due
50
E-Flows Ecological and Social Predictions Scenario Report
to downward mixing by soil organisms, trampling by livestock, and removal by wind, and are
replenished by flooding. Both loss and replenishment occur over fairly long time scales, c. 20
years or so, although sudden depositions do occur under large floods.
This indicator is used for Sites 3 and 4.
Impact of the Water-use Scenarios
None of the scenarios affect Site 3. At Site 4, there will be little or no effect on silts and clays
under the low and medium scenarios. Under the high scenario, however, it is predicted that
there will be a gradual reduction in the amount of slits and clays on the floodplain
corresponding to a reduction in the frequency and duration of over-bank flooding.
4.2.8
Indicator 8: Extent: inundated floodplain
Summary of characteristics
This indicator considers the extent of inundation of the floodplains at Sites 3, 4 and 6.
Inundation of the floodplain is strongly linked to the peak and duration of the flood season
flows, i.e., their volume (Figure 4.1). Reduced volume of flow in the flood season will result in
less over-bank flooding. This results in smaller areas of the floodplain being inundated.
50
45
40
35
30
25
20
15
area flooded (km2) 10
5
0
0
1000
2000
3000
4000
5000
6000
7000
8000
volume (mcm)
Figure 4.1
Relationship between flood season volume and area of floodplain inundated for
Site 4: Kapako.
This indicator is used for Sites 3, 4 and 6.
Impact of the Water-use Scenarios
None of the scenarios affect Site 3. Under the low scenario, no significant effects are
predicted for either Site 4 or 6. Under the medium scenario, there will be a slight reduction in
the extent of inundation of the floodplain at Site 6 and a clear reduction in c. 20% of the years
at Site 4. This represents a considerable increase in the periods between inundation events
for some components of the floodplain. Under the high scenario there is reduced flooding in
c. 30% of the years, and a doubling of the years where the floods `fail' completely. This will,
of course, have knock-on effects for the biota and people using the floodplain resources.
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4.2.9
Indicator 9: Extent: pools and pans
Summary of characteristics
This indicator considers the extent of perennial pools and pans on the floodplains at Sites 3,
4 and 6. These are partly dependent on refilling from overbank flooding and rain, but are
sustained through the lowflow season by the high water table on the floodplains. As the river
level drops, so the water table in the floodplain will also drop. If the bed of a pool no longer
intersects the water table, the pool will dry out, although seepage from the non-saturated
zone may also contribute to pool water.
This indicator is used for Sites 3, 4 and 6.
Impact of the Water-use Scenarios
None of the scenarios affect Site 3. At Site 4 all the scenarios will result in a reduction (20-
30%) in perennial pools and pans on the floodplain, but this will be highest for the medium
scenario (c. 30% reduction). This is because the abstraction during lowflow season will be
offset slightly by releases in the high scenario. The pattern is a little different at Site 6, where
there is more of a ponding effect of low season flows. At Site 6, the low and medium
scenarios are not predicted to have an appreciable effect, but the high scenario will result in
a c. 10% reduction.
4.2.10
Indicator 9: Extent: cut banks
Summary of characteristics
Cut banks are a natural phenomenon in the Okavango, particularly in the middle reaches
through Namibia. Higher flow velocities during flooding erode banks, building meanders and
creating cutoffs. This process is enhanced if water levels drop rapidly, as hydrostatic
pressure of water in the sandy bank material tends to result in bank collapse. A decline in
bank cutting will result in a gradual stabilization of the channel and a loss of habitat.
This indicator is used for Sites 3, 4 and 6.
Impact of the Water-use Scenarios
None of the scenarios affect Site 3. There will be no appreciable effect at the other sites for
the low and medium scenarios. Although some decrease in bank cutting is expected under
the high scenario, this is unlikely to be significant. The inference is that overall channel
pattern, e.g., straight, meandering or braided, should not be affected. This is mainly
because, although there will be a reduction in the magnitude and duration of flooding events,
many of these will still occur under all of the scenarios analyses. However, if sediment
supply were to be curtailed for any reason, there would probably be a marked increase in
bank erosion, and a concomitant change in channel pattern.
4.2.11
Indicator 10: Carbon storage
Summary of characteristics
Wetlands affect the levels of atmospheric carbon in two ways: First, many wetlands,
particularly boreal and tropical peatlands, are carbon reservoirs. Carbon is contained in the
standing crops of trees and other vegetation and in litter, peats, organic soils and sediments
that have been built up, in some instances, over thousands of years. These carbon
reservoirs may supply large amounts of carbon to the atmosphere if water levels are lowered
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E-Flows Ecological and Social Predictions Scenario Report
or land management practices result in oxidation of soils. Second, many wetlands also
continue to sequester carbon from the atmosphere through photosynthesis by wetland
plants; many also act as sediment traps for carbon-rich sediments from watershed sources.
However, wetlands also simultaneously release carbon as carbon dioxide, dissolved carbon,
and methane. The net carbon sequestering versus carbon release roles of wetlands are
complex and change over time although net, gradual sequestration occurs over time for
peatland wetlands such as the Okavango Swamp1.
This indicator considers the net peat/carbon storage in the swamps.
This indicator is used for Site 7.
Impact of the Water-use Scenarios
It is predicted that there will be a c. 70% reduction in carbon storage in the area represented
by Site 7 under the high scenario. Carbon storage is also predicted to decline under the low
and medium scenarios but this is unlikely to be significant.
4.2.12
Summary of geomorphological response to scenarios
Increasing off-stream water use in the Okavanago catchment is likely to result in a trend
towards stabilisation and narrowing of the main channels, possibly accompanied by a
deepening of the channel and a terrestrialisation of the vast floodplains.
In general, however, exclusion of consideration of changes in sediment supply liked with
water-resources developments and/or landuse changes means that the predictions for the
geomorphology are incomplete, and quite possibly the changes are seriously
underestimated.
4.3. Water
Quality
4.3.1
Indicator 1: pH
Summary of characteristics
Values are those for the main channel. Generally, pH increases with decreasing flow.
This indicator is used for all eight sites.
Impact of the Water-use Scenarios
Under Present Day conditions, values mostly range within 70% and 115% of the median.
Values are predicted to increase very slightly, without the range necessarily extending, under
the Low and Medium Scenarios, but show a significant increase under the High Scenario at
Sites 4, 6, 7 and 8 to up to 46% higher than Present Day median and with very few values
below the median. This is probably because as dry-season flows fall progressively lower
there will be higher concentrations of carbonates and bicarbonates.
1 www.usgcrp.gov/usgcrp/Library/nationalassessment/newsletter/1999.08
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4.3.2
Indicator 2: Conductivity
Summary of characteristics
Values are those for the main channel. Generally, conductivity increases with decreasing
flow.
This indicator is used for all eight sites.
Impact of the Water-use Scenarios
Modelled Present Day values range between 34% and 268% of the Present Day median,
increasing in drier years of lower flow. Most scenario predictions remain within that range,
but it is worth noting that there is tendency for the range to progressively shift upwards
through the scenario, with Site 4 (Kapako) showing values higher than the PD range up to
307% under the High Scenario.
4.3.3
Indicator 3: Temperature
Summary of characteristics
Diel temperature ranges are addressed. These are expected to increase with development
that reduces river flow.
This indicator is used for all eight sites.
Impact of the Water-use Scenarios
Diel temperature ranges in the river under Present Day are 48-58% of median in the wet
season, and a slightly greater range of 80-98% in the delta and Boteti. The ranges in the dry
season, when flows are lower and ambient temperatures have more influence, are 153-230%
along the river, and up to 343% in the Boteti due to its tendency to dry out.
Diel ranges mostly stay within these ranges in the scenarios, but the High Scenario pushes
the diel range permanently into the higher end of the range that is - higher than the present
median - at Sites 5, 6 and 7, and maintains a greater range for longer in the Boteti.
4.3.4
Indicator 4: Turbidity
Summary of characteristics
Turbidity decreases with decreasing flow at Sites 1 and 2. Values increase with high flows in
the flood season, as sediments are lifted into suspension.
This indicator is used for all eight sites.
Impact of the Water-use Scenarios
No significant changes are expected for the Low and Medium Scenario at all sites. Median
turbidity levels are predicted to increase for Sites 6-8 under the High Scenario.
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4.3.5
Indicator 5: Dissolved oxygen
Summary of characteristics
Decrease in flow results in an increase in Dissolved Oxygen at sites 1 - 6. At sites 7 and 8
the concentrations decrease with a decrease in flow.
Impact of the Water-use Scenarios
Sites 1 to 6 show progressively increased median DO concentrations through the scenarios,
whilst median concentrations decrease at Sites 7 and 8.
4.3.6
Indicators 6, 7 and 8: Total nitrogen, total phosphorus and chlorophyll a
Summary of characteristics
Concentrations increase with decreasing flow at all the sites, but the relationship is slightly
weaker for phosphorus.
This indicator is used for all eight sites.
Impact of the Water-use Scenarios
Concentrations are predicted to increase progressively through the scenarios as flow
volumes decrease, with Sites 1, 5, 6 and 7 showing more than doubling of the Present Day
medians.
4.3.7
Summary of water-quality responses to scenarios
The water quality of the Okavango system is good, and values of all indicators are predicted
to remain mostly within the natural variability through the Low and Medium Scenario. Most
indicators are predicted to noticeably move away from Present Day values with the High
Scenario, particularly in the lower basin, from Site 4 downstream.
It should be noted that not all chemical variables are addressed in this exercise, and that for
those included only the direct changes as a result of flow changes are described. Water-use
developments, as represented by the three scenarios, will likely cause additional water-
quality changes, brought about by increased effluents from urban areas, agricultural return
flows carrying pesticides and fertilisers, and changed DO and temperature levels caused by
storage dams.
4.4. Vegetation
4.4.1
Indicator 1: Channel macrophytes (submerged)
Representative species: Potamogeton spp. (pondweed), Vallisneria aethiopica (no common
name) and Lagarosiphon ilicifolius (oxygen weed).
Summary of characteristics
These are species that grow along the edges of main channel or in side channels. All or part
of vegetation is permanently submerged, and the plants are either rooted or floating. They
need permanent, flowing, clear water. Their cover increases or decreases depending on
water volume in lowflow season and could decline to zero if the channel dries out. Sudden or
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E-Flows Ecological and Social Predictions Scenario Report
very large floods could also reduce cover. Poor water quality or low light penetration will also
negatively affected them.
These plants are used as indicators for Sites 1, 2, 3, 4, 5 and 6.
Impact of the Water-use Scenarios
It is predicted that there will be a drastic decrease (c. 90%) in the cover of submerged
macrophytes in the channel at Capico (Site 1) under the low, medium and high scenarios.
This is in direct response to the abstraction of 95% of the water in the lowflow season that
will, at times, dry the river out completely. At Site 2 and 4, there will be a sharp decline in
channel macrophytes under the medium scenario (c. 80% at Site 2), but only a slight decline
under the low and high scenarios. This is mainly because the lowflow releases offset some
of the other impacts under the high scenario. At Sites 5 and 6, the situation is somewhat
different, with slight declines under the low and medium scenarios but a nearly total decline
(c. 80-90%) under the high scenario. This is mainly in response to the reductions in flows
during the lowflow season.
4.4.2
Indicator 2: Lower wet bank
Representative species: Vossia cuspidata, Cyperus papyrus.
Summary of characteristics
These are species that grow along the permanently wet inner margin in main channel. They
are either floating plants with stems forming dense mat, with leaves and flowers above water
or rooted in the sand/peat. They prefer flowing water to standing water.
Vossia cuspidata is a robust, perennial grass with spongy, floating, creeping stems,
associated with deep, permanent water. It is rooted in the channel bed, but the extremely
long, floating stems can trail out into the current. Cyperus papyrus is a large, perennial
sedge with stout creeping stems and erect stems in permanent swamps and on the margins
of large rivers.
Papyrus and hippo grass respond slightly differently to flow but as a general rule they do not
occur at the same site (or at least they dominate at different sites). Hippo grass will survive
as long at there is water to cover its roots, and its leaves will float higher or lower as water
level rises or falls. It can tolerate more desiccation than can papyrus.
These plants are used as indicators for Sites 4, 5 and 6.
Impact of the Water-use Scenarios
There is no impact expected for any of the scenarios at Site 4. At Sites 5 and 6, however,
the predicted impacts are expected to be gradually more severe under the low, medium and
high scenarios, respectively. Under the high scenario, the lower wetbank will be severely
reduced (c. 20% of present), mainly as a result of the severe reductions in flows during the
lowflow season, when the wetter channel will shrink significantly leaving the wetbank
vegetation stranded, and dry. While it is expected that the vegetation may be able to
withstand occasional drying out it is unlikely to be able to cope with the long periods without
water that will characterise the lowflow season under the high scenario.
4.4.3
Indicator 3: Upper wetbank 1 (reeds)
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Representative species: Phragmites australis.
Summary of characteristics
Phragmites grows on the outer edges of the main channel. It is typically emergent vegetation
with its roots wet, but can withstand being out of water provided the soils are water logged. It
reproduces vegetatively by means of stolons (underground horizontal stems) and rapidly
colonises new areas, extending into areas that are further away from water and often
becoming the dominant plants. It does not need flowing water but it does best where there is
at least some soil moisture. With a lowering of the volume and duration of flooding it is likely
to expand into areas occupied by the indicators on either side of it.
These plants are used as indicators for Sites 1, 2, 3, 4, 5 and 6.
Impact of the Water-use Scenarios
A c. 50% decrease is predicted for the cover of reeds at Capico (Site 1) under the low,
medium and high scenarios. This is a result of two main impacts. Firstly the loss of lowflow
season flows, which will strand the reeds on the outer margins of the channel, and secondly,
the continued presence of the large floods, which will prevent the reeds from migrating closer
to the new lowflow water's edge. Further to that, no major impacts are expected under either
the low or medium scenarios for any of the sites. Under the high scenario, however, there
are slight decreases (20%) expected at Site 5 and 6.
4.4.4
Indicator 4: Upper wetbank 2 (trees/shrubs)
Representative species: Searsia (Rhus) quartiniana, Ziziphus mucronata.
Summary of characteristics
Searsia (Rhus) quartiniana is a dense shrub or tree with a wide range of ecological
tolerances within the context of perennial rivers. It is found along the banks and floodplains
of perennial rivers, on islands in permanent swamps, as well as occasionally in ephemeral
watercourses. Ziziphus mucronata is found in a variety of different habitats; very often close
to water, but can also be found far from water.
These plants are used as indicators for Sites 1, 2, 4 and 5.
Impact of the Water-use Scenarios
A gradual decrease is predicted for the cover of trees and shrubs at Capico (Site 1) under the
low, medium and high scenarios (c. 40% loss over 43 years). Under the medium scenario
Sites 2 and 4 will be most impacted, with 30-50% reductions expected (higher if sediment
supply is curtailed). No major changes are expected in trees and shrubs at Site 5 under the
medium scenario, but there a c. 80% decline is predicted for the high scenario. Declines will
be gradual over time, with partial recovery in good flood years.
4.4.5
Indicator 5: River dry bank
Representative species: Combretum imberbe, Acacia tortilis, Albizia versicolor, Ficus
sycomorus, Garcinia livingstonei and Diospyros mespiliformis2.
2 Different species occur at different sites.
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Summary of characteristics
This group of species comprises large trees and dense shrubs that grow on the outer
margins of river banks. They are important for stabilising the river bank, and filter runoff from
the adjacent catchment. They grow near water but generally not in the water, although some
can withstand short periods of inundation. These trees and shrubs get their water via
groundwater seepage from the river.
These plants are used as indicators for Sites 1, 2, 3, 5 and 6.
Impact of the Water-use Scenarios
A gradual decrease is predicted for the cover of trees and shrubs at Capico (Site 1) under the
low, medium and high scenarios (c. 40% loss over 43 years). At the other sites, the low or
medium scenarios are not expected to significantly affect dry bank vegetation. The high
scenario may, however, result in a slight decline in dry bank vegetation at Sites 5 and 6.
4.4.6
Indicator 6: Floodplain dry bank
Representative species: Combretum imberbe, Acacia tortilis, Albizia versicolor, Ficus
sycomorus, Garcinia livingstonei and Diospyros mespiliformis.
Summary of characteristics
This group comprises the same species are Indicator 5: River dry bank. The difference
between them lies in the fact that this groups grows on the outer margin of the floodplain,
which means that they are more dependent on periodic inundation of the floodplain than are
their riverbank counterparts.
These plants are used as indicators for Sites 3, 4 and 6.
Impact of the Water-use Scenarios
There will be no significant impacts on the floodplain dry bank vegetation for the low and
medium scenarios, and only a slight negative impact (c. 10% over 43 years) for the high
scenario.
4.4.7
Indicator 7: River floodplain residual pools
Representative species: Nymphaea nouchali var. caerulea
Summary of characteristics
The plants of this community are all dependent on standing or slow-flowing, permanent
water, which is linked to and recharged by the main river. This is a seasonal effect as rain
will fill the pools during the rainy season and flood-waters will fill them during the flood
season.
These plants are used as indicators for Sites 3, 4 and 6.
Impact of the Water-use Scenarios
The persistence of perennial pools on the floodplain is closely linked to water levels in the
channel during the lowflow season as these support the water table on the floodplain, and
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E-Flows Ecological and Social Predictions Scenario Report
thus the water level in the pools. Since all of the scenarios involve some abstraction during
the lowflow period, they all have some impact on the persistence of pools on the floodplain
during the dry season. The predicted impact increases gradually from low (>90% of present),
to medium (> 80% or present) to high (20-60% of present).
4.4.8
Indicator 8: River lower floodplain
Representative species: Miscanthus junceus, Persicaria spp., Ludwigia spp.
Summary of characteristics
These plants are found in the deeper depressions on the floodplains, which receive water
from the river at high flow and presumably retain water for long periods, based on the water-
loving species that are found in them. The group comprises a mixture of species that prefer
permanent water or grow on dry land but close to water (Persicaria, Ludwigia). They are all
tolerant of total inundation for long periods and desiccation for varying periods. Their leaves
float on the surface of the water, while the flowers are held above the water.
Miscanthus junceus (swamp savanna grass/pampas grass) is an important floodplain
thatching grass in Namibia (Barnes, in litt. 2009).
These plants are used as indicators for Sites 3, 4 and 6.
Impact of the Water-use Scenarios
The lower floodplain vegetation is highly dependent on seasonal inundation. Consequently
there is a steady decline in this indicator at Sites 4 and 6 in response to a progressive
reduction in the magnitude and duration of flood flows from present day to the low, medium
and high scenarios. While the predicted loss is moderate for the low and medium scenarios
(<10%), it is high for the high scenario (80% at Site 6). Of more concern, however is that it
drier climatic conditions prevail for an extended period of time, e.g., during a drought, these
species will be almost completely lost from the system.
4.4.9
Indicator 9: River middle floodplain
Representative species: Setaria, Panicum, Vetiveria nigritana3, thatching grasses.
Summary of characteristics
Plants in this group are able to grow in areas away from water, but thrive in seasonally wet
areas. They are found predominately on the middle floodplain, on either clay or sand. There
tend to be large areas dominated by thatching and grazing grasses. An increase in the
length of inundation may be detrimental, but they would probably survive longer dry periods.
These plants are used as indicators for Sites 3, 4 and 6.
Impact of the Water-use Scenarios
At Site 4, the middle floodplain vegetation is expected to increase in area gradually from low
(c. 124% of present), to medium (c. 126% of present) to high (c. 130% of present). This is
because the slightly reduced flooding will enable these species to encroach on parts of the
floodplain that were previously too wet for them to survive. At Site 6, although there is a very
3 Angolan sites and the Panhandle.
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slight trend towards increasing middle floodplain vegetation, this is negligible for all the
scenarios.
4.4.10
Indicator 10: River upper floodplain (islands)
Representative species: Searsia (Rhus) with Acacia hebeclada, Acacia sieberiana,
Diospyros lycioides, grasses.
Summary of characteristics
These are the highest points on the floodplain itself and are seldom inundated. Long
inundation is detrimental to these plants. They are, however, dependent on some inundation
to recharge ground water, and for nutrients. The plant community is comprised of grasses,
shrubs, a few trees, and is equivalent to the wildlife discipline's secondary floodplain.
These plants are used as indicators for Sites 2 and 4.
Impact of the Water-use Scenarios
There will be no significant impacts on the upper floodplain island vegetation for the low and
medium scenarios, and only a slight negative impact for the high scenario.
4.4.11
Delta (Site 7) Indicators
The indicators used for Site 7: Okavango Delta at Xaxanaka are:
5. Open
water
6. Permanent
swamps
7. Lower
floodplain
8. Upper
floodplain
9. Occasionally-flooded
grassland
1. Sporobolus islands (These are small islands that form on termitaria in the seasonal
grasslands).
2. Riparian woodland, trees
3. Savanna, scrub.
These represent a gradient of wetness from open water through to savanna. Under natural
conditions proportion of these vegetation types fluctuates with climatic variation. Essentially,
under wet conditions there will be a predominance of open water, permanent swamp and
lower floodplains. If conditions dry out, the relative extent of upper floodplain and
occasionally-flooded grasses will increase. If conditions were to dry out even further, there
would be a gradual terrestrialisation of the delta and large portions thereof would revert to
savanna, with small Sporobolus islands on termitaria.
Impact of the Water-use Scenarios
The relative proportions of the vegetation indicators in the study area under present day, low,
medium and high scenarios are shown in Figure 4.2 to Figure 4.5, respectively.
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100%
80%
60%
40%
20%
0%
1
983
1
984
1
985
1
986
1
987
1
988
1
989
1
990
1
991
1
992
1
993
1
994
1
995
1
996
1
997
1
998
1
999
2
000
2
001
2
002
Open w ater
Permanent sw amp
Low er floodplain
Upper floodplain
Occassionally-flooded grasslands
Savanna
Figure 4.2
Proportions of the vegetation indicators in the study area over a 20-year period
under present-day conditions.
100%
80%
60%
40%
20%
0% 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Open w ater
Permanent sw amp
Low er floodplain
Upper floodplain
Occassionally-flooded grasslands
Savanna
Figure 4.3
Proportions of the vegetation indicators in the study area over a 20-year period
under the low scenario.
100%
80%
60%
40%
20%
0% 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Open w ater
Permanent sw amp
Low er floodplain
Upper floodplain
Occassionally-flooded grasslands
Savanna
Figure 4.4
Proportions of the vegetation indicators in the study area over a 20-year period
under the medium scenario.
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100%
80%
60%
40%
20%
0% 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Open w ater
Permanent sw amp
Low er floodplain
Upper floodplain
Occassionally-flooded grasslands
Savanna
Figure 4.5
Proportions of the vegetation indicators in the study area over a 20-year period
under the medium scenario.
Although some slight effects will be evident in the delta under the low and medium scenarios,
these are predicted to be negligible. Under the high scenario, however, it is predicted that
there will be a general drying out of the delta at Xaxanaka, a loss of open water and
permanent swamp and terrestrialisation of large portions of the area, relative to present day.
It is predicted that the area covered by savanna and scrub will be 3.5 times greater under the
high scenario than under present day.
4.4.12
Boteti (Site 8) Indicators
The indicators used for Site 8: Boteti River are:
1. Open water
2. Riparian woodland, trees.
Open water species occur in the Boteti River when the river course is inundated, when there
are isolated pools. The riparian woodland species on the other hand tend to persist for some
time (possibly as long as 50 years) even when the river is dry, as they are able to access
groundwater. Prolonged periods of no flow would, however, result in a gradual decline in
these species.
The relative extent of inundation, isolated pools and dry river bed in the Boteti River varies
with climatic variations. Under present day conditions, in wet periods as much as 100% of
the channel can become inundated and remain that way for several years. In dry periods
however, surface water in the Boteti River can dry up for extended periods, although people
are still able to access water by sinking wells into the river bed.
Impact of the Water-use Scenarios
The open water species are predicted to decline by c. 20% under the low scenario and c.
30% under the medium scenario. Under the high scenario, however, they will decline by as
much a 70% in direct response to a reduction in the number of years when there is water in
the system. During drier periods they will be absent from the system.
Riparian woodlands are predicted to show little change under the low and medium scenarios.
Under the high scenario, however, there will be a c. 20% decline in the cover of woodlands
species as a result of extended periods on no-flow.
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4.4.13
Summary of vegetation responses to scenarios
The riparian vegetation can loosely be divided into in-channel vegetation, floodplain-pool
vegetation, marginal vegetation, floodplain grasses and riparian trees and shrubs. In
general, the in-channel vegetation, floodplain-pool vegetation and marginal vegetation are
more dependent on lowflows and the floodplain grasses, and riparian trees and shrubs on
flood flows. Consequently, in-channel vegetation, floodplain-pool vegetation and marginal
vegetation are most negatively affected at Sites 1, 2, 5, 6 and 8, where abstraction will
seriously reduce low flows, particularly in the dry season. Riparian trees and shrubs are
slightly negatively affected, particularly under the high scenario, possibly because there is a
long lag time to their response. Of course, this also means that once impacted, they will take
even longer to recover, if they recover at all. In some cases, floodplain grasses are expected
to increase in line with a general terrestrialisation of the systems.
4.5. Aquatic
macroinvertebrates
4.5.1
Indicator 1: Invertebrates in channel submerged vegetation
Representative species: Crustacea (Freshwater shrimps).
Summary of characteristics
Water must always be present. At minimum flow habitat will be greatly reduced leading to
population decline as predation increases.
These invertebrates are used as indicators for Site 6.
Impact of the Water-use Scenarios
Abundances are predicted to decline slightly over the scenarios, with the only significant
impact being a permanent drop to about half Present Day levels under the high scenario.
4.5.2
Indicator 2: Invertebrates in channel marginal vegetation
Representative species: Crustacea (Freshwater shrimps).
Summary of characteristics
Water must always be present. High, long-duration flooding may lead to destruction of
habitat and reduction in abundance. Long duration of minimum flows restricted to the river
bed may also lead to loss of habitat.
These invertebrates are used as indicators for Sites 1, 2, 3, 4, 5, 6 and 8.
Impact of the Water-use Scenarios
Severe decline at Site 1 under all scenarios due to river flow almost failing in the dry season.
Very little noticeable impact elsewhere, although populations will shrink slightly as habitat
declines, most noticeably at Sites 5 and 8 under the high scenario.
4.5.3
Indicator 3: Invertebrates in channel fine sediments
Representative species: Unionidae, Sphaeridae.
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Summary of characteristics
This group of invertebrates lives under the sediments of the river bed. They will normally
survive as long as there is some water covering the sediment. Long dry spells will reduce
abundance or even eliminate these indicators.
These invertebrates are used as indicators for Sites 1, 4, 5 and 6.
Impact of the Water-use Scenarios
Little if any change predicted for the Low and Medium Scenarios, except at Site 1 where the
group is predicted to decline to about half Present Day abundances under all scenarios. A
similar level of decline is predicted for Sites 5 and 6 under the high scenario.
4.5.4
Indicator 4: Invertebrates of channel cobbles and boulders
Representative species: Hydropsychidae, Ecnomidae.
Summary of characteristics
This group of indicators lives among the cobbles and boulders of rocky river beds. They will
decline in abundance and may disappear if exposed to long duration of low flows that expose
the rocks.
These invertebrates are used as indicators for Sites 2, 5 and 8.
Impact of the Water-use Scenarios
Little if any impact until the high scenario, when abundances are predicted to drop to about
80% at Site 5 and 25% at Site 8.
4.5.5
Indicator 5: Invertebrates of fast-flowing channels
Representative species: Simuliidae, Hydropsychidae.
Summary of characteristics
These species inhabit fast-flowing sections of channels, where they depend on the flow of
water to provide food in suspension, which they collect from the current. They must live in
water throughout their lives. They will reduce in abundance and may disappear if flow slows
and water levels drop to expose the river bed.
These invertebrates are used as indicators for Sites 2,5 and 7
Impact of the Water-use Scenarios
Very little impact is anticipated under the Low and Medium Scenarios, although small drops
in abundance would follow any drying out and loss of wetted habitat. The High Scenario is
anticipated to cause a sever decline in abundances at Sites 5 and 7, to below 25% and 4%
respectively.
4.5.6
Indicator 6: Invertebrates in channel bedrock pools
Representative species: Dytiscidae.
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Summary of characteristics
The representative species is dytiscid diving beetles that inhabit pools in bedrock. High,
long-duration flooding will destroy this habitat through constant scouring flows while long
durations of low flows may result in the pools drying out and all habitat being lost.
These invertebrates are used as indicators for Site 2.
Impact of the Water-use Scenarios
No impact of any scenarios is anticipated.
4.5.7
Indicator 7: Invertebrates of floodplain marginal vegetation
Representative species: Coenagrionidae, Physidae, Planorbidae.
Summary of characteristics
The species inhabit vegetation growing at the sides of wet channels. They need water at all
times. Drying out of floodplains consequent to prolonged low flows will reduce or eradicate
their habitat and their abundances will decline accordingly.
These invertebrates are used as indicators for Sites 3 and 4.
Impact of the Water-use Scenarios
The Low and Medium Scenarios are anticipated to show no impact. An approximate 50%
decline in abundance is predicted for Site 4 under the High Scenario.
4.5.8
Indicator 8: Invertebrates of seasonal floodplain pools and backwaters
Representative species: Dytiscidae
Summary of characteristics
These species inhabit backwaters and temporary pools in seasonal floodplains. Drying out
of these areas will eradicate their habitat.
These invertebrates are used as indicators for Sites 4, 6 and 7.
Impact of the Water-use Scenarios
The Low and Medium Scenarios are anticipated to show little, if any, impact. The High
Scenario would cause drastic declines in abundance at Sites 6 and 7 to lower than 20% of
Present Day medians as these areas would receive less floodwaters less often.
4.5.9
Indicator 9: Invertebrates of mopane woodland pools
Representative species: Lyncedae, Daphnidae, Gammarus sp.
Summary of characteristics
Pools in mopane woodlands are rain-fed and so not dependent on flow regimes. Areas of
mopane woodland will expand where seasonal floodplains receive less flooding.
These invertebrates are used as indicators for Site 7.
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Impact of the Water-use Scenarios
The Low and Medium Scenarios are anticipated to show a mild increase in abundance as
floods decline and mopane woodland expands. The High Scenario is expected to cause a
noticeable increase in mopane woodlands, their pools and thus their aquatic invertebrates,
perhaps to 4 or 5-fold their Present day median abundances.
4.5.10
Summary of aquatic invertebrate responses to scenarios
With the exception of Site 1, the Low and Medium Scenarios are expected to have a low to
negligible impact on all indicators. The High Scenario is predicted to cause significant
declines in some indicators, mostly at Sites 5, 6, 7 and 8, whilst indicator 9 will increase
several fold at Site 7 as mopane woodlands expand.
4.6. Fish
4.6.1
Indicator 1: Fish resident in river
Representative species: Tigerfish [Hydrocynus vittatus]
Summary of characteristics
This fish guild spends most of its time in the main channel, undertaking longitudinal
migrations along the river system. They require deep, clear, running water and pools
throughout the year. They respond readily to seasonal and annual flow variability, increasing
in abundance up to double their median numbers in wet years/cycles and decreasing in
abundance to possibly half their median numbers in dry years/cycles. Natural variability in
abundance is greater in the upper basin and less from Site 5 (Popa) downstream probably
due to a less flashy hydrograph. Numbers can decline to zero in the Site 8 (Boteti) as this
ephemeral river periodically dries out. Changes in the natural flow pattern, increased
turbidity and deteriorating water quality will affect this guild of fish negatively.
These fish are used as indicators for Sites 1, 2, 3, 4, 5, 6, 7 and 8.
Impact of the Water-use Scenarios
It is predicted that there will be a drastic decline to very low numbers at Capico (Site 1)
because of loss of the dry-season flows. In the rest of the system, the low and medium
scenarios would result in a mild shift toward fewer years with high abundances and more with
low abundances. This trend would be accentuated in the high scenario where in the lower
part of the river system, at Site 2 and from Site 5 downstream, there would be no good years
and abundances would be permanently suppressed to half or less of their present levels with
little or no recovery in wetter years. This guild of fish would probably disappear from the
Boteti (Site 8).
4.6.2
Indicator 2: Migratory floodplain dependent fish: small species
Representative species: Bulldog [Marcusenius macrolepidotus]
Summary of characteristics
These are small-bodied fish species that are dependent on lateral migration to floodplains for
breeding and feeding. They are resident in the river through the lowflow season and migrate
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into floodplains during the flood season for feeding, breeding and protection against
predation. As a result they depend on regular flooding of shallow vegetated floodplains in the
flood season. They are also reliant on deeper [>50 cm] refuges during low flow conditions.
Major disruptions of the flooding patterns or sedimentation regimes will have a detrimental
effect on this species. However, minor changes that fall within the natural variability will not
have a major effect on these species.
These small, relatively short-lived fish can respond quickly, and increase to large numbers,
under good flooding conditions. As such their numbers are highly variable even under
present day (350-50%, and possibly even higher) as they track climatic variations in the
system.
These fish are used as indicators for Sites 1, 2, 3, 4, 5, 6 and 7.
Impact of the Water-use Scenarios
It is predicted that these fishes will be severely reduced or absent from the Capico River
under low, medium and high scenarios. For the rest of the catchment, they will only be
affected slightly by the low and medium scenario in the lowflow season, e.g., 180-20% at
Mucundi (Site 2). There will still be a fair amount of variability in their numbers but with more
of an emphasis on lower numbers than in the present day, i.e., slight loss of really good
breeding years. Under the low and medium scenarios the sites most affected will be Sites 2
and 8. Under the high scenario there will be very few good breeding years at any of the
sites. Sites 5, 6, 7 and 8 will be worst affected with few or no years where numbers will
exceed 100% of present day medians, and some years down to 0%. Median numbers for
Sites 7 and 8 will be lower than 25% of present day, and for Sites 5 and 6 they will be c. 50%
of present.
4.6.3
Indicator 3: Migratory floodplain dependent fish: large species
Representative species: Redbreast tilapia [Tilapia rendalli]
Summary of characteristics
These are large-bodied fish species that are dependent on lateral migration to floodplains for
breeding and feeding. They are resident in the river through the lowflow season and migrate
into floodplains during the flood season for feeding, breeding and protection against
predation. As a result they depend on regular flooding of shallow vegetated floodplains in the
flood season. They are also reliant on deeper [>200 cm] refuges during low flow conditions.
Major disruptions of the flooding patterns or sedimentation regimes will have a detrimental
effect on this species. However, minor changes that fall within the natural variability will not
have any major effect on these species.
These large, relatively long-lived fish can respond quickly, and increase numbers, under
good flooding conditions, but their numbers tend to be less variable year-on-year than those
of the small-bodies counterparts (Indicator 2).
These fish are used as indicators for Sites 1, 2, 3, 4, 5, 6 and 7.
Impact of the Water-use Scenarios
It is predicted that these fishes will severely reduced or absent from the Capico River (Site 1)
under low, medium and high scenarios. At Sites 2 and 4, the nett effect of high scenario will
be similar to that of the medium scenario because the loss in flooding will be offset by
releases in the lowflow season. Under the medium scenario at the rest of the sites, however,
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there will be a noticeable impact on good years and increase in poor years, e.g., 37-40 our of
43 years less than 100% PD. For the high scenario this trend will be enhanced and all of the
years could have abundances considerably less than present, with median abundances
ranging between 37-53% of present day.
4.6.4
Indicator 4: Sandbank dwelling fish
Representative species: Sand catlet [Leptoglanis cf dorae]
Summary of characteristics
This group of species lives on actively moving sandbanks and habitats with sandy bottoms.
As such they are dependent on flows that maintain sandbanks. However, the real issue here
is not water but the fact that dams and weirs trap sediment. Downstream of a weir or dam the
river is deprived of sediment, so it erodes its bed, banks and floodplains until it is once again
carrying its maximum load. Thus, for some distance downstream of a weir or dam the
sandbanks will be removed.
These fish are used as indicators for Sites 1, 2, 3, 4, 6 and 7.
Impact of the Water-use Scenarios
It is predicted that these fishes will severely reduced or absent from the Capico River under
the low, medium and high scenarios. The impacts for the low scenario will be minor for the
other sites. Under the median and high scenarios, however, there will be a noticeable impact
on good years and increase in poor years. This is particularly so for the high scenario when
there will be no good years and median numbers will range between 29 and 29% of present.
It is also important to re-emphasise that at Site 2, and to a lesser extent the downstream
sites, the sediment trapped by the dam included in this scenario has not been considered,
and would probably have a major negative impact on the habitat of these species.
4.6.5
Indicator 5: Rock dwelling fish
Representative species: Sand catlet [Leptoglanis cf dorae]
Summary of characteristics
These are rheophillic (flow-loving) species of riffles and rapids, which are usually found living
amongst the rocks and in crevices in strongly flowing water. Unlike some of the other groups
these fish tend to be resident in a particular part of the river and their numbers show much
less marked fluctuations under present day.
These fish are used as indicators for Sites 2, 4 and 5.
Impact of the Water-use Scenarios
It is predicted that flow changes under the low scenario will not seriously affect these fishes.
Under the median and high scenarios, however, there will be a marked increase in the
season and year-on-year fluctuations in numbers of these species, mainly as a result of
reduced flows in the lowflow season and median numbers fall considerably under the high
scenario. This of course assumes that they will have some refuges to which they can retreat
during poor years, which will dominate under the high scenario. It is possible that this will not
be the case, and that over time the numbers of these species will become severely reduced
throughout the system.
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4.6.6
Indicator 6: Marginal vegetation fish
Representative species: Banded tilapia [Tilapia sparrmanii].
Summary of characteristics
This group of species lives mainly amongst vegetation on margins of river and may move into
floodplains during flood conditions. As such they are depend on the presence of marginal
vegetation, stable soils and naturally varying water levels for establishment of emergent and
submerged vegetation.
These fish are used as indicators for Sites 1, 2, 3, 4, 5, 6, 7 and 8.
Impact of the Water-use Scenarios
It is predicted that these fishes will severely reduced or absent from the Capico River (Site 1)
under the low, medium and high scenarios. Under the medium scenario there will be a slight
emphasis on poor years at Site 2 (39 out of 43 years where present there are 14 out of 43).
The situation will be similar at Sites 5, 6, 7 and 8. There no noticeable effect predicted for
Site 4. Under the high scenario the effects on Sites 2 and 4 are likely to be similar as for the
medium scenario, but all the years will be strongly negative at Sites 5 and 6 and there will be
a marked reduction in the abundance of these fishes at Sites 7 and 8 (down to 26-29% of
present).
4.6.7
Indicator 7: Backwater dwelling fish
Representative species: Okavango tilapia [Tilapia ruweti]
Summary of characteristics
This group of species shares a similar habitat with the marginal vegetation group but tends to
be more restricted to vegetated backwater areas and pools. They may also move into
floodplains during flood conditions. Their continued presence is dependent on the
maintenance of oxbows and pools on the margin of the floodplain of the river by the
hydrological regime, including standing-water conditions during low flow.
These fish are used as indicators for Sites 4, 6 and 7.
Impact of the Water-use Scenarios
It is predicted that moving from present day to the low, medium and high scenarios will result
in an increasing loss of the benefits of good years for these species, mainly as a result of the
suppression of flood flows. Under the high scenario there will be a marked reduction in good
years and a corresponding marked reduction in overall numbers at Sites 6 and 7.
4.6.8
Summary of fish responses to scenarios
With the exception of Site 1, where fish losses are expected to be high for all three scenarios,
mainly as a result of run-of-river abstraction during the lowflow season, the fish assemblages
are expected to cope fairly well with the low scenario, and slightly less well with the medium
scenario. Under the high scenario, the fish communities in the lower part of the catchment,
e.g., Sites 4, 5, 6, 7 and 8 are expected to be severely and negatively impacted, and local
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extinctions are highly likely, particularly from Popa Falls (Site 5) downstream to the Boteti
(Site 8).
4.7. Wildlife
4.7.1
Indicator 1: Semi aquatic animals.
Representative species: Hippopotamus, crocodile, otters, monitors and terrapins.
Summary of characteristics
These animals dwell in the main channel, and also range over banks, floodplains and
islands. They are particularly sensitive to dry-season water depths, as they need sufficient
water to maintain their aquatic habitat but not too much so that islands are present. The DSS
predicts that they will increase in abundances in wet cycles and decrease during dry cycles.
These animals are used as indicators for all eight sites.
Impact of the Water-use Scenarios
Under Present Day conditions, the DSS shows that abundances can occasionally climb to
almost double median abundances and fall as low 20% in long dry periods. Under the
scenarios, they are predicted to decline at all sites under all scenarios. The most noticeable
declines will be a permanent drop to very low levels (about 20%) at Capico (Site 1) under
Low Scenario, at Mucundi, Kapako and Panhandle under all scenarios, and at Popa, Delta
and Boteti under the High Scenario.
4.7.2
Indicator 2: Frogs, snakes and small mammals.
Representative species: snakes, ridged frogs, musk shrews.
Summary of characteristics
These animals inhabit pools, permanent swamps and the lowest floodplain areas. They are
particularly sensitive to dry-season water levels and duration, and reduced floods, as they
depend on backwaters and marginal vegetation.
These animals are used as indicators for Sites 2-7.
Impact of the Water-use Scenarios
There is Present Day natural variability in abundances, with modelled drops to as low as 20-
30% of median during dry cycles and some modest increases during wet cycles. The
scenarios are predicted to induce more severe declines during dry periods with populations
probably becoming permanently depressed to levels as low as 10% of median in the High
Scenario. Boteti is predicted to be the site most severely affected.
4.7.3
Indicator 3: Lower floodplain grazers
Representative species: Lechwe, sitatunga, reedbuck, waterbuck.
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Summary of characteristics
The species in this indicator rely on grazing in areas of permanent swamp, and primary and
secondary floodplain. These areas need floods for 4-6 months per year.
The animals are used as indicators for Sites 1-3 and 5-8.They would also have occurred at
Site 4: Kapako, but this is no longer the case and cattle have no replaced them.
4.7.4
Indicator 4: Middle floodplain grazers
Representative species: elephant, buffalo, tsesebe, warthog.
Summary of characteristics
This guild of animals depends for grazing on primary and secondary floodplains, which flood
for 2-6 months per year.
These animals are used as indicators for Sites 2, 3, 5, 7 and 8.
Impact of the Water-use Scenarios
This indicator group fares best in years with good flooding, and Present Day abundances are
thought to decline in dry cycles. They range in abundance between about 50% and 180% of
median values from year to year, and are most abundant in the Delta in years where
permanent swamps shrink and seasonal wetlands expand. They disappear from the Boteti in
dry cycles. They are predicted to progressively decline in abundance through the scenarios,
to eventually disappear or remain at very low numbers by the High Scenario except in the
Delta where they should progressively increase in numbers.
4.7.5
Indicator 5: Outer floodplain grazers
Representative species: Wildebeest, zebra, impala, duiker, aarvark, mice.
Summary of characteristics
This group of animals relies for grazing on secondary and tertiary floodplains that must flood
periodically.
They are used as indicators for Sites 1-3 and 5-8.
Impact of the Water-use Scenarios
This indicator group is thought to increase in abundance in wet years and decrease in dry
cycles. Present Day abundances could drop to 50% or less of median and possibly double in
wet cycles. In the Delta the species thrive when permanent swamps shrink and seasonal
wetlands expand, and they disappear from the Boteti as it dries out. In the scenarios they
would progressively decline in numbers at all sites except the Delta, possibly becoming
locally extinct in parts of the basin under the High Scenario. In the Delta, they are predicted
to benefit from the scenarios, showing up to three-fold increases under the High Scenario.
Impact of the Water-use Scenarios
The species in this group are thought to increase along the river in wetter years to up to 50%
more than Present Day median values, and decline in dry cycles to perhaps as low as a fifth
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of the PD median. They increase in numbers in the Delta in drier years as permanent
swamp shrinks and seasonal wetlands expand, and disappear from the Boteti in dry periods.
The scenarios are predicted to permanently depress abundances to very low levels along the
river perhaps for some sites and species to as low as 5% of PD median, with the most
severe declines being associated with the High Scenario. Abundances along the Boteti will
have significantly more years of low or no abundances. Populations in the Delta are
expected to increase slightly or remain stable through the Low and Medium Scenarios, but
decline under the High Scenario as seasonal wetlands shrink and savanna expands.
4.7.6
Summary of wildlife responses to scenarios
Abundances of wildlife are predicted to decline progressively through the scenarios, with the
High Scenario having the most severe impact. Some species at some sites could
permanently decline to as low as 5% of Present Day medians. The notable exception to this
is the Delta, where the three indicator groups of grazers would benefit from the scenarios as
permanent swamp gave way to seasonal floodplains, but even they may show an eventual
decline as wetlands give way to savanna. Many of the wildlife species no longer occur at the
other floodplain sites, but in areas where they do occur, similar patterns would be expected in
response to the scenarios.
4.8. Birds
4.8.1
Indicator 1: Piscivores of open water.
Representative species: kingfisher, cormorant, darter, fish eagle.
Summary of characteristics
This group of birds predominantly feeds on fish from the river and adjacent pools. They
generally thrive in times of low flow because their fish prey is more concentrated and
vulnerable in the main river and/or isolated pools. The DSS indicates that present-day
conditions produce more variability in abundances in the higher parts of the basin than in the
lower parts, and abundances are generally lower in wet years and higher in drier years. If
low flows are prolonged, however, the prey base will be negatively affected if the floodplains
where fish breed are not inundated.
These birds are used as indicators for all eight sites.
Impact of the Water-use Scenarios
Higher abundances are generally favoured under the Low, Medium and high scenarios, but
the high scenario is detrimental in the Boteti (Site 8). Here, abundances under this scenario
are predicted to fall drastically, possibly to local extinction, as the river tends toward drying
out.
4.8.2
Indicator 2: Piscivores of shallow waters
Representative species: larger herons and egrets.
Summary of characteristics
These birds hunt fish from overhanging trees on shallow backwaters using ambush
techniques. Under Present Day conditions, the DSS indicates that their numbers tend to be
lower in drier years, with good variability from year to year and many years with above
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median abundances. In the lower part of the basin they are less abundant in the lagoon and
savanna parts of the Delta/Boteti and rather favour the seasonally flooded areas. Shallow
waters in the main channels and on the floodplains concentrate the prey species into smaller
areas and hunting opportunities are thus better than in lagoon areas.
These birds are used as indicators for all eight sites.
Impact of the Water-use Scenarios
Under the low scenario, this guild of birds is predicted to disappear from Site 1 (Capico) after
a few years. The guild would also disappear from Site 2 (Mucundi) in all three scenarios
within a decade or two. Further downstream, they would not be noticeably impacted by any
of the scenarios, with the following two exceptions: 1) there would be an estimated and
permanent 20% drop in numbers at Site 5 (Popa) under the high scenario; and 2) there
would be a sequential decline in abundance to an eventual loss of more than half the present
median abundances at Site 8 (Boteti) under the high scenario due to increased extent and
time of drying out of the river.
4.8.3
Indicator 3: Piscivores and invertebrate feeders
Representative species: Little Egret, Black Heron, Glossy Ibis, Saddle-billed Stork, Lapwings.
Summary of characteristics
This group of birds feeds on fish-fry and invertebrates when water levels are receding after
spawning in flood-plains; they also feed on fish trapped in drying pools. They respond to the
flooding and draining of floodplains, when feeding conditions are optimal, and tend to be
more abundant in wetter years.
These birds are used as indicators for all eight sites.
Impact of the Water-use Scenarios
As with the previous indicators, this group is predicted to disappear from Site 1 (Capico)
under the low scenario and will decline to low levels at Site 2 (Mucundi) with the medium
scenario causing the greatest decline to very low abundances. They will continue to respond
normally to wet and dry cycles, with abundances increasing up to four-fold of their median
value in very wet periods and decreasing down to half or less in drier times. The range of
abundances between wet and dry climatic periods will noticeably shrink with the high
scenario and the lower level of abundances decline to about one-fifth of median, particularly
at Site 6 (Panhandle). They should increase in abundance in the Delta (Site 7) due to the
loss of permanent swamp and increase in seasonal flooded areas, but disappear from the
Boteti (Site 8) under the high scenario.
4.8.4
Indicator 4: Specialists of floodplains
Representative species: African Openbill, ducks, geese, Wattled Crane.
Summary of characteristics
This group of birds feeds on molluscs, frogs, fish or selective vegetation and organisms
occurring in shallow floodplains. They utilise newly-flooded floodplains because food
availability is optimal due to new breeding and germination activities. They also take
advantage of times when waters are receding from floodplains and food items are confined
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and concentrated into smaller areas. Thus, times of both new inundation and receding of
waters are vitally important to them. Abundances increase in wet years and decrease in dry
years.
These birds are used as indicators for Sites 2, and 4-8. They were not used as indicators for
Site 3 due to lack of information.
Impact of the Water-use Scenarios
The group is not listed for Site 1 (Capico) or for Site 3 (Cuito Cuanavale). At the other river
sites, under Present Day conditions, they have a wide range of abundances: up to 230% of
median in wet cycles and down to 3% in very dry cycles. These fluctuations become more
violent with advancing development at Sites 2 (Mucundi) and 4 (Kapako), leading to no years
of good abundances and possible local complete loss under the Medium and high scenarios.
Populations are predicted to be more stable at Sites 5 (Popa) and 6 (Panhandle) and 7
(Delta), but declining to local loss in the Boteti (Site 8) under all scenarios.
4.8.5
Indicator 5: Specialists of water-lily habitats
Representative species: African and Lesser Jacanas.
Summary of characteristics
This group frequents floodplain pools, in both rising and receding water levels, and also lily-
pad covered inlets, both of which are essential feeding habitats. Whatever the flood regime,
pockets of water lilies generally survive, either in backwaters, lagoons or isolated pools,
providing suitable habitat for these birds, and so they appear less vulnerable to flow changes
than some other indicators.
These birds are used as indicators for Sites 2-7.
Impact of the Water-use Scenarios
The group is not reported to occur at Site 1. At Sites 3 and 4, the species are predicted to
increase to quite high abundances in Present Day wet cycles (up to 353% of median
abundances) and decrease slightly in dry years. The range of variability in Present Day
abundance is less at Site 2 (87-105%) and Sites 5-8 (59-150%). This pattern is repeated
through the scenarios, with years of higher abundance gradually becoming rarer and less
pronounced. Under the high scenario, abundance levels are permanently depressed, mostly
never reaching present-day median abundance levels. However, they do not decline to close
to disappearance, except in the Boteti (Site 8) where they drop to perhaps 5% for all
scenarios due to drying out of the river.
4.8.6
Indicator 6: Specialists inhabitants of riparian fruit trees
Representative species: Turacos, bulbuls.
Summary of characteristics
This group of birds are specialist frugivores in riparian fruit trees; when the trees are in fruit
they are an important food source for many bird species. The birds are indirectly influenced
by changes in water flows because they depend on the fruit-bearing riparian trees, which in
turn respond to changes in water flows. Because most of the trees are long-lived, there will
be a time lag of several years after the onset of unfavourable flows before fruit production
fails and the trees start dying from lack of water. Abundance of the birds should mirror to
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some extent that of the trees since if the trees die due to low flows, there will not be a source
of food for the birds.
These birds are used as indicators for Sites 2-7.
Impact of the Water-use Scenarios
Abundances are predicted to increase in wet cycles and decrease in dry years. The Present
Day abundances can drop to half of median in dry years and increase to more than double
the median in wet years, except at Site 4 (Kapako) where they can drop to very low (<10%)
in long dry spells. With basin development, Capico (Site 2), Kapako and the Panhandle (Site
6) appear to be the most vulnerable sites, with population abundances dropping steadily to
reach close to zero in the high scenario. This guild is predicted to benefit from basin
development in the Delta, as open water shrinks and is replaced by sedge lands and
grasslands, but would show a progressive decline at Site 8 (Boteti) to about half of Present
Day median abundances.
4.8.7
Indicator 7: Breeders in reedbeds and floodplains
Representative species: Fan-tailed widowbird, weavers, bishops, herons and egrets.
Summary of characteristics
This guild of birds relies on reedbeds lining river banks and islands, and other vegetation that
stands in water, for nest-building. This is a protective mechanism against predator access to
their nests. The birds generally wait for high water levels before constructing nests, so that
their nests do not become flooded and so that the water level stays high throughout the
breeding cycle. The DSS predicts that they increase in abundance in wet years and decline
in dry years.
These birds are used as indicators for Sites 1-7.
Impact of the Water-use Scenarios
At Sites 1 (Capico) and 4 (Kapako) the species show good response to dry and wet periods
under Present Day conditions, with high variability from year to year leading to a wide range
of abundances. The range is more muted at Sites 2 (Mucundi) 5 (Popa) and 7 (Delta) and
the guild does not occur at Site 8 (Boteti). The range and variability of abundances reduces
progressively through the scenarios: the species are expected to disappear from Site 1 under
all scenarios because of the almost non-existent dry-season flows, and to reduce to low
levels at Site 2 (1-15% of Present Day medians) and Site 6 (about 50%). This is probably
because upstream developments would affect suitable nesting habitat through erratically
changing water levels. The guild appears to be less affected at Sites 4 and 5 and even to
benefit under the high scenario in the Delta (Site 7), presumably because of the loss of
lagoons and spread of seasonal grass and sedge lands.
4.8.8
Indicator 8: Breeders in overhanging trees
Representative species: Herons, cormorants, darters.
Summary of characteristics
These species are colonial breeders or solitary nesters in trees hanging over the water. The
trees are critical to their breeding success, providing protection against predators, safety for
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E-Flows Ecological and Social Predictions Scenario Report
the nest and a refuge for chicks as they begin to vacate the nest. They should not be
affected by changing flows in this aspect of their lives as long as the trees are not affected.
These birds are used as indicators for Sites 1-7.
Impact of the Water-use Scenarios
Their abundances are predicted to increase in wet cycles and decrease in dry cycles. The
response is through a larger range at Sites 1, 3 and 4 (up to 336% increase and down to 6%
over the years), and is more muted with more years at median values at Sites 5 and 6.
Abundances will decline progressively through the scenarios, with no or virtually no above-
median years at Sites 2, 5 and 6 under Medium and High Development. The exception to
this trend is the Delta (Site 7), where the guild may experience beneficial conditions and
some increase due to the increase in sedge and grasslands.
4.8.9
Indicator 9: Breeders in banks
Representative species: Bee-eaters, Collared Pratincoles, lapwings.
Summary of characteristics
This guild of birds requires vertical banks for nest holes or grassy banks for nest sites and
fledgling development (note that kingfishers have been excluded). The birds need reliably
lowering water levels that expose vertical or grassy banks for breeding. They are not
necessarily dependent on flow for their food supply, but will be affected if changing flows
influence the moisture level and texture of the bank materials or if unexpected high flows
flood their nests. The guild has not been included for Sites 1, 2 and 8.
These birds are used as indicators for Sites 3-7.
Impact of the Water-use Scenarios
The direct impacts of flow changes are predicted to be very mild, with the high scenario
showing mostly above-median abundances at Sites 4, 5, 6 and 7. It must be noted, however,
that the indirect affects of flow changes, such as changing bank conditions and possible
surges of unseasonal higher flow from dam releases that swamp nests have not been
assessed.
4.8.10
Indicator 10: Breeders on rocks and sandbars
Representative species: Rock Pratincole, African Skimmer, sandpipers, thick-knees.
Summary of characteristics
These species are totally dependent for nesting on rocks, sandbars and islands in the main
river that emerge above the water. Low flow levels generally benefit them, as this is the time
when sandbanks and rocks are exposed for breeding. Very low flows will result in
sandbanks becoming accessible to predators, however, and negatively affect the food supply
of those that eat floodplain-breeding fish. Unseasonal high flows could swamp nests.
These birds are used as indicators for Sites 1, and 5-7.
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E-Flows Ecological and Social Predictions Scenario Report
Impact of the Water-use Scenarios
The guild has not been listed for Sites 2, 3, 4 and 8. The different species could occur
wherever rocks or sandbars emerge from the water. They will generally benefit from lower
flows as more rocks and sandbars will be exposed, but it is predicted that their numbers will
decline at Site 5 (Popa) under the high scenario, perhaps because dry-season flows fall
extremely low to 18% of Present Day thereby exposing nesting sites to predators.
4.8.11
Summary of bird responses to scenarios
Sites 1 (Capico), 2 (Mucundi), 4 (Kapako), 6 (Panhandle) and 8 (Boteti) are identified as river
reaches where local extinctions of one or more indicator groups could occur, especially under
the high scenario. The same sites also most often list moderate declines in several
indicators if local extinction is not anticipated. Site 7, conversely, is predicted to have mild to
moderate increases in several indicators as open water and permanent swamp give way to
seasonal grass and sedge lands.
It is worth noting that birds are highly mobile and will soon arrive when conditions become
favourable or leave when they are unfavourable. This implies that there are other areas for
them to arrive from or depart to. Development in the Okavango Basin, however, will probably
be mirrored by that in other nearby basins such as the Zambezi River, and it cannot be
assumed that there will always be suitable habitat elsewhere. The Okavango River is a vital
part of the southern African mosaic of wetlands that supports both resident and migrant birds,
and would need to maintain that status to ensure their long-term viability.
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E-Flows Ecological and Social Predictions Scenario Report
5.
Biophysical results: Integrity
5.1.
Integrity ratings and classification of overall impact
The predictions presented in the previous Chapter were generated from the information
provided by the biophysical specialists in the form of Response Curves. This is essentially a
set of consequences for a particular indicator to changes in a range of flow categories
expressed as Severity Ratings of that describe increase/decreases for an indictor on a scale
of 0 (no measurable change) to 5 (very large change; see Section 1.3). These rating were
then taken further to indicate whether that change would be a shift toward or away from the
natural condition. The Severity Ratings hold their original numerical value of between 0 and
5, but are given an additional negative or positive sign, to transform them from Severity
Ratings (of changes in abundance or extent) to Integrity Ratings (of shift to/away from
naturalness), where (Brown and Joubert 2003):
· toward natural is represented by a positive Integrity Rating; and
· away from natural is represented by a negative Integrity Rating.
The Integrity Ratings were then used to place the three flow scenarios within a classification
of overall discipline integrity and overall river condition, using the South African
ecoclassification categories A to F (Table 5.1; DWAF 1999; Kleynhans 1996; Brown and
Joubert 2003). The ecological integrity of a river is defined as its ability to support and
maintain a balanced, integrated composition of physico-chemical and habitat characteristics,
as well as biotic components on a temporal and spatial scale that are comparable to the
natural characteristics of ecosystems of the region.
Table 5.1.
The South African River Categories (DWAF 1999)
CATEGORY DESCRIPTION
A Unmodified,
natural.
Largely natural with few modifications. A small change in natural habitats and
B
biota may have taken place but the ecosystem functions are essentially
unchanged.
Moderately modified. A loss and change of natural habitat and biota have
C
occurred but the basic ecosystem functions are still predominantly unchanged.
Largely modified. A large loss of natural habitat, biota and basic ecosystem
D
functions has occurred.
E
The loss of natural habitat, biota and basic ecosystem functions is extensive.
Modifications have reached a critical level and the lotic system has been modified
completely with an almost complete loss of natural habitat and biota. In the worst
F
instances the basic ecosystem functions have been destroyed and the changes
are irreversible.
Note : A D-category is widely considered to represent the lower limit of degradation
allowable under sustainable development (e.g., Dollar et al. 2006; Dollar et al. In
press).
In this study, the predictions provided by the specialists for each of the three were
summarized in terms of their effects on the integrity of each discipline at each study site and
the overall riverine ecosystem represented by each study site. If the present status of a river
is say a B-category, a scenario with a negative Integrity Score would represent movement in
the direction of a Category C-F river, whilst one with a positive score would indicate
movement toward a Category A river.
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E-Flows Ecological and Social Predictions Scenario Report
5.2.
Present-day ecological integrity for the study sites
The present day ecological integrity of the aquatic ecosystems at each of the eight study
sites was determined using a Habitat Integrity Assessment (Kleynhans 1996). The Habitat
Integrity Method uses easily assessed physico-chemical and habitat characteristics as
surrogates for physical and biotic condition. The method is based on the qualitative
assessment of a number of pre-weighted criteria that indicate the integrity of the instream
and riparian habitats available for use by riverine biota (Table 5.2). The criteria used are the
basis that anthropogenic modification of their characteristics can generally be regarded as
the primary causes of degradation of the integrity of a river.
The assessment of the severity of impact of modifications is based on six descriptive
categories with ratings ranging from 0 (no impact), 1 to 5 (small impact), 6 to 10 (moderate
impact), 11 to 15 (large impact), 16 to 20 (serious impact) and 21 to 25 (critical impact).
The assessment was done using the professional judgement and experience of the study
team, and was conducted on-site at each of the study sites. Assessments were made
separately for instream and riparian components, and then combined and expressed as a
percentage and subtracted from 100 to produce a score for overall Habitat Integrity.
Table 5.2
Criteria and weights used for the assessment (from Kleynhans 1996).
INSTREAM CRITERIA
WEIGHT RIPARIAN ZONE CRITERIA
WEIGHT
Water abstraction
14
Indigenous vegetation removal
13
Flow modification
13
Exotic vegetation encroachment 12
Bed modification
13
Bank erosion
14
Channel modification
13
Channel modification
12
Water quality
14
Water abstraction
13
Inundation
10
Inundation
11
Exotic macrophytes
9
Flow modification
12
Exotic fauna
8
Water quality
13
Solid waste disposal
6
TOTAL 100
TOTAL
100
The results of the assessments are presented in Table 5.3. The total scores for the instream
and riparian zone components are then used to place the habitat integrity of both in a specific
intermediate habitat integrity category. These categories are also indicated in Table 5.3.
79
Table 5.3
Results of the Habitat Integrity (after Kleynhans 1996) assessments done on-site by the biophysical specialists at each of the study sites
(October 2008)
y
y
s
nt
n
io
me
hyte
h
tegor
Integrit
ws
al
r
r
a
ct
nel
e
st
a
bitat
b
a
st
mov
Site No
Rive
Place
PD Ca
H
Instream
Riparian
A
Quality
Floods
Lowflo
Bed
Chan
Inundation
Macrop
Fish
W
Re
Encroac
Erosion
1 Cuebe Capico
B 84.1 91.7
76.48 8 0 0 5 0 5 0 0 0 0 18 0 5
2 Cubango
Mucundi
B
87.3 92.8
81.76 6 0 0 5 0 5 0 0 0 0 16 0 0
3 Cuito Cuito
Cuanavale
B
91.0 93.5
88.52 0 1 0 5 1 5 1 0 0 5 12 0 0
4 Okavango
Kapako
B
86.2 86.6
85.72 5 7 0 0 8 0 0 1 0 9 16 1 0
5 Okavango
Popa
Falls B
91.2 92.6
89.72 2 3 0 0 0 1 0 0 0 17 11 0 2
6 Okavango
Panhandle B
93.5 96.7
90.28 2 2 0 0 0 2 0 0 0 0 11 0 0
7 Okavango
Xaxanaka B
98.6 98.3
98.88 2 1 0 0 0 0 0 0 0 0 0 0 0
8 Boteti Maun
B
88.2 88.5
87.88 6 6 0 4 3 3 0 2 0 0 9 0 0
Where:
A Category = 100
B Category = 80-99
C Category = 60-79
D Category = 40-59
E Category = 20-39
F Category = 0-19.
80
Additional details for the method used are provided in Report 03/2009: Guidelines for data
collection, analysis and scenario creation.
5.3.
Interpretation of integrity plots
The integrity plots presented in this Chapter list each of the study sites (1-8) along the x-axis,
and the Overall Integrity Rating on the y-axis. Zero on the y-axis equals the present day
integrity of the system. Since all of the study sites have a present-day integrity of a B
category, zero on the y-axis equals a B-category.
There is a series of lines marked on the integrity plot representing the general position on the
graph when the overall integrity ratings would be expected to result in a move from one
category to the next.
5.4.
Effects on the integrity of each discipline
The present-day (2008) integrity was a B-category for all disciplines.
5.4.1 Geomorphology
The integrity plot for geomorphology for the three scenarios at each of the study sites is
shown in Figure 5.1.
5
Geomorphology
4
3
2
g
ti
n
a
R 1
r
i
ty
g
te 0 PD
PD
l
l
In
r
a
v
e -1
O
-2
-3
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD Sim
Low Dev
Med Dev
High Dev
B to C
C to D
D to E
E to F
Figure 5.1
Integrity plot for geomorphology for the three scenarios at each of the study
sites
The impacts on geomorphological integrity for the low medium and high scenarios can be
summarised as follows:
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E-Flows Ecological and Social Predictions Scenario Report
Site 1 (Capico):
Drop of two categories from a B-category to a D-category for all
scenarios.
Site 2 (Mucundi):
A drop of one category to a C-Category for the low and high
scenarios, and a drop of two categories to a D-Category for the
mdeium scenario.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
A drop of half a category to a B/C for the low scenario, and a
drop of two categories to a C-category for the medium and high
scenarios.
Site 5 (Popa Falls):
No change in category.
Site 6 (Panhandle):
No change in category for the low and medium scenario and a
drop of one catgeory to a C-category for the high scenario.
Site 7 (Xaxanaka):
No change for the low and medium scenarios. Drop of one
category from a B-category to a C-category for the high
scenario.
Site 8 (Boteti):
Geomorphology not assessed for the Boteti.
5.4.2 Water
Quality
The integrity plot for water quality for the three scenarios at each of the study sites is shown
in Figure 5.2.
5
Water Quality
4
3
2
a
t
i
n
g
1
t
y
R
PD
n
t
egri 0 PD
l
I
-1
v
eral
O
-2
-3
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD Sim
Low Dev
Med Dev
High Dev
B-C
C-D
D-E
E-F
Figure 5.2
Integrity plot for water quality for the three scenarios at each of the study sites
The impacts on water quality integrity for the low medium and high scenarios can be
summarised as follows:
Site 1 (Capico):
Drop of two categories from a B-category to a D-category for all
scenarios.
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E-Flows Ecological and Social Predictions Scenario Report
Site 2 (Mucundi):
Drop of half a category from a B-category to a B/C-category for
the low and medium scenarios, and a drop of one category to a
C-category for the high scenario.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
Drop of a category from a B-category to a C-category for the
low scenario, and slightly greater drop but still only one
category to a C-category for the medium and high scenarios.
Site 5 (Popa Falls):
Drop of half a category from a B-category to a B/C-category for
the low and medium scenarios. Drop of one category to a C-
category for the high.
Site 6 (Panhandle):
Drop of half a category from a B-category to a B/C-category for
the low scenario. Drop of nearly one category to a C-category
for the medium scenario, and a drop of two categories to a D-
category.
Site 7 (Xaxanaka):
No change for the low and medium scenarios, but a drop of two
categories to a D-category for the high scenario.
Site 8 (Boteti):
No significant change in water quality, mainly because the river
is predominately dry under the medium and high scenarios.
5.4.3 Vegetation
The integrity plot for vegetation for the three scenarios at each of the study sites is shown in
Figure 5.3.
The impacts on vegetation integrity for the low medium and high scenarios can be
summarised as follows:
Site 1 (Capico):
Drop of two categories from a B-category to a D-category for all
scenarios.
Site 2 (Mucundi):
Drop of half a category from a B-category to a B/C-category for
the low and high scenarios, and a drop of one category to a C-
category for the medium scenario.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
No change for the low scenario, and a drop of half a category
from a B-category to a B/C-category for the medium and high
scenarios.
Site 5 (Popa Falls):
No change for the low and medium scenarios, but a drop of two
and half categories from a B-category to a D/E-category for the
medium and high scenarios.
Site 6 (Panhandle):
No change for the low and medium scenarios, but a drop of one
category from a B-category to a C-category for the medium and
high scenarios.
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E-Flows Ecological and Social Predictions Scenario Report
5
Vegetation
4
3
2
i
n
g
at
1
i
t
y
R
egr
PD
PD
nt 0
l
I
al
v
er -1
O
-2
-3
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD Sim
Low Dev
Med Dev
High Dev
B-C
C-D
D-E
E-F
Figure 5.3
Integrity plot for vegetation for the three scenarios at each of the study sites
Site 7 (Xaxanaka):
No change for the low and medium scenarios, but a drop of one
category from a B-category to a C-category for the high
scenario.
Site 8 (Boteti):
Drop of half a category from a B-category to a B/C-category for
the low scenario, a drop of two categories to a D-category for
the medium scenario and a drop of three categories to an E-
category for the high scenario.
5.4.4 Aquatic
macroinvertebrates
The integrity plot for aquatic macroinvertebrates for the three scenarios at each of the study
sites is shown in Figure 5.4.
The impacts on aquatic macroinvertebrate integrity for the low medium and high scenarios
can be summarised as follows:
Site 1 (Capico):
Drop of three categories from a B-category to an E-category for
all scenarios.
Site 2 (Mucundi):
No change in category.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
No change in category.
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E-Flows Ecological and Social Predictions Scenario Report
5
Invertebrates
4
3
2
a
t
i
n
g
1
t
y
R
PD
PD
n
t
e
gri
0
l
l
I
v
era -1
O
-2
-3
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD Sim
Low Dev
Med Dev
High Dev
B-C
C-D
D-E
E-F
Figure 5.4
Integrity plot for aquatic macroinvertebrates for the three scenarios at each of
the study sites
Site 5 (Popa Falls):
No change for the low and medium scenarios, and a drop of
half a category from a B-category to a B/C-category for the high
scenario.
Site 6 (Panhandle):
No change for the low and medium scenarios, and a drop of two
categories from a B-category to a D-category for the high
scenario.
Site 7 (Xaxanaka):
No change for the low and medium scenarios, and a drop of
one category from a B-category to a C-category for the high
scenario.
Site 8 (Boteti):
Drop of half a category from a B-category to a B/C-category for
the low scenario, a drop of three categories to an E-category for
the medium scenario and a drop of four categories to an F-
category for the high scenario.
5.4.5 Fish
The integrity plot for fish for the three scenarios at each of the study sites is shown in Figure
5.5.
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E-Flows Ecological and Social Predictions Scenario Report
5
Fish
4
3
2
a
ti
n
g
R 1
g
r
i
t
y
te 0 PD
PD
v
e
r
a
l
l
In
-1
O
-2
-3
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD Sim
Low Dev
Med Dev
High Dev
B-C
C-D
D-E
E-F
Figure 5.5
Integrity plot for fish for the three scenarios at each of the study sites
The impacts on fish integrity for the low medium and high scenarios can be summarised as
follows:
Site 1 (Capico):
Drop of four categories from a B-category to an F-category for
all scenarios.
Site 2 (Mucundi):
Drop of one category from a B-category to a C-category for the
low scenarios, and a drop of two categories to a D-category for
the medium and high scenarios.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
A drop of half a category to a B/C for the low scenario, and a
drop of one category to a C for the medium and high scenarios.
Site 5 (Popa Falls):
No change for the low scenario. A drop of one category to a C-
category for the medium scenario, and a drop of three
categories to an E-category for the high scenario.
Site 6 (Panhandle):
No change for the low scenario. A drop of one category to a C-
category for the medium scenario, and a drop of three
categories to an E-category for the high scenario.
Site 7 (Xaxanaka):
Drop of half a category from a B-category to a B/C-category for
the low scenario, a drop of one category to an C-category for
the medium scenario and a drop of four categories to an F-
category for the high scenario.
Site 8 (Boteti):
Drop of half a category from a B-category to a B/C-category for
the low scenario, a drop of three categories to an E-category for
the medium scenario and a drop of four categories to an F-
category for the high scenario.
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E-Flows Ecological and Social Predictions Scenario Report
5.4.6 Wildlife
The integrity plot for wildlife for the three scenarios at each of the study sites is shown in
Figure 5.6.
5
Wildlife
4
3
2
i
n
g
at
1
i
t
y
R
PD
n
t
e
gr
0
PD
l
I
v
e
r
al
-1
O
-2
-3
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD Sim
Low Dev
Med Dev
High Dev
B-C
C-D
D-E
E-F
Figure 5.6
Integrity plot for wildlife for the three scenarios at each of the study sites
The impacts on wildlife integrity for the low medium and high scenarios can be summarised
as follows:
Site 1 (Capico):
Drop of four categories from a B-category to an F-category for
all scenarios.
Site 2 (Mucundi):
Drop of one category from a B-category to a C-category for the
low scenario, and a drop of two categories to a D-category for
the medium and high scenarios.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
A drop of one category to a C-category for the low scenario. A
drop of two categories to a D-category for the medium scenario.
The high scenario scored between the low and medium
scenario.
Site 5 (Popa Falls):
A drop of half a category to a B/C-Category for the low
scenario. A drop of one category from a B-category to a C-
category for the medium scenario, and a drop of three
categories to an E-category for the high scenario.
Site 6 (Panhandle):
A drop of half a category to a B/C-Category for the low
scenario. A drop of one category from a B-category to a C-
category for the medium scenario, and a drop of two categories
to an D-category for the high scenario.
Site 7 (Xaxanaka):
No change for the low and medium scenarios. A drop of two
and a hald categories to a D/E-Category for the high scenario.
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E-Flows Ecological and Social Predictions Scenario Report
Site 8 (Boteti):
No major change for the low scenario. A drop of two categories
to a D-category for the medium scenario, and a drop of four
categories to an F-category for the high scenario.
5.4.7 Birds
The integrity plot for birds for the three scenarios at each of the study sites is shown in Figure
5.7.
5
Birds
4
3
g 2
a
t
in
1
n
t
e
g
r
it
y
R
0 PD
PD
v
e
r
a
ll I
-1
O
-2
-3
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD Sim
Low Dev
Med Dev
High Dev
B to C
C to D
D to E
E to F
Figure 5.7
Integrity plot for birds for the three scenarios at each of the study sites
The impacts on bird integrity for the low medium and high scenarios can be summarised as
follows:
Site 1 (Capico):
Drop of three categories from a B-category to a an E-category
for all scenarios.
Site 2 (Mucundi):
Drop of one category from a B-category to a C-category for the
low scenario, and a drop of two categories to a D-category for
the medium and high scenarios.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
No change for the low scenario. A drop of half a category to a
B/C-category for the medium scenario and a drop of one
category to a C category for the high scenario.
Site 5 (Popa Falls):
No change for the low scenario. A drop of half a category to a
B/C-category for the medium and high scenarios.
Site 6 (Panhandle):
A drop of half a category to a B/C-category for the low and
medium scenarios and a drop of one category to a C category
for the high scenario.
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E-Flows Ecological and Social Predictions Scenario Report
Site 7 (Xaxanaka):
A drop of half a category to a B/C-category for the low and
medium scenarios and a drop of one category to a C category
for the high scenario.
Site 8 (Boteti):
A dopr of half a category to a B/C for the low scenario. A drop
of two and a half categories to a D/E-category for the medium
scenario, and a drop of four categories to an F-category for the
high scenario.
5.5.
Effects on the integrity of the whole ecosystem
The plot for overall ecosystem integrity for the three scenarios at each of the study sites is
shown in Figure 5.8.
OVERALL INTEGRITY
0
-1
g
t
i
n
a
-2
r
i
t
y R
t
eg
l
I
n
al
er
v
-3
O
-4
-5
SITE 1
SITE 2
SITE 3
SITE 4
SITE 5
SITE 6
SITE 7
SITE 8
PD
LOW DEV
MED DEV
HIGH DEV
B to C
C to D
D to E
E to F
Figure 5.8
Overall ecosystem integrity for the three scenarios at each of the study sites
The impacts on overall ecosystem integrity for the low medium and high scenarios can be
summarised as follows:
Site 1 (Capico):
Drop of three categories to a E-category for all scenarios.
Site 2 (Mucundi):
Drop of one category to a C-catgeory for all three scenarios,
although the low scenario results in a mcuh higher C than the
other two.
Site 3 (Cuito Cuanavale):
No change.
Site 4 (Kapako):
Drop of half and category to a B/C-category for the low
scenario, and a drop of one category to a C-category for the
medium and high scenarios.
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E-Flows Ecological and Social Predictions Scenario Report
Site 5 (Popa Falls):
No change for the low scenario. Drop of half a category to a
B/C-category for the medium scenario, and a drop of one and a
half categories to a C/D-category for the high scenario.
Site 6 (Panhandle):
No change for the low scenario. Drop of half a category to a
B/C-category for the medium scenario, and a drop of two
categories to a D-category for the high scenario.
Site 7 (Xaxanaka):
No change for the low scenario. Drop of half a category to a
B/C-category for the medium scenario, and a drop of two
categories to a D-category for the high scenario.
Site 8 (Boteti):
Drop of half a category to a B/C-category for the low scenario.
A drop of two categories to a D-category for the medium
scenario, and a drop of three categories to an E-category for
the high scenario.
Thus, apart from Site 1: Capico, the greatest impacts on integrity are for the high scenario at
Sites 5, 6, 7 and 8 (Figure 5.9). Importantly, the situation in Capico is one of local impacts
and locally accrued benefits, whereas the water-use benefits associated with the medium
and high scenarios at Sites 5, 6 and 7 are expected to accrue outside of the basin and, for
Botswana, outside of the country. This is also true for the low and medium scenarios in the
Boteti, while the high scenario at Boteti include a dam at Samedupi, which should deliver
local water-use benefits.
In Figure 5.9, those sections of the river in a D-category and in an E-category have been
marked with a red flag. This is because the expected decline in their condition is likely to
result in difficulties in sustaining the benefits offered by theses ecosystems. This is
particularly so given the fact that neither the localised impacts of the water-resource
developments themselves (such as sediment changes) nor the longitudinal impacts of a
fragmented river system have been considered in these predictions.
Low
Medium
High
A
B
C
D
E
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Figure 5.9
Summary of expected changes in ecosystem integrity for the low, medium and
high scenarios. Present-day conditions are estimated as B-category.
6. Social
results
6.1. Introduction
The chapter summarises the results for each of the socio-economic indicators in terms of
their overall contribution to the livelihoods of the people in the basin, as well as their
contribution to the economies of the basin countries. Livelihoods are measured in terms of
net income earned by households in the basin. Economic contributions are measured in
terms of the change in national income generated by the use of the indicators concerned.
6.1.1
Indicator 1: Household income - fish
Summary of characteristics
Fish are caught throughout the basin in river channels, floodplains during floods, and residual
floodplain pools. Seasonal floods can bring a marked peak in catch. Only in Botswana and
only in the Panhandle area is fishing done commercially in groups of semi-motorised small
scale fishers. Elsewhere fishing is small scale at household level and traditional gear (locally
made traps), gill nets hook, and line and dugout canoes are used. It is a small-scale
household-based fishing activity, using traps, and/ or gill nets, hook and line and mokoros
(canoes), for own use as fresh food product, and very limited marketing, with very limited
processing (drying). Species caught a numerous dominated by vegetarian and predatory
bream (Cichlidae), tiger, and barbel (Claridae). Fish catch is dependent on fish abundance -
perennial flows in channels, regular seasonal floods on floodplains.
Used as indicator for Sites 1 to 12 (all sites).
Impact of the Water-use Scenarios
The catch tends to peak during floods in areas with floodplains. In areas without floodplains
catches are more stable. At prolonged low flows or excessively low flows fish abundance will
be negatively affected if the floodplains where fish breed are not inundated. Generally the
scenarios will progressively reduce catch. In the lower basin the high scenario will severely
reduce fish catch. The net incomes for fishers or livelihoods tend along with catches to peak
during floods in areas with floodplains. In the areas without net incomes are more stable.
The relatively simple small scale enterprise is not particularly sensitive to catch reduction and
so the patter is similar to that for catch.
6.1.2
Indicator 2: Household reeds
Summary of characteristics
Reeds and sedges are harvested from the wetter parts of floodplains and riverbanks, and
used for building, and craft making. The representative species is Phragmites australis.
Reeds are subject to small-scale household-based harvesting of reeds using sickles, for own
use in housing and compound wall construction, and very limited marketing. It is found in
upper wetbank 1 and river lower floodplain situations, and relies on the perennial flows in
channels, regular seasonal floods on upper wetbank 1, and river lower floodplain.
Used as indicator for Sites 1 to 7 (all sites except 8).
Impact of the Water-use Scenarios
Reeds occur in two indicator vegetation sites; upper wetbank, and lower floodplain, and are
harvested at both. Harvest response is complex and tends to reflect change in the extent of
these stands. Also making it complex is a limit in terms of capacity to harvest and market
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demand to the response to changes in extent of reeds. Thus the response is muted, and it
depends on how well used the PD stocks are. There is no longer significant reed use at site
8. The net income or livelihood from household reed harvest is expected to remain relatively
stable in all sites where reeds are harvested except in site 1, where an already well used
resource will decline notably. Elsewhere there will be small increases in household reed
livelihoods at sites 4 and 7. Small decreases may be experienced with the high water use
scenario at sites 5 and 6.
6.1.3
Indicator 3: Household income floodplain grass
Summary of characteristics
Throughout the basin, households harvest thatch grass for use in housing. This takes place
in upland areas and also on river floodplains, where certain, specific, high quality thatch
grass species are also harvested. These wetland floodplain grasses make up indicator 3. It
involves small-scale household-based harvesting of grass using sickles for own use as
specialised construction thatch and very limited marketing. Several species are involved, but
Miscanthus junceus, is representative found on river lower floodplain, river middle floodplain
situations. It depends on regular seasonal floods on floodplains
Used as indicator for Sites 1 to 7 (all sites except 8).
Impact of the Water-use Scenarios
Floodplain grass occurs in two indicator vegetation sites; middle and upper floodplain, and it
is harvested at both. Harvest response is complex and tends to reflect change in the extent
of these stands. Also making it complex is a limit in terms of capacity to harvest and market
demand to the response to changes in extent of floodplain grass. Thus the response is
muted, and it depends on how well used the PD stocks are. There is no longer significant
floodplain grass use at site 8. The net income or livelihood from household floodplain grass
harvest is expected to remain relatively stable in all sites where floodplain grasses are
harvested except in site 1, where an already well used resource will decline notably.
Elsewhere there will be small increases in household floodplain grass livelihoods at sites 4
and 7. Small decreases may be experienced with the high water use scenario at sites 5 and
6.
6.1.4
Indicator 4: Household income floodplain gardens (e.g. molapo)
Summary of characteristics
Households throughout the basin grow crops. In Angola crop production is the most
important source of household income and food earning some 80% of household income.
Here, the sub-humid and humid climate makes it possible to grow most crops in uplands. In
the lower semi-arid parts of the basin the growth of crops is carried out in both uplands and
on floodplains, where additional wetness and fertility enhance yields by some 40%. Crop
production is small-scale in gardens and tillage is limited largely to that by hand or by draft
livestock. Very limited tractor power is available, and mainly in the Namibian and Botswana
parts of the basin. In Namibia and Botswana crop production is of lesser importance for
households because yields are low and losses to wildlife such as elephant can be significant.
Floodplain gardens can be described as small-scale household-based flood-recession crop
production using animal draft power and manual labour, on floodplains for own consumption
as food and very limited marketing and with home milling, complementary to household
upland rain-fed crop production. Representative crops are maize, sorghum, millet,
vegetables. It takes place on river lower floodplain and river middle floodplain sites, and
requires regular seasonal floods on floodplains and regular transitional season 2 to allow
crop growth.
Used as indicator for Sites 3, 4, 7 and 8.
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Impact of the Water-use Scenarios
Floodplain gardens are produced in two indicator vegetation types; lower and middle
floodplain and only at sites 3, 4, 7 and 8. Harvest response is complex and tends to reflect
change in the extent of these habitats. Also making it complex is a limit in terms of capacity
to increase production in response to changes in extent of habitat. Thus the response tends
to be muted. The net income or livelihood from household floodplain gardens is expected to
remain relatively stable in all sites, but will follow the same patterns noted for garden
production. Thus there will be small increases in household floodplain garden livelihoods at
sites 4 and 7. Decreases will be experienced at site 8.
6.1.5
Indicator 5: Household income and wealth - livestock
Summary of characteristics
Livestock are very important for households in the lower basin, providing a range of
household utilities, such as meat, milk, draft power, and store of value. Their value further up
the basin is less, mainly because many households in Angola lack stock, and the money to
buy stock. The indicator involves small-scale household-based open access grazing of
livestock on floodplain, as part of broader upland small-scale livestock keeping for meat milk,
transport and as a store of wealth, with limited marketing. Some 22% of small scale
livestock-keeping value is attributable to use of floodplain grasslands where wetness
enhances production. Local breeds of cattle (Bos indicus) and goats are representative. It
takes place on river middle floodplain and river upper floodplain sites, and depends on
regular seasonal floods on floodplains.
Used as indicator for Sites 3, 4, 6, 7 and 8.
Impact of the Water-use Scenarios
Floodplain grazing takes place in three indicator vegetation types; lower middle and upper
floodplain and only at sites 3, 4, 6, 7 and 8. The grazing production response to scenarios is
complex and tends to reflect change in the extent of these habitats. At sites 4 and 6
production will tend to be stable. At site 7 it is likely to expand significantly with increase in
drier floodplains. At site 8 it would decrease as drier floodplains change to savanna. The net
income or livelihood from household floodplain grazing is expected to remain relatively stable
in sites 4 and 6, but at sites 7 and 8 will follow the same patterns noted for grazing
production. Thus there will be increases in household floodplain grazing livelihoods at site 7
and decreases will be experienced at site 8.
6.1.6
Indicator 6: Household income - tourism
Summary of characteristics
Tourism in the Namibia and Botswana basin areas is overwhelmingly non-consumptive,
nature-based, and focused on wildlife viewing, although some guided recreational fishing and
hunting operations are involved. Medium to large scale lodges and camps with between 10
and 30 beds, serving middle and upper market tourists are most common. Self-drive
camping and guided mobile operations are also present in significant numbers. Nearly all the
value of this tourism is attributable to the presence of the river/wetlands, although the
activities offered can be either land- or water-orientated. Most tourism income for local
households comes through wages and salaries, from full- and part-time employment in local
tourism industry as labour, skilled labour, and occasionally management. To some extent
local households directly provide small-scale services, such as guided canoe trips, to
tourists, supplementing the commercial lodge operations. Representative resources are
general wildlife, including semi aquatic animals, lower, middle, and outer floodplain grazers,
associated predators and birds generally, general scenic habitats and attributes linked to a
mosaic of all the vegetation indicators. It is sited commonly on upper dry banks but making
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use of all vegetation indicators as part of product dependent on dry season low flow and
flood volume, perennial flows in channels, and regular seasonal floods on floodplains
Used as indicator along with indicator 9.1 below for Sites 4, 5, 6, 7 and 8.
Impact of the Water-use Scenarios
Tourism makes use of a complex range of habitats including river banks channels, and
floodplains at sites 4 to 8. It appears to be responsive to changes in dry season low flow,
flood type, and wildlife abundance. The response to scenarios shows a generally sharply
declining trend with increasing water use development upstream. The only exception is in
the central Delta (site 7). In site 4 the high scenario gives higher numbers than is better than
the medium scenario but both are lower than present day. Site 8 shows complete elimination
of tourism with high scenario. The net income or household livelihoods from tourism shows
the same trends as for tourism numbers, but the changes are not as extreme. This because
the household income is made up of wages and salaries, which are less sensitive than other
income such as profits.
6.1.7
Indicator 7: Potable water/water quality
Summary of characteristics
Potable water/water quality was identified as an indicator which might affect household
wellbeing in the basin. It entails small-scale household-based use of river water for
household needs. The valuation of water use has been carried out separately as part of the
valuation of water supply in the analysis of water development scenarios. It also forms part
of the indirect use values as a function of the ecosystem water purification function. The
general water quality indicators are representative. Small scale water extraction mostly takes
place from channels, floodplains during floods, and residual floodplain pools. It relies on
perennial flows in channels, good water quality.
Used as indicator for all Sites but not valued.
Impact of the Water-use Scenarios
Potable water quality, as a measure of dissatisfaction (non-wellbeing), was not valued, and
the impact on this from scenarios was only assessed subjectively in terms of percentage of
PD (present day). At most sites a small increase was predicted, while at site 8, drying of
channels would result in significant increase in negative effects increasing with scenario. A
moderate impact would be seen at site 1 with all scenarios, and at sites 5 and 6 a moderate
impact would be seen with high scenario.
6.1.8
Indicator 8: Wellbeing/welfare from intangibles
Summary of characteristics
It was recognised that while households in the basin derive welfare from income from
indicators 1 to 7, above, they can also also benefit from general individual, household and
community feeling on ecosystem integrity in the face of flow change. Thus, an indicator to
capture the benefits of indicators 1 to 7 together as well as overall ecosystem integrity was
recognised. It is related to channels, floodplains, and all habitats associated with ecosystem
integrity, and among other things it requires perennial flows in channels, regular seasonal
floods on floodplains.
Used as indicator for all Sites but not valued.
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Impact of the Water-use Scenarios
Household and community wellbeing from intangibles was not valued but assessed in terms
of percentage deviation for PD (present day). It is intended to reflect household perception of
ecosystem integrity. The response to scenarios shows a generally declining trend with
increasing water use development upstream. Declines are mostly small, but greater in site 8
and site 1, where effects on flow and flooding may be most noticeable.
6.1.9
Indicator 9.1: Macro-effects from tourism income, excluding household
income (including multipliers)
Summary of characteristics
Tourism in the Namibia and Botswana basin areas is overwhelmingly non-consumptive,
nature-based, and focused on wildlife viewing, although some guided recreational fishing and
hunting operations are involved. Medium to large scale lodges and camps with between 10
and 30 beds, serving middle and upper market tourists are most common. Self-drive
camping and guided mobile operations are also present in significant numbers. Nearly all the
value of this tourism is attributable to the presence of the river/wetlands, although the
activities offered can be either land- or water-orientated. Indicator 6, above, deals specifically
with tourism income for local households comes through wages and salaries and
occasionally services. This indicator deals with the income received by the other
stakeholders in tourism investments - the owners of capital, government and entrepreneurs.
Representative resources are general wildlife, including semi aquatic animals, lower, middle,
and outer floodplain grazers, associated predators and birds generally, general scenic
habitats and attributes linked to a mosaic of all the vegetation indicators. It is sited commonly
on upper dry banks but making use of all vegetation indicators as part of product
dependent on dry season low flow and flood volume, perennial flows in channels, and regular
seasonal floods on floodplains
Used as indicator along with indicator 6 above, for Sites 4, 5, 6, 7 and 8.
Impact of the Water-use Scenarios
The contribution to the national income from tourism shows the same trends as for tourism
numbers and livelihoods, but the changes are less extreme at site 4 and much more extreme
at the other sites. In particular at sites 5, 6, and 8 the short term impacts of the high scenario
are major economic losses. This will in the longer term result in a much reduced tourism
industry in the basin. The medium scenario will have a similar impact, but not as large. It is
predicted that overall there will be a moderate decline for the low scenario and a drastic
decline for the macro-economic contribution of tourism with the medium and high scenarios.
This will not affect sites 1 to 7 since there is no tourism there.
6.1.10
Indicator 9.2: Macro-effects from household income 1-6, (including
multipliers, etc)
Summary of characteristics
The small-scale use natural resources under indicators 1 to 6 provide net incomes
contributing to livelihoods and they also contribute other income to the economies through
linkages and multiplier effects. This indicator is to capture this additional income. It is thus
based on all small-scale household-based activities described under indicators 1 to 6. All
species, ecosystems, attributes listed under indicators 1 to 6 are representative, as well as all
locations described under these. It requires perennial flows in channels and regular
seasonal floods on floodplains
Used as indicator for all Sites (1 to 8) and measured along with each indicator, 1 to 6.
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Impact of the Water-use Scenarios
The contribution to national income (economic contribution) of household fishing tends, along
with catch and net income, to peak during floods in areas with floodplains. In areas without
floodplains economic contribution is more stable. Generally the scenarios will progressively
reduce economic contribution. In the lower basin the high scenario will severely reduce fish
economic contribution.
The pattern for the contribution of household reed harvest to national income is very similar
to that for livelihoods (indicator 2). The contribution is expected to remain relatively stable in
all sites where reeds are harvested except in site 1, where an already well used resource will
decline notably. Elsewhere there will be small increases in reed economic contribution at
sites 4 and 7. Small decreases may be experienced with the high water use scenario at sites
5 and 6.
The pattern for the contribution of household floodplain grass harvest to national income is
very similar to that for livelihoods (indicator 3). The contribution is expected to remain
relatively stable in all sites where floodplain grasses are harvested except in site 1, where an
already well used resource will decline notably. Elsewhere there will be small increases in
floodplain grass economic contribution at sites 4 and 7. Small decreases may be
experienced with the high water use scenario at sites 5 and 6.
The pattern for the contribution of household floodplain gardens to national income is very
similar to that for livelihoods (indicator 4). It is expected to remain relatively stable in all sites,
but will follow the same patterns noted for garden production. Thus there will be small
increases in household floodplain garden livelihoods at sites 4 and 7. Decreases will be
experienced at sites 8. The medium and high scenarios will actually result in economic
losses in the short term.
The pattern for the contribution of household floodplain grazing to national income is very
similar to that for livelihoods (indicator 5). It is expected to remain relatively stable in sites 4
and 6, but will increase significantly in site 7 and will decrease to result in a short term
economic loss in site 8.
It is predicted that overall there will be moderate declines in the economic contribution of the
rural household sectors in the basin with the low medium and high scenarios. The response
will tend to be muted by increases in some resources.
6.1.11
Indicator 9.3: Indirect use
Summary of characteristics
This indicator embraces indirect use values, i.e., off-site local, national, regional, or global
use values associated with river-based ecosystem services, including carbon sequestration,
wildlife refuge, groundwater recharge, flood attenuation, scientific and educational value,
among others etc. It is only studied for the Botswana basin, and is generally poorly studied.
It is represented by general ecosystem integrity, providing the range of ecosystem services
referred to above. It has no specific location but is associated with a range of geo-
morphological and ecological features, including vegetation and wildlife, which affect
seasonal flooding patterns, as well as perennial nature of flow. Generally it requires
perennial flows in channels, and regular seasonal floods on floodplains.
Used as indicator for all Sites (1 to 8) but not measured and not valued for response.
Impact of the Water-use Scenarios
Effects of scenarios on indirect use values were not valued for lack of data, but were
subjectively assigned impacts in terms of percentage change from PD (present day). These
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showed quite significant progressive declines with increasing water use. These were most
noticeable with site 1 and site 8.
6.1.12
Indicator 9.4: Non-use
Summary of characteristics
This indicator embraces existence, bequest, and option values for preservation, manifested
as local, national, regional and global willingness to pay for preservation of resources in the
river system. The values are poorly researched and only small amounts of data are available
for Botswana. It is represented broadly including general wildlife, including semi aquatic
animals, lower, middle, and outer floodplain grazers, associated predators and birds
generally, general scenic habitats and attributes linked to a mosaic of all the vegetation
indicators. It also embraces the broader ecosystem and its integrity, including all the
vegetation and wildlife indicators, mostly in the better known lower parts of the basin
(Okavango delta). It depends on perennial flows in channels, regular seasonal floods on
floodplains.
Used as indicator for all Sites (1 to 8) but not measured and not valued for response.
Impact of the Water-use Scenarios
Effects of scenarios on non-use values were not valued for lack of data, but were subjectively
assigned impacts in terms of percentage change from PD (present day). Here again the
effects on ecosystem integrity were considered key. The assessment showed quite
significant progressive declines with increasing water use. These were most noticeable with
site 1 and site 8.
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7. Conclusions
Scenarios describe the impacts of the specific developments that were chosen for
consideration, and any other permutation making up a particular level of development (low,
medium or high in this case) would not necessarily have the described impacts. A different
arrangement of proposed water-resource schemes could produce different impacts. Altering
the development placed in the hydrological model upstream of Capico, for instance, so that
more water would continue to flow down the river in the dry season, could greatly reduce the
predicted impact at that site. This highlights the value of the DSS, which has been set up to
be queried, and to provide predictions of the impact of, any permutation of possible
developments.
In this project, the EFlow Assessment was preliminary, based on available information, and
the predictions are thus of low confidence. It sets the scene for a Phase 2 research-based
EFlow Assessment, where major data gaps can be addressed, models improved, more
scenarios and sites investigated, and higher-confidence predictions produced. Such a Phase
2 would also incorporate an improved DSS with indicators linked in series to better show the
domino effect of changing flows through hydraulic and water-quality changes, to impacts on
the vegetation, then the fauna, then people.
The EF Scenarios focused on changes that were considered likely through potential changes
in flow patterns. Impacts of constructing and operating water-resource infrastructure were
not addressed, nor were knock-on effects such as increased agricultural return flows
potentially laden with pesticide residues and fertilisers. Another aspect not addressed
because of the lack of data and models, yet vitally important, is the sediment dynamics of the
system and how flow changes and in-channel dams could change the movement of
sediments through the system and thus the character of the channels, floodplains and delta.
Social aspects are also not addressed fully in the EFlow assessment. For example, changes
in human population over time were not included, adaptations to flow pattern change and its
effects over the medium and long terms were not included, and longer term changes in
demand for products were also not included. The further interpretation and aggregation of
the EFlow assessment social results for the TDA has to some extent addressed these
issues.
The potential water-resource developments included revealed that the biophysical impacts
would generally increase with distance downstream and therefore be greatest at the
downstream end of the basin. The medium scenario would present some risk of severe
degradation at some points in the basin, and the high scenario would greatly increase this
risk and its potential area of impact. Overall, the low and medium scenarios would produce
predominately in-country impacts whilst the high scenario impacts would tend to be more far-
reaching and transboundary.
The majority, but by no means all, of the biophysical impacts, are predicted to stay within the
natural range of variability of the system, but to increasingly compress this variability,
decreasing the number of `good' years when animal and plant abundances are high and
increasing the number of `bad' years when abundances are very low. The whole ecosystem
would thus be gradually pushed into more prolonged stress, with habitats, species and
perhaps even whole communities of plants and animals declining and some disappearing.
Impacts on people through changes in river basin livelihoods and changes in national income
in the basin countries are predicted to be drastic and markedly more so with distance
downstream. This is primarily because of the severely negative impact that the development
scenarios will have on the tourism industry which makes up by far the majority of the income
generated by the river ecosystem. The medium and high water use development scenarios
will in particular have a devastating impact on this income. Impacts on household income
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E-Flows Ecological and Social Predictions Scenario Report
from river/wetland based natural resource use are also predicted to decline. This is primarily
because households rely on the tourism industry for a significant amount of their river-related
income. Use of the river and wetland system for fish, reeds, grass, crops and grazing, will
decline overall but some, relatively minor, uses are predicted to benefit and increase with the
scenarios.
The response curves leading to the finding that water use impact would be drastic for tourism
are based partly on the results of a small research project carried out in Botswana, as part of
the EFlow Assessment. This was a small survey in the local tourism industry assessing likely
impacts of flow change and its biophysical consequences on tourism. Given the significance
of a massive impact on tourism, it is imperative that a Phase 2 research-based EFlow
Assessment should include further more in-depth research into flow change and tourism in
the basin.
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8. References
Adamson, P. 2006. Hydrological background and the generation of exploratory flow regimes
for the development of the impact analysis tools. Integrated Basin Flow
Management. Internal Report of the Mekong River Commission, Laos PDR.
45 pp.
Brown, C.A. and Joubert, A.R. 2003. Using multicriteria analysis to develop environmental
flow scenarios for rivers targeted for water-resource development. Water SA
Vol. 29 (No. 4).
Department of Water Affairs and Forestry. 1999. Resource Directed Measures for the
Protection of Water Resources. Version 1.0. Pretoria, South Africa.
Dollar, E.S.J., Brown, C.A., Turpie, J.K., Joubert, A.R., Nicolson, C.R. and Manyaka, S.M.
2006: The development of the Water Resource Classification System
(WRCS). Volume 1. Overview and 7-step classification procedure. CSIR
Report No., Department of Water Affairs and Forestry, Pretoria, 70pp.
Dollar, E.S.J, Nicolson, C.R., Brown, C.A., Turpie, J.K., Joubert, A.R, Turton, A.R., Grobler,
D.F. and Manyaka, S.M. In press. The development of the South African
Water Resource Classification System (WRCS): a tool towards the
sustainable, equitable and efficient use of water resources in a developing
country. Water Policy..
King, J.M., Brown, C.A. and Sabet, H. 2003. A scenario-based holistic approach to
environmental flow assessments for regulated rivers. Rivers Research and
Applications 19 (5-6). Pg 619-640.
Kleynhans, C.J. 1996. A qualitative procedure for the assessment of the habitat integrity
status of the Luvuvhu River. Journal of Aquatic Ecosystem Health 5: 41 - 54.
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The Okavango River Basin Transboundary Diagnostic Analysis Technical Reports
In 1994, the three riparian countries of the
Analysis to establish a base of available scientific
Okavango River Basin Angola, Botswana and
evidence to guide future decision making. The
Namibia agreed to plan for collaborative
study, created from inputs from multi-disciplinary
management of the natural resources of the
teams in each country, with specialists in hydrology,
Okavango, forming the Permanent Okavango River
hydraulics, channel form, water quality, vegetation,
Basin Water Commission (OKACOM). In 2003, with
aquatic invertebrates, fish, birds, river-dependent
funding from the Global Environment Facility,
terrestrial wildlife, resource economics and socio-
OKACOM launched the Environmental Protection
cultural issues, was coordinated and managed by a
and Sustainable Management of the Okavango
group of specialists from the southern African region
River Basin (EPSMO) Project to coordinate
in 2008 and 2009.
development and to anticipate and address threats
to the river and the associated communities and
The following specialist technical reports were
environment. Implemented by the United Nations
produced as part of this process and form
Development Program and executed by the United
substantive background content for the Okavango
Nations Food and Agriculture Organization, the
River Basin Transboundary Diagnostic Analysis.
project produced the Transboundary Diagnostic
Final Study
Reports integrating findings from all country and background reports, and covering the entire
Reports
basin.
Aylward, B.
Economic Valuation of Basin Resources: Final Report to
EPSMO Project of the UN Food & Agriculture Organization as
an Input to the Okavango River Basin Transboundary
Diagnostic Analysis
Barnes, J. et al.
Okavango River Basin Transboundary Diagnostic Analysis:
Socio-Economic Assessment Final Report
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment Project
C.A.
Initiation Report (Report No: 01/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment EFA
C.A.
Process Report (Report No: 02/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Guidelines for Data Collection, Analysis and Scenario Creation
(Report No: 03/2009)
Bethune,
S.
Mazvimavi,
Okavango River Basin Environmental Flow Assessment
D. and Quintino, M.
Delineation Report (Report No: 04/2009)
Beuster, H.
Okavango River Basin Environmental Flow Assessment
Hydrology Report: Data And Models(Report No: 05/2009)
Beuster,
H. Okavango River Basin Environmental Flow Assessment
Scenario Report : Hydrology (Report No: 06/2009)
Jones, M.J.
The Groundwater Hydrology of The Okavango Basin (FAO
Internal Report, April 2010)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 1
of 4)(Report No. 07/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 2
of 4: Indicator results) (Report No. 07/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions: Climate
Change Scenarios (Volume 3 of 4) (Report No. 07/2009)
King, J., Brown, C.A.,
Okavango River Basin Environmental Flow Assessment
Joubert, A.R. and
Scenario Report: Biophysical Predictions (Volume 4 of 4:
Barnes, J.
Climate Change Indicator Results) (Report No: 07/2009)
King, J., Brown, C.A.
Okavango River Basin Environmental Flow Assessment Project
and Barnes, J.
Final Report (Report No: 08/2009)
Malzbender, D.
Environmental Protection And Sustainable Management Of The
Okavango River Basin (EPSMO): Governance Review
Vanderpost, C. and
Database and GIS design for an expanded Okavango Basin
Dhliwayo, M.
Information System (OBIS)
Veríssimo, Luis
GIS Database for the Environment Protection and Sustainable
Management of the Okavango River Basin Project
Wolski,
P.
Assessment of hydrological effects of climate change in the
Okavango Basin
Country Reports
Angola
Andrade e Sousa,
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Biophysical Series
Helder André de
Okavango: Módulo do Caudal Ambiental: Relatório do
101
E-Flows Ecological and Social Predictions Scenario Report
Especialista: País: Angola: Disciplina: Sedimentologia &
Geomorfologia
Gomes, Amândio
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Vegetação
Gomes,
Amândio
Análise Técnica, Biofísica e Socio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final:Vegetação da Parte Angolana da Bacia Hidrográfica Do
Rio Cubango
Livramento, Filomena
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina:Macroinvertebrados
Miguel, Gabriel Luís
Análise Técnica, Biofísica E Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango:
Subsídio Para o Conhecimento Hidrogeológico
Relatório de Hidrogeologia
Morais, Miguel
Análise Diagnóstica Transfronteiriça da Bacia do Análise Rio
Cubango (Okavango): Módulo da Avaliação do Caudal
Ambiental: Relatório do Especialista País: Angola Disciplina:
Ictiofauna
Morais,
Miguel
Análise Técnica, Biófisica e Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final: Peixes e Pesca Fluvial da Bacia do Okavango em Angola
Pereira, Maria João
Qualidade da Água, no Lado Angolano da Bacia Hidrográfica
do Rio Cubango
Santos,
Carmen
Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S. N.
Okavango: Módulo do Caudal Ambiental: Relatório de
Especialidade: Angola: Vida Selvagem
Santos, Carmen Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S.N.
Okavango:Módulo Avaliação do Caudal Ambiental: Relatório de
Especialidade: Angola: Aves
Botswana Bonyongo, M.C.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Wildlife
Hancock, P.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report: Country:
Botswana: Discipline: Birds
Mosepele,
K. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Fish
Mosepele, B. and
Okavango River Basin Technical Diagnostic Analysis:
Dallas, Helen
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Aquatic Macro Invertebrates
Namibia
Collin Christian &
Okavango River Basin: Transboundary Diagnostic Analysis
Associates CC
Project: Environmental Flow Assessment Module:
Geomorphology
Curtis, B.A.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report Country:
Namibia Discipline: Vegetation
Bethune, S.
Environmental Protection and Sustainable Management of the
Okavango River Basin (EPSMO): Transboundary Diagnostic
Analysis: Basin Ecosystems Report
Nakanwe, S.N.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Aquatic Macro Invertebrates
Paxton,
M. Okavango River Basin Transboundary Diagnostic Analysis:
Environmental Flow Module: Specialist
Report:Country:Namibia: Discipline: Birds (Avifauna)
Roberts, K.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Wildlife
Waal,
B.V. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia:Discipline: Fish Life
Country Reports
Angola
Gomes, Joaquim
Análise Técnica dos Aspectos Relacionados com o Potencial
Socioeconomic
Duarte
de Irrigação no Lado Angolano da Bacia Hidrográfica do Rio
Series
Cubango: Relatório Final
Mendelsohn,
.J.
Land use in Kavango: Past, Present and Future
Pereira, Maria João
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Qualidade da Água
Saraiva, Rute et al.
Diagnóstico Transfronteiriço Bacia do Okavango: Análise
Socioeconómica Angola
Botswana Chimbari, M. and
Okavango River Basin Trans-Boundary Diagnostic Assessment
102
E-Flows Ecological and Social Predictions Scenario Report
Magole, Lapologang
(TDA): Botswana Component: Partial Report: Key Public Health
Issues in the Okavango Basin, Botswana
Magole,
Lapologang
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Land Use Planning
Magole, Lapologang
Transboundary Diagnostic Analysis (TDA) of the Botswana p
Portion of the Okavango River Basin: Stakeholder Involvement
in the ODMP and its Relevance to the TDA Process
Masamba,
W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Output 4: Water Supply and
Sanitation
Masamba,W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Irrigation Development
Mbaiwa.J.E. Transboundary Diagnostic Analysis of the Okavango River
Basin: the Status of Tourism Development in the Okavango
Delta: Botswana
Mbaiwa.J.E. &
Assessing the Impact of Climate Change on Tourism Activities
Mmopelwa, G.
and their Economic Benefits in the Okavango Delta
Mmopelwa,
G.
Okavango River Basin Trans-boundary Diagnostic Assessment:
Botswana Component: Output 5: Socio-Economic Profile
Ngwenya, B.N.
Final Report: A Socio-Economic Profile of River Resources and
HIV and AIDS in the Okavango Basin: Botswana
Vanderpost,
C.
Assessment of Existing Social Services and Projected Growth
in the Context of the Transboundary Diagnostic Analysis of the
Botswana Portion of the Okavango River Basin
Namibia
Barnes, J and
Okavango River Basin Technical Diagnostic Analysis:
Wamunyima, D
Environmental Flow Module: Specialist Report:
Country: Namibia: Discipline: Socio-economics
Collin Christian &
Technical Report on Hydro-electric Power Development in the
Associates CC
Namibian Section of the Okavango River Basin
Liebenberg, J.P.
Technical Report on Irrigation Development in the Namibia
Section of the Okavango River Basin
Ortmann, Cynthia L.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report Country:
Namibia: discipline: Water Quality
Nashipili,
Okavango River Basin Technical Diagnostic Analysis: Specialist
Ndinomwaameni
Report: Country: Namibia: Discipline: Water Supply and
Sanitation
Paxton,
C.
Transboundary Diagnostic Analysis: Specialist Report:
Discipline: Water Quality Requirements For Human Health in
the Okavango River Basin: Country: Namibia
103
E-Flows Ecological and Social Predictions Scenario Report
104