Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module
Specialist Report
Country: Botswana
Discipline: Wildlife
M.C. Bonyongo
June 2009
1
EFA Botswana Wildlife
Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module
Specialist Report
Country: Botswana
Discipline: Wildlife
Author: M.C. Bonyongo
Date: June 2009
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EFA Botswana Wildlife
EXECUTIVE SUMMARY
The Okavango Delta supports a high diversity of wildlife ranging from those that are almost
totally aquatic or semi-aquatic to animals completely independent of water except for drinking
purposes. Animals of the Okavango Delta are linked to flows to a varying degree. This study
set to assess and analyse potential responses of wildlife to selected flow categories which
could be brought by development scenarios that affect flow variations within the Okavango
River Basin. The study identified five key groups of wildlife indicators namely semi-aquatic
species, frogs and river snakes, lower floodplain grazers, middle/upper floodplain grazers
and outer floodplain grazers. Semi aquatic and aquatic species are likely to respond to flow
variation immediately, especially the decline in flows which may lead to drastic reduction in
water levels. On the contrary floodplain grazers, especially those that utilise the lower and
upper floodplains would benefit from a reduce flow which leads to less or short duration of
flooding. On the hand, floodplain grazers would be negatively affected by a major increase
in flows especially when such a flow would lead extended long duration flooding. Under such
circumstances, seasonally flooded areas would be flooded longer than usual, resulting in
reduced access to grazing resources which normally became available when floods recede.
The outer floodplain grazers which are predominately terrestrial species that do not depend
on water except for drinking, are unlikely to be negatively affected by immediately respond to
variation in flows.
Literature revealed that seasonal flooding is the driving force behind the functioning of
floodplain ecosystems in the Okavango Delta, resulting in seasonal shrinking and swelling of
grazing resources as a result of seasonal flooding and receding of the floodplains. It is this
seasonal variability in forage quality and quantity which makes the Okavango Delta a unique
ecosystem. The dynamic forage resources, which may be limiting at certain times of the
year, influence the community ecology of large grazers of the Okavango Delta. When water
level changes with the flooding dynamics, species concentrate on high grounds or disperse
onto the floodplains, the population densities of these species change. When the water level
recedes from August - September, large terrestrial ungulates move in to feed on the grasses
that established or resprouted in this zone, which is a reliable grazing resource during the dry
season.
The study was challenged by lack of data to support arguments concerning potential
response of different wildlife to changes in flows. Long term ecological monitoring data, and
data that link different wildlife to flows, are essential in order improve predictions of wildlife
potential response to flow variations. Although challenged by lack of empirical evidence, the
study benefited from the specialist's existing knowledge of the system. The study provides a
useful baseline that can be used for further in-depth analyses of the relationship between
wildlife and flows which is key in the prediction of the response of different indictors to flow
variation.
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EFA Botswana Wildlife
TABLE OF CONTENTS
EXECUTIVE SUMMARY .......................................................................................................... 3
LIST OF TABLES ..................................................................................................................... 5
LIST OF FIGURES ................................................................................................................... 6
ABBREVIATIONS .................................................................................................................... 7
ACKNOWLEDGEMENTS ........................................................................................................ 7
1.INTRODUCTION ................................................................................................................... 8
1.1
Background ................................................................................................................ 8
1.2
Okavango River Basin EFA Objectives and Workplan .............................................. 8
1.2.1
Project objectives ................................................................................................ 8
1.3
Layout of this report ................................................................................................... 9
2.STUDY AREA ..................................................................................................................... 10
2.1
Description of the Okavango Basin .......................................................................... 10
2.2
Delineation of the Okavango Basin into Integrated Units of Analysis ...................... 11
2.3
Overview of sites ...................................................................................................... 12
2.4
Discipline-specific description of (Botswana) sites .................................................. 13
3.IDENTIFICATION OF INDICATORS AND FLOW CATEGORIES ...................................... 16
3.1
Indicators ................................................................................................................. 16
3.1.1
Introduction ....................................................................................................... 16
3.2
Indicator list for Wildlife ............................................................................................ 16
3.3
Description and location of indicators ...................................................................... 17
3.4
Flow categories river sites .................................................................................... 19
3.5
Inundation categories delta sites .......................................................................... 23
4.LITERATURE REVIEW ....................................................................................................... 24
4.1
Introduction .............................................................................................................. 24
4.2
Indicator 1: Semi-aquatic ......................................................................................... 25
4.2.1
Main characteristics of Indicator 1 .................................................................... 25
4.2.2
Main characteristics of Indicator 2 Frogs and River snakes .......................... 27
4.2.3 Main characteristics of Indicator 3: ........................................................................ 27
4.2.4 Main characteristics of Indicator 4 Outer/tertiary floodplain grazers ...................... 28
4.2.5
Main characteristics of Indicator 5: Lower floodplain areas .............................. 29
5.DATA COLLECTION AND ANALYSIS ................................................................................ 31
5.1
Methods for data collection and analysis ................................................................. 31
5.2
Results ..................................................................................................................... 31
5.3
A summary of present understanding of the predicted responses of all wildlife
indicators to potential changes in the flow regime .............................................................. 32
5.3.1
Indicator (Semi aquatic) .................................................................................... 33
5.3.2
Indicator 2 (Frogs, River snakes) ...................................................................... 34
5.3.3
Indicator 3 (Middle Floodplain Grazers) ............................................................ 35
5.3.4
Indicator 4 (Outer floodplains) .......................................................................... 36
5.3.4
Indicator 5 (Lower floodplain grazers) .............................................................. 37
5.4
Conclusion ............................................................................................................... 38
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EFA Botswana Wildlife
6.REFERENCES ........................................................................................................... 39
APPENDIX A: FULL DESCRIPTIONS OF INDICATORS ............................................. 41
LIST OF TABLES
Table 2. 1: Location of the eight EFA sites .................................................................... 12
Table 3. 1: List of indicators for Wildlife and those chosen to represent each site ........ 16
Table 3. 2: Questions to be addressed at the Knowledge Capture Workshop, per indicator
per site. In all cases, 'natural' embraces the full range of natural
variability .................................................................................. 22
Table 3. 3: Inundation categories for the Okavango as recognised by the HOORC
inundation model ...................................................................... 23
Table 4. 1: Table showing the semi-aquatic indicator species ...................................... 26
Table 4. 2: Table showing terrestial grazers which utilise seasonal floodplains ........... 28
Table 4. 3: Outer floodplain grazers which do not depend on water except for drinking29
Table 4. 4: Table showing floodplain grazers ................................................................ 29
Table 5. 1 Predicted responce to possible changes in the flow regime of Semi Aguatic
species in the Okavango River Ecosystem .............................. 33
Table 5. 2: Predicted responce to possible changes in the flow regime of Frogs, River
Snakes in the Okavango River Ecosystem .............................. 34
Table 5. 3: Predicted response to possible changes in the flow regime of Middle
Floodplain Grazers in the Okavango River Ecosystem ............ 35
Table 5. 4: Predicted response to possible changes in the flow regime of Outer floodplain
grazers in the Okavango River Ecosystem .............................. 36
Table 5. 5: Predicted response to possible in the flow regime of Lower floodplain grazers
in the Okavango River Ecosystem ........................................... 37
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EFA Botswana Wildlife
LIST OF FIGURES
Figure 2. 1: Upper Okavango River Basin from sources to the norther end of the Delta10
Figure 2. 2: The Okavango River Basin, showing drainage into the Okavango Delta and
the Makgadikgadi Pans ............................................................ 11
Figure 2. 3: Map of the Okavango Delta showing division into zones ........................... 13
Figure 2. 4: A photo showing Okavango River meandering through permanent swamps in
the Panhandle .......................................................................... 14
Figure 2. 5: Picture of seasonally flooded floodplains during peak floods ..................... 14
Figure 2. 6: Picture of occasionally flooded areas found in the Xakanaxa area and other
parts of the Delta ...................................................................... 15
Figure 3. 1 Three representative years for Site 1: Cuebe River @ Capico, illustrating the
approximate division of the flow regime into four flow seasons 20
Figure 3. 2 Three representative years for Site 2: Cubango River @ Mucindi, illustrating
the approximate division of the flow regime into four flow seasons
................................................................................................. 20
Figure 3. 3 Three representative years for Site 3: Cuito River@ Cuito Cuanavale,
illustrating the approximate division of the flow regime into four
flow seasons ............................................................................ 21
Figure 3. 4 Three representative years for Site 4: Okavango River@ Kapoka
(hydrological data from Rundu) illustrating the approximate
division of the flow regime into four flow seasons .................... 21
Figure 3. 5 Three representative years for Site 5: Okavango river @ Popa (hydrological
data from Mukwe), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 22
Figure 4. 1 A 10 year moving average of inflow at Mohembo from 1933 to 2005. Source
(Bonyongo and Ugutu 2009: unpublished manuscript ............. 25
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EFA Botswana Wildlife
ABBREVIATIONS
ABBREVIATION
MEANING
HOORC
Harry Oppenheimer Okavango Research Centre
ACKNOWLEDGEMENTS
Firstly, I would like to thank my colleague, brother, friend and mentor Prof Mazvimavi for
introducing the concept of Environmental Flows Assessment to me and colleagues at the
Harry Oppenheimer Okavango Research Centre (HOORC). I would like to sincerely express
my sincere gratitude to all members of the Southern Waters Team particular Jackie King for
her patience, tolerance and understanding. I would like to appreciate colleagues from Angola
in Kevin and Carmen for maintaining email contact through out the whole project. Not
forgetting the Botswana Team members for their cooperation. Lastly I would like to thank the
Directorate of HOORC and Deputy Vice Chancellor for granting HOORC staff members to
partake in this noble undertaking.
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EFA Botswana Wildlife
1. INTRODUCTION
1.1
Background
An Environmental Protection and Sustainable Management of the Okavango River Basin
(EPSMO) Project is being implemented under the auspices of the Food and Agriculture
Organization of the United Nations (UN-FAO). One of the activities is to complete a
transboundary diagnostic assessment (TDA) for the purpose of developing a Strategic Action
Plan for the basin. The TDA is an analysis of current and future possible causes of
transboundary issues between the three countries of the basin: Angola, Namibia and
Botswana. The Okavango Basin Steering Committee (OBSC) of the Okavango River Basin
Water Commission (OKACOM) noted during a March 2008 meeting in Windhoek, Namibia,
that future transboundary issues within the Okavango River basin are likely to occur due to
developments that would modify flow regimes. The OBSC also noted that there was
inadequate information about the physico-chemical, ecological and socioeconomic effects of
such possible developments. OBSC recommended at this meeting that an Environmental
Flow Assessment (EFA) be carried out to predict possible development-driven changes in
the flow regime of the Okavango River system, the related ecosystem changes, and the
consequent impacts on people using the river's resources.
The EFA is a joint project of EPSMO and the Biokavango Project. One part of the EFA is a
series of country-specific specialist studies, of which this is the Wildlife report for Botswana.
1.2
Okavango River Basin EFA Objectives and Workplan
1.2.1
Project objectives
The goals of the EFA are:
·
to summarise all relevant information on the Okavango River system and its
users, and collect new data as appropriate within the constraints of the EFA
·
to use these to provide scenarios of possible development pathways into the
future for consideration by decision makers, enabling them to discuss and
negotiate on sustainable development of the Okavango River Basin;
·
to include in each scenario the major positive and negative ecological, resource-
economic and social impacts of the relevant developments;
·
to complete this suite of activities as a pilot EFA, due to time constraints, as input
to the TDA and to a future comprehensive EFA.
The specific objectives are:
·
to ascertain at different points along the Okavango River system, including the
Delta, the existing relationships between the flow regime and the ecological
nature and functioning of the river ecosystem;
·
to ascertain the existing relationships between the river ecosystem and peoples'
livelihoods;
·
to predict possible development-driven changes to the flow regime and thus to
the river ecosystem;
·
to predict the impacts of such river ecosystem changes on people's livelihoods.
·
to use the EFA outputs to enhance biodiversity management of the Delta.
·
to develop skills for conducting EFAs in Angola, Botswana, and Namibia.
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EFA Botswana Wildlife
1.3
Layout of this report
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EFA Botswana Wildlife
2. STUDY
AREA
2.1
Description of the Okavango Basin
The Okavango River Basin consists of the areas drained by the Cubango, Cutato, Cuchi,
Cuelei, Cuebe, and Cuito rivers in Angola, the Okavango River in Namibia and Botswana,
and the Okavango Delta (Figure 2.1). This basin topographically includes the area that was
drained by the now fossil Omatako River in Namibia. Outflows from the Okavango Delta are
drained through the Thamalakane and then Boteti Rivers, the latter eventually joining the
Makgadikgadi Pans. The Nata River, which drains the western part of Zimbabwe, also joins
the Makgadikgadi Pans. On the basis of topography, the Okavango River Basin thus
includes the Makgadikgadi Pans and Nata River Basin (Figure 2.2). This study, however,
focuses on the parts of the basin in Angola and Namibia, and the Panhandle/Delta/Boteti
River complex in Botswana. The Makgadikgadi Pans and Nata River are not included.
Upper Okavango River Basin
N
W
E
S
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Major settlement
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River
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#
ue
Fossil river
be
C
Panhandle
ANGOLA
uiri
Permanent swamps
ri
#
Seasonal swamps
Cubango
Cuito
NAMIBIA
Okavango
#
Rundu
#
#
#
0
300 Kilometers
#
Figure 2. 1: Upper Okavango River Basin from sources to the norther end of the Delta
10
EFA Botswana Wildlife
Okavango River Basin
N
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ta
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to
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ANGOLA
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NAMIBIA
Okavango
#
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Maun
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Makgadikgadi Pans
# Ghanzi
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Major settlement
River
Fossil river
Panhandle
0
600 Kilometers
Permanent swamps
Seasonal swamps
Figure 2. 2: The Okavango River Basin, showing drainage into the Okavango Delta and the
Makgadikgadi Pans
2.2
Delineation of the Okavango Basin into Integrated Units of Analysis
Within the Okavango River Basin, no study could address every kilometre stretch of the river,
or every person living within the area. Instead, representative areas that are reasonably
homogeneous in character may be delineated and used to representative much wider areas,
and then one or more representative sites chosen in each as the focus for data-collection
activities. The results from each representative site can then be extrapolated over the
respective wider areas.
Using this approach, the Basin was delineated into Integrated Units of Analysis
(EPSMO/Biokavango Report Number 2; Delineation Report) by:
dividing the river into relatively homogeneous longitudinal zones in terms of:
hydrology;
geomorphology;
water chemistry;
fish;
aquatic invertebrates;
vegetation;
harmonising the results from each discipline into one set of biophysical river zones;
11
EFA Botswana Wildlife
dividing the basin into relatively homogeneous areas in terms of social systems;
harmonising the biophysical river zones and the social areas into one set of Integrated
Units of Analysis (IUAs).
The 19 recognised IUAs were then considered by each national team as candidates for the
location of the allocated number of study sites:
Angola: three
sites
Namibia: two
sites
Botswana: three sites.
The sites chosen by the national teams are given in Table 2.1.
Country River
Location
EFA Site No
Panhandle at
6 Botswana
Okavango
Shakawe
7
Botswana
Khwaei
Xakanaka in Delta
8 Botswana
Boteti Chanoga
Table 2. 1: Location of the eight EFA sites
2.3 Overview
of
sites
The Okavango Delta was delineated on the basis of the duration and frequency of
inundation, and the responses of the parts of the Delta to inflow from upstream and local
rainfall. Thus the Delta can be divided into areas that are permanently flooded, seasonally
flooded, occasionally flooded, and drylands. In addition the presence of channels and
floodplains was also used for delineating the delta.
Zonation
The Okavango Delta was divided into the following five zones
i.
Panhandle which stretches from Mohembo to the northern limits of the alluvial fan,
ii.
Eastern zone fed by flows of the Nqoga River into the Maunchira which the splits into
Mboroga and Khwai Rivers.
iii.
Central zone mainly fed by flows of the Jao-Boro including the Boro and Xudum
distributaries
iv.
Western zone with the Thaoge River.
v.
Outflow zone with the Thamalakane-Boteti River up to Chanoga.
The eastern zone, central zone, and western zone have each perennial channels, seasonal
floodplains and occasionally flooded areas and drylands occur. These zones are
differentiated by their responses to local rainfall and upstream inflows. Water levels in the
eastern zone usually increase during the rainy season as a response to local rainfall, and
then decline slightly at the end of the rainy season. This is followed by a subdued increase
as a response to inflows. The central and western zones have weak responses to local
rainfall or minor increases in water levels during the rainy season, but a strong response or
significant increase in water levels due to increase of inflows.
The outflow zone has distributaries draining the Delta, such as the Gomoti, Santantadibe,
Boro, Shashe, Kunyere. The Gomoti, Santantadibe, Boro and Shashe drain into the
Thamalakane which splits to form the Nhabe River flowing into Lake Ngami, and Boteti River
flowing into the Makgadikgadi Pans. The Gomoti, Santantadibe and Shashe have been dry
12
EFA Botswana Wildlife
since the 1990's. The Thamalakane-Boteti and Kunyere rivers are characterised by the
occurrence of high flows during the dry season, July to September. Almost all the flow on
these rivers are derived from outflows from the delta. Another distinctive feature of these
rivers draining the delta is the long-term variation of flows. The Thamalakane-Boteti River
had very little to no flow during the mid-1990's, while high flows occurred during the 1970's
and part of the 1980's.
N
Pa
W
E
nha
S
ndle
Eastern
W
C
e
e
s
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te
tra
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l
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Outflo
Delta rivers
Panhandle
Permanent swamps
0
100
200 Kilometers
Seasonal swamps
Figure 2. 3: Map of the Okavango Delta showing division into zones
2.4 Discipline-specific
description of (Botswana) sites
Site 6: Panhandle at Shakawe
The Okavango River enters Botswana at Mohembo, having travelled some 1000km from its
source, and it is channelled through a 15 km wide corridor between two secondary faults
(Burchart 2000). After entering Botswana at Mohembo, the Okavango River meanders
through papyrus and phragmites swamps (Figure 2.4) before it breaks into three main
channel at Seronga.
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EFA Botswana Wildlife
Figure 2. 4: A photo showing Okavango River meandering through permanent swamps in the
Panhandle
Dominant wildlife in the Panhandle area includes semi aquatic species such as hippo,
crocodile, sitatunga and waterbuck. The permanent swamps flanking the river also provide
suitable habitat for frogs, water snakes, terrapins, otters and water monitors. Terrestrial
grazers such as wildebeest, buffalo, impala, tsessebe and lechwe are not common in the
Panhandle area. High human presence in the Panhandle also contributes to the low numbers
of other species.
Site 7: Eastern Delta around Xakanaxa
The Xakanaxa site on the eastern side of the Delta is typified by a permanent channel known
as the Khwae River flanked by stretches of seasonally and occasionally flooded floodplains.
The floodplains are themselves flanked by stretches of different woodland vegetation. The
eastern side of the Delta supports almost all wildlife found in the whole Delta. Seasonally
flooded floodplains and their associated islands (Figure 2.5) provides suitable habitats for
semi aquatic and aquatic species, at the sometime providing suitable grazing sites for
floodplain grazers when floods recede.
Figure 2. 5: Picture of seasonally flooded floodplains during peak floods
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EFA Botswana Wildlife
Occasionally flooded grasslands (Figure 2.6) of the eastern side of the Delta provides
suitable habitat for terrestrial grazers such as zebra, buffalo, wildebeest and buffalo during
years of high floods reflected in Figure 2.5.
Figure 2. 6: Picture of occasionally flooded areas found in the Xakanaxa area and other parts of
the Delta
Site 8: Chanoga
The Chanoga site lie along the Boteti River which is part of the
15
EFA Botswana Wildlife
3.
IDENTIFICATION OF INDICATORS AND FLOW CATEGORIES
3.1 Indicators
3.1.1 Introduction
Biophysical indicators are discipline-specific attributes of the river system that respond to a
change in river flow by changing in their:
· abundance;
· concentration;
or
· extent
(area).
Social indicators are attributes of the social structures linked to the river that respond to
changes in the availability of riverine resources (as described by the biophysical indicators).
The indicators are used to characterise the current situation and changes that could occur
with development-driven flow changes.
Within any one biophysical discipline, key attributes can be grouped if they are expected to
respond in the same way to the flow regime of the river. By example, fish species that all
move on to floodplains at about the same time and for the same kinds of breeding or feeding
reasons could be grouped as Fish Guild X.
3.2
Indicator list for Wildlife
In order to cover the major characteristics of the river system and its users many indicators
may be deemed necessary. For any one EF site, however, the number of indicators is
limited to ten (or fewer) in order to make the process manageable. The full list of indicators
was developed collaboratively by the country representatives for the discipline Wildlife and
is provided in Table 3.1. Further details of each indicator, including the representative
species of each biological one, are given in Appendix 1and discussed fully in Chapter 4
Sites represented no more than ten
Indicator
indicators per site
Number
Indicator name
1
2
3
4
5
6
7
8
1
Semi Aquatic
X
x
x
2
Frogs, river snakes
x
x
X
3
Middle floodplain grazers (upper
floodplains)
x
x
4
Outer floodplain grazers
x
x
5
Lower floodplain grazers
x
x
Table 3. 1: List of indicators for Wildlife and those chosen to represent each site
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EFA Botswana Wildlife
3.3
Description and location of indicators
Wildlife Indicator 1
Name: Semi Aquatic wildlife
Description:
Main channel and open water (lagoons and pools) dwellers that need sufficient low flow
channel with and depth waters for protection.
Representative species:
Hippopotamus, crocodile
Other characteristic species:
Other aquatic reptiles, otters, terrapins
Flow-related location:
Found through out the Delta where permanent channels, backswamps and extensive
floodplains exist.
Known water needs:
This indicator group require deep permanently flowing water and permanently moist
vegetated channels margins for breeding, protection from high temperatures and predators.
Wildlife Indicator 2
Name: Frogs, river snakes
Description:
Wildlife species found in areas permanently inundated with rooted emergent plants,
submerged plants and floating leafed plants, with margins or tree line dominated by riparian
woodlands. They also require islands / sand bars / rocks for protection, feeding, resting and
breeding sites
Representative species:
Water monitor, snakes, musk shrews and frogs
Other characteristic species:
Other aquatic reptiles and amphibians
Flow-related location:
Found through out the Delta in main channels, permanent swamps formed by backwaters.
Known water needs:
They require shallow to deep permanently to seasonally flowing water and permanently
moist vegetated channel margins for breeding, protection from high temperatures and
predators
Wildlife Indicator 3
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EFA Botswana Wildlife
Name: Middle floodplain (upper floodplain) grazers
Description:
Large mammalian floodplain grazers that utilise higher lying floodplains of grasslands
elevated above the lower/primary floodplains by up to 1m. These floodplains are dominated
by semi-aquatic grasses that become available when floods recede during the otherwise dry
season.
Representative species:
Tsessebe, warthog, wildebeest, zebra, buffalo
Other characteristic species:
elephant, impala
Flow-related location:
Found through out the Delta but dominant in the fan part of the Delta where extensive
floodplains exist.
Known water needs
This key habitat for floodplain grazers requires seasonal flooding for a period of 2-6 months
in years of low flooding intensity and 4 -8 months in years of high rainfall and high flooding
intensity. These floodplains provide water for drinking and high quality forage resources that
become available when floods recede.
Wildlife Indicator 4
Name: Outer floodplain grazers
Description:
Grazers that utilise highest lying islands and grasslands which only flood in years of
extremely high floods, and flood for a very short period of time if they ever flood.
Representative species:
Eland, roan antelope, sable antelope, elephants,
Other characteristic species:
small mammals
Flow-related location:
highest lying islands and grasslands which only flood in years of extremely high floods, and
flood for a very short period of time if they ever flood.
Known water need
This habitat requires periodic short duration flooding.
Wildlife Indicator 5
Name: Lower floodplain areas
Description:
Floodplain grazers that utilise low lying floodplains which are the first to receive flood water
over-spilling from the outlet channels in seasonal swamps, and are the last to recede..
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EFA Botswana Wildlife
Representative species:
reedbuck, lechwe, sitatunga, waterbuck
Other characteristic species:
Aquatic reptiles (crocodiles and water monitor lizards), Aquatic birds (wattle crane, African
and lesser jacana) and painted frogs and other reptiles).
Flow-related location:
Found throughout the Delta where deep permanently flowing water and permanently moist
vegetated channels margins provide breeding sites, protection from high temperatures and
predators. Overspills of the main channels from the main channels create seasonal swamps
dominated by emergent vegetation, floating leaved and submerged plants.
Known water needs
This key wildlife habitat (floodplain grazers in particular) require seasonal flooding for a
period of 4-6 months in years of low flooding intensity and 6 -12 months in years of high
rainfall. These floodplains are key fallback areas for all herbivores when the floods recede
from July to October, providing green and highly nutritious forage during the flooding season
when everything else in the nearby savannas is dry.
3.4
Flow categories river sites
One of the main assumptions underlying the EF process to be used in the TDA is that it is
possible to identify parts of the flow regime that are ecologically relevant in different ways
and to describe their nature using the historical hydrological record. Thus, one of the first
steps in the EFA process, for any river, is to consult with local river ecologists to identify
these ecologically most important flow categories. This process was followed at the
Preparation Workshop in September 2008 and four flow categories were agreed on for the
Okavango Basin river sites:
Dry season
Transitional Season 1
Flood Season
Transitional Season 2.
Tentative seasonal divisions for river Sites 1-5 are shown in Figures 3.1 to 3.5. These
seasonal divisions will be formalised by the project hydrological team in the form of
hydrological rules in the hydrological model. In the interim they provide useful insights into
the flow regime of the river system suggesting, along with the hydrographs, a higher within-
year flow variability of the Cuebe River and a higher year-on-year variability of the Cubango
River.
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EFA Botswana Wildlife
120
Wet
100
Trans
n 1
Trans
n 2
Dry
80
Year
Y
2
ear
60
Year
Y
1
ear
Year
Y
3
ear
40
20
0
O
N
D
J
D
F
M
A
M
J
J
M
J
A
S
Figure 3. 1 Three representative years for Site 1: Cuebe River @ Capico, illustrating the
approximate division of the flow regime into four flow seasons
1200
Wet
1000
Trans 1
Trans 2
n
Dry
800
Year
Y
1
600
Year
Y
2
Year
Y
3
400
200
0
O
N
D
J
D
F
M
A
M
J
J
M
J
A
S
Figure 3. 2 Three representative years for Site 2: Cubango River @ Mucindi, illustrating the
approximate division of the flow regime into four flow seasons
20
EFA Botswana Wildlife
250
1
Wet
2
Dry
200
ans
ans
Tr
Tr
150
Year 1
Year 2
100
Year 3
50
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 3. 3 Three representative years for Site 3: Cuito River@ Cuito Cuanavale, illustrating the
approximate division of the flow regime into four flow seasons
1000
900
Wet
We
800
Dry
Dr
Tra
Tr n
a s
n 1
s
Tra
Tr n
a s
n 2
s
Dry
Dr
700
600
Year 1
500
Year 2
400
Year 3
300
200
100
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 3. 4 Three representative years for Site 4: Okavango River@ Kapoka (hydrological data
from Rundu) illustrating the approximate division of the flow regime into four flow
seasons
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EFA Botswana Wildlife
1800
1600
Wet
1400
Dry
Trans
n 1
Trans 2
Dry
1200
1000
Year 3
00
Year 2
800
Year 1
600
400
200
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 3. 5 Three representative years for Site 5: Okavango river @ Popa (hydrological data
from Mukwe), illustrating the approximate division of the flow regime into four flow
seasons
The literature review (Chapter 4) and data collection and analysis exercises (Chapter
5) are focused on addressing what is initially expected to be nine main questions
related to these flow seasons (Table 3.2).
Question Season
Response of indicator if:
number
1
Onset is earlier or later than natural median/average
2
Dry Season
Water levels are higher or lower than natural median/average
3
Extends longer than natural median/average
Duration is longer or shorter than natural median/average -
4
Transition 1
i.e. hydrograph is steeper or shallower
5
Flows are more or less variable than natural median/average l
Onset is earlier or later than natural median/average
6
Flood
synchronisation with rain may be changed
season
Natural median/average proportion of different types of flood
7
year changed
8
Onset is earlier or later than natural median/average
Transition 2
Duration is longer or shorter than natural median/average
9
i.e. hydrograph is steeper or shallower
Table 3. 2: Questions to be addressed at the Knowledge Capture Workshop, per indicator per
site. In all cases, 'natural' embraces the full range of natural variability
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EFA Botswana Wildlife
3.5
Inundation categories delta sites
The recognised river flow categories are not relevant in the Delta, where inundation is the
major driver of ecosystem form and functioning. The main inundation categories recognised
by the inundation model developed by the Harry Oppenheimer Okavango Research Centre
(HOORC) are used here (Table 3.3).
Inundation
Inundation category name
Description
category
Delta 1
Channel in permanent swamp
Delta 2
Lagoons in permanent swamp
Delta 3
Backswamp in permanent swamp
Delta 4
Seasonal pools in seasonally flooded zones
Delta 5
Seasonal sedgelands in seasonally flooded
zones
Delta 6
Seasonal grasslands in seasonally flooded
zones
Delta 7
Savannah dried floodplain in seasonally
flooded zones
Boteti 1
Wet connected
Boteti 2
Disconnected pools
Boteti 3
Dry
Table 3. 3: Inundation categories for the Okavango as recognised by the HOORC inundation
model
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4. LITERATURE
REVIEW
4.1 Introduction
Literature highlighting the relations between wildlife and flows, and the impact of flow
variation on specific wildlife species of the Okavango Delta is largely scattered, and
unassimilated. However, available literature (e.g. Child 1976; Murray 1997; Rothert 1997;
Bonyongo 1999, 2008; Butchart 2000; Mendelsonhn and Obeid 2004; Ramberg et al. 2006)
has shown that a variety of large browsing and grazing mammals that occur on the open
waters, floodplains and their fringing riparian vegetation, reflect the diversity of habitats and
the high primary productivity facilitated by the pulsing seasonally flooding of the Okavango
Delta. The high habitat diversity and the high primary productivity of are both clearly linked to
seasonal and the long and short term patterns of the flooding of the Okavango Delta (Ellery
and Ellery 1997). Due to the high habitat diversity, the Delta supports, a high diversity of
wildlife ranging from those that are almost totally aquatic or semi-aquatic to animals
completely independent of water except for drinking purposes (Bonyongo 2004).
The most conspicuous populations are found in the Moremi Game Reserve, and a number of
controlled hunting areas adjacent to Moremi Wildlife Game Reserve. More than 400 species
of birds (Kabii 1997, Ramberg 2006), 112 mammal species of 12 orders and 34 families
(Ramberg et al 2006), 33 species of amphibians and 64 species of reptiles (Murray, 1997)
have been recorded in the Okavango Delta. Most mammals of the Delta are small and often
over looked (Ramberg, 2006). In the Delta, 12 reptile species including the Nile Crocodile
and the Nile Monitor, python and five water snakes and four terrapins may be considered
aquatic or near aquatic (Murray, 1997). These reptiles are restricted in their distribution to
areas in or near potential surface water. The abundance and distributions of aquatic reptiles
and amphibians is in the Okavango Delta highly likely to be affected by both natural and
anthropogenic induced changes in water flows.
Large herbivores especially floodplain grazers, are among wildlife species that are wide
spread throughout the Delta which are likely to be affected by anthropogenic changes of
flows. It is highly probable that hydrological modification due to significant water abstraction
upstream of the Okavango River would modify floodplain ecosystems leading to the decline
of some ungulate species, particular the semi aquatic antelopes and other floodplain
grazers. Decline of ungulates populations attributed to human induced changes in
hydrological flows were reported in the Marromeu Delta following construction of three dams
in the Zambezi River catchments (Funston 2006). Funston (2006) also reported that Kariba,
Kafue and Cabora Bassa Dams significantly altered very large floodplains systems leading
to loss of key habitats for both livestock and wildlife. It is therefore imperative to make
reference to what happened to the Zambezi Delta and other systems when considering
large scale developments such as damming and construction pipelines in the Okavango
River basin.
Natural changes in hydrological regimes have been observed to influence populations of
ungulates, especially floodplain grazers and semi aquatic species such as hippo and
crocodile. Bonyongo and Ugutu (2009) hypothesized that in successive years of high floods
and high rainfall which leads to prolonged flooding of floodplains, the population of large
herbivores which use floodplains as fallback areas during the dry season will decline due
loss of floodplain grazing resources. This is because under prolonged high floods,
seasonally floodplains are converted into semi-permanently flooded swamps. Under those
circumstances high quality palatable grasses give way to law quality unpalatable sedges.
On the other hand the population of semi-aquatic and aquatic species will increase because
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EFA Botswana Wildlife
extended flooding enhances the habitat quality for such species. Bonyongo and Ugutu
(2009) showed that on 10 year moving average, the inflow at Mohembo exhibits 60 year
cycle in which 30 years are of averagely high and increasing floods, while the other 30 years
is of averagely low and declining floods (Figure 4.1).
Low populations of floodplain grazers
High populations of floodplain grazers
Figure 4. 1 A 10 year moving average of inflow at Mohembo from 1933 to 2005. Source
(Bonyongo and Ugutu 2009: unpublished manuscript
Natural changes in flooding regime demonstrated in Figure 4.1 serve as a natural regulator
of wildlife population in the Okavango Delta. Bonyongo and Ugutu (2009) modeled the
influence of rainfall on the population trends of the large herbivores in the Okavango Delta,
and found no relationship between trends in rainfall and trends in wildlife populations. Rather,
a density dependent feedback was predicted. This suggests that the shrinking and
expanding of floodplains as result of variation in flooding frequency, intensity and duration
form part of the major drivers of wildlife population in the Okavango Delta.
4.2
Indicator 1: Semi-aquatic
4.2.1 Main characteristics of Indicator 1
The main species that inhabit channels/open water are hippopotamus and crocodile.
Hippopotamus and crocodiles are confined to areas of open waters from where they venture
in short distances to feed on grasses on the higher ground and floodplains at night (Butchart
2000; Mendelsonhn and Obeid 2004). Hippos are an important component of any
wetland/floodplain system. They play a crucial role in the creation and maintenance channels
through out the Okavango Delta. This indicator species is widely distributed throughout the
Okavango Delta with an estimated population of about 3000 (DWNP 2000). They are usually
found in small herds of 10-12 (Burchart 2002). They forage short grasses thus maintaining
grazing lawns for small grazers such as lechwe, reedbuck, impala and warthog.
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EFA Botswana Wildlife
Species Relationship
to
flows
Hippopotamus
Require deep (deep enough to submerge) slow flowing to
stagnant waters of lagoons and main channels for protection and
breeding. Hippo population would immediately decline with drastic
reduction in inflows but would remain stable with increase in flows.
Establishment of new sites of deep water would possible lead to an
increase population.
Crocodile
Require deep water to submerge. Crocodiles spend most of their
time in open waters. They are very sensitive to drop in water
levels. Reduced flows are likely to lead to the disturbance of
crocodile nesting sites.
Okavango Hinged
It occurs in permanent water of rivers, channels, lagoon lagoons
Terrapin,
where it feeds on small fish (Butchart 2000).
Water monitor
Massive aquatic lizard with an elongated snout. Highly depended
in water and would decline in numbers if places of permanent
water would dry up.
Various aquatic
Various snakes and frogs residing in permanent open water would
snakes and frog
decline in numbers if flows decline significantly significant
Table 4. 1: Table showing the semi-aquatic indicator species
Currently the hippo population in the Okavango Delta is believed to be stable although Child
(1976) reported population declines. Child (1976)'s assertion is doubtful because there is not
evidence that shows it was supported by any form of empirical data. In mid 1970s few animal
surveys were conducted in Botswana. Based on data from Department of Wildlife and
National Parks (DWNP) dating from 1989 to 2006, Bonyongo (2004) reported that currently
the population of hippos in Delta are steadily increasing. However, it is important to note that
population of hippos are extremely difficult to ascertain due to their aquatic and nocturnal
behaviour. Although the Okavango Delta still supports a descent population of hippos, their
population is reported to be declining in other similar ecosystems notably the Kafue and the
Zambezi Delta (Builfus and Brown 2006).
Crocodiles are widely spread out through out the Okavango Delta. Their populations are
extremely difficult to ascertain although is widely believed that in the 1970 to late 1980, their
population declined due excessive illegal hunting. Current population dynamics information
on crocodiles including hatching survival rate is lacking (Murray 1997).
Life cycle attributes of Indicator 1: Semi-aquatics
Hippopotamus spends the day resting near water through out the year to keep cool, protect
their skin from sunburn and avoid biting insects (Kingdon 1997; Apps 2000; Butchart 2000).
Hippo leaves water to sunbath on the banks especially during the overcast cool weather in
summer. At dusk, it leaves out of water to feed to feed for 7-8 hours. Because it has a
unique skin which loses water several times the rate of other mammals, a hippo out of water
in hot weather risks rapid dehydration and overheating (Kingdon 1997).
Crocodiles also spend most the time basking near water during the day for protection.
Terrapin also spend time near water during the day basking on logs, and sometimes of the
backs of hippos. Various aquatic reptiles also spend most of their time near water for
protection feeding and nesting.
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Links to flow
All the species of indicator 1 are entirely dependent on water to varying degrees. They
require deep permanently slow flowing water and permanently moist vegetated (emergent,
floating and submerged vegetation) channels and lagoon margins for
breeding/nesting/spawning, resting, feeding, protection from high temperatures and
predators all year round. For example hippos need water up to 1.5m to submerge during the
day and feeds 2-3km from water (Kingdon 1997; Butchart 2000). Development near water
would deprive hippos of feeding sites. Crocodiles also require deep permanent waters to
submerge during the day. These indicator species would decline immediately when flows are
reduced drastically. Rapid increase in water levels is also likely to disturb the ecology of this
indicator group.
4.2.2
Main characteristics of Indicator 2 Frogs and River snakes
This indicator comprises of species which need to spend time near permanent waters of
main channels with small islands of sandbars and vegetated islands. Vegetated islands are
used by this indicator group are also found in backswamps. Members of this indicator group
use these islands for nesting and feeding or resting on exposed sand islands and rock out
crops. Near by water could be swallow or deep but permanent depending on the flooding
season. The islands may be completely covered by water during peak floods and exposed
during low floods. It is during the low floods that crocodiles, otters, water monitors would use
sandbars for resting (Butchart 2000). In the Okavango Delta system, rock outcrops and
extended rock beds are common in the Boteti River.
Life cycle attributes of Indicator 2
The life cycle attributes of indicator are similar to those of indicator 1 because they spend
sometime in water and sometime outside water either to feed, nest or rest.
Links to flows
The links to flows of indicator 2 are similar to those of indicator 1. Therefore the reader is
referred to indicator 1. These species are sensitive to changes in flows. Some of them may
survive the absence of surface water for sometime as long as moist soils exist. This is
particularly so for frogs who may burry themselves in moist soils for protection when there no
water for them to submerge.
4.2.3 Main characteristics of Indicator 3:
Middle floodplain (Upper floodplain grazers) This indicator comprises mainly of terrestrial
grazers which use seasonal floodplains when floods recede. Species in this indicator group
retreat to terrestrial habitats adjacent to floodplains during the rainy season to benefit from
annual grasses that grow in terrestrial habitats when it rains. These species use large home
ranges which enable them to utilise a variety of habitats types given the mosaic and patchy
nature of the Okavango Delta habitats
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EFA Botswana Wildlife
Upper floodplain grazers
Link to flows
buffalo, elephant, impala, zebra
This indicator group require seasonally flooded
waterbuck, tsesebe, wildebeest,
grasslands to provide grazing and resting places.
steenbok, duiker, bushbuck,
Smaller islands surrounded by active floodplains require
waterbuck.
horizontal below ground flows to raise the ground water
table which results improved development of the herb
layer. Larger islands with a higher diversity of grasses
and forbs are grazed by most large grazers of the
Okavango Delta in periods of high floods.
Table 4. 2: Table showing terrestial grazers which utilise seasonal floodplains
Life cycle attributes of Indicator 3
On a large scale, both temporally and spatially, dispersal of wildlife through out the Delta is
influenced by fluctuations in water level and food availability will be reflected by the different
population densities of floodplain grazers over years and seasons (Bonyongo 2004).
Links to flows
When water levels change with the flooding dynamics, species of this indicator group
concentrate on high grounds or disperse on floodplains. When the water level recedes from
August - September, large terrestrial ungulates of this indicator group move in to feed on the
grasses that established or resprouted in upper floodplains. The upper seasonal floodplains
flooding dynamics are to a large extent an influential factor determining the amount of
floodplain grazers found in the Okavango Delta.
In successive years of high floods and high rainfall which leads to prolonged flooding of
upper floodplains, the area floodplain grazers venture to graze can be reduced by as much
as 50%. Ultimately the population of middle/upper floodplain grazers will decline due loss of
floodplain grazing resources. Prolonged high floods convert upper floodplains into semi
permanently flooded lower floodplain type of vegetation at the expense of semi aquatic
grasses which are key to floodplain grazers of this group. Under those circumstances, high
quality palatable grasses give way to low quality unpalatable sedges. This will result in
prolonged nutritional stress which leads to low conception rates, high rates of miscarriage,
stillborns, and ultimately decline populations. This phenomenon is considered natural
population regulation mechanisms (Bonyogo and Ugutu 2009). On the other hand the
population of semi-aquatic and aquatic species increases during high intensity flood
extended flooding enhances the habitat quality for such species.
4.2.4 Main characteristics of Indicator 4 Outer/tertiary floodplain grazers
This indicator comprises of large mammalian herbivores which are not water dependent
except for drinking. They utilise highest lying islands and grasslands which only flood in
years of extremely high floods, and flood for a very short period of time if they ever flooded.
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Outer floodplain grazers
Link to flows
gemsbok, eland, hartebeest,
These are not water dependent except for drinking,
giraffe, kudu, roan antelope,
therefore are not linked to flows.
sable antelope, ostrich,
springbok, rhinoceros
Table 4. 3: Outer floodplain grazers which do not depend on water except for drinking
Life cycle attributes of Indicator 4
Species of this indicator group generally spend most of their time grazing in open woodlands
but my spend time in the ecotones where outer floodplains merge with the woodlands. They
drink in floodplains and floodplain residual pools during the fry season. After drinking, they
may spend time grazing in the upper floodplains.
Links to flows
Species in this indicator group are not directly linked to flows except for drinking water.
These species do not necessarily have to drink regularly though. They are therefore unlikely
to be affected by low to medium decline in flows. Naturally they utilise large home ranges
which enable them to utilise a high diversity of habitats. They also utilise lower and upper
floodplains whenever they are available but are not dependent on floodplains. However, in
years of high floods which lead to flooding of outer or tertiary floodplain, they benefit from
enhanced growth of grasses due to increased soil moisture.
4.2.5
Main characteristics of Indicator 5: Lower floodplain areas
This indicator comprises mainly of semi-aquatic antelopes which need to graze near water
either because they need water to escape from predators or they need to drink regularly.
They include lechwe, reedbuck, sitatunga and water buck (Kingdom 1997). Semi-aquatic and
aquatic antelopes are generally found in lower floodplains bordering semi-permanant and
permanent swamps. The lower floodplains are generally flooded longer but provide very
nutritious forbs, sedges and grasses when the floods recede.
Floodplain grazers
Link to flows
lechwe, reedbuck, sitatunga
Require seasonally flooded floodplains with grasses and
waterbuck
sedges which keep growing in swallow water.
Table 4. 4: Table showing floodplain grazers
Life cycle attributes of Indicator 5
Sitatunga is a swamp dwelling antelope with feet adapted to wet terrain. In the Okavango
Delta, it is found mainly in the Panhandle where stretches of papyrus and phragmites
permanent swamps exist. It is an elusive aquatic antelope confined to the papyrus swamps
and adjacent land (Burchart 2000). Sitatunga feeds on aquatic vegetation as well as on
leaves and grasses of lower and upper floodplains. It is a slow swimmer which uses regular
pathways through the papyrus reeds (Kingdon 1997; Butchart 2000). Sitatunga is active from
daylight to about 11:00am and to about 17:00h when they may emerge to feed on open
grasslands or forests under the cover of darkness (Kingdon 1997). The sitatunga's
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EFA Botswana Wildlife
dependence on swamps for food and cover favours dispersed social organisation and makes
it hard to observe.
Water buck is highly water dependent because it needs to drink regularly. It grazes on open
grasslands within close proximity of water. Lechwe prefer floodplains bordering permanent
swamps. When water level changes with the flooding dynamics, species concentrate on high
grounds or disperse onto the floodplains, the population densities of these species change.
On a large scale, both temporally and spatially, dispersal through out the Delta result of
fluctuations in water level and food availability will be reflected by the different population
densities over the years and seasons (Bonyongo 2004).
Links to flows
Waterbuck is the most water dependent of the aquatic antelopes found in the Okavango
Delta. It is highly susceptible to dehydration during the dry hot days therefore requires to be
near water all the time. Sitatunga is the most aquatic antelope followed by lechwe (Kingdon
1997; Burchart 2000). Most aquatic antelopes use water as an escape route when
threatened by predators. Waterbuck also use water to escape from predators although it
generally prefers dry high ground. Due to the dependence on water as a refuge from
predators, aquatic antelopes cluster together along the shore lines or floodplain edges before
dark descends (Kingdon 1997). Being the most aquatic, sitatunga is so specialised such that
it occurs only in swamps or permanent marshes dominated by sedges (Kingdon 1997).
Most terrestrial predators cannot handle prey efficiently in water; hence floodplains with deep
water and permanent swamps form an important habitat for aquatic antelopes. However,
lions, leopards, spotted hyenas and wild dogs have been observed hunting aquatic antelopes
in water.
Semi-aquatic antelopes depend on the abundant and highly nutritious grasses growing in
inundated floodplains. Such areas are not accessible to most terrestrial grazers which also
utilize floodplains. Therefore high intensity flooding gives competitive advantage to aquatic
antelope over non aquatic floodplain grazers such wildebeest and tsessebe.
Semi-aquatic antelopes are likely to respond to flow variation to a varying degree since their
dependency in water is slightly variable. Lechwe, waterbuck and reedbuck are likely to
respond quickly to a reduction in flow that would lead to a reduction in seasonally flooded
areas. Lose of lower floodplains would immediately led to the decline in lechwe population.
Waterbuck would not respond immediately to lose of floodplains as long as there is sufficient
drinking water from the main channel or residual pools. Permanent swamps are generally
more robust than floodplains which suggest that sitatunga would not be immediately affected
by a reduction in flows.
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EFA Botswana Wildlife
5.
DATA COLLECTION AND ANALYSIS
No new data was collected. However, based on literature, and existing knowledge of the of
Okavango Delta, the distribution of key wildlife indicators was established. Large semi-
aquatic species, frogs and water snakes are common and widespread throughout the Delta.
Hippos and crocodiles are particularly common in all areas where deep flowing and/or
stagnant waters are found. Hippos and crocodiles are among the animals which course
death in many parts of Delta since deep waters they inhabit are also used by human beings
to for various livelihoods activities which include fishing, tourism and transport. Hippos and
crocodiles can be described as abundant in the Panhandle and the Okavango Delta. In the
Boteti River, they can be described as rare to common although the situation is changing due
to the current high floods.
Semi aquatic antelopes are abundant throughout the Okavango Delta but rare to common in
the Panhandle. Their numbers are relatively low in the Panhandle area due to the presence
of human beings who hunted them for bush meet in the past. Sitatunga is common in the
permanent swamps in the Panhandle region. Lechwe is probably the most abundant semi-
aquatic antelopes while waterbuck and reedbuck are the list abundant throughout the Delta
Floodplain grazers are generally wide spread throughout the Delta, particularly in the lower
Delta where seasonal flooded floodplains are abundant. Outer floodplain grazers are
particularly common in the Chiefs Island where they travel short distances from the
woodlands to floodplain especially when floods recede. During the rainy season, most of the
upper and outer floodplain grazers spend most of their time in the woodlands benefit from the
green flush and seasonal ponds for drinking water.
5.1
Methods for data collection and analysis
This study was predominantly desktop based with minimal fieldwork because long-term
observation and sampling were beyond the scope of this study. The analysis of potential
impacts of flow variation on different wildlife, and the potential response of various wild
species benefited from existing literature and the experience accrued by the specialist over
time while working in the Delta. Key literature will include Fleming (1976), Patterson (1976),
Fleming (1976) Robel and Child (1976) Kingdon (1997), Apps (2000), Butchart (2000),
Bonyongo (1999; 2000; 2004) Sites selected during the preparation workshop were visited
mainly to appreciate the similarities and differences in habitats.
5.2 Results
Based on literature and personally knowledge of the Okavango Delta and its wildlife, 5 key
wildlife indicators were identified. They are semi aquatic species, frog and river snakes,
lower floodplain grazers (mainly aquatic antelopes), upper floodplain grazers and the outer
floodplain grazers. A summary of present understanding of the predicted responses of all
wildlife indicators to potential changes in the flow regime is presented in section 5.3.
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EFA Botswana Wildlife
5.3
A summary of present understanding of the predicted
responses of all wildlife indicators to potential changes in the
flow regime
The following tables summarize predicted response of the wildlife indicators to potential flow
dynamics.
32
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5.3.1
Indicator (Semi aquatic)
Table 5. 1 Predicted responce to possible changes in the flow regime of Semi Aguatic species in the Okavango River Ecosystem
Confidence in
Question
prediction (very
Season
Possible flow change
Response of indicator
number
low, low,
medium, high)
Dry season onset would not affect semi aquatic species as long as permanent
Onset is earlier or later than water bodies exist within the system. Whether it comes late or early, it is of no
1
medium
natural
consequence as long as sufficient water needed to facilitate the life cycles of
aquatic species is available.
High water levels would enhance the quality of semi aquatic wildlife habitats which
Dry Season Water levels are higher or
may in turn lead to an increase population. On the other hand, water levels lower
2
High
lower than natural
than natural would lead to the decline in the amount of permanent water bodies
which are key habitats for semi aquatic species.
Long dry season would definitely have a negative impact since will lead to
3
Extends longer than natural reduction in water levels and lose of permanent waters in lagoons and back
High
swamps
Early flood onset might have a slight positive impact especially when it follows
years of low floods. However, if it follows years of high floods, it might not have
Onset is earlier or later than any significant impact. Late floods could have a negative impact because that
4
natural synchronisation
high
could mean an extended dry season especially if it follows years of low floods..
Flood
with rain may be changed
Water levels could drop beyond minimum thresholds for species such as hippo
season
which need to submerge at certain times of the day.
Natural proportion of
Short flood season would result in negative impacts since it could lead to lose of
5
different types of flood year key habitats, while long flooding season would enhance the quality if the habitats
High
changed
which could lead to increase in population of semi aquatic species
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EFA Botswana Wildlife
5.3.2
Indicator 2 (Frogs, River snakes)
Table 5. 2: Predicted responce to possible changes in the flow regime of Frogs, River Snakes in the Okavango River Ecosystem
Confidence in
Question
prediction (very
Season
Possible flow change
Response of indicator
number
low, low,
medium, high)
The onset of the flooding season would not affect the Frogs, Rivers Snakes (as
Onset is earlier or later than
1
well as other small reptiles and amphibians) as long as the river system and its
High
natural
associated floodplains have enough water to meet their minimum requirements
Water levels higher than natural will lead to the establishment of more aquatic
Dry Season Water levels are higher or
environment suitable for species of this indicator group. Water levels lower than
2
High
lower than natural
natural will definitely affect the habitat quality which my in turn lead to the decline
in numbers
Extended dry season will results in loss of aquatic habitats which will lead to the
3
Extends longer than natural
High
decline in population small aquatic amphibians and reptiles.
Early floods would benefit small reptiles and amphibians particularly after a period
Onset is earlier or later than of prolonged droughts because it would immediately make the environment
4
natural synchronisation
conducive for growth and development. However, if the onset is later than usual,
medium
Flood
with rain may be changed
this group would suffer especially if water levels go down to an extent where some
season
water ways dry up.
Natural proportion of
Low floods will definitely affect the quality of the habitat negatively but, contrarily,
5
different types of flood year high floods would enhance the habitat for small reptiles and amphibians leading
changed
prosperity.
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5.3.3
Indicator 3 (Middle Floodplain Grazers)
Table 5. 3: Predicted response to possible changes in the flow regime of Middle Floodplain Grazers in the Okavango River Ecosystem
Confidence in
Question
prediction (very
Season
Possible flow change
Response of indicator
number
low, low,
medium, high)
Onset is earlier or later than Dry season on set would not affect the middle/upper floodplain grazers because
1
medium
natural
these group is not directly water depended.
High dry season volume would also not affect this group except in situation where
Water levels are higher or
it would lead to prolonged flooding of the middle/upper floodplains. Lower dry
2
medium
lower than natural
season volume would not affect middle floodplain grazers for reasons given
Dry Season
above.
As long as is drinking water either in the channel or residual floodplain pools,
longer dry periods would not affect these group of grazers negatively. In fact they
3
Extends longer than natural
medium
may benefit slightly since prolonged dry season results in more unflooded
floodplains to venture on for grazing
Floods that come earlier than natural may negatively affect this group of grazers
Onset is earlier or later than because floodplains might flood at the time when grazers still depend on them. If
4
natural synchronisation
floodplains of the Delta flood during the rainy season, it is highly likely that
high
with rain may be changed
seasonal floodplains will be turned in semi permanent swamps which are not of
any value to floodplain grazers.
Flood
season
Prolonged flooding season will affect the middle floodplain grazers negatively
because that means floods won't recede on time to enable grazers to access the
Natural proportion of
green flush which becomes readily available when floods recede. Under this
5
different types of flood year
high
circumstances, sedges of low quality increase at the expense of high quality
changed
grasses. This group of animals then became nutritionally stressed leading low
conception rate and miscarriages.
35
EFA Botswana Wildlife
5.3.4
Indicator 4 (Outer floodplains)
Table 5. 4: Predicted response to possible changes in the flow regime of Outer floodplain grazers in the Okavango River Ecosystem
Confidence in
Question
prediction (very
Season
Possible flow change
Response of indicator
number
low, low,
medium, high)
Onset is earlier or later than This group of grazers will not be affected by the onset of the dry season since they
1
medium
natural
do not depend on regular flooding.
This group of grazers will benefit from water level higher than natural because
Water levels are higher or
2
Dry Season
that will ensure that the outer elevated floodplains also get flooded leading to
medium
lower than natural
improved forage productivity in those otherwise dry areas.
Extended dry season will not affect this group of grazers since they do not depend
3
Extends longer than natural
medium
directly on flooding.
Onset is earlier or later than This group of grazers will not be affected by the onset of the flooding season since
6
natural synchronisation
they do not depend on regular flooding. As long as there is drinking water either in
medium
with rain may be changed
the floodplain residual pools or in the channel, they will be fine
Flood
season
If the flooding season is longer than natural, this is likely to benefit this group of
Natural proportion of
grazers because such can only happen in years of very high floods. Under such
7
different types of flood year
medium
circumstances the outer floodplains will afford to get flooded leading to better
changed
quality of forage.
36
EFA Botswana Wildlife
5.3.4
Indicator 5 (Lower floodplain grazers)
Table 5. 5: Predicted response to possible in the flow regime of Lower floodplain grazers in the Okavango River Ecosystem
Confidence in
Question
prediction (very
Season
Possible flow change
Response of indicator
number
low, low,
medium, high)
This group of floodplain grazers will not be affected in any way by early floods, but
Onset is earlier or later than are likely to be affected by late floods. Late floods would deprive species such as
1
medium
natural
lechwe of the much needed flooded lower floodplains which they use as escape
routes when predators charge.
Water level which are higher than natural are unlikely to affect this group of
Dry Season Water levels are higher or
grazers negatively but water levels which are lower than natural will lead to loss of
2
medium
lower than natural
floodplain ecosystems., much to the detriment of lower floodplain grazers/ Their
population will decline under such circumstances.
An extended dry season would mean floodplains remain unflooded for a long
3
Extends longer than natural period of time meaning that semi aquatic antelopes which use lower floodplains
medium
will lose their preferred habitat, thus exposing them to predators.
Onset is earlier or later than An early onset will be of benefit to lower floodplain grazers especially if that follows
6
natural synchronisation
a year of lower floods. Late floods would negatively affect the habitats of the semi
medium
Flood
with rain may be changed
aquatic antelopes
season
Natural proportion of
If the flood season is longer than normal, semi aquatic antelopes will benefit since
7
different types of flood year such circumstances will lead to improved habitats..
medium
changed
37
EFA Botswana Wildlife
5.4 Conclusion
38
EFA Botswana Wildlife
6. REFERENCES
Apps, P. (2000). Smothers' Mammals of Southern Africa, A field guide.Strul
Publishers.
Biggs, R. C. (1979) The ecology of Chief's Island and that adjacent floodplains of the
Okavango Delta, Botswana. MSc thesis, University of Pretoria, Pretoria.
Bonyongo, M. C. (1999) Vegetation ecology of the seasonal floodplains in the
Okavango Delt, Botswana. MSc. thesis, University of Pretoria, Pretoria.
Bonyongo, M. C., Bredenkamp, G. J. & Veenendaal, E. (2000). Floodplain vegetation
in the Nxaraga Lagoon area, Okavango Delta, Botswana. South African
Journal Botany, 66, 15-21.
Bonyongo, M.C., 2004. The ecology of large herbivores in the Okavango Delta,
Botswana. University of Bristol. Bristol. UK.
Butchart, D., (2000). Wildlife of the Okavango Delta: Common animals and plants.
Struik.
DWNP (2000). Aerial Surveys report. DWNP, Gaborone
Ellery, K. & Ellery, W. (1997) Plants of the Okavango Delta: A Field Guide. Tsaro
Publishers, Durban.
Ellery, K. (1987) Wetlands plant community composition and successional process in
the Maunachira River system of the Okavango Delta. M. Sc. thesis, The
University of Witwatersrand.
Ellery, K., Ellery, W. N., Rogers, K. H., & Walker, B. H. (1991) Water depth and biotic
insulation: Major determinants of back-swamp plant community composition.
Wetland Ecology and Management, 1, 149 - 162.
Ellery, W. N., Ellery, K., Rogers K. H., McCarthy, T. S & Walker, B. H. (1990)
Vegetation of the channels of the north-eastern Okavango Delta, Botswana.
African Journal of Ecology, 28, 276-290.
Kabii, T. (1997) Ramsar archives: Okavango - the world's largest Ramsar site.
http://www.ramsar.org/sitelist
Kingdon, J. (1997) The Kingdon Field Guide to African Mammals. Academic Press,
San Diego.
Mendelsohn, J. and S el Obied.( 2004). Okavango River: the flow of a lifeline. Struik,
Cape Town
Merron, G. S. (1991) The ecological management of fishes in the Okavango Delta,
Botswana, with particular reference to role of seasonal floodplains. PhD
thesis, Rhodes University.
39
EFA Botswana Wildlife
Murray, M. (1997) Fauna of the Okavango River basin (Botswana sector). Permanent
Okavango Commission, Preparatory Assessment study.
Patterson, L. (1976). An introduction to the ecology and zoogeography of the
Okavango Delta. In: The Proceedings of the symposium on the Okavango
Delta and its future utilisation. Botswana Society. Gaborone.
Ramberg, L., Hancock, P., Lindholm, M., Meyer, T., Ringrose, S., Sliva, J., Van As,
J., & Vanderpost C. (2006). Species Diversity of the Okavango Delta. Aquatic
Sciences, 68: 310 337
Rothert, S. (1997) Which way Okavango? Conservation and Management of Wildlife
in Botswana. DWNP.
40
APPENDIX A: FULL DESCRIPTIONS OF INDICATORS
Habitat
Indicator/ habitat type
Major wildlife
Flow requirement and
major ecological role
Open water flowing deep and
Hippopotamus,
Requires deep
permanent channel flanked
crocodile and other
permanently flowing
predominantly by papyrus and
aquatic reptiles,
water and
phragmites reeds
cape clawless otter, permanently moist
Semi
aquatic birds.
vegetated channels
Aquatic
margins for breeding,
Wildlife
protection from high
temperatures and
Frogs, river
predators, and
snakes
foraging
Permanent swamps - areas
Hippopotamus,
Requires
permanently inundated with
crocodile, water
permanently slow
rooted emergent plants,
monitor lizard,
flowing water with
submerged plants and floating
otters, terrapins,
depth varying
leafed plants, with margins or
aquatic birds (wattle seasonally.
tree line dominated by riparian
crane) and aquatic
Vegetation provides
woodlands.
antelopes
protection and
(reedbuck, lechwe,
breeding sites.
sitatunga,
Emergent, floating
waterbuck)
and submerged
vegetation also
provides food to
various forms of
wildlife.
i). Primary floodplains / Lower
Aquatic reptiles
Requires seasonal
floodplains low lying
(crocodiles and
flooding for a period
Lower
floodplains which are the first to
water monitor
of 4-6 months in
floodplain
receive flood water from the
lizards), Floodplain
years of low flooding
grazers
outlet channels in seasonal
grazers which
intensity and 6 -12
swamps, and are the last to
include
months in years of
recede. Domintated by sedges,
hippopotamus,
high rainfall and high
aquatic grasses and aquatic
lechwe, reedbuck,
flooding intensity.
forbs. Depth and duration of
elephants, and in
Key fall back area for
flooding to vary depending on the some cases buffalo
all herbivores when
annual rainfall intensity and the
and zebras have
the floods recede
annual inflow at Mohembo.
been observed
from July to October.
grazing in water
Provides green and
highly nutritious
forage during the dry
season when
everything else in the
nearby savannas is
dry and of low quality.
41
EFA Botswana Wildlife
Middle/Uppe
ii). Secondary
Large mammalian
Requires seasonal
r floodplain
floodplains/Upper floodplains
floodplain grazers
flooding for a period
grazers
higher lying floodplains of
mainly impala,
of 2-6 months in
grasslands elevated above the
lechwe, wildebeest,
years of low flooding
primary floodplains by up to 1m.
zebra, tsessebe,
intensity and 4 -8
Dominated by semi-aquatic
buffalo, warthog,
months in years of
grasses. Composition varies in
elephants, small
high rainfall and high
accordance with accordance with
mammals, and
flooding intensity.
flooding frequency, duration and
amphibians
Provide forage for all
grazing intensity.
grazers of the
Okavango Delta
during the dry
season, after the
floods recede.
Availability and
accessibility of
secondary floodplain
grasslands determine
the amount of wildlife
found in the adjacent
woodlands.
Outer
iii). Tertiary floodplains and
The smaller islands
Provide grazing and
floodplain
Island grasslands highest
grasslands
resting places for
grazers
lying islands and grasslands
dominated by
floodplain grazers.
which only flood in years of
Sporobolus sp. are
Smaller islands
extremely high floods, and flood
predominantly
surrounded by active
for a very short period of time if
grazed by
floodplains require
they ever flooded.
hippopotamus,
horizontal below
lechwe, impala and
ground flows to raise
warthog.
the ground water
table. Larger islands
with a higher diversity
of grasses and forbs
are grazed by most
large grazers of the
Okavango Delta in
periods of high
floods.
42
EFA Botswana Wildlife
The Okavango River Basin Transboundary Diagnostic Analysis Technical Reports
I
Diagnostic Analysis to establish a base of available
n 1994, the three riparian countries of the Okavango
scientific evidence to guide future decision making.
River Basin Angola, Botswana and Namibia agreed
The study, created from inputs from multi-disciplinary
to plan for collaborative management of the natural
teams in each country, with specialists in hydrology,
resources of the Okavango, forming the Permanent
hydraulics, channel form, water quality, vegetation,
Okavango River Basin Water Commission (OKACOM).
aquatic invertebrates, fish, birds, river-dependent
In 2003, with funding from the Global Environment
terrestrial wildlife, resource economics and socio-
Facility, OKACOM launched the Environmental
cultural issues, was coordinated and managed by a
Protection and Sustainable Management of the
group of specialists from the southern African region
Okavango 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 project
River Basin Trans-boundary Diagnostic Analysis
produced the Transboundary.
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
Especialista: País: Angola: Disciplina: Sedimentologia &
43
EFA Botswana Wildlife
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
44
EFA Botswana Wildlife
Botswana Chimbari, M. and
Okavango River Basin Trans-Boundary Diagnostic Assessment
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
45
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