Okavango Delta, Botswana

Site Details
Assessment Details

Site Overview


KBA status: Global

Rationale for qualifying as KBA: Global: a KBA of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.

Priority for re-assessment against the Global KBA Standard.

For further details on this site and its significance as an Important Bird and Biodiversity Area, see here.

Global KBA criteria: A1b, B1, D1a
Year of assessment: 2001
National site name: Okavango Delta
Central coordinates: Lat: -19.42 Long: 22.75
System: Terrestrial, Freshwater
Altitude (m): 900 to 1,000
Area of KBA (ha): 1,404,872
Protected area coverage (%): 100

Text account


Year of compilation: 2001
Site description:

The Okavango Delta, lying between 18°20’S and 20°00’S, and 21°50’E and 23°55’E, is undoubtedly the most important wetland in southern Africa. An extensive wetland system in northern Botswana, in the semi-arid Kalahari sandveld region, it is the largest wetland (and largest Ramsar Site) in southern Africa and has a greater range of habitats than any other wetland in the region. The Okavango river enters Botswana from Namibia as a single meandering channel, following a minor north-west to south-east rift that forms the ‘Panhandle’ of the delta. The delta is formed where a low gradient (1:3,500) and dense vegetation cause the water in the river to fan out, filling an extensive flood-plain and saturating the sandy soils. One fault (Gumare), running north-east to south-west, limits the northern end of the wetland, and two parallel faults (Kunyere and Thamalakane) the southern end. Where the river crosses the Gumare fault, it splits into four channels: the Selinda or Mogwegana, flowing north-east into the Linyanti river, the Ngoqa/Mwanachira (east), the Jao/Boro (south-east) and, in the west, the Thaoge (south). At the northern tip of Chief’s Island, in Moremi Game Reserve, the Ngoqa–Mwanachira splits again into the Kwai system (east) and the Mboroga–Gomoti–Santantadibe system (south-east).The flow patterns of the delta are highly dynamic, due to the build-up of silt in river channels. Currently, due to a series of years with lower-than-average rainfall, flow levels in the delta are very low, but the main flow is in the Ngoqa–Mwanachira–Mogogelo system. When flows are high, water from the delta reaches the Thamalakane river, which flows through Maun and then into the Boteti river, and the Nhabe and Kunyere rivers, which flow south-west into Lake Ngami. (Lake Ngami, whilst an integral part of the Okavango Delta, is treated as a separate IBA, BW004.)The main habitats in the delta are open clear water (rich in aquatic plants), permanent swamp dominated by papyrus Cyperus and Miscanthus, seasonal swamps dominated by reed Phragmites, and river flood-plain dominated by grasses, which grades into areas of dry land with trees, including higher sandveld areas such as the sandveld tongue of Moremi Game Reserve which is dominated by mopane woodland. There is a complex mosaic, within these main habitats, of lagoons, swamp vegetation, channels, islands, seasonally flooded depressions or pans, riparian woodland and drier woodland and grasslands. The delta has a diversity of trees, from semi-aquatic figs Ficus and wild date palms Phoenix, to knobthorn Acacia and fan palms Hyphaene on the marginal flood-plains, to the drier mopane and mixed Acacia woodlands.The main land-uses are tourism, sport- and subsistence hunting, recreational and artisanal fishing, cutting of grass, sedges and reeds and gathering of veld products (plants and insects) for food, arrow poison and basketry; human settlements (some inside the buffalo fence), cattle-grazing outside the buffalo fence and some arable production occur in the north-west and south-west. Under a newly introduced land-use plan, the majority of revenues generated from tourism and hunting are channelled to local authorities and communities.

Summary of threats to biodiversity at KBA:

The site is partly protected by Moremi Game Reserve, which covers 4,871 km² in the east, and by Wildlife Management Areas. About 75% of the area outside Moremi Game Reserve is designated as multiple-use Controlled Hunting Areas, where traditional rights to hunt, fish and collect veld products exist alongside commercial safari/tourism use. The delta was designated a Ramsar Site in 1996.A buffalo fence restricts movement of game to the north, west and south, but also keeps cattle out of much of the delta to prevent their coming into contact with Syncerus caffer under the Diseases of Animals Act. Cattle occur to the north-west of the delta in the ‘Panhandle’. An extension in 1997 of the northern buffalo fence to the Namibian border severely restricts migratory game, as too does a new double fence constructed in 1997 along the Namibian border to stop cattle movements to or from Namibia. Serious local overgrazing by cattle and goats occurs in some of the communal planning areas with wind erosion recorded in the west. Overgrazing by cattle and donkeys along the Thamalakane and Boro rivers has caused deterioration in riverine and flood-plain plant communities. Tsetse-fly control measures (destruction of wildlife, bush-clearing, ground-spraying with dieldrin and DDT in the early years, aerial spraying with endosulphan and other chemicals between the 1960s and 1980s and, more recently, the use of insecticide-treated, odour-baited targets to which the flies are attracted) have been operational in parts of the delta since the 1920s. Aerial spraying with Deltamethrin, a pyrethroid insecticide, is due to take place over extensive areas of the delta in May 2001.The two main issues in the Okavango Delta, other than veterinary fences, are future land-use and water needs.Whether the delta continues to be used primarily for wildlife-based industries or for agriculture and livestock is the crucial question. Expansion of the agriculture and livestock industry into the delta would cause ecological degradation. The livestock industry outside the main delta is ecologically non-sustainable and is generating pressure on the delta. Immediate issues include an increasing human population and settlements within and on the periphery of the delta; burning and cultivating of areas formerly dominated by papyrus Cyperus in the west of the delta; burning and cutting of mature reedbeds, which deplete nesting habitat for the near-endemic Egretta vinaceigula, and roost- and nest-sites for other species; overgrazing by cattle; veterinary cordon fences which prevent movements of game and thereby affect the vegetation; the increase in elephants which may be adversely affecting vegetation and other species of game; disturbance to vulnerable species such as Rynchops flavirostris and to heronries from motorized tourist craft and planes, as well as from humans, cattle and mokoro (canoes); wash from boats destroying nests; conflicts between traditional use of natural resources and commercial use for tourism and related activities; and over-hunting and over-use of natural resources (for example, the high bag-limits and lack of close season during the breeding period may have caused a large decline in sandgrouse Pterocles numbers; large-scale fishing with monofilament gill-nets may be reducing fish populations). The blockage of channels, following the over-hunting of Hippopotamus amphibius which formerly kept areas of water clear of vegetation, is sometimes perceived as an issue. Whilst there is little evidence for this, Hippopotamus has been severely reduced in the western delta.The need for more water in Botswana led to a proposal in the late 1980s for the Boro river to be dredged and canalized and water transferred to a reservoir near Maun. This Southern Okavango Integrated Water Development Project was at an advanced stage, contracts already having been awarded, before it was dropped by the government following strong local opposition and at the recommendation of the IUCN in 1992. Botswana has continually increasing water requirements, which will create increasing demands on the Okavango’s waters. The same is true for Namibia and Angola, whose governments have current schemes to take water from the Okavango river before it reaches Botswana. During a drought, the problem is exacerbated both by increased demands and reduced flows. Water extraction must be kept below levels that will cause irreversible changes to the ecology of the delta and physical interventions such as dredging of channels should be avoided so that the delta flow system remains dynamic and flexible. A tripartite water commission, OKACOM, exists between Botswana, Namibia and Angola. OKACOM, in 1997, began a broad environmental assessment of the river and delta as a basis for water abstraction. Drought in Namibia prior to 1996/97 led the Namibian government to put forward an emergency pipeline scheme to transfer water from the Okavango river to Windhoek, in advance of the findings by OKACOM. Good rains in the 1996/97 summer caused a deferment of the scheme. An environmental assessment of that scheme has been produced, but will be incorporated into the OKACOM study.

Habitats


IUCN Habitat Coverage level Coverage % Habitat detail
Shrubland - 55
Grassland - 44

Threats


Threat level 1 Threat level 2 Threat level 3 Timing Scope Severity Impact
Agriculture & aquaculture Annual & perennial non-timber crops Shifting agriculture happening now some of area/population (10-49%) moderate to rapid deterioration high
Agriculture & aquaculture Livestock farming & ranching Agro-industry grazing, ranching or farming happening now majority/most of area/population (50-90%) moderate to rapid deterioration high
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases Named species happening now majority/most of area/population (50-90%) slow but significant deterioration high
Climate change & severe weather Storms & flooding happening now majority/most of area/population (50-90%) moderate to rapid deterioration high
Energy production & mining Mining & quarrying likely in long term (beyond 4 years) small area/few individuals (<10%) very rapid to severe deterioration low
Biological resource use Hunting & trapping terrestrial animals Persecution/control happening now small area/few individuals (<10%) slow but significant deterioration low
Biological resource use Hunting & trapping terrestrial animals Intentional use (species is the target) happening now small area/few individuals (<10%) slow but significant deterioration low
Residential & commercial development Tourism & recreation areas happening now some of area/population (10-49%) slow but significant deterioration medium
Human intrusions & disturbance Work & other activities happening now some of area/population (10-49%) slow but significant deterioration medium
Human intrusions & disturbance Recreational activities happening now some of area/population (10-49%) slow but significant deterioration medium
Agriculture & aquaculture Annual & perennial non-timber crops Small-holder farming likely in short term (within 4 years) some of area/population (10-49%) slow but significant deterioration medium

Recommended citation


Key Biodiversity Areas Partnership (2020) Key Biodiversity Areas factsheet: Okavango Delta. Extracted from the World Database of Key Biodiversity Areas. Developed by the Key Biodiversity Areas Partnership: BirdLife International, IUCN, American Bird Conservancy, Amphibian Survival Alliance, Conservation International, Critical Ecosystem Partnership Fund, Global Environment Facility, Global Wildlife Conservation, NatureServe, Rainforest Trust, Royal Society for the Protection of Birds, World Wildlife Fund and Wildlife Conservation Society. Downloaded from http://www.keybiodiversityareas.org/ on 27/11/2021.