Bokaa Dam (6053)
Botswana, Africa
Site overview
KBA status: confirmed
Global KBA criteria: A1b, D1a
Year of last assessment: 2001
National site name: Bokaa Dam
Central coordinates: Latitude: -24.4500, Longitude: 26.0000
System: freshwater, terrestrial
Elevation (m): 1000 to 1000
Area of KBA (km2): 5.669654
KBA classification: Global
Legacy site: Yes
Site details
Site description: A reservoir constructed during 1990 and 1991 by damming a tributary of the Ngotwane river just south of the village of Bokaa, less than 20 km north of Gaborone. The body of open water stretches for some 6 km or more and is over 500 m wide at its maximum; it has a north-west side-arm where the Kopong tributary joins the watercourse formed by the Metsemotinaba, Gakgatia and Gamoleele and other tributaries. The dam is surrounded by Acacia savanna, which is used for grazing by many sheep, goats, donkeys and cattle, and away from the reservoir there are some cultivated areas. Some sections of the shore are open bare mud but there are patches of Cyperus, Phragmites and other emergent aquatic vegetation although this is rather sparse and degraded because of pressure from domestic stock. Although the reservoir has a perimeter fence this is broken in several places so stock have access to much of the reservoir edge. One point on the southern shore is used as a picnic site by weekend visitors. The west side of the north-west arm of the reservoir is fringed by taller trees which support a large mixed heronry.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.
Additional biodiversity: See Box for key species. Bokaa Dam occasionally supports small numbers of Pelecanus rufescens. Waterfowl counts between 1991 and 1995 reached a maximum of c.4,000 birds. The only species present in numbers exceeding the 0.5% threshold are Podiceps cristatus (max. 46) and Netta erythrophthalma, numbers of the latter having built up since 1994, usually peaking during the August–October period. Non-bird biodiversity: None known to BirdLife International.
Habitats
Land use: agriculture | forestry | tourism/recreation | water management
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Artificial - Aquatic | 100 |
Threats
Summary of threats to biodiversity at KBA: Problems include damage to emergent vegetation from grazing by domestic stock, disturbance to waterfowl by hunting and by picnickers with dogs and by car-washers, and degradation of surrounding savanna by tree-cutting and clearance for cultivation.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Climate change & severe weather | Storms & flooding | Ongoing |
Additional information
References: Bishop (1991–1996), Tyler (2001).