In Botswana, the only surface water resources are found in the Okavango Delta and the Chobe District to the North and the East of the country respectably. Throughout the rest of the country, the population relies entirely on groundwater. At the present rate of use and low levels of recharge, future demand may not be met without innovative wastewater re-use programs (Government of Botswana 2001). About two-thirds of Botswana is found in the Kgalagadi (Kalahari) or Sandveld, including the portion of the country in the Orange-Senqu River basin. This area is largely dependent on groundwater located under the pans of the area. There are several endorheic or mekgacha river systems in the Kgalagadi that used to support large surface water river systems. These systems can be seasonally flooded in some areas and support the recharge of remaining high-yielding aquifers.
In the 1950s Botswana accessed water in the Hardveld and Sandveld areas through boreholes. There are now an estimated 21 000 boreholes in the country, of which half are no longer in use and half are owned by the government. Groundwater supplies approximately two-thirds of Botswana’s water and most of the sources are geologically old, meaning that the water quality could be affected by salinity, fluoride and faecal contamination (Aquastat Botswana 2009). Unfortunately, maintaining groundwater access can be costly (HDR 2005).
The majority of small-scale dams on the smaller rivers found in the country are affected by sedimentation. 240 earth dams have been constructed since the 1970s but again these suffer from sedimentation and lack of maintenance. Most of these rivers and dams are not in the portion of Botswana lying in the Orange-Senqu River basin.
Groundwater is the primary source of water in Botswana in the Orange-Senqu River basin.
Source:DWA Botswana 2001
( click to enlarge )