ABSTRACT
In semi-arid countries groundwater resources form an important component for the drinking water supply since surface water is usually scarce. In order to evaluate the long-term availability of groundwater it is essential to assess the recharge of the most important aquifers. Botswana is such a country, largely near-desert, with a rainfall pattern characterized by short, intense rainfall events separated by relatively long dry periods and a very high potential evaporation; up to 2000 mm/year. Annual rainfall averages about 460 mm, though this figure is highly variable in time (Botswana is periodically subject to droughts) and in space; e.g. varying from 635 mm in the North near the Okavango Delta to 230 mm or less in the Western Kalahari desert near Namibia.
