Basement Aquifer Project : Progress Report for 1987-1988

Crystalline rocks have a widespread extent, approximately 30% in global cover, and are of particular importance in the tropical and subtropical regions of Africa, South America and South Asia (Figure 1.1). They occur in a wide variety of physiographic and climatic regions. Current and planned developments of crystalline rock aquifers are on a large scale and overall very costly. Because of the generally low productivity of boreholes and wells in these aquifers, development is mainly for rural water supply using a point source distribution. Basic service cover (25 lcpd) for Africa's 360 million people averages 38% and includes only 26%* of the rural population. Up to a million water points may be needed to simply meet Decade basic requirements with costs in the range 10-20 thousand million dollars. It is estimated that the majority of the rural population of Sub-Saharan Africa will have to rely on groundwater from basement aquifers for basic domestic supply. To summarise the reasons for the importance of the basement aquifers: widespread extent, relatively low cost of exploitation because of shallow depth to groundwater; in many areas no alternative sources of supply.