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.