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Water Management Consultants, 2/3 Wyle Cop, Shrewsbury, Shropshire SY1 1UT, UK
Two rural water supply projects based on groundwater sources are described and compared. One in Nigeria aimed to provide yields of greater than 1 l/s using electric submersible pumps to villages and towns with populations from 2000 to 30 000; the other in Zimbabwe aimed to supply yields greater than 0.2 l/s using hand pumps to small communities and villages from 100 to 2200 people. The higher yields in Nigeria are examined in relation to geology and aquifer characteristics, aquifer recharge, siting methods and borehole design. It is found that the higher yields are partly due to the criterion used to define a ‘successful’ borehole and partly due to other factors. Geology and aquifer characteristics appear to be similar in both places but recharge is much higher in Kwara State, leading to higher water levels and higher potential yields. A greater use of geophysics in Kwara State leads to a higher success rate and greater drilled depths into the bedrock in Kwara State also contribute to higher yields.
