Abstract

Introduction

In many hydrogeological investigations, particularly those involving crystalline basement aquifers in Third World countries, it has not been possible to obtain good data on the aquifer characteristics. This shortcoming arises from a variety of reasons, including the lack of funds to carry out large-scale pumping tests, the lack of suitable boreholes for test pumping and the local lack of availability of appropriate testing equipment.

In a recent study carried out in southwestern Uganda, the Waterra inertial pump, originally designed as a low-cost dedicated sampling device for ground-water monitoring holes, was effectively used in conjunction with pneumatic packers to obtain hydraulic conductivity profiles in both new and existing boreholes.

The work was carried out as part of a research project funded by the International Development Research Centre (IDRC) of Canada and primarily utilized boreholes being drilled as part of a UNICEF/ Government of Uganda rural water supply project.

Background

In 1980, UNICEF and the Government of Uganda undertook an ambitious programme of borehole drilling in rural areas of the country. Using downhole hammer rigs, 115 mm diameter boreholes were drilled through the regolith and into the unweathered Precambrian basement rocks. The regolith was then cased off and the borehole continued to a depth, sometimes in excess of 100 metres, where the drillers thought that a yield of at least 5 l/min would be obtained. Once the drilling was completed the yield was estimated by airlifting and, if adequate, a locally manufactured version of the India Mk II handpump was installed in

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