Abstract
Sustainable groundwater exploration for productive and safe water in semi-arid basement aquifers remains crucial to addressing water security issues. In Sub-Saharan Africa, such aquifers are the primary source of groundwater during climatic shocks, such as droughts, particularly in rural areas where most people live. However, groundwater exploration in semi-arid basement aquifers remains challenging, with a substantial number of boreholes reported as dry before final successful drilling. The study assessed current groundwater exploration methods for siting productive boreholes in semi-arid basement aquifers in Zimbabwe. Data were gathered from 15 Focus Group Discussions (FGDs), 10 Key informants, and 250 groundwater exploration reports purposively sampled from a sample frame of 522 boreholes drilled across five semi-arid basement districts: Rushinga, Mudzi, Nyanga, Buhera, and Gwanda, from 2019 to 2024. The data were triangulated with field observations and measurements prior to thematic content and statistical analyses. Conventional hydrogeophysical methods (58.8%) were the most commonly used groundwater exploration approaches across the study districts. Using indigenous knowledge (IK) alone was relatively ineffective (Odds ratio ≈ 0.38; p = 0.02) compared with the hydrogeophysical approach. However, the odds of siting a productive borehole significantly improved (Odds ratio ≈ 4.92; p < 0.001) when IK and hydrogeophysical methods were combined, compared with the hydrogeophysical method applied independently. From FGDs, the main indigenous knowledge indicators of groundwater, as reported by local people, include termite mounds, vegetation type and health, especially during the dry season, and geomorphological features such as streams and valleys. It can be concluded that the high frequency of low or dry borehole occurrences is due to a lack of systematic groundwater exploration approaches that leverage indigenous knowledge, Geographical Information Systems, Remote Sensing, and hydrogeophysical insights. The study recommends the development of explicit, integrated, and systematic multi-tier groundwater exploration approaches to enhance the groundwater exploration process in semi-arid basement aquifers.
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