Lithological Controls on Groundwater Recharge, Storage and Catchment Hydrology in East Africa: A Scoping Review

Rock type, weathering and structure determine where water is stored and how quickly it moves through a catchment, yet the evidence linking lithology to hydrological behaviour in East Africa has not been mapped. This article reports a scoping review, structured by PRISMA-ScR and the Joanna Briggs Institute framework, of sources that relate lithological or structural properties to groundwater recharge, aquifer storage, borehole yield or streamflow, with emphasis on East Africa. Nineteen sources published between 1992 and 2022 were charted: fifteen from Africa and four comparators from outside the continent. Nine African sources concern crystalline and metasedimentary basement, two concern volcanic terrain in Ethiopia and four are pan-African syntheses. The charted evidence indicates that the weathering profile, rather than parent rock alone, controls storage and transmissivity in basement aquifers; that recharge in tropical Africa is episodic and tied to rainfall intensity; that high-yielding abstraction depends on thick regolith or superficial sediments; and that faults and lithological contrasts organise flow in volcanic rift terrain. Direct tests of lithological control on streamflow come almost entirely from temperate and montane catchments. No charted African source compares streamflow generation across contrasting lithologies within one catchment, and none measures rock moisture in tropical regolith. The article proposes a research agenda based on regolith characterisation, paired hydrometric monitoring, lithology-aware catchment models and long-term piezometry, and considers its relevance for south-western Uganda. Because the search was not run in subscription bibliographic databases, the charted set should be read as a core rather than exhaustive body of evidence.