The role of superficial geology in controlling groundwater recharge in the weathered crystalline basement of semi-arid Tanzania

•Conceptual hydrogeological models of groundwater recharge in semi-arid Tanzania.•Electrical Resistivity Tomography (ERT) defines geometry of superficial geology.•Superficial deposits redistribute surface water to bedrock aquifer via permeable pathways.•Overbank streamflow increases the probability of activating these pathways.•First step in modelling groundwater recharge in drylands with variable geology.