Delineating groundwater potential zones with GIS and analytic hierarchy process techniques: the case of Great Ruaha River catchment, Tanzania

Abstract

The Great Ruaha River Catchment (GRC) in Tanzania is facing severe water scarcity due to the growing number of water users in the catchment. The surface-water resources are under stress, leading to increasing dependence on groundwater for water supply. This study aimed to identify and map groundwater potential areas in the GRC using a geographic information system (GIS), remote sensing techniques, and analytic hierarchy process multi-criteria decision analysis (AHP MCDA) tools. The thematic maps representing lithology, lineaments density, precipitation, soil, slope, drainage density, geomorphology, and land use were used to create a groundwater potential zones (GWPZ) map by weighted linear combination (WCL). The results showed that 70% (~60,044 km²) of the catchment area is in zones with moderate groundwater potential, 21.9% (~18,720 km²) in high groundwater potential zones, and 7.87% (~6,726 km²) in low groundwater potential zones. These results highlight the catchment’s overall groundwater potential and identify areas with scarce resources that should be prioritized for protective measures. Watershed managers and policymakers can use this information to make informed decisions on groundwater use and protection, and determine suitable areas for new wells that may have greater yield.