Analyzing the determinant factors of spatial groundwater availability in the Akaki catchment, Central Ethiopia

Human activities and climate change are hindering water supply in the Akaki catchment. This issue is aggravated due to excessive groundwater withdrawal. Hence, this study investigated the spatial availability of groundwater within the catchment by considering eight different factors. The analytical hierarchy process (AHP) was conducted using geospatial modeling system software (TerrSet- v.19.0.6). Through the analysis, it was assigned that lithology (31%), rainfall (23%), lineament density (18%), drainage density (11%), slope (6%), land use (4%), soil (4%), and elevation (3%) influence groundwater availability in the catchment. Pair-wise computations showed an acceptable range, displaying a consistency ratio below 0.1. Subsequently, a weighted overlay revealed that approximately 41% of the catchment area situated in the Northeast, Central, and Northwest regions is characterized by moderate groundwater available zone. About 43% of the catchment, located in the Northwest, Central, and Southeast regions, is mapped as a high groundwater available zone. In the southern part, an area covering approximately 15% of the catchment, has been identified as a very high groundwater available zone. Furthermore, single-parameter sensitivity analysis indicated that lithology, rainfall, and lineament density were the parameters most sensitive to identifying groundwater available zones. Finally, the results were validated by superimposing data from 199 wells onto the categorized groundwater available zones, with the majority (76%) of the wells aligned with high and very high groundwater available zones. The validation demonstrates excellent groundwater predictability with an overall AUC value of 0.925.