Spatial-based mapping of the groundwater potential zones of Akaki catchment in the surrounding highlands of Addis Ababa, Ethiopia

Human activities and climate change are hindering water supply in the Akaki catchment. This issue is aggravated by the reduction in groundwater levels due to excessive withdrawal. Hence, this study investigated the potential groundwater areas within the catchment by considering eight different factors. Eight thematic map layers were created utilizing ArcGIS. The analytical hierarchy process (AHP) was conducted using the geospatial monitoring and modeling system software (i.e., TerrSet- v.19.0.6). Through the analysis, it was determined that lithology (31%), rainfall (23%), lineament density (18%), drainage density (11%), slope (6%), land use (4%), soil (4%), and elevation (3%) exhibit their respective degrees of significance on groundwater potential in the catchment. Pair-wise computations showed an acceptable range, displaying a consistency ratio below 0.1. Subsequently, a weighted overlay analysis was done and it revealed that approximately 41% of the catchment area is situated in the Northeast, Central, and Northwest regions characterized by moderate groundwater potential. Also, about 43% of the catchment, located in the Northwest, Central, and Southeast regions, shows a high groundwater potential. In the southern part, an area covering approximately 15% of the catchment, has been identified as having a very high groundwater potential. Furthermore, single-parameter sensitivity analysis indicated that lithology, rainfall, and lineament were the parameters unveiling the highest sensitivity. Finally, the results were validated by superimposing data from 199 wells onto the categorized groundwater potential regions, indicating that the majority (76%) of the wells aligned with high and very high groundwater potential zones. Additionally, the validation demonstrates excellent groundwater predictability with an overall AUC value of 0.925. Therefore, the study underscores the importance of gaining a deep understanding of the factors influencing groundwater potential within the catchment to plan a sustainable supply of groundwater resources.