Evaluation of groundwater recharge potential using geospatial analysis in the Ziway lake watershed, Ethiopian Rift: A GIS and AHP-Based methodological framework

Groundwater is an indispensable resource; however, its highly variable distribution in space and time presents significant challenges in identifying and mapping reliable sources. This challenge is particularly evident in the Ziway Lake watershed (ZLW), situated within the Main Ethiopian Rift (MER), characterized by complex hydrogeology, featuring diverse geological formations, varying soil properties, and inconsistent rainfall patterns. Therefore, this study aims to identify and prioritize groundwater recharge potential zones within the ZLW to support sustainable groundwater management by integrating geographical information systems (GIS)and the analytical hierarchy process (AHP) methods. Key factors, including rainfall, lithology, elevation, lineament density, slope, land use/land cover, soil texture, normalized difference vegetation index, evapotranspiration, and drainage density, were analyzed using GIS. AHP was employed to assess the relative importance of these factors, and GIS based overlay analysis was applied to produce recharge potential zone map, which was validated through Receiver Operating Characteristic curve analysis. The results identified five groundwater recharge zones: Very low (18.05 %), low (23.61 %), moderate (21.89 %), high (19.64 %), and very high (16.81 %). Over 58 % of the watershed exhibits moderate to very high groundwater recharge potential, highlighting critical areas for groundwater resource management to address environmental challenges. The sensitivity of the factors utilized was assessed, showing that rainfall and lithology are the most essential factors controlling groundwater recharge potential in the region. This study provides insights for water resource policy and planning for Ethiopia's Green Legacy Initiative by identifying afforestation sites, and promotes environmental sustainability and climate change adaptation strategies at local and global scales.