Identification and Mapping Groundwater Potential Zones Using Geospatial Analysis for Genale-Dawa Bale Sub-Basin, Oromia, Ethiopia

Groundwater is one of the most crucial natural water supplies because of continuously directly or indirectly supports many domestic, agricultural, and industrial activities but is now being degraded due to various causes. <i>Therefore, this study aimed to iddentfy and map the factors that determine groundwater potential and produce a groundwater potential zones map for Genale-Dawa Bale Sub-Basin.</i> Accordingly, in this study, ten (10) factors affect groundwater potential at varying degrees namely: rainfall, geomorphology, LULC, lithology, soil texture, slope, elevation, topographic wetness index, drainage, and lineament density were used. Criteria weights and rankings were assigned based on expert opinion, literature review, and field survey experience, using Analytical Hierarchy Process (AHP) and ArcGIS 10.3 software to map potential groundwater zones. The results show that thematic factors such as rainfall, geomorphology, LULC, lithology, soil texture, slope, topographic wetness index, elevation, drainage density, and lineament density affect groundwater potential with weight values of 24.2%, 18.7%, 10.7%, 13%, 7.9%, 6.9%, 3.8%, 3.8%, 5.4%, and 5.7% respectively in the study area. Maps of groundwater potential zones classified into five categories: very low 366,001.80 ha (24.36%), low 249,151.07 ha (16.58%), moderate 271,817 ha (18.09%), high 278,343.13 ha (18.53%), and very high 337,194.06 ha (22.44%) for the Bale Zone and the Genale-Dawa Sub-Basin. The low to very low groundwater potentiality has been seen on the map at different distances due to the presence of hills and steep slopes, rock outcrop surfaces, clay soil textural class, low rainfall areas, very high drainage density, low lineament density, bare land are the main reasons. The validation analysis revealed a 91% confirms the very good agreement between the groundwater inventory data and the developed groundwater potential zone. The groundwater potential zones assessment and map of the current research results serve as a baseline information for planners, decision-makers, and adopters of sustainable management options, to identify suitable sites for groundwater exploration, and initial for further studies. Further studies, detailed water chemistry surveys, geophysical surveys at potential drilling sites, and grade analysis should recommended.