Mapping Groundwater Potential Zones Using GIS-Based Analytical Hierarchy Processes Techniques in the Upper Dawa River Basin, Southern Ethiopia

Abstract

Groundwater is a vital freshwater resource and a critical water source to supply domestic, irrigation, and industrial demand. As the demand for drinking water increases globally, the need to evaluate the groundwater potential and aquifer productivity also increases. This study focused on mapping the groundwater potential zones in the upper Dawa Basin, Southern Ethiopia, using a Geographical Information System (GIS) based Analytical Hierarchy Process (AHP). This study considers seven factors influencing groundwater availability, recharge, and distribution: geology, lineament density, slope, land use/land cover, drainage density, soil types, and rainfall. The relative significance of each factor was determined using a pairwise comparison matrix, and the normalized weight of each factor was calculated based on the procedure used in the AHP approach. The weighted overlay analysis (WOA) tool in Arc GIS 10.8 was used to produce the final groundwater potential zones map. To validate the accuracy of groundwater potential zones relationship of well yield and the potential zones are assessed using the area under curve (AUC) approach. The study area is divided into five groundwater potential zones: very low, low, moderate, high, and very high, respectively, covering 0.26%, 45.9%, 8.8%, 16.34%, and 28.08% of the study area. The volcanic terrain in the north and northwest, the limestone terrain in the southeast, and small areas along streamlines in the basement terrain in the south are mapped as very high to high groundwater potential zones. On the other hand, a large portion of the basement terrain is marked by low to very low groundwater potential. To assess the accuracy of the prospective groundwater zones, the area under curve (AUC) approach was applied. AUC is equal to 0.834, signifying the reliability of the result and the strong predictive capability of the AHP method. The result of this study supports the efforts to provide sustainable water sources for vulnerable communities of the study area.