Comparative groundwater potential mapping using AHP and FR methods in the Woleka River sub-basin, Ethiopia

Abstract

Groundwater is Ethiopia's primary source of freshwater, making it essential to identify new groundwater resource zones to enhance water supply coverage. This study aims to pinpoint potential groundwater zones in the Woleka River sub-basin using analytical hierarchy process (AHP) and frequency ratio (FR) methods. Eight thematic maps including geomorphology, geology, lineaments, soil, rainfall, land use/land cover, drainage density, and slope were analysed using GIS, PSI Geomatica Banff, SAGA, and ERDAS imaging software. Receiver operating characteristic (ROC) and area under the curve (AUC) analyses were conducted to evaluate the predictive accuracy of the methods. The FR method has higher AUC (0.94) compared to the AHP method (0.83), indicating best effectiveness in groundwater potential mapping. Groundwater potential was categorized into five zones: very poor (5.7%), poor (48%), moderate (22.8%), good (22.8%), and very good (0.8%) based on the results of the FR method. Using AHP approach, the groundwater potential were classified in four zones: poor (5.6%), moderate (50.1%), good (44.2%), and very good (0.1%) of the study area. Areas with good to very good groundwater potential were highlighted for further exploration. This study may be of use for decision-makers, water developers, managers, and groundwater users in the region.