Multi-criteria decision analysis and geospatial methods for identifying potential aquifer discharge zones in the upper Omo-Gibe River basin, Ethiopia

Groundwater potential regions in the upper Omo-Gibe River basin were identified using the geospatial and multi-criteria decision-making methods. The groundwater area delineations in the sub-basin were estimated by geology, slope, topographic wetness index, land use land cover, soil texture, lineament density, recharge, and distance from rivers. Multicollinearity tests conducted before layer combination confirmed that none of the eight thematic layers utilized in the research demonstrated collinearity problems. The identified groundwater potential regions within the basin are very high (15 %), high (24 %), moderate (30 %), low (23 %), and very low (8 %) groundwater potential regions. The predicted groundwater prospect map was validated via well yields using the receiver operating characteristic curve, extending an area of 79 %. The validation of the model result using specific capacity and transmissivity displays the correlation coefficients of R² 0.71 and 0.77, respectively. Moreover, the map removal sensitivity analysis indicated that recharge and geology are the most sensitive parameters of groundwater availability, with sensitivity indices of 2.5 % and 2.16 %, respectively. However, the topographic wetness index with a sensitivity index (SI) of −1.55 % is the least sensitive factor, exhibiting an insignificant impact on identifying the groundwater potential areas. The findings of an integrated approach are important for developing sustainable water resources management strategies in the basin.