Spatial and temporal evaluation of groundwater recharge using WetsPass-M model and remote sensing techniques in the Upper Omo-Gibe River basin, Ethiopia

For effective and long-term groundwater management, evaluating the temporal and spatial pattern of groundwater recharge is necessary, particularly in data-scarce areas like the upper Omo-Gibe River basin. The objective of this study was to evaluate groundwater recharge dynamics spatially and temporally using the GIS-based WetSpass-M model along with remote sensing techniques. Based on the model results, the long-term mean annual rainfall of the basin was divided into actual evapotranspiration of 903 mm (59%), surface runoff of 436 mm (28%), and groundwater recharge of 196 mm (13%). It was found in this study that soil types predominantly influence surface runoff, while land use has a significant influence on groundwater recharge and actual evapotranspiration in the basin. Therefore, sustainable management of groundwater resources should include a proper strategy for land use change that considers its effect on recharge. It is also essential to consider spatial and temporal variations in groundwater recharge rate when developing a sustainable groundwater resource management, planning, and development strategy for the upper Omo-Gibe River basin. This research introduces the novelty of utilizing the WetSpass-M model in the basin, which aligns well with its distinctive characteristics. The simulated results analysis confirms the model's effectiveness in assessing groundwater recharge and water budget components in the upper Omo-Gibe River basin.