Spatiotemporal Dynamics of Groundwater Recharge and Water Yield in the Wabe River Catchment, Western Margin of the Main Ethiopian Rift (MER), Omo-Gibe River Basin, Ethiopia

Groundwater recharge and water yield are increasingly threatened by land-use/land-cover (LULC) change and climate variability, yet their combined effects remain poorly quantified in data-scarce regions. This study assessed the spatiotemporal responses of groundwater recharge and water yield to historical and projected LULC transitions and climate change in the Wabe River catchment, located along the western margin of the Main Ethiopian Rift, Ethiopia. The eco-hydrological Soil and Water Assessment Tool (SWAT) was used to simulate hydrological processes for historical (1986–2022) and future (2026–2085) periods. Future LULC patterns were projected using an integrated Multi-Layer Perceptron–Cellular Automata–Markov chain (MLP-CA-Markov) modeling framework, while climate change impacts were evaluated using an ensemble of regional climate model projections under Representative Concentration Pathway (RCP) 4.5 and RCP8.5 scenarios. Results show that historical LULC conversion, mainly from natural vegetation to agriculture and built-up areas, reduced groundwater recharge and water yield by up to 3.4% and 2.9%, respectively. Projected LULC scenarios for 2041 and 2058 suggest further decreases of up to 3.3% in recharge and 1.0% in water yield. Under climate change alone, simulations based on RCP4.5 project groundwater recharge losses of about 22% and water yield declines of 26% by the mid-century period, while RCP8.5 scenarios foresee even greater reductions-up to 31% and 36%, respectively. The interaction between LULC and climate change amplifies hydrological variability, underscoring the vulnerability of groundwater-dependent systems in volcanic terrains. These findings highlight the urgent need for integrated land and water management policies that promote sustainable land use, strengthen climate adaptation, and enhance catchment-scale groundwater resilience.