Integrated hydrological modeling of anthropogenic and climatic perturbations in the upper Jemma subbasin of the Upper Blue Nile Basin, Ethiopia

Abstract

Anthropogenically induced land use/land cover (LULC) transformations and accelerating climatic variabilities have emerged as pivotal forces reshaping the hydrological equilibrium of fluvial systems, particularly in ecologically sensitive basins. This study systematically interrogates the compounded ramifications of LULC dynamics and projected climate change on the hydrological response of the Upper Jemma Watershed an integral sub-catchment of the Upper Blue Nile River system. Employing the advanced QSWAT+ hydrological modeling framework within a GIS interface, the analysis integrates bias-corrected climatic projections under RCP 4.5 and RCP 8.5 scenarios alongside multi-temporal remote sensing-derived land cover datasets. The findings unveil an unequivocal intensification of surface runoff and streamflow due to expansive agricultural encroachment, juxtaposed with a discernible decline in evapotranspiration and soil water retention. Climatic perturbations, notably temperature elevation and precipitation attenuation, further exacerbate these trends, with pronounced seasonality in hydrological fluxes. Importantly, synergistic interactions between land cover transformation and climatic anomalies manifest in nonlinear hydrological alterations, amplifying peak flows and diminishing baseflows. This underscores the riverine system's heightened vulnerability and the necessity for integrated watershed management strategies that account for multifactorial hydrological stressors. The study provides a robust empirical and modeling basis to inform adaptive water governance within transboundary river basins susceptible to environmental transitions.