Projected Impacts of Climate and Land Use/Land Cover Change on Sediment Yield and Surface Runoff in the Baro River Sub-Basin, Ethiopia.

Understanding how climate change and land use/land cover (LULC) dynamics influence watershed hydrological processes is essential for achieving sustainable water and land management, particularly in data-scarce and erosion-prone basins. This study assesses the individual and synergistic effects of CMIP6-based climate projections and LULC change on sediment yield and surface runoff in the Baro River sub-basin. Utilizing a comprehensive hydrological modeling framework, this study integrates the Soil and Water Assessment Tool (SWAT) with CMIP6 multi-model ensemble climate projections under SSP2-4.5 and SSP5-8.5 scenarios to simulate runoff in addition to sediment yield. We projected future LULC dynamics (2024-2064) using a multi-layer perceptron-cellular automata-Markov chain (MLP-CA-MC) model. Results indicate statistically significant warming in both historical and future periods, with mean temperature increases of up to 3.4°C under SSP5-8.5, alongside precipitation increases of 6%-13%. LULC projections (2024-2064) indicate an 18%-26% increase in agricultural and settlement areas at the expense of forest, grassland, and shrubland. The SWAT model demonstrated high predictive accuracy; Nash-Sutcliffe efficiency (NSE) values remained strong across both calibration (runoff: > 0.87; sediment: > 0.76) and validation (runoff: 0.84; sediment: 0.73). Projected sediment yield increases from a 2024 baseline of 49.23 t/ha to as high as 157.68 t/ha over the late period (2072-2100) under the SSP5-8.5 scenario with 2064 land use conditions. Similarly, surface runoff is expected to peak at 966.58 mm under high-emission conditions. These results highlight the critical sensitivity of the Baro River sub-basin to both climate variability and anthropogenic land degradation, underscoring the urgent need for integrated watershed management to mitigate downstream sedimentation and ensure the sustainability of water infrastructure.