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Abstract

Climate change and Land Use/Land Cover (LULC) change have significantly affected the ecosystem, livelihood, natural hydrology, and water resources of millions of people in the world. The Blue Nile (BN) river basin has experienced a substantial change in the LULC in recent decades, resulting in flow regime alterations. For example, the forest cover in the basin declined by 24% between 2000 and 2020. We designed different experiments with dynamic/static LULC, future LULC, and climate projections to assess the potential impacts of the LULC and climate change on the water availability in the BN river. These scenarios were evaluated using Soil and Water Assessment Tool (SWAT), which was calibrated using streamflow at four stations. To study the role of LULC, three modeling scenarios were generated for LULC 2005 & 2015 (dynamic), 2010 (static), and 2030 & 2050 (future) using the Terrset tool. To investigate the climate change impact on the BN river CMIP6 GCMs ensemble data was used under two scenarios, SSP45 and SSP585. The SWAT model performance and uncertainty were examined using SUFI-2 algorithm of SWAT-CUP. The model results showed NSE values varying between 0.67-0.84 and 0.65-0.80 for Calibration and validation, respectively, at the four stations. The modeling experiments revealed significant variations in water balance components (groundwater & surface water) under different LULC and climate scenarios. The study highlights the potential impacts of these factors on regional hydrology and water availability, emphasizing the need to consider them in water resource planning and management in the BN river basin.