• • Under SSP119, desert area decreases by 0.69% by 2050, while under SSP585 it expands by 5.7%, with grassland loss of 23.0%, highlighting divergent land degradation pathways under climate policies.
• • Water yield under SSP119 reaches 147.6×10^8 t by 2050, whereas SSP585 yields only 43.9×10^8 t, a 70% reduction, underscoring the severe impact of extreme climate on water availability.
• • Precipitation and DEM are the primary drivers of water yield spatial distribution, with their interaction (land use × precipitation) exerting the strongest influence, indicating that land management can modulate water yield by up to 23%.
• • The south-high, north-low water yield pattern persists across scenarios, with high-yield zones confined to glacier and high-altitude areas, emphasizing the critical role of mountainous recharge in arid basins.