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Abstract. The dynamic evolution pattern of regional water supply-demand risks under the combined effects of climate change and human activities remains unclear, particularly against the backdrop of agricultural expansion in arid regions. This study focuses on the Tailan River Basin (TRB), a typical arid watershed in China and a vital base for high-quality fruit and grain production. By integrating the PLUS (Patch-generating Land Use Simulation) and InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) models, we constructed a water supply-demand risk assessment framework encompassing 24 climate-land change scenarios to quantify their impacts on regional water resource patterns and risks. Results reveal that climate change profoundly influences water supply, while land use significantly affects water demand. Under the Balanced Economic and Ecological Development Scenario (BES), 531.2 km2 of additional cultivated land could be developed by 2050. However, this cultivated land expansion leads to a sharp increase in irrigation water demand, with the minimum demand reaching 4.87 × 108 m3, while the maximum regional water supply is only 0.16 × 108 m3, resulting in a significant supply-demand gap (> 4.71 × 108 m3). The risk assessment framework indicates that by 2050, the entire TRB will face a water supply-demand crisis, with at least 46 % of the area experiencing severe (Level III) or higher risks. The study demonstrates that continuous cultivated land expansion driven by agricultural activities – which drastically increases irrigation water demand – is the root cause of intensifying water supply-demand conflicts and high risks in the TRB. By 2050, the proportion of irrigation water to total water use will exceed 70 %, regardless of scenario. These findings underscore the necessity of deeply integrating multidisciplinary approaches within a water risk framework to elucidate land-eco-hydrological feedback mechanisms and better address water security challenges under climate change. The results provide a scientific basis for optimizing regional water-land resource allocation and promoting agro-ecological sustainable development.
You et al. (Tue,) studied this question.