Driving effects of ecosystems and social systems on water supply and demand in semiarid areas

Climate and socioeconomic changes have led to increasing severe water scarcity in arid areas, which has aroused widespread concern. However, the impacts of drought and ecological water replenishment on water scarcity have been largely ignored, and there is a lack of systematic understanding of the linkages among water supply and demand, ecosystems and social systems. Using western Jilin Province, China, a typical semiarid area, as the study area, this study quantified water supply and demand and measured water scarcity under average, drought, and ecological water replenishment conditions from 2000 to 2020; built network structures among water supply-demand, ecosystems, and social systems; and predicted future changes in water scarcity risk from 2020 to 2040. The results revealed that drought decreased the water supply by approximately 27%, whereas ecological water replenishment increased the water supply by approximately 30%. Land use/land cover change had a small effect on the water supply (less than 3%) but a large effect on the water demand (approximately 16%-38%). Drought exacerbated water scarcity in 3.14%-10.93% of the region, whereas ecological water replenishment decreased water scarcity in 5.46%-6.31% of the region. Precipitation, population density, and gross domestic product were the important factors connecting water supply and demand, and the normalized difference vegetation index was always the key factor connecting water supply, demand, and supply-demand match. Droughts weakened, but ecological water replenishment strengthened the connections among water supply-demand, ecosystems and social systems. From 2020 to 2040, drought further exacerbated the scarcity risk, while water scarcity occurred under ecological water replenishment conditions. Ecological water replenishment needs to be strengthened, and it is necessary to consider the demands of different stakeholders to achieve win-win results. This study can inform sustainable management strategies for agricultural production and water resources in arid areas.