Exploring spatiotemporal heterogeneity and driving factors of water supply and demand in the Jialing River Basin from the perspective of service flows

Abstract

With ongoing population growth and continuous urbanization, the mismatch between the supply and demand of water ecosystem services is becoming increasingly severe. Building connections between humans and nature through service flows can clarify the pathways of water resource supply and demand. Therefore, this study employs the Soil and Water Assessment Tool (SWAT) model to quantitatively analyze the supply and demand of water in the Jialing River Basin (JLRB) from 2000 to 2020. It constructs a spatial flow model of watershed water ecosystem services and evaluates the watershed water security index (WSI). The results indicate that the total water resources in JLRB generally showed a surplus over the three years analyzed. The static WSI were 0.2204, 0.2134, and 0.2116, with notably higher values in the eastern region compared to other areas. Considering water resource flow, 5 %–15 % of sub-basins met their water demand after receiving upstream supplies, significantly improving water security. However, the annual WSI shows a declining trend, decreasing from 0.7582 to 0.7468. The primary driver of the WSI decline is evapotranspiration (ET), though its explanatory power has weakened, with anthropogenic factors having an increasing impact. It is recommended that local governments strengthen the management and oversight of human water use. This study comprehensively and accurately represents the flow pathways of water resources and the supply-demand mismatch. This not only provides decision-making information for formulating appropriate policies in different regions but also lays the foundation for promoting the healthy development of ecological security patterns in the future.