Dynamic assessment of water resources carrying capacity under human impacts on the water cycle: A finer perspective at the spatiotemporal scale of basin

The water resources carrying capacity (WRCC) is an essential indicator for assessing the ability of water resources to support socioeconomic activities. However, existing studies on WRCC were inadequate in terms of both temporal and spatial resolution, and had not incorporated human activities such as water transfer and storage into their assessment process. In this study, a Soil and Water Assessment Tool (SWAT+) model was employed to examine the spatiotemporal variation of monthly water consumption overload in each subbasin of the Qinhuai River Basin (QRB), a basin that is significantly impacted by human activities, from 2021 to 2023. The water resources were allocated based on the connection among subbasins. Subsequently, a dynamic assessment of the WRCC in each subbasin was conducted before and after allocation using the entropy weighted technique for order preference by similarity to ideal solution (TOPSIS) method. The results show that the intraanual and interannual differences in water resources led to temporal variations of water consumption overload ratio (0.69-1.05) in QRB, while the differences in the water use structure of subbasins led to spatial variations of water consumption overload ratio (0.38-2.54). The water allocation could significantly increase the WRCC in the dry year from 0.43 to 0.47, and all the subbasins with a weak carrying status were improved to moderate, and in general lift the mean WRCC from 0.43 to 0.47. Finally, it is anticipated that the WRCC of QRB will continue to improve in the future under the SSP245 scenario, due to an increase in rainfall and a decrease in population size. This study discovers a finer relationship between human activities and water cycle in both temporal and spatial dimensions, and enhances the WRCC through water allocation, thereby providing a novel perspective on basin water resources management.