Spatial-temporal variation characteristics and coupling coordination of the "water resources - water environment - water ecology" carrying capacity in the Three Gorges Reservoir Area

The coordinated control and management of water resources, the water environment, and water ecology are essential for optimizing the management of water resources, improving the water environment, rehabilitating water ecosystems, and achieving sustainable development. Most studies conducted to investigate the water carrying capacity have focused primarily on water resources or water environment. However, it is challenging to conduct such research in areas where the interactions between water resources, the environment, and ecology are intricate. In this study, an evaluation indicator system for the water resources - water environment - water ecology carrying capacity (WCC) was constructed, and a coupling coordination model and GeoDetector were employed to systematically analyze the coupling coordination indices (CCI) among the water resource carrying capacity (WRECC), water environment carrying capacity (WENCC), and water ecology carrying capacity (WECCC), as well as the main influencing factors in the Three Gorges Reservoir Area (TGRA) from 2005 to 2018. The results showed that the numbers of counties and districts with a high CCI class gradually increased over this period. The percentage of Class V fluctuated from 0% to 7.7%, and the stability of the water system steadily increased. Spatially, the overall distribution pattern gradually increased from southwest to northeast, and both the single and interactive effects of anthropogenic factors on water systems gradually increased. The CCI was predominantly affected by factors such as the amount of surface water resources per capita, indices of water conservation, forest coverage, discharge of domestic sewage per capita, and water replenishment of the ecosystem. These results show that coordination between the WCC components should be strengthened to further improve water use and domestic water treatment efficiency. To achieve superior-class, effective, and environmentally friendly scientific governance, the productivity of water resources should be increased in areas where the disparity between water availability and the demand for socioeconomic development is severe, and sewage treatment processes should be closely regulated. It is also important to combine resource development and utilization with water ecological protection and management.