Evaluation of water resource carrying capacity in the middle reaches of the Yangtze River Basin using the variable fuzzy-based method

The middle reaches of Yangtze River Basin (MYRB) are rich in water resources, with a large number of rivers and lakes. However, in recent years, water resources from this basin are no longer sufficient to support the region's rapid economic development. This study established a model to evaluate the water resource carrying capacity incorporating water resources, population, and socio-economic data. The characteristic values of water resource carrying capacity were calculated using the variable fuzzy evaluation method in MYRB from 2005 to 2020. Although both population and GDP in the MYRB showed an increasing trend between 2005 and 2020, the water supply capacity increased and then decreased. The weights of each index for evaluating the water resource carrying capacity of perennial botanical gardens were as follows: degree of water resource development (0.311) > total water resources (0.24) >population density (0.156) >GDP per capita (0.097)> water resources per capita (0.077) >water supply per capita (0.064)> water resources per unit area (0.055). Furthermore, the water resource carrying capacity in the MYRB showed an increasing trend from 2005 to 2020. In 2020, the carrying capacity of water resources in Changsha, Jingmen, Xiangtan, Hengyang, Wuhan, Xiaogan, Nanyang, and Xiangyang was attributed an evaluation grade of level 3, which indicates that the development and utilization of water resources in these areas were at their saturation point.