Relationship between Water Use and per Capita Income with Environmental Kuznets Curve of Developing Countries: A Case Study in Jiangsu Province, China

The relationship between economic growth and environmental variation is an important issue of sustainable development for human beings, especially in developing countries. However, developing countries usually use the standards of developed countries when dealing with environmental issues, which makes the relationship exhibit different characteristics than it does in developed countries. In order to realize a balance relationship between water use and income per capita in developing countries, a multivariable environmental Kuznets curve (EKC) simulation model based on the grey absolute correlation method was modified to improve the description of the balance relationship between water use and per capita income in the Jiangsu Province of China from 2005 to 2017. The results showed that the industrial and agricultural water uses first increased and then decreased, which agreed with an inverted “U” characteristic. The industrial water use was in the declining stage of the inverted “U” characteristic, while the agricultural water use was in a transition phase of the inverted “U” characteristic. However, the domestic water use showed an increasing trend, and it is difficult to estimate whether it showed an inverted “U” characteristic. Simultaneously, different watershed partitions in Jiangsu Province presented different EKC characteristics. In the three different watershed zoning regions of Jiangsu Province, the total water use of the Tai Lake Basin and the Yangtze River Basin exhibited the typical inverted “U” characteristic, while the Huai River Basin was just in the increasing stage. Moreover, the improved multivariable EKC model was suitable to describe the inverted U-shaped variation characteristics of water use, and the developed model outperformed the univariate EKC model in the study area. Based on the characteristics of the EKC, policy ideas for enhancing the coordination among water resources, the economy, and the ecological environment were proposed in order to achieve sustainable development.