Coupling coordination degree between social-economic development and water environment: A case study of Taihu lake basin, China

Exploring the coupled and coordinated development of social-ecological systems is an important basis for promoting integrated watershed management. Based on the framework of the social-ecological system of lake water environment governance, this study builds an evaluation index system for quantifying the coupling and coordination of the social-ecological system, selects the representative key variables in each component of the social-ecological system, and evaluates the coupling and coordination changes in the social-ecological system of Taihu lake water environment governance from 1987 to 2020. This study uses the coupling coordination degree model (CCDM) and the obstacle degree model (ODM) to reveal the dynamic relationship between the coupling degree (CD), the coupling coordination degree (CCD), and their obstacle factors of the social-ecological system of lake water environment governance. The results show that: (1) The comprehensive social system development level shows an uptrend, while ecological subsystem shows a decreasing and then increasing trend. With the development of social economy, water environment has experienced the process of deterioration followed by recovery. (2) CD and CCD both show a downward trend first and then an upward trend. CD ranges from 0.71 to 0.98, its status had fluctuated between high-quality coupling stage and break-in stage. CCD ranges from 0.42 to 0.58, its status had fluctuated between near maladjustment recession and critical coordination stage. (3) The average obstacle degrees of the ecosystem and the social system are 0.51 and 0.49, the strong human activity interference in the social system and the vulnerability of the ecosystem and uncertainty jointly affects the CCD. Therefore, to improve the CCD of the social-ecological system of lake water environment governance, it is recommended that attention should be paid to the use and treatment of water resources in the process of social and economic development of the basin, and the amount of external pollution into the lake should be controlled in many ways. This study can help to understand the coupled social-ecological system interactions of Taihu lake water environment governance and provide a scientific basis for decision-makers.