Evaluation on the effect of water environment treatment –A new exploration considering time based on the RCS

The River Chief System (RCS), an innovative top-down and bottom-up water resource management system in China, is implemented to manage increasingly complex water environment issues. However, there has been a time lag in policy implementation. To accurately and scientifically assess the effect of RCS, a dynamic multiple-attribute decision-making method considering the time factor (DMADM) has been proposed. We have constructed the model consisting of 17 indicators from four aspects and determined the index weights and time weights by using the gray relation analysis method, the maximum entropy principle, and the subjective empowerment method. Finally, we applied the model to evaluate the water environment governance effect in the Taihu Basin from 2008 to 2020. The results have been ranked by possibility degree matrix, showing that: (1) The water environment in Taihu Basin maintains a steady improvement trend until 2014, except in Jiangsu Province;(2) The ranking result of the final comprehensive evaluation value is Shanghai ([0.334, 0.376]) ≻ Zhejiang ([0.316, 0.353]) ≻ Jiangsu ([0.305, 0.336]). Shanghai is far ahead with systematic pollution control measures, while Jiangsu lags due to the large fluctuation of pollutants (COD, NH3-N) in the wastewater. The study finds that the water environment management in Taihu Basin did improve over the past years, but failed to achieve the RCS governance goals at each stage. Enhancing coordination and cooperation and improving supervision mechanism for precise governance can better consolidate the results of RCS governance.