Comprehensive Evaluation of Yishui Happy River Based on GRA-TOPSIS Model

[Objective] We constructed an evaluation system for Happy Rivers tailored to the characteristics of small and medium-sized rivers in Jiangxi Province, and quantitatively evaluated the happiness level of Yishui River from 2019 to 2023 using an innovative comprehensive evaluation model. The study aims to provide a scientific basis for the construction of Happy Rivers and Lakes in Yishui River and similar river basins in Jiangxi Province, while verifying the applicability of the combined evaluation model for assessing the water environment of small and medium-sized rivers. [Methods] Guided by the framework for constructing Happy Rivers and Lakes in Jiangxi Province, we developed a three-layer system of “target layer - criterion layer - indicator layer” and selected 18 indicators, such as the compliance rate of flood control standard and the satisfaction degree of ecological base flow. The independence of the indicators was verified using correlation principal component analysis. To overcome the limitations of single weighting methods, the “BWM-EWM-minimum entropy” combined weighting method was employed to balance theoretical importance and actual data contribution. Integrating the advantage of GRA in describing dynamic trends with the comparative strength of TOPSIS in defining ideal states, this study calculated the Euclidean distance and grey correlation coefficient between samples and both the positive and negative ideal solutions to obtain the relative closeness and classify happiness levels. [Results] The relative closeness of the criterion layers for Yishui River was 0.418 9, 0.491 1, 0.547 3, 0.602 4 and 0.713 6 for the years 2019 to 2023, respectively, with an average annual growth rate of 14.04%. Compared to 2019, the relative closeness in 2023 increased by 1.7035 times, and the comprehensive happiness level improved from the qualified level of grade III in 2019 to the excellent level of grade I in 2023. These results indicated that Yishui River has achieved significant progress under the planning and construction of Happy Rivers and Lakes. From the perspective of each criterion layer, except for “enriching the people”, the relative closeness and happiness level of the other five criterion layers showed an increasing trend each year. The overall level of “enriching the people” exhibited an upward trend, improving from the qualified level of grade III in 2019 to the good level of grade II in 2023. “Enriching the people” emerged as the primary aspect affecting the happiness level of Yishui, and the development and utilization rate of water resources and water use per 10 000 yuan GDP were identified as key factors. [Conclusion] The construction of the Yishui Happy River and Lake has achieved remarkable results, but the dimension of “enriching the people” remains a bottleneck. Future efforts should focus on overcoming this bottleneck by strengthening water-saving management, developing water-related characteristic industries, and promoting regional cooperation. As the research data cannot reflect long-term change patterns, future studies should extend the monitoring period and improve the indicator system by incorporating county-level statistical data.