A Five-Dimensional Comprehensive Evaluation of the Yellow River Basin’s Water Environment Using Entropy–Catastrophe Progression Method: Implications for Differentiated Governance Strategies

The systematic evaluation of the water environment in the Yellow River basin is a critical scientific basis for achieving the goals of ecological protection and high-quality development. In this study, a five-dimensional comprehensive evaluation framework (“quality–quantity–space–flow–biota”) consisting of 19 indicators was constructed. The entropy method and the catastrophe progression method were innovatively combined to solve the limitations of traditional evaluation models in characterizing the nonlinear relationships within water environment systems. The results indicated that the Yellow River basin’s overall comprehensive water environment index was 0.032, classified as “good”. However, the spatial differentiation is significant, showing a step-by-step degradation characteristic of “upstream > downstream > midstream”. Gansu Province (0.028), Ningxia Hui Autonomous Region (0.026), Shaanxi (0.024), and Shanxi (0.020) were rated as “poor” and urgently need to be regulated. The core problems are water shortage (Gansu, Ningxia), water quality deterioration (Shaanxi, Shanxi), and fragmentation of aquatic space (Shanxi, Shaanxi). The findings of this study provided a quantitative tool for differentiated governance in the Yellow River basin which could directly support the decision-making needs of “zoning control and precise policy implementation” in the “Outline of the Plan for Ecological Protection and High-quality Development of the Yellow River Basin”.