Health Assessment of River Ecosystem in the Lower Jinsha River Basin Using an improved comprehensive fuzzy evaluation method

Abstract Cascade hydropower development significantly affects river hydrodynamics and water environments, posing substantial challenges to river ecosystem health. With ecosystem security emerging as a critical environmental concern, accurate health assessment of river ecosystem has become paramount for implementing precise restoration and management strategies. Current researches on river ecosystem health assessment are mainly focused on major river systems such as the Nujiang, Lancangjiang, Yangtze, and upper Yellow River, less on the medium and small rivers with intensive hydropower station. Moreover, existing studies usually focus on single dams and rivers, lack systematic evaluation frameworks, and neglect integrated watershed-scale analyses. This study presents an improved comprehensive fuzzy evaluation method to assess ecosystem health in the Jinsha River Basin. A assessment indicator system is developed, including four criterion layers (i.e., basin, water, biology, and social service), and five sub-criteria (i.e., morphological integrity, hydrological integrity, chemical integrity, biological integrity, and social service sustainability) for evaluating the Yibin section's river ecosystem health. Result shows that the comprehensive ecosystem health assessment results for eight rivers in the Yibin section of Jinsha River Basin presents a healthy ecological status. Sub-criterion evaluation revealed distinct performance variations, with morphological integrity showing relatively poorer conditions (average score of 69.98) compared to notably higher chemical integrity (average score of 91.5). Based on these ecosystem health assessment findings, the study further identified key influencing factors affecting river ecosystems in the Yibin section and developed targeted conservation strategies and management recommendations.