River Ecosystem Health Assessment Based on Fuzzy Logic and Harmony Degree Evaluation in a Human-Dominated River Basin

River health assessment is a critical basis for river sustainable management. Taking the Neijiang River in the Chengdu Plain in Southwest China as an example, the health of the typical human-dominated river ecosystem was assessed combining point-river-basin scales. According to the connotation of river health, 16 indicators in 3 aspects, including habitat characteristics, biological communities, and social services, were selected to establish the assessment indicator system for river health. Field investigation, remote sensing, geographic information system, and environmental DNA were used to quantify the indicators. With the fuzzy comprehensive evaluation and harmony degree evaluation, the river system health was assessed, and the results showed that the health assessment index of rivers ranged from 0.73 to 0.85, indicating sub-healthy to healthy levels. The coordinated development level of the downstream is restricted by the comprehensive development level between ecological integrity and social service function. Furthermore, the main human activities were the construction of dams and changes in land use/cover in the study area. The spatial pattern of the river health assessment index indicated that the impact of human activities on river health was intricate. The river health evaluation framework proposed herein provided a tool for local river management and would apply to other human-dominated river basins.