Urban watershed ecosystem health assessment and ecological management zoning based on landscape pattern and SWMM simulation: A case study of Yangmei River Basin

Urban watersheds encounter a series of problems in the urbanization process, including water quality degradation, landscape space fragmentation, and ecological degradation. Ecosystem health assessment and ecological management zoning are prerequisites for ecological restoration and watershed sustainability. In terms of ecological integrity and ecosystem services, a watershed ecosystem health assessment framework was constructed in this study. In addition, ecological health indicators were obtained on a grid scale by introducing landscape pattern models, hydrological models, and ecosystem service proxy models. The ecosystem health assessment results of the Yangmei River Basin in 1999, 2013, and 2019 were determined via indicator weighted calculation. The ecological health levels and spatial patterns of different periods were simultaneously compared to analyze the reasons for the dynamic changes in the watershed ecological health. The results showed that due to the impact of human activities, the watershed ecosystem health changed drastically in the western mountains and the southeastern living area from 1999 to 2013. During 2013–2019, the urbanization process triggered changes in the landscape structure, while watershed ecosystem services value increased, and the deterioration of the watershed ecosystem health slowed down. Overall, the watershed ecosystem health has deteriorated in the past 20 years, and the regional differentiation was enlarged. Based on the dynamic changes in the watershed ecological health, five ecological management zones were obtained to help decision-makers formulate reasonable urban watershed ecological restoration plans, ensuring long-term sustainable ecosystem services.