| Yilong Lake is the smallest lake in Yunnan"s nine plateau lakes, with the least water storage, the shallowest water depth, the most prominent contradiction between human and land, and the most serious eutrophication. Under the dual threats of global climate change and human activities, it is increasingly facing many problems such as water shortage, difficulty in water pollution control, and how to balance protection and development. Based on the long-series hydrological, meteorological, water quality and land use data from 1992 to 2024, this study systematically reveals the evolution law of the water environment of Yilong Lake and its driving mechanism by combining Spearman correlation analysis and machine learning algorithms (Extra Trees). The results show that: (1) the water quality of Yilong Lake is classified as Class V to Class V, with obvious interannual fluctuations. The comprehensive nutrient status index (TLI) of the water body is 56-80, and it is generally at a light to severe eutrophication level; (2) the lake water level and water storage are significantly negatively correlated with the TLI of the water body (correlation coefficients are -0.734 and -0.633, respectively, p < 0.01). Water resources are the core factor causing the fluctuation of water quality in Yilong Lake; (3) based on the constructed TLI and land use ratio response model, the nonlinear impact of land use change on the water quality of Yilong Lake was quantitatively analyzed. The expansion of construction land, the increase of economic forests, and the reduction of grassland and water area are the main causes of eutrophication of the water body in Yilong Lake; The research results provide a reference for eutrophication control and water ecological restoration of plateau shallow lakes such as Yillong Lake. |
