Analysis of Pollution Load and Accurate Assessment of Ecological Capacity in Tianmu Lake Basin Based on Target Control

This study evaluated the ecological capacity of Tianmu Lake and analyzed its water environment and pollution load using a distributed hydrological model (SWAT) with high spatial resolution and long time series. The findings indicated significant interannual variations in total phosphorus (TP) and total nitrogen (TN) loads, with high flow years exhibiting substantially higher levels (TP: 6.69 tons year^-1, TN: 328.85 tons year^-1) compared to low flow years (TP: 4.61 tons year^-1, TN: 210.69 tons year^-1). Monthly loads were elevated during wet and normal seasons, with spatial concentrations in the Zhongtian River basin and the Yangzhuang River basin. To achieve water quality targets for 2025, 2030, and 2035, TP and TN reductions are needed in the Shahe and Daxi Reservoirs. The study emphasizes the importance of integrated strategies, including spatial optimization, source reduction, and transport regulation, to enhance ecological capacity and mitigate pollution concentration.