Dynamic Water Environment Capacity Assessment Based on Control Unit Coupled with SWAT Model and Differential Evolution Algorithm

Water pollution is a serious problem in China and abroad. Revealing the source types their spatio-temporal characteristics premise of effective watershed management prevention. Since national control unit can better match administrative division, it was useful for manager to water pollution. Taking Fenhe River Basin as research area, SWAT model based on established this study reveal current situation quantity quality. Then, combination with differential evolution algorithm, dynamic environment capacities each were further discussed. The results showed that flow upstream lower, only 7.62–8.40 m3/s, but midstream downstream increased 17.58 m3/s 18.32 m3/s. Additionally, tributaries generally lower than main stream, 6 11 0.23 0.62 quality could meet requirements drinking sources, most after passing through Taiyuan City, concentration NH3-N TP reached 6.75 mg/L 0.41 mg/L. environmental capacity residual ammonia nitrogen (NH3-N) total phosphorus (TP) stream positive, indicating accommodate load general, there an obvious difference different months year. Especially wet season, non-point (NPS) more prominent, resulting high-capacity consumption rate. It Taiyuan, Jinzhong, Linfen Yuncheng Shanxi Province, should be wary In addition, units also varied greatly. Section highest, which mainly occurred season. negative values −131.3 tons/month −12.1 tons/month. Moreover, 21–40% whole year addition impact NPS due point pollution, 8, 9, 10 had high dry especially January February. construction analysis provide technical support realize accurate control.