基于SWMM模型的沈阳典型小区非点源污染情景模拟

Simulation of non-point source pollution in a typical urban housing estate of Shenyang based on SWMM model

随着城市化发展,城市非点源污染占流域非点源污染比例不断增加,正成为研究的热点和难点。本研究基于实测和分布式水文模型SWMM结合方法,在3S技术的支撑下,以沈阳市典型居民小区为例,构建城市非点源污染负荷计算模型,并分析了不同降雨事件重现期和雨型条件下降雨径流及非点源污染负荷变化特征。结果表明,构建的SWWM模型精度较高,纳什效率系数(NSE)达到了0.7以上;TSS、TN、TP和COD的模拟精度较好,对重金属的模拟效果较差。降雨量增加对污染排放影响显著,降雨量由0.25年一遇增加到5年一遇,径流量增加了274.13%,同时TSS、TN、TP和COD分别增加了83.18%、119.37%、103.15%和78.07%;不同雨型降雨对污染浓度峰值产生过程存在影响,雨峰越靠前,污染物的峰值浓度越大。本研究结果能够对城市非点源污染负荷核算和海绵城市建设提供科学依据。

The proportion of urban nonpoint source （NPS） pollution in watershed NPS pollution is increasing with urbanization. Urban NPS pollution is becoming research hotspot. In this study, rainfallrunoff model was validated in a typical housing estate of Shenyang based on the measured data with the distributed hydrological model method （SWMM） to analyze the trends of rainfall runoff and urban NPS pollution under different recurrence intervals and rainfall types. The results indicated that the accuracy of runoff simulation was greater than 0.7. The total simulation accuracies of TSS, TN, TP, and COD loads were acceptable; however, the simulation accuracy of heavy metal was lower than that of nutrient pollution. Increased rainfall had a great influence on pollutant discharge. The runoff increased by 274.13% with the increase of recurrence interval of rainfall intensity from 0.25 years to 5 years. At the same time, the total emission of TSS, TN, TP and COD increased by 83.18%, 119.37%, 103.15% and 78.07%, respectively. For different types of rainfall, the earlier the rainfall peak appeared, the greater the peak concentration of pollutants happened. Our results provide a scientific support for urban NPS pollution estimation and sponge city construction.