基于SWAT模型的北京密云水库沿湖区氮磷流失风险分区

Identification of the risk area of nitrogen and phosphorus loss at lakeshore of Miyun Reservoir by using SWAT Model

识别流域氮磷流失风险区是高效控制农业非点源污染的重要前提。本研究基于校正和验证后的SWAT模型,在模拟区域氮磷流失负荷的基础上,参考水质控制标准,对密云水库上游沿湖区氮磷流失风险区进行划分。结果表明:密云水库沿湖区地表饮用水质磷指标良好,总磷流失风险处于优质饮用水区和一般饮用水区2个风险水平,均达到地表饮用水标准。但总氮流失需要加强重视,总氮的一般饮用水区为地表饮用水标准的Ⅲ级,占总面积的50.42%;风险饮用水区为地表饮用水标准的IV和V级,占总面积的49.58%,未达到饮用水标准。总氮风险区主要分布在石城乡、高岭镇和北庄乡,与潮河段、小汤河段、/牛河下游一起,应加强对区域氮素流失的治理。

Identification of risk areas of nitrogen and phosphorus loss is essential for the effective and efficient implementation of watershed management programmers.In this study,a calibrated Soil and Water Assessment Tool（SWAT） model was verified and used for identification critical sub-watersheds of nitrogen and phosphorus loss at the lakeshore region of Miyun reservoir based on the national drinking water standard.The results showed that the total phosphorus content in the surface runoff were all fell under the drinkable class,which indicated a low risk of phosphorus loss at all the lakeshore region of Miyun Reservoir.However,the total nitrogen content fell down to undrinkable level covered 49.58 percent area of the sub-basins.The risk sub-basin with high total nitrogen losing were mainly located at Gaoling town,Beizhuang town,and Chaohe reach,Xiaotanghe reach,lower reach of Mangniuhe.These risk regions were proposed as critical area for more effective control of the nitrogen loss.