基于SWAT-WASP耦合的东洋河流域水质分析

Water quality analysis of Dongyang River basin based on the SWAT and WASP coupled models

为分析东洋河流域的水质状况,利用SWAT-WASP松散耦合模型对东洋河各子流域及其河道的氮污染负荷进行了模拟。通过SWAT模型模拟污染负荷的分布情况,分析不同土地利用类型及坡度等级对氮负荷的影响,并将SWAT模型氮负荷量及月流量的输出值作为WASP模型污染负荷的输入值,以实现SWAT-WASP模型的松散耦合,进而完成对东洋河河道氮污染负荷的模拟。从SWAT模型结果分析,耕地、居民用地污染负荷较大,是流域氮污染负荷的主要来源。通过SWAT-WASP耦合对河道水质状况进行分析可知,勃塘沟支流水质情况最差,总氮、有机氮污染浓度最高,且41号河段入库浓度指标均高于Ⅲ类水标准要求。

To assess the quality of the river water of Dongyang River basin through the loose coupling between the SWAT and the WASP models,the present paper has made a simulation on the non-point source pollution loads. To achieve the purpose,we have tested the watershed segmentation function of the SWATWASP model,which candivide the whole river basin into 11 sections. And,then,the emissions from the pollution of the nonpoint sources can be taken asthe input into the SWAT model to establish the basin pollution load module. And,so,we have simulated the pollution loads of each branch of theriver by analyzing the effects of the different land use types and slope grades on the nitrogen pollution loads. The results of the output of the nonpoint source pollution loads and the monthly emissions of SWAT can be taken as the boundary condition input volume of the Wasp model. And,thirdly,we have simulated the nitrogen pollution loads of the river with the WASP model to analyze the water quality in the river sub-basin and the river channel by tracing the effects of the land use types on the nitrogen pollution load in the basin area. The results of the testing of the pollution loads of the cultivated land and the residential areas from SWAT model help us to notice that the pollution there is more serious and thereforecan be taken up as the main source of the nitrogen pollution loads. However,from the point of view of the slope grade,the nitrogen pollution load proves not obvious in the said area,for the total nitrogen loads with the slope turn tobe different among the diverse land use types. Thus,the analysis of the river water quality through the SWAT-WASP coupling indicates that the concentration rate of the organic nitrogen tends to increase gradually from the upstream to the downstream. And,of all the likely pollutant sources,the water quality of the branch of Botanggouprove to be the worst,for its concentration rates of the total nitrogen and organic nitrogen turn out to be highest or most serious,whereas the water quality of the Liangjiawan tributariesproves to be the best. Therefore,the water quality changing situation of the total nitrogen concentration rates in the main stream of Dongyang River prove to beinsignificant.