基于SWAT模型祖厉河流域非点源污染优先管理区识别研究

Research on the Identification of Non-Point Source Pollution Priority Management Areas in the Zuli River Basin Based on the SWAT Model

为识别祖厉河流域非点源污染优先管理区,基于SWAT模型选取黄河一级支流祖厉河流域为研究对象,研究首先模拟出流域非点源总氮污染负荷空间分布情况,以及分别从年际和月际变化角度分析流域总氮负荷变化;并考虑子流域上下游关系及河道对于污染物的滞留作用,以流域黄河汇入口为水质影响监测点,根据子流域相对于整个流域的总氮污染强度,进行非点源污染优先管理区的划分。结果表明:SWAT模型在祖厉河流域适用,利用SWAT-CUP软件针对径流和水质的模拟值进行参数率定,其纳什效率系数均高于0.5。由模拟结果可以得出,各子流域总氮负荷相差较大,位于上游的子流域总氮负荷较小,而负荷较大的子流域,主要分布在河流出口处;自2001-2022年的20年间,整个流域的总氮负荷的变化趋势与年降水量的变化大致相同;并且季节性变化明显,在夏季总氮负荷最高。根据总氮污染强度,将子流域划分为三类污染优先管理区,通过对比发现,在20年间流域中需要对非点源污染优先管理的子流域,大致沿祖厉河上游的苦水河主河道由南致北纵向分布。该成果可为祖厉河流域非点源污染治理及生态修复与保护工作提供参考。

In order to identify the priority management area of nonpoint source pollution in the Zuli River basin,the Zuli River basin,a firstclass tributary of the Yellow River,was selected as the research object based on the SWAT model.The study firstly simulated the spatial distribution of total nitrogen loads from nonpoint sources in the basin,and analyzed the change of total nitrogen loads in the basin from the perspective of the interannual and inter-monthly changes.The upstream and downstream relationships in the sub-basins and the role of the river channel in retaining the pollutants were considered.The Yellow River confluence in the basin is the water quality impact monitoring point.Based on the total nitrogen pollution intensity of the sub-basins relative to the entire basin,non-point source pollution priority management area were divided.The results show that the SWAT model is applicable in the Zuli River basin,and the Nash efficiency coefficients are higher than 0.5 using SWAT-CUP software for the simulation values of runoff and water quality for parameter rate fixing.From the simulation results,it can be concluded that there is a large difference in total nitrogen loads in each sub-basin,and the total nitrogen loads of the sub-basins located in the upper reaches of the basin are small,and those sub-basins with large loads are mainly distributed in the outlet of the river.From 2001 to 2022,the trend of total nitrogen load in the whole watershed was approximately the same as that of annual precipitation;and the seasonal change was obvious,with the highest total nitrogen load in summer.According to the intensity of total nitrogen pollution,the sub-basins were divided into three types of pollution priority management zones,and it was found that the sub-basins that need to prioritize the management of non-point source pollution during the 20-year period were distributed along the main channel of the Bitter Water River,which is the upper reaches of the Zu Li River,from the south to the north.The results can provide a reference for the management of nonpoint source pollution and ecological restoration and protection in the Zuli River basin.