清水河流域农业非点源污染模拟及特征分析

为探讨冬奥核心区所在的清水河流域农业非点源污染特征,利用SWAT模型对清水河流域进行污染模拟及特征分析。通过前期对流域内河流水质监测和评价分析可知,该流域农业非点源是重要污染来源,且降雨和径流会对水质影响较大。借助ArcGIS平台构建清水河流域SWAT非点源污染模型,并利用实测径流数据对模型进行了率定和验证,结果表明SWAT模型在清水河流域的适用性较好。利用模型模拟结果对流域内TN、TP污染负荷进行统计,并对其时空分布特征展开分析。非点源污染的时间分布特征:2011、2013、2015和2016年的年均非点源污染输出负荷表现为TN>TP,并且具有明显的季节性,夏季和冬季分别是非点源污染产生的高峰期和低谷期,各子流域的累积负荷量也呈现出汛期大于非汛期的特点;空间分布特征:污染负荷流失强度较高的关键源区为2、3、5、6、7、10、12、14号子流域,集中分布在东沟和西沟水系两侧,主要土地利用类型为耕地和草地。各子流域的非点源污染输出负荷与降雨量均呈正相关关系,输出负荷与降水相关性较强的区域集中分布在正沟、西沟两侧和东沟上游,该区域内非点源污染物的流失与降水密切相关,高降雨量及强降水都会引起污染物的大量流失。

Simulation and Characteristic Analysis of Agriculture Non-point Source Pollution in Qingshui River Basin

In order to study the characteristics of agricultural non-point source pollution in Qingshui River Basin,the SWAT model is used to simulate and analyze the pollution characteristics.It can be seen from the monitoring and evaluation analysis of river water quality in the early stage,the agricultural non-point source is an important pollution source in the basin,and rainfall and runoff will have a greater impact on water quality.Based on the ArcGIS platform,SWAT non-point source pollution model of Qingshuihe river basin is constructed,and the model is calibrated and verified with the measured runoff data.The results show that SWAT model has good applicability in the basin.The TN and TP pollution loads in the basin are calculated and analyzed based on the simulation results of the model.The time distribution characteristics of non-point source pollution show that the annual output load in 2011,2013,2015 and 2016 was TN>TP,and obvious seasonality.Summer and winter are the peak and low periods of non-point source pollution respectively,and the cumulative load of each sub basin also shows the characteristics that the flood season is greater than non-flood season.The spatial distribution characteristics show that the key source areas with high intensity of pollution load loss are sub-basins 2,3,5,6,7,10,12 and 14,which are mainly distributed on both sides of Donggou and Xigou water systems,and the main land use types are cultivated land and grassland.The output load of non-point source pollution in each sub-basin has a positive correlation with rainfall.The areas with strong correlation between output load and rainfall are concentrated in Zhenggou,both sides of Xigou and the upper reaches of Donggou.The loss of non-point source pollutants in this area is closely related to rainfall.High rainfall and strong rainfall would cause a large number of pollutants loss.