基于SWAT模型的渭河咸阳-西安段非点源污染削减措施研究

Reduction scenarios of non-point source pollution in Xianyang-Xi’an section of Weihe River Basin based on SWAT

【目的】针对渭河流域咸阳-西安段的非点源污染状况,模拟分析不同管理措施下非点源污染负荷的削减效果,为渭河流域的非点源污染控制与治理提供科学依据。【方法】构建渭河流域咸阳-西安段的非点源污染SWAT模型,利用2008-2016年逐月径流、水质及CMADS气象数据集等资料,对SWAT模型进行率定及验证,分析研究区内非点源污染特征;针对2016年研究区内非点源污染状况,设定4种管理措施,模拟验证不同管理措施在渭河流域咸阳-西安段对非点源污染负荷的削减效果。【结果】构建了渭河流域咸阳-西安段的非点源污染SWAT模型,该模型对研究区域具有较好的适用性和可靠性;2016年研究区域非点源总氮(TN)和总磷(TP)负荷的入河量分别为7654.0和626.5 t,主要集中在蓝田县、长安区、临潼区、鄠邑区、旬邑县以及彬县部分子流域;通过实施化肥减量、集中设置沼气池和加强水土保持等3项措施,可分别削减7.57%~29.11%、0.54%~32.85%和0.4%~23.12%的非点源TN负荷以及2.59%~15.99%、0.45%~28.65%和0%~39.79%的非点源TP负荷;将上述3种管理措施整合在一起的综合管理措施的削减效果较单一措施明显提高,其可削减9.98%~50.68%的非点源TN负荷和5.25%~52.84%的非点源TP负荷。【结论】渭河流域咸阳-西安段非点源污染的重点控制时段在汛期(6-10月),重点控制区域是蓝田县、长安区、临潼区、鄠邑区、旬邑县以及彬县部分子流域;加强水土保持和化肥减量是有效控制该研究区域非点源污染的重要措施。

【Objective】To help control non-point source pollution in Xianyang-Xi’an section of Weihe River,this study simulated the reduction effect of non-point source pollution loads by different scenarios.【Method】The SWAT(soil and water assessment tool)model of non-point source pollution for Xianyang-Xi’an section of Weihe River was constructed and verified by monthly observed runoff,water quality data and CMADS(China meteorological assimilation driving datasets)from 2008 to 2016.The SWAT model was used to analyze the characteristics of agricultural non-point source pollution.Four management scenarios of non-point source pollution were set and reduction effects were examined.【Result】The non-point source pollution model for Xianyang-Xi’an section of Weihe River was constructed and it had good applicability and reliability in the study area.TN loads and TP loads in 2016 were 7654.0 t and 626.5 t,respectively.Analysis of spatial-distribution regularity showed that sub-basins including Lantianxian,Changanqu,Lintongqu,Huyiqu,Xunyixian and Binxian were heavily polluted.The fertilization reduction,biogas digester construction as well as water and soil conservation scenarios reduced non-point source TN loads by 7.57%-29.11%,0.54%-32.85%and 0.4%-23.12%,and reduced TP loads by 2.59%-15.99%,0.45%-28.65%and 0%-39.79%,respectively.The reduction effect of combined scenario was better with 9.98%-50.68%reduction in TN loads and 5.25%-52.84%reduction in TP loads.【Conclusion】The key control period of non-point source pollution in Xianyang-Xi’an section of Weihe River was in flood season(June to October).The key control areas were sub-basins of Lantianxian,Changanqu,Lintongqu,Huyiqu,Xunyixian and Binxian.Both water and soil conservation and fertilization reduction were important measures to effectively control non-point source pollution in the study area.