灞河流域产流产污的时空特征模拟研究

Simulation on Temporal and Spatial Characteristics of Runoff and Pollution in Bahe River Basin

[目的]探究灞河流域非点源污染物总氮(TN)和总磷(TP)时空演变特征及其与年径流量的负荷关系,提出污染负荷的空间分布规律,为流域规划治理提供思路。[方法]以1996年和2017年两期土地利用数据和2001-2017年灞河流域降雨数据为基准,基于GIS技术和AnnAGNPS模型开展现状模拟与情景设计。[结果]①相比1996年,2017年林地和耕地的面积减少,建设用地、水域等面积增多;模拟结果显示建设用地产流定额增加,TN负荷定额增加,TP负荷定额增加;林地产流减少,TN负荷减少,TP负荷减少;水域的产流、TN和TP负荷基本无变化。②2017年建设用地TN污染负荷相比1996年(5.24 kg/hm^(2))增加到16.13 kg/hm^(2),一定程度上反映了灞河流域近20 a城市非点源污染的严重性。③径流最大的区域是清峪河、灞河上游、清河以及辋川河这4个子流域。当径流值大于4.00×10^(8)t时,TN和TP污染物负荷处于高负荷状态。④辋川河、库峪、岱峪以及清峪这4个子流域的TP,TN负荷分布占到了灞河整个流域的50.32%,56.09%。[结论]目前非点源污染是灞河流域的主要污染源,尤其要重视城市非点源污染。

[Objective]The spatial and temporal evolution characteristics of total nitrogen(TN)and total phosphorus(TP)pollutants in the Bahe River basin and their load relationship with annual runoff were explored,and the spatial distribution law of pollution loads was proposed to provide guidance for watershed planning and control.[Methods]Based on the land use data for 1996 and 2017 and the rainfall data of the Bahe River basin from 2001 to 2017,the current-situation simulation and scenario design were carried out based on GIS technology and the AnnAGNPS model.[Results]①Comparing the land-use-type data in 2017 with 1996,the areas of forest land and cultivated land type decreased and the areas of construction land and water increased.The property flow quota for construction,the TN load quota,increased,and the TP load quota increased whereas that of the forest type(TN load)and the TP load decreased.For the production flow,the TN and TP loads in the water type were basically unchanged.②Based on land use data in 2017,the TN pollution load of construction land increased to 16.13 kg/ha compared with that(5.24 kg/ha)in 1996,which partly reflected the severity of urban non-point-source pollution in the Bahe River basin in the past 20 years.③The largest areas of runoff were the four sub-basin basins of Bahe River,including the Qingyu River,upper Bahe River,Qinghe River,and Wangchuan River.When the runoff value was greater than 4.00×10^(8)t,the TN and TP pollutant loads were in a high load state.④The TP and TN load distributions in the four sub-basins,including the Wangchuan,Kuyu,Daiyu,and Qingyu rivers accounted for 50.32%and 56.09%of the entire river basin,respectively.[Conclusion]At present,non-point-source pollution is the main source of pollution in Baba River basin,especially for urban non-point-source pollution.