基于SWAT模型的图们江流域氮磷营养物非点源污染研究

Non-point Source Pollution of Nitrogen and Phosphorus Nutrients Using SWAT Model in Tumen River Watershed,China

运用数学模型模拟非点源污染物的空间分布及其输移转化机制,是当前农业非点源污染研究中的重要手段和途径之一。流域尺度长时段分布式水文模型SWAT(soil and water assessment tool)应用于我国南方许多流域的非点源污染模拟上都取得了较好的结果。利用SWAT模型建立了东北图们江流域非点源污染数据库,对该流域(中国一侧)划分为5个小流域46个水文单元,分别进行了水文模拟、降雨径流和土壤侵蚀量计算。结果表明,图们江流域农业非点源污染主要的发生区在流域中部,海兰河和布尔哈通河交界的区域内。该区内有机氮和有机磷的非点源污染负荷明显高于其他地区,推测认为该区域为延边州首府延吉市所在地,城市建设和经济发展带来了繁荣,也造成了局部地区的植被破坏、土地裸露,水保能力下降,因此水土流失现象比较严重。另外,通过分析流域内有机氮和有机磷的时空变化特征发现,2007年延吉、龙井地区为氮磷营养物非点源污染最大发生区(有机氮9.76t.a-1,有机磷1.24t.a-1),而2008年除延吉、龙井地区外,珲春地区有机氮和有机磷非点源污染均有加重的趋势(分别由1.39t.a-1上升到3.82t.a-1,0.17t.a-1上升到0.48t.a-1);氮磷营养物的空间分布特征表明,2007年与2008年除了延吉、龙井一带为最大发生区外,珲春地区有机氮流失有所加重(从1.39t.a-1上升到3.81t.a-1),有机磷流失也有所加重(0.17t.a-1上升到0.48t.a-1),而安图等地区则有所减轻。

The mathematical model is an important tool and method in the study of agricultural non-point source pollution.It is particularly useful for simulating spatial distribution,as well as the transport and transformation mechanism of non-point source pollutants.SWAT（soil and water assessment tool）,a watershed scale and long term distributed hydrologic model,has been applied in the simulation of non-point source pollution in many watersheds of southern China.In this paper,a database of non-point source pollution from Tumen River watershed in the northeast of China was established by using SWAT model.The Chinese side of this watershed was divided into 5 sub-basins and 46 HRUs（hydrologic response units）.The hydrologic simulation,runoff and soil erosion were calculated for these sub-basins and HRUs,respectively.The results showed that the agricultural non-point source pollution mainly happened in the joint area of Hailan River and Buerhatong River,and the middle area of Tumen River watershed.These areas had an evidently higher non-point source pollution load of organic nitrogen and organic phosphorus than other areas.The reason might be attributed to the highly contribution of non-point source pollution from the Yanji city,the capital of Yanbian state.The urban construction and economic development in the areas not only brought the prosperity,but also led to the vegetation deterioration and decline of conservation capacity to the water and soil,causing serious water and soil loss in these areas.At the same time,the analysis of spatial and temporal variation of organic nitrogen and organic phosphorus in the studied area showed that：in 2007,the most serious non-point source pollution of nitrogen and phosphorus happened in the areas of Yanji city and Longjing city（with organic nitrogen 9.76 t·a-1 and organic phosphorus 1.24 t·a-1）,and in 2008,the non-point source pollution of organic nitrogen and organic phosphorus had a increasing trend over time in Hunchun area（from 1.39 t·a-1 to 3.82 t·a-1,and 0.17 t·a-1 to 0.48 t·a-1 for organic nitrogen and organic phosphorus,respectively）,except the areas of Yanji city and Longjing city.The spatial distribution of nitrogen and phosphorus showed that：from 2007 to 2008,the loss of organic nitrogen and organic phosphorus appeared in the areas of Yanji city and Longjing city.The loss in Hunchun city area increased over time as well.However,the loss declined over time in the area of Antu city.