茅坪河流域非点源污染负荷模拟

为定量化研究茅坪河流域农业非点源营养物质氮、磷的输出负荷,在茅坪河的亚流域陈家冲,利用2004-05～2004-10降雨期的监测数据,通过实测值和模拟值的比较对非点源污染模型SWAT(Soil and Water Assessment Tool)进行了率定和验证,采用Nash-Sutcliffe系数(R²)、均方根差(RMSE)和相对误差(CV)检验实测值和模拟值的拟合度.利用验证后的模型模拟了茅坪河流域营养物质氮、磷的输出负荷量.经验证径流、总氮和总磷的Nash-Sutcliffe系数分别为0.71、0.51和0.62,最小相对误差分别为1.8%、1.1%和10%,模型对氮和磷的输出模拟效果稍差,但对径流的模拟取得了较好的效果,表明该模型可运用于茅坪河流域非点源污染的模拟研究.模拟结果显示,2004-05～2004-10,茅坪河流域共有102.5 t氮和9.46 t磷流入长江,大量农业非点源污染的产生是造成茅坪河水质恶化的重要原因之一.

Simulation of Nonpoint Source Pollution Load in Maoping River Watershed

The nitrogen and phosphorous transport in the Maoping River watershed was modelled using the SWAT model,which simulates the water cycle and the transformation of nutrients.The model was first calibrated by comparing the observed and the simulated data from May to October 2004,and then validated.The Nash-Sutcliffe coefficient(R²),the mean square root error(RMSE) and the relative error(CV) were used to test the agreement between observed and simulated data.The validated model was then be used to simulate the nutrients load in Maoping River watershed.The Nash-Sutcliffe coefficient of flow,nitrogen and phosphorous was 0.71,0.51 and 0.62 with the minimum relative error 1.8%,1.1% and 10% respectively.Despite achieving the relatively lower resemblance between observed and simulated phosphorous and nitrogen load the model showed good agreement in simulating runoff.The results showed that 102.5t nitrogen and 9.46t phosphorous entered intoYangtze River during May to October 2004.One of the important reason that caused the water quality deterioration can be attributed to the nonpoint source pollution.