中文摘要：

以大宁河流域为研究区域，应用SWAT模型进行了流域农业非点源污染负荷的模拟计算。利用巫溪水文站2000～2004年的实测日径流和泥沙数据进行模型的调参计算，验证结果表明模型适用于大宁河流域。利用验证后的模型分析了不同降雨一径流条件下非点源污染的产输出特性。结果表明：降雨量对径流污染负荷有较大的影响，年内丰水段，非点源污染物浓度峰值和径流峰值同步出现；年内平水段，泥沙浓度、有机氮浓度和径流峰值同步出现，硝酸盐浓度峰值滞后于径流峰值出现时间；年内枯水段，非点源污染物浓度滞后于径流峰值度出现时间；降雨一径流与污染物浓度之间存在着密切的线性相关关系。

英文摘要：

SWAT model was used to evaluate agricultural non-point source pollution of Darting River watershed. Monitoring data of runoff and sediment from 2000 to 2004 were used to calibrate the parameter and validate the model, and results indicated that SWAT model was appropriate for the River watershed. The calibrated model was used to evaluate the loading of non-point source pollution, and results showed that the concentration of agricultural non-point source pollution was affected seriously by the intensity of rainfall. The peak value appeared in the same time in wet period, while the concentration of agricultural non-point source pollution lagged the runoff in dry period. Agricultural non-point source pollution and runoff had close linearity correlation in the River watershed.