基于改进输出系数模型的流域营养盐输出估算

为合理估算流域非点源污染营养盐输出负荷，针对广泛使用的输出系数模型方法，通过实测数据推算获得流域主要土地利用类型氮磷营养盐输出系数，并同时考虑流域降雨的空间差异，对模型结构进行了改进，并与GIS实现融合，构建半分布式的输出系数模型.利用该模型对太湖上游的西苕溪流域氮磷营养盐输出负荷进行了估算，结果显示，西苕溪流域TN输出负荷为2 121.3 t，TP输出负荷为49.3　t，这为太湖流域非点源污染治理提供了参考，改进的输出系数模型具有很好的时空尺度适宜性和推广性.

Estimated Nutrient Export Loads Based on Improved Export Coefficient Model in Xitiaoxi Watershed

It is very important to estimate nutrient export loads from watershed, which is beneficial to water environmental management. The export coefficients for major landuse types were evaluated by field surveying data, in addition the spatial distributions of precipitation and runoff were considered, to improve on export coefficient model (ECM), then integrated ECM into geographical information system to compose half-distribution model of export coefficients. Estimated nutrients export loads based on the ECM in Xitiaoxi watershed located upper of Taihu Lake area. Results show that the export load for TN and TP was 2 121.3 t and 49.3 t respectively, which provides important reference value for nonpoint source pollution management.