三峡库区小江流域溶解态氮素污染模拟

Simulation of dissolved nitrogen pollution in Xiaojiang river basin of Three Gorges reservoir

小江是三峡库区中部北岸流域面积最大的一级支流,农田以紫色土坡地为主,随降雨形成的地表径流和壤中流流失的非点源溶解态氮是水体中氮素污染的主要来源。根据小江流域地形、土壤等特性,构建流域溶解态氮素污染模型,并将具有物理机制的SLURP分布式水文模型引入污染模型中地表径流和壤中流的模拟,借助GIS技术,对小江流域2000～2007年溶解态氮的输出量与负荷的时空分布进行了模拟与定量计算。结果表明:土地产生的负荷占总负荷的68.3%～76.8%,农村居民点产生的负荷占23.2%～31.7%;土地产生的负荷中85%以上来源于农田。

Xiao-Jiang River is the largest tributary on the north of the middle part in Three Gorges reservoir area, because of predominant billy cropland with purple soil, the dissolved nitrogen from surface and subsurface runoff caused by raining accounts for most part of the nitrogen pollution in water. This paper develops the annual pollution models based on the characteristics of topography and soil, etc. , of the basin in order to study dissolved nitrogen pollution, and introduces a Semi-distributed Land Use-based Runoff Processes （SLURP） hydrological model into the surface and subsurface runoff simulation which is an important part of non-point source pollution modeling. Integrated with the geography information system technology, the annual temporal-spatial distribution of the dissolved nitrogen in the basin is simulated and the load at the watershed outlet is estimated from 2000 to 2007. The results show that the load from cropland is up to 68.3%-76.8% of the total load, in which over 85% from croplands and then rural settlement is 23. 2-31.7%.