The Research On Non-point Source Pollution In Changsha City

With the control of industrial pollution and domestic pollution, non-point source pollution is becoming the main reason for water pollution. because non-point source pollution is random,widespread,lag behind,fuzzy, the prediction and control on non-point source pollution is greater difficulty. Through establishing the prediction model of non-point source pollution and using this model in Changsha City to calculate non-point source pollution of nitrogen and phosphorus. In order to understand further about the impaction of non-point source on water quality, assess water quality of Liuyang River by the improving integrated pollution index. Extract the non-point source pollution map of Liuyang River from the non-point source pollution map of Changsha City which build by the model.combing with the surface water basin environmental characteristics to know impacts of non-point source pollution on water quality . Research conclusions are as follows:(1) Research conclusions of non-point source pollution in Changsha City the non-point source pollution of nitrogen and phosphorus in Changsha city are 9.9 kg/(hm2·a) and 1.49 kg/(hm2·a) respectively.The non-point source pollution of nitrogen is mainly in the form of dissolved nitrogen , is closely related to surface runoff ; the most polluting source is from the urban land which has lager impervious surface coverage of underlying surface and generates lager surface runoff during rainfall process. The non-point source pollution of phosphorus is mainly in the form of adsorbed nitrogen, the most polluting source is from the land which has larger slope and easily generates the water and soil erosion.(2) Research conclusions of surface water quality of Liuyang River From the temporal characteristic, because of non-point pollution the water quality of Liuyang River watershed was becoming serious nearly ten years. From the spatial characteristic, the pollution assumed increasing from the upstream to the downriver, water quality in upstream was better, the content of the heavy metal was bigger in the middle of the river ,the pollution of ammonia nitrogen intensified in downriver。...