Study On Non-point Source Pollution Of Nitrogen And Phosphorus Drainage Evaluating And It's Controlling On In ChaoHu Watershed

In recent years, with the developing of society economic and the increasing of requirement to environmental quality, non-point source pollution become more serious than before. Now, more and more environmental experts pay attention to it. Non-point source drive from different area and its extension is wide and uncertain factor is more. Now, it has been the main polluted source in ChaoHu lake watershed. Estimate its produce load is very difficult. In the article, based on the developed research of non-point source at home and abroad, utilizing GIS and selecting SCS model and USLE equation, evaluated produce load and overall outout of non-point source pollution of N and P in the ChaoHu lake watershed form two aspects of rainfall runoff and soil eroding combining export model of dissolved and particle N and P. On the basis of above related, study on controlling measures of non-point source pollution in ChaoHu lake watershed. The detalis as follows:(l)In the study area, datum of 1:25 ten thousand geography reference frame of country geographic information systems was dealed with (unifing projection and coordinate conversion) and analysed and showed by Arcview3.1 and Arc/info8.3 software. Administration zoning and Digital elevation model in ChaoHu lake watershed were accomplished, at the same time, correlative information like soil, vegetation, rainfall, society manage and so on was found. To make ready for next simulation.(2)Pollution loading of dissolved N and P in ChaoHu lake watershed could be evaluated through export model of N and P after annual runoff volume was work out according to SCS model. Parameter in SCS curve equation and export model need to be calibrated including intervening and being apparent annual rainfall of fourteen rainstation in watershed, evaluating and gridding runoff contamination thickness CDkt,and so on. Finally, many results were found for instance isoline chart of annual rainfall in ChaoHu lake watershed, space distributin chart of annual runoff volume, space distributin chart of dissolved N and P, etc.(3) Pollution loading of particle N and P in ChaoHu lake watershed could be evaluated through export model of N and P after annual soil eroding volume was work out according to USLE equation. Parameter in USLE equation and export model need to be calibrated including intervening and being apparent rainfall eroding factor R value in watershed, evaluating and gridding thickness of soil Nitrogen and Phosphorus, and so on. Finally, many results were found for instance distributing chart of soil runoff volume in ChaoHu lake watershed, space distributing chart of particle N and P, a series of important Parameter and variable factor chart, etc.(4)Based on evaluating of non-point source pollution loading, study ondecreasing non-point pollutants, bring forward the best controlling and managing practices of non-point source in ChaoHu lake watershed according to factual instance.