Study Of Non Point Source Based On GIS

In recent years, with the developing of economic and the increasing of requirement to environmental quality in home, non point source pollution become more grave than before. Now, more and more environmental experts pay attention to it. Non point source drive from different area and its extension is wide. Now, it has been the main polluted source in watershed of Tai lake. Estimate its produce load is very difficult. In the article, based on the developed research of non point source at home and abroad, select three model: Taihu runoff model, SWAT model, and PLOAD model and apply them to Zhangjiagang area, then conclude the availability of this model .The details as follows:1) Select the sourthwestern region in Zhangjiagang county and apply Taihu runoff model to calculate runoff coefficient of every landuse type and runoff in from 1998 to 2002.2) According DEM partition the watershed into a number of subwatersheds or subbasins. Merging the Taihu model and referring the measure data in similar region, use the PLOAD model to statistic the annual pollutant load in Zhangjiagang watershed from 1998 to 2002. Compare the no point source and total pollutant in the region in 2002. The parameter PJ is deduced according to the runoff balance in the watershed.3) Introduce theory of the SWAT model. SWAT allows a number of different physical processes to be simulated in a watershed including climate; hydrologic response units or HRUs; ponds/wetlands; groundwater. Apply SWAT model to the watershed. The subbasin area is same to PLOAD model. And every subbasin is dominated by land uses or soils dissimilar enough in properties to impact hydrology. According to different land use select respective subbasins and simulate the surface runoff and non point source pollution. Use the calculating result by Taihu runoff model to calibrate runoff and ground water of SWAT model. Non point source pollution in rural and urban is calibrated by PLOAD result. Discuss SWAT model availability in plain watershed.4) Based on the foregoing study, select respective subbasin and use SWAT model calculate the decreasing non point pollutants by wetlands or ponds. Study the best management practices applied Zhangjiagang watershed.