Research on Management of Non-point Source Pollution with Land Use Changing in Three Gorges Reservoir,Macro-scale Watershed Based on SWAT

This paper applied SWAT(Soil and Water Assessment Tool) model into the macro-scale watershed,with Three Gorges Reservoir(TGR) area as a case study.Effect of land use changes on non-point sources(NPS) pollution in TGR watershed was quantitatively analyzed on six scenarios designed with the baseline in 2005.Firstly,the SWAT model was calibrated and validated using the monitoring data during 2002—2008,with values of R2 and ENS(Nash-Suttclife efficiency) are satisfying,indicating this model performing well in simulating the runoff and yields of sediment and nutrients.After that,the calibrated SWAT model was used to simulate on six different land use scenarios and examine the effects of land use changes on the NPS pollution control in the watershed.The results showed that the slope farmland contribute dominantly to the NPS pollution in terms of yields of sediment,TN and TP.If the farmland,especially above the slope of 25,is changed into woodland,a better control and reduction of the NPS pollution could be achieved.On the contrary,the reverse process would aggravate NPS pollution seriously.This study provides a good understanding of the interactions between land use and NPS pollution,which is helpful for making sound decisions.It could help reducing the NPS pollution effectively and thus play a significant role in improving water quality of the TGR watershed to change the land use pattern and implement alternative management practices.