MODELLING SOIL EROSION AND SEDIMENT YIELD IN A SMALL WATERSHED OF THREE GORGES RESERVOIR AREA BASED ON SCS-CN AND MUSLE MODEL
Soil erosion affected by a variety of natural factors and human activities has been a major concern to the public for decades.It is difficult for modelling soil loss using former soil erosion model to determine sediment transport coefficient,while soil erosion distributed models need a large number of input data.Among soil erosion models,the universal soil loss equation (USLE) is the most widely used and misused soil loss estimation equation in the world.The USLE was originally applied to the prediction of soil losses from agriculture in the USA,in order to preserve soil resources,but has been extended for use in numerous countries.USLE is an empirical equation that predicts annual average,long-term soil erosion,but does not simulate dynamic and continuous changes.The MUSLE model estimates sediment yield on a single storm basis and the output is interpreted as sediment yield coming at the outlet of the catchment.This is computed based on a combination of runoff and catchment characteristics.In addition,the integration of GIS has evolved from the advances in geospatial techniques and the increasing availability of spatial databases.The SCS-CN model and the MUSLE model were used to model soil yield for every rainfall.A small watershed,Songjiagou watershed in Three Gorges Area (TGA),was chosen to validate the SCS-CN and the MUSLE model applicability based on rainfall,vegetation coverage,soil,and DEM data.The accuracy of the simulation values of the model is in an acceptable range.Soil loss in the watershed in 2013 was 3 923 t,80％ of which was from the 5 largest rainfall events.Sediment yield from different land uses varies considerably.81.54％ of sediment loss was from cultivated land,which accounted for 44.63％.However,forestland with an area of 47.61％ of the whole watershed,only contributed to 17.63％ of the sediment loss.Grade differences in slope had a great influence on sediment yield.Only 1.75％ of sediment was from area with slope in the 0-8 degrees,while the area with slope more than 25 degrees contributing to 55.77％ sediment.The reason of larger sediment simulation value compared with the measured values may be pond interception effect.The role of pond in changing hydrologic effect and migration of sediment need follow-up study.
Three Gorges Reservoirerosion and sedimentMUSLE modelSCS-CN model
NETL
NSTL
万方数据
维普
