AN EXPERIMENTAL STUDY OF SHEET EROSION IN GRANITIC REGION OF WUHUA COUNTY,GUANGDONG PROVINCE

1.IntroductionWuhuaCounty,locatedintheupstreamOfHanjianghiver,isoneofthemostseriouslyerodedcountiesinSouthChinagraniticweatheringregionOfGUangdOngPrOvince.ByinveStighion,thetOtalerodedareaisestimatedtobe875.33km,whichoccupiedbot30percentofthetOtalerodedareaoftenmostseriouserodedcountiesintheregion.Insomeconununes,theeroddareaevenreachedtomorethan6Opercent.ErosionresuItedinwidesPedOfbemountalns,landdopadaion,shortOfwterresourceshoperecotw.~ngthethreetypesoferosionintheupstreamOfHanjian…

AN EXPERIMENTAL STUDY OF SHEET EROSION IN GRANITIC REGION OF WUHUA COUNTY,GUANGDONG PROVINCE

The relationships between rainfall, runoff and erosion in South China granitic weathering red soil region were studied by using data collected from 7 experimental plots in Wuhua County, Guangdong Province. Results showed that when rainfall is less than 50 mm, small volumes of runoff were produced. Rainfall intensity might be the main factor in controlling runoff. When rainfall exceeds 50 mm, because of its large volume and high intensity, runoff and the produced amount of erosion increased with raimfall quickly. Analysis of the relationship bebeen runoff and erosion suggsted that runoff of 30 mm (corresponding to about 50 mm rainfall might be taken as a threshold at which wter on land surface was sufficient to start the larg amount of soil particles. Vegtation cover is very effective in protection soil from being eroded. When vegetation coverag increases from 0 to 80 percent,runoff and soil loss decrease from 179.34mm/a to 126.36mm/a and 6262.15T/a km2 to 368.02 T/a km2, respectively.