Study On The Method Of Risk Evaluation Based On Water Erosion Consequence

Research on risk evaluation of soil erosion can help us scientifically predict the occurrence of soil erosionand give a reasonable evaluation of its harm. Then we can take effective measures to achieve theimplementation of protection and sustainable utilization of soil resources.Soil erosion degree and its potential risk for the scientific investigation area in the red soil region ofSouthern China,as well as sediment delivery ratio for the main lakes within the basins in the region,weregradated based on the MWR (Ministry of Water Resources) Standards for Soil Erosion ClassificationGradation,the data from the scientific investigation by the MWR from2005to2005and the date from Soil andWater Conservation Center from2001to2002, combination of historical data and case,empirical research andtheoretical analysis,qualitative analysis and quantitative analysis, meanwhile,through analysis of the recoverytime of herbaceous vegetation and antierosion period in main water erosion areas,educed the danger of soilerosion on the recovery of the ecological system,sorted the risk of soil erosion according to the importance theyplayed in national development.Results showed that there were light,moderate,intense and extremely intense soil erosion degrees in theinvestigated area. The moderate erosion and intense erosion were the main soil erosion types and accounted for84%of the whole area,while the light erosion and extremely intense erosion accounted for16%. The types ofno risk,light risk,risk and extreme risk were all found in the potential risk gradation. The light risk and riskwere the main risk types and accounted for84%of all the risk types,while the no risk and extreme riskaccounted for16%. Soil erosion was harmful to the places nearby.Sediment delivery ratios in60%of the lakes were greater than0.5,which indicates that soil erosionoccurred in the upstream of the lakes is dangerous,even extremely dangerous to the places nearby.Revegetation capability of the main water erosion areas was:desertification region in the southwest＞redsoil and hilly region in the south＞loess hilly and gully region in northwest＞rolling hill region in northeast＞soil and rock region in north.Longth of antierosion period of the main water erosion areas was:loess hilly andgully region in northwest＞red soil and hilly region in the south＞rolling hill region in northeast＞desertification region in the southwest＞soil and rock region in north.Integrated revegetation capability,antierosion period and importance of regional character,risk of soilerosion on the main regions was:loess hilly and gully region in northwest＞rolling hill region in northeast＞ desertification region in the southwest＞soil and rock region in north＞red soil and hilly region in the south.For the regions of short antierosion period,lack of revegetation capability and being relativelydry,northwest region for example,we should take preventive measures,especially the existing vegetationprotection measures. For the regions of long antierosion period,being humid and suitable for the growth ofvegetation,southwest region for example,we should take measures of soil and water conservation,especiallymeasures of basic vegetation recommended.This paper based on the consequence of soil water erosion,combined influence of the soil erosion on localregion,region nearby and the ecological restoration,provides a relatively comprehensive and systematicalmethod of soil water erosion risk evaluation,hope to be a reference to the theoretical research and practice inthe future.