The Study On The Soil Erosion And Its Influencing Factors In Chenggou River Watershed Based On GIS And RS

The experiment was carried outin River Watershed Watershed on the Loess Plateau in central Gansu.Based on the data of DEM,remote sensing images and rainfall runoff sediment observation,the RUSLE model in GIS and RS was used to simulate the soil erosion in River Watershed Watershed.Based on the data of rainfall and terrain,the effects of rainfall and topography on soil erosion were analyzed.Based on the siltation units of silt storage dam for farmland building,the relationship between soil erosion and land use was qualitatively and quantitatively analyzed.It can be used as a reference for the study of soil erosion in the small watershed and the same type.The main conclusions of this study were as follows:(1)The results indicated that the soil erosion was mainly micro and mild erosion in River Watershed Watershed.The average soil erosion modulus was 618.31 t/(km2·a),and the average annual soil loss amount was about 9.93 thousand t/a.Most of the area of soil erosion had been effectively controlled,but some areas were still serious.Some sheet erosion of adrets were still serious,there were some phenomena of gravity erosion such as landslide and collapse.(2)In recent 10 years,the mean annual precipitation of River Watershed Watershed was 399.23 mm,the average annual rainfall of flood season was 280.85 mm,and the average annual erosiveness rainfall was 172.30 mm,accounting for 43.16 % of the average annual rainfall.The interannual variation of erosional rainfall in the Watershed had a significant effect on the soil erosion,while the annual rainfall and annual rainfall had a relatively small effect on soil erosion.The main rainfall indexes affecting the size of soil erosion during the year were the number of rainstorm and soil erosion was mainly caused by one or several rainstorms.(3)The relationship between topographic factors and soil erosion was very significant in River Watershed Watershed.In elevation,the soil erosion and the elevation were negatively correlated with the elevation.With the increase of elevation,the soil erosion modulus decreased significantly and the soil erosion degree decreased.On the slope,the soil erosion and the slope were positively correlated with the slope.With the increase of slope,the soil erosion modulus increased significantly and the degree of soil erosion was enhanced.On the slope direction,the soil erosion modulus decreased from sunny slope,semi-sunny slope,semi-shady slope to shady slope,and the degree of soil erosion was weakened.(4)The land use of the River Watershed Watershed was mainly terraced,grassland and woodland,accounting for 86.08 % of the total area of the Watershed.In terms of soil erosion modulus of different land use types,terraced fields < artificial grassland < shrub land < forest land < dry land < natural grassland < construction land < slope farmland < bare land.Among them,the terraced fields and artificial grassland were the main reduce sand types,and natural grassland and bare land were the main sand production types.