| Soil erosion is a global environmental problem,which has been widely concerned by scholars at home and abroad,and it has become an important research means to study regional soil erosion by combining geographic information system and model.The soil erosion in hilly area of eastern China is mainly dominated by water erosion.This paper takes Dongping County,an important regulating lake of South-to-North Water transfer,as the research area.Based on the data of rainfall,soil and remote sensing images,the factors affecting soil erosion in Dongping County were analyzed by means of GIS and USLE model.In this paper,the spatial distribution and time variation of soil erosion of different intensities in the area are expounded,and the change of the gravity center of soil erosion in Dongping County from 1985 to 2015 is revealed,the results are as follows:(1)The rainfall erosivity affecting soil erosion in Dongping County decreased from northwest to southeast,and the average rainfall erosivity was 3780.12 MJ·mm/(hm2·h·a);Soil erosion factor decreased from south to north with an average value of 0.036;The high value of topographic factors is distributed in the low mountains and hills and the low value is distributed in the plain area;The high value of vegetation cover factor in tillage management is distributed in the low hills and impervious surface,and the low value exists in the water surface of lake and river;The low values of soil and water conservation measures were distributed on the impervious surface and the river and lake surface of the constructed area,and the high values were distributed in the low mountain and hilly areas.(2)During the past 30 years,the main sites of soil erosion in the county were mainly located in Dongping subdistrict office,Jieshan county,Jiuxian town and Laohu town,and more than 80% of the soil were in Slight intensity soil erosion.Slight intensity soil erosion mainly occurred under farmland land use type,strong soil erosion mainly occurred in calcareous coarse soil range,and other intensity soil erosion occurred mainly in calcareous initial soil area.With the increase of vegetation coverage,the decrease of rainfall,thedecrease of altitude and the decrease of slope,the value of soil erosion and the intensity of soil erosion will decrease.(3)In recent 30 years,the area of slight intensity soil erosion in Dongping County has been increasing continuously,which shows that the increase of soil erosion area is greater than that of transition.The strong,Extremely strong and violent of soil erosion decreased continuously,and the moderate erosion increased first and then decreased.The transformation rate of the moderate,strong and violent of soil erosion area was the largest in 30 years,followed by extremely strong and mild intensity soil erosion,and the most stable rate of soil erosion area with slight intensity.The transformation of low grade vegetation cover to high grade vegetation cover,the transformation of bare land and grassland land use types,and the decrease of total rainfall will lead to the decrease of soil erosion value and the continuous increase of soil erosion area with slight intensity.Thus,the center of gravity of soil erosion in Dongping County moves westward within the scope of Timen town. |
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