| The quick evaluation of soil erosion intensity is of great significance for the efficient formulation of regional soil erosion prevention and treatment programs.The traditional soil erosion evaluation research requires repetitive operation on professional software through image preprocessing to the calculation of factors and amounts of soil erosion of the research area,which is time-consuming labor-intensive,costly and the time liness of treatment was affected.With the rapid development and maturity of“3S”(RS,GIS,GPS)technology,soil erosion evaluation research has also ushered in a new opportunity.This paper chooses Chongqing Qijiang District as the research area,based on the general soil loss equation(RUSLE)combined and revised with RS and GIS technology and does some study on the following aspects:(1)Remote sensing images extracted vegetation coverage with high precision under the influence of terrain in the research area.In this paper,the Landsat8 OLI remote sensing image with resolution of 30m is used.Because the research area is a complex mountainous terrain,in order to improve the accuracy of vegetation coverage under the influence of relief amplitude,the ENVI5.3 was used for geometric correction of remote sensing image is carried out using ENVI5.3.At the same time,the FCD model was choosed to calculate the vegetation coverage factor C,which weakened the influence of complex terrain and relief amplitude on the accuracy of vegetation coverage factor to some extent.(2)Model Builder spatial modeling extracts soil erosion sensitivity factors and calculates soil erosion amount.Based on the basic data of the research area:remote sensing image,annual rainfall data,topographic map,soil type data and land use data,this paper selects the most commonly used revised general soil loss equation(RUSLE)as basis.Using the Model Builder of ArcGIS10.2 to extract the six major soil erosion sensitivity factors and calculate soil erosion amount model.The soil erosion intensity estimation is completed efficiently on the basis of basic data preprocessing,which greatly reduces the repetitive operation on this time-consuming and laborious soil erosion sensitivity factors extracting and soil erosion amount solving.(3)Analysis of soil erosion characteristics under different sensitivity factors.Based on the classification and gradation results of soil erosion intensity after evaluation,the soil erosion characteristics of different vegetation coverage,different soil types,different elevation zones,different slope gradient and different land use types in Qianjiang District in 2015 were further analyzed.Based on the rapid estimation of soil erosion intensity in the Qijiang District,the following conclusions have been drawn:(1)The soil erosion phenomenon in Qijiang District is relatively common.The area of soil erosion that has occurred is 2665.1312km~2,accounting for 97.02%of the total land area of the Qijiang District;the unaffected soil erosion area is 81.8686 km~2,accounting for 2.98%of the total land area of the Qijiang District.The total amount of soil erosion in the Qijiang District in 2015 was 6365458.975t.(2)There are six types of soil erosion in Qijiang District:slight erosion,mild erosion,moderate erosion,serious erosion,extreme erosion and severe erosion.The main types of soil erosion are slight erosion and severe erosion.Both lead the total erosion area is 2404.239 km~2,accounting for 90.3%of the total land area in the Qijiang area.The total erosion generated by the two is 5360337t,accounting for 84.19%of the total erosion.(3)The soil erosion status of different soil erosion sensitive factors is obvious,and the slope gradient and land use type are of the most greatest impact.Through the soil erosion characteristics under the influence of various soil erosion sensitivity factors analysis,it is obvious that the single impact factor can not determine the magnitude of soil erosion intensity,but the combination of natural environmental factors and human factors are decisive. |
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