Monitoring And Analysis Of Soil Erosion Responsed To Annual Vegetation Variation

Annual vegetation variation will affect the accuracy of soil erosion(soil loss)estimation.Remote sensing images,combined with rainfall data,topographical data,soil data,field study data were used in the paper.Based on the Chinese Soil Loss Equation(CSLE),the effect of annual vegetation variation on soil erosion estimation was studied.Taking Anxi County as an example,the effect of annual vegetation variation on soil erosion estimation was analyzed quantitatively,and the soil erosion of Anxi County in 2015 was calculated and analyzed.The main research contents and results are summarized as follows:(1)Selection of remote sensing data in suitable season for B factor calculation.Based on CSLE model,relative deviation was used to analyze the effect of difference of seasonal aspect on soil erosion estimation in remote sensing images.Then the suitable season of remote sensing data was chosen.The results show that:In the case of more rainfall,normal rainfall or less rainfall,the difference between soil erosion estimation based on images in February and August and reference value were found obvious.The spatial distribution of relative deviation in February was mainly overrated while underrated in August.Soil erosion estimation based on the images in June and that in October was most close to reference value,with more suitable season.Remote sensing data in October were easier to obtain,which were chosen for estimating B factor.(2)Soil erosion monitoring and analysis of Anxi County based on CSLE.The suitable methods for model factors extraction and calculation were adopted,and the soil erosion of Anxi County in 2015 was estimated and verified based on CSLE.The results show that:The area of soil erosion in Anxi County in 2015 is 638.09 km2,with soil erosion rate at 21.31%.The soil erosion intensity concentrated more in light while less in serious and above serious.The soil erosion concentrated more in north central part and southern part of Anxi County.The soil erosion was found most serious in Shuangxi river basin and Dashe river basin.Meanwhile,the soil erosion was found serious in a range of slope degree between 15 and 25 and altitude between 200 meters and 500 meters,which need to be controlled in the future.(3)Quantitative analysis of the effect of annual vegetation variation on soil erosion estimation.Based on flexible spatio-temporal data fusion model(FSDAF),monthly moderate spatial resolution vegetation index time-series were constructed,for calculating B factor.The soil erosion modulus calculated on monthly accumulation method has been adopted as reference value,and the differences between the soil erosion modulus calculated on different B factors and the reference value were analyzed,for discussing the effect of annual vegetation variation on soil erosion estimation.The results show that:The ratio of soil erosion in each month on monthly accumulation method was highly related to monthly average R factor but not to vegetation cover.Affected by vegetaion growth,the soil eroion was found most serious when B factor was calculated in February while least in August.Soil erosion calculated on the images from May to June and from October to November were most close to that on monthly accumulation method.Therefore,we can control soil erosion by change the vegetation cover.