An Estimation Of Soil Loss Based On RS And GIS In China

Based on the general soil erosion equation RUSLE model,this study comprehensively uses RS,GIS,statistics,and other analytical techniques to calculate and extract the five types of natural factors that affect China's soil erosion,and explores large-scale erosion factors that meet the actual application.The calculation method was used to obtain a grid database of various indicators.The dynamic spatio-temporal change characteristics of each factor were evaluated quantitatively,and the distribution map of soil erosion factors in China was plotted.Based on this,RS and GIS techniques were used to complete the quantification of soil erosion in China.Evaluate and plot annual soil erosion modulus maps,annual average soil erosion modulus distribution maps,and soil erosion intensity classification maps from 2000 to 2015,and conduct spatio-temporal dynamic analysis of soil erosion based on quantitative evaluation results in order to provide a certain degree of control over soil erosion.The main conclusions of this study are as follows:(1)Based on the index definition of the RUSLE model,combined with the existing data,a factor calculation method for the appropriate study area was selected for the five factors of rainfall factor,soil factor,topography factor,cover management factor and water and soil conservation factor.Based on the TRMM rainfall data,a simple algorithm was used to calculate the annual rainfall erosion factor data set from 2000 to 2015,and the temporal and spatial distribution characteristics of rainfall and erosivity in China were analyzed.The analysis shows that the spatial distribution of annual rainfall erosivity in China is significantly correlated with the annual average rainfall,showing a decrease from southeast to northwest.The average annual soil erosion in the southern coastal areas is relatively high,and the peak value of soil erosion modulus occurs near Lhasa,Tibet,reaching 11001.2 MJ·mm·ha-1·h-1 Annual average rainfall erosivity is not very volatile,and it only appears high in rainy year.Using a 1:100 million soil database in China,the surface soil silt,clay,gravel,and organic carbon fields were extracted to obtain a distribution map of the physical and chemical properties of the soil.Using the EPIC model,the distribution of resistivity K values was finally calculated using ArcGIS software..Based on the STRM-DEM data and a large number of previous studies,a suitable slope gradient factor calculation method was selected to extract the topographic distribution map of the study area.Using the NDVI dataset of remote sensing data,the annual distribution of the C value of the cover management factor was calculated using the formula based on the ArcGIS platform.It was found that the distribution of the C value was significantly different in space,showing a trend of high northwest and low southeast.The high values are concentrated in the northwest,most of northern China,and the Qinghai-Tibet Plateau,while the average value is low in most parts of the south.The year-by-year coverage of managerial factors has shown a slight decrease,with individual years such as 2009 and 2014 slightly increasing,with average C values in the range of around 0.45.According to a large number of scholars' research,the distribution of water and soil conservation factors in the study area was calculated using the method of valuation.(2)During 2000 and 2015,the spatial distribution and change trends of soil erosion in China are roughly the same.The differences in spatial distribution between east and west regions are obvious.Most of the country is dominated by micro-erosion,and mild erosion mainly occurs in the Tianshan Mountains and the southwest of the Tibetan Plateau.In the Ministry,the Kunlun Mountains,the Loess Plateau,the Greater Khingan Range,and most of the south,moderate to moderate erosion is concentrated in the Qilian Mountains and much of southeastern Qinghai-Tibet Plateau.(3)From 2000 to 2015,the national soil erosion modulus showed a downward trend as a whole,and the maximum and average values in individual years were fluctuated by the influence of precipitation and climate in the same year.This shows that the construction of soil and water conservation in China is effective in preventing and controlling soil erosion.The dynamic changes of different types of erosion intensity in the two periods of 2000 and 2015 were analyzed,and the area with stable and constant erosion intensity was obtained.The area where the intensity was transferred accounted for about 7.98%of the total area of the study area.Grades tend to fall downwards,and soil erosion in a very small part of the area deteriorates and should be taken seriously.(4)Permanent glaciers,bare rocks and other types of unused land,shrubs and grasslands,especially high-covered grasslands,have a relatively serious degree of soil erosion,and land cover,forested land,lakes,rural settlements and other types of land cover Land-use types have less soil erosion and require targeted soil erosion control measures for different land-use types.The amount of soil erosion is greatly affected by the slope.As the slope rises,the average amount of soil erosion increases rapidly.The average soil erosion in the 0-80 range is 249.46 t·km-2·y-1,and when the slope is in the range of 8-15°,the average soil erosion modulus suddenly rises to 1043.60t·km-2·y-1..The higher the slope,the greater the average soil erosion modulus.When the slope is greater than 35°,the average soil erosion amount is 2371.05 t·km-2·y-1.Soil erosion in the national nature reserve is relatively serious,with an average soil erosion of 670.72 t·km-2·y-1,which is much higher than the national average soil erosion modulus of 354.66 t·km-2·y-1.Relevant departments pay attention.