Assessment Of Soil Erosion In Pakistan Based On GIS Technology And CSLE Model

Soil erosion has become one of the most serious problems that damage the soil,threatening the regional ecological environment and sustainable development seriously.Pakistan is one of the countries with the most serious soil erosion in the world,however,there is no research about soil erosion evaluation in Pakistan,lacking of evidence for the treatment of high soil erosion areas.Therefore,carrying out soil erosion research in Pakistan has important practical significance for soil erosion control and construction of land ecological security pattern.This paper takes Pakistan as the research object,based on the Chinese Soil Loss Equation(CSLE),taking soil erosion sampling survey units and soil erosion factor datasets such as rainfall erosivity factor(R factor),soil erodibility factor(K factor),slope steepness and slope length factor(LS factor),biological measure factor(B factor),engineering-control practices factor(E factor)and tillage practices factor(T factor)as data sources,spatial interpolation and map algebra method were used to make soil erosion maps for water erosion area.Then use the spatial interpolation result as a reference to update the map algebra calculation result with histogram matching to obtain the Pakistan water erosion rate map,which is to explore the correction and optimization of the results of the two methods.Analyze the spatial pattern and main controlling factors of soil erosion in water erosion areas.According to SL190-2007 standard,qualitatively evaluate the erosion intensity and distribution of wind erosion area.Finally,the characteristics of soil erosion in Pakistan are analyzed.The main research contents and conclusions of this paper are as follows:(1)Large spatial differences in rainfall,low and large spatial difference of vegetation coverage and large topography are the most important characteristics of soil erosion factors in Pakistan.Among the factors affecting soil erosion in Pakistan’s water-eroded areas,the high values of rainfall erosivity,slope and length factors are concentrated in the northern mountainous areas,which are important factors for soil erosion;biological measures are the main factors to alleviate soil erosion,but the vegetation coverage in the water-eroded area is overall at a low level,which is also an important factor for serious water erosion and wind erosion.(2)Based on the statistical distribution characteristics of soil erosion map by spatial interpolation method,the histogram matching of soil erosion map based on map algebra can better complete the mapping of soil erosion rate.This study is based on the CSLE model,using map algebra method and spatial interpolation method to calculate the soil erosion rate in Pakistan’s water erosion area.Taking the spatial interpolation soil erosion image element value as a reference,obtain the result of map algebraic correction and optimization through histogram matching,which has the advantages of the accurate prediction of the spatial interpolation map and the local variation characteristics of the map algebra map.(3)The overall soil erosion in Pakistan is serious and the regional difference is large.The soil erosion of the water erosion area presents a spatial pattern of high soil erosion in the northern mountainous area,the Potohar Highlands and the Baluchistan desert along the southwest,and low soil erosion in the farming area of the Indus Plain.The average soil erosion rate in the water erosion area is 953.6 t/(km2·a),65.7% of the water erosion area is above200 t/(km2·a),and 45.2% of the area is above 500 t/(km2·a).30.1% of the area is above 1000 t/(km2·a),and 9.2% of the area is above 2500 t/(km2·a).Water erosion is relatively strong in general.The wind erosion area is dominated by severe and extremely strong wind erosion,because the vegetation coverage is generally low.(4)Vegetation coverage factors are the most important factors affecting soil erosion in water-eroded areas,followed by terrain factors and rainfall factors.The importance of soil erosion factors in the water erosion area is ranked B>LS>R>K>T>E.Soil erosion of different land use types corresponds to different main controlling factors.The main controlling factors of forest and grass areas,cultivated areas and mountainous areas are biological measure factor B,rainfall erosivity factor R,slope steepness and slope length factor LS.