Application Research On USLE Soil Erosion Model In Ta-pieh Mountains Area

This paper mainly discusses the applicability of the soil erosion model on the different watershed scales,and the differences and similarities of spatial and temporal distribution of soil erosion on different watershed scales,in order to find a new experience model suitable for this region's soil erosion conditions.The research area is located in the three river basins in yueyi county,south of Ta-pieh Mountains,anhui province,namely the Mao Jianshan river basin(84.63km²),the Sha Hebu river basin?252.13 km²?and the Qianshan river basin?955.82 km²?.It belongs to the source of the Yuexi water system,the Qianshui water system and the Da shahe river system,and the three basins are adjacent to each other,with regional climate change is the same type.This paper is based on Arcgis10.4 spatial analysis module and statistics module,used ENVI5.3's function of remote sensing image classification,based on remote sensing image,meteorological data,soil property data,DEM30m topographic map data,sediment monitoring data of soil erosion model factors such as database,through on-the-spot investigation visit,based on the revised universal soil loss equation?USLE?on the basis of introduction of gully erosion factor,the local regional soil loss equation in the studied area trying to build a new model of experience?USLE-G?,through to the three river basin's soil erosion modulus extraction and analysis,The simulation prediction results of two models will be evaluated and the applicable models of different data,analyze in 1989,2001 and 2015,the year of three different scales of soil erosion on slope,vegetation coverage change law of the land use heavy classified as three categories:forest land,cultivated land,the other,to explore different scale basins under the policy of returning farmland to forest,forest land conversion which is the main square of land use change,the change law of time and space distribution of soil erosion.The main research methods and conclusions are as follows:?1?the calculation of soil erosion model factor is mainly based on the common kriging space interpolation and ENVI classification in the field statistical analysis.The data of rainfall erosion force interpolation is the calculation result of the average monthly rainfall of 30 years from 1981 to 2010 of 16 sites in and around the study area.The soil erodibility factor is the data of interpolation point obtained by using the national secondary soil properties database,and by using the Arcgis10.4 randomly generated fishing nodes.The slope length factor is extracted from the DEM30m topographic map by means of the Arcgis10.4 surface analysis slope tool,and the slope length calculation is based on the slope length extraction method based on the one-way flow.Vegetation cover factor was used to extract vegetation cover based on binary dichotomy,and the C value was inverted by empirical formula.Factor P values for soil conservation measures,through consulting the related literature,to experience the assignment of land use types and land use classification is the ENVI supervised classification support vector machine?SVM?,visual interpreting correction in Arcgis.Gully erosion factor calculation model used in shallow gully erosion of the loess plateau is simple and easy calculation model,through the consult the analysis of the existing research results of the southern red soil hilly region of gully erosion,intends to employ more than 15°slope and vegetation coverage of less than 70%of the local gully erosion factors play a role.?2?the correlation between USLE and USLE-G model is above 0.99,which is highly correlated to the truth value.By calculating the average relative error of the simulation value with the observing,found Qianshan river basin>USLE simulation precision of Sha Hebu basin>Maojian mountain basin,USLE-G simulation accuracy for Sha Hebu basin>Qianshan river basin>Mao Jianshan basin,USLE simulation precision,precision without USLE-G Sha Hebu basin terrain is relatively flat,cultivated land area is large,USLE-G retained the USLE original evaluation characteristics on the basis of gentle erosion prediction of cultivated land area has a higher sensitivity.Mao Jianshan river basin,Sha Hebu basin and Qianshan basin by computing the two models,the efficiency coefficient of buried hill valley Ens,USLE efficiency coefficient is 0.8436?0.9317?09976,and the model of USLE-G efficiency coefficient is 0.9712?0.9938?0.999,and the introduction of gully erosion factor USLE-G model has a higher quality.?3?Mao Jianshan,Sha Hebu,Qianshan river basin each corresponding proportion quite slope belt area,is 15°²5°area biggest,8°¹5°area of times,the slope belt area of slope has a first increases then decreases.Before returning farmland to forest,Mao Jianshan basin contribution of the highest mountain and Sha Hebu watershed erosion is 25°³5°slope belt,the Qianshan river basin is the largest contribution to the erosion of the 8°¹5°slope belt;Biggest contribution after returning farmland to forest,three basin erosion area down to 8°¹5°slope belt,greater than 25°slope returning farmland to forest,erosion shift to the gentle slope belt.Before returning farmland to forest,Mao Jianshan basin and river small watershed of Sha Hebu during 0¹5°slope Sha Hebu belt to the degree of erosion and mild erosion area proportion is the largest,more than 15°above slope belt of the strong erosion and covers an area of the largest;Qianshan basins of different slope belt are micro erosion area of the largest,in 15°severe erosion area increased significantly.With the increase of cultivated land area,the forest division was overmined,and the erosion intensity of each slope was increased,which showed that the conversion of farmland to forest to improve forest quality could help curb soil erosion.?4?based on the area tabulation function of Arcgis10.4,the soil erosion characteristics of different vegetation types in different basins were extracted and analyzed,and the soil erosion intensity in the high coverage area was slightly eroded.Soil erosion modulus increased with the decrease of vegetation cover grade,and the soil erosion modulus increased from high coverage to middle and high coverage area.Period from 2001 to 2001,the quality of forest land,vegetation quality increases,the overall regional vegetation quality improvement,therefore in 2015 from2001,all levels of the areas covered by vegetation soil erosion intensity is far less than in 2001.?5?the change of land use,the main impact of basin is the change of vegetation cover,so the influence of land use change on soil erosion,vegetation factor must to be considered at the same time,the basin soil erosion modulus on watershed average vegetation coverage change has high sensitivity,both present good negative correlation.With the implementation of returning farmland to forest,the improvement of land use change in the way,the vegetation quality,various land use types above the intensity of erosion and the erosion area is small,erosion intensity center shift to micro,mild erosion degree of erosion;Various land use type under extremely strong erosion and its erosion intensity area,the average erosion modulus basically remain unchanged,a slight drop in severe erosion modulus of the cultivated land,forest land and other land use intense erosion modulus decline;Decline of land use types of erosion,land erosion,the biggest contribution of the severe erosion,such as land and other land erosion of soil source from intense erosion moving in the direction of micro degrees of erosion area.