Study On Quantitative Evaluation Of Soil Erosion In Hilly Area Of Central Sichuan Province

Soil erosion assessment is of great significance for regional soil erosion control policy.The traditional soil erosion research requires the professional to use the topographic map to draw the erosion map in the field by using the visual interpretation.It is difficult to monitor and evaluate soil erosion in large area.With the rapid development and maturity of 3S(RS?GIS?GPS)technology,the study of soil erosion evaluation has also ushered in a new opportunity.This study chooses the hilly area of central Sichuan basin as the study area.The data sources choose the 2010 annual rainfall,land use,soil,topography,remote sensing image data.Combined RS,GIS and other modern technology with traditional RUSLE model,RUSLE model based on SMA,BP artificial neural network model,the study quantitatively evaluate the soil erosion in hilly area of central Sichuan Province.By comparing the evaluation results of the three models,it is concluded that the RUSLE model based on SMA is the most reasonable.Finally,classified the soil erosion intensity,and further analyzed the Sichuan hilly area of different land use types,different vegetation coverage,soil type,soil erosion characteristics of different elevation.The main research conclusions are as follows:(1)Established the hilly area of soil erosion factors spatial database.With remote sensing data,observation data,thematic maps and written materials as the foundation,according to the requirements of the soil erosion quantitative evaluation,the study extracted the main factors that includes the soil corrosion factors(K),rainfall erosion force factor(R),vegetation management factor(C),slope length factor(LS)and the soil and water conservation measures factor(P)by ArcGIS and ENVI software.The study established the hilly area of soil erosion factors spatial database,and analyzed the various factors space variation characteristics.(2)The evaluation of soil erosion in the hilly areas of Sichuan Province in 2010 was carried out.The traditional RUSLE model,RUSLE model based on SMA,and BP artificial neural network model were used to quantitatively evaluate the soil erosion status.The characteristics of soil erosion intensity were studied.According to the results,the average soil erosion modulus values about the traditional RUSLE model,RUSLE model based on SMA,and BP artificial neural network model are 38.8 t/(hm2.a)?18.3 t/(hm2.a)? 12.7 t/(hm2.a)?Soil erosion intensity of traditional RUSLE model is generally high,soil erosion intensity of BP artificial neural network model is generally low,and results of RUSLE model based on SMA are moderate.The evaluation results are ideal.(3)The spatial differentiation characteristics of soil erosion in hilly areas of central Sichuan were clarified.The erosion intensity of Pinshan county lied in the southern study area and Yanting county located in the northwest corner is generally high,where moderate erosion to severe erosion account for a large proportion.The central study area mainly included Ziyang city,Zigong city,Neijiang city,the eastern Meishan city,and the western Guangan city,where terrain is relatively flat,vegetation cover is higher and erosion intensity mainly are mild erosion and micro-erosion.(4)The relationships between soil erosion in hilly areas of central Sichuan province and environment factors are exposed.The soil erosion differences of different land use types are obvious.The largest value of soil erosion index is 500.71 and its type is low coverage grassland.The smallest value of soil erosion index is 0.42 and its type is waters.The soil erosion index of different vegetation coverage in the study area are 10%-30%,<10%,30%-50%,50%-70%,70%-100%,which indicates the higher the vegetation coverage,the stronger the soil erosion resistance.The soil erosion index of different soil type is different.The soil erosion index of each soil type are sorted,from large to small is: soft soil,yellow soil,yellow brown soil,lime(rock)soil,hardened surface,purple soil,paddy soil,yellow cinnamon soil,new soil,fluvo-aquic soil.The soil erosion index of the hilly areas in the hilly area of Sichuan is influenced by elevation.Its value is higher and average value is 221.9.