Development And Assessment Of Soil Water Erosion Algorithm Based On GEE Platform In Loess Plateau

The problem of soil and water loss in the Loess Plateau restricts the ecological protection and high-quality development of the Yellow River Basin.In order to control the soil erosion problem,our country has implemented a series of ecological construction projects since 2000,such as returning farmland to forest(grass)project,terraced fields and warping dam construction,which made a remarkable change in recovery of the the ecological environment deterioration on the Loess Plateau.At present,There are two widely used methods of soil erosion assessment — — soil erosion remote sensing survey "three factors" method and Chinese soil erosion equation(CSLE)"seven factors" method,but the methods of soil erosion investigation are different,and the results are difficult to be unified and compared.GEE remote sensing cloud platform has massive image data and powerful cloud computing functions,which Can greatly improve the work efficiency of regional and global scale research.Therefore,based on GEE remote sensing cloud platform,this paper applied "three-factor" and "seven-factor" methods to evaluate the area,intensity and spatial distribution characteristics of soil erosion on the Loess Plateau from 1986 to 2020.Evaluation of the results analyzed by these two methods led to conclusions as follows:(1)Based on the "three-factor" method,the area of soil erosion on the Loess Plateau accounts for about 55% of the total area.Based on the "seven-factor" method and CHIRPS rainfall data,the soil erosion area of the Loess Plateau accounts for 43% of the total area.Based on the rainfall data of meteorological stations,the area of soil and water loss in the Loess Plateau accounts for about 35% of the total area.(2)Based on the "three-factor" and "seven-factor" methods,the interannual change of soil erosion area on the Loess Plateau from 1986 to 2020 showed a decreasing trend.In terms of spatial variation,the "three-factor" method was adopted.The results showed that the distribution area of intense soil erosion intensity changed to moderate and mild erosion intensity.Based on the "seven factors" method and the CHIRPS rainfall data,the results showed that the distribution area of intense soil erosion intensity increased before the conversion of farmland to forest(grassland)in the Loess Plateau.After the implementation of the policy,the area of soil erosion in the distribution area of soil erosion intensity decreased significantly.Based on the rainfall data of meteorological stations,the area of soil erosion in the distribution area of soil erosion intensity decreased significantly.(3)From 1986 to 2020,the extremely intense erosion area of Loess Plateau mainly occurred in Ansai and Suide of Shaanxi province,Luliang Mountains of Shanxi Province,and eastern Gansu Province.Moderate and intense soil erosion occurred in northern Shaanxi,western Gansu,southern Ningxia,Xinzhou and Jinzhong in Shanxi,Zhengzhou in Henan and Haidong in Qinghai.Moderate and mild soil erosion mainly distributed in Inner Mongolia,southern Shaanxi,northern Ningxia,Jingtai,Tianshui,Baiyin of Gansu,Lingbao of Henan,Datong,Shuozhou of Shanxi,etc.The greatest variation of soil erosion intensity was concentrated in the loess hilly-gully region.(4)Compared to "three factors" method,"Seven factor" method takes more factors that affect soil and water loss into consideration,but the two models both have their own advantages."Three factors" method,which combines three important factors of the influence factors of soil erosion,to some extent,reflects the potential soil erosion condition,certain areas for guidance is of great significance to the soil and water loss management and planning;The "seven-factor" method integrates more factors affecting soil erosion,and considers rainfall factors,soil factors and soil and water conservation measures more than the "three-factor" method,which can be directly used for quantitative assessment of soil erosion.