Remote Sensing Dynamic Monitoring Of Soil Erosion In Chaohu Area

Soil resources are the material basis of human production and social economic development.China is suffering from a serious threat from soil erosion,which seriously threatens food and environmental security.It is of great significance to carry out research on soil erosion in Chaohu region for regional land use planning and ecological environment construction.In order to meet the needs of soil and water conservation and ecological environment construction in Anhui Province,this research takes the Chaohu region as the research object.We collected related data including climate,soil,DEM,and remote sensing images.This research selected the empirical model methods for different factors proposed by Wu,Williams,Liu,Wischmeier,Dai,and Fang were selected as reference.Furthermore,this research established a modified universal soil loss model(RUSLE)using GIS and RS technology,and to quantitatively evaluate the soil erosion intensity of the study area in 2007,2012,2017,and 2021.The dynamic characteristics of spatial and temporal for soil erosion in Chaohu region were explored by using transfer matrix,distribution index,center of gravity migration model,and trend analysis,respectively.Finally,the spatio-temporal distribution characteristics and driving mechanism of soil erosion in the study area were discussed using geographical detector.The results are as follows:(1)In the past 15 years,the soil erosion intensity in Chaohu area has not changed much.The micro-erosion level accounts for the largest proportion.The severe erosion and extremely strong erosion accounts for the smallest proportion,and mostly distributed in the western,southern,and northeastern hilly areas with an altitude of more than 100 m and the slope is above 10°.These regions are far away from the shoreline of Chaohu Lake,with an average distance of 30.2 km and a maximum distance of 51.0 km,which will not affect the water quality of Chaohu Lake in the short term.With the development of ecological construction projects such as the Ten-million-mu Forest Growth Project in Anhui Province,the total proportion of slight and mild erosion areas in the buffer zones of 1 km and 5kmfrom Chaohu Lake shoreline remained above 98%and 93%,respectively.And the area of extremely strong and above erosion levels accounted for less than 1%and 2%,respectively.The results showed that the comprehensive environmental managementlevel of the first-level protected areas in Chaohu Lake Basin is good,and the ecological protection effect is obvious.(2)The results of dynamic change analysisshowed that the soil erosion intensity insignificantly increased from 2007 to 2021.The area of slight erosion decreased by396.46 km~2,and the area of mild and above erosion intensity increased by 228.18 km~2,44.67 km~2,43.96 km~2,46.27 km~2,and 28.72 km~2,respectively.Among them,the area of erosion grade for moderate and above in the buffer zone of 1km of Chaohu shoreline is small.The area of erosion grade for moderate and above in the buffer zone of 5 km did not change much.The both two buffer zoneswere mainly the conversion between micro and mild erosion.The movement direction of soil erosion gravity center in 2007-2021 was’Southwest(6.91 km)-Northeast(10.40 km)-Northwest(5.74 km)’,and the whole direction migrates to the northwest.(3)The spatial distribution of different topographic position indexes showed that the micro-erosion was less affected by topographic factors,and it was distributed in areas with 1-4 topographic levels.The mild and above soil erosion intensity were mainly distributed in the terrain index 4-5 areas,especially the extreme intensity and severe intensity were greatly affected by the terrain.From the perspective of different land use types,the distribution of micro-erosion in different land types was little different.The mild,moderate,strong,and extremely strong soil erosion were mainly distributed in woodland and other land types.The severe erosion was mainly distributed in other land types,followed by forest land,and construction land,respectively(4)The results of spatial differentiation showed that the explanatory power of each driving factor to the spatial distribution of soil erosion in the Chaohu region was as follows:slope>topographic index>elevation>land use type>soil type>rainfall>vegetation coverage>population density>economic factor.The interaction between different factors showed a nonlinear enhancement or two-factor enhancement relationship.Among them,the interaction between vegetation coverage and slope factor had the greatest explanatory power for soil erosion(q=0.1530).The high-risk areas of soil erosion in the Chaohu region were mainly distributed in regions with rainfall of more than 1600 mm,slope of more than 25°,altitude of 300 m,vegetation coverage of 0.4-0.5,land use type of other land,and terrain index of 4-5.In general,the soil erosion intensity in research area is mainly micro-erosion.The terrain factor is the main factor determining the distribution of soil erosion,and land use type is the main factor driving the change of soil erosion.The interaction between vegetation coverage factor and slope factor has a higher impact on soil erosion.