Study On Dynamic Changes Of Soil Erosion In The Three Gorges Reservoir Area Of Chongqing Using Remote Sensing And GIS Technologies

Soil erosion is the main reason for destroying land resources and causing land degradation,and is also an important factor causing the deterioration of the ecological environment.Therefore,it is a great significance to carry on soil erosion research.After the impoundment operation of the Three Gorges Project,that will provide benefits to human beings,but also brought great changes to the original soil erosion pattern of the Three Gorges reservoir area.This study base on the RUSLE model,analysis the soil erosion of the Three Gorges Reservoir Area of Chongqing using Remote sensing and GIS technologies from 2004 to 2017.This research will analysis the spatial and temporal distribution characteristics of soil erosion,the correlation of soil erosion and geographical environmental factors,and the dynamic changes of soil erosion based on landscape pattern which in order to provide a scientific basis for the implementation in soil and water conservation policies of Chongqing.The main results are as follows:The paper based on the RS and GIS technology to calculate soil erosion factors with RUSLE model,and briefly analyzed the distribution and dynamic changes of various factors.There have six factors were multiplied to obtain the spatial distribution map of soil erosion in the Chongqing section of the Three Gorges reservoir area in 2004 and 2017.Using GIS technologe,we can analyze the spatial and temporal distribution characteristics and the transfer of each soil erosion type in the Three Gorges Reservoir Area of Chongqing from 2004 to 2017.In order to derive the law of change,the two-stage soil erosion intensity distribution map is superimposed with the geographical environment factors such as slope map,aspect map and annual average rainfall distribution map.Basing on the Fragstates4.2.1 ecological landscape software,analyzed the soil erosion wetland landscape pattern on class level and landscape level in the Gorges Reservoir Area of Chongqing.The results on the whole shows that :(1)The spatial distribution of soil erosion in the three Gorges Reservoir Area of Chongqing showed that: The middle and lower sections of the Yangtze River are mainly distributed with moderate,strong,extremely strong and severe soil erosion.The upper part of the Yangtze River is mainly dominated by mild erosion and mild erosion.In the times distribution of soil erosion showed that: The soil erosion area in The Three Gorges Reservoir Area of Chongqing presents a decreasing trend from 2004 to 2017,and soil erosion area is greatly reducing.(2)The main transfer direction of various types in soil erosion shows the trend that intensity weakening from 2004 to 2017.(3)The soil erosion is well correlated with slope.In general,when the slope is increased,the intensity of soil erosion always increase.The phenomenon of soil erosion mainly happens on the steep slope greater than 15°.(4)The effect of slope on soil erosion is more obvious than aspect.With the increase of soil erosion intensity,the influence of slope direction on soil erosion is gradually increasing.The soil erosion intensity on the northwest aspect and the north aspect in the study area is slightly larger,and the southwest slope and the south slope are slightly smaller.(5)The soil erosion in the study area shows an obvious vertical differentiation characteristic: The soil erosion mainly occurs in the low mountain and hilly regions with an elevation of 200m-1500 m.The main elevation range of soil erosion in 2017 is more narrow than 2004.(6)The soil erosion mainly exists in purple soil,yellow soil,limestone soil distributed areas.(7)The soil erosion mainly concentrates in the regions where average annual rainfall are between 1000 mm and 1300 mm.However,the soil erosion distribution is relatively small where average annual rainfall are between 1300 mm and 1400 mm.(8)In terms of class level: The mainly landscape types in the study area are moderate,mild and slightly erosion.The slightly erosion in the degree of fragmentation have decreasing,which in the degree of division have increasing,and the shape of the plaque became more complicate from 2004 to 2017.The slightly erosion was greatly influenced by humans.(9)In terms of landscape level: The various types of soil erosion patches continue to merge into larger patches.The SHDI and SHEI are decreasing which changes indicate that the landscape heterogeneity is reducing.(10)In the study area,soil erosion which in the farmland mainly occurs in the slope of 0°-5°.The slightly erosion is the dominant landscape type in the region.The slope in 5°-8° which plaque shape is the most regular,and the slope range of 8°-15° have the best connectivity between plaques.The landscape heterogeneity has reduced in all farmland from 2004 to 2017.