| Based on the scale principle,the study of soil erosion in time and space is the starting point and focus of domestic and foreign research.The hinterland of the Three Gorges Reservoir Area is the most serious soil erosion in the three gorges reservoir area(TGRA).Papers in reservoir area centre Kaizhou district,Yunyang district,Fengjie district,Wushan district and Wuxi district,as the research scope,in 1970 s,1988,2000,1988,2017,five times remote sensing image as data sources,using RS and GIS spatial analysis as a whole scale,watershed scale,villages and towns scale analysis of the three gorges reservoir area,the grid cell size four various scale hinterland of multi-scale space-time evolution law of soil erosion and its differences.Research shows:(1)The spatial-temporal evolution of soil erosion in the research area.The area of erosion in the study area was over 50%,erosion is widespread,and serious erosion areas are mainly distributed in the study area such as Middle East,southeast and southwest regions,especially the widely distributed and trough valley flat valley area.The spatial dynamic changes of the research area are divided into two periods: 1970-2000 and 2000-2017:1970s-2000,which is the period of deterioration of erosion,and the period of improvement of erosion in 2000~2017.It shows that the low erosion intensity of 2000~2017 has a large transfer area with higher erosion intensity,and the erosion area increases.From 2000 to 2017,it is the opposite of that,which means that the erosion area is larger and the erosion area decreases.(2)Different evaluation scales of soil erosion in the study area.In the basin scale,the area distribution of erosion intensity decreases with the increase of erosion intensity.The Caotangxi river basin,Meixi river basin and Pengxi river basin belong to the more serious erosion areas,and the Bianyuxi river basin,the hongyanhe river basin and the Xiaoxihe river basin is better.On the scale of towns and villages,severe erosion is mainly distributed in the west of the study area,Wushan,Wuxi and Fengjie three districts and along the Yangtze river.Over time,these areas appear to expand rapidly shrink after the evolution of the situation,but still relatively serious region for the erosion rate,this with its intense human activity and karst landscape ecological fragile areas.In the township of Baiqiao town,Jinfeng town,Houba town,Lingjiao township,Fengling town is the serious erosion area,belonging to the key governance area.However,some towns in Yunyang district are in a state of erosion and deterioration,and the governance of erosion should be strengthened.On the grid scale,more than 40 years ago,the river valley areas such as trough valley,Yangtze river and so on have been eroded seriously,and more attention has been paid to the flat areas with more human activities.Less erosion areas in the area of roughly unchanged,but is now shifting from the edge area of the east to the south and north,and a lower erosion agglomeration district soil erosion index from 0.51 in 1970 s is 0.15 in 2017,lower erosion region erosion condition also improved.(3)Variation of soil erosion at different scales.Volatility is a good evolution type of overall scale in study area,with further space scale,watershed scale has been deteriorating volatility and volatility good two types of evolution,the villages and towns scale and grid scale volatility is a good,deterioration of volatility,hots for better and worse four types.Different scales evolution trend and the change of the distribution of soil erosion on the subject,the overall level of different spatial scale as time has its irregularity,especially in the evolution trend and the overall evolution instead of erosion deterioration parts,but the main evolution type of these smaller space scale still reflect the evolution trend of area,and with the further expansion of scale,the evolution of the regional overall trend dominated the second level scale evolution type of direction.(4)The case study of evolution characteristics of soil erosion pattern in typical areas.The typical area is dominated by microscale erosion,and the structure of the patch is complex,and the concentration is high,and the degree of erosion is proportional to the diversity.Erosion is relatively simple structure,high strength type plaques concentration is lesser,but with the erosion degree good,erosion intensity is relatively high for the key area of human management,so the patch trends fragmentation,complex plaques distribution,high concentration.The erosion condition of Qixia town is continuous deterioration,relatively,the areas of erosion intensity are more evenly distributed,and the change of diversity is inversely proportional to the degree of erosion.Typical area of soil erosion intensity is mainly composed of dry land,forest land and grassland of the three categories,the erosion degree is the dry land > grassland > forest land,water,building land,paddy field erosion degree is small,the dry land more area,high degree of soil erosion,and erosion are more likely to be in a state of deterioration. |
PDF Full Text Request