Study On The Soil Erosion By Using GIS In Upstream Region Of Lishui Basin,Hunan

The problem of soil erosion is one of global environmental problems,it is also Chinese major environmental problem.The study based on the upstream area of Lishui basin in Hunan as the study area. Based on rainfall, topography, soil and other data in the study area, using soil science, ecology, soil and water conservation and other related theories and methods, using Geographic Information System (GIS), remote sensing (RS), Global Positioning System (GPS) and other methods as the technology platform, carrying out soil erosion environmental factors survey by field investigation and laboratory determination, using RUSLE model to classify the level of soil erosion. On this basis,the study proposed measures to control soil erosion in the region. The study results can be applied to the northwestern of Hunan mountain eco-construction planning, small watershed management, agricultural planning, land use planning and other fields. This article gets the conclusion as follows:(1) Through analysis and calculation, the average soil erosion modulus of the upstream region of Lishui basin is867t/km2·a, and belong to mild erosion level. It is outweigh the permissible soil erosion modulus of500t/km2·a at hilly red soil region of southern China enacted by Ministry of water resources, and the task of preventing and controlling soil erosion is still very arduous.The study area which above strong erosion accounts for2.94%of the total area, but its erosion accounted for22.58%of total erosion, and it is mainly caused by human activity, such as steep slope farming and irrational land development and construction. In addition, moderate erosion and mild erosion area is also large, the main reason is the unreasonable development and utilization on dryland, this part is also need to focus on governance.(2) According to erosion area, the amount of erosion and erosion intensity, woodland is the largest class of various land use types in soil erosion area in the study area,its erosion area is7283.14km2and it accounts for53.94%of the total area of erosion. Followed by water, shrubs, dryland and grassland, accounted for13.10%,12.45%,11.03%and9.07%of the total area of the soil erosion. Construction land and bare rock area is small in the study area, so the percentage of soil erosion area is small. From a variety of land use types in erosion,the proportion of woodland account for the largest percentage of 49.77%of soil erosion amount, followed by dryland, accounting for the percentage of32.32%for the study area, and the proportion of other land use types is very small. So we can see woodland and dryland is the main land using types which influence soil erosion of the area. Thus, the key to control of soil erosion is the reasonable use of the region’s woodland and dryland.(3) From the potential erosion amount and the actual amount of erosion, the ability of soil and water conservation in the study area is strong.From soil conservation ability, the largest soil and water conservation capacity of land use type is grassland, scrub and woodland, respectively7.66,7.02,5.75, dry land and bare rock at the weakest, its value is1.87and2.25respectively. The soil conservation capacity of dryland and bare rock is weak,because the land surface is exposed and without vegetation protection,and lack of effective measures of soil and water conservation.The soil conservation of land for construction is also weak,because the construction land is unreasonable development and utilization, and the terrain is steep.(4) Land use types of the study area is the impact of the determinants of soil erosion in the region.The vegetation coverage factor and water and soil conservation factors in universal soil loss equation(RUSLE) mainly depends on the area of land use types. So the key to reduce the amount of soil erosion of the study area is optimizing land using structure of the region. According to the actual situation the region should increase its coverage of vegetation and soil and water conservation measures. The region should be allocated soil and water conservation engineering measures and plant measures rationally to reduce surface runoff, and increase the surface infiltration and reduce soil erosion. The existing woodland and grassland should be allocated and transformed rationally, to achieve a combination of trees, shrubs, grass, and enhance the landscape features and soil conservation function of the region.(5) By drawing on the domestic areas with similar soil erosion control experience, according to current situation of soil erosion and land use structure of the study area.As controlling water and soil lossing. gradually adjust the land use structure, deploy water and soil conservation measures reasonably, and form a relatively complete system of soil erosion prevention and control measures. This article studies from the elevation distribution level, divid the study area into mountainous, hilly and gully region and plain hill hill district, according to different characteristics of regions to formulate soil and water conservation measures to control the area of soil erosion. It can effectively reduce the amount of soil erosion in the basin, it also has some guiding significance to soil erosion controling and ecological construction in the basin.