The Calculation Of Urban Soil Erosion Based On GIS

As the development of the soil and water loss, the urban water and soil conservation was concerned widely. Serious soil erosion was brought by the accelerating urbanization. So, there is an important theoretical significance of local soil erosin control and to realize ecological recovery to study the characteristics of soil and water.The study based on the WuHan in jianghan plain as research object. By research area rainfall,topography and soil allele data base, we analysed the the general situation of soil and water loss of water and soil conservation status quo and different areas of soil erosion of types of land use soil erosion situation and other aspects of the urban soil erosion characteristics by used GIS and RUSLE model, and estimated the potential soil erosion and the various land use type of soil maintain ability. At last, we advancesd some measures about soil erosion control based on the characteristics of studied area of soil erosion and various kinds of soil in capacity characteristics. The main conclusion as follows:(1) The average soil erosion modulus is 2075 t/km2 a, and belong to mild erosion level promulgated by the ministry of water resources. It is far outweigh the creterion soil loss tolerance of 500 t/km2.a at earth-rock moutains at southwest enacted by Ministry of water resources. The mild soil erosion area Present a decreased obviously trend for 399.44 km2 in four years, and the Moderate and strength area present a small decline for 16.37 km'and 1.82 km2.It account for that there is outstanding achievement at soil and water conservation this yeres at research yeres, but the focus of soil and water conservation are mainly concentrated in strengths the following erosion treatment, and the task of controlling soil and water loss is still very arduous.The intensity of the research in land area more than the total area accounts for only study area, and its erosion 1.53 percent of total regional erosion has accounted for 26.94%.The extremely strength and intense erosion area, with a certain degree of increase respectively km2 and increased 1.13km2,is the human activity intervention section strong in quarrying, quarrying, urban construction, basic construction land is important to manage area. In addition, medium, mild erosion grade erosion area represents a significant proportion, the proportion of all this part erosion area is mainly the dry land fields, the unreasonable utilization leads to its governance also can not be ignoren.(2) From the soil and water conservation areas, the soil erosion modulus of key supervision area for 1230 t/km2·a, and is belong to mild erosion, focusing on the soil erosion modulus ecological environment 2780 t/km2·a, and is belong to moderate erosion, key prevention reserve of soil erosion modulus 1013 t/km2·a, and is belong to moderate erosion. Key area of the erosion ecological environment of erosion is 58.62%, but the erosion of the total amount of 78.70% region erosion. Extremely strength and intense erosion mostly in soil and water conservation supervision area, and this is city infrastructure frequent area. Therefore, the unreasonable construction of city basic development is the main reason of soil and water loss research area. So, the soil and water loss work of soil and water loss ecological environment was not good, and need to further efforts.(3) According to erosion area, erosion intensity and the distribution of erosion, various types of land use are in the decreasing trend of dry fields, shrub land, forest land, urban land, industrial and mining land, grassland and unused land. Upland fields are in account of 60.16% of the total area of erosion. Paddy field is mainly in the degrees of tiny erosion, and dry land in moderate erosion.. From the erosion amount, the dryland account for the largest percentage of 80.58% of soil erosion amount, followed by 5.25%, and 5.01% in traffic mineral land and unused land of study area, and the proportion of other types is very small. This indicated that dry land and traffic mineral land is the main land use types which influence the soil erosion of study area. Annual soil erosion of dry land and traffic mineral land were 2555749.0 t/-a and 166428.6t/-a, respectively, which belong to light degree of erosion. If the erosion degree can be reduced to tiny degrees, the soil erosion of study area could reduced at least 100 million t. Therefore, the key countermeasure to control soil and water loss is the rational use of dryland and mineral land.(4) From the overall view of potential erosion and actual erosion, the study area had a relatively strong capacity of soil and water conservation. The dryland field had relatively larger erosion area and slope, resulting in potential larger total erosion amount. From soil maintain ability (soil keep modules with actual than the erosion modulus), the paddy land had the largest maintenance ability of 7.80,7.13,7.72, followed by shrub, forestry land and grass land with the ability above 1.62,2.57,2.61. And dryland, unused land and traffic mineral land had wores keep abilityof 5.17,5.17 and 4.43, respectively.Because of the flat topography, good water conservation measures and slightly eroded, the paddy soil had the strogents maintain ability. Forest land and grassland also had stronger maintains ability because study area had increase afforestation, city urban greening area and quality, and belong to mild erosion.Forest land had stronger maintains ability because, first of all, forest canopy can greatly buffer raindrops kinetic energy, make its role in soil strike splashing greatly decreased; Secondly Forest land tree branches and leaves layer can reduce the raindrops splash erosion role and has the interception and block runoff role; The roots of the forest trees again has the role of solid earth soil, and can improve the ability of soil water infiltration performance and the antipunching corrosion resistance. Unused land had the weakest soil maintain ability as it is bare and no vegetation, also lack of effective water and soil conservation measures.(5) The dominant factor of soil erosion in research areas is the area of land used type. It means RUSLE equation depends on land use types of vegetation coverage management and water and soil conservation measures two factor in the study area the changes caused by soil erosion is obviously influences. Therefore, the key of controlling research area of the prevention and soil erosion is to adjust the structure of land used. We need to redevelope and management the vegetation coverage low soil and water consercation measures of poor reasonably transformation. Allocate ditch, pool water system and pavement such slope engineering in dry fields in order to achieve flood control, reduce erosion, irrigation, convenient farming and the requirements of economic hidden, except water and soil conservation forests desertification and all the farmland and beyond, take ditch ridges planting, cross-sectional slope farming, increase crop index and other measures, water, reduce soil water and soil loss, soil and water conservation measures and the city center is mainly to the lakeside, roads, development and construction project, levee, hydraulic engineering and urban residential areas complementary with necessary engine zering measures and conduct afforestation.