Study On Spatial Distribution Pattern Of Soil Erosion And Its Relationship With Environmental Factors In Shitai County

Soil erosion is not only seriously damaged the land-based natural resources, but also causing serious ecological and environmental problems. A great threat to sustainable development was caused by soil erosion. Shitai County is located in mountainous areas in southern Anhui and the mountainous area accounts for more than 80%. The phenomenon of soil erosion is very serious because of the dual role of natural factors and human factors in Shitai. We must take greater efforts to control soil erosion and achieve ecological, economic, and social coordination of sustainable development, if we want to accelerate economic development and to change the status of poverty and backwardness. A scientific basis and decision support for soil and water conservation planning could be provided to soil and water conservation department by studying spatial distribution pattern of soil erosion and its relationship with environmental factors in Shitai County. It could play a positive role in sustainable development of the environment and economic in Shitai County.A soil erosion database of Shitai was established based on the landuse maps, soil type maps, remote sensing images, SRTM elevation data and weather information and the use of ERDAS IMAGINE8.5 and ArcGIS software. The spatial distribution of soil erosion was revealed and the relationship between the environmental factors of soil erosion and soil erosion were analyzed. The spatial correlation between the environmental factors on soil erosion and soil erosion intensity were analyzed by the use of information entropy model. The following are the main conclusions:(1) The total annual erosion of Shitai County is 2850069.39 t / a. The amount of the annual erosion of different grades are in descending order of moderate, mild, strong, very strong, micro-degrees, severe erosion. The amount of annual erosion were followed as 791848.52 t/a,652615.31 t/a,345649.93 t/a,64903.73 t/a and 21401.27 t/a. Moderate erosion is the largest and proportion of the total erosion accounts for 34.16%.(2) The soil erosion area of each grade in Shitai County descended as: mild, micro-degrees, moderate, strong, very strong and severe erosion. The erosion area was followed as 586.05 km~2,402.79 km~2,276.18 km~2,105.27 km~2,35.31 km~2 and1.26 km~2. The proportion of the total erosion area were respectively as 41.66%,28.63%,19.63%,7.48%,2.51% and 0.09%.Mild degree of erosion and micro-erosion are the main erosion level type in Shitai County.(3) Different grades Erosion was scattered in spatial distribution. Hengdu, Qidu, Dayan and Xianyu Town are the serious region and the moderate and above level erosion area ratio are in excess of 32%. The situation of soil erosion in Dingxiang, Renli, Jitan and Xiaohe Town are in a lower extent.(4) The following are the relations of the spatial distribution pattern of soil erosion and environmental factors:①The elevation zones of 200 ~ 500 meters account for the largest area of soil erosion in different elevations. Moderate, strong, very strong degree of soil erosion mainly occurred in the 200~ 500 meters elevation band and gradually reduce in upward, downward of this band;The distribution of the erosion proportion of Various elevation zones is consistent with the area ratio.②15°~ 25°slope account for the largest area of soil erosion in different slope zones; But 25°~ 35°slope is the largest amount of soil erosion and accounting for 35.56% of the total erosion; Moderate, strong, very strong soil erosion were respectively mainly occurred in the 25°~ 35°, 25°~ 45°and 35°~ 45°slope, and the amount of soil erosion were decreasing as their respective center of upward, downward.③The Southern Slope which accounting for 14.19% in total erosion area is the largest area in different aspects, and followed by the North Slope. North Slope soil erosion is the largest area which accounting for 22.87% of total soil erosion and followed by the Northwest Slope.④Woodland accounting for 64.85% of the total area is the largest soil erosion area in a variety of land use types and followed by grassland; The soil erosion proportion of land use types are basically in line with the erosion area ratio.⑤The soil erosion area of the various soil type are descending as followed: red soil, limestone soil, yellow soil, yellow brown soil, rice soil, stony soil; Red soil's erosion amount is the Largest , intensity and above the intensity of soil erosion mainly occurred in the limestone soil.⑥The spatial correlation of soil erosion affecting factors and erosion intensity were analyzed by using information entropy model. The spatial correlation expects Hengdu and Dayan Town was ordered as follows: slope>elevation>land use >soil type>aspect. Slope and elevation take a greater impact on soil erosion. Relevance of aspect is the smallest in the five factors. The correlation of land use patterns or soil types and soil erosion intensity achieved a maximum value in Hengdu Town. That shows land use patterns and soil types are the dominant factor which caused soil erosion in Hengdu Town.