| Water and soil is currently one of the main research topics of environment change, and it have affected the survival of human being and sustainable development. In a regional scale, applying RS/GIS technology to investigate the status of soil erosion and its dynamic changes, which provided scientific protection for eco-environment construction and soil and water conservation planning.This paper based on RS/GIS technology and the Revised Universal Soil Loss Equation (RUSLE), and took Ninghua county as study area, taken remote sensing images of Landsat in three periods(2001,2007 and 2013) as the main information sources, together with digital elevation model, monthly precipitation data for three years, soil maps and the investigtion datas of the plots. These data were calculated for slope length and slope steepness factor, vegetation cover management factor, soil erodibility factor, rainfall erosivity factor and support practice factor. And then, using RUSLE model to estimate soil erosion in 2001,2007 and 2013 three periods,while combined with GIS spatial analysis method to discuss temporal and spatial dynamic changes.In order to further analyze variation of Ninghua soil erosion intensity in different periods, this study investigated the variation tendency of soil erosion intensity by the effect of land use class, topographic factors (elevation and slope) and vegetation coverage factors.The results indicated that RUSLE model based on RS/GIS technology could be extended to estimate regional soil erosion,and provided effective technological means for quantitative analysis of regional soil erosion.The total area of soil erosion in Ninghua had decreased from 408.86km2 in 2001 to 317.79 km2 in 2013.Nearly twelve years, the total area of soil erosion decreased 92.67km2, the result showed that the extent of soil erosion assumed a declining trend. From the topographic factors point of view, soil erosion concentrated in relatively low altitude areas.the most serious of soil erosion distributed in the elevation zone of 200m-400m, and the largest area of soil erosion distributed in the slope degree from 8°to 15°. From the land use point of view, the result indicated that bare land, garden plot and shrub exhibited relatively higher soil erosion ratio, in contrast,the ratio of soil erosion in forest was low, which forebode planning trees would benefit to soil conservaton. From the vegetation coverage point of view, the maximum value of soil erosion ratio in Ninghua appeared inside the area with vegetation coverage between 10% and 30%, when vegetation coverage greater than 90%,the area and ratio of soil erosion reached the minimum.On the whole,there was significantly negative correlation between soil erosion ratio and vegetation coverage in Ninghua county. |
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