A Research On 1:50000 Regional Soil And Water Loss Topographic Factors Based On DEM

Soil and water loss is the main factor leading to land degeneration. China is one of the most serious countries influenced by soil and water loss, and in China, and Loess Plateau is the most serious region of soil and water loss. Soil and water loss is the result influenced synthetically by climate, soil, topographty, vegetation, and artificial factors, and topographty is one of the most important factors. Researches of soil and water loss can be divided into three fundamental types: slope scale, small watershed scale and regional scale, according to the research scale. So far, the domestic and oversea researches are mainly based on slope scale and small watershed scale, and the researches on regional scale are few. Usually, we take large-scale data for the slope scale research and small watershed scale research, and take slope and slope length as the essential topographic factors. But in the regional scale research, because the slope and slope length extracted from small-research or low resolution DEM are different from the information extracted by high resolution DEM, there are much more information loss and error. In this paper, by the means of the theories of GIS, Geomorphology, Soil and water preservation, authors take 1:10000 DEM and 1:50000 DEM as the essential data, and analyze 1:50000 scale topographic factors of regional soil and water loss. This analysis of soil and water loss is based on the topography and physiognomy. To the limit of the data deficiency, this research hypothesizes LS extracted from 1:10000 DEM as true. We choose Relief, Plan curve, Profile curve etc. and erosion potential surface which is a new topographic factor advanced in the research as essential research factor, analyze the relationship between LS and these nine topographic factors extracted from 1:50000 DEM, and eventually reaches the best topographic factor fit for 1:50000 regional soil and water loss appraisement. Finally, with the help of soil erosion data and land use data, authors prove that erosion potential surface is the best one, and can be used as the essential topographic factor for 1:50000 regional soil and water loss.