Digital Terrain Analysis Of Malian River Basin Based On DEM

Digital Evolution Model (DEM) is one of the most important part in the spatial database, the DEM has been adopted in many scopes digital topography analysis is a kind of digital technology to analyse the property of topography and distill the characteristics, which is based on DEM image. This kind of technology can provide more basic theories and practices to analyze the topography in wide scopes. The resolution of the DEM image could result some great differences for the capacity of geo-information and precision of the Geo-information etc.This study is focusing on Malian River watershed which is located on LongDong Loss Plateau; a DEM of the watershed will be constructed. To distilling and analyzing topography characteristics by using different horizontal resolution of the DEM image would provide basic digital topography information to do researches on the influences of the topography and hydraulic characteristics with different horizontal resolutions of the DEM image in Malian River watershed.a) With the same scale, the topography can be ignored along with the low horizontal resolution of the DEM image and the modeling precision for the topography is getting lower as well, so that it influences the slope gradient negatively. However, it does not influence the direction of the slope too much, the quality of slope direction image is getting lower; the variability parameters of slope gradient and slope direction are getting lower; the precision topography characteristics is reduced, and the ground curvature ration can be ignored gradually, so that it is hard to reflect a realistic ground curvature situation.b) Along with the reduction of DEM image horizontal resolutions, the amount of rivers are decreased in the watershed, the total distance of the river is getting shorter; the catchment area of the smallest valley is getting larger, the fragmentation of the watershed is getting lower; with the same threshold value, the watershed area becomes smaller continuously, the amount of fragmentations of the watershed are reduced; the much more complicated hydraulic system, more detailed stream grid and more fragmented catchment can be resulted with high resolution of the DEM image.c) The watershed area, watershed roundness ratio and the valleys intensity in SSC watershed are selected as major classification factors. The tiered classification method is used to construct a standard framework for tree classification. 52 sub-catchments will be classified as 8 types of watershed in accordance with the topography characteristics in the Malianhe watershed.