Research on the Basic Geomorphology Form of Chengdu Based on DEM

Based on ASTERGDEMV2 version of the 30 m×30 m resolution DEM data of Chengdu, the model was established for the terrain undulating volume extraction by neighborhood analysis in ARCGIS10.2 The terrain undulating degrees of the rectangle neighborhood windows of different sizes were extracted in the city, and the best calculation unit was determined by means of mean variable point analysis. On this basis, the map of terrain undulation was gotlen by spatially combining the best calculation unit with the elevation classification map directly extracted by arcgis10.2 in order to get the basic landform map of Chengdu.The results showed:that the optimum calculation unit of terrain undulation in Chengdu was 14×14 mesh size (176 400 m²). The terrain was mainly undulating and below, with an area of 98.54%. There were 20 types of basic geomorphologic forms in the city, of which 5 were the main types, with an area of 96.52%. Aceorotny to the spatial distribution pattern, in northwest of Chengdu. The Longmen mountains displayed variety of terrain fluctuations, and there were 13 types of undulating and varied terrains. The low-altitude hilly types were mainly concentrated in the Longquan mountains and the joint region between the Longmen mountains and Chengdu Plain, with a sporadic distribution in the middle and east of Chengdu. The two main types of low-altitude plain and low-altitude platform were mainly distributed between the Longquan mountains and in the southwestern part of the Longquan mountains.