| People live on the earth and keep relations to its terrain everywhere, since terrain information plays an important role in many disciplines such as geology, geography, hydrology, disaster monitoring and resource management, et al., the terrain data acquisition is always the key research points in survey and mapping related disciplines. As a Digital relief map, Digital elevation model (DEM), which contains various information of terrain structure and character, is the foundation data for quantitatively describing many spatial variations such as landform structure, hydrologic process and biological distribution et al.. Because the DEM data is the separate altitude figure, and each data itself cannot reflect actual surface characters of landform, which needs to carry on the terrain analysis on DEM. The terrain analysis is a process referring to applying terrain data directly or indirectly to derivate geographic product, meanwhile, which is an important means to recognize the terrain environment. At present, along with the GIS technology's rapid development, the technology of calculating topographic factors and gaining great deals of terrain information by making use of digital elevation model (DEM) is primary in practice.The terrain is the important influence factor in landscape diversity of structure and special patterns; furthermore, the terrain character usually becomes the determinant of great criterion in region distribution pattern. The majority of the land area in Chongqing is hillslope or mountainous area and there is few research on Chongqing land information statistics. At present, environment problem and soil degeneration like soil erosion are very important. Chongqing city was selected as the experimental region, this research carries on the calculation of terrain information based on DEM and obtains terrain factors spatial distribution characteristic. Based on the analysis of terrain and the understanding of terrain character, this research analyses the rules of landscape special pattern in landform. The main contents and results were summarized as follows:(1) United height and relief amplitude, this research measured off the geomorphologic types. First, calculated relief amplitude and measured off the geomorphologic types, which take height and relief amplitude integrated as foundation. Then, counted the area and percentage of each basic type, and finally, derived the basic geomorphologic classification maps which make use of the union of height map and relief amplitude.(2) This paper calculated all terrain factors which reflect the topographic and geomorphologic characteristic and analyzed the spatial distribution characteristic of the study area. The result of this computation indicated that the area of slope 0-5°accounts for 22.09% of the total area, mainly distributes in the west region that has hillslope and parallel mountains and valleys. The area of slope above 25°accounts for 18.37% , the gentle and pith slope 8-25°is the broadest distribution in study area and accounts for 49.11% of the total area. The smooth area in the study area accounts for 5.45%, but other aspects do not have the obvious different and compare to average. The analysis on elevation frequency shows that the area of elevation 200-300m regional is the biggest and accounts... |
