|其他題名: ||A Study on the Geomorphological Change in Hoyenshan Nature Reserve|
geomorphological change;digital photogrammetry;digital terrain model;automatic image matching;soil volume analysis
|上傳時間: ||2014-09-12 16:24:25 (UTC+8)|
In this research, the Hoyenshan Nature Reserve at Sanyi was selected as the study site. This research utilized aerial photos obtained in four different years to investigate the soil erosion in the study area. Specific procedures of the research include: (1) to obtain coordinates of ground control points applying GPS surveying; (2) to collect data of topographic features using digital photo-grammetry; (3) to establish DTMs applying automatic matching techniques. Finally, by analyzing those DTMs, we quantify the soil erosion and establish a model for evaluating the geomorphological change within the study area. When applying automatic matching technique in collecting DTM points, the quality and percentage of overlap of the aerial photos usually affect the results. To obtain better results, manual digitization of break lines is required for those areas that have poor results in previous runs, then the interpolation is performed to generate regular DTM points. Automatic matching is based on the gray values of digital images, therefore, digital surface model (DSM) is obtained through the process. The results indicate that DSM can be used to derive drainage system and watersheds, the geomorphological change can then be e valuated by comparing the drainage systems and watersheds of different years. To estimate the volume of soil loss, however, the areas covered by forest should be excluded so that the computed volume is not affected by the tree growth. The geomorphological change of the study area is affected by many factors. More-over, the frequency, intensity, and locations are varying. Therefore, it is very difficult to model the geomorphological change. However, based on the volume and rate of soil loss, it is estimated that the unique geomorphologic features of the study area should still remain for a long period of time.
|關聯: ||航測及遙測學刊, Vol.5, No.1, pp.17-31.|