A Study of Applying River Course Elevation Time and Space Variation to Assess Hazard Degree of Riavers
| Autor: | Wei-Lun Lo, 羅偉倫 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 On August 8, 2009 Alishan county area was devastated by Typhoon Morakot. The typhoon caused massive movement of the debris in Alishan Stream’s upstream catchment area. Great amount of derbis accumulated in the river course. The process of the derbis movement caused serious damage to villages, roads, cultivated lands, and public utility in the catchment area. In order to quantified damage under the derbis movement, this research utilizes aerial images to create digital terrain model. The landform data of 1996, 2005, and 2009 are rebuilt. Plane spatial analysis and longitudinal spatial analysis are both performed to analyze the river system’s variation through the river system itself and the river bed appearance; the latter is mainly to find out the vertical difference regarding the river course, the change in earth and rock’s quantity, and also to examine the lengthwise section and the cross profile of the river course. This study mainly focuses on the lengthwise section for longitudinal spatial analysis, and stream length-gradient index (S-L Index) are used as auxiliary tool. According to the result of this study, from 1996 to 2005, the river course stack was approximately 1,550,000 cubic meters between She Xing Bridge and 150 meters upstream from the Lai Ji Bridge along Alishan Stream; from 2005 till 2009 after the typhoon hit, the river accumulation jumped to about 11,360,000 cubic meters in the same area, which shows Alishan Stream has accumulated derbis in a great amount since Typhoon Morakot hit Taiwan. Through evaluating the river course’s present situation, the following-up government plan may be brought into discussion. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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