Analysis of Topographic Signatures after Typhoon Morakot-take Watershed of Southern Taiwan as Examples
碩士 === 長榮大學 === 土地管理與開發學系碩士班 === 100 === In the past the research of topography and landscape evolution, applied the Digital Elevation Model (DEM) and the scale was 40mX40m, focus on the long-term variation processes. The study areas including Chi-Shan River Basin、 Lao-Nong River Basin and Nanhwa Re...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2012
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| Online Access: | http://ndltd.ncl.edu.tw/handle/16925990494975634838 |
| Summary: | 碩士 === 長榮大學 === 土地管理與開發學系碩士班 === 100 === In the past the research of topography and landscape evolution, applied the Digital Elevation Model (DEM) and the scale was 40mX40m, focus on the long-term variation processes. The study areas including Chi-Shan River Basin、 Lao-Nong River Basin and Nanhwa Reservoir Watershed. The study takes Typhoon Morakot for example and uses 2 m Digital Elevation Model and Aerial-photos to analyze topographic change. A topographic index that is a composition of three different indexes to evaluate the model’s performance, that is Slope、Roughness index and Curvature.
The Hydrology tools of Arc-GIS are used to perform watershed delineation on a digital terrain model and applied Greeness to recognize the landslides on aerial-photos. The sampling data are extracting from catchment that has higher slump ratio. In order to evaluate the topographic evolution during typhoon events an automatic window program based on MATLAB is proposed to analyze topographic change.
The results indicate that slope and surface roughness has significant variation and the percent of variance up to 70 percent on disturbance area after event of Typhoon Morakot. According to surface roughness variation, the average and standard deviation of surface roughness in disturbance area are larger than the undisturbed area. In the Curvature analysis, using computational mesh of 15m x 15m and 10m x 10m to perform maximum and average of Curvature. The result was coincident with surface roughness analysis.
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