| Summary: | 碩士 === 華梵大學 === 環境與防災設計學系碩士班 === 100 === Due to large landslides occurred in the upstream of watersheds to result debris-flow disasters from the attack of Typhoon Morakot in the Shinkai area in the southern Taiwan, in the paper, three watershed areas- Hongshuixian, Neighborhood 23 and Dafo are selected as our case study, and the FLO-2D model are used to work on the studies for debris-flow simulation.
Firstly, basic data collections of the watershed areas, as well as the rheological property experiments on debris flows are conducted. Secondly, to study the inflow hydrographs that will trigger debris flows under the condition of high landslide rate for the watershed areas. The paper uses the rainfall thresholds to determine the inflow hydrographs. When the cumulative rainfall (R) is greater than 200mm within 24 hours, it is seen as flooding, the given volumetric sediment concentration cv=0.1; when the rainfall intensity (I) is greater than 40mm/h, as well as the cumulative rainfall (R) is greater than 200mm, it is seen as landslide, and the given cv=0.65~0.8; from the occurrence of debris flow to the end of debris flow, the given cv=0.48~0.55. Finally, to make investigation of the influences of different inflow hydrographs, Manning’s n roughness coefficients, and sediment concentration on the flow depth and the inundation area of debris flow. Moreover, to further make comparison between the data simulated results and on-site survey data, in order to determine the conditions, such as the inflow hydrograph and resistance parameters for the three watershed areas. The simulation approaches proposed in the case study, including the simulation process, inflow hydrographs and resistant parameters, are able to work as reference for later debris-flow simulation or debris flow hazards mitigation.
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