Simulation of event-based landslides and debris flows at watershed level |
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Authors: | Shou-Hao ChiangKang-Tsung Chang Alessandro C. MondiniBor-Wen Tsai Chen-Yu Chen |
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Affiliation: | a Kainan University, 1, Kainan Road, Luzhu, Taoyuan County 33857, Taiwanb Consiglio Nazionale delle Ricerche, Istituto di Ricerca per la Protezione Idrogeologica, 06128 Perugia, Italyc Department of Geography, National Taiwan University, Taipei 106, Taiwand Soil and Water Conservation Bureau, Nantou County 54044, Taiwan |
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Abstract: | A coupled model has been developed to simulate, at watershed level, landslides and debris flows induced by a severe typhoon (tropical cyclone) in Taiwan. The model comprises a landslide susceptibility model to predict landslide occurrence, an empirical model to select debris-flow initiation points, and a debris flow model to simulate the transport and deposit of failed materials from the identified source areas. In raster format with a 10 m spatial resolution, the model output includes unstable cells, debris-flow initiation cells, debris-flow velocities, runout paths, and deposition zones. The model was first tested and calibrated in a small area, where the damage by landslides had been investigated and recorded. It was then applied to a watershed, and the simulation results were validated by comparing them with a landslide/debris-flow inventory map prepared from satellite images using a multiple change detection technique. Model test and validation results confirm the usefulness of the model in predicting the number and size of affected areas (landslides and runouts combined), runout path, and volume of runout deposits. It is a common practice in Taiwan to separate landslide and debris-flow inventories and to study debris flows only in select drainage basins. This study suggests that landslide and debris flow should be modeled as a sequential process for efficient watershed management. |
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Keywords: | Landslide Debris flow Typhoon Debris-flow initiation points Coupled landslide-debris flow model |
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