Modeling Multi-Hazard: Landslide Initiation and Debris Flow
Date Issued
2010
Date
2010
Author(s)
Chiang, Shou-Hao
Abstract
Landslides are triggered by different causes including intense or prolonged rainfall. An efficient model for evaluating the hillslope hydrology is crucial to landslide prediction. Besides, not only landslides but also rainfall-induced debris flows also lead to devastations. Although many numerical models have been proposed to simulate the physical behavior of a specific debris flow event, current models have rarely incorporated regional landslides and debris flows into a single assessment framework. In addition, applicability of landslide model to watersheds is often impeded by insufficient data quality and data representativity, such as rainfall information and topographic data. ISOLAD (Integrated SOil moisture-LAndslide-Debris flow model) is therefore proposed to predict the development of soil wetness, landslide initiation and debris flow into an integrated modeling framework. Besides, radar data for estimating rainfall patterns and Monte Carlo simulation for evaluating parameter uncertainties are embedded into ISOLAD to assess the coupled landslide-debris flow hazard in mountainous area.
ISOLAD involves three major modeling components: the soil moisture model, the landslide model and debris flow model. This study first verified the soil moisture model by a small plot experiment. The landslide model and debris flow model were verified by simulating a past landslide-debris event. Further, ISOLAD was applied to assess the landslide-debris flow hazard for a 120 km2 Baichi watershed located in the northern Taiwan, where landslides and debris flows occurred frequently during typhoon seasons. For watershed scale application, two typhoon events, Typhoon Aere (2004) and Typhoon Haitang (2005), were use to calibrate and validate the ISOLAD respectively. Both two events obtained accuracy higher than 80%. However, the performance of ISOLAD can be affected by input data and DEM resolution (5 m, 10 m and 20 m). It is that the increase of grid size, the decrease of prediction accuracy, especially the prediction of failure timing. The result implies an inherent limit for ISOLAD application using different qualities of input data. ISOLAD is a novel approach for modeling the multi-hazard: landslide initiation and debris flow. However, test over various regions of climate, geology and topography are suggested to improve the applicability of ISOLAD.
Subjects
Landslide
debris flow
modeling multi-hazard
Monte Carlo simulation
Type
thesis
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