Comparison of Debris Flow Hazard Mapping between Empirical Function and Numerical Simulation-a Case Study in Taiwan

In this study we performed field investigation of a debris flow hazard event in eastern Taiwan, and conducted debris flow hazard mapping with empirical (SWCB guideline) and numerical methods (RAMMS::DebrisFlow). Finally we compared the mapping results with the damage of the housings and infrastructures, and discussed the applicability of these two methods. The preliminary inundation area following the empirical method is the greatest (13 Ha), after modification with local topography it reduces to 4.6 Ha. The numerical simulation result is the closest to the actual scenario. By applying the hazard degree classification based on velocity and inundation height, a hazard map is provided. The high hazard degree in the map matched with the damage status on the field, indicating that the hazard map could be used for land-use planning and local protection engineering purposes.