Debris Flow Simulations Due to Landslide Dam Outburst and Considering Effective Countermeasures

Abstract

Recently, deep-seated landslides, DSLs, have become more frequent due to heavy rain events. Due to DSLs, there have been some cases of landslide dam formations in mountainous regions. When landslide dam outburst occurs, large scale debris flow might devastate the downstream area. Therefore, debris flow scenarios, arising from landslide outbursts, are studied to predict and prevent the damages in the downstream regions. In this study for the purpose of simulation, we applied the Hyper KANAKO system with the digital elevation model, DEM, taken before and after the landslide dam formation. First, we simulated the landslide dam outburst scenario by comparing it with the downstream deposition. When the sediment diameter and the fluid phase density were set to 0.2 m and 1,000 kg/m3, respectively, the results were satisfactory. Then, we considered an effective countermeasure installation in the torrent by setting one closed type sabo dam with an effective height of 15 m. We found that setting the sabo dam in the downstream side of the torrent prevented the sediments from moving downstream; this setup effectively prevented the damage. Therefore, simulations are useful for landslide dam outburst hazard mapping and for effective countermeasure implementation.KeywordsDebris flowSimulationLandslide damHazard mappingCountermeasure