Debris Flow Prevention Countermeasures with Urban Inundation in a Multihazard-Environment

抄録

Large-scale sediment-related disasters have been increasing in recent years [Uchida et al., 2009; Inoue and Doshida, 2012], such as the deep-seated catastrophic landslides caused by Typhoon Talas (T1112) in the Kii Peninsula, southwest Japan, in 2012. The formation and collapse processes of landslide dams strongly influence water and sediment runoff. When a large-scale landslide dam collapses, the peak discharge of downstream flooding can sometimes become several times as large as the inflow discharge upstream. Such abrupt increases in flow discharge often cause serious disasters in downstream areas. The objective of this study was to support prediction systems for hazards caused by debris flows. We developed a crisis management system to contribute to evacuation decisions and actions by providing information to residents. We adopted Hyper KANAKO as the basic tool of the crisis management system. This system can also provide results of temporal changes such as flow depth and sedimentation depth for the administrator. The time-series images are associated with a world file that responds to geographic information from a 2D topographic model. It is possible to check the simulation results on a GIS as soon as calculations have been performed. In addition to the existing system, we developed functions to reproduce the side-bank erosion caused by landslide dam overtopping. This new system requires setting the height of the landslide dam, the width of the river channel, the initial overflow channel width of the landslide dam, and the numerical constant for side-bank erosion velocity as calculation conditions. The system can display the widening of the overflow channel of the landslide dam caused by overtopping, and analyze a series of phenomena related to flooding from the overtopping erosion of the landslide dam. Moreover this system can assist in developing more effective countermeasures and hazard maps for disaster mitigation.

収録刊行物

  • 砂防

    砂防 9 (2), 58-67, 2016

    公益社団法人 砂防学会

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