DEVELOPMENT OF A SIMULATOR FOR FLOOD DAMAGE MITIGATION, AND INVESTIGATION ON FLOOD DAMAGE MITIGATION EFFECTS OF FLUVIAL WOODS ZONE

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A numerical simulator was developed for simulating complex inundation processes by river water and inside a levee in urban area as well as analyzing economic evaluation of flood control measures. The simulator comprises(1) a distributed hydrological model for simulating rainfall-runoff process in watershed,(2) a 2D unsteady free-surface flow model, based on flux-difference splitting scheme and unstructured finite-volume method, for flood flows in rivers and inundation process,(3) a dynamic network model, based on flux-difference splitting scheme combined with the Preissmann slot, for sewer network, along with(4) inundation economic survey. The simulator was tested against the observed inundation processes in the Iizuka-city area in the Onga river basin in the Kyushu storm disaster in 2003, and then several simulations, which include inundation processes under hypothetical rainfall patterns, effects and economic evaluation of flood control measures and so on, were conducted. In addition, the effects of the fluvial wood zone in landside on overflow characteristics of flood flows were investigated experimentally, theoretically and numerically. A discharge formula, that includes both effects of characteristics of the wood zone and levees, was developed and validated through experimental and numerical investigations.