NUMERICAL SIMULATIONS OF INUNDATION FLOWS WITH FLOOD CONTROL SYSTEM IN IIZUKA CITY AND EXAMINATION OF ITS EFFECTS ON FLOOD HAZARD MITIGATION

Abstract

Numerical simulations of flooding event in the Iizuka-city area in the Onga river basin was performed by a numerical model for rainfall-runoff in watershed and flood inundation process in urban area with flood disaster-reduction system such as sewer network and drainage pump station. The rain-fall runoff was simulated by a distributed hydrological model. The flood flow in rivers and inundation flows on the ground were simulated simultaneously by the 2D free-surface flow model. The dynamic network model for free-surface-pressurized flow combined with the Preissmann slot was used for the sewer network. The effects of flood disaster-reduction system and inundation processes in Iizuka-city under different rainfall patterns were examined based on the numerical results.