Estimation of Drift Woods Discharge From Rivers in the Ariake Sea by Their Transport Simulation

Abstract

The Northern Kyushu Heavy Rain in July, 2012 caused very serious damages. The event also caused many drift woods disasters in river basins and coastal areas. This research focuses on transport of drift woods in the Ariake Sea due to the rain event. Numerical simulation of their transport by 3D hydrodynamic model (DELFT3D) combined with assumed drift woods tracking model and comparison between the calculation result and collection data by Ministry of Land, Infrastructure Transport and Tourism were conducted. From the result, the followings were clarified: 1) total drift woods volume of discharged from all rivers into the sea was estimated as 17,500m 3 ; 2) volume of discharged drift woods from each A-class river was estimated; 3) relationship between the volume and specific maximum river discharge was evaluated.