RETENTION AND TRAPPING BEHAVIOUR OF TSUNAMI INDUCED LARGE DRIFTWOOD IN TRANSIENT FLOW CONSIDERING DIFFERENT HYBRID DESIGNS

抄録

 Destructive tsunamis can damage vegetation and produce tsunami induced large driftwood (TLD). Recent studies have elucidated mechanisms to control the damage of TLD. These methods include inland forests to trap TLD, and the use of an embankment and or moat structures, to reduce the impact velocity of the TLD. This study further investigated the function of hybrid designs and an inland forest in retaining and trapping of TLD. An embankment-moat design, downstream of a vegetation patch showed retention of TLD as well as rotation of TLD. This rotation encourages trapping of TLD by a downstream forest. This benefit in the rotation is especially noticed in tall driftwood models. Embankment-moat design, considering a long period wave, typical to that of a tsunami, then shows the ability to control TLD related damage.