Numerical Simulation of Tsunami Prevention by Coastal Forest with Several Species of Tropical Tree

Abstract

Tsunami prevention effects of coastal forest with several species of tropical tree have been investigated by one dimensional numerical simulation based on the non-linear long wave equations. The effects vary greatly with the species, the wood size and their combination. It is found that a coastal forest system consisting of 100m wide Rhizaphora apiculata woods in the water from the shoreline on the bottom of 1/200 slope, 50m wide mixed woods of Pandanus odoratissimum and Casuarina equisentifolia, and 50m wide Pandanus odoratissimum woods on the land of 1/100 slope can reduce the run-up height from 6.3m to 4.7m and the tsunami force at the end of forest from 14kN/m to 3.3 kN/m for a tsunami of 15 minutes in the period. The tsunami height at the shore line in case of no forest is about 5m.