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.
by Japan Society of Civil Engineers