Numerical Study on Tsunami Propagation into a River

The Tohoku Earthquake and Tsunami in 2011 caused serious damage not only to coastal structures, but also to riverine infrastructure due to long distance of wave propagation into rivers located on the coast facing the Pacific Ocean. Although there have been numerous investigations on tsunami, limited number of studies have been made for tsunami propagation into a river channel. This study investigates tsunami propagation into a river numerically by comparing with laboratory experiment data. The present numerical simulation is based on shallow water equations, which are solved with the MacCormack scheme. Difference between calculated and experimental results are evaluated in terms of root mean square error. It is concluded that the present numerical simulation yields good agreement with experimental data in a wave flume. In addition it is observed that geographical characteristics in the river channel, such as sandbars and estuarine sand spits, highly affect tsunami propagation process in a river, causing lowering water level along with late arrival of tsunami peak.