Hitoshi Tanaka
Tohoku University, Japan
Title: Tsunami Propagation into Rivers; Problems and Solutions
Biography
Biography: Hitoshi Tanaka
Abstract
The 2011 Great East Japan Earthquake Tsunami overflowed existing embankments along Japanese coasts, and inundated the coastal area facing the Pacific Ocean. The maximum tsunami run-up height attained as high as 40m. Because of so extreme energy, tsunami propagated far upstream of rivers as well. The maximum tsunami run-up distance in a river was 50km observed along the Kitakami River located in Miyagi Prefecture, resulting in serious damages to riverine structures. In addition the tsunami propagation into the river and subsequent return flow caused considerable change in river topography such as erosion of sand bar and sand spit at the river entrance. Although there have been so numerous number of studies dealing with tsunami behavior in the sea area, limited number of investigations have been made for tsunami in rivers. The main objective of this lecture is to introduce hydrodynamics of tsunami ascending rivers, resulting riverine disasters, and also countermeasures.