Analytical Model for Concave Shoreline Induced by the 2011 Tsunami

The 2011 tsunami induced sandy coast breaching in Akaiko area, Miyagi Prefecture, Japan. It also caused severe erosion of sand barrier-lagoon system adjacent to a river mouth on Sandai Coast in which Akaiko is located. These damages resulted in forming concave shoreline in these areas after the tsunami. The morphological recovery of this area is presented through analysis of aerial photography. In addition a new analytical solution of one-line model, which describes the evolution of shoreline of concave landform bounded by rigid boundaries, has been introduced. The recovery time of morphology is evaluated from the analytical solution of one-line model. Theoretical results indicate that coastal structures at both ends have major impact on the shoreline evolution. Moreover, the recovery time of the concave portion is highly depended on the total length of sandy coast on both sides. Good agreement between measured shoreline positions and simulated results is also obtained.