Morphology Changes on Sendai Coast after the 2011 Great East-Japan Earthquake Tsunami

Abstract

Characteristics of the beach recovery process on Sendai Coast after the 2011 Great East Japan Earthquake Tsunami are discussed through the analysis of shoreline changes measured from aerial photographs which have been taken every 1 or 2 months. Coastal structures located near shoreline such as detached breakwaters, which reduce long-shore sand transport, have a significant effect on the recovery process. An embankment of 15m height located near the Nanakita River mouth has been eroded intermittently by high waves to be a large source of sand. The retreat of the shoreline near the Nanakita River mouth has been reduced by 12 cm/day on average, while the change rate near the Natori River mouth is 7 cm/day. The beach morphology on Sendai Coast is not in an equilibrium state even after 2 years from the tsunami.