Backfilling of Sandy Coast Breaching After the 2011 Tsunami

Abstract

Breaching of sandy coast was commonly observed on Yamamoto Coast, southern Miyagi Prefecture during the 2011 tsunami. That made the shoreline having concave shape after the tsunami. Concave shoreline is bounded by two headlands. The recovery of concave shoreline is discussed through the analysis of satellite images. The relationship between dimensionless elapsed time with dimensionless recovery of shoreline at the central line of concave portion, and dimensionless of area of backfilling in the concave portion are studied based on analytical solutions of the one-line model. For those two relationships, results obtained for case with rigid boundaries is asymptotic when the ratio between length of the bounded coast and width of concave portion is getting larger. Good agreement between measured data and theoretical results can be obtained.