EVOLUTION OF NOBIRU COAST AFTER THE 2011 TSUNAMI IMPACT

Abstract

 Nobiru Coast, which is 2.8 km long coast located in Miyagi Prefecture, Japan, is a well-known coast because of high sediment deposition rate. The predominant littoral drift of this coast is from east to west. The sediment deposit at the western end causes significant effect on the aquaculture in Matsushima Bay which is located on the right of Miyato Island, due to closure of a channel connecting open sea and Matsushima Bay. Due to the impacts of the 2011 tsunami, the coastal areas were seriously damaged and the channel was opened again. According to the shoreline analysis on Nobiru Coast at decadal to centennial scales including the 2011 tsunami impact using aerial and satellites images, the longshore sediment transport rate on Nobiru coast from 1964 to 2006 reduced about 60% compared to the one in the previous period. However, that increasing rate does not change much in the period after the tsunami although severe damages could be observed. The present amount of sediment corresponds to that during early 1980s. Therefore, it can be roughly estimated that the blockage of the Katsugigaura Channel due to the sediment deposition on the west end of the coast will take place again in the future around 2040s.