東日本大震災津波後の河口砂州河道内侵入現象

Abstract

The Great East Japan Tsunami of 2011 caused severe morphology changes along the affected shoreline, including sand formation in front of the river mouth. This study investigates the recovery process of this sand formation at several rivers. Sand spit intrusion into the rivers occurs during the recovery process. The river mouth width and the intrusion distance show similar relation and trends, which was also observed in sand intrusion into the river due to jetty construction. A more detail analysis show that the river mouth was severely eroded by the tsunami. The water depth in the river mouths was significantly deeper after the tsunami. Thus, the location of the depth of closure was moved into the rivers, which lead to the sand intrusion. This agrees well with laboratory experiments from previous study.