東日本大震災における津波の河川遡上による堤防越流と被害状況の把握

抄録

The tsunami caused by the Great Japan Earthquake on 11 March 2011, broke most of the sea embankment and coastal vegetation belt and caused catastrophic damage to people and buildings in the Tohoku and Kanto regions of Japan. Field surveys were conducted to elucidate the damage to river embankments and their hinterlands (residential area) by tsunami propagation in river channels and overtopping of embankments. Ten rivers were selected for the field investigation. In the hinterlands where overtopping occurred, the tsunami came from two directions, coast and river. It is necessary to identify locations of river embankments that can be easily overtopped by a tsunami in different tsunami conditions, river morphology and inland embankment of roads or trains. Tsunami inundation patterns were classified by the river capacity and whether a river or sea embankment was breached or not. This will provide useful information for making new hazard maps and planning new cities. Numerical simulation in Abukumagawa River shows the clear relationship between the scoured area and the tsunami overtopping time.