7. 13新潟・福島豪雨水害時の五十嵐川洪水の再現とその特性

抄録

On July 13, 2004, a heavy rainfall hit the Niigata area, resulting levee breach in the river Ikarashi. The inundation claimed 9 victims and caused huge property damage. The present work conducted analysis on peak discharge and water level variation at the place where the levee was breached. It also carried out flood inundation simulation in order to gain a better understanding of the consequences of the levee failure. It is found that the peak discharge on July 13, 2004 exceeded the full capacity of the river Ikarashi by approximately 20%. As a result, overflow with a depth of 20~30cm occurred which was probably the main cause of the dike break. Besides, outflow hydrograph from the breach was estimated for performing inundation simulation. Flood inundation simulation shows that the water spread out through the Sanjo City generally in two directions, and maximum inundation depth was above 2m.