Study on disaster overlapping of a storm surge and a river flood

This study treats an overlapping phenomenon by a storm surge and a river flood at Osaka bay and the Yodo river, Japan. Shallow water equations are used for a horizontally 2-D storm surge model and Saint Venant equations are used for a 1-D unsteady river how model. Both models are combined at the river mouth where the discharge flux and the water level are exchanged. Longitudinal water level and velocity distribution in the Yodo river are examined through the time lag of storm surge peak and river flood peak occurrence. The overlapping flood causes the higher water level and the higher velocity in the downstream section than the storm surge or the river flood alone and the desirable measure against this is proposed.