H. Takebayashi, S. Egashira, H.S. Jin† and T. Sasaki, 2007. Water Surface Elevation at the Upstream Side of a River Mouth Sandbar during Floods. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 700 – 704. Gold Coast, Australia, ISSN 0749.0208

Temporal change of water level at the upstream side of a river mouth sandbar during floods is discussed by means of a depth-integrated two dimensional numerical model based on the boundary fitted orthogonal curvilinear coordinates. The results suggest that the highest water level during floods at the upstream side of a sandbar is significantly affected well by bar height but rather by unsteadiness of water discharge. On the other hand, both bar height and unsteadiness of water discharge significantly affect the continuous time of high water level at the upstream side of the sandbar. Low height bars suppress the highest water level during floods but lengthen the continuous time of high water level. This result implies that low height sandbars do not always have an advantage for flood control under all hydraulic conditions.