1. Department of Civil Engineering, Kobe University , Kobe City, Japan
2. Department of Civil and Environmental Engineering, Kitami Institute of Technology , Hokkaido 090-8507, Japan
3. Faculty of Hydrology and Water Resources, Water Resources University , Hanoi, Vietnam
4. Department of Civil and Environmental Engineering, Tokyo Metropolitan University , Tokyo 192-0397, Japan
5. Department of Civil and Environmental Engineering, Kitami Institute of Technology , Kitami City, Japan