Wave set-up height in river entrances due to extreme waves

Information of maximum water level, including wave set-up height, at a river entrance is very important in terms of river mouth morphology change, navigation transportation, and saline water intrusion into a river or lagoon. The wave set-up at a river entrance is the height of Mean Water Level above Still Water Level and usually occurs during an extreme event such as storm or hurricane. In this study, full field data sets from six river mouths located in Japan are compiled and analyzed. The results show that the wave set-up height is not only depending on wave breaking at the entrance but also affected by the river discharge and river mouth morphology. The wave set-up height attains from 2 to 13 percent of offshore wave height for the cases of average water depth at entrance ranging from 1.1 m to 6.5 m. The final result is obtained as a technical diagram for predicting the wave set-up height at the river entrance.