Capturing the process of wave to runup

Four types of wave to runup transition processes were examined by using a high speed video camera capable of capturing 490 frames per second. The present investigation was set out to capture the missing details reported in previous study using only 30 frames per second recording rate. Through examining the wave to runup transition processes of different incoming waves with offshore Froude number ranging from 1.08 to 1.49, it was found that the main features of the four types of transition process were consistent to those described in [1]. The non-overturning process of the upper part of the wave front occurring in the collapsing type was confirmed. The water indeed shot out from the bottom to initiate the runup process on the dry beach. However, observations in the present study also suggested that there could be an in-between transition mode existing between the plunging type and collapsing type; i.e. the upper part of the wave front may overturn onto the shot out wave toe before touching the dry beach. Further research is recommended.