24. What is the wall designed to do?
The defence is designed to reduce green water slopping over and running down to town. Typically waves hit the sea wall and is forced upwards. The spray goes high and although spectacular, has little volume that contributes to flooding. The wave itself is known as green water, and contains most of the volume of the floodwater. This goes up and falls onto the esplanade. If enough water makes its way onto the esplanade at one time, it will slop over the splash defence as shown by the video at the end of this answer. The defence needs raising to reduce this slop, or secondary waves caused by waves crashing on a flooded esplanade.
This is best shown on this video, which shows water slopping over the splash wall from 1m30 onwards.