Tidal engineering, explained in five diagrams

Coastal engineers generally reach for one of three tools when a stretch of coastline needs protecting: a hard barrier, a managed wetland, or something in between.

Floating breakwaters absorb wave energy before it reaches a wall, at the cost of needing regular maintenance against storm damage. Tidal gates hold back a surge entirely, but concentrate pressure on whatever structure anchors them. Managed marshland works the slowest of the three, absorbing water over hours rather than blocking it outright, and needs the most land.

Most real installations combine at least two of the three, tuned to the specific coastline's tidal range and storm frequency.