Mangrove forests grow in the intertidal zone between land and sea, anchored by dense tangles of prop and pneumatophore roots. That root mesh acts as natural coastal armour: as a storm-surge wave pushes through the belt, drag against the stems and roots removes energy from the water, so the wave that finally reaches dry land is smaller than the one that arrived offshore.
Field and modelling studies (e.g. McIvor et al. 2012) estimate that 100 metres of healthy mangrove can reduce incoming wave height by 13–66%, and coastal communities behind intact mangrove belts consistently report far less storm damage than those behind cleared shorelines.
A storm-surge wave rolls in from open water and pushes through a belt of mangrove trees; the roots drag against the water and dissipate its energy, so the wave — and the flooding it causes — is far smaller by the time it reaches dry land.
Wave height decays exponentially as it crosses a mangrove belt, with the decay rate set by root density and maturity. Less energy surviving the belt means a shorter inland flood reach.
Adjust mangrove density, root maturity, and storm surge intensity, then trigger a surge and watch the crest shrink as it crosses the belt. Toggle bare shoreline to compare against unprotected coast.
Research summarised by McIvor et al. (2012) found that 100 metres of healthy mangrove forest can cut incoming wave height by 13–66%, making mangroves one of the most cost-effective natural flood defences.