Coastal Foredunes

Landward of beaches, there is often a narrow belt of dunes guarding the coastline. These coastal foredunes are irregularly shaped hills and depressions.

They are normally covered by beach grass with a few other species of plants that can survive the severe environment.

This plant cover traps sand moving landward from the adjacent beach.

As a result, the foredune ridge builds upward, becoming a barrier several meters above high-tide level.

Foredunes form a protective barrier for tidal lands on the landward side of a beach ridge or barrier island.

In a severe storm, the swash of storm waves cuts away the upper part of the beach.

Although the foredune barrier may then be attacked by wave action and partly cut away, it will not usually yield. Between storms, the beach is rebuilt, and, in due time, wind action restores the dune ridge, if plants are maintained.

But if the plant cover of the dune ridge is trampled and reduced by traffic—from vehicles or by foot— deflation will rapidly create a blowout.

The new cavity becomes a trench across the dune ridge.

When storms bring high water levels and intense wave action, swash is funneled through the gap and spreads out on the tidal marsh or tidal lagoon behind the ridge.

Sand swept through the gap is spread over the tidal deposits.

If eroded, the gap can become a new tidal inlet for ocean water to reach the bay beyond the beach.

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