Rubble-mound Structure

A mound of random-shaped and random-placed stones protected with a cover layer of selected stones or specially shaped concrete armour units. (Armour units in a primary cover layer may be placed in an orderly manner or dumped at random.)

Glossary of Terms

Wind, Offshore

A wind blowing seaward from the land in a coastal area.

Erosion

The loss of sediment, sometimes indicated by the landward retreat of a shoreline indicator such as the water line, the berm crest, or the vegetation line.

Continental Shelf

The zone bordering a continent extending from the line of permanent immersion to the depth, usually about 100 m to 200 m, where there is a marked or rather steep descent toward the great depths of the ocean.

The region of the oceanic bottom that extends outward from the shoreline, with an average slope of less than 1:100, to a line where the gradient begins to exceed 1:40 (the continental slope).

Rip Current

A strong surface current flowing seaward from the shore. It usually appears as a visible band of agitated water and is the return movement of water piled up on the shore by incoming waves and winds. With the seaward movement concentrated in a limited band its velocity is somewhat accumulated. A rip consists of three parts: the feeder currents flowing parallel to the shore inside the breakers; the neck, there the feeder currents converge and flow through the breakers in a narrow band or "rip"; and the head of rip, where the current widens and slackens outside of the breaker line. A rip current is often miscalled a rip tide.

Wave Length

The horizontal distance between similar points on two successive waves measured perpendicularly to the crest.

Scarping

The erosion of a dune or berm by wave attack during a storm or a large swell.

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Rubble-mound Structure