Riprap

A protective layer or facing of quarry stone, usually well graded within wide size limit, randomly placed to prevent erosion, scour, or sloughing of an embankment or bluff; also the stone so used. The quarry tone is placed in a layer at least twice the thickness of the 50 percent size, or 1.25 times the thickness of the largest size stone in the gradation.

Glossary of Terms

Nearshore Current System

The current system characterised primarily by wave action in and near the breaker zone, and which consists of four parts: the shoreward mass transport of water; longshore currents; seaward return flow, including rip currents; and the longshore movement of the expanding heads of rip currents. See also nearshore circulation.

Groyne

Narrow, roughly shore-normal structure built to reduce longshore currents, and/or to trap and retain littoral material. Most groins are of rock and extend from the backshore, well onto the foreshore and rarely even further offshore.

Shoreline Management

The development of strategic, long-term and sustainable coastal defence and land-use policy within a sediment cell.

Risk Analysis

Assessment of the total risk due to all possible environmental inputs and all possible mechanisms.

Alien Species

(Also called introduced, exotic, or non-indigenous species) - A species that has been transported by human activity, intentionally or accidentally, into a region where it does not occur naturally.

Wave Length

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

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Riprap