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Glossary of Terms

Gabion

Steel wire-mesh basket to hold stones or crushed rock to protect a bank or bottom from erosion. Structures composed of masses of rocks, rubble or masonry held tightly together usually by wire mesh so as to form blocks or walls. Sometimes used (although not recommended) on heavy erosion coastal areas to retard wave action.

Photogrammetry

The science of deducing the physical dimensions of objects from measurements on images (usually photographs) of the objects.

Nutrients

Substances that are essential for the growth of marine organisms that perform primary production (algae, bacteria, and plants). Excess nutrients, especially nitrogen and phosphorus, can be major pollutants.

Sediment Transport

The main agencies by which sedimentary materials are moved are: gravity (gravity transport); running water (rivers and streams); ice (glaciers); wind; the sea (currents and longshore drift). Running water and wind are the most widespread transporting agents. In both cases, three mechanisms operate, although the particle size of the transported material involved is very different, owing to the differences in density and viscosity of air and water. The three processes are: rolling or traction, in which the particle moves along the bed but is too heavy to be lifted from it; saltation; and suspension, in which particles remain permanently above the bed, sustained there by the turbulent flow of the air or water.

Shoreline

The intersection of a specified plane of water with the shore or beach (e.g. the high water shoreline would be the intersection of the plane of mean high water with the shore or beach). The line delineating the shoreline on nautical charts and surveys approximates the mean high water line.

Micro-tidal

Tidal range less than 2m.

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