dune

(redirected from Sand dune system)
Also found in: Dictionary, Thesaurus.

dune,

mound or ridge of wind-blown sand formed in arid regions and along coasts. Dunes are common in most of the great deserts of the world. Often a dune begins to form because material is deposited by the wind as it encounters a bush, a rock, or other obstacle to impede its flow. Dunes that are not stabilized by vegetation have a tendency to migrate, driven by the prevailing wind. These free-moving dunes are of two main kinds, transverse and longitudinal, and the characteristic form is maintained in migration. Transverse dunes usually form where wind blows quite constantly from one direction across expanses of loose sand; the windward slope is typically gentle, and the lee side, where the sand blown over the crest seeks its natural angle of repose, is steep. Such dune ridges have a tendency, especially with increasing distance from the source of sand, to break up into individual small hills. One of the commonest forms of these hills is the symmetrical, crescent-shaped, transverse dune called a barkhan; examples can be found at Pismo Beach, Calif., and near Arequipa, Peru. Longitudinal dunes are ridges, with about the same slope on both sides, elongated in the direction of the prevailing wind. They are especially well developed in the African deserts and are also seen in Arizona and in the Imperial Valley, Calif. Coastal blowout dunes, which are approximately U-shaped with their open ends upwind, form along shores where vegetation cover is locally broken. Examples are the dunes along the southern and eastern shores of Lake Michigan. Dunes reaching a height of more than 500 ft (150 m) exist in the Great Sand Dunes National Park and Preserve, Colo.; gleaming white dunes of gypsum sand are formed in White Sands National Monument, N.Mex. Sand dunes may cause destruction as they migrate; in France on the coast of the Bay of Biscay they destroyed villages and farmland. In some areas of Europe and the United States this danger has been checked by planting vegetation and by erecting barriers. One value of dunes is their absorption of rain, which helps to raise the level of the water table and thus produces oases in some areas and provides accessible sources of water through rather shallow wells.

dune

[dün]
(geology)
A mound or ridge of unconsolidated granular material, usually of sand size and of durable composition (such as quartz), capable of movement by transfer of individual grains entrained by a moving fluid.

dune

a mound or ridge of drifted sand, occurring on the sea coast and in deserts
References in periodicals archive ?
Although both species tested here performed well on the adjacent sand dune system, their slightly different responses to some of these constraints may be enough to compromise the success of a restoration trial.
These diet preferences probably reflect that in sand dune systems, homopterans, lepidopterans and coleopterans are uncommon among the perennial plants during drought periods, but these kinds of arthropods are particularly abundant in shaded areas with grass after the rains and when water ponds begin to dry up.
"Sand dune systems are good at responding tochange.They roll backand roll forward so they will probably respond a lot better to rising sea level."
WALES' IMPORTANT SAND DUNE SYSTEMS KENFIG DUNES, BRIDGEND: Some of the dunes cover the site of an ancient town and castle.
Trystan Pritchard is public relations officer for the Countryside Council for Wales More natural coastline will be created: The Newborough Warren sand dune system is the largest in Wales covering 1300 hectares.
We have incorporated the sand dune systems into the design of Al Saad to enable the community to feel connected to the local environment and enjoy the scenic views created."
"We have therefore incorporated the sand dune systems into the design of Al Saad to help the community feel connected to the local environment and enjoy the scenic views the dunes offer," said Abdulla Al Sahi, acting executive director for planning and infrastructure at the UPC.
The Golf Environment Organisation, which vets courses and is backed by the European Tour, complained of the course's "considerable negative impact on what was one of the UK's most valuable mobile sand dune systems".
However, early successional sand dune systems have very low nutrient availability (2-5 ppm, unpub, data; also see Lichter, 1998) and native grasses are often more competitive than Centaurea in such environments (Herron et al., 2001).
BULLDOZERS have moved on to Kenfig National Nature Reserve in an effort to remodel its sand dune systems.
of Western Ontario, Canada) offers an introduction to the formation, dynamics, and perpetuation of coastal sand dune systems. He describes interactions between living organisms and the physical processes of geomorphology, with an emphasis on conservation and management, in response to the increasingly endangered status of dunes.