Ridges or moulds of loose, wind blown sand (fine to medium) forming on the backshore and forming the coastal features at certain locations. Dunes are more or less vegetated. Dunes are active coastal form elements acting as a flexible sand reservoir.
Another ‘concept definition’ of sand dunes is “An accumulation of loose sand heaped up by the wind, commonly found along low-lying seashores above high-tide level, more rarely on the border of large lakes or river valleys, as well as in various desert regions, where there is abundant dry surface sand during some part of the year.” From the European Environment Agency, web site: .
Because of the importance of the wind to the mobilisation of sediment, sand dunes develop from sand grains in the size range 0.2-2.0mm.
At eroding coasts dunes are moving backwards in parallel with the erosion process. Dunes act as a kind of flexible natural protection against erosion and flooding. If the vegetation is damaged by too much traffic or grazing etc. the integrity of the dunes may be endangered.
The coastal sand dunes of Europe are one of the main categories in the Coastal Wikipedia forming one of the main coastal terestrial habitats. There is also an extensive literature in the Wikipedia .
The erosion of dunes resulting from a severe storm surge is also referred to as dune erosion.
Articles about the protection and erosion of dunes:
- Types and background of coastal erosion: article on two types of erosion, dune erosion and structural erosion.
- Dune stabilisation: article on the protection of dunes against erosion.
- Mangor, Karsten. 2004. “Shoreline Management Guidelines”. DHI Water and Environment, 294pp.