Coastal zone characteristics

This one should be relatively short - with links to more specific entries.

Different coastal types:

Sandy beaches

sandy coast

Sand is a very common marine sediment and is transported along the shoreline by littoral transport. Sand transport (littoral transport or littoral drift) is driven by the breaking waves and the longshore currents in the wave breaking zone. The appearance of natural Sandy beaches is determined by hydrographic conditions and geology. Any interference will cause a reaction in the form of a shoreline response. Therefore, understanding of physical processes is important and the development of suitable solutions required, supported by numerical modelling if needed.

Muddy coasts

mangrove coast

Muddy coasts are only found in environments that are fairly calm with respect to wave conditions; or there is abundant supply of fine sediments. They are normally vegetated e.g. mangroves fronted by very flat slopes or tidal flats and a muddy coast with mangrove vegetation is characterized by a muddy shoreface, sometimes in the form of muddy tidal flats, and the lack of a sandy shore. Mud has special properties.

Rocky coasts

Rocky coasts:

• are continuously cut back by the sea and are characterised by erosional features
• have a slow rate of morphological change
• experience the main erosional processes of: mechanical wave erosion, abrasion and hydraulic action; weathering - physical, salt, chemical and water-layer levelling; bio-erosion - biochecmial and biophysical; and mass movements by rock falls and toppling, slides and flows.

Barrier coasts

barrier coast

• Barrier islands (see diagram) are parallel to the shore, separated from mainland by a lagoon
• in a profile with a more gentle slope than the equilibrium profile, sediments will be moved onshore, as waves on the shoreface will primarily transport sand towards shore attempting to build up equilibrium profile. Waves lose their energy over the gentle shoreface and deposition occurs some distance from shoreline --> eventually develops into a barrier island (cross-shore transport)
• transport of sand by longshore transport will add to barrier formation, a combination of sand spit and barrier island processes, normally occurring under type 1 and 2 conditions

See also

Classification of Coastlines

References

(Caitlin 09:31, 18 January 2007 (Romance Standard Time))