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

Natural sandy beaches:

• Their appearance is determined by hydrographic conditions and geology
• Any interference will cause a reaction in the form of a shoreline response

Therefore:

1. Understanding of physical processes is important
2. 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
• are normally vegetated e.g. mangroves fronted by very flat slopes or tidal flats
• 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
• cohesive sediments have special properties

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