- A lagoon is a shallow body of water separated from a larger body of water by barrier islands or reefs.
- Commonly divided;
1.Coastal lagoons
2.Atoll lagoons
- They have also been identified as occurring on mixed-sand and gravel coastlines.
- There is an overlap between bodies of water classified as coastal lagoons.
- Bodies of water classified as estuaries.
- Lagoons are common coastal features around the world.
- water with some degree of salinity. The distinction between "lagoon" and "estuary".
Atoll lagoons
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- Formed as coral reefs.
- Grow upwards while the islands the reefs surround subside.
- Eventually the reefs remain above sea level.
- Unlike the lagoons form shore-ward of fringing reefs.
- Atoll lagoons often contain some deep (>20m) portions.
Coastal lagoons
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| Coastal lagoon Hiddensee near Stralsund, Germany. |
- Gently sloping coasts where barrier islands /reefs develop off-shore.
- The sea-level is rising relative to the land along the shore.
- Coastal lagoons are shallow.
- They are sensitive to changes in sea level.
- A relative drop in sea level may leave a lagoon largely dry.
- Coastal lagoons are young and dynamic.
- Coastal lagoons are common nearly 15% of the world's shorelines.
- Usually connected to the open ocean by inlets between barrier islands.
- The number and size of the inlets, precipitation, evaporation, and inflow of fresh water all affect the nature of the lagoon.
- Little or no inflow of fresh water.
- High evaporation rates;
Lake St. Lucia, in South Africa
- Lagoons with no connection to the open ocean and significant inflow of fresh water
Lake Worth Lagoon in Florida
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| Garabogaz-Göl lagoon in Turkmenistan |
River-mouth lagoons on mixed sand and gravel (MSG) beaches
- River-coast interface typically braided.
- River interacts with a coastal environment.
- MSG coastlines are common on the east coast of the South Island, New Zealand.
- Long referred to as 'hapua' by the Māori.
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