5/17/20111Chapter 12 Coasts, Beaches, and Estuaries12.1 Major Zones• Coastal area: land edge that borders the sea– Width varies • Geography• Climate• Vegetation• Social customs and culture• Shore: outer limit of wave action on the bottom to the limit of the waves’direct influence on landthe waves direct influence on land• Beach: accumulation of sand or gravel that occupies part of the shoreCO 12 Fig. 12.1aFig. 12.1c Fig. 12.2b5/17/20112Fig. 12.2c Fig. 12.312.2 Types of Coasts• Primary coasts– Effect of ice ages– Effect of sediment carried by rivers– Effect of wind– Effect of volcanic activity– Effect of tectonic activity• Secondary coasts– Erosion due to wave activityBarrier islands–Barrier islands– Coral atolls and reef coasts– Mangrove swamps and salt marshesFig. 12.4Fig. 12.5 Fig. 12.75/17/2011312.2 Types of Coasts• Primary coasts– Effect of ice ages– Effect of sediment carried by rivers– Effect of wind– Effect of volcanic activity– Effect of tectonic activity• Secondary coasts– Erosion due to wave activityBarrier islands–Barrier islands– Stabilization due to plant growth – Coral atolls and reef coasts– Mangrove swamps and salt marshesFig. 12.9Fig. 12.10 Fig. 12.13Barrier Island •Barrier chains are aligned parallel to the coastNOTES•Barrier chains are aligned parallel to the coast•Most have formed in a regime of slow eustatic sea-level rise•They are separated from the mainland by shallow lagoons, marshes, and/or tidal flats•Tidal inlets separate individual barriers along a chain•They are composed mainly of sand•They formed during periods of sand abundanceBluff Coastlines5/17/20114Coastlines are influenced by hydrodynamic forces (waves, tides (currents), rivers, changing sea levels)Longshore Transport of SandBarrier and Spit FormationBeach Dynamics:Summer: gentler waves move sand shorewardWinter: large storm waves remove sand to offshore bars5/17/20115•Barrier Island (coastline) changes can be gradual.•Barrier island rollover at Assateague IslandDelta CoastlinesNew York City Panel on Climate Change, 20091 Based on 16 GCMs (7 GCMs for sea level rise) and 3 emissions scenarios. Baseline is 1971-2000 for temperature and precipitation and 2000-2004 for sea level rise. Data from National Weather Service (NWS) and National Oceanic and Atmospheric Administration (NOAA). STET and sea level data is from the Battery at the southern tip of Manhattan (the only location in NYC for which comprehensive historic sea level rise data are available).2 Central range = middle 67% of values from model-based probabilities; temperatures ranges are rounded to the nearest half-degree, precipitation to the nearest 5%, and sea level rise to the nearest inch.3 The model-based sea level rise projections may represent the range of possible outcomes less completely than the temperature and precipitation projections. See page 18 for more information.4 “Rapid ice-melt scenario” is based on acceleration of recent rates of ice melt in the Greenland and West Antarctic Ice sheets and paleoclimate studies.Tidal Inlet FormationBarrier Island BreachingShinnecock Inlet, 19385/17/201169 ft12 ft15 ftCoastlines are influenced by vegetation•Coastal wetlands occupy 27 million acres. •Four times more productive than the most productive farmland.•80 percent of commercial fish are dependent on food chainsCoastal Wetland: vegetated intertidal environmentare dependent on food chains which can be traced back to these coastal environments Global Distribution of Coastal WetlandsMangroves can not survive in freezing temperaturesSharp Transition Between ZonesMangroves Were regarded as muddy, mosquito and crocodile infested swamps. In the past their removal was seen as a sign of progress. Coral Reefs5/17/20117Estuaries: where the ocean meets fresh waterTypes:Drowned River MouthsFjordsBar-BuiltTectonicoEstuary characteristics are influenced by water density and flowoEstuaries support complex marine communitiesShoreline Erosion: Methods for maintaining coastline stabilityTidal Inlet FormationBarrier Island BreachingPikes Inlet,