Why do sea levels change globally???

Beaches are easily recognizable secondary coasts Beaches are easily recognizable secondary coasts. Form from the deposition of eroded sediment in “quiet” areas.

Movement of eroded sediment, as well as sand along an established beach, is caused by 2 main features – longshore current and longshore drift.

Rip Currents are narrow, fast currents moving offshore and are produced by the backwash from the longshore current Can be dangerous to swimmers - swim across (parallel to shore) or ride them out until they slow just offshore MSCI 210 – Chapter 9 – Coasts, Estuaries, and Environmental Issues

Barrier Islands Long, offshore deposits of land which are parallel to the coast Often provide a barrier to storm waves Origin is complex - many were formed during the rise in sea level sea level following the last ice age (18,000 years ago) Nearly continuous along the US Atlantic coast and Gulf of Mexico

Beach Profile Animation Tobay Beach at Jones Beach Island, NY http://people.hofstra.edu/faculty/J_B_Bennington/research/beaches.html

Fringing Reef Figure 11.23 A small section of the Great Barrier Reef, Queensland, Australia. This coast has been extensively modified by biological activity.

Estuaries Tectonic Coastal Plain Fjord Bar-built Estuary - a partially enclosed body of coastal water where salty ocean water is mixed by water from land runoff and, typically, rivers. Are usually associated with river mouths May support important commercial and recreational fisheries Many major seaports are estuaries - lots of ship traffic Origin of Estuaries Most were created by sea level rise over the past 18,000 years (since the last ice age) During this time, sea level has risen about 180 meters (400 feet) Four Major Classes of Estuaries Tectonic San Francisco Bay Coastal Plain Chesapeake Bay Galveston Bay Fjord Strait of Juan de Fuca Washington Bar-built Laguna Madre, Texas

=coastal plain

Estuarine Circulation In areas where river input exceeds evaporation, freshwater water flows out of the estuary at the surface Saltier water flows into the estuary along the bottom Mixing patterns vary with season, tides, freshwater inflow, and wind Residual flow – currents not associated with tidal ebb and flood

Estuaries Are vital natural ecosystems - health is essential for world’s fisheries Commercial and Recreational Importance Human activities have had a major impact on estuaries Waste inputs, habitat destruction, chemical pollution, and declines in overall water quality peaked in the 1970’s The Clean Water Act and improvements in waste treatment are big steps toward cleaning up estuaries Population will continue to increase in the coastal zone and estuaries will experience increasing use Eutrophication is a general term that describes an overall decline in water quality due to increased inputs of nutrients – including animal waste and fertilizers. Many estuaries in the US are under increasing stress imposed by human activities in the coastal zone. Habitat destruction is major cause of concern but the increased sources of pollutants that come along with increased development are also major stressors. Concept of Sustainable Coastal Development Inputs can come from Point or Non-Point Sources Non-point sources are the most difficult to control and will be the major problem over the next few decades

Coastal Development National Flood Insurance Program For $1000, you can purchase a $200,000 insurance policy to protect against flood damage Policy would cost $18,000 if purchased from private insurance company Affordable insurance encouraged overdevelopment of the coastal zone 1982 Coastal Barrier Rezoning Act Excludes new construction in undeveloped coastal areas from federal insurance assistance Miami Beach Undeveloped salt marshes were critical in protecting many areas during Katrina.