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Transcript of Coastal Studies
Beaches occupy half of the Australian open coast. There are 10 685 beach systems in Australia, and they are a vital and iconic part of the coastal landscape and ecosystem. Most Australian beaches are quite short and average 1.4 kilometers in length, although some extend for several kilometers. For the most part they are bounded by rocky headlands or reefs and are backed, and, in some cases, flanked by some form of sand dune.
Different types of Coastlines:
Northern/Tropical - tide dominated beaches, limited dunes, numerous rivers, deltas and estuaries, mangroves, tropical species of plants and coral reefs.
Southern/Temperate - wave dominated beaches, extensive dunes, rock shores, small rivers, limited estuaries, temperate species and sea grasses.
Sandy coastlines and Rocky Coast lines
We live near both rocky and sandy coastlines. We also have instances of both northern tropical and southern temperate coastlines.
How does the coast line form
Coasts are a product of the interaction of the Earth’s four great “spheres”:
• the lithosphere
• the hydrosphere
• the atmosphere
• the biosphere.
These four subsystems, or spheres, are the reason the coast is dynamic. It is along the coast that all four spheres continuously interact
What is Beach Sand Deposition?
Beaches form as a result of waves depositing sediment (usually sand, but occasionally pebbles and boulders) at the shore. They extend from the wave base, across the near-shore and surf zone, to the swash zone where waves run up the beach.
In simple terms,
No Waves No Beach!
What are Coastal Dunes?
Coastal sand dunes back most Australian beaches. Sand dunes form when strong winds blow fine to medium sized sand particles inland from the beach. The transported sand will settle when the wind drops or it becomes trapped by vegetation.
Waves transport sand onshore to build beaches. When storm waves erode a beach, the sand is quickly carried by large rips and deposited out in the surf and near-shore zones. The sand is returned to the beach over a period of months to years by wave action in moderate weather conditions. This is known as the cycle of erosion and accretion.
Humans have modified the Australian coastline, resulting in alterations to coastal sedimentary systems. These changes include
• constructing housing estates in former wetlands
• altering river discharge and river-mouth shape and currents with training walls
• installing sea walls and groynes on popular beaches to control erosion
• dredging estuaries for navigation and urban expansion.