The Coastal System

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The Coastal System
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The Study of Coasts

• Coasts can be studied in several different ways
  dependent upon their classification
• Erosional or depositional
• Sediment type (clastic shingle and sand or
  muddy)
• Submergent or emergent
• Tectonic setting
• Process-based wave dominated, tide dominated and
  wind dominated - the agents of erosion

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Wave Dominated Tide Dominated Wind Dominated
Shore Platforms Mudflats Sand
Dunes Cliffs Sandflats Beaches Salt
Marshes Spits, Tombolos Mangroves Deltas Delta
s

• Questions Answers
• Cause and Effect
• Knowledge Understanding

Energy
High
Low
(French, 1997)
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Coastal Processes
Weathering, Erosion, Deposition
Coastal Form
Dynamic over Space Time
Equilibrium
Wind, Waves, Tide, Currents
Sediment Movement
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The Coastal System
ENERGY
WIND
WAVES
TIDES
GEOLOGICAL STRUCTURE
MATERIALS
Dominant
Less Dominant
Terrestrial
Marine
Coarser
Finer
Cliffs and Shore Platforms
Mudflats
Coral Reefs
Beaches
Sand Dunes
(Hansom, 1988)
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The Coastal System

• Coastal Systems
• coastal systems vary primarily in response to
  wave intensity and tidal currents
• breaking waves (and resultant currents) provide
  most of the systemic energy
• several additional factors also influence coastal
  processes and landforms
• original geology of the coastline
• relative 'erodibility' of regional bedrock
• sea level variations (global and local tectonic
  or glacio-eustatic changes)
• coastal systems typically characterized as
  erosional or depositional
• erosional or depositional nature of any coastline
  varies with the systemic energy

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Weathering Erosion
What is? Weathering Breakdown of rock (Geology)
to form sediment in situ Weathering is a set of
physical, chemical and biological processes that
alter the physical and chemical state of rocks
and soil at or near the earth's surface. Rock and
soil is altered physically by disintegrating and
chemically by decomposing. Nearly all weathering
involves water, mostly directly frost
shattering, wetting and drying, salt weathering,
and all chemical weathering is in solution. That
is, weathering is climatically driven and thus
the term weathering. Because weather and climate
occur at the earth's surface, the intensity of
weathering decreases with depth and most of it
occur within less than a metre of the surface of
soil and rock. ErosionTransport of weathered
material from one location to another...The
wearing away of land or the removal of beach
and/or dune sediments by wave action, tidal
currents, wave currents, drainage, or wind.
Erosion includes, but is not limited to,
horizontal recession and scour and can be induced
or aggravated by human activities.
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Erosional Depositional Coastal Landforms