Coastal Systems

Earth System• System-A set or assemblage of things connected, associated,

or interdependent, so as to form a complex unity; a whole composed of parts in orderly arrangement according to some scheme or plan.

• Earth System-composed of interacting physical, chemical, and biological processes that move and change materials and energy on earth. The system provides the conditions necessary for life on the planet. – Example, plants, which are part of the living system, use solar energy

to change carbon dioxide into organic carbon. Less carbon dioxide in the atmosphere helps cool the planet. Winds and ocean currents move heat from the tropics to higher latitudes, helping to warm the higher latitudes.

What is a Coastal System

• Components linked by energy and material flow

What Drives Coastal Systems

• Environmental conditions– Set of static & dynamic factors that drive and

control coastal systems– Changes in conditions cause changes on coast– Major environmental conditions

• Geology• Sediments• External forces

Geology• Width and length of shelf helps

control evolution of coasts

USGS

Geology Continued– Wide and long shelfs

allow coast to prograde or build seaward

– Also blunts wave energy, protecting coast

– Also controls promontories, bay development

• Impacts wave energy– Also controls how fast

coasts will erode• Hard or softer rock on

coasts

USGS

Sediments• Important for coastal evolution

– Large sediment supply= coastal progradation

– Size and type of sediment depends on:

• Depositional process e.g river and distance of transport

• Global location– Carbonate

sediments in warm tropical waters

– Sandy sediments in low latitudes

– Muddy sediments in humid tropical environments

Malibu Creek www.santamonicabay.org

External Forcing

• Provide energy to drive coastal processes and changes– Atmospheric –wind, climate– Marine—waves, tides, currents– Terrestrial—rivers

• Marine most important, but driven by atmosphere

Coastal System• Coastal System

– “ refers to varied and complex interactions taking place at land-ocean interface, and to constant cycling of energy and material from one component of a coastal system to another in this dynamic environment.

• Example: common component of coastal system, is beach face, waves move up and down or pound face during storm

• Small waves = low energy = growing beach• Large waves = high energy=shrinking beach face

• This simple system shows interaction of energy and material and movement of material from one component to the other

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Major Components of Coastal System

• Processes• Sediment transport• Morphology• Stratigraphy

Processes

• Hydrologic-waves, tides, currents, rivers• Atmospheric- wind• Lithologic—weathering & breakdown of rock• Biologic—Contribute sediment, breakdown

sediment• Stratigraphic-sedimentary record of coastal

change

Specific Processes

A. ocean currents - transport sediment within the coastal ocean, either parallel to shore in shallow water (longshore current) or offshore into deeper water (rip current).

piscoweb.org

More Specific Components of Coastal System

B. ocean waves – wind generated mostly. Provide energy to modify coastlineC. tides

More Specific Components of Coastal System

D. ocean floor bathymetry- impact how waves break and refract.

Photograph - Greg Moore

More Specific Components of Coastal System

E. shoreline - influences the refraction and breaking of waves, as well as the flow of coastal currents.

F. streams- transport sediment to ocean, dissolved solids (silicon, iron, and calcium), and pollution.

USGS

CSULB

More Specific Components of Coastal System

G. marine life - change ocean-water chemistry by removing ions such as calcium and gases such as oxygen and carbon dioxide from water.

NASA

H. atmospheric circulation - onshore wind carries air conditioned

I. human input - includes land-derived

pollutants enter the ocean via outfall pipes, channels, and streams, as well as airborne particles. Humans also introduce pollutants into the coastal ocean from marinas and harbors, and from offshore drill rigs.

USGS

Energy for Coastal System

• Sun

Energy for Coastal System

• Earth’s internal engine

WHOI

Energy for Coastal System

• Gravitational attraction between bodies

lcsd.gov.hk