Flashcards in Coastal Landscape systems Deck (29):
What is a system?
interrelated components (stores) and processes that connect to form a working unit.
What do the 3 types of energy enable?
Enable geomorphic processes to shape the land.
Where is material from?
sediment on beaches, the nearshore zone, estuaries
What are the inputs into the system?
Energy (kinetic from wind/waves, thermal from sun) and material (marine deposition, weathering and mass movement). Potential from position of material on slopes
What are the outputs of the system?
Material transferred to other systems, marine/wind erosion and evaporation.
What are throughputs in a system?
Processes, stores (beach/nearshore sed accumulation) and flows (transfers, e.g. LSD).
What is equilibrium?
When the systems inputs/outputs are equal.
What is negative feedback?
it is dynamic equilibrium, when e is disturbed the system self regulates to produce its own response.
What is a sediment cell?
Stretch of coastline and its nearshore area, within which the movement of coarse sed is largely self contained. But wind direction change/tidal currents means its not a closed system.
Describe characteristics of a constructive wave:
low height/freq. and long wavelength. Breaks as spilling, strong swash up sloping beach. Swash energy exceeds backwash energy (swash uninterrupted).
Describe characteristics of a destructive wave:
Shorter wavelengths and higher. Break as plunging, so little forward transfer of energy up steep beach. Backwash exceeds swash (swash slowed by friction of previous backwash due to short wavelength).
How do winds influence a coastal system?
Frictional drag of wind over ocean surfaces generates wave energy (longer fetch/higher speed means more energy). Energy carries out erosion, transportation and deposition, all Aeolian processes.
What energy does a wave possess?
Potential (position above wave trough) and Kinetic (motion of water in waves). Relationship between wave height and energy is non-linear.
What are the 4 parts of a wave?
Crest (highest), Trough (lowest), Height (vertical distance between crest/trough), Length (horizontal distance).
What are waves affected by?
Gradient of sea floor, irregularity of coast, wind (?)
What is the difference between a swell and a storm wave?
Swell forms over open oceans, generated from a long distance, wave period of 20secs+, Storm waves are locally generated, higher with a shorter period/length.
Describe a breaking wave:
In shallow water, the wave touches the seafloor and friction changes the speed/direction/shape of it.
What are the three types of breaking waves?
Spilling (steep waves on gently sloping beaches, water spills forward), Plunging (moderately steep waves break onto steep beaches, water plunges vertically as crest curls over) and Surging (low angle on steep beaches, wave slides forward, may not actually break).
What is the relationship between beach gradient and wave type?
High energy waves (winter) remove material from top of beach to offshore zone (reduced gradient), low energy (Summer) build up beach face, steeper gradient.
What causes Longshore drift?
Once deposited, sed moved along the shoreline, it occurs when waves approach the coast at an angle (due to direction of dominant wind).
How is sediment moved in LSD?
Waves break, swash carry particles diagonally up beach (wind direction), backwash moves it perpendicularly back down the beach. Sed also has attrition, tend to be smaller with increasing distance along the beach.
Why does deposition take place?
Loss of energy/decreased velocity; when rate of sed accumulation exceeds removal, waves slow after breaking, during backwash when water percolates and in low energy environments (sheltered from wind/waves).
Why do tidal ranges vary?
Enclosed seas such as the Med have a low range, so wave action is restricted to a narrow area of land where the coast is funnelled.
What is lithology?
the physical/chemical composition of rocks.
What is a concordant coastline?
Rock outcrops that are uniform/parallel to the coast, produce straight coastlines.
What is a discordant coastline?
Rocks lie at right angles to the coast create a planform that is 'uneven', resistant rocks make headlands. weaker make bays.
How are ocean currents created?
Earths rotation and movement of winds across a water surface.
What is terrestrial sediment?
Rivers as sources of sed input into the sed budget, in some locations 80% of coastal sed is from rivers.