Coast must know Flashcards
- How is the coast a natural system?
=Inputs of energy and sediment
=Components of erosional landforms and landscapes
=Components of depositional landforms and landscapes
=Outputs of energy, sediment removal, sediment above tidal limit
What are the coastal zones?
Offshore Nearshore Foreshore Backshore Swash Zone Breaker zone Surf zone
Offshore:
Beyond the point where waves have impact on seabed
Nearshore:
Between low water mark and area where waves cease to have influence on seabed
Foreshore:
Between High water mark and Low water mark.
Backshore:
above high water mark up to landward limit of marine activity
Swash zone:
Turbulent water rushes up the beach as the swash
Breaker zone:
Waves approaching begin to break
Surf Zone
between waves breaking and moving up the beach as swash
What are the sources of energy?
Waves Winds Tides Wave refraction Currents
What are the 2 types of wave?
Constructive
Destructive
What are the characteristics of constructive waves?
Low height, Frequency (6-8/min), energy. Swash more powerful than backwash, Beach is built up Gentle beaches
What are the characteristics of destructive waves?
High heights,
Frequency (10/14/min), energy. Backwash stronger than swash
Sediment removed
Steeper beaches
What does the energy of wind depend on?
strength
duration
fetch
What are tides?
What are the 2 types?
Gravitational pull of the moon and to a lesser extent the sun,
Creating spring tides (every 14 days)
When aligned and neap (every 14 days) at right angles.
High (and low) tides occur 12 hours and 25 mins apart.
What do tides vary due to?
Morphology of sea bed, Proximity of land masses Coriolis force
What is Wave refraction?
Energy of wave becomes concentrated on headlands and dissipated at bays
Since waves in shallow water slow down due to friction with sea bed.
What are the 3 differnt types of current?
Longshore currents -
Rip currents -
Upwelling
What are Longshore currents?
The process of Longshore drift
What are rip currents?
move away from the coastline at for example a headland
What is upwelling?
cold water makes it’s way to the surface
What is a sediment cell?
How many are there is England and Wales?
Sediment cell is a stretch of coastline, usually bordered by two headlands, where the movement of sediment is largely contained.
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What happens within a sediment cell?
Within the cell there are inputs (sources), transfers and stores (sinks).
What is a sediment budget?
What can upset this?
The sediment budget is the amount of sediment that is available and tries to be in dynamic equilibrium.
Can be upset by a storm or sudden increase in discharge or by human activity e.g. groynes
What are the geomorphological processes?
Processes involved in the change of landforms Erosion Transportation Deposition Weathering
What are the coastal processes of erosion?
Wave quarrying - Attrition - Solution - Hydraulic action - Abrasion -
What is Wave quarrying?
Cavitation which traps air causing huge pressure, which is released when wave withdraws
What is attrition?
material being carried by the sea hit against each other becoming smaller, rounder and smoother
What is Solution?
Solution - rocks, normally limestone or other rocks containing carbon, are dissolved, though this is normally by rainfall and is therefore not technically erosion but….
What is Hydraulic Action?
Hydraulic action - sheer force of the water puts pressure on the rocks and forces them apart
What is Abrasion?
Abrasion - material is used by the waves e.g. shingle which is thrown at the cliff
What are the coastal processes of transportation?
Saltation - Traction - Solution - Suspension - Longshore drift -
Saltation
Saltation - sediment bounces along the bed of the sea and dislodges other particles
Traction
Traction - bedload rolls along the sea bed
Solution
Solution - minerals are dissolved and are carried in the water
Suspension
Suspension - particles are carried along in the water
Longshore Drift
Longshore drift - swash comes in at an angle due to prevailing wind direction, backwash straight back down due to gravity, moves material in a zig zag along the coastline
What are the coastal processes of deposition?
Where marine energy is lost
Aeolin - carried/desposited by the wind
Where is marine energy lost?
The wave slows down after breaking
Where accumulation is quicker than removal
Where the coastline changes direction
Just before backwash