Coasts As Systems Flashcards
Give reasons as to why a systems approach may be used to study the costal zone
Explain and predict variation
As a model to aid understanding
Enables mitigation of the variation
Give the four sources of energy in the costal system
Wind
Waves
Tides
Currents
What is wind? What three things to do they cause?
Wind is movement of air from high pressure to low pressure
Acts as an agent of erosion (abrasion) and an agent of transport, cause waves by applying energy over the water
How are waves formed? Describe how they break as well
Wind causes friction on the surface of the water, leads to a circular motion, when they approach the shoreline the waves face frictional forces from the sea bed, causes the orbit to differ until the wave crest collapses
Differenatiate between swash and backwash
Swash is water flowing up the beach
Backwash is the force of gravity pulling water backdown the beach
Describe a constructive wave
Low frequency
Long wavelength
Low height
Swash dominates so more deposition occurs than erosion, giving a gentle beach gradient
Describe a destructive wave
High frequency
Short wavelength
Impeded swash due to previous backwash
More erosion than deposition giving a steep beach
Give an example of negative feedback in the costal system
Constructive waves build up the beach, which becomes steeper, which favours destructive waves leading to greater erosion.
Describe tides,
What is the tidal range?
When does a spring tide occur?
Rises and falls in the level of the ocean due to the gravitational force of predominantly the moon but also the sun. A compensatory buldge occurs on the opposite side of planet, in between is low tide
Tidal range is between low and high tide
Spring tide occurs when sun and moon are in allignment
Briefly describe three types of currents
Currents are permanent flows of water in a paticular direction
1) longshore current - approach at angle but move away perpendicular
2) rip currents - localised underwater currents, plunging waves cause temporary water build ups, backwash is impeded so is pushed underwater
3) upwelling - cold water moves upwards as it is less dense
Describe a high energy coastline
Large powerful waves
Strong winds,long fetches
Rocky landforms
Often facing the prevailing wind
Describe low energy coastlines
Gently breaking waves Lower wind speeds Short fetches Gentle profile Depositional landforms
Give sources of sediment in the costal system
Rivers
Sea level rise
Eroded sediment
Waves tides and current carrying sediment
What is the sediment budget?
The balance between inputs and outputs, inputs>outputs is positive and vice versa
Describe sediement cells
How many in UK?
Theoretical closed systems
Processes within them have no effect on other sediment cells
Management often occurs on a sediment cell basis
11 in the UK e.g. Holderness coast
