Essential Notes Flashcards
Is the coast an open or closed system?
Open
What are different sections of the coast known as?
Sediment cells
What are sediment cells bordered by?
Prominent headlands
What is the movement of sediment like within sediment cells?
The movement of sediment is almost contained and the flows of sediment act in dynamic equilibrium
Why might the dynamic equilibrium of a sediment cell be upset in the long-term?
Because of human intervention
Why might the dynamic equilibrium of a sediment cell be upset in the short-term?
Natural variations may interrupt it
What is found within each sediment cell?
Smaller subcells
Inputs
May refer to material or energy inputs
What are the main three areas of inputs at the coast?
- Marine
- Atmosphere
- Humans
What do marine inputs include?
Waves, tides, salt spray
What do atmospheric inputs include?
Sun, air pressure, wind speed and direction
What do human inputs include?
Pollution, recreation, settlement, defences
Outputs
May refer to material or energy outputs
Examples of outputs
- ocean currents
- rip tides
- sediment transfer
- evaporation
Stores/sinks
Refers to the stores and sinks of sediment and material
Examples of stores and sinks
- beaches
- sand dunes
- spits
- bars and tombolos
- headlands and bays
- nearshore sediment
- cliffs
- wave-cut notches
- wave-cut platforms
- caves
- arches
- stacks
- stumps
- salt marshes
- tidal flats
- offshore bands and bars
Transfers/flows
The processes that link the inputs, outputs and stores in the coastal system
Types of transfers/flows
- wind-blown sand
- mass movement processes
- longshore drift
- weathering
- erosion
- transportation
- deposition
Transfers/flows: erosion examples
- hydraulic action
- corrosion
- attrition
- abrasion
Transfers/flows: transportation examples
- bedload
- in suspension
- traction
- in solution
Transfers/flows: deposition examples
- gravity settling
- flocculation
Energy
The power and driving force behind the transfers and flows in the system
Types of energy sources
- wind
- gravitational
- flowing water
Give some sediment sources
- rivers
- cliff erosion
- wind
- glaciers
- offshore
- longshore drift
Sediment sources: rivers
- account for majority of sediment in the coastal zone
- sediment may be deposited in estuaries, which are brackish and important wildlife habitats
Sediment sources: cliff erosion
- very important in areas with unconsolidated cliffs that are eroded easily
- most erosion occurs during the winter months due to more frequent storms
Sediment sources: wind
- the wind is a coastal energy source and can cause sand to be blown along or up a beach
- sediment transport by winds may occur where there are sand dunes, or in glacial and desert environments which provide sediment inputs
Sediment sources: glaciers
- glaciers can flow directly into the ocean, depositing sediment that was stored in the ice when they calve
Sediment sources: offshore
- sediment is transferred to the coastal zone when waves, tides and currents erode offshore sediment sinks, such as offshore bars. The sediment is transported onto the beach, helping to build up the beach
Sediment sources: longshore drift
- sediment is moved along the beach, due to prevailing winds, which alter the direction of the waves
- this allows sediment to be transported from one section of coastline (as an output) to another stretch of coastline (as an input)
Give two factors that can disrupt the state of dynamic equilibrium at the coast
- human actions
- natural variation in the system
What is the littoral zone?
The area of land between the cliff’s or dunes on the coast and the offshore area that is beyond the influence of the waves
Why is the littoral zone constantly changing?
Because of short-term and long-term factors
What short-term factors impact the littoral zone?
- tides
- storm surges