Coasts as Natural Systems Flashcards
What type of system is the coast?
An open system
What is an open system?
One which interacts strongly with other systems eg. sediment is often from rivers
What effect can feedbacks have on a system?
They can increase or decrease available inputs or outputs as well as enabling equilibrium
When is a system in dynamic equilibrium?
When inputs and outputs of energy and matter are balances
What type of events alter the coastline on a short term basis?
Storms
What can dynamic equilibrium be affected by over geological (longer) time periods?
Supply of sand
Energy of the waves
Sea level change
Location of the shoreline
What is a landform?
Individual features which are created by coastal processes
What is a landscape?
The entire area of sea, coastline and immediate land behind the sea front. Within the landscape are characteristic landforms
What are inputs?
Material or energy entering the system from outside sources/systems.
What are flows/transfers?
Processes that link the inputs, outputs and stores in the coastal system.
Movement of material and energy.
What are stores/sinks?
Parts of a system not necessarily in motion. Sediment and material.
What are outputs?
Material/energy moving out of a system
What are feedbacks?
Can be positive (leads to increase/amplification) or negative (leads to decrease/decline)
What are some of the inputs into the coastal system?
Energy
Precipitation
Wind
Fluvial Sediment
What are some of the flows/transfers in the coastal system?
Longshore drift
Mass movement
Weathering
Wind-blown sand
Erosion
Oceancurrents
Riptides
What are some of the outputs from the coastal system?
Ocean currents
Riptides
Sediment transfer
Evaporation
What is energy?
The power and driving force behind the transfers and flows in the system.
Wind
Gravitational
Flowing water
Example of a negative feedback loop
- When the destructive waves from the storm lose their energy excess sediment is deposited
as an offshore bar. - The bar dissipates the waves energy which protects the beach from further erosion.
- Over time the bar gets eroded instead of the beach.
- Once the bar has gone normal conditions ensue and the system goes back to dynamic
equilibrium.
Example of a positive feedback loop
- People walking over sand dunes destroys vegetation growing there and
causes erosion. - As the roots from the vegetation have been holding the sand dunes
together, damaging the vegetation makes the sand dunes more
susceptible to erosion. This increases the rate of erosion. - Eventually the sand dunes will be completely eroded leaving more of the
beach open to erosion taking the beach further away from its original state.
What are some of the stores in the coastal system?
● 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
