Coasts As A System Flashcards
What are the inputs of coasts as a system?
- Energy from the wind
- Waves and tides
- Sediment from weathering and erosion processes
What are the stores in a coastal system ?
Sediment deposited in Land forms
E.g beaches
What are the transfers in a coastal system?
Processes of erosion
Processes of transportation that can move Sediment around the system
What are the outputs in a coastal system
Sediment is removed by long shore drift
Sediments are deposited as landforms such as dunes
Define the coast as a system
The coast is an open system. Energy and Sediment can move from the boundary of the system into the environment around it.
What is the sediment budget?
The balance between the input, store and outputs of sediment.
What does anthropogenic mean?
Activity originating from humans
Natural inputs of coastal sediment budget
Sediment from anything below:
Coastal stores ( marshes/dunes )
Cliffs
Rivers
Offshore
Natural outputs of the coastal sediment budget
Sediment deposited in any of the following:
Coastal stores ( marshes/dunes )
Offshore during storms
Estuarine sedimentation
Process that transfers sediment in the coastal sediment budget
Long shore drift ( transfers in and out of the budget )
What are the anthropogenic inputs of the coastal sediment budget ?
Beach nourishment - humans depositing sand or other sediment into beaches from other sources - helps prevent erosion
Dune building - the process of building artificial sand dunes to provide coastal erosion defences
What are the anthropogenic outputs of the coastal sediment budget?
Land claim -A land claim is a legal declaration of desired control over areas of property, including bodies of water
Dredging - Humans removing sediment from the seabed for industrial use
Beach mining - The extraction of sand from beaches for industrial use for things like glass and concrete
If something was out of balance in the sediment budget what would be the impact?
It could increase erosion further along the coastline
Describe the sediment budget when input sediment = output sediment
The sediment budget is in a steady-state equilibrium
What is a sediment cell?
A sediment cell is a stretch of coastline where the sediment budget is self contained. It is also know as a littoral cell
There are 11 major sediment cells for England and Wales.
The sediment cells can be described as an open system. Why is this ?
Because Sediment can be lost from the cells which makes it an open system
Coasts are constantly changing due to variations in the energy conditions, such as storms.
When is a coast in equilibrium?
When both the inputs and the outputs of the system are equal
Describe steady state equilibrium
When changes in energy and resulting change in coastlines do not vary much from the long-term average conditions
For example when the beach profile adjusts in summer and winter due to the wave energy changes but the average gradient stays the same
Describe Metastable equilibrium
The coastal zone changes from one state of equilibrium to another due to an event causing a change in conditions
For example Sediment removed due to dredging changes the beach profile of it disappears. There is a new equilibrium with a reduced beach
Describe dynamic equilibrium
The state of equilibrium changes over a longer timescale than metastable equilibrium
For example climate change. Causing rising sea levels allows new areas of land to be influenced by wave attack, resulting in a change in cliff profile
What is feedback?
Feedback occurs as a result of a change in the coastal system, helping the system adjust
What is positive feedback?
Increases the initial change that occurred
What is negative feedback?
Reduces the effect of the change, helping the coast return to its original condition
