Sediment cells, sources and budgets Flashcards
(20 cards)
Name 4 sediment sources into the coastal system
Rivers, cliff erosion, longshore drift and wind
Where does the majority of sediment in the coastal system come from?
Rivers
How do rivers input sediment into the coastal system/
Sediment is deposited in river mouths and estuaries where it’s reworked by waves, tides and currents. Usually occurs most in high rainfall environments.
How is cliff erosion a sediment input into the coastal system?
The extensive till cliffs (made of sand and clay) are eroded and this material then ends up onshore, in the coastal system. e.g Holderness Coastline’s cliff contributes to sediment
How is longshore drift a sediment input into the coastal system?
Sediment transported from one area of coast to another.
How is wind a sediment input into the coastal system?
Wind can move loose sands and deposit them into coastal regions.
What are sediment cells?
Closed systems that are marked by headlands, estuaries or deep water to separate them.
How many sediment cells are there in the UK?
11 sediment cells
Give an example of an input into a sediment cell
Rivers/ coastal erosion
Give two examples of transfers in a sediment cell
Longshore drift/ ocean currents
Give two examples of stores in a sediment cell
beaches/ sand dunes/ offshore deposits
What are sediment subcells?
Smaller sub cells of the 11 sediment cells to look into the processes closer.
What is sediment budget?
The balance between sediment being added to and then removed from the coastal system.
What is a surplus/ positive sediment budget?
When more material is added to the cell than removed.
What is a deficit/ negative sediment budget?
More material is removed than added.
In theory, what does the sediment budget aim for?
Dynamic equilibrium where erosion and deposition are balanced.
What are sediment sinks?
Places where the dominant process is deposition, such as spits, estuaries and offshore bars
What are sediment subsinks?
Places where deposition may be temporary e.g beaches, dunes etc.
What is lithology?
The characteristics of the rock e.g its resistance
How can lithology impact the shape of the coastline?
- how easily rocks can erode e.g basalt more resistant than chalk
- structure of rock - discordant/ concordant causing differential erosion
