Coasts: Systems and processes - Sediment sources, cells and budgets Flashcards
Sediment sources, cells and budgets
What are the sources of sediment in a coastal system?
Rivers Cliff erosion Longshore drift Wind Offshore sand banks Glaciers
Where does most coastal sediment originate from?
Rivers
How do rivers input sediment into the coastal system?
Sediment is transported in rivers and is deposited in river mouths and estuaries where it is then reworked by waves, tides and currents
How does longshore drift input sediment into the coastal system?
Sediment is transported from one stretch of coastline as an output to another stretch of coastline as an input
How does offshore sediment enter the coastal system?
Waves, tides, currents, and storm surges
What are sediment cells?
Distinct areas of coastline separated by well-defined boundaries such as headlands and stretches of deep water, which can each be seen a system.
How many sediment cells are there along the coastline of England and Wales?
11
Are sediment cells closed or open systems?
In theory they are seen as closed systems from which nothing is gained or lost, however in reality it is easy for fine sediments to find their way around headlands and into adjacent cells.
How do glaciers input sediment into the coastal system?
When ice shelves calve they can deposit the sediment trapped within the ice
Describe the sizes of sediment cells.
Sediment cells vary in size - the larger ones are divided into sub cells
Why are larger sediment cells divided into sub cells?
To allow closer study and management
Give an example of a sediment sub cell.
The Holderness coast - between Flamborough Head and Humber Estuary of the east coast of England
What is a sediment budget?
The balance between sediment being added to and removed from a sediment cell
What is required to calculate the sediment budget for a sediment cell?
The identification of all the sediment sources and sinks, and an estimation of the amount of sediment added and removed each year.
What does a net accretion of material in a sediment cell result in?
A positive sediment budget
