4. Sediment Sources, Cells And Budgets Flashcards
What are the sources that crustal sediments come from?
Seabed Estuaries Rivers Cliff erosion Biological origin (shells, marine organism skeletons, coral)
How does the sea bed supply sediment?
Rising sea levels over the past 18,000 years have meant that sediment from continental shelf areas has been swept towards the shoreline
How do rivers contribute to the sediment budged?
Rivers make up 90% of coastal sediment
A combination of bedload shingle and suspended silt and clay
How does cliff contribute sediment?
Coastal sub-aerial (land-based) processes erode material
Contribute less than 5%
What are the sediment sources of biological origin?
Shells, corals etc
Small percentage composition
How many sediment cells is the UK made up of?
11
What is a sediment cell?
A distinct area in which sediment movement occurs
Sections are called sub-cells
What is the sediment budget?
The balance between sediment being added to and removed from the coastal system
What effects whether the sediment budget is positive or negative?
Positive- more material is added that removed, a creation of material, shoreline builds to sea
Negative- more material is removed than added, shoreline recedes landward
Why is calculating sediment budgets difficult?
All possible inputs, stores and outputs of sediment need to be identified
What separates sediment cells?
Well defined boundaries- headlands/stretches of deep water
What is the coastal sediment budget?
The balance between sediment being added to and removed from the coastal system
What sediment budget change would lead to the shoreline building up towards the sea?
More material added than removed
Net accretion of materials
Positive budget/surplus sediment
What sediment budget change would lead to the shoreline retreating landwards?
More material removed than added
Negative budget/deficit
