sediment sources Flashcards
where does sediment come from
streams or rivers:
- bring fine material
estuaries
cliff erosion
offshore sand banks
shells
what is seabed disturbance
storms destabalise material on sea floor and move to coast
what is sediment cell
length coastline where movement sediment self contained
balance between erosion and deposition
how many sediment cells in england and wales
11
size varies
boundaries separate them
LSD redistributes sediment from source to sik
largest ones have subcells that can interact
are sediment cells open or closed syst
theoretically closed
but easy for fine sediment move to adjacent cells round headland
sediment cells as a system
input:
-sometimes rivers,subaerial syst
-always LSD and offshore banks
-shells
-man generated
output:
-dune erosion
-wind erosion
-dredging
stores:
- beach
-spit
-bar
tranfer
- lsd
process
-erosional
- depositional
what to think when sediment q
exposure
rock type
coast defence
rivers
positive sediment budget
more added than removed
surplus
coast builds toward sea (accretion)
negative sediment budget
more removed than added
deficit
shoreline retreats
example of cell
swanage bay coastline cell
N to S rock types:
chalk
wealden clay
purbeck limestone
portland limestone
other sediment cell example
south down sediment cell
selsey bill to beachy head
why is south downs cell considered system
self contained - closed - but do get fine from river so could spread
could be open as allows mass and energy transfer across system boundary
people affect south downs cell
breakwaters in newhaven so more sediment there
- starved seaford beach
shoreham harbour 32000m3 dredged
unatural
