Sediment Cells

Question 1

Sediment cells

Answer 1

. A sediment cell is a stretch of coastline within which sediment movement is more or less contained
. These cells are generally bordered by 2 large headlands or deep water and contain inputs, transfers and stores of sediment
. In total there are 11 Cells around the UK which are then divided further into sub cells

Question 2

Sediment cells and dynamic equilibrium

Answer 2

. In theory within a sediment cell there should be a state of dynamic equilibrium between inputs via erosion and other methods and losses of material to deposition in sinks.
. In reality it is very unlikely that a system will be in perfect equilibrium due to human intervention or unexpected events (e.g. storm surges which add material) which may add or remove material outside of the system.

Question 3

Sinks (store)

Answer 3

Beaches, sand dunes and offshore bars/banks/bands

Question 4

Transfers (flows)

Answer 4

Longshore (littoral) drift as well as onshore and offshore processes such as winds and currents

Question 5

Sources of sediment (rivers)

Answer 5

. Sediment that is transported in rivers often accounts for the vast majority of coastal sediment, especially in high-rainfall environments where active river erosion occurs.
. This sediment will be deposited in river mouths and estuaries where it will be reworked by waves, tides and currents.

Question 6

Sources of sediment (cliff erosion)

Answer 6

This can be extremely important locally in areas of
relatively soft or unconsolidated rocks. The extensive till cliffs along the Holderness coast in Lincolnshire comprise sand and clay and rates of erosion can be as high as 10 m a year. This contrasts wich
the tough, igneous granites in Cornwall that erode at very slow rates.

Question 7

Sources of sediment (LSD)

Answer 7

Sediment transported from one stretch of coastline as an output to another stretch of coastline as an input

Question 8

Sources of sediment (wind)

Answer 8

In glacial or hot arid environments, wind blown sand can be deposited in coastal regions. Sand dunes are semi-dynamic features at the coast that represent both accumulations of sand and potential sources.

Question 9

Sources of sediment (glaciers)

Answer 9

In some parts of the world, such as Alaska, Greenland and Antarctica, ice shelves calve (chunks of ice breaking off a glacier or ice into the sea depositions trapped sediment within the ice

Question 10

Sources of sediment (offshore)

Answer 10

Sediment from offshore can be transferred into the coastal (littoral) zone by waves, tides and currents. In the UK, sea levels rose at the end of the last glacial period, resulting in a considerable amount of coarse sediment being bulldozed onto the south coast of England to form landforms like barrier beaches
Storm surges also input sediment