Coasts: Systems and processes - Sediment sources, cells and budgets

Question 1

What are the sources of sediment in a coastal system?

Answer 1

Rivers
Cliff erosion
Longshore drift
Wind
Offshore sand banks
Glaciers

Question 2

Where does most coastal sediment originate from?

Answer 2

Rivers

Question 3

How do rivers input sediment into the coastal system?

Answer 3

Sediment is transported in rivers and is deposited in river mouths and estuaries where it is then reworked by waves, tides and currents

Question 4

How does longshore drift input sediment into the coastal system?

Answer 4

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

Question 5

How does offshore sediment enter the coastal system?

Answer 5

Waves, tides, currents, and storm surges

Question 6

What are sediment cells?

Answer 6

Distinct areas of coastline separated by well-defined boundaries such as headlands and stretches of deep water, which can each be seen a system.

Question 7

How many sediment cells are there along the coastline of England and Wales?

Answer 7

11

Question 8

Are sediment cells closed or open systems?

Answer 8

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.

Question 9

How do glaciers input sediment into the coastal system?

Answer 9

When ice shelves calve they can deposit the sediment trapped within the ice

Question 10

Describe the sizes of sediment cells.

Answer 10

Sediment cells vary in size - the larger ones are divided into sub cells

Question 11

Why are larger sediment cells divided into sub cells?

Answer 11

To allow closer study and management

Question 12

Give an example of a sediment sub cell.

Answer 12

The Holderness coast - between Flamborough Head and Humber Estuary of the east coast of England

Question 13

What is a sediment budget?

Answer 13

The balance between sediment being added to and removed from a sediment cell

Question 14

What is required to calculate the sediment budget for a sediment cell?

Answer 14

The identification of all the sediment sources and sinks, and an estimation of the amount of sediment added and removed each year.

Question 15

What does a net accretion of material in a sediment cell result in?

Answer 15

A positive sediment budget

Question 16

What does the net removal of material in a sediment cell result in?

Answer 16

A negative sediment budget

Question 17

How does a positive sediment budget impact the movement of the shoreline?

Answer 17

The shoreline builds towards the sea

Question 18

How does a negative sediment budget impact the movement of the shoreline?

Answer 18

The shoreline retreats landward

Question 19

Give an example of how the dynamic equilibrium of a sediment budget can be upset.

Answer 19

An flood can cause an increase in river sediment, leading to deposition in the river estuary

Question 20

What are sediment sinks?

Answer 20

Destinations where sediment that is permanently lost to a system