Coastal systems and landscapes advanced information

Question 1

what is an input

Answer 1

Sediment can be brought into the system through wind, waves, tides, and currents.

Question 2

what is an output

Answer 2

Sediment can be washed out to sea or deposited further along the coast.

Question 3

What is a flow/transfer

Answer 3

Processes such as erosion, weathering, transportation, and deposition move sediment within a system.

Question 4

What is a store/component

Answer 4

Landforms such as beaches, dunes and spits are stores of sediment.

Question 5

What is dynamic equilibrium

Answer 5

Coasts are often in dynamic equilibrium where inputs and outputs are balanced. A change in one input or output causes negative feedback that restores balance.

Question 6

What is a negative feedback

Answer 6

When a change in a system causes other changes that have the opposite effect.

E.g beach eroded, exposes cliffs to wave attacks, sediment eroded from cliffs restores beach.

Question 7

What is positive feedback

Answer 7

When a change in a system causes other changes that have a similar effect.

E.g As a beach forms it slows down waves, causes more sediment to be deposited, increasing the size of the beach.

Question 8

How is wind a source of energy in coastal environments

Answer 8

Wind is created by air moving from areas of high pressure to areas of low pressure.

Strong winds can generate powerful waves. Prevailing winds where wind blows in the same direction for a long time can cause high energy waves.

Question 9

How are waves a source of energy in the coastal system

Answer 9

Created by wind blowing over the sea, the friction between them gives a circular motion to waves.

High wind speed and long fetch create higher waves. Friction with sea bed slows wave and makes it oval shaped then the crest of the wave rises up and collapses.

Question 10

What is a constructive wave

Answer 10

Low frequency.

Low and long.

Powerful swash to deposit material up the beach.

Question 11

What is a destructive wave

Answer 11

Higher frequency.

High and steep.

Strong backwash removes material from the beach.

Question 12

How are tides a source of energy

Answer 12

Tides are the periodic fall and rise of the ocean surface caused by the moons gravity.

Tides affect position waves break on the beach. Area of land between maximum high tide and minimum low tide is where landforms are destroyed and created.

Question 13

How are currents a source of energy

Answer 13

A current is the general flow of water in one direction caused by wind or by variations in temperature and salinity.

Currents move material along the coast.

Question 14

What is a low energy coast

Answer 14

Low input of energy meaning small gentle waves. Caused by gentle offshore winds. Often have saltmarshes or tidal mudflats. Rate of deposition is often higher than rate of erosion.

Question 15

What are the sediment sources in coastal systems

Answer 15

Rivers carry sediment from inland.
Sediment eroded from cliffs by waves and weathering.
Sediment from crushed shells of marine organisms.
Waves, tides and currents transport sediment into the coastal zone from off-shore deposits.

Question 16

What is a sediment budget

Answer 16

The difference between the amount of sediment that enters and leaves the system.

Positive sediment budget - coastline advances.
Negative sediment budget - coastline retreats.

Question 17

What is a sediment cell

Answer 17

Coast is divided into sediment cells. They are enclosed systems so sediment is not transported between them. Each cell is a closed coastal system.

Question 18

What is abrasion (type of erosion)

Answer 18

Bits of sediment carried by the waves are smashed against cliffs and rocks causing bits to fall off.

Question 19

What is hydraulic action (type of erosion)

Answer 19

Air in cracks in the cliff are compressed by water from waves. Causing high build up of pressure which causes rock to break off.

Question 20

What is cavitation (type of erosion)

Answer 20

As waves recede compressed air expands violently exerting pressure on the rock and causing bits to break off.

Question 21

What is wave quarrying (type of erosion)

Answer 21

Energy of a wave when it crashes against a rock is enough to break bits off.

Question 22

What is solution/corrosion (type of erosion)

Answer 22

Soluble rocks like chalk are gradually dissolved by the seawater.

Question 23

What is attrition (type of erosion)

Answer 23

Bits of rock in the water smash against each other and break.

Question 24

What is solution (type of transportation)

Answer 24

As sediment is dissolved in the water it is carried by the water like chalk when it’s dissolved in the water.

Question 25

What is saltation (type of transportation)

Answer 25

Larger bits of sediment like pebbles are too heavy to be carried in suspension so are bounced along the sea bed by the force of the water.

Question 26

What is suspension (type of transportation)

Answer 26

Very fine sediment such as clay is whipped up by turbulence and carried along by the water.

Question 27

What is traction (type of transportation)

Answer 27

Very large particles like boulders are pushed along the seabed by the force of the water.

Question 28

What is longshore drift (type of transportation)

Answer 28

When swash carries sediment up a beach parallel to the prevailing wind and backwash carries sediment down the beach at right angles to the shoreline.

Question 29

What is marine deposition

Answer 29

When sediment carried by seawater is deposited.

Question 30

What is aeolian deposition

Answer 30

When sediment carried by the wind is deposited.

Question 31

Why does deposition occur

Answer 31

When sediment load is exceeded by landslide for example.
Friction increases like waves in shallow water and wind over land the water or wind is slowed down.
Flow becomes turbulent such as a rock in the water.
If wind slows waves will also lose energy.

Question 32

What is salt weathering

Answer 32

Saline water enters cracks in rocks. As the tide goes out and water evaporates salt crystals form. As they form they expand and exert pressure on rock causing bits to break off.

Question 33

What is freeze-thaw weathering

Answer 33

Occurring areas where temperatures go above and below 0 degrees when water enters cracks in rocks and then temperature drops below 0 degrees the water will freeze and expand. This puts pressure on the rock causing bits to fall of.

Question 34

What is Chemical weathering

Answer 34

Breakdown of rock by changing its chemical composition. For example carbonic acid reacting with carboniferous limestone causing it to dissolve.

Question 35

What is wetting and drying (type of weathering)

Answer 35

Some rock contains clay. When it gets wet it expands. The pressure it exerts causes parts of the rock to break off.

Question 36

How does a saltmarsh/mudflat form

Answer 36

Form in sheltered, low energy environments like an estuary.
Silt and other sediment is deposited where the tide and river meet. Flocculation(particles hit into each other).
Mudflat forms.
Colonised by salt resistant halophytes. Vegetation then traps more silt and mud building saltmarsh upwards.
Less salt resistant vegetation can grow as the saltmarsh is submerged for a smaller period of time.

Question 37

What are coastlines of emergence

Answer 37

When sea level falls a new coastline emerges from the sea.

Question 38

What are fjords)

Answer 38

Fjords form from glacial cut valleys. They are narrow with very steep sides. They have a shallow mouth with a raised bit of ground called a threshold formed through deposition from the glacier. Can be up to 1000m deep in some places.

Question 39

What are the predicted impacts of climate change on coasts

Answer 39

Increases in temperature will cause a rise in sea level due to the melting of ice sheets and the thermal expansion of water.

Sea level currently rises by 2mm a year if greenhouse gas emissions remain high it is predicted to go up to 8-16mm a year by 2100.

Question 40

What is hard engineering

Answer 40

Building defensive structures.

Question 41

What is a sea wall

Answer 41

Absorbs wave energy and reflects it back out to sea.

Expensive to build and maintain and is ugly.

Question 42

What is a groyne

Answer 42

Fences built at right angles to the shoreline. Prevent longshore drift taking sediment away from the beach creating wider beaches.
Cheap to build but starves beaches down the coast.

Question 43

What is soft engineering

Answer 43

Involves coaxing natural processes along.

Question 44

What is beach nourishment

Answer 44

Sand is added to beaches from elsewhere making them wider and more resistant to erosion.

Question 45

What is beach stabilisation

Answer 45

Plants and vegetation is planted on beaches to stabilise them and make them wider which makes cliffs more resistant to erosion.

Question 46

Is hard or soft engineering more sustainable

Answer 46

Hard engineering interferes with natural processes and is expensive to maintain. Soft engineering is cheaper and only encourages natural processes. Therefore soft engineering is more sustainable.

Question 47

What is shoreline management

Answer 47

The coastline is split into sediment cells. All local authorities in the sediment cell come up with a plan called an SMP. The plan is devised to protect important sites without causing issues in other areas of the coastline. They can decide to hold the line, advance the line or do nothing.

Question 48

What is integrated coastal zone management

Answer 48

The water and land are seen as interdependent. The plan considers all aspects such as economic, social, land and sea when devising a strategy. Aims to protect the coastline in a relatively natural way. Considers different uses of the coastline like fishing or tourism. Local, regional and national authorities all have input into the plan.