Topic3(1)- Coastal System

Question 1

Inputs

Answer 1

Sediment brought into the coastal system

Question 2

Examples of inputs

Answer 2

1) rivers carry eroded sediment from inland
2) sea level rise can flood river valleys forming estuaries which has sediment
3) erosion of cliffs
4) crushed shells of marine organisms
5) offshore deposits

Question 3

Positive sediment budget

Answer 3

If more sediment enters than leaves the coastal system

Question 4

Outputs

Answer 4

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

Question 5

Dynamic equilibrium

Answer 5

Inputs and outputs are balanced

Question 6

Negative feedback

Answer 6

When a change in the system causes other changes that have the opposite effect
E.g. as a beach is eroded, the cliffs behind it are exposed to wave attack. Sediment eroded is deposited on the beach causing it to grow in size again

Question 7

Positive feedback

Answer 7

When a change in the system causes other changes that have a similar effect.
E.g. as a beach starts to form it slows down the waves, causing more sediment to be deposited, increasing the beach size

Question 8

Flows/ transfers

Answer 8

Processes such as erosion, weathering, transportation and deposition; moving sediment within a system

Question 9

Stores/ components

Answer 9

Landforms such as beaches, dunes and spits

Question 10

Two ways by which energy is transferred in the coastal system

Answer 10

Wind and waves (Tides and currents)

Question 11

Winds (source of energy)

Answer 11

• created by air moving from high to low pressure
• during storms, the pressure gradient is high causing winds to be very strong
• stronger winds= powerful waves
• prevailing wind( wind travels for longer in same direction) causing higher energy waves

Question 12

Waves (source of energy)

• what causes circular motion in waves?
• whats wave height affected by?
• what is swash/backwash?

Answer 12

• created by the wind blowing over the sea
• the friction between wind and sea surface gives water a circular motion
• the effect of a wave on the shore depends on its height
• wave height is affected by wind speed and the wave fetch
• as waves approach the shore they break(friction with sea bed) the crest of the wave rises up and collapses
• water washing up beach is the swash; water washing towards sea is backwash

Question 13

Constructive waves

Answer 13

Low frequency(6-8 waves per min)
Low and long(more elliptical cross profile)
Powerful swash-deposits material up beach

Question 14

Destructive waves

Answer 14

High and steep
More circular cross profile
Higher frequency (10-14 waves per min)
Strong backwash removes material from beach

Question 15

Tides (source of energy)
What are they?
Where are most landforms created?

Answer 15

• the periodic rise and fall of the ocean surface (caused by gravitational pull of Moon and Sun)
• they affect the position at which waves break (At higher tide they break higher up the shore)
• area between maximum high tide and minimum low tide is where most landforms are created/destroyed

Question 16

Currents (source of energy)

Answer 16

• the general flow of water in one direction, caused by wind or change in water temp.& salinity
• the move material along the coast

Question 17

High energy coasts

• caused by?
• characteristics?
• dominant process?

Answer 17

• high inputs of energy via large, powerful waves (can be caused by strong winds,long fetches and steeply shelving offshore zones)
• tend to have sandy coves, rocky landforms
• erosion rates higher than deposition

Question 18

Low energy coasts

• caused by?
• characteristics?
• dominant process?

Answer 18

• receive low inputs of energy via small, gentle waves (caused by gentle winds(sheltered) short fetches and gently sloping offshore zones))
• some coasts are low energy as there is a reef or island offshore protecting coast from waves
• often have saltmarshes or tidal mudflats
• rate of deposition higher than erosion

Question 19

Sediment cells

Answer 19

• Coast is divided into these, also known as Littoral cells
• they are self-contained for the movement of sediment
• therefore, processes in one cell doesn’t affect the movement of sediment in another cell
• each cell is a closed coastal system

Question 20

4 sources of energy in coastal systems

Answer 20

Wind
Waves
Tides
Currents