2. Sources Of Energy In Coastal Environments

Question 1

Describe how wind acts as the primary source for other processes.

Answer 1

Creates waves due to fractional drag
Length of fetch determines the size and energy of waves
Many coastlines have a prevailing wind direction
Spatial variation in energy as the result of varying wind strength and duration
Energy of a wave depends on the strength of wind, it’s duration and the length of fetch

Question 2

What is a wave?

Answer 2

Undulations on the surface of the sea driven by wind

Question 3

What are the key features of a wave?

Answer 3

Height
Length
Frequency

Question 4

Define wave height.

Answer 4

The difference between the crest and trough of a wave

Question 5

Define wave length.

Answer 5

The distance between two crests (or troughs)

Question 6

Define wave frequency.

Answer 6

The time between one crest and the following crest passing a fixed point

Question 7

Describe the functioning of a wave.

Answer 7

Wave enters shallow water
Friction with the seabed increases
Wave slows
Increases in height
Plunges or breaks into shoreline

Question 8

What is the difference between swash and backwash?

Answer 8

Swash is the wash of water up the beach

Backwash is the drag of water back down the beach

Question 9

Describe constructive waves.

Answer 9

Low, long length (up to 100m)
Low frequency (6/8 per minute)
Gentle approach to shoreline
Swash loses volume and momentum, leading to weak backwash so sediment movement off the beach is low
Material is slowly moved up the beach
Forms berms

Question 10

Describe destructive waves.

Answer 10

High, steep
High frequency (10/14 per minute)
Rapid approach to shoreline
Little swash, powerful backwash so sediment is pulled away from the beach
Little material moved up the beach
Forms storm beaches

Question 11

What is wave refraction?

Answer 11

The process by which waves break into an irregularly shaped coastline, such as a headland separated by two bays
Becoming increasing parallel to the coastline

Question 12

Describe the function of wave refraction.

Answer 12

Wave drag in the shallow water approaching a headland
Wave becomes high, steep and short
Part of the wave in deeper water moves forward faster
The wave bends
The low energy wave spills into the bays as most of the wave is concentrate on the headland

Question 13

What are currents?

Answer 13

The permanent or seasonal movement of water in the seas and oceans
Three types

Question 14

What are the three types of current?

Answer 14

Longshaw currents
Rip currents
Upwelling

Question 15

Describe longshaw currents.

Answer 15

Most waves approach the shoreline at an angle
This creates a current of water running parallel to the shoreline
Effect: transports sediment parallel to the shoreline

Question 16

Describe rip currents.

Answer 16

Strong currents moving away from the shoreline due to a build up of seawater and energy along the coastline
Effect: hazardous for swimmers

Question 17

Describe upwelling.

Answer 17

The global pattern of currents circulating in the oceans can cause deep, cold water to move toward the surface, displacing the warmer surface water
Effect: a cold current rich in nutrients

Question 18

ADD TIDES IN

Answer 18

tiddies

Question 19

What is fetch?

Answer 19

The distance of open water over which a wind blows uninterrupted by major land obstacles

Question 20

How are waves formed?

Answer 20

By the transfer of energy from the wind blowing over the sea surface

Question 21

How does wind act as an agent of erosion?

Answer 21

Wind can pick up and remove sediment which can be used to erode other features (abrasion)

Question 22

How does shallow water change a wave?

Answer 22

Friction with the seabed occurs
The base of the wave slows down
Wave height and steepness is increased
The upper part plunges forward and the wave breaks on shore

Question 23

Define tides.

Answer 23

The periodic rise and fall of the level of the sea in response to the gravitational pull of the sun and moon

Question 24

How does the moon impact tides?

Answer 24

It is closer to earth than the sun
It pulls water towards it, creating high tides
There is a compensatory bulge on the opposite side of the earth
In between the two blushes, the tide is at its lowest

Question 25

What is spring tide?

Answer 25

When the moon, son and watch are in a straight line
The tide-raising force is strongest
Twice in a lunar month

Question 26

What are neap tides?

Answer 26

When the sun and moon are perpendicular to each other in relation to the earth
Gives lowest monthly tidal range (10-30% lower than average)

Question 27

What can modify the regular pattern of tides?

Answer 27

Morphology of the seabed
Proximity of land masses
The impact of spinning forces of the earth

Question 28

What is tidal range?

Answer 28

The difference in height of the sea water at high and low tide
Not fixed

Question 29

What is determined by tidal ranges?

Answer 29

The upper and lower limits of erosion and deposition

The amount of time the littoral zone is exposed to sub-aerial weathering

Question 30

What are tidal/storm surges?

Answer 30

When meteorological conditions give rise to strong winds which produce higher water levels than those at high tide

Question 31

Why is the North Sea heavily effected by tidal/storm surges?

Answer 31

Intense low pressure weather systems over the North Sea produce low pressure conditions that raise sea levels
Strong winds drive waves agreed if the storm, pushing sea toward the coastline so it ‘piles up’ against the coast
The shape of the North Sea means the water in concentrated into a space that is decreasing in size

Question 32

Give examples of tidal surges.

Answer 32

North Sea- 1953

East coast England- 2013/2014 (Cromer pier) (higher water levels than 1953)