Coastal Processes
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- Created by: Evie :)
- Created on: 11-06-22 13:08
What direction is the prevailing wind?
The direction which the wind usually approaches from
Short term changes may affect this direction
Short term changes may affect this direction
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wave characteristics:
What is the fetch
What is the fetch
The distance of open water which a wave has passed
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What is the crest
The highest point of a wave
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What is the trough
The lowest point of a wave
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What is the wave height
The vertical distance between the highest and lowest points
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what is the wave lenth
Horizontal distance between 2 separate high points of waves
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What is the swash
Water movement up a beach
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What is the backwash
Water movement down a beach
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What does wave energy depend on?
- length of the fetch
- strength of the wind
- length of time the wind has blown for
- strength of the wind
- length of time the wind has blown for
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What happens when a wave breaks up the beach?
- Waves have a circular orbit
- The orbit becomes eliptical due to shore friction slowing the base of wave
- The breaking wave gains height
- The orbit becomes eliptical due to shore friction slowing the base of wave
- The breaking wave gains height
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Characteristics of constructive waves?
- form in the open ocean
- low, surging waves with long wavelength
- long waves, which roll onto beach with strong swash and weak backwash
- they promote growth on the beach(accretion)
- Over time they build up the beach to make it steeper
- low, surging waves with long wavelength
- long waves, which roll onto beach with strong swash and weak backwash
- they promote growth on the beach(accretion)
- Over time they build up the beach to make it steeper
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Characteristics of destructive waves?
- Local storms are responsible for their formation
- They are high plunging waves with short wavelength
- Tall waves crash onto the beach with a weak swash and strong backwash
- They remove sediment from a beach
- Over time they flatten the beach
- They are high plunging waves with short wavelength
- Tall waves crash onto the beach with a weak swash and strong backwash
- They remove sediment from a beach
- Over time they flatten the beach
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Characteristics of low energy coasts
- waves are not powerful
- The rate of deposition exceeds the rate of erosion (surplus)
- Characteristic landforms are beaches and spits (depositional)
- The rate of deposition exceeds the rate of erosion (surplus)
- Characteristic landforms are beaches and spits (depositional)
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Characteristics of high energy coasts
- waves are powerful
- rate of erosion exceeds the rate of deposition (deficit)
- Characteristic landforms are headlands, cliffs and wave cut platforms (erosional)
- rate of erosion exceeds the rate of deposition (deficit)
- Characteristic landforms are headlands, cliffs and wave cut platforms (erosional)
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Where in the UK are there high and low energy coastlines?
High energy- In the SW (long fetch)
Low energy- In the S, SE (short fetch)
Low energy- In the S, SE (short fetch)
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What are tides?
The regular rise and fall in sea level caused by the gravitational pull of the sun and moon on the oceans
the moon has the greatest influence, as it is nearer
the moon has the greatest influence, as it is nearer
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What are the different types of tides?
Solar tide- caused by the sun
Lunar tide- caused by the moon
Lunar tide- caused by the moon
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How do the sun and moon interact to form different tides?
Both pull water towards it
- Where the moon pulls water it creates the lunar bulge and there is a compen bulge on the opposite side of the earth
- as the moon orbits the earth , the high tide follows it
- the solar bulge caused by suns gravity, compen bul
- Where the moon pulls water it creates the lunar bulge and there is a compen bulge on the opposite side of the earth
- as the moon orbits the earth , the high tide follows it
- the solar bulge caused by suns gravity, compen bul
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What are 2 other types of tide?
The spring and neap tide
They are dependent upon the relative positions of the sun and moon
They are dependent upon the relative positions of the sun and moon
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How does a spring tide occur?
when the gravitational pull of the sun and moon are along the same axis
The forces work together to create a higher tide, as well as a lower tide
They occur every 14 days
The forces work together to create a higher tide, as well as a lower tide
They occur every 14 days
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How does a neap tide occur?
Occurs when the gravitational pull of the sun and moon are at 90 degrees to each other
- This results in their forces acting against each other, so the solar and lunar tidal bulges are separated
- This orientation results in a lower high tide and a highe
- This results in their forces acting against each other, so the solar and lunar tidal bulges are separated
- This orientation results in a lower high tide and a highe
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What are moon phases?
The shape of the moons sunlit portion when viewed from the earth
The amount of moon lit can help us to determine the relative positions of the sun and moon with the earth, which tells us what type of tide is being experienced
The amount of moon lit can help us to determine the relative positions of the sun and moon with the earth, which tells us what type of tide is being experienced
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What is the tidal range?
the vertical difference in the height of seawater at high and low tide
classifications
macrotidal- 4m+
mesotidal- 2m-4m
microtidal- less than 2m
low range- med/ high range- UK
classifications
macrotidal- 4m+
mesotidal- 2m-4m
microtidal- less than 2m
low range- med/ high range- UK
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What are synoptic charts?
used by meteorologists to study the weather
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Features of synoptic charts:
Isobars
Isobars
Lines on a weather map joining together places of equal atmospheric pressure
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Warm front
The transition zone where a warm air mass is replacing a cold air mass
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Cold front
The transition zone where a cold air mass is replacing a warm air mass
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occluded front
The point where a cold front takes over a warm front, or the other way around
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What is a storm surge?
A change in sea level that is caused by a storm
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What causes storm surges?
High winds blowing towards the shore, pushing the sea water towards the coast
Low pressure at the centre of storm pulls the water level up
Spring tides cause high tides
Low pressure at the centre of storm pulls the water level up
Spring tides cause high tides
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What are the impacts of storm surges?
extensive flooding
damage to sea defences
particularly from strong winds, which generate large waves on top of surge
damage to sea defences
particularly from strong winds, which generate large waves on top of surge
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What is a negative storm surge?
when the wind direction blows the water away from the coast instead, causing the sea level to drop
these are less dangerous
they can damage ships in ports and leave them stranded until the water level rises again
these are less dangerous
they can damage ships in ports and leave them stranded until the water level rises again
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where was an example of a storm surge?
Suffolk- 2013
2m surge above tide level
High tides
Winds moved north westerly so the surge moved along the shore
2m surge above tide level
High tides
Winds moved north westerly so the surge moved along the shore
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What were the impacts of the storm surge along the east coast?
- Barriers breached which protected homes
- 7 homes toppled off cliff
- 2 dead
- Amusement arcade and fish shops flooded(Hornsea)
- Many people evacuated in suffolk/norfolk
- 7 homes toppled off cliff
- 2 dead
- Amusement arcade and fish shops flooded(Hornsea)
- Many people evacuated in suffolk/norfolk
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What are rip currents?
Strong offshore Cs that often occur when breaking waves push water up the beach surface->this piled up water esapes out to sea->If there is an area where water can flow back (break in sand bar) a rip current can form
once formed they modify the beach
once formed they modify the beach
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What do ocean currents do?
Transport heat around the earth, from the equator to the poles
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What causes water to rise and fall within oceans?
Salt content- if there is more salt the water is more dense and the water level falls
temperature- if the water is warmer it is less dense and the level rises
temperature- if the water is warmer it is less dense and the level rises
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Which ocean current affects the UK?
The gulf stream
It keeps us warm , as warm water is transported to the UK
It keeps us warm , as warm water is transported to the UK
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What is the distribution of ocean currents around the world?
The cycles are always west
warm currents above the equator travel northwards , taking warm water to the poles
Cold currents above the equator travel southwards, taking cold water to the equator
warm currents above the equator travel northwards , taking warm water to the poles
Cold currents above the equator travel southwards, taking cold water to the equator
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Different ocean currents:
Surface ocean currents?
Surface ocean currents?
Located at the surface
they are typically wind driven, resulting in horizontal and vertical water movement
they are typically wind driven, resulting in horizontal and vertical water movement
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What are horizontal surface currents?
Typically local and short term/e.g, rip currents, tidal currents, upwelling curents- involve vertical water movement and bring cold water towards the surface and pull warm, less dense water downward where it condenses and sinks this causes a cycle of upwe
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What are deep ocean currents?
they are density driven and slow moving
They occur in deep water below 300m
They occur in deep water below 300m
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what are warm surface currents
they carry warm water with a low density away from the equator near the waters surface
Cold- carry cold denser water from the poles to the equator
Cold- carry cold denser water from the poles to the equator
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What is LSD?
LSD is a coastal current responsible for moving sediment along the coast
this usually occurs in one direction which is dictated by the prevailing wind
this usually occurs in one direction which is dictated by the prevailing wind
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How does LSD operate on the Holderness Coastline?
The prevailing wind along the HC is north easterly
Due to the wind direction waves break onto the beach at an angle of around 40-45 degrees
the swash moves beach material along the beach
Due to the wind direction waves break onto the beach at an angle of around 40-45 degrees
the swash moves beach material along the beach
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why is LSD important?
Without LSD depositional landforms wouldn't form//it is a very important component to a sediment cell and if interrupted by management strategies it can lead to distortion of the natural system
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Other cards in this set
Card 2
Front
wave characteristics:
What is the fetch
What is the fetch
Back
The distance of open water which a wave has passed
Card 3
Front
What is the crest
Back
Card 4
Front
What is the trough
Back
Card 5
Front
What is the wave height
Back
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