2.12 - How To Monitor Coastal Recession

Question 1

Glamorgan Heritage Coast

Answer 1

SSSI in South AWales
Series of alternating layers - limestone and clay
Exposed to Atlantic fetch and vulnerable to winter storms
2014 - Huge cliff collapse

Question 2

Overall Basic Principle

Answer 2

The rate of cliff retreat depends on the amount of contact time between the sea and the rock

Question 3

Fetch

Answer 3

Distance that waves travel uninterrupted, the longer the fetch, the faster recession is

Question 4

Wind Direction

Answer 4

Largest waves from prevailing wind direction, SW in Wales.

Question 5

Depression

Answer 5

Low pressure weather systems, more intense, faster wind speeds, leading to destructive waves.

Question 6

Anticyclones

Answer 6

High pressure, calmer conditions and smaller waves.

Question 7

Effects Of Seasons

Answer 7

An increase in wind will lead to an increase in waves, increasing erosion due to the effects of weather systems and SLR working together.

Question 8

Effects Of Weather Systems

Answer 8

Increasing sea levels change the shape of the coastline, contribution to coastal recession, flooding and more underground saltwater incursion.

Question 9

Effects Of Storms

Answer 9

Linked to depression, they’re likely to become more common. More intense tropical cyclones will exhibit even lower surface air pressure, producing large temporary sea level rises as storm surges approach, increasing coastal flood risk.

Question 10

Depression

Answer 10

Polar front jet stream will accelerate, possibly increasing the number and intensity of depressions and storm surges.

Question 11

Tidal Bulge

Answer 11

Once a day, the Earth rotates on its axis, the moon’s gravitational attraction pulls water towards it, creating a bulge.
Inertia always tries to counteract this, so on the far side water tries to move away, creating a ‘bulge’ on the opposite side.
The bulges stay aligned with the moon so as the Earth rotates you get high tide and low tide.

Question 12

Alignment

Answer 12

Once a month/fortnight, spring high tides happen as the sun/moon are aligned, so gravitational pull is at it’s strongest. The sun and moon also align every 2 weeks but the Earth is in the way. The lowest high tide (neap tide) are when the sun and moon are at right angles due to weaker gravitational pull

Question 13

Interaction

Answer 13

The moon rotates around the earth every month, it’s elliptical meaning it’s closer to Earth at sometimes than others. 4 times a year the proximity coincides with the spring high tide getting even higher spring high tides - perigean high tides.

Question 14

Why Isn’t Cliff Retreat Constant

Answer 14

Intertia may interact and reduce the effects of bulges
Hard engineering methods - groynes rock armour, sea walls
Rock Types - Some layers are more vulnerable
Human Interference - Coastal management however, land, houses, industry and infrastructure are cause for concern.

Question 15

Long Term Coastal Recession

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Answer 15

Tectonic Disasters - Disrupt the strata creating anticlines and synclines increasing coastal recession.
Tectonics - Magma rises the plate, which causes eustatic SLR.