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Geography > coasts EQ3 > Flashcards

coasts EQ3 Flashcards

1
Q

How does vegetation removal reduce flood risk?

A

An 100m of mangrove forest reduces the wave height by 40%
Mangroves stabilise sediments, trapping them and adding to them, keeping the level of coastal land higher
Reduce storm surge levels by 0.5m for every 1km of forest that seawater has to pass through

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2
Q

How much has sea levels risen since the last ice age?

A

Since 10000 years ago, the sea levels has risen by 120m

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2
Q

What is a result of coastal flooding on the nile delta?

A

Salt intrusion
Offshore bars eroded

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2
Q

What are location examples of a ria?

A

Plymouth sound - South west england.

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3
Q

What is an example of a human cause of coastal erosion?

A

Coastal defences
They stop or limit the supply of dediment to a cell, which means that another place down drift may not recieve sediment for beach building.

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4
Q

What are location examples of a fjord.

A

Milford sound in new zealand.

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4
Q

What is the projected rate of sea level rise by the end of the 21C

A

8-16mm a year

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4
Q

What would happen if sea levels rise by 1m on the nile delta coast?

A

2 million hectares of fertile land will be lost
< 6 million people displaced

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4
Q

How much % does thermal expansion lead to sea level rise

A

40% from 1990-2010 according to IPCC

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4
Q

How much of the Nile Delta land will be lost

A

3.3%

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5
Q

What is a ria?

A

Flooded river valley.
During an ice age, some areas were not covered in ice but the floor had frozen ground, so rivers carved vallys steeper than normal. The ice melted and the sea level flooded the valleys.

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6
Q

What are some location examples of raised beaches.

A

Forth, Clyde and tay valleys
North of Drumadoon on the isle of arran ( raised beach now 5m above sea level)

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7
Q

What are fossil cliffs?

A

A fossil cliff is a near vertical slope initially formed by marine processes but now some distant inland.

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8
Q

How much % of the Nile Deltas coast is highly vulnerable and low vulnerable

A

highly vulnerable - 34%
low vulnerable - 26%

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9
Q

Why is dredging causing increased erosion rates?

A

Deeper water caused by dredging allow waves to maintain their circular motion and energy closer inshore and be more destructive

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9
Q

What are perigean spring tides

A

When the moon is the closest to the earth

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10
Q

What conditions do low pressure areas have?

A

Air masses with different temperatures and air rising rapidly - so there are strong winds rotating in the anti clockwise direction, creating larger waves.

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10
Q

What is a fjord?

A

flooded glaciated valley.
During an iceage, glaciers eroded U-Shaped valleys down to the coast of the time and then melted. The sea level rose and flooded into the valley in a shallow threshold, creating a very deep water inlet and steep sides.

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10
Q

What is a fjard?

A

Flooded inlet with low rocky banks on either side formed by post glacial drowning.

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11
Q

What has the IPCC attributed global warming to

A

Anthropogenic forcing through greenhouse gas emissions

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11
Q

Why are high tides bad for erosion?

A

The waves are likely to reach the backshore and erode the land faster

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12
Q

What is isostatic rebound/recovery?

A

When the ice sheets melt, there is less pressure on the mantle and crust, causing the land to push back upwards.

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13
Q

What are spring tides?

A

Extreme high tides
When the sun and the moon are aligned - gravitational force is the strongest

13
Q

What are two human causes of coastal retreat/erosion?

A

Coastal defences
Offshore dredging

14
Q

What are dalmatian coastlines?

A

Are concordant coasts where the sea has flooded the landscape of alternating hills and valleys to create long bays and parallel hilly islands.

15
Q

Why is terminal groyne sydrome bad for the coast?

A

The beach gets narrower and is less able to absorb wave energy and waves hit the backshore with more force.

16
Q

How has climatic warming lead to a rise in eustatic sea level?

A

Melting of mountain glaciers increasing the amount of water in the ocean

17
Q

How does weathering accelerate coastal retreat?

A

Weakens the rocks found at the coast and allows erosion rates to increase

18
Q

How does mass movement accelerate coastal retreat?

A

Moves sediment to the base of the slope where wave action and lsd can carry material away. This exposes the base of coastal slopes

18
Q

What are local factors that increase coastal flood risk?

A

Height
Subsidence
Vegetation removal

18
Q

How does the wind direction and fetch affect rates of erosion?

A

Rates of recession will be higher when the wind is being blown onshore
When wind blows from the prevailing wind direction, strong winds produce large destructive waves
When wind blows from a direction with a large fetch, it causes large waves.

18
Q

What conditions do high pressure areas have?

A

calmer conditions and smaller waves

19
Q

What are examples of areas which are suffering from flood risks?

A

Maldives archipelago
Bangladesh
Kiribati archipelago

20
Q

What happens to sea levels when the climate warms up?

A

The ice on the land melts and returns water to the sea.

20
Q

What are tectonic changes?

A

As tectonic plates move and collide, continental shelves and areas of land are pushed upwards or sink downwards.
Tectonic activity can produce tsunamis.

21
Q

What are examples of submergent coastlines?

A

A ria, fjord, fjard, dalmatian coastline.

21
Q

What are the two examples of emergent coastlines?

A

Raised beach and fossil cliffs.

21
Q

What is isostatic change?

A

When the land rises or falls relative to the sea
Local change

21
Q

What is eustatic change?

A

Refers to the change in sea level
A global change
Mostly revolved around the melting and storing of ice glaciers, ice sheets

21
Q

How much % does melting ice sheets lead to sea level rise

A

50% from 1990-2010 according to IPCC

21
Q

What are neap tides?

A

Low tides
When the sun and the moon are perpendicular to each other - gravitational force is the weakest

22
Q

What is isostatic subsidence

A

When the ice km layer is thick the weight is heavy and therefore puts pressure on the mantle and crust. The mantle is a soft, viscous fluid so would push the land downward

23
Q

What is post-glacial adjustment? ( explained with Britain)

A

Britains north was glaciated and pushed down. Southern areas were ice free and tilted up. When the ice melts the land in the north rebound back and the sounthern areas tilts back down.

23
Q

What islands/coastal environments will disappear because of sea level rise

A

Low-lying islands such as the Maldives will disappear and coastal ecosystems such as the sundarbans in Bangladesh and India

23
Q

What is thermal expansion?

A

As seawater heats up by absorbing heat from the atmosphere, it’s volume expands.

23
Q

What does dominant wind mean?

A

Dominant wind is the direction of the strongest wind

23
Q

What is thermal expansion?

A

As the sea heats up, its volume increases.
Contributes to 50 percent of sea level rise.

24
Q

What percent of Egyptian people live near the nile delta

A

95%

25
Q

Name some examples of what is in the nile delta?

A

holiday beach resorts, tourism, settlements, agriculture,

25
Q

What does prevailing wind mean

A

Prevailing wind is the direction of the most common wind

25
Q

How does height increase the flood risk of coastlines?

A

Low lying coastlines are only 1-2 m high above (high tide) sea level so at risk from flooding

25
Q

Why is the rate of sea level rise increasing?

A

As the oceans warm and polar ice melting exceeds expected rates. A sea level rise of 2m by 2100 is predicted.

26
Q

What are raised cliffs?

A

Is a former beach now above the high tideline.
They contain different levels (different stage of uplift)
Rounded pebbles and boulders.

27
Q

What was the average rate of rising sea levels between 1993-2010

A

3.2mm a year

27
Q

How long is the coast of nile delta?

A

240km

28
Q

Why is there more coastal recession in winter?

A

The difference between the temp at the equator and the pole is greatest (great depression) - creates high windspeeds

28
Q

How has global warming contributed to increased rates of coastal recession?

A

More heat in the atmosphere, intensifying low-pressure systems.

Geography (8 decks)

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