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Geography > Coasts 2 > Flashcards

Coasts 2 Flashcards

Coastal protection, Lyme Regis.

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1
Q

What are examples of hard engineering working as coastal defences?

A

-Sea walls
-Groynes
-Gabions
-Rock armour

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2
Q

Hard engineering

A

Man made structures built to control the flow of the sea, and to reduce flooding and erosion.

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3
Q

Sea wall

A

A wall made out of hard material like concrete that absorbs wave energy and refracts it back out to the sea.

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4
Q

Sea wall advantages

A

-Highly effective in preventing erosion of the coast

-Long lasting >50yrs

-Acts as a barrier to prevent flooding

-Sense of security for community

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5
Q

Sea wall disadvantages

A

-Often made from concrete, which is not environmentally friendly as production releases CO₂

-Expensive to build and maintain

-Creates a strong backwash which erodes under the wall

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6
Q

What are the two types of sea wall?

A

-Traditional
-Recurved

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7
Q

What is the difference between traditional and recurved sea walls?

A

Traditional sea walls absorb the energy of waves, and are just built thicker if not strong enough.

On the other hand, recurved sea walls absorb energy but also refract waves back out to sea.

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8
Q

Groynes

A

Timber or rock structures built at right angles to the coast to trap material transported by longshore drift.

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9
Q

Groynes advantages

A

-A fairly cheap defence

-Create wider beaches which slow the waves, giving greater protection from erosion and flooding, and which are attractive to tourists.

-Can last for up to 40yrs if maintained well

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10
Q

Groynes disadvantages

A

-They starve beaches further down the coast of sand, making them narrower

-Narrow beaches don’t protect the coast as well, leading to greater erosion

-Unnatural

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11
Q

Gabions

A

A wall of wire cages filled with pebbles/rocks, usually built at the foot of cliffs.

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12
Q

Gabions advantages

A

-Absorb wave energy, and so reduce erosion

-Cheap and easy to build

-Can last for 20-30 yrs if well maintained

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13
Q

Gabions disadvantages

A

-Visually unappealing

-Can be damaged in just a few years if poor quality, or in heavy storms and become hazardous

-The wire cages can corrode over time

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14
Q

Rock armour

A

-Boulders of resistant rock that are piled up along the coast, forcing the waves to break, and dissipating the wave energy before it reaches the cliff behind.

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15
Q

Rock armour advantages

A

-Reduces erosion and flooding

-A relatively cheap defence

-Easy to maintain

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16
Q

Rock armour disadvantages

A

-Heavy so must be transported by a barge or helicopter to the coast

-Expensive if the rock cannot be sourced locally

-Ugly if rock doesn’t match the local geology

-If the boulders are too small they can be shifted around by strong waves, making the defence redundant.

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17
Q

What are examples of soft engineering working as coastal defences?

A

-Beach nourishment and Reprofiling

-Dune regeneration

(-managed retreat)

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18
Q

Soft engineering

A

Schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion.

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19
Q

Beach nourishment and Reprofiling

A

Sand and shingle from elsewhere (e.g. the seabed or lower down the beach) is added to the upper part of beaches.

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20
Q

Beach nourishment and reprofiling advantages

A

-Create wider beaches which slow the waves, giving greater protection from erosion and flooding, and which are attractive to tourists.

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21
Q

Beach nourishment and reprofiling disadvantages

A

-Taking material from the seabed can kill organisms like sponges and corals

-A very expensive defence

-Has to be repeated

22
Q

Dune regeneration

A

Creating or restoring sand dunes by nourishment, or by planting vegetation to stabilise the land.

23
Q

Dune regeneration advantages

A

-Dunes create a barrier between land and sea, and absorb wave energy, preventing flooding and erosion

-Stabilisation is cheap

24
Q

Dune regeneration disadvantages

A

-The protection is limited to a small area

-Nourishment is very expensive

25
Q

Managed retreat

A

Doing nothing!

Involves removing current defences and allowing the sea to flood the land behind.

Over time, the land will become marshland, protecting the land behind it from flooding and erosion.

26
Q

Managed retreat advantages

A

-A cheap and easy strategy

-Doesn’t need maintaining

-The marshland can create new habitats for plants and animals

27
Q

Managed retreat disadvantages

A

-Can cause conflicts (e.g…)

-Flooding farmland effects the livelihood of farmers; saltwater can have a negative effect on existing ecosystems

28
Q

Managed retreat example

A

Was carried out at Alkborough Flats, Lincolnshire.

A 20m wide breach was made in the flood wall to allow water to flow inland.

This area provides a habitat for many bird and fish species.

It helps protect 400,000 homes from floods.

29
Q

What is our example of a coastal management scheme in the UK?

A

The scheme at Lyme Regis

30
Q

Cliffs of Lyme Regis

A

-Powerful waves from the south west are eroding the sea cliffs at Lyme Regis, causing them to collapse.

-Much of the town’s eastern side is built along the very edge of the cliffs, and many properties have been damaged by landslides, slumps, and waves breaching sea walls.

31
Q

What are the reasons for the management of Lyme Regis?

A

-The town has a population of over 3600 people, and around 500,000 tourist visits each year

-Around 900m of the A3052 road (linking Lyme Regis to other towns along the coast) would’ve been lost within 50 years

32
Q

The local economy (Lyme Regis) depends on what?

A

Tourism.

But, erosion of the coast could threaten the historic town centre and tourism industry.

33
Q

How much money was spent by tourists at Lyme Regis in 2015?

A

About £42 million

34
Q

How is (about 1km of) the coastline managed at Lyme Regis?

A

Using hard engineering strategies.

35
Q

Outline the management strategy at Lyme Regis.

A

Parts of the town are protected by Sea Walls and Rock Armour.

36
Q

When did the management scheme to provide long-term protection for Lyme Regis begin? Why whom?

A

The 1990s

West Dorset District Council

37
Q

When was phase 1 of the management strategy at Lyme Regis completed?

A

1995

38
Q

What did phase 1of the management strategy at Lyme Regis involve?

A

Building new rock armour on the eastern end of the sea front.

39
Q

What did phase 2 of the management strategy at Lyme Regis involve?

A

-Replenishing and stabilising the sand and shingle beaches

-Extending the existing rock armour (Beacon rocks) and realigned (North Wall Rockery)

-Improving drainage systems

40
Q

Why were drainage systems at Lyme Regis improved?

A

To reduce water build up and prevent landslides.

41
Q

When was phase 2 of the management strategy at Lyme Regis completed?

A

2007

42
Q

How much did phase 2 of the management strategy at Lyme Regis cost?

A

£26 million

43
Q

What was phase 3 of the management strategy at Lyme Regis?

A

It was meant to prevent landslides to the west of Lyme Regis but was never carried out.

It wasn’t worth the high cost.

44
Q

When was phase 4 of the management strategy at Lyme Regis completed?

A

2015

45
Q

How much did phase 4 of the management strategy at Lyme Regis cost?

A

£19.5 million

46
Q

What did phase 4 of the management strategy at Lyme Regis include?

A

-390m of sea walls and rock armour

-Protecting roads into the town

47
Q

What is Lyme Regis?

A

A historic town in Dorset, southwest England.

The coastline has been managed there for many years.

48
Q

Positive effect of the management strategy at Lyme Regis .

A

-It is thought that the improved beaches have increased trade by up to 20% in some parts of the town.

-The rock armour absorbs the energy of the powerful waves, protecting the harbour and the boats inside.

-People feel more secure buying property in the town

49
Q

Why might people feel more secure buying property in Lyme Regis?

A

The new defences have made it easier to insure houses against coastal erosion and landslides.

50
Q

Resulting conflicts of the management strategy at Lyme Regis.

A

-Greater numbers of tourists mean that there’s more traffic, litter, and noise pollution.

-Important fossils have been found in the area, but the defences stop new fossils from being discovered.

-Some residents think that the management scheme was very expensive for a relatively short-term solution; the defences could need rebuilding in around 60 years’ time.

Geography (18 decks)

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