coats Pt2 Flashcards
Hard Engineering
Man-made structures built to control the flow of the sea and reduce flooding and erosion
Types of Hard Engineering
Sea wall
Rock Armour
Groynes
Gabions
Sea Wall
A wall made out of a hard material like concrete that reflects waves back to sea
Benefits of a sea wall
It prevents erosion of the coast. it also acts as a barrier to prevent flooding
costs of a sea wall
It creates a strong backwash that erodes under the wall. expensive to build and maintain
Gabions
A wall of wire cages filled with rocks, usually built at the foot of cliffs
benefits of Gabions
Gabions absorb wave energy and so reduce erosion. they are cheap and easy to build
Costs of Gabions
They’re ugly to look at and the wire cages can corrode over time
Rock armor
Boulders that are piled up along the coast.( it is also sometimes called rip-rap)
Benefits of Rock Armour
it absorbs wave energy, reducing erosion and flooding. it is a fairly cheap defense
Costs of Rock Armour
Boulders can be moved around by strong waves, so they need to be replaced
Groynes
Wooden or stone fences are built at right angles to the coast. They trap material transported by longshore drift
Benefits of Groynes
They create wider beaches that slow the waves. this gives greater protection from flooding and erosion. they are a fairly cheap defence
Costs of Groynes
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
Types of soft engineering
beach nourishment and reprofiling
Dune regeneration
Beach Nourishment and reprofiling
Sand and shingle from elsewhere (e.g. from sea bed) or from lower the beach that’s added to the upper part of beaches
benefits of Beach Nourishment and reprofiling
it creates wider beaches which slow the waves. this gives greater protection from flooding and erosion
cost of Beach Nourishment and Reprofiling
Taking material from the sea bed can kill organisms like sponges and corals. it’s a very expensive defence. it has to be repeated
Dune Regenerations
creating or restoring sand dunes by nourishment, or by planting vegetation to stabilize the sand
Benefits of Dune Regeneration
Dunes Create a barrier between land and sea and absorb wave energy, preventing flooding and erosion. stabilization is cheap
Costs of Dune Regeneration
The protection is limited to a small area. Nourishment is very expensive
Describe how a wave-cut platform is formed?
The sea attacks the base of the cliff-forming a wave-cut notch.
The notch increases in size causing the cliff to collapse.
The backwash carries the rubble towards the sea forming a wave-cut platform.
The process repeats and the cliff continues to retreat.
How is a bar formed?
Longshore drift carries sediment along from a headland, depositing sediment further out from the headland. Over time, this line of sediment joins two headlands together; a bar is formed, cutting the bay off from the sea.
describe longshore drift
- Waves approach the beach at an angle
- As waves break the swash carries material up the beach at the same angle
- The backwash carries material straight back down the beach under gravity
- This causes the material to move along the beach in a zig-zag pattern
- define and describe beaches
beaches are deposits of sand and shingle
sandy beaches are mainly found in sheltered bays and are created by constructive waves along high energy coasts sand is washed aqay leaving behind a pebble beach
- formation of sand dunes
at the back of the beach, sand blown inland can build up to form dunes
embryo dunes form around obstacles dunes develop and are stabilised by vegitation to form fore dunes and tall yellow dunes decomposing vegetation makes sand more fertile and a wider range of plants colonise the back dunes ponds can form in depressions
- what factors influence coastal landforms
Rock type- some rocks are together and more resistant to erosion than others. softer rocks are more easily eroded
geological structure- includes the way that rock has been folded or tilted. faults form lines of weakness
- swanage dorset
swanage lies on the south coast of england, the surrounding coastline has a range of coastal erosion and deposition landforms influenced by different rock types and geological structure. Rocks have been folded and tilted so that different rock types reach the coast
- poole harbour
one of the UK’s largest natural harbours. two spits have formed at the mouth
- Concordant coast line forms
where different rock types run parallel to the coast, so the coast is mainly formed of one type
- discordant coastline forms
where there are alternating bands of harder rock and softer rocks. this creates headlands and bays.
- define Medmerry
the flat, low lying land at medmerry, near chichester in southern england, is mainly used for farming and caravan parks. In the past, it was protected by a low sea wall.
the land is of relatively low value, so the sea was allowed to breach the sea wall in 2013 and flood some of the farmland
- describe medmerry managed retreat
costing £28 million, this managed retreat scheme will:
create a large natural saltmarsh helpt to protect surrounding farmland and caravan parks from flooding establish a wildlife habitat and encourage visitors to the area embankments have been built inland to protect farmland, roads and settlement. atteration of the coastline like this is called coastal realignment
- where is lyme regis
lyme regis is a small coastal town in Dorset, on englands south coast, and is popular with tourists
- what are the issues at lyne regis
unstable cliff
powerful waves from the south west cause rapid erosion foreshore erosion has destroyed or damaged many properties sea walls have been breached many times
- how has the lyme regis coastline been managed
the lyme regis environmental improvement scheme was set up in the early 1990s to provide long term coastal protection and reduce the threat of landslips. Engineering works were completed in 2015
- what are the key features of the lyme regis scheme
new sea wall and promenades
cliffs established creation of wide sand and shingle beacj to absorb wave energy extension of rock armour to absorb wave energy and retain beach new sea wall for extra protection cliffs stabilised to protect homes the total costs will be over £43 million
- lyme regis positive outcomes
new beaches have increased visitor numbers and seafront businesses are doing well
new defences have withstood stormy winters harbour is better protected
- Lyme Regis negative outcomes
increased visitor numbers have caused conflict due to traffic congestion and litter. some think the new defences spoil the landscape.
the new sea wall might interfere with natural processes and cause problems elsewhere
