1.2 Coastal landscapes and change Flashcards
1
Q
Is the coast and open or closed system? Why?
A
- The coast can be considered as an open system as it receives inputs from outside the system and transfers outputs away from the coast and into other systems.
- These systems may be terrestrial, atmospheric or oceanic and can include the rock, water and carbon cycles.
2
Q
Describe sediment cells (6)
A
- Coasts can be split into sections called sediment cells.
- a largely self-contained stretch of coastline
- typically considered a closed-system in terms of sediment.
- There are eleven sediment cells in England and Wales.
- Under normal conditions, the coastal system operates in a state of dynamic equilibrium.
- Sediment cells are not fully closed systems, so it is important to remember that actions within one cell may affect another.
3
Q
Define dynamic equilibrium
A
- Dynamic equilibrium in a sediment cell is where input and outputs of sediment are in a constant state of change but remain in balance.
- Physical and human action can change this equilibrium.
4
Q
Sources in sediment cells
A
– Where the sediment originates from (e.g. cliffs, offshore bars).
5
Q
Through flows in sediment cells
A
The movement of sediment along the shore through longshore drift.
6
Q
Sinks in sediment cells
A
Locations where deposition of sediment dominates (e.g. spits, beaches).
7
Q
Define negative feedback
A
- mechanisms which balances changes, taking the system back towards equilibrium
- this lessens any change which has occurred within the system
8
Q
Describe the negative feedback loop following a storm (5)
A
- a storm could erode a large amount of a beach, taking the beach out of dynamic equilibrium as there is a larger input of sediment than output
- When the destructive waves from the storm lose their energy excess sediment is deposited as an offshore bar.
- The bar dissipates the waves energy which protects the beach from further erosion.
- Over time the bar gets eroded instead of the beach.
- Once the bar has gone normal conditions ensue and the system goes back to dynamic equilibrium
9
Q
Define positive feedback
A
- mechanisms which enhance changes within a system, taking it away from dynamic equilibrium
- this exaggerates the change making the system more unstable
10
Q
Describe the positive feedback loop after sand dunes have been trampled (3)
A
- People walking over sand dunes destroys vegetation growing there and causes erosion.
- As the roots from the vegetation have been holding the sand dunes together, damaging the vegetation makes the sand dunes more susceptible to erosion. This increases the rate of erosion.
- Eventually the sand dunes will be completely eroded leaving more of the beach open to erosion taking the beach further away from dynamic equilibrium.
11
Q
Define littoral zone
A
The littoral zone is the area of the coast where land is subject to wave action.
12
Q
Factors affecting the littoral zone
A
- Short-term factors like tides and storm surges.
- Long-term factors like changes in sea level and climate change.
13
Q
Subzones of the littoral zone (4)
A
- Offshore
- Nearshore
- Foreshore
- Backshore
14
Q
Define offshore
A
- Where waves begin to break in the deeper water.
- Friction between the waves and the sea bed may cause some distortion of the wave shape.
15
Q
Define nearshore
A
- Friction between the seabed and waves distorts the wave sufficiently to cause it to break.
- Possible breakpoint bar formation.
16
Q
Define foreshore
A
- The area between the high tide and the low tide mark.
- this is land where most wave processes occur.
17
Q
Define backshore
A
The area above the high tide mark, affected by wave action only during major storm events.
18
Q
Describe valentine’s classification
A
- Valentine’s Classification describes the range of coastlines that can occur.
- An advancing coastline may be due to the land emerging or deposition being the prominent
process. - Alternatively, a coastline may be retreating due to the land submerging or erosion being the prominent process.
19
Q
Define emergent coastline
A
As Sea Levels fall, coastline land is exposed which was previously covered by the sea
20
Q
Describe a raised beach
A
- A raised beach is a former beach now above the high tideline.
- Some raised beaches may consist of several different levels, each indicating a different stage of uplift.
- Features such as rounded pebbles and boulders are likely to be present, but smaller particles have usually been removed.
21
Q
Describe a fossil cliff
A
- A fossil cliff is a near-vertical slope initially formed by marine processes but now some distance inland.
- Other coastal erosional features, such as sea caves and a wave-cut platform, may still be visible.
22
Q
Define submergent coastline
A
As Sea Levels rise, the land is covered
23
Q
Define a ria
A
- A ria is a flooded river valley.
- During an ice age some land areas were not covered with ice but had frozen ground, so rivers carved valleys with steeper sides than normal.
- Then, after the ice melted, sea levels rose and drowned the mouths of these valleys.
- e.g. Sydney Harbour, Australia
24
Q
Describe a fjord
A
- A fjord is a flooded glaciated valley.
- During an ice age, glaciers eroded U-shaped valleys down to the coast of the time and then, after the ice melted, the sea level rose again and flooded into the valley over a shallow threshold, creating a very deep water inlet with steep sides,
- All the features of a normal U-shaped valley are present, such as hanging valleys and truncated spurs.
25
Types of erosional processes (6)
- corrasion
- abrasion
- attrition
- hydraulic action
- corrosion (solution)
- wave quarrying
26
Describe corrasion
- Sand and pebbles are picked up by the sea from an offshore sediment sink or temporal store and hurled against the cliffs at high tide, causing the cliffs to be eroded.
- The shape, size, weight and quantity of sediment picked up, as well as the wave speed, affects the erosive power of this process.
27
Describe abrasion
This is the process where sediment is moved along the shoreline , causing it to be worn down over time .
28
Describe attrition
- Wave action cause rocks and pebbles to hit against each other , wearing each other down and so becoming round and eventually smaller.
- Attrition is an erosive process within the coastal environment, but has little to no effect on erosion of the coastline itself.
29
Describe hydraulic action
- As a wave crashes onto a rock or cliff face, air is forced into cracks, joints and faults within the rock.
- The high pressure causes the cracks to force apart and widen when the wave retreats and the air expands.
- Over time this causes the rock to fracture.
- Bubbles found within the water may implode under the high pressure creating tiny jets of water that over time erode the rock. This erosive process is cavitation
30
Describe corrosion (solution)
- The mildly acidic seawater can cause alkaline rock such as limestone to be eroded and is very similar to the process of carbonation weathering.
- This is a potential link between the carbon cycle, global warming and coasts.
31
Describe wave quarrying
- This is when breaking waves that hit the cliff face exert a pressure up to 30 tonnes per m ².
- It is very similar to hydraulic action but acts with significantly more pressure to directly pull away rocks from a cliff face or remove smaller weathered fragments.
- The force of the breaking wave hammers the rocks surface , shaking and weakening it and leaving it open to attack from hydraulic action and abrasion.
32
Erosion rates are highest when... (5)
- waves are high and have a long fetch (the distance the wind has travelled over the wave)
- waves approach the coast perpendicular to the cliff.
- at high tide - waves travel higher up the cliff so a bigger area of cliff face is able to be eroded.
- heavy rainfall occurs - water percolates through permeable rock, weakening cliff.
- in winter - destructive waves are the largest and most destructive during winter
33
Factors affecting the resistance of a rock (3)
- whether rocks are clastic or crystalline - crystalline rocks are more resistant to erosion
- The amount of cracks, fractures and fissures – the more weaknesses there are in the rock the more open it is to erosional processes, especially Hydraulic Action.
- The lithology of the rock (rock type)
34
Define clastic
rocks composed of broken pieces of older rocks.
35
Define crystalline
any rock composed entirely of crystallized minerals
36
Describe igneous rocks (3)
- e.g. Granite, Basalt
- Very slow erosion rate (<0.1cm/year)
- Interlocking crystals which allow for high resistance
37
Describe metamorphic rocks (3)
- e.g. Slate, Schist, Marble
- Slow erosion rate (0.1-0.3cm/year)
- Crystal all orientated in the same direction
38
Describe sedimentary rocks (3)
- e.g. Limestone
- Very fast erosion rate (0.5-10cm/year)
- Lots of fractures & bedding planes making them weak
39
Describe how caves, arches, stacks, & stumps are formed (4)
- Marine erosion widens faults in the base of the headland, widening over time to create a cave.
- The cave will widen due to both marine erosion and sub-aerial processes, eroding through to the other side of the headland, creating an arch.
- The arch continues to widen until it is unable to support itself, falling under its own weight through mass movement, leaving a stack as one side of the arch becomes detached from the mainland.
- With marine erosion attacking the base of the stack, eventually the stack will collapse into a stump.
40
Describe how a wave-cut notch and platform is formed (3)
- Marine erosion attacks the base of a cliff, creating a notch of eroded material between high tide height and low tide height.
- As the notch becomes deeper (and sub-aerial weathering weakens the cliff from the top) the cliff face becomes unstable and falls under its own weight through mass movement.
- This leaves behind a platform of the unaffected cliff base beneath the wave-cut notch.
41
Describe retreating cliffs
Through the process of repeat wave-cut notches and platforms, new cliff faces are created, whilst the land retreats
42
Describe a blowhole (4)
- A Blowhole is a combination of two features: a pot hole on top of a cliff, created by chemical weathering, and a cave, formed by marine erosion.
- As the cave erodes deeper into the cliff face and the pothole deepens, they may meet.
- a channel is created for incoming waves to travel into and up the cliff face
- occasionally water splashes out of the top of the blowhole when energetic waves hit the cliff face
43
Describe long shore drift (LSD) (4)
● Waves hit the beach at an angle determined by the direction of the prevailing wind.
● The waves push sediment in this direction and up the beach in the swash.
● Due to gravity, the wave then carries sediment back down the beach in the backwash.
● This moves sediment along the beach over time.
44
Processes of transportation (4)
- traction
- saltation
- suspension
- solution
45
Define traction
Large, heavy sediment rolls along the sea bed, being pushed by currents.
46
Define saltation
Smaller sediment bounces along the sea bed, being pushed by currents.
47
Define suspension
Small sediment is carried within the water column (a body of water)
48
Define solution
Dissolved material is carried within the water
49
Factors affecting the effectiveness of transportation
The impact of transportation depends on the severity of the angle that waves travel onto land.
50
Define drift-aligned
waves approach at a significant angle, so longshore drift causes the sediment to travel far up the beach.
51
Define swash-aligned
wave crests approach parallel to coast so there is limited longshore drift. Sediment doesn’t travel up the beach far.
52
When does deposition occur?
- Deposition occurs when a wave loses energy meaning the sediment becomes too heavy to carry.
- Deposition tends to be a gradual and continuous process - a wave won’t drop all of its sediment all at once.
53
Define gravity settling
the wave’s energy becomes very low and so heavy rocks and boulders are deposited followed by the next heaviest sediment.
54
Define flocculation
clay particles clump together due to chemical attraction and then sink due to their high density
55
Describe the formation of a spit (5)
- A spit is a long narrow strip of land which is formed due to deposition.
- Longshore drift occurs along the coast line but as the waves lose energy (normally due to going into a sheltered area such as behind a headland) they deposit their sediment. Over time this creates a spit.
- Periodically, the prevailing wind will change direction causing a hook to appear.
- the sheltered area behind a spit can turn into a salt marsh.
- The length of a spit is influenced by surrounding currents or rivers.
56
Describe a bar
A spit which, over time, crosses a bay and links up two sections of coast (the water within the bay is called a lagoon).
57
Describe the formation of a tombolo
- A tombolo is a bar or beach that connects the mainland to an offshore island and is formed due to wave refraction off the coastal island reducing wave velocity, leading to deposition of sediments.
- They may be covered at high tide if they are low lying.
58
Describe the formation of cuspate forelands
- Only occurs with triangular shaped headlands.
- Longshore drift along each side of the headland will create beaches, which where they meet, will form a cuspate foreland.
59
Describe the formation of offshore bars
- A region offshore where sand is deposited, as the waves don’t have enough energy to carry the sediment to shore.
- They can be formed as the wave breaks early, scouring the seabed and instantly depositing its sediment as a loose-sediment offshore bar.
60
Conditions required for sand dunes to form
- Sand dunes occur when prevailing winds blow sediment to the back of the beach and therefore the formation of dunes requires large quantities of sand and a large tidal range.
- This allows the sand to dry, so that it is light enough to be picked up and carried by the wind to the back of the beach.
- Frequent and strong onshore winds are also necessary
61
Embryo dune
Upper beach area where sand starts to accumulate around a small obstacle (driftwood, wooden peg, ridge of shingle)
62
Yellow dune
- As more sand accumulates and the dune grows, vegetation (marram grass) may develop on the upper and back dune surfaces, which stabilises the dune
- The tallest of the dune succession
63
Grey dune
Sand develops into soil with lots of moisture and nutrients, as vegetation dies, enabling more varied plant growth.
64
Describe a dune slack
The water table rises closer to the surface, or water is trapped between hollows between dunes during storms, allowing the development of moisture-loving plants (e.g. willow grass)
65
Climax community
Sandy soils develop as there is a greater nutrients content, allowing for less brackish plants to thrive. Trees will also grow (willow, birch, oak trees) with the coastal woodland becoming a natural windbreak to the mainland behind.
66
Describe the stability of depositional landforms (3)
- Depositional landforms consist of unconsolidated sediment and are therefore vulnerable to change.
- During major storms, large amounts of sediment can be eroded or transported elsewhere removing a landform from one region of the sediment cell.
- Depositional landforms depend on a continuous supply of sediment to balance erosion, which may see some landforms changed as their dynamic equilibrium shifts.
67
Define weathering
Weathering is the breakdown of rocks (mechanical, biological or chemical) over time, leading to the transfer of material into the littoral zone, where it becomes an input to sediment cells.
68
Define mechanical weathering
the breakdown of rocks due to exertion of physical forces without any chemical changes taking place
69
Examples of mechanical weathering (3)
- freeze-thaw
- salt crystallisation
- wetting and drying
70
Describe freeze-thaw weathering
- Water enters cracks in rocks and then the water freezes overnight during the winter.
- As it freezes, water expands by around 10% in volume which increases the pressure acting on a rock, causing cracks to develop.
- Over time these cracks grow, weakening the cliff making is more vulnerable to other processes of erosion
71
Describe salt crystallisation weathering
- As seawater evaporates, salt is left behind.
- Salt crystals will grow over time, exerting pressure on the rock, which forces the cracks to widen.
- Salt can also corrode ferrous (materials that contains iron) rock due to chemical reactions
72
Describe wetting and drying weathering
- Rocks such as clay expand when wet and then contract again when they are drying.
- The frequent cycles of wetting and drying at the coast can cause these rocks and cliffs to break up
73
Define chemical weathering
the breakdown of rocks through chemical reactions.
74
Examples of chemical weathering (3)
- carbonation
- oxidation
- solution
75
describe carbonation
- Rainwater absorbs CO2 from the air to create a weak carbonic acid which then reacts with calcium carbonate in rocks to form calcium bicarbonate which can then be easily dissolved.
- Acid rain reacts with limestone to form calcium bicarbonate, which is then easily dissolved allowing erosion.
76
Describe oxidation
- When minerals become exposed to the air through cracks and fissures , the mineral will become oxidised which will increase its volume (contributing to mechanical weathering), causing the rock to crumble.
- The most common oxidation within rocks is iron minerals becoming iron oxide, turning the rock rusty orange after being exposed to the air.
77
Describe solution (weathering)
When rock minerals such as rock salt are dissolved.
78
Define biological weathering
- the breakdown of rocks due to the actions of plants, bacteria and animals
79
Examples of biological weathering (5)
- plant roots
- birds
- rock boring
- seaweed acids
- decaying vegetation
80
Describe how plant roots cause weathering
Roots of plants growing into the cracks of rocks, which exerts pressure, eventually splitting the rocks
81
Describe how birds cause weathering
Some birds such as Puffins dig burrows into cliffs weakening them and making erosion more likely.
82
Describe how rock boring causes weathering
Many species of clams secrete chemicals that dissolve rocks and piddocks may burrow into the rock face
83
Describe how seaweed acids cause weathering
Some seaweeds contain pockets of sulphuric acid, which if hit against a rock or cliff face, the acid will dissolve some of the rock’s minerals. (e.g. Kelp)
84
Describe how decaying vegetation causes weathering
Water that flows through decaying vegetation and then over coastal areas, will be acidic, thus causing chemical weathering
85
Define mass movement
the downhill movement of material under the force of gravity
86
the type of mass movement that occurs depends on... (4)
- the angle of the slope/cliff
- the rock’s lithology and geology
- the vegetation cover on the cliff face
- the saturation of the ground/ previous weather patterns
87
What is the difference between a slide and a flow?
- For a slide, sediment keeps its same place within the whole material, simply moves downhill.
- However, for a flow, all the material flows downs and mixes.
88
Examples of flows (3)
- soil creep
- solifluction
- mudflows
89
Describe a soil creep
The slowest but continuous form of mass movement involving the movement of soil particles downhill.
90
Describe a solifluction
- Occurs mainly in tundra areas where the land is frozen.
- As the top layers thaws during summer (but the lower layers still stay frozen due to permafrost) the surface layers flows over the frozen layers.
91
Describe a mudflow
An increase in the water content of soil can reduce friction, leading to earth and mud to flow over underlying bedrock
92
Examples of slides (3)
- rock falls
- rock slides
- slumps
93
Describe a rock fall
Occur on sloped cliffs (over 40o ) when exposed to mechanical weathering.
94
Describe rock slides
Water between joints and bedding planes (which are parallel to the cliff face) can reduce friction and lead to more sliding.
95
Describe slumps
Occur when the soil is saturated with water, causing a rotation movement of soft materials (such as clay and sand) forming rotational scars and terraced cliff profiles.
96
Factors increasing vulnerability to sub-aerial processes
- Temperature and climate can influence the prominent process of weathering.
- In colder climates, mechanical weathering is more common
- in warmer climates, chemical weathering is more common.
97
Factors influencing cliff profiles (2)
- The resistance of the rock to erosion
- The dip in rock strata in relation to the sea
98
Describe a concordant coastline
- Concordant coastlines are where the rock strata run parallel to the coast.
- The rock type varies between different concordant coasts and normally consist of bands of more resistant and less resistant rock.
- For example, limestone may run in parallel bands with clays and sands.
- These different rock types create different landforms due to erosion
99
Describe a dalmatian coastline
- Concordant coastlines can lead to the formation of Dalmatian coastlines
- a rise in sea levels leads to the flooded widen river valleys between tall headlands.
- The headlands become islands, running perpendicular to the mainland
100
Describe haff coasts
Haff coasts are also dependant on a concordant coastline, where large bays are crossed by spits, creating a extensive lagoons.
101
Describe a discordant coastline
This is where the rock strata run perpendicular to the sea, which can create successions of headlands and bays; less resistant rocks are eroded faster than the more resistant rocks, which leads to the formation of bays
102
Describe the process of wave refraction
- Wave refraction is the process by which waves turn and lose energy around a headland on uneven coastlines.
- The wave energy is focussed on the headlands, creating erosive features in these areas.
- The energy is dissipated in bays leading to the formation of features associated with lower energy environments such as beaches.
103
How does vegetation help stabilise coastal sediment? (3)
▪ Roots of plants bind soil together which helps to reduce erosion.
▪ When completely submerged, plants provide a protective layer for the ground and so the ground is less easily eroded.
▪ Plants reduce the wind speed at the surface and so less wind erosion occurs
104
Define xerophyte
plants that are tolerant of dry conditions.
105
Define halophyte
plants that are tolerant of salty conditions
106
Describe the process of plant succession
- Plant succession is a long-term change in a plant community in an area.
- On coasts where there is a supply of sediment and deposition occurs, pioneer plants begin to grow in bare mud and sand. Due to the salty soil conditions only certain plants can grow there.
- As more deposition occurs and the vegetation dies and releases nutrients into the sand this reduces the saltiness of the soil which means different plants can start growing there.
- These processes continue over time allowing new species of plants to colonise.
107
How is marram grass adapted to be a good pioneer plant? (3)
- it is tough and flexible, so can cope when being blasted with sand.
- it has adapted to reduce water loss through transpiration.
- Their roots grow up to 3 metres deep and can tolerate temperatures of up to 60oC
108
Stages of salt marsh succession (5)
- algal stage
- pioneer stage
- establishment stage
- stabilisation
- climax vegetation
109
Why are estuarine areas ideal for salt marshes?
- they're sheltered from strong waves (so sediment like mud and silt can be deposited)
- rivers transport a supply of sediment to the river mouth, which may be added to by sediment flowing into the estuary at high tide
110
Describe the stages of salt marsh formation (6)
- mixing of fresh water and sea water causes clay particles to stick together and sink (flocculation)
- Blue-green algae and gut weed colonise mud, exposed at low tide for only a few hours.
- The algae binds mud, adds organic matter, and traps sediment.
- As the sediment thickens, water depth is reduced, and the mud is covered by tide for less time.
- Halophytic glasswort and cord grass colonise - the marsh is still low, and covered by high tide each day.
- An accumulation of organic matter and sediment raises the height of the marsh until it is only covered by spring tides.
111
Describe the late stages of salt marsh succession (climax community)
- The higher marsh is colonised by less hardy plants: sea aster, sea lavender, sea thrift, scurvy grass
- Rainwater washes salt out of the high marsh's soil, allowing land plants to colonise.
- This continues until climax community is reached.
- In most of the UK, the climax community would be deciduous oak forest, or coniferous pine forest in north Scotland.
112
Describe a high energy coastline
- High-energy coastlines are associated with more powerful waves, so occur in areas where there is a large fetch.
- They typically have rocky headlands and landforms and fairly frequent destructive waves.
- As a result these coastlines are often eroding as the rate of erosion exceeds the rate of deposition
113
Describe a low energy coastline
- Low-energy coastlines have less powerful waves and occur in sheltered areas where constructive waves prevail and as a result these are often fairly sandy areas .
- There are landforms of deposition as the rates of deposition exceed the rates of erosion.
114
Factors affecting the size of waves (4)
- The strength of the wind
- How long the wind has been blowing for
- Water depth
- Distance of fetch
115
features of constructive waves (4)
▪ Strong swash, weak backwash
▪ Low wave height, long wavelength
▪ Low frequency
▪ Depositional
116
features of destructive waves (4)
▪ Strong backwash, weak swash
▪ High wave height, short wavelength
▪ High frequency
▪ Erosional
117
Reasons why the wave types hitting a beach may vary over time (5)
● In summer, constructive waves dominate but destructive waves dominate in winter.
● Constructive waves may turn into destructive waves as a storm begins.
● Climate change could mean that the UK may become more stormier meaning an increase in destructive waves.
● Dams prevent sediment being transported from rivers and entering into the coastal area which means erosion could increase.
● Interference with natural processes along the coast (e.g. through human activity) could affect sediment supply across a coastal area.
118
Reasons for short-term sea level change (3)
- High tide and low tide - a daily phenomena due to the gravitational pull of the Moon
- Wind strength and direction - these can change causing a change in sea level for a couple of minutes or longer
- Atmospheric pressure - the lower the pressure, the higher the sea levels.
119
Describe isostatic change
- localised sea level change
- could be due to post-glacial adjustment (glaciers weigh down the land beneath, and so the land subsides until it melts).
- Tectonic activity may cause land subsidence
120
Describe eustatic change
- Global sea level change
- Eustatic rise is due to thermal expansion. Water expands when it gets warmer, and so the volume of water increases which as a result, sea levels increase. This is due to Global Warming.
- global warming also melts sea ice, increasing the volume of water in oceans
- predicting sea level change is very difficult because various factors could affect changes, and the cause isn’t still fully understood.
121
Describe coastalisation
- Coastalisation is the movement of people towards the coast.
- Despite having a high flood risk, may people move to the coast due to tourism, high-yield agricultural lands, or housing pressure.
- Coastalisation can increase the environmental vulnerability of these locals to flooding due to storm surges
122
Define a storm surge
A storm surge occurs when there is a short-term change in sea level, which may be due to low pressure during a depression or tropical cyclone
123
Factors that can exacerbate storm surges (3)
● Subsidence of the land - through tectonic activity or post-glacial adjustment.
● Removing natural vegetation - Mangrove forests are the most productive and complex ecosystem in the world and provide protection against extreme weather events. However, due to pressure for land space, mangrove forests are destroyed for tourism, local industry, or housing plains.
● Global Warming - As the surface of oceans get warmer, it is estimated that the frequency and intensity of storms will increase, and so the severity of storm surges and flooding is also expected to increase.
124
consequences of storm surges for communities (5)
- Some areas of the coast may have significantly reduced house and land prices, which can lead to economic loss for homeowners and local coastal economies.
- In the UK, many insurers don’t provide home insurance to people living along coastlines that are at extreme risk of erosion or storm surges.
- Storm surges also damage the environment by destroying plant successions
- Depositional landforms, due to their unconsolidated nature, are likely to be destroyed.
- erosion may take place at accelerated rates or higher up along the cliff face, which can increase the risk of collapse.
125
Why might there be an increase in environmental refugees?
- Globally, more than 1 billion people live on coasts that are at risk from coastal flooding
- 50% of the world’s population currently live within 200km of the coast.
- As storm surges and erosion along some coastlines are predicted to increase, so too is the volume of environmental refugees displaced internally or internationally.
- People may lose their homes, way of life and culture as they are forced to migrate to avoid the rising eustatic sea level and the rising risk of coastal flooding.
126
Different approaches to managing coastal areas (4)
● Hold the line – Defences are built to try and keep the shore where it is.
● Managed realignment – Coastline moves inland naturally but managed.
● Advance the line – Defence are built to try and move the shore seawards.
● Do nothing – No defences are put in place and the coast is allowed to erode.
127
Factors considered when deciding on a coastal management approach (3)
▪ Economic value of assets that could be protected is looked at
▪ The technical feasibility of engineering solutions, for example a sea wall may not be possible for a certain location.
▪ The ecological and cultural value of land. For example, it may be desirable to protect historic sites or SSSI.
128
Describe a cost-benefit analysis (CBA)
- This is an analysis that is carried out before any form of coastal management takes place.
- The cost involved include construction, demolition, maintenance etc. is then compared to the expected benefits like the value of land saved, homes and businesses protected.
- Costs and benefits include both tangible and intangible things.
- For a project to be given the go ahead, the expected benefits have to outweigh the costs
129
Describe Integrated Coastal Zone Management (4)
- A coastal area (sediment cell) is managed as a whole. This often involves management between different political boundaries
- The ICZM recognises the importance of the coast for people’s livelihoods.
- The ICZM recognises that coastal management must be sustainable whereby economic development is important but this should come at a cost for the environment.
- The ICZM must involve all stakeholders, plan for the long term and try to work with natural processes and not against them.
130
Describe shoreline management plans (SMPs)
- For each sediment cell in the UK, an SMP has been created to help with coastline management.
- Each SMP identifies all of the activities, both natural and human which occur within the coastline area of each sediment cell.
- The sediment cells are considered to be closed for the purposes of management, although in reality there will be some exchanges between the different cells.
- SMP’s are recommended for all sections of English and Welsh coastlines by DEFRA (governing body responsible for majority of environmental protection in the UK).
- Four options are considered for each stretch of the coastline
131
Describe hard engineering
- Hard engineering is a very traditional and somewhat outdated approach to coastal management and it involves man made structures that aim to prevent erosion
- They are often very effective at preventing erosion in the desired area, but are high cost and have a significant environmental impact due to the use of concrete and other man-made materials.
- By reducing erosion in one area of the coastline, they may act to exacerbate erosion elsewhere. - Therefore their only impact is to change where erosion is occuring.
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Examples of hard engineering (5)
- offshore breakwater
- groynes
- sea walls
- rip-rap (rock armour)
- revetments
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Offshore breakwater - description
Rock barrier which forces waves to break before reaching the shore
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Offshore breakwater - benefit
Effective at reducing waves’ energy
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Offshore breakwater - costs (3)
- Visually unappealling
- Navigation hazard for boats
- Can interfere with LSD
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Groynes - description
Timber or rock protrusions that trap sediment from LSD
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Groynes - benefits (2)
- Builds up beach, protecting cliff and increasing tourist potential
- Cost effective
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Groynes - costs (2)
- Visually unappealling
- Deprives areas downwind of sediment, increasing erosion elsewhere
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Sea walls - description
Concrete structures that absorb and reflect wave energy, with curved surface
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Sea walls - benefits (2)
- Effective erosion prevention
- Promenade has tourism benefits
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Sea walls - costs (3)
- Visually unappealling
- Expensive to construct and maintain
- Wave energy reflected elsewhere,
with impacts on erosion rates
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Rip rap - description
Large rocks that reduce wave energy, but allow water to flow through
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RIp rap - benefit
cost effective
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rip rap - costs (2)
- Rocks are sourced from elsewhere, so do not fit with local geology
- Pose a hazard if climbed upon
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Revetments - description
Wooden or concrete ramps that help absorb wave energy
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Revetments - benefit
cost effective
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Revetment - costs (2)
- Visually unappealling
- Can need constant maintenance, which creates an additional cost
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Describe soft engineering
- soft engineering aims to work with and complement the physical environment by using natural methods of coastal defence.
- They are useful for protecting against sea-level change as well as coastal erosion.
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Examples of soft-engineering (4)
- beach nourishment
- cliff regrading and drainage
- dune stabilisation
- marsh creation
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beach nourishment - description
Sediment is taken from offshore sources to build up the existing beach
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beach nourishment - benefits (2)
- Builds up beach, protecting cliff and increasing tourist potential
- Cost effective and looks natural
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beach nourishment - costs (2)
- Needs constant maintenance
- Dredging may have consequences on local coastal habitats
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Cliff regrading and drainage - description
Reduces the angle of the cliff to help stabilise it. A steeper cliff would be more likely to collapse
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Cliff regrading - benefits
cost effective
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cliff regrading - costs (2)
- Cliff may collapse suddenly as the cliff is drier leading to rock falls which pose a hazard
- May look unnatural
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dune stabilisation - description
Marram grass planted. The roots help bind the dunes, protecting land behind
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Dune stabilisation - benefits (2)
- Cost effective
- creates an important wildlife habitat
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Dune stabilisation - costs (2)
- Planting is time consuming
- lag time between planting and effectiveness (marram needs to grow)
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marsh creation - description
Type of managed retreat allowing low-lying areas to flood
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marsh creation - benefit
- Creates an important wildlife habitat
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marsh creation - cost
- Farmers lose land and may need
compensation as a result
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Aspects of sustainable coastal management (5)
- Managing natural resources like fish, water, farmland to ensure long-term productivity.
- Creating alternative livelihoods before people lose their existing jobs.
- Educating communities about the need and how to adapt.
- Monitoring coastal changes and then adapting or mitigating.
- Managing flood risk or relocating if needed.
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Who are the winners from coastal management?
- those who benefit economically (e.g. their homes and businesses are protected)
- environmentally (e.g. habitats are protected)
- socially (community ties still remain in place, people still have jobs so less stress and worrying).
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Who are the losers from coastal management?
- those who lose their property, lose a job, or have to relocate elsewhere.
- Communities and homeowners have a strong attachment to a place so losing their properties and their social networks is a great loss.
- This will make them financially worse off and many people may feel lonely if forced to move and may be angered if areas are not chosen to be protected.
- Business owners may be angered if nothing is done to protect the area in which they have their business, which could cause them to lose profitability and regular clients.
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Arguments that support the no active intervention approach (2)
● Coastal managers produce SMP for an entire area so they have to see what kind of impacts other may have if the coast is managed in one specific area
● Local authorities and DEFRA have had their budgets reduced as central government funding since 2010 has dropped and so they cannot invest in coastal management in all areas, they have to prioritise their funding to the most important places
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Impact of coastal management on sediment cells
- Installing a sea wall would reflect wave energy downdrift increasing wave energy and erosion elsewhere on the coastline.
- Less erosion occurs in these areas with the sea wall , so there is also less sediment in the areas with increased wave energy .
- Less sediment reduces the beach size , so the cliff is more exposed to erosion from the higher energy waves.
- Building groynes has the same effect on downdrift areas as longshore drift can no longer transport sediment away from one stretch of coastline.
