❌Paper 1 - Section B - Coastal Landscapes and Change Flashcards
1
Q
Define littoral zone
A
Wider coastal zone including nearby land and shallow parts of sea offshore.
It constantly changes as it is subject to wave action — short and long term factors i.e., tides, climate change
2
Q
What is a sub-zone, and name the 4
A
A sub-zone is a smaller section within the littoral zone.
Starting from furthest inland outwards:
- Back shore:
Only affected by waves during major storms and spring tides - Foreshore:
Part of shore between high and low tide watermarks - Nearshore:
Shallow waters nearest the land - Offshore:
The open sea
3
Q
What are the 4 coastal inputs, -> 5 geomorphic processes, -> 3 outputs
A
Inputs:
- Marine I.e waves, tides
- Atmospheric i.e weather, climate change
- Land I.e rock type, tectonic activity
- People I.e human activity, coastal management
Processes:
- Weathering
- Mass movement
- Erosion
- Transport
- Deposition
Outputs:
- Erosional landforms
- Depositional landforms
- Different types of coasts
4
Q
What is a littoral cell
A
Self contained section of coast. Sediment within the cell is only circulated within that cell and doesn’t affect neighbouring sections
5
Q
By what characteristics can coasts be classified?
A
- Their geology
Rock content, concordant discordant etc - Their level of energy
High or low - Balance between erosion and deposition
Either Erosional or depositional features - Changes in sea level
Emergent or submergent coasts
6
Q
Describe a concordant coastline
A
beds or layers of differing rock type are folded into ridges that run PARALLEL to the coast
7
Q
Describe a discordant coast
A
Bands of differing rock type run PERPENDICULAR to the coast
8
Q
What are the 3 rock types?
A
- Igneous
Formed from cooling magma - Sedimentary
Rocks Changed by heat or pressure - Metamorphic
Made when eroded material is laid down in layers
9
Q
What is valentines coasts classification?
1952
A
It describes the range of coastlines that can occur.
An advancing coastline may be due to land emerging or deposition
A retreating coastline may be due to land submerging or erosion
Emergent or submergent coasts may be due to post-glacial adjustment (land ‘wobbles’ as glacier above melts): ISOSTATIC SEA-LEVEL CHANGE
10
Q
Name 5 rock geological features that can occur on cliff profiles and what they are (think strata, cracks etc)
A
-
Joints
Vertical cracks caused by contraction as sediment drys out -
Dip
Angle at which rock strata lies (horizontal, vertical, dipping inland etc) -
Folds
Formed by pressure during tectonic activity, makes rocks crumple -
Bedding planes
Horizontal cracks, natural breaks in strata caused by gaps in time during rock formation periods -
Strata
Layers of rock
11
Q
What factors determine morphology of coastline? (Think in terms of the rock)
A
- lithology of rock
- relief and slope (cliff profiles)
- rock type (sedimentary, igneous etc)
- permeability of rock
- hardness of rock, it’s resistance to erosion
12
Q
What is mechanical / physical weathering? (Describe our 3 examples)
A
Breakdown of rocks into fragments
May be caused by freeze-thaw shattering, salt crystallisation, wetting and drying etc
FREEZE THAW: water gets into rock cracks and freezes — expands water by 10%. Repeated action puts pressure on rocks til they crack.
WETTING AND DRYING: clay rich rocks expand when wet, contract when dry — cracks
SALT CRYSTALLISATION: salt crystals deposited into cracks, over time salt accumulates and applies pressure to cracks
Shards (scree) gather at bottom of cliffs
13
Q
What is biological weathering?
A
Mechanical when there is a physical effect
I.e plants growing roots — widens cracks.
Burrowing animals erodes cliff material
14
Q
What is chemical weathering?
A
Involves decomposition of rocks (changing of minerals) as a result of weak chemical reaction between rock and water i.e limestone
15
Q
Mass movement: what are flows? (And 3 types)
A
Flows: occur when fine grained sediment I.e silt and clay mix with water and lose their cohesion: flow downhill from gravity
- Soil creep: individual soil particles move downhill (slow but continuous)
-
Solifluction: (tundra) top layer of soil thaws in warmer summers but below layer remains frozen: PERMAFROST.
Surface layer flows over subsoil and rock below (5cm to 1m per year) - Mudflow: heavy rain causes reduction in friction — earth turns into mud and flows slowly over bedrock
16
Q
Mass movement: what are slides? (And 2 types?)
A
Slides: occurs when a portion of soil or rock along a steep slope suddenly gives way and moves downhill — aided by rainfall
- Rock fall: when mechanical weathering I.e freeze thaw breaks down large chunks of cliff away. Cliff has to be at angle of 40° or more
- Rock debris / landslide: lots of rainwater or waves can reduce friction — slabs of rock slide over underlying rock.
17
Q
Mass movement: what are slumps / under what conditions does it occur?
A
Slumps: Rotational movement of soil / debris moves downhill — steeper slopes experience rotational scars.
> This can repeat, forming a terraced cliff
Occurs in saturated conditions
18
Q
What are subaerial processes?
A
Processes occurring ‘at the base of the atmosphere’ which includes mass movement and weathering
19
Q
What factors affect erosion rate of cliffs / shorelines etc?
A
- high energy waves (I.e winds)
- absence of a beach
- rising sea levels
- coastal management / sea defences elsewhere along coast
- weathering / mass movement processes
20
Q
Describe the 4 erosion processes that chip rock away from cliff faces:
A
-
Hydraulic action:
Air trapped in cracks is compressed by force of waves; dislodges rock from cliffs -
Abrasion:
Sediment picked up by breaking waves is thrown against cliff face; chisels away at cliff face -
Attrition:
(process acts on already eroded sediment) sediment gets moved around by waves; gets smaller / rounded over time -
Corrosion:
carbonate rocks are vulnerable to solution by rainwater and spray from seawater
21
Q
Describe the 4 processes of transportation (size order)
A
LARGEST
-
Traction:
rocks / boulders roll along riverbed by force of water -
Saltation:
Stones / pebbles bounce along channel and hit each other -
Suspension:
Fine silt particles hang in water (makes it cloudy) -
Solution:
Minerals dissolve in water
SMALLEST
22
Q
In 4 steps, describe longshore drift
A
- Waves approach shoreline at an angle due to wind etc 30°
- 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 backswash
- Over time this changes the beaches shape
Groynes prevent longshore drift as the carries sediment is deposited against them keeping the sediment within that beach section
23
Q
What 3 factors affect wave energy? (Think wind)
A
-
Wind speed:
Higher windspeed means more wave energy -
Fetch:
Distance of open water over which a wave has travelled across makes a big difference on wave height and energy.
Larger fetch gives wave more chance to ‘grow’ -
Wind duration:
with a longer storm, the waves will be bigger
24
Q
Define weathering
A
Decay and disintegration of rocks in-situ. 3 types: mechanical, biological and chemical
25
Define erosion
Action of surface processes that removes soil, rock or dissolved material from one location to another
26
Why do waves break?
As you approach the shore, the depth of water is less, and the seabed is rough
Water at surface moves at faster rates than water deeper down
The circular orbit of water particles changes to an elliptical shape
Wavelength and velocity both decrease and wave amplitude increases
Force pushes the wave higher, making it steeper before it spills and breaks onshore
Water rushes up the beach as swash, and flows back to sea as backwash
27
Characteristics of a constructive wave? And what does this mean for erosion / deposition levels
- strong swash and weak backswash
- deposition > erosion
- low wave height and long wavelength
28
Characteristics of a destructive wave? And what does this mean for erosion / deposition levels
- weak swash and strong backswash
- erosion > deposition
- high wave height, short wavelength
29
Name the 6 depositional features (of beaches)
1. Beaches:
Formed by constructive waves piling up material ahead of them
2. Bars:
Joins 2 headlands
3. Spits:
Bank of sand / shingle protruding from coast into sea
4. Tombolo:
Where a spit links the mainland to an island
5. Sand dunes:
Hill or ridge beyond the reach of the tides
6. Cuspate Foreland:
Where 2 sediment cells converge to cause an accumulation of sediment
30
(Sediment cells) what are sources, transfers and sinks?
Sources:
Locations that sediment is removed from
Transfers:
Process that moves sediment between sources and sinks
Sinks:
Areas and landforms where sediment is stored
31
How many sediment cells are there in the UK?
11
32
What happens in a sediment cell / what are they?
Within each sediment cell, sediment moves between the beach, cliffs and sea through processes of erosion, transportation and deposition
Each cell operates between physical barriers that prevent the sediment from moving any further along the coast i.e estuaries
SEDIMENT BUDGET:
Amount of sediment available within a sediment cell
33
What is positive feedback / what is happening to the sediment budget / what is happening with rates of erosion and deposition?
If the sediment budget falls, waves continue to transport sediment (erosion may increase in some other areas)
One change has lead to another
I.e people walking over sand dunes destroys vegetation growing there and causes erosion
As destroyed roots from the vegetation have been holding the sand dune together, dunes are more susceptible to erosion
Eventually the dunes will be completely eroded leaving more of the beach open to erosion taking the beach further away from dynamic equilibrium
34
What is going on with the negative feedback loop concerning the sediment budget? + provide an example
Sediment budget increases, and more deposition is likely. The sea corrects itself as it can only carry so much.
Any surplus is deposited
I.e when destructive waves from a storm lose their energy excess sediment is deposited as an offshore bar
Bar dissipates wave energy protecting the coast from further erosion
Over time the bar gets eroded instead of the beach
Once the bar has gone normal conditions ensue and system goes back to dynamic equilibrium
35
What is the difference between isostatic and eustatic change?
Isostatic:
Occurs locally, when land rises or falls relative to the sea.
- Weight of glaciers makes land sink
- tectonic activity can shift the land
Eustatic:
Occurs on a global scale and relatively quickly, in glacial periods ice sheets form which stores water that was once stored in the ocean (now deducted from ocean)
36
Why will sea level rise happen?
- melting glaciers
- melting of ice sheets I.e Antarctic and Greenland
- thermal expansion
37
What are the 3 natural causes of coastal flooding?
3 main causes:
1. **Spring tides**
(Gravity of moon and sun combine)
2. **Storm surges**
(Short term local rise in sea level due to low air pressure)
3. **Rising sea levels**
Long term eustatic sea-level change
38
What are depressions in terms of weather / what causes them to form?
Intense low pressure weather systems.
They occur when a fast moving area of cold air moves into a region of warmer air, pushing this warmer air upwards. As it rises, air pressure falls
39
What 5 factors affect the risk from coastal flooding?
1. **Low lying coastal land** where land is <10m above sea level
2. **Coastal topography**, where coastline is too narrow to form tunnels
3. **Subsidence**, (sinking of land relative to sea level)
4. **Removal of coastal vegetation** i.e mangroves which helps bind sediment together and absorbs energy from tidal surges
5. **Eustatic sea level rise** caused by global warming leading to thermal expansion and ice sheets melting
40
In what 3 ways do plants stabilise sandy coastlines?
1. Roots of plants hold sediment together
2. When submerged, surrounding plants protect sediment from moving water
3. Plants protect sediment from from wind erosion
41
What is a mangrove swamp?
Mangrove swamp:
A collection of trees that are suited to
Coastal environments. Found in tropical waters and provide habitat for young fish
42
What are the 5 geomorphic process categories?
1. Erosion
2. Transportation
3. Deposition
4. Weathering
5. Mass movement
43
What is soft engineering?
An approach designed to work with natural processes in the coastal system in order to manage (not necessarily prevent) erosion
44
What is hard engineering?
This involves building structures along the coast (usually at the base of the cliff or on a beach)
45
What factors are considered when choosing either soft or hard engineering?
- whether you are protecting against flooding or erosion
- what the land is currently being used for
- how much money you will have
- where in the sediment cell the site is located
46
Name some examples of hard engineering and a pro / con for each
1. **Rip-rap (rock armour)**
- large boulders piled up
- breaks up wave energy
- at base of sea walls
Pro: reduces wave energy
Con: may become vegetated over time
£100-300k for 100 metres
2. **rock breakwater**
- large boulders piled up
- forces waves to break offshore rather than at coast
- reduces wave energy
Pro: deposition encouraged between breakwater and beach
Con: can interfere with longshore drift
£100-300k
3. **sea wall**
- concrete with steel reinforcement
- physical barrier against erosion
- act as flood barriers
Con: destruction of natural cliff face and foreshore environment
£6000 per metre
4. **revetments**
- made of stone, timber or interlocking concrete
- absorbs wave energy and reduces swash distance by encouraging infiltration
- reduce erosion on dune faces
Pro: reduce wave power
Con: may become vegetated
£4500 per metre
5. **Groynes**
- vertical stone or timber fences built perpendicular to the coast
- prevents longshore movement of sediment
£5000-10000 each
- encourages deposition
Pro: prevents longshore drift and sediment starvation
47
Name some examples of soft engineering and a pro / con for each
1. **Beach nourishment**
- addition of sand or pebbles to an existing beach making it higher / wider
- sediment dredged from nearby seabed
Pro: relatively cheap to maintain
Pro: increases tourist potential - more space
Con: needs constant maintenance
£300000 for 100 metre
2. **Dune stabilisation**
- marram grass planted to stabilise dunes
Pro: maintains a natural cost environment
Pro: provides wildlife habitats
Pro: relatively cheap
Con: time consuming to plant + grow
£200-2000 per 100 metre
3. **Marsh creation**
- form of managed retreat
-allows low lying coastal areas to flood, becomes a salt marsh
Pro: relatively cheap
Pro: wildlife habitat
Pro: natural defence - buffer for powerful waves
Con: agricultural land is lost
Cost is variable
48
What are the 4 preferred shoreline management policies / plans (SMP’s)? And a -ve and +ve for each
1. **No active intervention**
Pro: no costs
Con: users of the land would be losers when it erodes
2. **Hold the existing shoreline**
Pro: no loss of infrastructure
Con: more expensive
3. **Managed realignment of the shoreline**
Pro: creating things like salt marshes is biodiverse
Con: users of the land will be losers when it erodes
4. **Advance the existing shoreline**
Pro: protects against flooding, reduces erosion
Con: won’t last forever
49
What is cost benefit analysis?
It is completed before a coastal management project is approved.
Costs are forecast and then compared with the expected benefits i.e, value of land saved, relocating people etc
Costs / benefits in 2 categories
1. Tangible;
Costs and benefits are known and given a monetary value
2; intangible;
Costs may be difficult to assess but are important
Benefits > costs is ideal
50
What is an environmental impact assessment / what factors is it based on?
Completed before a coastal management project is approved
Quantitative means of estimating the environmental changes arising from a proposal
Based off of:
- environmental
- economic
- social factors
51
(Managing coastlines) what does engineering feasibility question?
- is it the right method?
- is it achievable?
- is it within budget?
- what are the risks?
52
(Managing the coast) what land use and value factors are considered?
- what is the coast used for, how much is it worth?
- what grade (1-5) is the agricultural land graded from?
53
(Managing the coasts) what political, environmental, economic and social reasons are there for managing coastlines?
- agriculture is a key employer in certain coastal areas
- tourism is a key industry along coasts
- prevent people needing to relocate
- may be routes that allow people to get to work (supports the economy) that need preserving
54
Define aquaculture:
Farming of aquatic organisms i.e., shellfish for food
55
Define adaption
Making changes to lessen the impact of something I.e, flooding
56
Define mitigation
Making effort to reduce the emission of greenhouse gases and so reduces the impacts of climate change i.e, alternative energy sources
57
What happens with ICZM?
Integrated coastal zone management
Complete sections of the coast are now being managed as a whole rather than by individual towns or villages
58
What short term factors is the littoral zone of a coast subjected to?
- tides
- storm surges
59
What long term factors is the littoral zone of a coast subjected to?
- climate change
- changes in sea level
60
Can rocky coastlines (I.e along western and northern Britain) withstand erosion or not?
Yes they can
- They are predominantly made of granite / basalt
- they are generally found in high energy environments
- erosion > deposition
61
What landforms are seen along rocky coastlines?
- headlands
- cliffs
- shoreline platforms (wave cut platforms)
62
What is a high energy coastline?
Those that are exposed to strong, steady zonal winds alongside high energy waves, often unprotected topography-wise
63
What is a low energy coastline?
Coasts sheltered from storms due to adjacent topographical features i.e headland, reefs etc, sheltered from winds etc
64
Are sandy and estuarine coasts low or high energy coastlines? (What effect does this have on waves / Erosional rates there?)
Low energy;
- less powerful waves
- sheltered
- deposition > erosion
65
Define relief
Variations in the elevation of the ground surface — can be low or high
66
What are the characteristics of a coastal plain landscape?
- young weak sedimentary rocks
- the wash area is known as a coastal plain — LOW RELIEF
- eastern and southern Britain
67
Define wave refraction
When waves turn and lose energy around a headland on an uneven coastline
68
Do discordant or concordant coastlines lead to the formation of Dalmatian coasts? Why?
Concordant coastlines: rise in sea levels lead to the flooding of widened river valleys between tall headlands
— the headlands become islands which run perpendicular to the headland
69
Do discordant or concordant coastlines lead to the formation of headlands and bays? Why?
Discordant;
Wave energy in concentrated on headlands and wave refraction is caused — this creates erosive features in these areas
Energy gets dissipated in bays leading to the formation of beaches etc
70
What type of habitat is made up of coastal Greenland that is regularly flooded by tides?
Salt marshes
71
What type of plant can survive in very dry conditions?
Xerophytes
72
What type of plant can survive in very saline conditions?
Halophytes
73
What type of trees are found in tropical water and provide an important habitat for young fish?
Mangrove swamps
74
What is dune succession?
When sand builds up into dunes raising the ground above sea level (when colonised by plants)
75
What is marsh succession?
When mud builds up in salt marshes raising the ground levels above sea level (when colonised by plants)
76
In the summer, do constructive or destructive waves dominate?
Constructive
77
In the winter, do constructive or destructive waves dominate?
Destructive
78
How do storms affect waves? How will climate change affect the impact of storms on the UK?
Storms cause more destructive waves
— climate change would mean an increase in destructive waves along UK coastlines due to storm surges
79
In what ways can hydraulic action occur and how does wave type, size and lithology affect this?
DESTRUCTIVE WAVES
- direct impact of water lodging itself into cracks
- force of the breaking wave compressing air into rocks
High energy waves with a large wave height are most efficient at erosion via hydraulic action
Effective on hard resistant igneous rocks
80
In what ways can abrasion occur and how does wave type, size and lithology affect this?
Abrasion is most effective with high energy waves that have a large wave height in order to hurl sediment at rock with more force
Soft sedimentary rock i.e chalk is eroded much more quickly
81
In what ways can corrosion occur and how does wave type, size and lithology affect this?
Most effective waves for corrosion are constructive waves as the force of impact is irrelevant — the spilling wave increases the amount of time for the chemical reaction to occur
Slower waves with longer wavelengths are better (prolongs contact of water and rock)
Carbonate rocks like limestone and sedimentary rocks get corroded the easiest
82
In what ways can attrition occur and how does wave type, size and lithology affect this?
Soft rocks I.e sandstone, chalk, clay get broken down by attrition much quicker
83
What are wave cut notches?
A curved indentation of about 1-2m high extending along the base of a cliff
Forms between the high and low tide marks where destructive waves impact against the cliff
Depth of notch depends on resistance of rock
84
What Erosional processes cause wave cut notches?
Hydraulic action predominantly although sometimes corrosion as well
85
What is a wave cut platform?
A flat rock surface exposed at low tide, extending out to sea from the bottom of a cliff
86
How are wave cut platforms formed?
1. wave cut notches deepen by further erosion until the overlying material collapses by mass movement due to gravity, forming a cliff
2. Process repeats and cliff retreats
3. the rock below sea level is always submerged and not eroded due to no wave exposure
4. left as flat platform
87
How are cliffs formed?
Wave cut notches deepen until the overlying rock collapses by mass movement due to the force of gravity which forms a cliff
88
How is a cave-arch-stack-stump sequence formed?
1. Joints, wave cut notches etc within headland rocks erode more rapidly, deepening and widening a weak point in the headland which forms a cave
2. Where a line of weakness extends h through the the headland, a cave forms on both sides
3. Marine erosion deepens the caves until they connect and form an arch
4. Hydraulic action and abrasion attack the sides of the arch between low and high tide forming more wave cut notches
5. The undercutting of the sides causes the collapse of some overlying material
6. Weathering and other subaerial processes attack the arch roof
7. Eventually the arch roof will collapse leaving the seaward end of the headland detached from the land as a stack
8. Marine erosion at the base of the stack will form notches around it until it collapses by blockfall
9. Remnants of the stack base form a stump, exposed only at low tide
NOT APPLICABLE FOR SOFT ROCKS
89
How is a spit formed?
Longshore drift occurs along the coast but as the waves lose energy (usually due to going behind a sheltered area) they deposit their sediment
Periodically wind will change direction and cause a ‘hook’ to appear at the end of the spit
Sheltered areas behind spits often turn into salt marshes
90
How is a bar formed?
When a spit crosses a bay and links up two sections of a coast — encloses a lagoon
91
How is a tombolo formed?
It is formed due to wave refraction off the coastal island reducing wave velocity, leading to the deposition of sediments
92
How is a cuspate foreland formed?
Longshore drift along a triangular shaped headland creates 2 beaches which join up to form a cuspate foreland
93
How is an offshore bar formed?
As waves don’t have enough sediment to carry onto shore, they can be formed as the wave breaks early instantly depositing its sediment
94
How is a sand dune formed?
When prevailing winds blow sediment to the back of the beach which allows the sand to dry so the sand is light enough to get blown further back
95
Define dynamic equilibrium
A state of balance between continuing processes
96
Why is weathering important in sediment production?
Weathering attacks the back shore and foreshore of the littoral zone:
This therefore creates rock fragments that form sediment
— it is the most active in the source zone of the sediment cell
97
How does weathering influence rates of recession? Why?
Weathering weakens rocks which makes marine erosion easier and faster, increasing rates of coastal recession
Wave cut notches cause cliffs to collapse, leading to faster recession
98
The type of mass movement that occurs depends on:
- angle of slope / cliff
- rocks lithology and geology
- vegetation cover of the cliff face
- saturation of ground / previous weather patterns
99
Mass movement: what is the difference between slides and flows?
Slides: sediment keeps in the same place within the whole material, it simply moves downhill
Flows: all the material flows downhill and mixes
100
What is the difference between lithology and geology?
Lithology: description of physical characteristics of a rock I.e colour, texture, grain, composition etc
Geology: study of rocks and minerals
101
What is blockfall?
Where rock fragments break away and either drop down vertically or bounce down slope
102
Sea level change: what are 3 short term causes of sea level change?
- high tide and low tide
- wind strength and direction
- atmospheric pressure
103
Sea level change: what are the 2 names for long term causes of sea level change?
1. Isostatic — localised sea level change
2. Eustatic — global sea level change
104
What could cause isostatic sea level change?
- **POST GLACIAL ADJUSTMENT** whereby glaciers once weighted down the land beneath, so the land subsides when it melts i.e the uk
- TECTONIC ACTIVITY I.e earthquakes and volcanoes may cause land **SUBSIDENCE**, therefore causing isostatic sea level increase
105
What could cause eustatic sea level change?
- **THERMAL EXPANSION**, as water gets warmer it expands which increases its volume — global warming
- water getting **stored in glaciers**, locked up on land in ice
- **CLIMATE CHANGE** — warmer temps lead to melting of glaciers which causes increased ocean water budget
106
What is an emerging coastline?
Parts of the littoral zone where a fall in sea level exposes land once part of the seabed
produced by post glacial adjustment
107
What are some features associated with an emerging coastline?
1. Raised beach;
- relic beach now above high tide level
- flat surface covered by stones / pebbles / boulders
- usually vegetated by plant succession
2. Fossil cliff
- steep slope found at the back of a raised beach
- may contain wave cut notches, caves and arches due to marine erosion containing fossils too
- relatively rapid sea level drops leave relic coast abandoned above high tide
I.e chesil beach
3. Raised stumps
108
What is a submergent coastline?
Sections of the littoral zone where sea level rise inundated areas that were previously part of terrestrial land
109
What are some features associated with an submergent coastline?
1. **Ria** — drowned river valley, making it much wider than would be expected
- common in peri glacial areas that were adjacent to land covered by ice
- rivers eroded steep v shaped valleys in the frozen landscape
I.e south Devon coast
2. **Fjord** — drowned glacial valleys which are flooded by the sea
- relatively straight profiles
- glacier erosion cuts deep into the landscape (below sea level)
- often have a shallow lip entrance formed by a ridge of terminal moraine
I.e Norway
3. **Dalmatian islands** — long narrow islands which run parallel to the coastline and are separated from the coast by narrow sea channels
- produced by rising sea level flooding the coastline containing folds aligned with parallel coast
- rising sea level flows over the top of low points in the rock and separating sections of it
I.e Croatia
110
What 3 main causes of sea level rise are there? What % does each one account for?
1. Warming leads to the melting of glaciers — increases the amount of water in the ocean store
ACCOUNTS FOR 50% SEA LEVEL RISE
2. Warming leads to thermal expansion of existing ocean water as temp rises
ACCOUNTS FOR 40% SEA LEVEL RISE
3. Tectonic activity
- Emission of geothermal heat due to underwater volcanic activity can lead to thermal expansion
- folding of plates increases basin volume lowering sea levels
- rising magma causing doming upwards of crust reduces ocean basin volume
- faulting can uplift sections of crust
ACCOUNTS FOR 10% SEA LEVEL RISE
111
What coastlines are at risk of rising sea level change?
- low lying ones
- low lying volcanic islands or coral atolls I.e Maldives
112
What geological factors leave coastlines susceptible to recession?
- lithology; soft rock type, porous rocks more susceptible
- geological structure; well jointed rocks, heavily faulted rocks, seaward dipping beds more susceptible
113
What marine factors lead to coastal recession?
- long wave fetch promoting large destructive waves
- strong longshore drift that quickly removes sediment allowing erosion to restart
114
How can human activity increase the rate of coastal recession?
1. Coastal management
By interrupting the operation of the sediment cell I.e construction of dams can trap river sediment which starves the coast of a sediment source
2. Dredging
Sand or gravel scooped up for the construction industry which removes it from the sediment cell
115
Coastal recession: how does wind direction / fetch influence recession in the short run
- rates of recession will be highest when wind direction blows onshore
- prevailing wind direction produces large destructive waves and rapid recession
- where wind blows from a direction with a large fetch, waves become more destructive and erosive
116
Coastal recession: how do tides influence recession in the short run? (how many times a day does high tide occur?)
- rates of recession are more rapid with a high tide due to deeper water in the foreshore zone, allowing waves to maintain higher energy when they reach the back shore
- high tides occur twice each day, 12 hours apart
117
Coastal recession: how do storms influence recession in the short run
- storm events are deep (low pressure) depressions
- they produce high energy, large destructive waves which make the rate of recession rapid
global warming is expected to increase the intensity of atmospheric circulation
118
Coastal recession: how do seasons influence recession in the short run
- storm events more likely to occur in the winter when contrast in temperature and pressure between tropical and polar air masses is greatest
- recession is more common in winter in the UK
119
Coastal recession: how do weather systems influence recession in the long run (think about the cells where UK is located)
- UK is located in the Hadley cell
— this interaction between the cool air from the polar cell and warm air from the Ferrell cell produces high air pressure anticyclone and low air pressure depression weather systems
Anticyclones: gentle winds and small waves
Depressions: strong winds and rapid rates of recession
120
Define fetch
Length of water for which a given wind is blown
121
Name some factors which affect the risk of coastal flooding?
- land subsidence (sinking of land relative to the sea)
- removal of vegetation, especially mangrove forests which help to bind sediment together and absorb energy from tidal surges
- building of sea defences
- storm surges
- climate change
122
What are some adaption and mitigation methods we have implemented to cope with inevitable sea level rising?
Adaptation:
- sea walls
- Earth embankments
- storm surge barriers across river mouths
- restoration of mangrove forests
Mitigation:
- reduce GCG emissions to limit level of global warming and hence sea level rise severity
123
What makes ICZM holistic?
- the entire coastal zone is managed, not just where breaking waves cause erosion
- it recognises management of the coast must be sustainable — economic development has to improve the quality of life of people
- each of the 11 uk littoral cells can be managed as an integrated unit
124
Why are poorer people typically losers when it comes to SMP approval?
- farmers and residents lack a formal land title so cannot claim compensation
- in many cases individual property owners take responsibility for coastal defences in the absence of government or local plans
125
What is beach nourishment?
Addition of sand and sediment to an eroding beach by humans. The new material will be eroded by the sea which saves the cliffs or sand dunes from erosion and recession
126
What is corrasion (mechanical weathering)?
Form of mechanical erosion where material and sediment is flung at the cliff face as waves break against it, this breaks up the rocks on the cliff face
127
What is a Dalmatian coastline?
A concordant coastline with several river valleys running perpendicular to the coast. They become flooded to produce parallel long islands and long inlets
128
What are fjords?
Long narrow inlets of sea water which is between steep mountains. They are created when sea levels rise relative to the land, flooding coastal glacial valleys
129
What is glacial erosion?
Removal of loose material by glacier ice, involving plucking, abrasion, crushing and basal meltwater
130
What is permeable rock?
Rock which allows rainwater to pass through
131
What is impermeable rock?
Rock which doesn’t allow rainwater to pass through
132
What is a Ria?
Type of coastal inlet which is deepest at the mouth, formed when sea levels rise causing river valleys to flood
133
What is a shoreline management plan (SMP)?
Identifies all of the activities, both natural and human, which occur within the coastline area of each sediment cell. They use this to recommend a combination of four actions for each stretch of that coastline:
- hold the line
- advance the line
- managed realignment
- no active intervention
134
If a beach has large pebbles on the back shore and smaller pebbles on the foreshore, does this suggest there are constructive or destructive waves?
Likely to be constructive: strong swash can reach and sort the large pebbles at the back shore (large moved to the top of beach), and the weak back swash can only drag / sort small pebbles to the foreshore
135
What is mass movement?
The downslope movement of material under the force of gravity: includes landslides, rotational slumping and blockfall
136
What are some negative impacts of mass movement?
- damage to / loss of land
- damage to / loss of infrastructure
- injury / fatality
- unstable ground surfaces
137
Are sedimentary rocks resistant to erosion?
No
