Coasts Flashcards
(100 cards)
1
Q
3.1 COASTS AS NATURAL SYSTEMS
Explain what is meant by “the coast as an open system”
A
- has inputs and outputs to other systems
- e.g. sediment to and from other sediment sources/stores
2
Q
3.1 COASTS AS NATURAL SYSTEMS
Define the following in the context of a coastal system, and give examples for each:
- energy
- stores/components
- flows/transfers
- inputs
- outputs
A
- energy: power/driving force of a system (e.g. waves)
- stores/components: individual elements/parts of a system (e.g. beach)
- flows/transfers: links/relationships between components (e.g. longshore drift)
- inputs: something from the outside coming into the system (e.g. sediment)
- outputs: something moving out of the system (e.g. waves/currents)
3
Q
3.1 COASTS AS NATURAL SYSTEMS
Define dynamic equilibrium in a coastal system
A
when there is a balance of inputs and outputs in a constantly changing system
4
Q
3.1 COASTS AS NATURAL SYSTEMS
How does a positive feedback cycle differ from a negative feedback cycle? Give examples for each in the context of coastal systems
A
+ve feedback cycle: enhances and amplifies change, moving it further away from its equilibrium and more unstable (e.g. terminal groyne syndrome: groynes trap sediment and build up one part of the beach but starves the coast further down of sediment, so it’s more vulnerable to erosion and therefore erodes faster)
-ve feedback [cycle]: a flow/transfer leads to a decrease or decline, brings system back into its equilibrium (e.g. wave-cut platforms - base of cliff is eroded and undercut, cliff above it collapses, wave-cut platform formed, gradually platform grows, acts as a buffer to slow erosion down)
5
Q
3.1 COASTS AS NATURAL SYSTEMS
How do landforms combine to form characteristic landscapes?
A
- Landforms are natural features or individual components which form part of the wider landscape.
- A landscape is part of the earth’s surface which can be viewed at one time from one place; it consists of geographical features that are characteristics of a particular area
6
Q
3.1 COASTS AS NATURAL SYSTEMS
Illustrate how the coastal system links with other natural systems
A
runoff:
- when overland flow occurs down a slope or cliff face, small particles are transferred in the flow to enter the littoral zone, potentially acting as/forming an input to the coastal system.
- toxic chemicals can contaminate storm water and threaten ecosystems on the coast
7
Q
3.2 SOURCES OF ENERGY AT THE COAST
Outline the differences between high-energy and low-energy coastlines
A
high-energy:
- tend to be rocky
- powerful/high energy waves (due to strong prevailing winds and large fetch)
- creates landforms such as headlands and bays, cliffs, wave-cut platforms
- rate of erosion > rate of deposition
low-energy:
- tend to be sandy/estuarine
- less powerful waves or where the coast is sheltered from the waves
- creates landforms such as beaches, spits, salt marshes
- rate of deposition > rate of erosion
8
Q
3.2 SOURCES OF ENERGY AT THE COAST
Demonstrate how the sun and wind is the energy behind the waves
A
- the sun is the primary source of energy for all natural ecosystems
(- the wind transfers energy to the water) - wave energy is determined by:
- strength of wind (determined by pressure gradient)
- duration of the wind (longer duration => more powerful waves)
- fetch (distance of open water over which wind blows) (longer fetch => more powerful waves)
9
Q
3.2 SOURCES OF ENERGY AT THE COAST
How does Coasts link to the core concept of causality?
A
causality is the relationship between cause and effect, such as the processes of erosion, weathering, transportation, deposition and mass movement cause the formation of different landforms on a landscape
10
Q
3.2 SOURCES OF ENERGY AT THE COAST
How are waves formed?
A
- as air moves through the water, frictional drag disturbs the surface and forms ripples or waves
- as water approaches the shore, driven by the wind in a circular orbit, the water becomes shallower and the circular orbit of the water particles becomes an elliptical shape
- the wavelength and velocity both decrease, wave height increases, causing water to back up from behind and rise to a point where it starts to topple over (break)
- the water rushes up the beach as the ‘swash’ and back down as the ‘backwash’
11
Q
3.2 SOURCES OF ENERGY AT THE COAST
How are beaches and waves an example of a negative feedback?
A
- constructive waves are associated with relatively gentle beach profiles, enabling waves to surge a long way up the beach
- but over time, more beach material accumulates, the beach steepens (working against the propagation (multiplication/spreading etc) of the constructive waves
- the waves become more destructive (plunging rather than surfing), removing material from the beach and depositing it just offshore
- this results in the profile becoming less steep, encouraging constructive waves rather than destructive waves to form
- this ‘toing and froing’ is a balancing act that will, all things being equal, result in a state of dynamic equilibrium
12
Q
3.2 SOURCES OF ENERGY AT THE COAST
How does Coasts link to the core concept of vulnerability and resilience?
A
- the coastline is constantly and increasingly VULNERABLE to erosion, due to continuous processes like weathering and erosion
- by building defences to protect and maintain the coast, we are demonstrating RESILIENCE
13
Q
3.2 SOURCES OF ENERGY AT THE COAST
Illustrate the difference between constructive and destructive waves in terms of:
- formation
- wave form
- wave break
- beach gain/loss
- beach profile
A
FORMATION
- constructive: caused by distant weather systems in open oceans
- destructive: caused by local storms
WAVE FORM
- constructive: low surging waves, long wavelength
- destructive: high plunging waves, short wavelength
WAVE BREAK
- constructive: stronger swash, weaker backwash
- destructive: stronger backwash, weaker swash
BEACH GAIN/LOSS
- constructive: gain
- destructive: loss
BEACH PROFILE
- constructive: usually gentle, but will eventually build up/steepen breach
- destructive: usually steep, but will eventually flatten beach
14
Q
3.2 SOURCES OF ENERGY AT THE COAST
How does a Neap tide differ from a Spring tide?
A
Neap tides occur when the moon and sun are at 90° to the Earth
~~> low tidal range (low high tide and high low tide)
Spring tides occur when the moon and sun are parallel to the Earth
~~> high tidal range (high high tide and low low tide)
15
Q
3.2 SOURCES OF ENERGY AT THE COAST
How does a rip current form?
A
1) waves break onto shore
2) sandbars => water accumulates at shore
3) opposing waves come in => fight against the accumulation of water created by sand bank/bar
4) causes a surge of current out to sea as the water tries to escape
5) circulation of incoming waves of varying strength meets outgoing surge of current
16
Q
3.2 SOURCES OF ENERGY AT THE COAST
What is wave refraction? How is this an example of negative feedback?
A
wave refraction: the distortion/bending of waves as they approach an indented shoreline
- as the waves approach the headland, the energy is concentrated on the headlands and dissipated in the bays
- => more erosion of headland and more deposition in bays
- gradually …
FINISH THIS CARD
17
Q
3.2 SOURCES OF ENERGY AT THE COAST
How does a high-energy coast differ from a low-energy coast?
A
HIGH-ENERGY COASTLINES:
- rocky
- high energy/powerful waves
- creates cliffs, headlands and bays, wave-cut platforms
- rate of erosion > rate of deposition
LOW-ENERGY COASTLINES:
- sandy beach or estuarine
- less powerful waves or where the coast is sheltered from waves
- creates beaches, spits
- rate of deposition > rate of erosion
18
Q
3.3 SOURCES OF ENERGY AT THE COAST
What are the 6 sources of energy at the coast?
A
- waves
- wind
- tides
- currents
- storm surges
- sun
19
Q
3.3 SEDIMENT SOURCES, CELLS AND BUDGETS
What are the 6 global sources of sediment?
A
- rivers
- cliff erosion
- longshore drift
- wind
- glaciers
- offshore
20
Q
3.3 SEDIMENT SOURCES, CELLS AND BUDGETS
Explain the concept of sediment cells
A
- a stretch of coastline usually between two headlands where the movement of sediment is contained
- the sediment system has SOURCES/INPUTS (primarily derived from the river, coastal erosion and offshore sources such as bars/banks), TRANSFER/FLOWS (longshore drift, rip currents etc) and STORES/SINKS (beach, sand dunes, offshore bars etc)
- there are 11 around England and Wales
21
Q
3.3 SEDIMENT SOURCES, CELLS AND BUDGETS
What are sediment budgets?
A
- the balance of sediment being added and removed from a system
- cells achieve a state of dynamic equilibrium by having the rate of erosion = rate of deposition
22
Q
3.3 SEDIMENT SOURCES, CELLS AND BUDGETS
Hypothesise what can impact sediment budgets.
A
- floods
- severe storms (storm surges are a source of sediment)
- coastal management (groynes, sea walls etc)
23
Q
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
Detail mechanical weathering at the coast
(define and give 3 examples)
A
The breaking up of rocks, no chemical change takes place
- freeze-thaw/frost shattering
- salt crystallisation: salt water evaporates, leaves salt crystals behind, grow over time, exert stress on the rock, breaks it apart
- wetting and drying: clay in rock expands when wet, contracts when dry, continuous cycle, causes cracks in rock which expand gradually and break apart the rock
24
Q
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
Illustrate what biological weathering is at the coast
(define and give 4 examples)
A
The breakdown of rocks by organic activity
- thin plant roots: grow into cracks in rock which widen and break apart as roots grow
- water running: water runs over decaying vegetation, becomes acidic => increased chemical weathering
- burrowing: rabbits, bird nests etc
- marine organisms: burrowing and secreting acids
25
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
How is chemical weathering displayed at the coast?
Chemical reactions, salts may be dissolved or a clay-like deposit may result which can then be easily eroded
- carbonation: rainwater absorbs CO2 from air to form weak carbonic acid; reacts with calcium carbonate in rocks (e.g. limestone, chalk) to form calcium bicarbonate which is easily dissolved
- oxidation: rock + oxygen --> rusty red powder => rock is more vulnerable to weathering
- solution: dissolving of rock minerals
26
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
Contrast soil creep and mudflows
MUDFLOW
- flow
- usually quite rapid
- above ground/surface level
SOIL CREEP
- creep
- imperceptible/extremely slow
- zig-zag movement from deep underground to surface, back and forth downhill
27
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
Demonstrate the difference between a landslide, a landslip and a rockfall
LANDSLIDE
- flat, downhill surface
- block of material, remaining intact, moved rapidly downhill along a planar surface
- frequently triggered by earthquakes or heavy rainfall
LANDSLIP/SLUMPING
- curved, downhill surface
(- land 'slips' down a bit)
- sharp break of the slope and the formation of a scar
- frequently triggered by pore water pressure build-up, due to impermeable rock overlying permeable rock
ROCKFALL
- vertical, steep cliff face
- sudden collapse or breaking away of individual rock fragments (or a block of rock)
- frequently triggered by mechanical weathering (particularly freeze-thaw) or an earthquake
28
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
Outline the difference between soil creep and solifluction
soil creep: extremely slow zig-zag movement of soil particles down a hill
solifluction: very similar but specific to periglacial environments
29
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
What is Soil creep?
- extremely slow movement of soil particles downhill
- particles rise towards ground surface due to wetting or freezing, then return vertically back down the hill in response to gravity
- zigzag movement similar to longshore drift
30
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
What is a Mudflow?
- earth and mud flowing downhill, usually over unconsolidated/weak bedrock (e.g. clay), often after heavy rainfall
- sudden, fast-moving (significant natural hazard)
- water gets trapped within rock => increased pressure =>rocks forced apart => slope failure
- pore water pressure (form of energy) determines instability of the slope
31
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
What is a Landslide?
- block of rock moving rapidly down a planar surface (slide plane), often a bedding plane that is roughly parallel to the surface
- material remains largely intact
- triggered by earthquakes or heavy rainfall (slip surface lubricated by rain)
32
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
What is Rockfall?
- sudden collapse or breaking away of individual rock fragments
- vertical/steep cliff face in heavily jointed and often quite resistant rock
- triggered by mechanical weathering (freeze-thaw) or an earthquake
- material that has fallen away accumulates at the base of the slope to form a "scree", which forms an input for a sediment cell and a temporary store for a coastal system
33
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
What is Runoff?
- overland flow carries small particles downslope to the littoral zone (longshore drift), potentially forming an input to the sediment cell
- can transfer toxic chemicals in the flow of storm water which threats ecosystems
34
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
What is Slumping?
- curved slide surface
- occurs in weak, unconsolidated clays and sands
- often when permeable rock overlies impermeable rock => build-up of pore water pressure
(- land 'slips' down a bit)
35
3.4 WEATHERING, MASS MOVEMENT AND RUNOFF
What is Solifluction?
- similar to soil creep but specific to periglacial environments
- summer: surface layer of soil thaws and becomes extremely saturated because it lies on top of permafrost (frozen (and therefore impermeable) ground)
- sodden soil moves downhill by a combination of 'heave' and 'flow'
36
3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: EROSION
What is hydraulic action?
the sheer force of water as it crashed against the coastline
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3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: EROSION
What is wave quarrying?
the action of waves breaking against unconsolidated material, and scooping out loose material (similar fashion to a digger)
38
3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: EROSION
What is corrasion?
transported sediment hurled at cliff foot, chipping away at the rock
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3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: EROSION
What is abrasion?
continuous process of sediment dragged up and down or across the shoreline, eroding and smoothing rocky surfaces (sand paper effect)
40
3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: EROSION
What is solution (corrosion)?
weak acids in seawater can dissolve alkaline rock (chalk/limestone) or alkaline cement that bonds rock particles together (may be indistinguishable from carbonation (chemical weathering), processes work simultaneously)
41
3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: EROSION
What factors affect coastal erosion? Name 6
WAVES - large, destructive waves => more erosion
LITHOLOGY (rock type) - more resistant to erosion (granite) vs less resistant to erosion (clays)
GEOLOGICAL STRUCTURE - crack, joints, faults => weaknesses, exploited by erosion
SUBAERIAL PROCESSES - weathering/MM => weakens cliffs + makes piles of debris (easily eroded by sea) => more erosion
PRESENCE/ABSENCE OF A BEACH - beach = buffer, absorbs wave energy => less erosion w/ beach
COASTAL MANAGEMENT - groynes => wider beaches (sediment trapped) but terminal groyne syndrome too. sea walls => reflect wave energy elsewhere => more erosion there instead
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3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: TRANSPORTATION
What is traction?
rolling of course sediment along the seabed that is too heavy to be picked up and carried by the sea
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3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: TRANSPORTATION
What is saltation?
sediment bounced along seabed, light enough to be picked up or dislodged but too heavy to remain in flow of water
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3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: TRANSPORTATION
What is suspension?
smaller (lighter) sediment is held in the flow of water
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3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: TRANSPORTATION
What is solution?
chemicals dissolved in the water, transported and precipated elsewhere
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3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: TRANSPORTATION
What factors affect the rate of transportation? Name 2
VELOCITY (ENERGY)
PARTICLE SIZE (MASS)
high energy environments => larger particles able to be transported
low energy environments => only finest particles (clays) able to be transported
47
3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: TRANSPORTATION
What is longshore drift/littoral drift? (LSD)
1) waves approach beach at angle of prevailing wind
2) gravity => backwash pulls material down beach @ 90 degrees to shore
3) net zigzagging movement of sediment up and down the beach = longshore drift
48
3.5 MARINE PROCESSES - EROSION, TRANSPORTATION, DEPOSITION: DEPOSITION
What is deposition and when does it occur?
- sediment/material being dropped in areas with low energy
- occurs when the velocity of water (or wind) falls below a critical value for a particular size of particle and can no longer be transported
49
3.6 LANDFORMS AND LANDSCAPES OF EROSION
List 8 landforms of coastal erosion
headland + bay, crack, cave, arch, stack, stump, wave-cut platform, cliff
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3.6 LANDFORMS AND LANDSCAPES OF EROSION
Explain the formation of wave-cut platforms (WCP) (from cliffs)
1) waves break @ foot of cliff
2) energy is concentrated on a small area (foot) => cliff is undercut
3) undercutting => wave-cut notch forms
4) further erosion concentrated at foot of cliff => wave-cut notch gets bigger/deeper
5) increased stress on unsupported cliff above => collapses
6) after successive collapses, cliff line begins to retreat and WCP (gently sloping) forms at base of cliff
negative feedback cycle! WCP acts as buffer
51
3.6 LANDFORMS AND LANDSCAPES OF EROSION
Explain what a cliff profile is, and the 2 different types
cliff profile: the height & angle of a cliff face, including its features (WCN or changes in slope angle)
- steep, unvegetated cliffs: occur where marine erosion dominates; little to no debris (broken up by attrition + transported offshore)
- shallow-angled, vegetated cliffs: occur where marine erosion is not very active; lots of debris at base
52
3.6 LANDFORMS AND LANDSCAPES OF EROSION
Briefly illustrate the cliff profile features of caves, arches, stacks and stumps
cave develops crack -> crack exploited by weathering/MM/erosion
-> crack turns to cave -> back of cave (sometimes from the outside/other side too) is eroded and wears through -> cave turns to arch -> roof of arch is weathered (often freeze-thaw) -> roof collapses to form a stack -> base of stack eroded -> topples and forms a stack
53
3.6 LANDFORMS AND LANDSCAPES OF EROSION
Describe how headlands and bays are formed
bands of softer and harder lie at 90 degrees to the sea -> harder rock is more resistant to erosion (erodes slower) -> headland forms. softer rock is less resistant to erosion (erodes faster) -> bays form.
54
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Describe how beaches are formed
beach accretion takes place during a prolonged period of construction waves driven by storms 100s miles away
low-energy waves deposit sand to form a beach (caused by wave refraction
destructive waves reduce the width of the beach, constructive waves build up the beach
55
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Present the difference between swash-aligned and drift-aligned beaches
SWASH-ALIGNED
- parallel to incoming waves
- minimal LSD
- found on irregular coastlines, where LSD is difficult as waves arrive head-on
DRIFT-ALIGNED
- parallel to direction of LSD (prevailing wind)
- considerable LSD (sediment deposited)
- on regular coastlines
56
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Explain how beach profiles change
seasonal changes in wave type create summer and winter profiles - sediment is dragged offshore by destructive waves in winter and is returned by construction waves in summer
- summer = steeper beach profile: more constructive waves than destructive. constructive waves are less frequent => longer wavelength => energy dissipates => deposits
- winter = gentler beach profile: more destructive waves => higher frequency => berms eroded by plunging waves + high energy swash onto beach => strong backwash transports sediment back offshore
57
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Illustrate the difference between spits, bars/barrier beaches and tombolos
spit: extended area of deposited sediment in a straight line from the coastline (simple or compound (w/ barbs))
bar/barrier beach: extended area of deposited sediment which joins two headlands
tombolo: extended area of deposited sediment which joins a headland/coast to an island
58
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Explain what an offshore bar(/sandbar) is
- acts as both a sediment sink and potentially as an input into stores
- submerged/partly exposed ridges of sand/coarse sediment created by waves offshore from coast
- destructive waves erode the sand from the beach and deposit it offshore
- offshore bars/sand bars can absorb wave energy => reduces the impact of incoming waves
59
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Illustrate the formation of sand dunes
1) sand accumulates behind an obstacle
2) embryo dune forms and colonising vegetation (pioneer species)(sea rocket) stabilises it
3) vegetation binds dune => fore dune
4) yellow dune (marram grass here)
5) grey dune (low shrubs (brambles))
6) depressions between dunes can develop into dune slacks (damper areas (close to water table)
7) mature dunes/climatic climax community (oak/pine woodland)
60
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Outline the coastal landscape of mudflats and saltmarshes
- low energy, lots of deposition and mud due to low velocity
- eventually, mudflats can turn into saltmarshes
- saltmarshes are areas of flat, silty sediments that accumulate around estuaries/lagoons
they develop:
- in sheltered areas with deposition:
- where salt and freshwater meet (estuaries)
- where there are no strong tides or currents to prevent deposition
61
3.7 LANDFORMS AND LANDSCAPES OF DEPOSITION
Outline how mudflats and saltmarshes form
1) mud deposited close to high-tide line, dropping out of water (flocculation) (tiny particles of clay/mud stick together so they sink
2) pioneer plants (eelgrass) (halophytes) colonise and stabilise mudflat. other halophytes (cordgrass) help slow tidal flow and trap more mud and silt
3) gradually, mud level rises above high-tide, lower saltmarsh develops w/ wider range of plants (no longer need to be so well adapted to salty conditions)
4) soil conditions improve, vegetation succession continues to form a meadow
5) eventually, shrubs and trees colonise area as succession reaches its climatic climax
62
3.8 SEA LEVEL CHANGE
What evidence is there of long-term sea level change at the coast?
during quaternary period, there were several alternating glacial and interglacial periods, during which the sea levels rose and fell in response to the nature of precipitation
63
3.8 SEA LEVEL CHANGE
Outline the difference between eustatic and isostatic change
EUSTATIC: the rise and fall of sea levels (global scale)
- glacial periods => precipitation in form of snow; forms huge ice sheets that store water
- => slows hydrological cycle
- =>decreases sea levels
ISOSTATIC: the rise and fall of sea levels relative to the land (local scale)
64
3.8 SEA LEVEL CHANGE
Outline the difference between eustatic sea level change in glacial periods vs interglacial periods
GLACIAL PERIODS: precipitation in form of snow; forms huge ice sheets that store water=> slows hydrological cycle =>decreases sea levels
INTERGLACIAL PERIODS: temp rises => ice sheets melt and retreat => stored water then flows into rivers and seas => sea levels rise
65
3.8 SEA LEVEL CHANGE
Outline the difference between isostatic subsidence and isostatic recovery. Which occurs in glacial periods and which occurs in interglacial periods?
ISOSTATIC SUBSIDENCE: enormous weight of ice sheet compresses land and makes it sink, making the sea levels APPEAR to rise
- glacial periods
ISOSTATIC RECOVERY: ice sheet melts and its weight is reduced, making the land rise
- interglacial periods
66
3.8 SEA LEVEL CHANGE
What evidence is there for isostatic change in the UK?
land in the north and the west (which was covered by ice sheets in the last ice age) is still rising as a result of isostatic recovery
land in the south and east (which ice sheets never covered) is sinking. rivers pour sediment + water into Thames Estuary and English Channel, and the weight of this sediment causes the land to sink and sea levels APPEAR to rise
67
3.8 SEA LEVEL CHANGE
What do we know about the link between sea level change and tectonic activity?
uplift of Mt ranges at collisional and destructive margins have resulted in a relative fall in sea levels
(- however there has been some tilting of land at destructive plate boundaries whereby ports have been submerged)
68
3.8 SEA LEVEL CHANGE
Describe the features of emergent coastal landforms vs submergent coastal landforms
EMERGENT LANDFORMS:
- raised beaches/marine platforms: former WCP, cliffs are at a higher level than the present sea level
- relict cliffs: remains of eroded cliff (including caves, arches, stacks etc.), can be seen behind raised beach
SUBMERGENT LANDFORMS:
- rias: river valley flooded by rising sea levels (rias and river both start with 'ri')
- fjords: glacial valley flooded by rising sea levels
- dalmatian coastline: tips of ridges and runnels close to the coastline,
69
3.8 SEA LEVEL CHANGE
What caused the creation of a dalmatian coast? Give an example of a dalmatian coastline.
- ridges and runnels run parallel to the coast
- sea levels rise => valleys flood
- tops of ridges are left exposed (these form the offshore islands that run parallel to the coast that we can see
example: Croatian coastline
70
3.8 SEA LEVEL CHANGE
Kiribati - What's the story?
Think: where, what, causes, potential impacts, response... BUT?
Kiribati is an island in Pacific Ocean, threatened by sea level rise
Causes:
- much of the 'atolls' (small islands) are no higher than 6ft above sea level => very vulnerable
- global warming + ice melting + thermal expansion => sea level rise
Potential impacts:
- inundation => saltwater intrusion damages agriculture
- inundation of causeways => damage to economy and socio-economic links
- wells contaminated with sea water => unusable
Response:
- adaption: mangrove replanting, improving water supply management, strengthening laws to reduce coastal erosion, population settlement planning to reduce personal risks
BUT: government of Kiribati is negotiating with other countries (New Zealand, Australia) for new inhabited areas WHEN (not if) their island disappears
- given up?
71
3.9 COASTAL MANAGEMENT
Name 5 hard engineering strategies and 4 soft engineering strategies at the coast
HARD ENGINEERING: groynes, sea wall, rock armour, revetments, offshore breakwater
SOFT ENGINEERING: beach nourishment, saltmarsh creation, dune regeneration, cliff regarding + drainage
72
3.9 COASTAL MANAGEMENT
Outline groynes and their effectiveness as a hard engineering strategy at the coast
Groynes: timber/rock structures that jut out to sea. they trap sediment from LSD and build up the beach
+ works alongside natural processes to build up the beach
+ relatively cheap
- eyesore, unnatural
- terminal groyne synrome
73
3.9 COASTAL MANAGEMENT
Outline offshore breakwaters and their effectiveness as a hard engineering strategy at the coast
Offshore breakwater: partly submerged rock barrier, designed to break waves before they hit the coastline
+ effective permeable barrier
- visually unappealing
- potential navigation hazard
74
3.9 COASTAL MANAGEMENT
Outline sea walls and their effectiveness as a hard engineering strategy at the coast
Sea wall: stone/concrete structure, sometimes curved, to absorb/ reflect waves energy back to sea
+ effective prevention of erosion
+ often have promenade for a walk way (tourist attraction)
- reflect wave energy rather than absorb it => more erosion further down
- expensive to build and maintain
75
3.9 COASTAL MANAGEMENT
Outline revetments and their effectiveness as a hard engineering strategy at the coast
Revetments: sloping wooden/rock/concrete structures, top of beach or foot of cliff. break up wave energy
+ relatively cheap to build
- lots of maintenance
- unnatural looking
76
3.9 COASTAL MANAGEMENT
Outline rock armour and its effectiveness as a hard engineering strategy at the coast
Rock armour: large rocks @ bottom of cliff or foot of beach, which break up wave energy
+ cheap
+ easy to build and maintain
+ often used for recreation (fishing, sunbathing)
- intrusive
- dangerous for people to climb on
77
3.9 COASTAL MANAGEMENT
Outline beach nourishment and its effectiveness as a soft engineering strategy at the coast
Beach nourishment: addition of sand/shingle => wider beach, sediment is usually locally sources
+ cheap and easy to maintain
+ increases tourism
+ natural looking
- needs constant maintenance (LSD is constant)
78
3.9 COASTAL MANAGEMENT
Outline saltmarsh creation and its effectiveness as a soft engineering strategy at the coast
Saltmarsh creation: allowing coastal areas to flood, creates saltmarshes for habitats
+ cheap and sustainable
+ natural buffer
- agriculture lost
- compensation needed to farm + land owners
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3.9 COASTAL MANAGEMENT
Outline cliff regarding & drainage and its effectiveness as a soft engineering strategy at the coast
Cliff regarding: changing the angle of the cliff to stabilise it
Cliff drainage: removing H2O from cliff to prevent landslides and slumping
+ drainage is cost-effective
+ uniquely effective on clay/loose rock
- regarding => cliff retreat
- drained cliffs can dry out => cliff collapse
80
3.9 COASTAL MANAGEMENT
Outline dune regeneration and its effectiveness as a soft engineering strategy at the coast
Dune regeneration: planting marram grass (stability) and fencing off sand dune areas
+ maintains natural environment
+ creates habitats
+ cheap and sustainable
- takes time to plant
- negative reactions (tourists complaining that areas are fenced off)
81
3.9 COASTAL MANAGEMENT
Explain how a SMP is different from an ICZM. Give one example for where each is used
SMP (Shoreline Management Plan): aims to protect a certain sediment cell. strategies: hold the line, advance the line, managed retreat, do nothing
- used at HOLDERNESS
ICZM (Integrated Coastal Zone Management): aims to holistically establish sustainable levels of economic and social activity
- used in ODISHA
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3.9 COASTAL MANAGEMENT
What is a cost-benefit analysis and what two types are there?
Cost-Benefit Analysis (CBA): process by which the financial, social and environmental costs are weighed up against the benefits of a proposal in terms of social outcomes as well as profits and loss
tangible CBA: costs and benefits are known and can be given a monetary value
intangible CBA: costs may be difficult to calculate but are more important
83
3.10 COASTAL MANAGEMENT: HOLDERNESS
Finish these sentences about the Holderness Coastline:
The Holderness Coastline is in the _____ of England.
It forms a subcell in Sediment Cell __.
It comprises of 3 coastal units: _____________ ________ (made of chalk), ______________ ______ (characterised by a rapid rate of retreat), and _________ _______ ______ (formed at the Humber Estuary).
The main input into this system is ________ ____________.
The Holderness Coastline is in the EAST of England.
It forms a subcell in Sediment Cell 2.
It comprises of 3 coastal units: FLAMBOROUGH HEAD (made of chalk), BRIDLINGTON BAY(characterised by a rapid rate of retreat), and SPURN HEAD SPIT (formed at the Humber Estuary).
The main input into this system is CLIFF EROSION.
84
3.10 COASTAL MANAGEMENT: HOLDERNESS
Outline what management strategies are used in Hornsea on the Holderness Coastline, and the impacts (1 positive, 1 negative) of them
HORNSEA: sea wall, groynes, rock armour
+ hard engineering => effective protection from coastal erosion => wider beaches => increased tourism
- further south of Hornsea there is terminal groyne syndrome => increased vulnerability to erosion
85
3.10 COASTAL MANAGEMENT: HOLDERNESS
Outline what management strategies are used in Mappleton on the Holderness Coastline, and the impacts (1 positive, 1 negative) of them
Bonus: how much did these strategies cost?
MAPPLETON: groynes, revetments (cost £450 million)
+ hard engineering => effective protection from coastal erosion => wider beaches => increased tourism
- increased erosion at Cowden (terminal groyne syndrome from Mappleton groynes)
86
3.10 COASTAL MANAGEMENT: HOLDERNESS
Outline what management strategies are used in Easington on the Holderness Coastline, and the impacts (1 positive, 1 negative) of them
EASINGTON: groynes, rock armour, revetments
+ hard engineering => effective protection from coastal erosion => wider beaches => increased tourism
- revetments are costly and don't cope well with strong waves
87
3.10 COASTAL MANAGEMENT: HOLDERNESS
Outline what management strategies are used at Spurn Head on the Holderness Coastline, and the impacts (1 positive, 1 negative) of them
SPURN HEAD: abandonment/"do nothing" (SMP)
+ saved annual costs of protection
- people with cast-related jobs may have to move
88
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA
Finish the following sentences on the location of Odisha:
Odisha is located on the _________ coast of India, bordering _____ ___ __________.
It is a relatively ___________ coastline with a few natural _______/________.
The ___________ _______ support the bulk of the state's population.
The coastline is nearly ____km long.
Odisha is located on the EASTERN coast of India, bordering BAY OF BENGAL.
It is a relatively STRAIGHT coastline with a few natural INLETS/HARBOURS.
The COASTAL PLAINS support the bulk of the state's population.
The coastline is nearly 500km long.
89
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA
Give 4 reasons why Odisha is a distinctive coastline. How does this compare to the Holderness Coastline?
- relatively straight coastline
- lots of deposition
- lots of deltas
- lots of wildlife (birds, turtles, crocodiles)
Holderness coastline is much less straight and has rapid rates of erosion rather than deposition
90
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA
Outline 5 economic opportunities for human occupation and development in Odisha
- 35% coast has minerals + heavy metal deposits
- opportunities for offshore oil and natural gas (+ seabed mining)
- locals employed in coastal fishing and increasingly in aquaculture (shrimps)
- cultural and archaeological sites => tourism
- beaches + wildlife sanctuaries => tourism
91
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA
Outline 4 environmental opportunities for human occupation and development in Odisha
- wide variety of flora (plants) (marine and coastal) (saltmarshes, seagrasses, mangroves, sand dunes, estuaries, lagoons)
- variety of marine life (fish, reptiles, mammals, turtles, seaweeds)
- huge potential for offshore wind, tidal and wave power
- Chilika Lake bird sanctuary boasts over 150 migratory and resident species of birds
92
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA
Outline 4 risks for human occupation and development in Odisha
- increasing rates of erosion
- storm surges
- rising sea levels
- seasonal variations (accretion in summer, erosion in winter)
93
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA
Outline the 3 key findings from the 'Assessment of Shoreline Changes' in Odisha
- the coast is largely accreting (46.8%) (36.8% is eroding, 14.4% is stable)
- most accretion is in the north
- most erosion is in the south (major structures have interfered wth natural processes, exacerbating (extreme increase of) erosion rates
94
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA: EVALUATING HUMAN RESPONSES OF RESILIENCE, MITIGATION AND ADAPTATION
Comment on Odisha's resilience as a coastal system to tropical cyclones
- developing ecotourism: using the coastline for income
- replanting mangroves: helps with erosion, flooding, sea level rise, absorbs wave energy from storm surges
95
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA: EVALUATING HUMAN RESPONSES OF RESILIENCE, MITIGATION AND ADAPTATION
Comment on Odisha's mitigation in a coastal system to tropical cyclones
- relief supplies ready ahead of an approaching storm
- replanting mangroves: helps with erosion, flooding, seal level rise, absorbs wave energy from storm surges
- cyclone shelters
- broadcasting warnings
96
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA: EVALUATING HUMAN RESPONSES OF RESILIENCE, MITIGATION AND ADAPTATION
Comment on Odisha's adaptation as a coastal system to tropical cyclones
- replanting mangroves: reduces impact of tropical cyclones (absorbs energy from storm surge)
- cyclone shelters: helps with survival in emergencies
97
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA: EVALUATING HUMAN RESPONSES OF RESILIENCE, MITIGATION AND ADAPTATION
Managing the coast: What are the 3 aims of the ICZM?
Aims of ICZM:
- establishing sustainable levels of economic and social activity
- resolve environmental, social and economic challenges and conflicts
- protect the coastal environment
98
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA: EVALUATING HUMAN RESPONSES OF RESILIENCE, MITIGATION AND ADAPTATION
Managing the coast: Who are the stakeholders in the ICZM? (Give 5 examples)
stakeholders in ICZM:
- fishermen
- lab scientists
- conservationists (turtle and bird study and protection)
- locals who live along the coast
- ecotourism employees
99
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA: EVALUATING HUMAN RESPONSES OF RESILIENCE, MITIGATION AND ADAPTATION
Managing the coast: What are the 4 main issues to be addressed?
main issues to be addressed:
- assessment and control of coastal erosion
- development of ecotourism
- planting/replanting mangroves
- building cyclone shelters
100
3.11 RISK AND OPPORTUNITY IN ODISHA, INDIA: EVALUATING HUMAN RESPONSES OF RESILIENCE, MITIGATION AND ADAPTATION
Explain the role that mangroves have had in the management of this coastline/reducing the threat from flooding
- presence of mangroves => 50% more accretion = buffer! (negative feedback cycle)
- mangroves absorb wave energy from storm surges and have saved lives because of it
- previously, areas with 4+km of mangroves had no deaths during a supercyclone
