Coasts Flashcards
The coastal system is an … System
Open
Inputs in the coastal system
Precipitation
Wind
Fluvial sediment
Flows/processes in the coastal system
LSD
Erosion
Mass movement
Evaporation
Stores and components of the coastal system
Beaches
Sand dunes
Spits
Bars
Outputs of the coastal system
Headlands Bays Wave cut platforms Ocean currents Evaporation RIP tides
Negative feedback of the coastal system
Mass movement decreasing cliff foot erosion
Positive feedback in the coastal system
Coastal management increasing erosion elsewhere
Terrestrial factors influencing the coastline
Tectonics Sun-aerial processes Glaciations Supply of sediment Fluvial processes
Marine processes influencing the coastline
Bionic features eg reefs Wave shape/size Fetch Sea level change Wave direction Tides
Human intervention factors influencing the coastline
Industrial and residential development Sea defences Conservation Tourism and recreation Global warming Pollution
Atmospheric factors influencing the coastline
Winds Precipitation Temperature Solar energy Global warming
Define dynamic equalibrium
A system in dynamic equalibrium has inputs and outputs of energy and matter that balance
Dynamic equalibrium is affected by:
Supply of sand ie conservation
Energy of waves
Sea level change ie global warming
Location of the shoreline eg managed retreat
Define landform
Individual features which are created by coastal processes eg stacks, wave cut platforms, and spits
Define landscapes
The entire area of sea, coastline, and immediate land behind the sea front. Within the landscape are characteristic landforms
Sources of coastal energy
Waves
Wind
Currents
Tides
As with all Earth systems the initial energy input for the coastal system is…
From the sun
How does the sun’s energy cause other forms of energy in the coastal system
It causes different air pressures (due to different rates of heating) which creates wind, this wind then generates waves which are the main form of energy
How is wind formed
Air moving between areas of high pressure to low pressure (along a pressure gradient)
How does the pressure gradient affect wind speed
The steeper the gradient the faster the wind moves
How does the strength of the wind influence wave energy
The stronger the wind the bigger the wave
How does fetch influence wave energy
The shorter the fetch the smaller the wave (less distance to gain energy)
How does the duration of the wind influence wave energy
The longer the wind has been blowing , the longer time the waves have to gain energy
How do waves form
Diagram look it up idk
Why are some areas of the uk subject to more powerful waves than other areas
Fetch is longest in South West and shortest in South East
South West prevailing wind
South West is a high energy coast
South West not heavily eroded due to rock type
Constructive wave components
Low wave
Long wavelength
Strong swash
What are the processes associated with constructive waves
Deposition and LSD
How are constructive waves formed
Distant weather systems
Landforms made by constructive waves
Beaches, spits, and bars
Which waves never reach the back of the beach (backshore)
Constructive
Destructive wave components
Tall in relation to length
Steep beach profile
Strong backwash
What are the processes associated with destructive waves
Erosion Mass movement (cliff erosion and undercutting)
When are destructive waves most common
During winter storms
Features created by destructive waves
Wave cut platforms
Cave
Arch
Stack
What are tides
Periodic rise and fall in the level of the sea caused by the gravitational pull of the sun and the moon
Both the … and … of the tides change on a daily basis based on the position of the sun and the moon relative to the Earth
Time and size
Why are spring tides exceptionally high
The gravitational pull from the sun and moon is in the same direction which means there is more force
Why are neap tides very low
The sun and the moon are pulling in different directions
Why is knowledge of tides essential for coastal management
Tides could go over groynes or sea wall and make them useless
Which process is more evident in high energy coastlines? Erosion or deposition
Erosion exceed deposition
Which process is more evident in low energy coastlines? Erosion or deposition
Deposition exceeds erosion
Where in the Uk are high energy coastlines mostly found and why
Atlantic facing eg Cornwall because there is a large fetch so high energy waves
Landforms associated with low energy coastlines
Sheltered areas eg bays
Beaches and spits
Landforms found in high energy coastlines
Cliffs and headlands
What is the tidal range
How long wave processes can act on a cliff face for
Small range means more focused on the same area for longer and so more erosion
What is tidal current
The horizontal movement of water accompanying the rise and fall of tides
Flood current definition
The incoming tide along the coast and into the bays and estuaries
Define the ebb current
The outgoing tide
When do the strongest flood and ebb current occur
Before or near the time of the high and low tides when water levels are closest to their highest/lowest value
Slack tides definition
The weakest currents occurring between the flood and ebb currents
Where are currents strongest
Near estuary entrances, narrow straits, and inlets
What do large tidal ranges do
Provide energy via tidal currents and transport sediment
What do small tidal ranges do
Concentrated erosion at the cliff base
What are orthogonals?
They show the direction of energy
What causes wave refraction?
The shape of the sea bed means that the waves hit shallower water at different times, shallower water means slower waves
Where is the area of high wave energy? Headland or bay
Headland
Define sediment cell
A stretch of coastline within which sediment movement is more or less contained
Give an example of a sediment cell
Flamborough Head (eastern coast of England)
Sources of sediment
Rivers
Cliff erosion
Offshore sediment
Wind
Where does most of the sediment come from
Rivers
What type of rock does Cornwall have
Tough, igneous granite
Rates of cliff erosion along the Holderness Coast in Lincolnshire can be as high as…
10m/year
How is offshore sediment transported into the coastal zone?
Waves
Tides
Currents
Storm surges
Define geomorphological
Changing Earth - sub aerial and marine processes
What are geomorphological sub-aerial processes
Weathering
Run off
Mass movement
What are geomorphological marine processes
Erosion
Transportation
Deposition
How does geographical location determine the type and rate of weathering
Wildlife - burrowing animals so more physical
Climate
Rock type
Positive feedback example in weathering
If the rate of debris removal exceeds the rate of weathering and mass movement then the latter will increase
Example of negative feedback in weathering
If debris removal is slow more will build up so weathering and mass movement rates will decrease as cannot get to the cliff
Define mass movement
The downhill movement of weathered material under the force of gravity
Define biological weathering
The breakdown of rocks by organic activity I.e. plants, animals
Define chemical weathering
Involves a chemical reaction where salts may be dissolved
Define mechanical/physical weathering
Involves the break up of rocks without any chemical changing taking place
Give examples of biological weathering
Tap roots
Burrowing animals
Water running through decaying vegetation becomes acidic
Give examples of chemical weathering
Carbonation
Oxidation
Solution
Give examples of mechanical weathering
Frost shattering
Salt crystallisation
Setting and drying
What are the types of mass movement
Solifluction Mudflow Run off Landslide Rock fall
Factors affecting the rate of erosion
Lithology Waves Sea defences Discordant/concordat coastline Season Tidal range Geological structure
What are the methods of transportation
Saltation
Solution
Traction
Suspension
Define traction
Large particles like boulders are pushed along the sea bed by the force of the water
Define suspension
Small particles like silt or clay are carried along in the water
Define saltation
Pebble sized particles are bounced along the sea bed by the force of water
Define solution
Soluble materials dissolve in the water and are carried along
What determines the method of transportation of sediment
Size of particle
Energy of waves/water
Another name for LSD
Littoral drift
Deposition in high energy coasts
Small particles are easily transported
Larger material is deposited forming shingle beaches
Deposition in low energy coasts
Even the smallest material deposited forming mudflats and salt marshes
What are the processes of erosion
Hydraulic action Wave quarrying Abrasion/corrasion Attrition Solution/corrosion
Define hydraulic action
The impact on rocks of the sheer force of the water which exerts a lot of pressure on the rock and so weakening it
Define wave quarrying
A braking wave traps air in the cliff, air compressed, water retreats and pressure released so large areas removed
Define abrasion
Eroded material being thrown against the rock by waves (wave cut platforms)
Define attrition
Rocks which are carrying out abrasion are slowly worn down into smaller and rounder particles
Define solution
Dissolving of rocks
Concordant coastline
Parallel to the sea
Example of a concordant coastline
South Purbeck, Dorset
Discordant coastline
Perpendicular to the sea
Example of discordant coastline
East Purbeck, Dorset
What is the cliff profile
The gradient of the cliff
How do sedimentary rocks form
Layers of deposited sediment, either on the beds of ancient oceans or rivers
Sequence leading to stack
Headland Line of weakness Cave Arch Stack
Ridges in beaches
Accumulations of sand in lines where the sediment has been deposited
Swash alligned
Sediment moves up and down the beach with little lateral transfer
Drift alligned
LSD
What are the two types of spit
Compound
Simple
Compound spits
Barbs or hooks on their landward side
Simple spits
Bars of sand without barbs or hooks
What are barbs and hooks?
Secondary wind directions cause different LSD direction
What are tombolos?
form in a similar way to spits but are unique because they join the main land to an offshore island via deposition
Name a famous tombolo
Angel road of Shodo Island, Japan
Name an UK example of a barrier beach
Slapton Sands
Name a non-UK example of a barrier beach
Jupiter Island, Florida
Name an UK example of barrier islands
Scolt Head Islands, Norfolk
Name a non-UK example of barrier islands
Alabama barrier islands, Mississippi
Name an UK example of offshore bars
Hordle Cliff offshore bar
Name a non-UK example of offshore bars
Gulf of Mexico has some
What are sand dunes
Accumilation of sand blown into mounds by the wind
What is an aeolian formation
Formed by the wind
Are sand dunes deposition landforms
Not officially because they are formed by deposition from the wind not the sea
What do sand dunes need to form?
Flat beach
No secondary wind direction
Types of sand dune
Embryo dune Fore dune Main ridge Grey dune Dune slack Dune health Mature dune
What are human threats to sand dunes
Industrial pollution Agricultural pollution Dredging Shipping Grazing
What component are marshes within the coastal system
Stores
How are mudflats created
The deposition of fine salts and clays in sheltered low energy coastal environments such as esturies
What are salt marshes
Areas of coastal grassland that is regularly flooded by seawater
Required conditions for mudflats to form
Low energy Deposition Sheltered area No strong tides or currents Where salt and freshwater meet
Define pioneering species
The first plants to colonise an area e.g. eelgrass and cordgrass
Define flocculation
Mud deposited close to high-tide line, dropping out of the water by flocculation where tiny particles of mud stick together such that their combined mass enables them to sink to the sea bed
Define halophytes
Plants that tolerate salt water - have adapted
Eustatic change
A global change in sea level resulting from a fall or rise in the level of the sea itself
Isostatic change
Local changes in sea level resulting from the land rising and falling relative to the sea
Causes of sea level rise
Thermal expansion and melting land ice
Thermal expansion
Where the volume of water increases as it gets warmer
When did the last glaciation end?
10 000 years ago
What leads to a submergence coastline?
Land sinks and sea level rise
What leads to an emergence coastline?
Land rise and sea level fall
What is a rias?
A submergence coastline feature, submerged river valleys.
Give an example of a rias?
Dartmoor
What are marine platforms/terraces?
A wave cut platform which is higher than sea level and at the base of a relict cliff
Give an example of a marine platform/terrace
Examples found in Scotland
What are dalmation coasts?
A series of river valleys next to the coast which have been filled with water leaving parallel ridges as islands
What are relict/fossil cliffs?
Emergent coastline feature
Weathering affects it not coastal erosion
An old cave showing features of caves etc
Give an example of a relict/fossil cliff
Isle of Arran, Scotland
What are fjords?
When a glacier retreats and the sea fills the valley floor
Submergence coastline feature
Give an example of a fjord
Sognefjord, Norway
What is a raised beach?
Emergent feature
Former wave cut platforms and their beaches are higher than the present coastline
Give an example of a raised beach
Isle of arran, Scotland
What is subsistence?
Coastal areas sinking due to excess ground level extraction which has the effect of making the sea level higher
…% of the UK manufacturing industry lies close to the coast
40
…million people live within the coastal zone
16.9
Why does the coastline need managing?
Coastal erosion
Coastal flooding
Failure of former defences
What’s a hold the line management strategy?
Maintain current defences or build new ones to ensure coastline stays where it is
What’s an advance the line approach?
Build new defences seaward of existing
What’s a retreat the line (managed retreat) approach?
Allow the coastline to retreat due to flooding and erosion but closely manage rate and location of this retreat
The do nothing approach
Low value areas lift to natural coastal processes as not deemed viable to spend on defences
Social things to consider when planning management strategies
Number of people directly impacted
History and culture
Employment/unemployment levels
Political things to consider when planning management strategies
Voter opinion/importance
Why pays? - local/national government
relationships with other areas
Economic things to consider when planning management strategies
Value of infrastructure and housing
Cost of businesses in the area
Cost of defences
Environmental things to consider when planning management strategies
Valuable ecosystem
Is the environment common? (salt marshes are rare)
Pollution the defences will cause
Will there be damage elsewhere
Hard engineering strategies
Sea walls Groynes Gabions Revetements Barrages Offshore reefs
Soft engineering strategies
Beach nourishment Dune regeneration Managed retreat Land-use management Do nothing
What is a sea wall
At the foot of a cliff or at the top of a beach, usually have a curved face to reflect waves back at into the sea
Advantages of sea walls
Effective prevention of erosion
They often have a promenade for people to walk along
What are groynes
Built at right angles to the coast, they trap sediment being moved up the beach
Advantages of groynes
Work with natural processes to build up the beach with increases tourist potential and protects the land behind it
Not too expensive
What are revetements
Sloping structures placed at the foot of the cliff or top of beach, they break up the waves energy
What are offshore reefs
A partly submerged rock barrier, designed to break up the waves before they reach the coast
What is a cost benefit analysis?
(Carried out before a coastal management project is given the go ahead) it’s where costs are forecasted and compared with the expected benefits
Define tangible costs
Where costs and benefits are known and can be given a monetary value
Define intangible costs
Where costs may be difficult to asses but are important eg visual impact
Historically, cost Benifit analysis were not conducted what issues may this have caused?
Other areas nearby may be affected
It could be a waste of money
Did not consider the intangible costs
Define soft engineering
Works with nature and natural systems to protect the coast
Define hard engineering
Making a physical change to the coastline using man made materials and/or structures
How many SMPs (shoreline management plans) did the government create and what does this number represent?
22 (number of sediment cells)
What is the purpose of SMPs?
Their purpose is to avoid affects further down the coastline when protecting one stretch
What are ICZMs?
Integrated coastal zone management (they focus on sustainability and desires of different stake holders)
What are the different stakeholder groups in ICZMs?
Coastal residents Local council/government National government Conservation groups Local businesses Tourists
Why are ICZMs more sustainable?
Focuses more on the future (economic and environmental effects) and by collecting information they can adapt to any changes and can make improvements
What are some arguments for not protecting to coast at all?
Cost benifit analysis
Environmental impact now and future
Land may not be at risk
May impact other areas negatively
What local coastal environment did I study?
Slapton sands
What are the processes found at slapton sands?
LSD
Deposition
Erosion
Evidence of coastal processes at work in slapton sands:
Barrier beach Beach Stack/stumps Cove Wave cut platform Headland/bay
What is the name of the barrier beach found at slapton?
Slapton sands
What is the name of the beach at slapton?
Beesands
What is the name of the headland/bay at slapton?
Start point and start bay
What is the name of the stacks/stumps at slapton?
Dancing beggars
What is the name of that the cove at slapton?
Redlap cove
What is the name of the wave cut platform at slapton?
Limpet rocks
What is the fat place study I did and why?
Odisha, India because it has unique characteristics and setting
Where is odisha?
East coast of India
Boarding the Bay of Bengal
What type of climate does India have?
Seasonal ie monsoons
Odisha is India’s 9th largest state by…
Area
Odisha is India’s 11th largest state by…
Population
How long is odisha’s straight coastline?
480km
Describe odisha’s unique ecology:
Endangered olive ridley turtles
1435km^2 of mangrove forest (rare)
Chilika Lake which is salty but fresh in monsoons
What is the dominant process occurring at Odisha?
Deposition so it’s a low energy coast
How many rivers have mouths on the Odisha coastline?
6 so most of the sediment is fluvial
Risks/difficulties in protecting the odisha coastline:
Increased rates of erosion
Vulnerable to storms, tsunamis, and rising sea levels
14.4% stable
Why has there been increased rates in erosion in odisha?
Both natural and human factors (ie protecting infrastructure as many people live by the coast so rely on it)
Rewards/benefits of protecting odisha’s coastline:
Potential for offshore generating of electricity
35% of coastline has resources which can be sold (eg metal deposits)
Fishing and agriculture industry vital to locals
Chilika Lake Bird Sanctuary has 159 species of bird
How does planting of mangroves become a defence? (Odisha)
Make waves loose energy
Roots hold sediment together which stabilises the coast from erosion etc
Why does a 14.4% stability in odisha’s coastline make it difficult to protect?
Difficult to decide which strategy
Long term investment is risky
Difficult to predict changes
Where is Slapton Sands
Devon
Length and age of seawall at Torcross
319 m it was built in 1979 rebuilt in 2000 by the environment Agency
Height and age of sheet piling topped with concrete rocks just north of Torcross
143 m and 1979
Where is the 795 meter revetment built in 1979
Between Torcross and the car park
What protects the a 379 Road at Slapton Sands
Rock armour
Why has beach nourishment not been used at Slapton Sands
£1.14 million to maintain so too expensive
What future defences could be used at Slapton Sands
Shingle recycling
How much of the odisha coastline is being eroded
36.8%
What is affected by the accelerated rates of erosion at odisha in recent years
Habitats and coastal agriculture
Hazards associated with the Odisha area
Tsunamis and tropical storms
What is the long-term threat to the Odisha coastline
Sealevel rise
What has been exploited in Odisha
Fish and minerals impacting the livelihoods of coastal populations
Why do Tourists go to odisha
For the beaches and wildlife sanctuaries
What sort of energy production is there a huge potential for at odisha
Wave offshore wind and tidal energy
Percentage of the Odisha coastline is laden with mineral and heavy metal deposits
35%
