Coasts Flashcards
3 reasons why our coastlines are important
- Coastal population- 50% of worlds population live on coastal plains
- 1 billion people live on coasts are at risk of flooding
- Economic benefits - 210,000 jobs are provided by coastline activities
The littoral zone is….
Area of shoreline from sea to land - the coastal zone in which sediments are moved around between land, beach and sea.
This zone is subdivided into:
- backshore
- foreshore
- nearshore
- offshore
The backshore is….
The area between high tide and the land
The foreshore is….
The area between high tide and low tide
The nearshore is….
The area between low tide and point where waves break - ‘breaker zone’
The offshore is….
The area of the sea where deposition, transport and erosion no longer affects the coastline - zone is seawards
3 Inputs which affect the coastline:
- Local geology - rock type + structure
- Climate/weather
- Wave size / frequency / type / direction
3 Processes which affect the coastline:
- Longshore drift
- Deposition
- Mass movement
3 Outputs which affect the coastline:
- Erosional landforms
- Coastal management
- Different types of coastline
The 3 different types of coastline is:
- High energy
- low energy
- coastal plains
High energy coastlines are:
Rocky coasts where waves are powerful for the most of the year - erosion land-forms are found
Low energy coastlines are:
sandy coastlines - constructive waves dominate - deposition landforms are found
Coastal plain coastlines are:
Areas of low,flat relief. Can be susceptible to coastal flooding
Other two ways of classifying coasts more broadly:
-rocky coastlines
- coastal plains
Rocky coastlines:
- formed from rock
-cliffs vary in height - sub-aerial processes can dominate and some while marine processes at others
Coastal plains:
- low lying
- low-relief
- wetland and marshes
- poor drainage
- coastal accretion can occur - where coastline moves seawards
Where does coastal sediment come from:
- cliff erosion
- tidal currents
- transport
- rivers
Unconsolidated is….
A sediment that is loosly arranged or unstratifed (not in layers) or whose particles are not cemented together (soft rock)
Put igneous, sedimentary and metamorphic rock in order from weakest to strongest with an example
- weakest - sedimentary - eg sandstone
- strong - metamorphic - eg. marble
- strongest - igneous - eg. granite
4 geological influences on coasts
- Lithology - rock type - permeability
- orientation of strata - concordant/discordant
- Dip angle - seaward dip = vulnerable to mass movement, landward dip = more stable
- Tectonic processes - faults + folds can expose lines of weakness
Lithology can mean any of the following characteristics:
- Strata
- Bedding planes
- Joints
- Folds
- Faults
- Dip
Explain strata
layers of rock
Explain Bedding plane
horiontal cracks
natural breaks in strata, caused by gaps in time during periods of rock formation
Explain Joints
vertical cracks
These are fractures caused by contraction as sediments dry out, or by earth movements during uplift.
Explain folds
Formed by pressure during tectonic activity which makes rocks buckle an crumble - ege lulworth crumple
Explain faults
Formed when stress or pressure to which rock is subjected, exceeds its internal strength (causing it to fracture).
Explain Dip
Refers to the angle at which the rock strata lies (horizontally, vertically, dipping towards sea or land)
Anticlines and syncline
When rocks are under pressure from tectonic activity it will either fault (break during earthquake) or fold (bend and reshape).
Both will cause joints + fissures (cracks) to form which are areas of weakness and can be attacked by wave erosion.
Draw Anticlines and synclines
Draw the following :
1. horizontal bedding
2.landward dip
3. seaward dip
find answers online/in folder
What is a concordant coastline:
When the geology is arranged parallel to the shore
What is a discordant coastline:
When the geology is arranged perpendicular to the shore - at a right angle
What are some key features of a Haff:
- long sediment ridges topped by sand dunes that run parallel to coast
- can see lagoons (a haff) which are created between ridge and shore
What are some key features of a Dalmation:
- mountainous shore
- pebble beaches
- hard rock
What are 3 influences on waves:
- fetch - distance wind blows
- area- sheltered or not
- wind speed
Explain the process that causes a wave to break:
- waves break as our water becomes shallower
- the frictional drag decreases as the wave reaches shallow water and therefore slows down
- The wave still has a lot of energy, as the surface of the wave crashes and releases the energy, causing it to break
Whats the definition of waves :
Waves are the medium through which energy is transferred. They are created by the wind blowing across the surface of the sea.
Destructive waves…..
- more frequent - over 15 per min
- strong backwash
-weak swash
-steep shingle beach
-high energy - can create landforms eg. offshore bars
Constructive waves ….
- less frequent - 8 or less per min
- weak backwash
-strong swash - gently sloping sand beach
- low energy
Transportation along the coast can be seperated into 2 overall types:
- Marine (water)
- Aeolian (wind)
what are the definition of:
1. traction
2. saltation
3.suspension
4.solution
- traction- where boulders are rolled along the sea bed
- saltation - small sediment pieces bounce along the river bed
3.suspension- light sediment is carried/suspended in the water
4.solution- when pieces of sediment are dissolved within the water
depositional coastlines are….
sand dunes ect.
erosional coastlines are….
arch, stack, stump ect.
look at date 20/9/24 at longshore drift annotated image
Defintion of erosion:
The action of surface processes that removes soil, rock or dissolved material from one location and then transports it to another location.
Defintion of weathering:
the decay and disintegration of rock in situ. there are 3 main types of weathering that affect the coast - mechanical, biological and chemical.
Definition of subaerial:
‘under the air’ = existing, occuring or formed in the open air or on the earths surface
What are the 2 types of subaerial processes and a defintion;
- weathering - gradual breakdown of rock on ground surface
- movement of weathered material down a slope as result of force of gravity
What does dynamic equilibrium in a sediment cell mean?
a stabilisation of inputs and outputs
How can humans influence sediment cells?
by managing the supply of sediment.
eg. groynes for trapping sediment and stopping it from moving downstream.
Give 2 factors influencing rates of recession at holderness:
- geology- clay and glacial
- long fetch
What are the reasons of why sea levels are rising:
- result of global warming
- since 1880 global temp increased by 1 degree
- caused ice to melt
- thermal expansion
What are the impacts of rising sea levels:
- coastal flooding and erosion
- habitats and ecosystems destroyed
- farmland destroyed
- businesses flooded- effects local and national econoy
- animals may have to adapt to new conditions
What are the two types of sea level change and their defintions:
- Eustatic change- sea rises or falls
- Isostatic change - land rises or falls
How does isostatic change occur?
- during glacial periods (ice ages) large ice masses caused the land to shrink and fall because of the pressure
- in inter-galacial periods ice has melted and the land rebounds as it does not have the weight of the ice.
- The melting cryosphere also experiences this- anywhere where the water is stored - frozen water eg. ice caps/snow.
What is the evidence for isostatic change?
- fossil beaches and raised cliffs can indicate isostatic rebound.
- they were previously in contact with the waves- which had created erosional features - now above beach and further inland.
What are the 3 factors contributing to isostatic change during interglacial periods:
- thermal expansion
- melting land ice
- albedo effect
Explain thermal expansion:
- the higher the temperature the bigger the volume of water (particals are further apart) sea level rise.
Explain melting land ice:
- (cryosphere) increase water volume = sea level rise
Explain the albedo effect:
- Reduction in the amount of suns heat reflected (off snow-light)
- 96% is reflected
- as snow melts it opens up dark ground and heat get absorbed = higher temperature
What are depressions and how do they occur?
- intense low weather systems
- create less settled weather systems
- occur when fast moving area of cold air moves into a region of warmer air - pushing warm air upwards
- as it rises, air pressure falls
- for every millibar the pressure drops, sea level rises by 1cm.
What are some of the causes of coastal flooding:
- land subsidence
- removal of vegetation
- building sea defences
- storm surges
- climate change
Definition of storm surges:
a short-term change in sea level caused by low pressure + pushing of water by winds.
Name some factors that increase the rates of erosion at a coast:
- wave type - distructive = more erosion
- wave speed
- fetch
- geology along coastline - rock type and orientation of strata
- removal of dune vegetation
- hard engineering - terminal groyne syndrome
- weather systems - storm surges - more distance = gains more power
Some facts on the Holderness coast:
- coastline in the north east of england
- consists of small towns and villages and rural settlements
- one of the fastest eroding coastlines in europe - average 2m per year
- extreme cases -10m per year
What are some reasons to why the Holderness coast is so susceptible to erosion:
- geology - made up of soft boulder clays
- longshore drift- bouler clays erode easily and transported out via longshore drift
- fetch - exposed to wind and waves from north-east with fetch of 300-800km across north sea
What are the key players along Holderness:
- hotel and business owners
- delivery drivers along B1242
- DEFRA and environment agencies
- local counsil
residents
What are some other reasons why the Holderness is at risk:
- increased population
- subsidence - isostatic changes - lead to SLR
- climate change and storm surges
- vegetation removal - natural protection
what are the 2 types of coastal engineering and their definitions:
- hard engineering - involves man - made structures
- soft engineering - designed to work with natural processes
What is a cost benefit analysis (CBA)?
- carried out before a coastal management project to give the go ahead.
What are the 2 types of cost and benefits?
- tangible- where cost and benefits are known and can be given monetary value
- intangible- where costs may be difficult to assess but are important
Look at holderness case study info sheet after lesson 22/11/24 and the sheet after about hard engineering
What is the reasons for management at Hornsea?
- high density urban development
- high population
- lies on soft boulder clay - susceptible to erosion
- local economy is dependent on tourism and recreation
What is hornseas management strategies?
- sea wall
- rock armour to protect sea wall
- wood groynes - trap sediment transported by longshore drift building wide sandy beach
- position of coastline has been artificially fixed to hold the line
What are the effects of the coastal management at Hornsea?
- been effective in stopping erosion along sea front at Hornsea
- but has increased rate of erosion downdrift of defences
What are the conflicts involved in the coastal management at Hornsea?
- increased rate of erosion downdrift has led to loss of caravan pitches
- increased erosion has led to loss of farmland downdrift of the defences
What was the reason for management at Withernsea?
- high density urban development
- high pop
- lies on soft boulder clay- susceptible to erosion
- local economy - dependent on tourism and recreation
What is the management strategies at Withernsea?
- sea wall
- rock armour
- wooden groynes trap sediment and build up beach
- timber groynes replaced and sea wall strengthened in 2017\18
- plan is to hold the line
What are the effects of coastal management in Withernsea?
- effective in stopping erosion along sea front at Withernsea
- but increased rate of erosion downdrift of defences
What are the conflicts involved in coastal management at Withernsea?
- increased rate of erosion downdrift led to loss of caravan pitches
- increased erosion has led to loss of farmland downdrift of defences
What is the reason for management at Mappleton?
- village has around 50 properties
- soft boulder clay cliffs - eroding rapidly - resulting in main road only 50m from cliffs
- the B1242 main road connecting settlements along Holderness coast runs through Mappleton.
What is the management strategies at Mappleton?
- cliff is stabilized by reducing angle and planting vegetation
- rock groynes trap sediment transported by LSD
- rock armour protects base of cliff
- high sandy beach protects cliff
What are some effects from coastal erosion in Mappleton?
- been effective in stopping erosion along sea front
- it has increased rate of erosion downdrift of defences
What are some conflicts involved in the coastal management in Mappleton?
- increased rate of erosion has led to loss of spaces in public car park leading to tourists parking on side of road causing conflict with local residents
- led to farmland and properties downdrift of defencez
What are the hotel and business owners opinion on management?
- mixed opinion on coastal management
- defences put in place protect income
- but tourism has been declining in Withernsea - touridt reported riprap= unattractive
What is DEFRA and environmental agencies opinion on management?
- mixed opinions
- EA prefer soft engineering - tend to be more critical of hard engineering strategies
- particularly groynes at Mappleton and Hornsea - starving spern point of sediment
What are the delivery drivers along the B1242 opinions on management?
- tend to support hard engineering methods as they are more effective in preventing erosion down crucial transport route.
What is the local councils opinion on management?
- similar views to DEFRA
- however they are more likely to take into consideration of local residents and push for more areas to be protected - eg Mappleton - small residential town.
What are the residents opinion on management?
- in favour of any coastal management strategies that will protect their homes
- however some more supportive than others
- at Hornsea - supportive of groynes in place but starves downstream at Mappleton
- but groynes at Mappletom cause starvation at Cowden.
What are 6 sustainable coastal management strategies?
- creating alternative livelihoods before existing ones are lost to the sea
- managing flood and erosion risk where possible or relocating to safe areas
- educating communities to understand why change is needed and how to adapt
- adapting to rising sea levels by relocating alternative building methods and water supplies
- managing natural resources - fish, farmland, water supplies to ensure long- term productivity
- monitoring coastal change and adapting to unexpected change
What is the integrated coastal zone management?
The process of protecting the entire coastal zone, not just the part where waves break and also not just by single communities but rather all players involved.
Case study : Odisha India
what are the 4 management methods in India and their chain of reasoning?
- Managing mangrove forest -> provide jobs for local people -> helps the economy g row through taxation -> mangrove is a natural barrier to erosion
- Assesement of erosion -> protects homes and infrastructure -> saves lives and income, business, homes
- Building cyclone shelters -> prep for tropical storm -> reducing loss of lives/money -> no need to rebuild/reinvest in area
- Eco-tourism -> brings in money -> not damaging environment = spreading positive message -> educates community
Name 4 shoreline management plans and their definitions
- No active intervention - letting nature take its course and allowing sea to erode cliffs and low lying land while not repairing existing defences.
- Hold the line - maintaining the current position of the coastline.
- Managed realignment (retreat) - allowing the coastline to retreat but in a managed way. Includes deliberate breaching of flood barriers and flooding of low quality farmland to create salt marshes.
- Advance the line- extending the coastline out to sea eg. by encouraging the build up of a wider beach using beach nourishment methods or by building groynes.
What is an advantage and disadvantage of no active intervention?
A - free- no money spent
D- literally does nothing - risk to homes lands and lives
What is an advantage and disadvantage to holding the line?
A- reduces erosion going any further - saves homes/ lives
D - can be expensive
What is a advantage and disadvantage of managed realignment?
A- coast effective
D- eventually coastline will get smaller and homes/ infrastructure at risk
What is a disadvantage and advantage to advance the line?
A- soft engineering - environmentally friendly and effective
D- expensive
