Coasts Flashcards
What is the littoral zone
The wider coastal zone including adjacent land areas and shallow parts of the sea just offshore
What four zones can the can the littoral zone be divided into
Backshore: This is the inland limit of the beach and the waves only reach this area during exceptionally high tides
Foreshore: This is the area between the high tide and the low tide mark
Nearshore: The area of shallow water beyond the low tide mark, within which friction between the seabed and waves distort the wave sufficiently to cause it to break.
Offshore: The area of deeper water beyond the point at which waves begin to break. However, friction between the waves and the sea bed may cause some distortion of the wave shape
Explain the three different types of coastal landscape
Rocky, cliffed coastline
Areas of high relief varying from a few metres to hundreds of metres in height
Usually form in areas with resistive geology, in a high energy environment, where erosion is greater than deposition
At low tide the foreshore is exposed as a rocky platform (wave-cut platform)
Sandy coastline
Areas of low relief with sand dunes and beaches, that are much flatter
Usually found in areas with: less resistant geology, a low energy environment, where deposition is greater than erosion and there are constructive waves
At high tide the sandy beach in inundates, but vegetated dunes are not
Dune vegetation plays a crucial role in stabilising sandy coastlines and preventing erosion
Estuarine coastline
These are areas of low relief with salt marshes and mudflats (estuaries)
They form in: river mouths, low energy environments and where there is less resistant rock
Estuaries are usually exposed at low tide, but inundated at high tide
This type of coastline gradually transitions from land to sea
What are sub-aerial processes
This refers to the processes of weathering and mass movement
What are the three factors involved with sub-aerial processes
Weathering: The chemical, biological and mechanical breakdown of rocks into smaller fragments and new minerals
Mass movement: landslides slumps and rocks falls, all of which move material downslope under the influence of gravity.
Surface run-off: water, usually during heavy rain, flowing down the cliff face and causing erosion of it.
What factors can determine a rocks resistance to erosion and weathering
How reactive minerals in the rock are when exposed to chemical weathering; calcite (found in limestone) can be weathered by solution, whereas quartz (found in sandstone) is not subject to chemical weathering
Weather rocks are clastic (sedimentary rocks like sandstone, made of cemented sediment particles) or crystalline (igneous and metamorphic rocks, made of interlocking crystals); the latter are more erosion resistant
The degree to which rocks have cracks, fractures and fissures, which are weaknesses exploited by the forces of weathering and erosion
What are coastal plains
These are low-lying, low energy, low-relief areas close to the coast
Describe coastal plains
- Many coastal plains contain wetlands and marshes because they are only just above sea level and poorly drained sue to the flatness of the landscape
- They are often formed in two ways: the result of a fall in sea level, or the coastal accretion where the coastline moves seaward due to the deposition of sediment from land
- They are maintained in dynamic equilibrium by the deposition of sediment from river systems and the erosion by marine action at the coast
What is coastal accretion
The deposition of sediment at the coast and the seaward growth of the coastline, creating new land. It often involves sediment deposition being stabilised by vegetation
What is Dynamic equilibrium
The balanced state of a system when inputs and outputs balance over time If one element of the system changes because of an outside influence, the internal equilibrium of the system is upset and other components of the system change
Describe Concordant coastlines and the features found at them
- Concordant coasts have geological strata that runs parallel to the coast
- The outer hard rocks (e.g. granite) provides a protective barrier to erosion of the softer rocks (e.g. clays) that are further inland
- Sometimes, the outer hard rock is punctured, this allows the sea to erode the softer rocks behind it to erode\
- Subsequently, a cove is produced (a circular area of water with a relatively narrow entrance from the sea)
Explain two examples of Concordant coastlines
Coast of Dalmatia, Croatia, Adriatic Sea
- Geology is limestone
- It has been folded by tectonic activity into
a series of anticlines and synclines that
trend parallel to the modern coastline - This underlying structure has been
drowned by rising sea levels to create a
concordant coastline of long, narrow
islands arranged in lines offshore
Lulworth Cove, Dorset
- The outer hard rock is limestone
- The sea has broken through this barrier
and easily eroded the clays behind it - A chalk cliff face at the back of the cove
slows further erosion - This has allowed the formation of a cove
Describe Discordant coastlines and the features found at them
- Form when different rock strata intersect
the coast at a perpendicular angle - The differing erosion leads to the
formation of headlands and bays - Less resistant rocks are eroded to form
bays whereas more resistant geology
remains as headlands
Why is there little erosion at discordant coastlines?
In deep water wave crests are parallel
As waves approach the shallow water offshore of a headland they slow down and wave height increases
In bays, wave crests curve to fill the bay and wave height decreases
The straight wave crests refract, becoming curved, spreading into out in bays and concentrating on headlands
The overall effect of wave refraction is to concentrate powerful waves at headlands (meaning greater erosion) and create lower, diverging wave crests at bays, reducing erosion
Explain two examples of discordant coastlines
Dorset Coastline
- The limestone is resistant to erosion; then
to the north at Swanage bay the rock
type is softer greensand - North of Swanage, the chalk outcrop
creates the headland which includes Old
Harry Rocks
West Cork coast of Ireland
- Rock strata that include: Limestone,
Mudstone and sandstone meet the
coastline 90 degrees in parallel bands
- Weak rocks have been eroded, creating
elongated, narrow bays, whereas more-
resistant rocks for headlands
- Especially resistant areas remain as
detached islands
What influences a Cliff profile
Cliff profiles are influenced by several different aspects of geology – three characteristics are dominant
Geological structures such as dip, faulting,
joints and folding
Explain how dip influences the features of a Cliff profile
Dip refers to the angle of rock strata in relation to the horizontal
- There are four types of dip:
1. Horizontal dip – vertical profile with notches reflecting strata that are more easily eroded
2. Seaward dip (low angle) –sliders down the dip slope
3. Seaward dip (high angle) – profile may exceed 90 degrees producing areas of overhanging rock; very vulnerable to rock falls
4. Landward dip – steep profile of 70 to 80 degrees producing a very stable cliff with reduced rock falls
Explain how faulting influences the features of a Cliff profile
- Represents major weaknesses within rock
layers (cracks in crust) - Either side of a fault line, rocks are often
heavily fractured and broken and these
weaknesses are exploited by marine
erosion
Explain how jointing influences the features of a Cliff profile
- Occur in most rocks, often in regular
patterns, dividing rock strata up into
blocks with a regular shape
Explain how Folding influences the features of a Cliff profile
- Folding occurs due to crust compression
- Horizontal strata can be folded into a
series anticlines and synclines
What are the three different types of rock
- Igneous
- Metamorphic
- Sedimentary
Describe igneous rocks giving examples
Granite
Basalt
Dolerite
- Erode VERY SLOWLY
- Igneous rocks are formed from cooled
magma - They are crystalline; the interlocking
crystals make for strong, hard erosion-
resistant rock - Igneous rocks such as granite often have
few joints, so there are limited
weaknesses that erosion can exploit
Describe metamorphic rocks giving examples
Slate
Marble
- Erode SLOWLY
- Crystalline metamorphic rocks are
resistant to erosion - Many metamorphic rocks exhibit a feature
called foliation where crystals are all
orientated in one direction, which
produced weaknesses - Metamorphic rocks are often folded and
heavily fractured, which are weaknesses
that erosion can exploit
Describe sedimentary rocks giving examples
Sandstone
Limestone
Shale
- Erode MODERATE to FAST
- Most sedimentary rocks are clastic and
erode faster than crystalline igneous and
sedimentary rocks - The age of sedimentary rocks is
important; geologically young rocks tend
to be weaker - Rocks with many bedding places and
fractures; such as shale, are often the
most vulnerable to erosion
What is pore water pressure and how can it weaken the structures of rocks
The pressure water experiences at a particular point below the water table due to the weight of water above it
Permeable rocks allow water to flow through them – which can weaken rocks by removing the sediment that binds the rock together – it can also create high pore water pressure within cliffs, which can affect their stability.
What are the three types of coastal vegetation that can protect a coastline from erosion
Coastal sand dunes
Coastal salt marshes, found in many river estuaries
Coastal mangrove swamps
What are Halophytes
Plants that can tolerate salt water, either around their roots, being submerged at high tide or salt spray from the sea
What are Xerophytes
Plants that can tolerate very dry conditions, such as those found on coastal sand dunes where the sandy soil retains very little water due to drainage
What is the importance of Embryo dunes in protecting the coastline
- Embryo dunes pioneer plants
- They stabilise the mobile sand – reduce
wind speeds at the sand surface allowing
more to be deposited – add dead organic
matter to the sand, beginning the process
of soil formation - They alter the environmental conditions
from harsh, salty, mobile sand to an
environment that other plants can
tolerate - They lead to the development of plant
colonisation - Grey dunes were once embryo dunes, but
due to plant colonisation, have grown
upwards
What is the importance of Marram grass in dune succession
- Sand dune succession relies on
specialised plants such as marram grass - Marram grass has tough, long and flexible
wavy leaves that are designed to limit
water transpiration - Marram grass has roots up to 3m long that
can tap water far below the surface and
can tolerate temperatures of up to 60
degrees centigrade
What is the importance of salt marsh succession in reducing flooding
- Bare mud, hosts species of algae
- Pioneer plants which colonise mud flats
- Taller plant species from later serel stages
can be seen - The salt marshes form and gradually
slopes towards the shore, because plants
trap sediment on incoming tides, which is
deposited
How does the wave react at the shore?
When they reach the shore, forward movement starts to occur, which, as the depth is less than the wavelength - the base of the wave is slowed down by friction against the sea floor and the wave crest topples over and breaks onto the shore.
What effects the size of the wave
- The size of a wave depends on a number
of factors including: Strength of the wind,
duration the wind blows for, water depth
and wave fetch
Describe constructive waves
- Have a low wave height and a long wave
length - They are gentle, flat waves with a string
swash but weak backwash - The strong swash pushes sediment up
the beach, depositing it as a (berm/ridge
of sediment) at the top of the beach
Describe destructive waves
- Have a very high wave height and a short
wavelength - Common during storms
- Have a strong backwash that erodes the
beach material and carries it offshore,
creating an offshore ridge
What is beach morphology
The shape of the beach, including its width and slope and features, such as berms, ridges and runnels. It also includes the type of sediment found at different locations
What are the four different types of wave type that influences beach morphology
Hydraulic Action
Waves crash against rocks and compress air in the cracks, adding pressure. Repeated compression widens the cracks and causes rocks to shatter
Corrosion
Water dissolves minerals in the rocks (particularly limestone) and washes it away
Abrasion
Sediment picked up by breaking waves is thrown against the cliff face
The sediment acts like a tool on the cliff – chiselling away at the surface and gradually wearing it down
Attrition
Eroded particles in the water collide with each other and break into smaller fragments
What influences how sediment is transported
- Sediment is transported along the
coastlines by currents - Sediment transformation is influenced by
angle of attacks depending on wind
direction, tides and longshore drift
(current flowing at angles to the coast,
transporting material through the actions
of swash and backwash)
What are the four different processes of sediment transport
Traction: Sediment rolls along, pushed by waves and currents
Saltation: Sediment bounces along, either due to the force of water or wind
Suspension: Sediment is carried in water columns
Solution: Dissolved material is carried in the water as a solution
What depositional landforms are formed as a result of sediment transport deposition
- Beaches
- Spits
- Bars
- Barrier beaches
- Tombolo
- Cuspate Foreland
Describe the formation of a beach
Found on coasts between the high-water mark and the low water mark. They form due to constructive waves depositing sand and shingle
Describe the formation of a spit
Beaches which stick out at sea.
They form at sharp bends on coastlines where longshore drift transports sand and shingle past the bend and deposits it in the sea.
Strong winds can curve the spit (called a recurved spit) and plants can grow bashing the spit where waves cannot reach.
Describe the formation of a Bar
Form when a spit joins two headlands together, cutting of the sea from the water trapped between the bar and coastline. This forms a lagoon.
Describe the formation of a barrier beach
Sand or shingle bar above high tide, parallel to the coastline and separated from it by a lagoon
Describe the formation of a tombolo
A spit connected to the mainland, an example being Chesil Beach
Describe the formation of a Cuspate Foreland
Created by longshore drift where sand and shingle deposits extend outward from the shoreline in a triangular shape
What are sediment cells
- Long stretches of coastlines operate as
sediment cells - Sediment cells operate as a system with
inputs, transfers and outputs of sediment.
Under natural conditions the systems
operate in a state of dynamic equilibrium
with sediment inputs balancing outputs to
sinks. - For short periods of time a sediment cells
equilibrium state may be disrupted but will
tend to return to balance over time - Negative feedback mechanisms help
maintain the balance by pushing the
system back towards equilibrium
Describe the three aspects within a sediment cell
Sources: Places where sediment is generated, such as cliffs or eroding sand dunes; some sources are offshore bars
Transfer zones: Places where sediment is moving along the shore through longshore drift and offshore currents; beaches, parts of dunes and salt marshes perform this function
Sinks: locations where the dominant process is deposition; depositional landforms are created including spits and offshore bars
What are the three different types of weathering
- Weathering can either be mechanical,
chemical or biological - Weathering contributes to rates of coastal
recession in a number of ways - Weathering weakens rocks, making them
more vulnerable to erosion or mass
movement processes.
Describe two types of Mechanical weathering
Freeze Thaw
Water expands by 9% in volume when freezing, exerting a force within cracks and fissures; repeated cycles force cracks open and loosen rocks.
Salt Crystallisation
The growth of salt crystals in cracks and pore spaces can exert a breaking force, although less than for freeze-thaw.
Describe the three different types of Chemical weathering
Carbonation
The slow dissolution of limestone due to rainfall
Hydrolysis
The breakdown of minerals to form new clay minerals, plus materials in solution, due to the effect of water and dissolved CO2
Oxidation
The addition of oxygen to minerals, especially iron compounds, which produces iron oxides and increases volume contributing to mechanical breakdown
Describe the two different types of Biological weathering
Plant roots
Trees and plant roots growing in cracks and fissures forcing rocks apart
Rock boring
An important process on vegetated cliff tops that can contribute to rockfalls
Explain mass movement
- On some coastlines, mass movement is
the dominant cause of cliff collapse - There are a number of different types of
mass movement: Blockfall, rotational
slumping, and landslides.
What landscapes are formed as a result of mass movement
Rotational scars: Material deposited from rotational slumping
Talus scree slopes: The loose debris accumulated at the foot of the cliff
Terraced Cliff Profiles: Eroded rocks create ridges within the cliff
What is Eustatic sea level change
Occurs when ice on land melts and returns to the ocean, increasing the volume of the water present in the sea.
Usually this is accompanying by thermal changes which primarily melts land ice.
What is Isostatic sea level change
Occurs from the downward movement of land, causing localised sea level rise.
Land can be stressed downward from post glacial adjustments, subsidence (sinking of land) and accretion (accumulation of layers pushing down on the earth)
What is an Emergent coastline and give an example
- Emergent coasts are a result of local
tectonic uplift of the land surface or a fall
in the elevation of sea level because of a
reduction in the water volume of ocean
basins. - Quite often, emergent coasts have rocky
coastlines with cliffs and nearly flat
platforms that extend inland where older
coastal plains have been tectonically
raised and are now elevated above the
modern land and water interface - An example of an emergent coastline,
because of its proximity to an active plate
tectonic margin, is the west coast of
North America.
What is a Submergent coastline and give an example
- Submergent Coasts are those that have
been flooded by ocean waters because of
a relative rise in the elevation of sea level
at that location. - The rise in sea level can be either the result
of an increase in the volume of water in the
ocean basins or the result of the land surface
sinking, both of which create an apparent
rise in the elevation of sea level. - A common feature of submergent coastal
zones is river valleys or glacially-carved
valleys that have been flooded by ocean
water. - The Chesapeake Bay of the eastern United
States is an example of a submergent
coastline
What are the main factors that cause rapid coastal retreat
Long wave fetch and large, destructive
ocean waves
Soft geology
Cliffs with structural weaknesses such as
seaward rock dip and faults
Cliffs that are vulnerable to mass
movement and weathering, as well as
marine erosion
What human factors can influence rapid coastal retreat
Removing sediment from coastal sediment cells can have severe consequences for erosion
Coastal defences which cause the acceleration of erosion in other areas
Describe and explain the reasons for rapid coastal retreat and the effects of this on the coastline in Holderness
- Holderness is a coastline that is 61km
long in East Yorkshire - It is the fastest eroding coast in Europe
- In some places like Cowden it has been
eroding at 10m per year in recent timesGeology
- The cliffs on this coast South of Flamborough Head are
mainly till/boulder clay and this is easily eroded by corrosion,
corrosion and hydraulic action. - It is prone to slumping and mass movements when wet.
- Narrow beaches – do not provide a lot of protection for the
cliffs. - Made of chalk which dissolves when eroded rather than
making sand for the beach.Powerful waves
- The fetch is long- all the way from the Arctic Ocean
- This causes destructive waves – with large wave height and high frequency crash on the cliffs. Many storms increase their action. • Weathering – physical, chemical and biological weathering
Deep Sea Floor
- The sea floor is deep so there is less friction to slow down
the wave - Low pressure weather systems pass in from the North Sea
Effects on coastline
- Around 30 villages have been lost to the sea since Roman
times - Property prices along the coast have fallen dramatically due
to risk of erosion - This accounts for 25% of Britain’s gas
- 80,000 square metres of Britain’s best farmland lost per year
which has a huge effect on farmer’s livelihoods
Why can flooding outweigh the risk of erosion in some populated coastlines
- On many populated coastlines the threat of flooding
outweighs the risk from erosion - This is because, many people live on low-lying coasts that
are only a few meters above sea level - These areas include:
Coastal plains, such as the east coast of the USA
Estuaries, such as those of the rivers Thames, Severn and Tees in the UK
River Deltas, such as the Nile and Mississippi
Describe the Maldives coastal risk case study
- The Maldives in the Indian Ocean are at risk of rising sea
levels - Its highest point in the country is mete 2.3m above sea level
- The Maldives has a population of 340,000 people spread
out across 122 islands - A sea level rise of just 50cm would mean the Maldives
losing 77 percent of its land area - The capital Male, is ringed by a 3m high sea wall
- Hullmale is a new artificial island built from coral and
sediment dredged from the seabed between 1997 and 2002
at a cost of US$32 million – which is a full metre higher than
Male
How are storm surges caused
- Most coastal flooding is caused by storm surges
- This can be caused by a depression in the mid-latitudes or a
tropical cyclone in areas just north and south of the equator
Describe the 1953 North Sea storm surge case study
- The 1953 North Sea flood was a major flood caused by a
heavy storm - The floods struck the Netherlands, Belgium, England and
Scotland. - A combination of a high spring tide and a severe European
windstorm over the North Sea caused a storm surge - The combination of wind, high tide and low pressure had the
effect that the water level exceeded 5.6 metres above mean
sea level in some locations. - The flood and waves overwhelmed sea defences and
caused extensive flooding. - In England, 307 people were killed in the counties of
Lincolnshire, Norfolk, Suffolk and Essex - As a result of the widespread damage, the Netherlands
particularly, and the United Kingdom had major studies on
means to strengthen coastal defences. - The UK constructed a storm surge barrier on the Thames
River below London, as well as one on the Humber estuary.
Describe the Bangladesh storm surge case study
- Locations that are in the path of tropical cyclones are
especially vulnerable to storm surges - Bangladesh is especially vulnerable to the impacts of
tropical cyclones for a number of reasons:
Bangladesh is a very low lying 1-3 metres above sea level
Incoming storm surges often combine with outflowing river
discharge – meaning river flooding and coastal flooding
combine
Intense rainfall from tropical cyclones
Deforestation of the mangrove has removed vegetation that once stabilised coastal swamps - The 1970 storm surge killed 300,000-500,000 with wave
height over 10m - $US 90 million in damages - The 2007 storm surge killed 15,000 with a wave height of
3m and caused $US1.7 billion in damages
What issues is climate change creating
- Climate change is likely to cause an increase in extreme
weather, the frequency and magnitude of storms whilst
contributing to sea level rise
Explain the three costs of rapid coastal recession
Economic – costs include the loss of property in the form of homes, businesses and farmland
Social – costs are impacts on people, such as the costs of relocation and loss of jobs
Environmental – impacts include the loss of coastal ecosystems and habitats; these are almost impossible to quantify financially but are likely to be small anyway because erosion is part of the natural coastal system to which ecosystems are adapted
Give two examples of the costs of rapid coastal recession
- Repairing the damaged section of the South Devon Main line
railway in 2015 cost 35 million – Estimates of the cost of to
businesses in the South West were put between 60 million
– 1.2 billion - On the Holderness coast – coastal erosion has caused
falling property values; loss of access as roads, paths and
steps down to beaches disappear; loss of amenity value as
the coastline is visually scarred by collapsing roads,
abandoned properties and warning signs
How is global warming threatening; Maldives, Tuvalu and Barbados
- Tuvalu’s highest point is 4.5 metres above sea level, and
most land is 1 to 2m above sea level - Around 80 percent of people in the Seychelles live and work
on the coast - Many are fringed by coral reefs, which act as natural coastal
defences against erosion, however, rising ocean
temperatures is threatening their existence. - They all have high population densities and very limited
space, so there is no opportunity for relocation - They have small and narrow economies based on fishing
and tourism which can easily be disrupted
Evaluate the different hard engineering management techniques
Rip-Rap
- Large igneous or metamorphic rock boulders
- Break up and dissipate the wave energy
- Reduced wave energy
Rock breakwater
- Large igneous or metamorphic rocks
- Forces the wave to break offshore, rather than at the coast reducing wave energy
- However, can interfere with longshore drift
Sea wall
- Concrete with steel reinforcement and deep-piled foundations - A physical barrier against erosion
- Modern sea walls are designed to dissipate the energy
- However, can cause destruction of the natural cliff face and
foreshore environment. If reflective – can reduce
beach volume
Revetments
- Stone, timer or interlocking concrete sloping structures, which
are permeable
- To absorb wave energy and reduce swash distance by
encouraging infiltration
- Reduced wave power
- Can encourage deposition and may become vegetated
Groynes
- Vertical stone of timber fences built at 90 degrees to the coast - To prevent longshore movement of sediment, and encourage
deposition, building a wider beach
- Deposition and beach accretion
- Prevention of longshore drift, sediment starvation and increased
erosion down drift
Evaluate the different soft engineering management techniques
Beach nourishment
- Involves artificially replenishing the beach
- Done to replace sediment lost by erosion
- To enlarge the beach so that it dissipates wave energy.
- To increase the amenity value of the beach by adding fresh
sand
- However, Ongoing costs are high – new sediment is required
every few years
Cliff stabilisation
- Using rock armour at the toe of the cliff and using water pipes to channel groundwater out of the cliff
- Useful in areas where it is the stability of the rocks that is causing coastal recession
- It can be costly
Dune stabilisation
- Wooden wallboards are introduced to keep people off the
dunes – education boards to encourage understanding
– Fences used to reduce wind speed and encourage sand
deposition
- Sand dunes are an effective coastal defence – where they
fringe the coast, they not only absorb wave energy from coastal
erosion but also protect low-lying areas from coastal flooding.
- However, the cost of these methods are low compared to hard
engineering
Evaluate the Abbot Hall Farm sustainable management case study
- Abbott’s Hall farm in Essex is part of the Thames gateway - It
is part of the Blackwater estuary - The salt marshes here are going to be protected and
extended as sustainable coastal management - The sea has been allowed to breach the seawall to convert
84 hectares of farmland back to saltmarsh - This will act as a
natural form of defence for the land behind it - If sea levels rise as expected the salt marsh will migrate
inland naturally - Marsh birds like Brent geese and salt
marsh plants like sea lavender will benefit greatly - Several groups support this decision to allow coast to retreat
the line with new sea walls established further back etc
What are the four major policies debated by the UK government in terms of coastal management
No Active Intervention: No investment in defending against
flooding or erosion. The coast is allowed to erode landward
Hold the Line: Build or maintain coastal defences so that
the position of the shoreline remains the same over time
Managed realignment: Allow the coast to move naturally, but
manage the process to direct it in certain areas
Advance the line: Build new coastal defences on the
seaward side of the existing coastline
Evaluate how Holderness is managing the issue of coastal retreat
Actions
- Along the coast - 11.4km out of 61km currently protected by
hard engineering - Bridlington protected by 4.7km of sea wall as well as timber
groynes - Hornsea village protected by concrete sea wall, timber
groynes and rip rap - Mappleton – in 1991 two rock groynes and 500m long
revetment were built, they cost £2 million and were built to
protect the village and the B1242 coast road - Withernsea – groynes, sea wall have been built and rip rap
placed in front of all when damaged in severe storms in 1992
Impacts
- Groynes trap the sediment but down the coast the erosion
increases e.g. downdrift of Mappleton the cliffs in the South
are eroding and Cowden farm may fall into the sea - Protection is encouraging bays to form, and this may
increase pressure on headlands and it may be too
expensive to protect them - Many of these schemes are unsustainable
Management in the Future
- Shoreline Management Plan (SMP)for Holderness for next
50 years recommends holding the line in some places e.g.
(Bridlington, Withernsea, Mappleton and Easington Gas
Terminal) where there are villages and industry - Do nothing in more unpopulated stretches – unpopular with
locals - Coastal realignment of businesses e.g. Caravan parks move
further inland – but should they be financially compensated? - Sea wall proposed at Easington gas work – would cost £4.5
million but would eroded Easington more (where 700
people live) If longer sea wall to protect both would cost £7
million • Offshore reefs of tyres suggested – but would
these harm the environment?
What is integrated coastal management
- ICZM means adopting a joined-up approach across different
stakeholders in coastal areas in order to harmonise policies
and decision making - In practice this means that coastal management must:
- Plan for the long term, involve stakeholders, try to work with
the natural processes and adopting ‘adaptive management’
Define Hard Engineering schemes
Hard engineering methods are forms of coastal flood defences which mitigate the risk of flooding and coastal erosion and the consequential effects.
Hard engineering methods are often used as a temporary measure to protect against coastal flooding
as they are costly and only last for a relatively short amount of time before they require maintenance.
However, they are very effective at protecting the coastline in the short-term as they are
immediately effective as opposed to some longer term soft engineering methods.
But they are often intrusive and can cause issues elsewhere at other areas along the coastline.
Case Study: Rossall and Anchorsholme, Lancashire
Hard Engineering
The £63million coastal defence scheme was officially opened in June 2018 and is designed to protect
and reduce the risk of flooding to 7500 homes’ along with the town’s tramway, schools and hospitals.
The project was led by Wyre Council, the Environment Agency and Balfour Beatty and is made up of two kilometres of sea walls which have been designed to hold back major storm waves from the Irish Sea for the next 100 years.
The walls have also been designed to protect against the effects of future climate change and sea level rise.
The scheme has improved the local environment by creating a new ecology park on the landward side of the defences, increasing biodiversity, visual aspect and
environmental footprint.
How much does Agriculture provide to the economy
Overall, agriculture contributed around £24 billion of revenues to the economy
How much does coastal recession cost to the economy each year
Flooding, and managing it, cost the UK around £2.2 billion each year: we currently spend around £800 million per annum on flood and coastal defences
Shoreline Management Plan – Isle of White
• 168 km of coastline
• Fetch of 4000km from the Atlantic
• In 2016, 2.38 million visitors spent 300 million
pounds.
• Shoreline management plan at Bonchurch is hold the
line. Reason is to protect properties, Victorian
landscape and enlisted buildings
• Do nothing on the southwest coast. Leads to
landslides, slumping and cliff recession.
• Brook and Chale (villages), farms, houses, holiday
spots, dinosaur farm and military road at risk because
of doing nothing.
• Scenery and landscape preserved in the southwest,
loss of access for tourists, decrease in economic
benefits
• Managed realignment at St Helen’s Duver and
Bembridge harbour
• Sand and shingle spit at entrance to Bembridge
• Sea wall and groynes that will fail in these places in
the next 50 to 100 years, leaving the land exposed,
causing natural realignment.
• Following this natural realignment, they are at risk of
flooding.
• 38 properties might be damaged by 2060, and 41 by
2010.
What are the values of coral reefs
Seafood: in LEDCs coral reefs contribute about ¼ of the total fish catch, providing food for up to a billion people in Asia alone. If properly managed, reefs can yield on average, 15 tonnes of fish and other seafood per km squared/year.
New medicines: coral reefs offer particular hope because of the array of chemicals produced by many of these organisms for self-protection. Corals are already being used for bone grafts, and chemicals found within several species appear useful for treating viruses, leukaemia, skin cancer and other tumours.
Other products: reef ecosystems yield a host of other economic goods, ranging from corals and shells made into jewellery and tourism curious to live fish and corals used in aquariums, and sand and limestone used by the construction industry.
Recreational Value: The tourism industry is one of the fastest growing sectors of the global economy. Coral reefs are a major draw for snorkelers, scuba drivers and recreational fishers.
Coastal protection: Coral reefs buffer adjacent shorelines through wave action and the impact of storms. The benefits of this protection are widespread and range from maintenance of highly productive mangrove fisheries and wetlands to supporting local economies that are built around ports and harbours, which in the tropics is often sheltered by nearby reefs.
What are the human impacts upon coral
- Sedimentation (covers coral, prevents photosynthesis by zooxanthellae).
- Over-fishing
- Careless recreation
- Pollution
- Climate change
- Untreated waste water rise in agriculture and hotel development; Algal blooms due to nutrients, therefore blocks sunlight. Also uses up carbon dioxide, therefore eutrophication.
• Overfishing. (Parrot) fish eats algae, therefore, prevents covering of algae over coral. Overfishing, less algae eaten, more algae grows and covers coral, so more coral killed, due to lack of nutrients and light for photosynthesis.
Benbecula, Scotland (climate change)
The island is also regularly affected by severe gales so an increase in the frequency of ‘extreme’
weather events could also be significant.
It is possible that, with climate change, storms such as the 2005 floodings will become more frequent.
Could also have a knock-on effect on the island’s connectivity as it could affect planes and ferries – with an impact on both individual mobility and the ability of local distributors to import key goods such as food.
Why has Iran had to use an ICZM approach to coastal management
The versatility of natural sources in coastal areas has made private and governmental users and investors to participate in this section to gain the utmost profits.
The necessity of preparation and implementation of management plans for perpetual utilization of existent sources in coastal areas has become inevitable.
Iran, possessing some 6000 km of coastline in north and south, owns abundant economic capacities in coastal zones and regarding the versatility of nature and coast operators and management of coastal activities and operations, necessity of attention to Integrated Coastal Zone Management becomes more significant.
Explain the Swanage Bay area (headland and bay) (Dorset)
Discordant coastline
The area around Swanage is made up of bands of hard and soft rock.
The soft rock is made of clay and sands, and the hard rock is chalk and limestone.
The bands of soft rock erode more quickly than those of the more resistant hard rock leaving a section of land jutting out into the sea, called a headland.
The areas where the soft rock has eroded away, next to the headland, are called bays.
This process created Swanage Bay
Explain Lulworth cove (Dorset)
Concordant coastline
The alternating bands of hard and soft rock run parallel to the coast. Lulworth Cove is situated on the south coast of England, on a concordant coastline.
The entrance to the cove is narrow where the waves have cut through weaknesses in the resistant limestone. Then the cove widens where the softer clays have been more easily eroded. At the back of the cove is a band of more resistant chalk, so erosion is slower here.
Explain Old Harrys Rocks (Dorset)
Old Harry Rocks
Old Harry Rocks are located on the headland between Swanage and Studland Bay. The headland is made out of chalk, a hard rock. The headland juts out into the sea, so it is more vulnerable to high-energy waves. This caused the formation of Old Harry, a stack. Over time Old Harry will collapse to form a stump.
Explain Chesil Beach
Chesil Beach is an example of a bar. Sediment has been deposited over time to form a spit.
The spit has continued to join to the Isle of Portland. Behind the spit there is The Fleet, a lagoon.
South Devon Railway issues
- Repairing the damaged section of the South Devon Main line
railway in 2015 cost 35 million – Estimates of the cost of to
businesses in the South West were put between 60 million
– 1.2 billion - Exeter in particularly
- Government funding of £80 million to raise the sea wall south of Dawlish station by 2.5 metres (8.2 ft) was approved
in February 2019.
How many properties are vulnerable to coastal erosion
Approximately 700 properties in England are vulnerable to coastal erosion over the next
20 years and a further 2,000 may become vulnerable over the next 50 years.
2012-2013 government coastal management schemes impact
A recent project to identify the additional benefits of flood and coastal erosion risk management
schemes suggested that schemes completed during 2012-13 provided improved protection to
around 76,000 hectares of agricultural land.
What are the main coastal approaches suggested at Holderness
Flamborough: do nothing
Hornsea: Hold the line
Mappleton: Hold the line
Easington gas: Hold the line
Evaluation of hard engineering measures at Holderness
However the sea defences have a downside; they are unsightly, can be inefficient and in the long term can be
found to encourage local erosion and erosion in other places. Furthermore, sea walls make
access to the beach more difficult and can discourage tourism.
In the past, ad hoc also private sea defences have been put in place to protect assets,
particularly at Ulrome and Skipsea. While these provide a short-term protection to the
properties directly protected, their general nature and design is of concern. Private defences
are often not of the same engineering standard of those publicly funded, and pose health
and safety problems because of this –posing a danger to beach users.
Long term control of erosion would require permanent protection of the cliff and foreshore
clays. Simply defending the cliff toe through construction of a seawall or other such defence
would still allow the foreshore to erode, ultimately undermining the structure.
Maintaining a beach through effective sand control is therefore the aim when defending a frontage, the beach
itself also provides a valuable amenity asset. Once established a beach can be contained through
construction of a groyne field, the physical barrier that these structures provide prevents sand
moving along and past the frontage.
Storms can still draw sand directly seaward so beach sand is still lost and foreshore erosion does occur but at a much reduced rate.
Threats at Easington gas station
The Easington Gas terminal, which receives gas from
the North Sea gas fields, is now within 25m of the
cliff edge, with no beach to protect it.
Plans are currently being drawn up for defence works for this installation and possibly for the village of Easington
itself. A rock revetment at the base of the cliff
incorporating the full length of the site has been
suggested.
Population of the Holderness area
312,000
Major functions of the Holderness coastline
Tourism and recreation: Withernsea, Hornsea and Bridlington are the main
resorts. Beach recreation is of great importance for this area. Fishing and
caravanning are the other main tourist features at the Holderness coast.
! Urbanisation (safety of people and investments): There are four main towns -
Beverley, Bridlington, Driffield and Goole, the biggest of which is the traditional
coastal town of Bridlington, which has a population of 32,000. Other towns along
the coast are smaller, Hornsea 8.000 (count 1991) and Withernsea 6.500 (count
1991). Concluding, the main towns population and investments at the Holderness
coast are relatively small.
! Fisheries and aquaculture: The coastal waters encompassed within the East
Riding coastal zone and the associated North Sea region support a high level of
commercial and recreational fishing activity and Fishing and fishing-related
industries continue to play an important role in the life of many communities in the
East Riding coastal zone.
! Agriculture and forestry: The coastal area has a rural nature and a lot of high
quality agricultural land (because of the deposits of glacial till), mainly used for
large scale arable cultivation and intensive livestock farming.
! Industry, transport and energy: Easington houses the Easington and Dimlington
Gas Terminals which account for approximately 25% of Britian’s gas supply.
! Nature and conservation: Dunes and wetlands at Spurn Peninsula, the Lagoons
at Easington and the freshwater mere at Hornsea are very important natural sites.
Some have been designated as SSSI areas.
How much of the Holderness coast is underdeveloped
90%
Flamborough Head
On the most northerly point of the Holderness
Coast lie the distinctly layered white chalk cliffs
(topped by a layer of glacial till) of Flamborough.
The cliffs are dotted with examples of erosion
features such as caves, arches, stacks and
stumps resulting from the presence of relatively
more resistant limestone.
Hornsea
Hornsea has 2.9km stretch of shoreline fronting the town. This high-density urban development is dependent on tourism and recreation as well as a small fishing industry.
Mappleton
Situated approximately 3km south of Hornsea lies the village of Mappleton. Supporting
approximately 50 properties, the village has been subject to intense erosion at a rate of
2.0m per year, resulting in the access road being only 50m from the cliff edge at its closest
point.
Conflicts at Hornsea
The local council promised landowners facing the loss of their land and property that they would build a stone
groin at the base of the cliffs to trap sediments and reduce the power of the waves. The
inhabitants, however, were infuriated by the decision of the council not to take this action
until the cliff edge is 30m from their front door. The main concern of the council had been to
protect the British Petroleum oil and gas terminal further towards the south at Easington.
ICZM at Holderness
in 2000, East Riding of Yorkshire Council, and other interested parties agreed to
develop an Integrated Coastal Zone Management Plan for the East Riding coastal zone, the
fastest eroding in Europe. This is a plan that balances all the issues that are important on
the coast, including the environment, tourism, fisheries, agriculture and rural isolation.
Evaluate success of Holderness coastal defences
The effectiveness of the measures taken at the Holderness coast are varying but in general
the hard measures are successful in stopping or at least slowing down the erosion locally.
However, due to the use of hard measures, downstream of the measures the erosion has
increased. In between the towns with a fixed coastline, bays seem to be developing due to
this erosion.
The sea defences seem to be creating artificial headlands because erosion on
both sides continues.
As time progresses this could mean that the headlands (towns)
become more and more exposed to the force of the waves, while the coast in between the
headlands will erode more and more until a stable bay is formed.
Give an example of a Sediment cell
Flamborough head, holderness
Explain the cliff erosion at Flamborough head, Holderness
The most visible of the erosion zones, the cliff face undergoes erosion whenever the tide is high enough to allow wave action to strike its base.
Wave impact and abrasion forces are then capable of removing material so steepening the cliff face to a point where it collapses spilling material onto the beach, this clay is then rapidly removed by subsequent tides.
If beach levels are particularly low then a higher number of tides will reach the cliffs and more erosion will occur.
This erosion state will usually continue until beach levels recover, which can be anything from months to several years.
A period of relative calm will then follow until the cycle repeats again which may be in years or even decades time.
