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Coastal Systems Case Studies - Coggle Diagram
Coastal Systems Case Studies
Holderness
Subcell in Sediment Cell 2 comprising 3 coastal units:
Flamborough Head (exhibits many typical landforms associated with coastal erosion).
Bridlington Bay to Spurn Head (an extensive zone of erosion and sediment transfer characterised by rapid cliff retreat)
Spurn Head (spit formed at the Humber Estuary)
Main input is
erosion of the weak and unconsolidated till cliffs
.
Some of the finer sediment is the output, slightly coarser material is moved southwards as a transfer of longshore drift.
Flamborough Head:
Jutting into the North Sea.
Vertical cracks run throguh the chalk, in some places whole sections have been displaced (faults).
These are readily exploited by the processes of weathering and erosion to form narrow clefts in the coastline.
The sea is actively eroding and undercutting the base of the cliffs leading to frequent rockfalls.
Wave refraction forces waves to curve, and have low energy in the bay, resulting in a deposited beach. The more exposed headlands bear the force of incoming waves.
Chalk in compariosn with clay like the rest.
Bridlington Bay to Spurn Head:
Retreated up to 5km since Roman times.
1m per year rate of erosion
Although a human threat. It generates a a large amount of sediment for the sediment cell.
much of the finer sediment is an output offshore, but coarse sediment is transferred south (reducing erosion, negative feedback)
Spurn Head is nourished by this deposition which protects towns such as King’s Lynn.
Massive planning conundrum.
Spurn Head
Protect Grimsby, and provides shelter for mudflats.
losing biodiversity
Narrowed by approx 20m between 2003-8.
Large breach in 1996
Following the takeover by military forts, the royal engineers took the task of maintaining the coastal defences.
It was then taken over in the 1960s by the Yorkshire Naturalists’ Trust , but a lack of affording meant some defences fell into disrepair.
In 2013, the largest tidal surge in 60 years hit Spurn Point the defences could not cope where buildings were destroyed and the access tot he road swept away.
Factors affecting the coastal system
.
Chalk
(resistant rock) forms a broad arc in the region.
As the
sea levels rose
at the end of the last glacial period , the North Sea took shape and started to erode the thick till deposits to help form the present-day cliffs made from soft boulder clay.
Wind
blowing from NE it can drive powerful waves towards the Holderness coast, longshore drift operates north to south.
A fetch of 500-800 km across the North Sea
Management systems
have helped to protect specific localities such as Mappleton and Hornsea, but have deprived areas of sediment further south, exacerbating erosion through the use of groynes.
Cliffs are made of soft boulder clay, eroding especially when saturated.
Produces sloping cliffs, surrounded by chalk eroding along fault lines, forming structures like cliffs, caves, stack, and arches.
Weather systems in the North Sea are often intense, low pressure raises the sea level predicting higher tides than normal.
Deep sea floor of the North Sea, waves are not slowed down by friction.
Background
In the north east of England
The fastest eroding coastline in Europe, retreating at 2m per year.
Mappleton consists of around 50 properties, as well as important infrastructure near the coastline such as the B1242 road.
1991 scheme at £2.1 million supported by EU finding.
Since Roman times, the Holderness Coast has retreated 4km losing around 30 villages.
Management
1991
2 rock groynes to help build a larger beach
Rock armour placed at the base of cliffs, helping absorb wave energy
Beach nourishment.
Results
The management scheme was successful
Mappleton, B1242, and Mappleton cliffs are no longer at great risk from erosion.
Interfered with longshore drift, increasing erosion South of Mappleton.
Great Coswen (3km south) have seen rapid erosion rates which threatens farms and business establishments.
In some areas, the erosion rate is now 10m annually.
Near the gas terminal of Easington, rock armour had to be implemented for £6.6 million.
Supplies 25% of UK’s gas.
Terminal groynes syndrome
Shoreline Management Plan
2010
Plan for managing flood and erosion risk for a particiular stretch of coastline, to develop a sustainable management approach taking in most amount of key issues.
Operate on short, medium, and long term temporal measures.
Highly varied coastline with different land uses and environment.
Floodplains include some of the most productive agricultural land in the UK.
Combines HTL, ATL, MR and NAI
No Active Intervention
Flamborough Head
Hold the Line
Bridlington Bay
Hornsea
Mappleton
Easington (gas terminal only)
Managed Realignment
Spurn Point
Odisha Coast
Background
Eastern coast of India, bordering the Bay of Bengal
It is 480 km, where most of the population of the state live, with the 11th largest population in India.
Mainly depositional landforms so is a sediment source for the Bay of Bengal.
The six deltas provide important transfers of sediment.
Chilika Lake is a salty lagoon that is home to 150 species of birds.
Enhances biodiversity as well as a large tourist attraction.
Temporary store in the water cycle during monsoon cycle occupies a larger, less saline area.
The largest employment sector is agriculture, specifically coastal fishing.
Opportunities for human occupation and development
Wide variety of coastal flora and fauna.
Large stocks of fish
Offshore, wind, wave and tidal power
Offshore oils dn natural gas
Cultural and archaeological sites dotted along the coast
-Valuable minerals such as clay and limestone.
Risks for human occupation and development
Volume of population living along coastline causes concern for the Indian government.
Most of the erosion is in the south where human intervention such as sea walls and rock armour are interfering with natural processes.
Most accretion in the north
Shoreline change is extremely dynamic along the mouths of rivers suggesting that the inflow pattern determines the nature of the shoreline.
Tropical Cyclones
October 2013 Cyclone Phailin
wind speeds of 200 kmh, 1 million were evacuated , 44 died.
Coastal district of Ganjam was most severely affected.
Economic losses close to US$700k.
Damage to Chilika Lake.
Odisha Cyclone 1999
Most intense cyclone recorded in the Northern Indian Ocean
Killed 15,000
Category 5 hurricane
260 kmh winds
Flooding
2022 flooding displaced 60,000 people after a period of heavy rain in August.
Erosion
Rates of erosion increased partly through natural processes but also human intervention methods to protect infrastructures.
Odisha lost 28% of its coastline between 1999-2016
A study by the Integrated Coastal Zone Management Project found around 10% of Odisha’s coastline is highly vulnerable to sea erosion.
Frequency and magnitude of erosion has increased from cyclones and flooding
Construction and embankment activities
Changing wind patterns are causing high tidal waves and inundating habitable areas.
Reduces availability of viable farmland.
Rising Sea Levels
Sea levels across the Indian coast are projected to rise from 3.5 inches to as much as 34 inches by the end of the century due to global warming.
Seasonal Variation
Accretion in summer during low energy wave conditions, and erosion in winter when high energy destructive waves remove and deposit sediment offshore
Monsoon season usually starts at the beginning of June, under infiuence until September.
Management
Joint venture of Ministry of Forest and Environment and the Indian Government , the World bank and the government of Odisha highlighting major issues:
coastal erosion and associated oceanographic processes.
vulnerability to disaster
biodiversity conversation
livelihood security
Management of the Mahanadi Delta
Important ecological Zone
Recent considerable loss of mangroves due to the development of fisheries and other economic demands.
With a 3.9km reduction in the average width of mangroves protecting the villages in Odisha.
They are a protective belt from cyclones, (those with more than 4km recorded no deaths in 1999)
This is trying to o be reversed by the NGO Wetlands International and the ICZM Project helping villagers plant and cultivate mangroves along the coastline and river banks. Sustainable and highly appropriate.
Mangroves
145km sq planted
Wind and swell waves reduced
Roots bind and build soils, and are cheap to plant.
Mangrove peat absorbs water during heavy rains and storm surge
Olive Ridley sea turtles come to nest on some of Odisha’s beaches, who are at risk from uncontrolled mechanised fishing in prohibited areas.
Parts of the mangroves have been reclaimed for cultivation, fuel wood, and timber
Delicate ecosystem is vulnerable to alteration of freshwater inflows due to construction of hydrological structures upstream.
Integrated Coastal Zone Management
A means to accept and culminate different objectives for coastal areas in such an order that multiple social, economic, cultural and environmental goals can be achieved.
Completed construction of 14 multipurpose cyclone shelters.
Established gene bank of mangrove species established, with planting incentives and training to plant mangrove nurseries.
Turtle awareness is being raised among locals and tourists
Completion of solid waste management system for the coastal town of Paradip to protect nesting habitats.
Improve the livelihoods of resource-dependent communities, training for agriculture jobs, and small-scale community based tourism
400,000 people from 235 coastal villages said to benefit from the measures.
Regulation of motor boat traffic around Chilka Lake
300+ fishing boats converted into eco-friendly vessels
All fishing is to be certified by the Marine Steweardship Council
Effectiveness of the project is argued however as16 villages as of March 2023 have already gone underwater, with 247 facing displacement due to sea level rise.