Case Studies: The Sundarbans and Holderness

What is the local case study?

Holderness

What is the contrasting coast case study, far away?

The Sundarbans

Where is the Sundarbans?

located SW of Bangladesh

What is the Sundarbans?

a low-lying area

has the largest and continuous mangrove forest in the world, covering 10,000 square km

provides sustainable livelihoods(wood-cutters, leaves,grass gatherers etc.) management and protection(home to endangered Royal Bengal Tiger) for millions of people

area is susceptible to cyclones, tidal surges

What is the Holderness Coast?

• It is a well-known stretch of coastline in Eastern England 

• Forms a subcell in Sediment Cell 2; with the main input being erosion of the weak and unconsolidated till cliffs. Some of the finer sediment is washed offshore (and output from the system), while the slightly coarser material is moved southwards as a transfer involving longshore drift. Some sediment is deposited to form Spurn Head, while a significant amount continues south towards the West and East Anglia. 

• Compromised of 3 distinct coastal units: Flamborough Head in the north; Bridlington Bay; Spurn Head. 

What physical factors affect the rapid rate of erosion in the Holderness coast?

Geology

Wind

How does the physical factor of geology affect the rapid rate of erosion at the Holderness coast?

at Flamborough Head, there is lots of chalk, which is a resistant rock. As 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. However, there are also many clay cliffs present, especially in the south, which become easily saturated and eroded. Due to the differential rate of erosion, it has given the coastline a distinctive shape. 

How does the physical factor of wind affect the rapid rate of erosion at the Holderness coast?

due to the saturated clay cliffs, they suffer increased runoff to slumping and other mass movements. Moreover, wind is blowing NE, which is the direction of the greatest fetch, so very powerful waves attack the Holderness Coast. Sometimes, when areas of very low pressure move down the North Sea, they produce funnelling water and storm surges, events of high-magnitude which lead to significant erosion. From these powerful waves, longshore drift operates from north to south. 

What human factors affect the rapid rate of erosion of the Holderness coast?

Hard engineering structures

people on the coast

global warming

 How does the human factor of hard engineering structures affect the rapid rate of erosion at the Holderness coast?

• due to the obvious erosion, structures like seawalls and groynes have helped protect specific locations like Hornsea and Mappleton. However, they have deprived areas further south of sediment, and the lack of beach renders their cliffs much more vulnerable to undercutting and collapse. 

How does the human factor of people on the coast affect the rapid rate of erosion at the Holderness coast?

these turn physical processes into hazards; due to increasing population levels around Hornsea, the risk of erosion has significantly increased, to the point where a gas terminal was threatened.

How does the human factor of global warming affect the rapid rate of erosion at the Holderness coast?

• increases rise in sea level and severe storms, meaning places like Spurn Head are at great risk of coastal flooding and erosion 

Sundarbans: coastal enviroment - coastral processes ; 3 things

primary natural process - tidal action

• shapes coastal landscapes, as there is a well-developed network of interconnecting river channels

• location of channels is quite static as the silts and clays it runs thru is very resistant to erosion

non-cohesive sediments are washed out of delta and deposited on banks, where strong SW monsoon winds blow them into large ranges of sand dunes; protection of dunes means finer silts washed into bay are shaped with further deposits to form new islands

vegetation establishes→lets natural succession proceed→ deep mangrove forests can develop

tidal and wave action maintains coastal landscape, bringing rich sediment for diverse mangrove forests

equilibria of natural processes very delicate, increasing pressures therefore jeopardise area.

Impact of erosion at Holderness:

• The Holderness boulder clay cliffs are retreating in average at 1.8m per year 

• Due to increasing population levels around Hornsea, the risk of erosion has significantly increased, to the point where a gas terminal was threatened. (look above)

• Over the last centuries, many villages have been lost, and many are threatened currently

Characteristics of Flamborough Head:

Its formation as a headland is mainly due to being made of chalk (resistant, sedimentary rock). The layers of the chalk are clearly visible, including joints and faults, which are weaknesses in chalk and so are readily exploited by weathering processes of erosion. One major fault line has been exploited to form Selwicks Bay. 

Processes occurring at Flamborough Head:

the sea is actively eroding and undercutting the cliffs’ bases, leading to frequent rockfalls. As the cliff retreats, there is formation of wave-cut platforms and stacks. 

Management strategies: at Flamborough Head:

there is no management strategies, as there are reduced erosion and also less communities on the headland.

Economic and Environmental Opportunities in Sundarbans

• provides a wide range of goods and services

• Goods: fuel(firewood and charcoal); household items(glue+ wax etc. ); food and drink(honey,fruits, etc.)

• Services: protection from floods, shoreline erosion, cyclones ; provision for livelihoods and nutrition grounds etc.

Has coastal erosion been a problem in the Sundarbans?

NO

Natural challenges in the Sundarbans:

coastal flooding

cyclones

high levels of salinity in soil

human -eating tigers

Human - induced challenges in the Sundarbans:

over-exploitation of coastal resources from vulnerable habitats

conversion of wetlands to intensive agriculture and settlements

destructive fishing techniques

Bridlington Bay - Mappleton: characteristics

stretch has retreated up to 5km since Roman times. Here sediment is brought by longshore drift. Protects the towns/land bordering the River Humber. 

Bridlington Bay - Mappleton: Processes occuring

rates of erosion in excess of 1m annually, however sediment is transferred by longshore drift to the south, which builds up beaches and reduces erosion negative feedback system.

Bridlington Bay - Mappleton: Management strategies

In 1786 in Mappleton, the village was 3.5kms from the sea, therefore to combat this in 1991 a scheme was implemented, funded 2.1 million pounds by EU funding; this included 2 rock groynes, and a rock revetment to prevent cliff erosion. Moreover the cliffs were re-graded to reduce slumping, and the beach was re-nourished. However in 2002, the re-graded cliffs were showing signs of slumping, and cliff face behind the car park had begun to erode. 

Spurn Head: Characteristics

a spit (temporary sediment store). Most of its material is derived form Holderness coast, transferred south by longshore drift; when reaching the RIver Humber estuary, the spit forms. It is a very narrow spit.

Spurn Head: Processes occuring

spit has been breached and destroyed by major storms. And has gone through cycles of growth and decline as it formed at the end of the last glacial period.

Spurn Head: Management strategies

following a massive breach in 1849, groynes and revetments were made to stabilise the spit. When military forces were established at Spurn point, the military took the task of maintaining coastal defences, and in 1960, the Yorkshire Naturalists’ Trust took over. HOwever, the Trust had to let some sea defences fall into disrepair as they could not afford the maintenance of the spit. In 2013, whe the largest tidal surge hit Spurn Point, the defences could not cope, with access roads being swept away. 

Spurn Head’s abandonment (Management strategies): Pros and Cons

Advantages: the growing annual costs of protection were saved, and since there may be no other long term solution, many people were not against it becoming an island.

Disadvantages: the community of lifeboat men, coastguards and families may have to move elsewhere. There may be a loss of a heritage site and an important bird habitat. 

The human response to challenges in the Sundarbans - Resilience

the wealth of goods and services from SUndarbands has sllowed local pops to be resilient

mangrove forests provide a high level of resilience, providing significant protection from storm winds, floods, tsumanis etc.

density of 30 trees per 0.01 ha said to reduce tsunami’s force by 90%

soil’s fertility +ecological diversity provides many nutritious foods

forest has economic value, like fishing, timber, etc.

one ha of mangrove forest has economic value of >$12,000

The human response to challenges in the Sundarbans - Mitigation:

communities utilise a number of open access natural resources

Khas land(gov. owned protected land); wet lands and fisheries, forests

sig. investment in physical infrastructure due to threats of natural disasters(roads, telecomms, schools)

many communities have good levls of social capital, from legal framework by formal governments and NGO organisations, alongside traditional laws to manage use of region.

Possible impacts of sea level rise on coastal processes and coastal landforms:

• Sea level rise impacts the height of the tide, meaning it will reach much further areas of the cliffs, meaning formations of wave-cut platforms will be much faster. 

• Increased chance of coastal flooding

• Extremely waterlogged soils, meaning increased chance of coastal flooding.

How effective is the communities’ resilience and mitigation?

the community’s level of resilience may be decreasing due to poverty and marginalisation of coastal communities increases

this means shrinking open access resources; degradation of ecosystems, etc.

Future challenges in the Sundarbans:

increased frequency + intensity of floods

flood waters remaining for longer

rising temps contribute to increased levels in soil

increased pesticide and fertiliser use affects water quality

Future adaptations in the Sundarbans:

grassroot NGOs run education programmes to encourage farmers to go back to traditional, eco-friendly methods

NGOs provide education +training about community

organisations like US Aid train communities to become resilient to future climate shocks, like providing training on improving farming techniques.

build more multi-purpose cyclone shelters, equipped with coms equipment, also serving as primary schools/community facilities

gov. built 100 shelters in coastal Bangladesh between 2011 and 2015

ICZM Project for Sundarbans:

works in 2 pilot stretches, the Digha- Shankarpur coast and and Sagar Island(largest island in Bay of Bengal) on the Indian side of Sundarbans

protects hazard prone areas of the coastline from erosion by planting mangroves as a bio-shield

regeneration of mangroves has started on 1,000 hectares

all fishing around Digha is to be certified by the Marine Stewardship Council

Total Project Cost: $285.67 million

had salt resistant rice so if flooded, then rice not affected (no economic/social impact)

What are erosion rates at Mappleton?

excess of 1m per year

Successfulness of groynes implemented at Mappleton:

consequently led to Old Cowden being starved of sediment

over 100 years, how much have sea levels risen?

6-8 inches

Difference between ICZM’s and

ICZM: holistic, focuses on local community, more focused, big scale

SMP: small scale, more mid-scale, takes in less factors

What strategy does Holderness coast use?

An SMP

split into 7 areas

everything to do w managment there in SMP.