- Created by: HannahPink1
- Created on: 04-01-18 11:46
Aswan Dam: The Nile Delta
- Dam built, river discharge gell from 35 billion m3 to 10 billion m3
- Sediment volume fell from 130 million tonnes to 15 million tonnes
- Erosion rates in Rosetta jumped from around 25m a year to over 200m as delta starved of sediment
- Dynamic equilibrium disrupted
- Water withdrawals for industry, citied and farming from the reservoir behind Aswan (Lake Nasser)
- Sediment being trapped by the reservoir and dam; water in the reservoir flowed slowly allowing deposition of sediment after loosing energy
Islands at Risk: The Maldives
- Highest point only 2.3m above sea level
- Population of 340,000 over 1200 islands
- Sea level of 50cm = loss of 77% of land area
- Areas remaining emerged at risk of erosion and storm surges
- Capital, Male ringed in 3m high sea wall
- New artificial island built at the cost of US$32million, 1m higher called Hulhumale
The 1953 & 2013 North Sea Storm Surges
- Took 2500 lives
- Occurred in January
- 325 from the UK died
- Same meteorological conditions repeated themselves
These conditions are:
1. As the storm moved over Iceland it deepened
2. Winds over 140mph recorded in Scotland
3. Gale-force winds drove storm waves to nearly 6m
4. Surge corresponded with high tides in many places, making flooding worse
Impacts of the 2013 Storm Surge
1. Significant coastal flooding in Boston, Hull, Skegness and more.
2. Scotland's rail network shut down.
3. 100,000 Scottish homes lost power.
4. 2500 coastal homes and businesses in UK flooded.
4. 15 deaths.
Human and economic impacts were lower than 1953 surge because of better forecasting, warning, evacuation and flood defences.
Comparing Storm Surges in Bangladesh
1977 Bhola Cyclone
Storm surge height: 10m
Max wind speeds: 205kmph
Economic losses: US$90million
2007 Cyclone Sidr
Storm surge height: 3m
Max wind speeds: 260kmph
Economic losses: US$1.7bill
Compensation for East Riding, Yorkshire
- There is no nationwide scheme to compensate those who are losing their homes to erosion
- There is limited help from the Department for Environment, Food and Rural Affairs (DEFRA)
- DEFRA provided East Riding with £1.2million to assist 43 homeowners with relocation and demolition
East Riding Council offers help through its Coastal Change Fund:
- covering the cost of property demolition and site restoration
- offering up to £1000 in relocation expenses
- offering up to £200 in hardship expenses
The council expects up to 100 homes to be lost in the next decade.
Hard Engineering Mega Projects: Deltawerken
- Started after the 1953 storm surge in the Netherlands where the most deaths were suffered
- Wanted to reduce flooding
- Shorten length of coast exposed to sea by 700km
- Control the flow of rivers to reduce flood risk
- Maintain safe access to North Sea for shipping from Dutch ports
- Series of dams and sluice gates constructed between the islands that make up Eastern Schelt
- Gates can be closed during storm surges
- Embankments built to act as flood walls around the island and along the coast
- Plan cost US$5 billion
- Still, doesn't eradicate flood risk, especially with rising sea levels
Sustainable Management: The Maldives
- Money spent protecting the capital city Male and creating new artificial islands will leave isolated islands unprotected and ignored
- Sustainable management of traditional resources is overlooked in favour of protecting urban tourism development from coastal threats
The Maldives had a potential for conflict.
However, some actions are being taken to protect the smaller islands:
- Mangroves for the Future is working on education and the importance of maintaining coastal mangrove swamps as natural defences
- Global Environment Facility has provided small grants to islanders to help them develop sustainable and organic farming as an alternative to unsustainable fishing practices
The Japanese government has funded mangrove nurseries to the Maldives can replace damaged areas.
Hornsea and Mappleton
Impacts of policy options on the Holderness Coast.
In Hornsea, they want to Hold the Line:
- Population of 8500 and an economic centre for the region
- Important historic sites
- Inland hosts an SSSI (Site of Specific Scientific Interest)
Mappleton was protected in the 1990s:
- 2 rock groynes
The area is unlikely to be defended in the future, leading to:
- Up to 400m could be lost by 2105
- The main road B1242 could be destroyed
- 200ha of farmland and 32 properties lost to erosion
The Blackwater Estuary
An area of tidal salt marsh and low-lying farmland, prone to flooding and coastal erosion. Coastal defences defending it in the past are no longer sustainable due to coastal squeeze:
- As sea levels rise, salt marshes respond by moving further inland
- Sea defences will prevent this, causing the salt marsh to disappear
- This would remove natural protections exposing sea defences to direct wave attack
The solution was radical. Essex Wildlife Trust purchased Abbotts Hall Farm on the Blackwater Estuary and a 4000-hectare managed realignment scheme was implemented by creating 5 breaches in the sea wall in 2002.
The scheme had a number of benefits:
- Abbotts Hall Farm owners received market price for a threatened farm
- High costs of hold-the-line avoided
- Water quality in the estuary improved due to expansion of reed beds
- New paths and waterways created for leisure activities
- Additional income streams from ecotourism and wildlife watching created
- Important bird habitats and fish nurseries enhanced
An Example of a Sediment Cell:
See Holderness Coast case study, including compensation for east riding, mappleton and hornsea and the holderness coast cards.
The Holderness Coast: A Rapidly Eroding Environmen
Some areas being eroded up to 4m a year, houses regularly collapse into the sea, 100s set to collapse in coming decades and house prices reduced to £1. In some areas, 51m have been lost in just 40 years.
Flamborough Head (wave cut platform cliff), Mappleton, Alsborough, Withernsea, Kilnsea and Spurn Head (6km recurved spit) make up the Holderness Coast.
- Weather - winter storms producing surges and increasing weathering.
- Waves - large fetch and destructive waves.
- Geology - chalk and boulder clay environment, both easily eroded.
See Hornsea and Mappleton case studies. Other interesting notes: Withersea has decided on sea walls protected by rip-rap and the creation of promenade whilst just south at Spurn Head they have decided on managed retreat since 1995.