- Created by: Henry Williams
- Created on: 28-03-13 09:18
Coastal Erosion - Walton on the Naze, Essex
- Most of the area of Walton on the Naze is built on a spit, meaning that along with there being a beach and large marshlands, it is also extremely prone to the North Sea waves.
- There is little natural defence from the destructive waves of the North Sea so they have a lot of energy when they hit the coast.
- Most of the cliffs are also made up of impermeable London Clay, which turns soft and runny when attacked by water, beneath a heavy permeable layer of Red Crag, meaning that landslides and mass movement are common.
- Most of the coasts cliff faces are also very steep so are easily attacked and undercut by waves.
- Between 1996 and 2008, the coast retreated by around 20m.
Cliff Collapse - Holbeck Hall Hotel, Scarborough
- Rotational landslide between 3rd and 5th June 1993
- 1 million tonnes of glacial till cut back the 60m high cliff by 70m
- It flowed out to the beach in a semicircular shape 200m wide and 135m out to the beach
- First signs shown six weeks before landslide in cracks in surfaces, which were filled in, but cracked again and paths were closed by the council
- 55m of the hotels garden was lost overnight
- The cliff is made up of Glacial Till (sandy, silty clay) on top of Middle Jurassic Scalby Formation.
- 140mm of rain two months before
- Drainage issues
- Water pressure build up
Impacts of Coastal Flooding - East Anglia, UK
- Social and Political – The government would have to repair and replace many transport links in order to help local residents but also to ensure good trade routes with Europe.
- Environmental – Floods would force people out of their homes, while the area is also heavily reliant on agriculture, which would be damaged heavily as habitats would be destroyed and soil would be eroded far quicker, which will force some species out of the area, even leading to the extinction of some.
- Economic – This reliance on agriculture would also damage the economy, as would the effect of tourism at sea side resorts, while airports and ports would also have to be moved or rebuilt.
Impacts of Coastal Flooding - Bangladesh
- Environmental – Low quality land and large marshes, which have been built on for housing or crops, would be destroyed, perhaps beyond repair, and floods would become even more frequent.
- Economic – Raw materials and crops, which make up the majority of the countries income, may be flooded more frequently and would therefore be destroyed, decreasing national income, while housing prices would also increase due to higher demand and lower supply due to loss of land at the coast.
- Social and Political – Food, clothing and medicine shortages would become more frequent, which would have to be managed by the government, alongside rising homelessness, frequent floods and trying to keep the economy afloat with destroyed crops.
Coastal Management - Wallasea Island, Essex
· At Wallasea Island, managed retreat (a.k.a. managed realignment) was employed as a form of coastal management.
· Old forms of coastal protection, such as a sea wall, had fallen beyond repair and the council decided to allow water from the river Crouch to beat the flood defences after building a new embankment further back.
· This led to the formation of mudflats and salt marshes behind the old sea wall, which now act as natural sea defences by absorbing the wave’s energy before it hits the coast.
· This provides habitats for animals and is environmentally friendly, with little maintenance needed so is cheap in the long term.
· However, it cost £7.5 million initially due to compensation paid to landowners whose land was lost to the river, and the mud can be dangerous to tourists.
Coastal Habitat – Keyhaven Marshes, Hampshire
· Keyhaven Marshes are a collection of salt marshes, grasslands, scrubs and reed beds located just behind Hurst Castle Spit, near Southampton. · It is home to the following rare species: Cordgrass (grass that grows on mudflats), Ringed plover (bird), Sea lavender (plant), Common blue butterfly (found on marshes), O ystercatcher (bird found in marshes), Wold spider (lives in cordgrass). · However they are under threat as: Sea level rise means they are retreating by 6m per year. Storms push over shingle ridges, leaving the area prone to huge waves from the sea. Tourists and visitors are polluting the area with cars and boats and trample areas. There is a low sea wall, meaning it is often flooded.
Flooding in a Richer Country - Mississippi, USA
The Mississippi, 6,000km in length, has a drainage basin which covers around two thirds of America and flooded heavily in 1993 for 144 days between 1st April and 30th September, worst affecting the city of St Louis.
- Cool, dry air from Canada in the north-west met worm, moist air from the Gulf of Mexico coming from the south-east, causing huge storms, meaning that 160mm of rain, 150% the monthly average, fell in 2 days in Iowa.
- The ground was already saturated with spring rainfall and 80% of wetlands had been drained since 1940 due to population growth.
- Winter snow started rapidly melting due to increasing temperatures.
- Surface run-off was hugely increased due to the number of buildings and urban areas in the drainage basin.
Flooding in a Richer Country - Mississippi, USA (E
- 60,000 houses were damaged, totalling to $10 billion of property damage, but only 10% had insurance, leading to FEMA declaring it a disaster.
- 4,000 hectares of crops were destroyed, meaning that corn production dropped by 10% for 1993.
- Energy resources ran out in many areas, and one area was without clean water for 19 days.
- Sewers overflowed and transport links became inaccessible.
- Levees were built up far higher than before, while some areas had artificial overflow channels built. Other areas had dams and reservoirs built, often involving straightening the river, as occurred at 1750km of it to get rid of meanders. Concrete was also laid on the base and wind dykes installed to keep the fastest flowing water in the centre of the river.
Flooding in a Poorer Country – Bangladesh
- Bangladesh often experiences floods from the Ganges River, but in 2004 it was even larger than normal due to the intense rainfall during the monsoon period in July and August 2004.
- Most of Bangladesh forms part of the floodplain or a delta for the rivers Ganges and Brahmaputra, while another 70% of land is extremely flat and less than 1m above sea level.
- Monsoon weather brings around 2000mm of rainfall per year.
- Deforestation of 50% of forests in Nepal.
- Ice melt from the Himalayas in Nepal, just north of Bangladesh.
Flooding in a Poorer Country – Bangladesh
- 70% of the country was underwater at one point.
- Crops were destroyed, meaning that aid had to make up for food shortages for over a year.
- Of the 35 million people affected, 760 died while 8.5 million more were made homeless and another 1 million children died due to waterborne diseases.
- $2-3 billion was spent on rebuilding roads and industry.
- Strategies for managing future floods:
- Emergency aid was improved to provide shelter, food and medicine, ensuring it was fairly distributed to all.
- The World Bank made an Action Plan for Flood Control, involving 3500km of coastal and river embankments, 7 dams and 15 floodwater storage basins.
Dam/Reservoir in the UK - Kielder Water, Northumbe
- In the 1960’s water stress levels were very high on the north-west and so Northumberland Water asked a group of specialists and engineers to carefully select a location to build a dam and reservoir, which was built on the selected Kielder area in the 1980’s.
- It was suitable for a dam as it had a large river basin with steep sides, while rainfall was also high; around 1370mm per year, and land was cheap as it was mostly low quality farmland.
- It is the UK’s largest reservoir at around 10km2.
- Despite the huge initial costs of almost £350 million, it is sustainable due to the wildlife centres on sight to look after the environment, while it also attracts tourists and visitors to the area in hotels and accommodation at the location.