Coastal environment: The Holderness Coast

Where is it?
1. The Holderness coastline is 61km long- it stretches from Flamborough Head to Spurn Head
2. Most of the cliffs are made of till (boulder clay) and the coast is exposed to powerful destructive waves from the North Sea during storms
What are the factors affecting the coastal system? Why is it eroding so rapidly?
1. Erosion- the soft boulder clay is easily eroded by wave act. In some places, e.g. Great Cowden, the rate of erosion has been over 10m/year
2. Mass movement- the boulder clay is also prone to slumping when its wet. Water makes the clay heavier and acts as a lubricant between particles, which makes it unstable
3. Transportation- prevailing winds from the northeast transport material southwards. These winds also create an ocean current, which transports material south by longshore drift. Rapid erosion means there is always plenty of sediment to be transported
4. Deposition- where the ocean current meets the outflow of the Humber River, the flow becomes turbulent and sediment is deposited
What are the coastal processes that have shaped the coast?
1. Headland and wave-cut platforms- to the north of the area, the boulder clay overlies chalk. The chalk is harder and less easily eroded, so it has formed a headland (Flamborough Head) and wave-cut platforms, such as those near Sewerby. Flamborough Headhas features such as stacks, caves and arches
2. Slumping cliffs- frequent slumps give the boulder clay cliffs a distinctive shape. In some locations several slumps have occurred and not yet been eroded, making the cliff tiered. For example, slumps are common around Atwick Sands
3. Beaches- the area to the south of Flamborough Head is sheltered from wind and waves, and a wide sand and pebble beach has formed near Bridlington
4. Sand dunes- around Spurn Head, material transported by the wind is deposited, forming sand dunes
5. Spit- erosion and longshore drift have created a spit with a recurved end across the mouth of the Humber Estuary- this is called Spurn Head. To the landward side of the spit, estuarine mudflats and salt marches have formed
Why does the coastline need to be managed?
1. The Holderness coastline has retreated by around 4km over the past 2000 years. Around 30 villages have been lost
2. Ongoing erosion could cause numerous social, economic and environmental problems such as:
  1. Loss of settlements and livelihoods- e.g. the village of Skips is at risk and 80 000m squared of good quality farmland is lost each year on the Holderness Coast
  2. Loss of infrastructure- the gas terminal at Easington is only 25m from the cliff edge
  3. Loss of Sites of Special Scientific Interest (SSSIs)- e.g. the Lagoons near Easington provide habitats for birds
What management strategies have been put in place?
1. A total of 11.4km of the 61km coastline is currently protected by hard engineering
2. Bridlington is protected by a 4.7km long sea wall as well as timber groynes
3. There's a concrete sea wall, timber groynes and riprap at Hornsea that protect the village
4. Two rock groynes and a 500m long revetment were built at Mappleton in 1991. They cost £2 million and were built to protect the village and the B1242 coastal road
5. A landowner in Skipsea has used gabions to help protect his caravan park
6. There are groynes and a sea wall at Withernsea. Some riprap was also placed in front of the all after it was damaged in severe storms in 1992
7. Easington Gas terminal is protected by a revetment
8. The eastern side of Spurn Head is protected by groynes and riprap
Why are these not sustainable?
1. The groynes trap sediment, increasing the width of the beaches. This protects the local area but increases erosion of the cliffs down-drift (as the material eroded from the beaches there isn't replenished). E.g.the Mappleton scheme has caused increased erosion of the cliffs south of Mappleton. Cowden Farm, just south of Mappleton, is now at risk of falling into the sea
2. The sediment produced from the erosion of the Holderness coastline is normally washed into the Humber Estuary(where it helps to form tidal mudflats) and down the Lincolnshire coast. Reduction in this sediment increases the risk of flooding along the Humber Estuary, and increases erosion along the Lincolnshire coast
3. All these problems make the existing schemes unsustainable
4. The protection of local areas is leading to the formation of bays between those areas. As bays develop the wave pressure on headlands will increase and eventually the coast of maintaining the sea defences may become to high
What are the future challenges?
1. The SMP for Holderness for the next 50 years recommends 'holding the line' at some settlements (e.g at Bridlington, Withernsea, Hornsea, Mappleton and Easington Gas Terminal) and 'doing nothing' along less-populated stretches. However, this is unpopular with owners of land or property along the stretches where nothing is being done
2. Easington Gas Terminal is currently protected by rock revetments, and the SMP recommends that these defences are maintained for as long as the gas terminal is operating. However, the defences only span about 1km in front of the gas terminal, meaning that the village of Easington (with a population of about 700 people) isn't protected. The defences may also increase erosion at legally-protected Sites of Special Scientific Interest (SSSIs) to the south
3. Managed realignment has been suggested e.g. relocating caravan parks further inland. This would be a more sustainable scheme as it would allow the coast to erode as normal without endangering businesses.However, there are issues surrounding how much compensation businesses will get for relocating. Also relocation isn't always possible
4. In 1995, Holderness Borough Council decided to stop trying to protect Spurn Head from erosion and overfishing- do nothing became the new strategy. This saves money and allows the spit to function naturally, but over washing may damage marsh environments behind the spit. A coastguard station on the spit may also be at risk

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Coastal environment: The Holderness Coast

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	Criado por Lily Duffy aproximadamente 7 anos atrás