a) Why is the coastline retreating at Holderness? (consider geology, human factors, marine and sub-aerial processes)
During the Pleistocene Ice Age in Britain around 18,000 years ago deposits of glacial till were built up against cliffs to form the new modern day coastline. This is rock type is a soft boulder clay consisting 72% mud, 27% sand and 1% boulders and stones. The strong marine erosional processes such as abrasion, hydraulic action and corrosion can easily erode this soft boulder clay. This leads to the coast retreating and this problem is exacerbated by the strong prevailing winds from the North Sea. Also Flamborough head causes waves to refract around it leading to the waves being concentrated in this area causing increased amounts of erosion.
The seabed is made of glacial mud and sand therefore it is also easily eroded and at Dimlington Highland the 10 metres submarine contour is only 600 metres away from the beach. The waves from the North Sea can erode the cliffs with hardly any resistance. The beaches of Holderness are generally very narrow and unable to stop wave erosion leading to even further retreating of the coast.
Due to these factors the settlements such as Hornsea have put measures in place to protect themselves and keep their main industry from disappearing. Their main industry in the summer is that it is a holiday resort therefore it needs its beaches to exist not to be eroded away by aerial processes. They built groynes that solved the problem in their stretch of the coastline but starved other areas further down the coast of sediment to protect themselves from marine erosional processes. This problem is made worse by the fact that in Mappleton there is a layer of sand on top of the boulder clay. This is hugely problematic when it rains as the sand is permeable therefore allows water through it however when the water reaches the boulder clay underneath it cannot pass through as it is impermeable. The water sits there leading to slipping especially in areas near the coast and cliffs.
There are also sub-aerial processes that erode the coastline such as rain mentioned above. Biological factors as plants break into cracks and crevices making them bigger and therefore more susceptible to further erosion due to other processes. Storm surges occur around one every year which have waves that are around 5 metres and in Hornsea this is a problem especially. Just to illustrate how quickly the coast is retreating; over the last 2,000 years the coast has retreated over 4.3 km in Easington. That means that around 2.15 metres of coast are lost every year, which is extremely fast in geological terms and is a matter for concern as in Easington there are large gas installations.
b) What evidence is there of coastal retreat? (consider impacts on the physical environment & on people) Why does it need to be managed?
The coast at Easington 2,000 years ago was 4.3 km out to sea and is retreating at a rate of 2.15 metres per year. Also it is estimated that 30 coastal villages have disappeared since Roman Times.
Further evidence of coastal retreat is that settlements have taken measures to protect themselves from coastal erosion or at least try to minimize it. In Hornsea there are seawalls and groynes and down the coast near Spurn Head at Easington there is kilometre long rock armour at the base of the cliffs. Mappleton has a 500m long revetment as well. There has been serious damage to infrastructure as homes, farmland, roads have fallen into the Sea.
c) Which users of the Holderness coastline are in conflict over the coastal protection? (page 7 of the case study, linked above, will help)
Management of a small stretch of coast can have serious effects further down the coast. Governments have finally realised that material eroded away from the cliffs by marine processes such as hydraulic action is extremely important down the coast and eventually in the Humber. It has been predicted that by having the whole of the Holderness coastline protected there will not be enough sediment flowing into the Humber estuary leading to less material on the bed of the Humber and increase the chances of flooding. That is why certain areas of the coast are left unprotected, as they are sacrificial coastlines. This of course leaves home or land owners in this area extremely angry as they are losing money and some farmers are losing £5,000 and an acre a year. In Mappleton a revetment was installed as the villagers lobbied the council and the main road was under threat in 1990 regardless of the consequences down the shore.
Spurn Head is an area where they are lot of birds so it attracts bird watchers that in turn influence the economy of the region. If sediment were not to come down the coast and be deposited on the Spit because of Longshore drift then this land might be potentially lost. Areas with relatively low populations get defenses due to the economic importance of them. A good example of this is Easington that has a gas terminal that receives 25% of the UK gas so it needs to be protected which disgruntles other areas that have larger populations. This especially infuriated the inhabitants of Hornsea who were denied rock armour until the sea was 30m away from their doorstep to safeguard the interests of the gas terminal and BP.
d) Describe two other methods of soft engineering that are used to protect a coastline.
Building Bars-
Underwater bars located just offshore reduce wave energy.
Fencing, hedging and planting vegetation-
This helps to preserve a beach or sand dune by reducing the amount of sand that is blown inland.
e) Use the resources to write a paragraph about the Shoreline Management Plan (SMP) that has been developed for Holderness - what is a SMP? When was it drawn up? How is it being implemented? Which organisations are involved? Does it vary down the coastline? What factors are considered?
The Shoreline Management Plan (SMP) was drawn up in August 2009 and was fully finished by the end of the same year. The Holderness coast is the most rapidly eroding coastlines in Europe and is the most significant source of sediment for other coastlines further south. The Shoreline Management Plan aims to find a sustainable balance between protecting property and economic viability of the Holderness coast (such as retaining sandy beaches for tourism) with allowing some erosion to take place to provide sediment for coastlines further south such as the Humber Estuary (preventing chances of flooding) and the Lincolnshire coast. This however means there will be sacrificial coastlines and cost/benefit comes into play here as well. To protect certain areas factors affect the decision making such as high populations, industry and reliance on a sector. Organisations such as Natural England, Environment Agency, English Heritage and the National Farmers union along side many councils in the area are working on the SMP.
During the Pleistocene Ice Age in Britain around 18,000 years ago deposits of glacial till were built up against cliffs to form the new modern day coastline. This is rock type is a soft boulder clay consisting 72% mud, 27% sand and 1% boulders and stones. The strong marine erosional processes such as abrasion, hydraulic action and corrosion can easily erode this soft boulder clay. This leads to the coast retreating and this problem is exacerbated by the strong prevailing winds from the North Sea. Also Flamborough head causes waves to refract around it leading to the waves being concentrated in this area causing increased amounts of erosion.
The seabed is made of glacial mud and sand therefore it is also easily eroded and at Dimlington Highland the 10 metres submarine contour is only 600 metres away from the beach. The waves from the North Sea can erode the cliffs with hardly any resistance. The beaches of Holderness are generally very narrow and unable to stop wave erosion leading to even further retreating of the coast.
Due to these factors the settlements such as Hornsea have put measures in place to protect themselves and keep their main industry from disappearing. Their main industry in the summer is that it is a holiday resort therefore it needs its beaches to exist not to be eroded away by aerial processes. They built groynes that solved the problem in their stretch of the coastline but starved other areas further down the coast of sediment to protect themselves from marine erosional processes. This problem is made worse by the fact that in Mappleton there is a layer of sand on top of the boulder clay. This is hugely problematic when it rains as the sand is permeable therefore allows water through it however when the water reaches the boulder clay underneath it cannot pass through as it is impermeable. The water sits there leading to slipping especially in areas near the coast and cliffs.
There are also sub-aerial processes that erode the coastline such as rain mentioned above. Biological factors as plants break into cracks and crevices making them bigger and therefore more susceptible to further erosion due to other processes. Storm surges occur around one every year which have waves that are around 5 metres and in Hornsea this is a problem especially. Just to illustrate how quickly the coast is retreating; over the last 2,000 years the coast has retreated over 4.3 km in Easington. That means that around 2.15 metres of coast are lost every year, which is extremely fast in geological terms and is a matter for concern as in Easington there are large gas installations.
b) What evidence is there of coastal retreat? (consider impacts on the physical environment & on people) Why does it need to be managed?
The coast at Easington 2,000 years ago was 4.3 km out to sea and is retreating at a rate of 2.15 metres per year. Also it is estimated that 30 coastal villages have disappeared since Roman Times.
Further evidence of coastal retreat is that settlements have taken measures to protect themselves from coastal erosion or at least try to minimize it. In Hornsea there are seawalls and groynes and down the coast near Spurn Head at Easington there is kilometre long rock armour at the base of the cliffs. Mappleton has a 500m long revetment as well. There has been serious damage to infrastructure as homes, farmland, roads have fallen into the Sea.
c) Which users of the Holderness coastline are in conflict over the coastal protection? (page 7 of the case study, linked above, will help)
Management of a small stretch of coast can have serious effects further down the coast. Governments have finally realised that material eroded away from the cliffs by marine processes such as hydraulic action is extremely important down the coast and eventually in the Humber. It has been predicted that by having the whole of the Holderness coastline protected there will not be enough sediment flowing into the Humber estuary leading to less material on the bed of the Humber and increase the chances of flooding. That is why certain areas of the coast are left unprotected, as they are sacrificial coastlines. This of course leaves home or land owners in this area extremely angry as they are losing money and some farmers are losing £5,000 and an acre a year. In Mappleton a revetment was installed as the villagers lobbied the council and the main road was under threat in 1990 regardless of the consequences down the shore.
Spurn Head is an area where they are lot of birds so it attracts bird watchers that in turn influence the economy of the region. If sediment were not to come down the coast and be deposited on the Spit because of Longshore drift then this land might be potentially lost. Areas with relatively low populations get defenses due to the economic importance of them. A good example of this is Easington that has a gas terminal that receives 25% of the UK gas so it needs to be protected which disgruntles other areas that have larger populations. This especially infuriated the inhabitants of Hornsea who were denied rock armour until the sea was 30m away from their doorstep to safeguard the interests of the gas terminal and BP.
d) Describe two other methods of soft engineering that are used to protect a coastline.
Building Bars-
Underwater bars located just offshore reduce wave energy.
Fencing, hedging and planting vegetation-
This helps to preserve a beach or sand dune by reducing the amount of sand that is blown inland.
e) Use the resources to write a paragraph about the Shoreline Management Plan (SMP) that has been developed for Holderness - what is a SMP? When was it drawn up? How is it being implemented? Which organisations are involved? Does it vary down the coastline? What factors are considered?
The Shoreline Management Plan (SMP) was drawn up in August 2009 and was fully finished by the end of the same year. The Holderness coast is the most rapidly eroding coastlines in Europe and is the most significant source of sediment for other coastlines further south. The Shoreline Management Plan aims to find a sustainable balance between protecting property and economic viability of the Holderness coast (such as retaining sandy beaches for tourism) with allowing some erosion to take place to provide sediment for coastlines further south such as the Humber Estuary (preventing chances of flooding) and the Lincolnshire coast. This however means there will be sacrificial coastlines and cost/benefit comes into play here as well. To protect certain areas factors affect the decision making such as high populations, industry and reliance on a sector. Organisations such as Natural England, Environment Agency, English Heritage and the National Farmers union along side many councils in the area are working on the SMP.
No comments:
Post a Comment