The Coastal Environment AQA B Geography Revision Guide

Transcription

1 The Coastal Environment AQA B Geography Revision Guide Case Study: How is the Holderness Coast an example of a multi-use area? Definition: A multi use area is a part of the coastline which offers a range of social, economic and environmental activities. Flamborough Head stunning scenery and birds attracts tourists to visit. Bridlington provides retirement homes with sea side views. Hull Every year, 13 million tonnes of imported cargo pass through the port which employs 5000 people. Fishing industry lands fish at Hull docks. Holderness Country Park provides tourists with a large fishing lake and a dog walking area. Guests can stay in either log cabins or caravans. Easington Gas Terminal provides 1000 jobs and 25% of UKs gas supply. Humber Estuary: off-shore & on-shore wind turbines use strong winds to generate renewable electricity. Case Study: Why has the Holderness Coastline developed? Human Activities Improved Transport Rising living standards Range of jobs (e.g. Easington for industry, Bridlington for tourism). Tourism (scenery and wildlife) (e.g Flamborough Head and Spurn Head) Attractive place to live (e.g. Bridlington views of the sea) Second homes/retirement (e.g. Bridlington) Economic Activities Improved Transport and Communication Available space (e.g. Hull for development of industry and housing) Large workforce (e.g. Hull which employs 5000 people in its dockland) Natural Resources (e.g. fish in Hull, gas in North Sea piped to Easington) Tourism (e.g. Hornsea, Bridlington, Various caravan and camping sites along the coastline)

2 How is development impacting the environment? Some animals and birds have choked on litter on beaches from tourists. Diesel/oil spillage from the tankers may affect marine life; noise from tankers Industrial units and factories have polluted the sea causing death of aquatic life and thus disrupting food chains. Conflicts of Interest : Different coastal users who make problems for each other. Oil refineries of S. Humber pollute water for local fishermen. Ships coming up R. Humber cause danger for tourist wind-surfers & jet skiers Wind turbines at Easington can kill migrating birds using Spurn for migration. How is development along the coast damaging the local environment? Cliff top developments have made the cliffs unstable which has increased rates of erosion. Coral reefs (e.g. St Lucia) are being damaged from tourists collecting souvenirs and anchors from fishing vessels. Footpath erosion at Flamborough Head due to high tourist numbers. Sea defences along the Holderness Coastline have stopped the movement of sediment to Spurn Head, an important habitat for numerous rare birds. Case Study: How is the Holderness Coastline protected? Protection Scheme Heritage Coast at Flamborough Head Yorkshire Wildlife Trust at Spurn and Flamborough Head Greenbelts around Bridlington and Hull Marine Conservation Sites (MCS) How does it protect the coastline? -Encourages the use of public transport which reduces cars, congestion, noise and air pollution - farmers receive extra money through grants if they farm in a way that protects the environment and wildlife biodiversity (range of species) - footpath erosion is reduced by encouraging people to stay on paths through signage -Organises seasonal beach cleans at two locations. All rubbish is separated out and recycled where possible which promotes sustainability -Helps to prevent millions of marine animals, birds, turtles and fish dying each year as a result of entanglement or eating litter floating around in the sea or beach. -Keeps beaches tidy which encourages tourists back into the area. -they have prevented new houses and industries from being built land ideal for farming land. -fewer development on cliff-faces has reduced the pressure on cliffs making them more resistant to erosion and weathering. -stopped woodlands and hedges being removed allowing for ecosystems to continue to flourish. -The MCS has helped reduced overfishing to protect fish stock numbers from further declining. In the future, it is hoped that fish populations will increase. -The MCS also prevents sand dredging of the sea bed which can damage nesting sites of many fish.

3 What are the differences between constructive and destructive waves? Swash is the movement of water up the beach Backwash in the movement of water down a beach What determines the strength of a wave? - Strength of the wind - How long the wind has been blowing - The distance between the ocean the wave has crossed (fetch) Constructive Waves Strong Swash, Weak Backwash Deposits rather than erode Low wave height (less than 1 metre) Low wave frequency Destructive Waves Weak Swash, Strong Backwash Erodes rather than deposits High wave height (more than 1 metre) High wave frequency. What are the types of erosion and weathering? Key Terms: Erosion the wearing away of rocks by the action of the sea and their removal Weathering the breaking up of rocks in situ by the action of the weather, chemicals and biology. Erosion Weathering Attrition Energy from breaking waves causes rocks and pebbles to smash into each other They eventually break down into smaller and rounder pieces Abrasion Materials, like boulders, pebbles and sand are hurled against the cliff by breaking waves. This causes undercutting and the breaking up of rocks. Hydraulic Action Water is thrown into cracks within the cliff by breaking waves. Air inside the cracks is squashed by the water and the pressure inside increases When the wave sinks back, the pressurised air expands explosively. This causes the rocks to shatter so the cracks slowly become bigger and deeper. Wetting/drying Constant wetting and drying causes rocks to expand and contract, resulting in surface cracks and weakening of the rock. Freeze thaw Weathering Water gets into cracks in rocks and expands as it freezes, putting pressure on the surrounding rock. Corrosion Carbon Dioxide dissolves in rainwater, producing acid rain. This reacts with minerals inside certain rocks (e.g. limestone), causing them to be weakened and easily dissolved.

4 How are headlands and bays formed? Erosion on Hard Coastlines 1) Hard (e.g. chalk) and soft rock (e.g. boulder clay) are at right angles to the coastline. 2) Soft rock is eroded at a faster rate by hydraulic action and abrasion. 4) As the headland juts out to sea, it receives the full force of the waves energy. This allows the headland to be eroded slowly over time. 3) Over time, a bay is formed within the soft rock. The shape of the coastline reduces the energy forming constructive waves. This allows beaches to form. How are cave, arches and stacks formed? Headland 4) Overtime, the base of the stack is eroded by abrasion which then topples over in a storm to form a stump. 1) A cave is formed when hydraulic action widens the joints in the rock over time. 2) An arch is formed when hydraulic action and abrasion continue to erode the backwall of a cave all the way through the headland. 3)A stack is formed when the roof of the arch is weathered by freeze thaw action. This weakens it causing to collapse as a rock fall due to gravity. How are wave cut notches and platforms formed? 2) The top of the cliff is weakened by freeze thaw weathering. 4) Cliff collapses due to gravity as a rockfall. 1) Erosion from the sea (i.e. abrasion and hydraulic action) start to undercut the cliff base.. 5) The cliff slowly retreats back leaving a wave cut platform behind. 3) This wave cut notch increases in size until the weight of the cliff can no longer be supported.

5 How do rockfalls happen? Erosion on Hard Coastlines Process: Freeze thaw weathering is when water enters cracks between rocks and freezes. This causes the water to expand which puts pressure on the surrounding rocks. Over time, it weakens the rock causing it to break up. This causes rock to fall from the cliff face due to gravity as a rockfall. Landforms A scree slope of fallen rock is formed at the bottom of the cliff face. Erosion on Soft Coastlines SLUMPING Process: Slumping is a rapid movement of boulder clay that occurs on a curved slip plane. LANDSLIDES AND MUDFLOWS Process: A landslide is a rapid movement of boulder clay that occurs on a slip plane that is parallel to the cliff face. It happens when erosion from the sea undercuts the base of the cliff. This destabilises the cliff face causing the clay to slide down the cliff as a landslide. Landforms: An accumulation of sediment remains at the base of the cliff which is known as a scree slope. It happens when water percolates (soaks into) into the boulder clay until it becomes saturated with water making it heavy. The weight of the cliff above it forces the rock down towards the sea as a mud flow. Landforms: A step like cliff face is present after the slumping has occurred. Vegetation (originally from the cliff top) will also be present in patches on the cliff face.

6 Deposition: How are beaches formed? Swash Aligned Beach Waves approach the coastline and then break in parallel to the coastline Swash and backwash move sediment up and down the beach. Creates an even profile along the shoreline During storms, berms (ridges of sediment can form). Drift Aligned Beaches (longshore drift) 3)Backwash moves the material straight back down the beach to the sea. 2) Swash moves the material up the beach at an angle. 1) Prevailing wind direction moves waves onshore at an angle. 4) Material is picked up again and moved back up the beach as swash. 5) Backwash brings the material back down the beach again. 6)The sediment moves in a zig-zag motion along the beach. Over time, large amounts of sediment are moved along the beach. Deposition: How are spits and bars formed? e.g. Spurn Head, Holderness Coastline e.g. Slapton Ley, Devon How is a spit formed? 1. Waves carrying material are blown in the direction of the prevailing wind. 2. Longshore drift moves material along the coast. 3. Where the coastline changes direction, material is deposited in water sheltered by the headland. 4. The material builds upwards and outwards to form a spit. 5. A mud flat starts to develop in the sheltered water behind the spit due to less erosion. 6. Secondary winds can cause the end of the spit to curve forming a hooked end 7. The salt marsh develops on the mud flat in the sheltered water. How is a bar formed? 1. Waves carrying material are blown in the direction of the prevailing wind. 2. Longshore drift moves material along the coast. 3. Where the coastline changes direction, material is deposited in water sheltered by the headland. 4. The material builds upwards and outwards to form a spit. 5. The spit continues to grow across the bay area and joins to the headland to form a bar. 6. A lagoon is formed behind the bar. Over time, this is filled up with sediment to form land.

7 Coastal Management Why do some areas of the coast need protecting but not others? There are 4 Management Options for each section of coastline: Do nothing (let the coast erode naturally) Hold the line (defend the coastline to keep the coastline where it is at present) Advance the Line (build defences further out from the existing coastline to help reclaim lost land) Managed realignment (develop defences further inland and permit some coastal flooding) Not all coastlines can be protected as this would be highly expensive. There a variety of socio-economic reasons why seaside towns need to be protected. This includes where large numbers of people live and local businesses.(e.g. Bridlington).The Easington Gas Terminal also needs protecting because it is so important in providing gas for the UK whilst also providing jobs. The whole of the Holderness coast is vulnerable to erosion as it is made of soft rock. This means decisions are made about which bits to hold the line and which areas will have to be allowed to erode back. Shoreline Management Plan The aim of the Shoreline Management Plan is to identify which areas of coast require protection, and which don t. By looking at the coast as a whole, planners can make sure that any changes to one part of the coast will not impact another part of the coastline. Pevensey Bay: An example of Soft Engineering Definition: Working with the natural processes of sea and sand in a more environmentally sustainable way. Using the natural processes to bring about an intended effect. Name & Picture How does it reduce erosion? Advantages Disadvantages Beach Recycling Beach Replenishment As sediment moves due to longshore drift, some parts of the beach lose sediment whilst others gain sediment. To even this out, material is moved back to the areas where sediment has been lost. This is carried out after winter storms. Dredgers are used to take sand from the sea bed which is then sprayed onto the beach. This replaces lost beach material from longshore drift and produces a large beach. This causes more friction and reduces erosion. Adds to tourist amenity by making bigger beach Attractive no unsightly structures like hard engineering Works with the natural processes of the coast therefore more environmentally friendly Needs frequent renewal of more sand Does not protect cliff face against the energetic and destructive winter storm waves. Local people have the opinion that soft engineering is not as good as hard engineering. Beach Reprofiling This involves using bulldozers to push sediment up the beach. This changes the slope angle of beach from steep to gentle. This allows for more wave energy to be absorbed reducing erosion. Sometimes plants are placed at the back of the beach to soak up wave energy.

8 Holderness Coast: An example of Hard Engineering Definition: Controlled disruption of natural processes (e.g. erosion and longshore drift) by using man-made structures. Name & Picture How does it reduce erosion? Advantage Disadvantages Sea Wall (e.g. Hornsea) Curved sea walls reflect the energy of the waves back to the sea preventing erosion of the cliff. Protects the base of cliffs, land and buildings against erosion. Can prevent coastal flooding in some areas. Can be expensive to maintain as sea-walls are eroded over time. Rock Armour (e.g Hornsea) Absorb wave energy reducing the erosion of the cliff face. Cheaper than sea walls. Unsitely and reduces access to beach. Can be expensive to obtain and transport the boulders. Gabion (e.g. Hornsea) Absorb wave energy reducing the erosion of the cliff face. Easily installed and cheaper than sea walls. Not very attractive, needs frequent checking & repair, not easy for people to get over to get to beach, may contain rats nests Groyne (e.g. Hornsea) Reduces the rate of longshore drift allowing a large beach to develop. The because causes friction with waves reducing wave energy thus causing less erosion Allows a large beach to form encouraging tourism. Can be seen as unattractive. Costly to build and maintain Cliff Drainage (Mappleton) Pipes and drains are put into the cliff to remove water that causes slumping. Can be used on soft rocks effectively. Can cause erosion where water leaves the pipe into the sea. Can affect local wildlife Tetrapods (Japan) Absorb wave energy reducing the erosion of the cliff face. Can be built on site. Reduces transport costs. Isn t completed effecting at reducing erosion as some wave energy is not absorbed.

9 How can we protect the coast from sea level rise? Managed realignment Case Study: Wallasea Island, Essex What is managed realignment? Managed realignment involves the construction of new sea wall at a location behind existing sea wall. This allows the area between the old and new sea wall to become flooded forming a saltmarsh. The created saltmarsh helps reduce erosion and protects against sea-level rise. Case Study of managed realignment: Wallasea Wetlands, Essex, UK What has happened? With the coastal defences in the north of the island crumbling away, the government decided to realign (change the shape of) the northern part of the island by constructing a new embankment (wall) inland (further south) and allow the sea to further break through (breach) the old sea defences. How has it worked? The formed salt marsh provides a natural defence against flood tides and will be increasingly important as sea levels rise. Sea water is able to spread out over the salt marsh reducing the risk of flooding further inland. Reduced erosion will also take place as plants absorb wave energy. Has it been successful? Benefits: Farmland wasn t lost in the creation of the salt marsh. Few buildings were destroyed. Fisheries were improved Created 115 ha of saltmarsh for birds. It meant that they saved money that would have otherwise been uselessly spent on replacing the current sea defenses i.e. a new sea wall that would have cost around 1,000,000 per kilometre..

10 Case Study: How can we make the Holderness Coastline sustainable? What are the current pressures along the Holderness coastline? Farming related pollution Overfishing Footpath erosion Alternative sources of energy Overpopulation Tourism What is the ICZM and what are the aims? ICZM stands for Integrated Coastal Zone Management. It is a 100 page document informing planners on how to be sustainable along the coastline. Aims to reduce the pressures along the Holderness Coastline by encouraging sustainable practices. Sustainability: Meeting the needs of the people today without causing problems for future peoples. How is the ICZM along the Holderness Coast sustainable? ICZM Element Environmental sustainability Social Sustainability Economic Sustainability To encourage appropriate offshore wind / wave power generation Reduces amount of fossil fuels burnt which release greenhouse gases. This will help reduce the threat of global warming. Reduces energy prices as less money has to be paid on importing fossil fuels. It makes energy affordable for low income people. Provides jobs during the manufacture and maintenance of offshore wind and wave energy plants. To support schemes that have environmentally friendly farming techniques Farmers use less chemicals such as fertilizer and pesticides which cause water pollution. This helps keeps coastal waters clean. Food grown organically has a higher nutritional value due to higher vitamin and mineral content. People become healthier. Environmentally friendly techniques cost less to implement so farmers see larger profits which can help compensate loss of land through erosion. To ensure the continued viability of the inshore fishing industry Fish stocks remain high for all species allowing for biodiversity and maintenance of existing food webs. Provides people with a sustainable supply of different varieties of fish at low prices. Provides a balanced diet. Provides fishermen with long term job security as fish stocks are being sustained. To provide on-site information and education materials to educate and inform both visitors and local people. Prevents footpath erosion and trampling of plants. Bird species do not get disturbed by visiting tourists Local visitors centre to educate people about the wildlife at various coastal locations and how to protect it Profits made through tourism can be used to further conservation work in coastal areas.