Physical landscapes in the UK

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  • Created by: leo1223
  • Created on: 09-05-18 20:32
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  • Physical landscapes in the UK
    • Costal landscapes in the UK
      • Costal processes
        • Weathering processes
          • Mechanical weathering
            • Freeze-thaw weathering
              • 1. Only happens when temperature alternates above and below 0 degrees
              • 2. Water gets into rock through cracks
              • 3. When the water freezes it expands, which puts pressure on the rock
              • 4. When the water thaws, it contracts, which releases the pressure on the rock
              • 5. Repeated freezing and thawing widens the cracks and causes rocks to break up
          • Chemical weathering
            • Carbonation weathering
              • 1. Rainwater contains carbon dioxide, which makes a weak carbonic acid
              • 2. Carbonic acid reacts with rock that contains calcium carbonate, rock are then slowly dissolved by the acid
        • Longshore drift
          • 1. Waves follow the direction of the prevailing wind
          • 2. They usually hit the coast at a oblique angle
          • 3. The swash carries the sediment up the beach depositing some
          • 4. The backwash then carries sediment down the beach at right angles, back towards the sea
          • 5. Overtime sediment travels in a zigzag along the coast, moving sediment along the beach
        • Erosion
          • Abrasion
            • Eroded particles in the water scrape against rock, removing small fragments
          • Attrion
            • Eroded particles in the water smash into each other and break into smaller fragments which rounds their edges off
          • Hydraulic action
            • Waves crash against rock and compresses the air in the cracks, this puts pressure on the rock. Repeated compression widens the cracks which breaks up the rock into smaller fragments
          • Solution
            • Weak carbonic acid in seawater dissolves rock like chalk and limestone
        • Deposition
          • 1. Deposition is when sediment being carried by the sea water is deposited or dropped on the coast
          • 2. Coasts are built up when the amount of deposition exceeds the amount of erosion
          • 3. The amount of sediment deposited on area of coast is increased when
            • There is lots of erosion elsewhere on the coast, which means lots of sediment is available
            • There is lots of transportation of sediment into the area
          • 4. Low  energy waves carry sediment to the coast but they are not strong enough to take a lot of sediment back, these are know as constructive waves, which means there is lots of deposition and transportation and little erosion
        • Transportation
          • Solution
            • Soluble materials dissolve in the water and are carried along
          • Traction
            • Large particles like boulders are pushed along the sea bed by the force of the water
          • Suspension
            • Small particles like silt and clay are carried along by the water
          • Saltation
            • Small rocks and particles bounce along the seabed by the force of water
          • Longshore drift
            • Material is transported along coasts by longshore drift
        • Waves
          • Factors that affect size and power of waves
            • Wind
              • A strong wind gives large, powerful waves
              • Weaker winds form constructive waves
              • Strong winds form destructive waves
            • Fetch
              • The greater the fetch, the bigger and more powerful the waves
              • Shorter fetch make constructive waves
              • Longer fetches make destructive waves
          • Destructive waves
            • Strong backwash
            • Weak swash
            • High frequency
            • High and steep
            • More sediment is removed from the beach than placed on the beach
          • Constructive waves
            • Strong swash
            • Weak backwash
            • More sediment is deposited than eroded
            • Low and long
            • Low frequency
      • Costal landforms
        • Formations caused by erosion
          • Headland
            • Contains more resistant rock than the rock found in bays, this rock is eroded slowly forming a headland, headlands have steep sides
          • Bay
            • Contains less resistant rock than the rock found in headlands, this rock is eroded quickly forming a bay, bays have a gentle slope
          • Headlands are eroded to form caves, arches, stacks and stumps
            • 1. Headlands are made of resistant rock however they have weaknesses like cracks
            • 2. Waves crash into headlands and enlarge the cracks - mainly by hydraulic action and abrasion
            • 3. Repeated erosion and enlargement of cracks causes a cave to form. This cave is continually eroded
            • 4. Continued erosion deepens the cave until it breaks through the headland - forming an arch
            • 5. Erosion continues to wear away the rock supporting the arch, until it eventually collapses
            • 6. This forms a stack - an isolated rock that's separate from a headland e.g. Old Harry in Dorset
            • 7. The stack is eventually worn down after repeated erosion to give a stump, which can be covered by the water at high tide, e.g. Old Harry's Wife in Dorset
          • Cliff retreat as a result of erosion, weathering and mass movements
            • 1. Waves cause most erosion at foot of cliff
            • 2. This forms a wave-cut notch, which is enlarged by erosion, making the cliff above the notch unstable
            • 3. The part of the cliff above sea level is also affected by mechanical and chemical weathering process. This makes the cliff more unstable and it eventually collapses
            • 4. The collapsed sediment is washed away and a new wave-cut notch starts to form
            • 5. Repeated collapsing results in the cliff retreating
            • The rate of retreat is affected by:
              • The geology of the cliff
                • soft rock retreats quickly where as hard rock is eroded over thousands years
              • Vegetation
                • Cliffs covered in vegetation are more stable so they are eroded easily and retreat more slowly
          • Mass movements
            • Cliff collapse are mass movements (the shifting of rock and sediment). They happen when the force of gravity acting on a slope is greater than the force supporting it e.g. when the notch has made the cliff above unstable
            • Three types of mass movements
              • Slides
                • Sediment and rock shifts in a straight line
              • Slumps
                • Sediment and rock shifts with a rotation
              • Rockfalls
                • Sediment and rock shift vertically
        • Formations caused by deposition
          • Spit
            • Spits are beaches that stick out onto the sea, they are formed by longshore drift
          • Bar
            • A bar is formed when a spit joins two headlands together
          • Salt marsh
            • The sheltered area behind the spit accumulates material, forming vegetation and eventually a salt marsh
      • Mangement stratergies
        • Hard engineering
          • Sea wall
            • Benefits
              • It prevents erosion of the coast. It also acts as a barrier to prevent flooding. Also the sea wall can act as a pathway for the public
            • Disadvantages
              • It creates a strong backwash, which erodes under the wall. Sea walls are very expensive to build and to maintain
            • What it is?
              • A wall made out of concrete that reflects waves back to the sea
          • Rock amour
            • Benefits
              • The boulders absorb wave energy and reduce erosion and flooding of the coast
            • Disadvantages
              • Boulders can be moved around the strong waves, so they need to be replaced
            • What it is?
              • Boulders that are piled up along the coast
          • Groynes
            • Benefits
              • Groynes create wider beaches as they prevent sediment from leaving the beach by longshore drift
            • Disadvantages
              • They starve beaches further down the coast of sediment, making them narrower
            • What it is?
              • Wooden or stone fences that trap material transported by longshore drift
        • Soft engineering
          • Beach nourishment
            • Benefits
              • Creates wider beaches which protects against erosion and flooding
            • Disadvantages
              • Taking material from seabed can kill organisms like corals. Its a very expensive, it has to be repeated
            • What it is?
              • Sediment (sand) from elsewhere is added to beaches to counteract longshore drift
          • Dune regeneration
            • Benefits
              • Sand dunes provide a barrier between inland and sea. Wave energy is absorbed by dunes
            • Disadvantages
              • The protection is limited to a small area. Nourishment is very expensive.
            • What it is?
              • Creating or maintainingby either nourishment or by planting vegetation
          • Marsh creation (managed retreat)
            • Benefits
              • The vegetation helps reduce the speed of waves. Prevents flooding and erosion
            • Disadvantages
              • Marsh creation isn't useful where erosion rates are high because marsh can't establish itself.
            • What it is?
              • Planting vegetation in mudflats along the coast
      • Case study: Holderness coast
        • Social factors
          • Homes near cliffs are at risk of collapsing into sea
          • Acessibilty has been affected because roads near cliff tops are at risk of collapsing into the sea
        • Economic factors
          • Property prices fallen sharply as properties are at risk from erosion
          • Bussiness on the coast are at risk from erosion, people will lose jobs
        • Environmental factors
          • Some sites of scientific interest are at risk for example the Lagoons are at risk from being destroyed due to the erosion of a bar separating the sea and the lagoons
        • Management strategies
          • 4.7km sea wall protects Bridlington from flooding and erosion as well as wooden groynes
          • At Hornsea there is a sea wall, wooden groynes and rock amour that protect the village from erosion and  flooding
          • Rock groynes built at Mappleton costing £2 million
          • The eastern side of Spurn Head is protected by groynes and rock armour
        • Main reasons for rapid erosion
          • The cliffs are made of boulder clay which is easily eroded, its likely to slump when its wet causing the cliffs to collapse
          • The Holdernesscoast has naturally narrow beaches, which gives less protection
          • The Holdernesscoast faces prevailing wind direction, which brings waves from the north east, the long fetch means these waves are  highly erosive waves
    • River landscapes in the UK
      • Fluvial processes
        • Erosion
          • Hydraulic action
            • The force of the water breaks rock particles away from the river channel
          • Abrasion
            • Eroded rocks picked up by the river scrape and rub against the channel channel wearing it away
          • Attrition
            • Eroded rocks picked up by the river smash into each other and break into smaller fragments. Causing their edges to become rounded off
          • Solution
            • River water dissolves some types of rock e.g. chalk and limestone
        • Transportation
          • Traction
            • Large particles like boulders are pushed along the river bed by the force of the water
          • Suspension
            • Small particles like silt and clay are carried along by the water
          • Solution
            • Soluble materials dissolve in the water and are carried along by the water
          • Saltation
            • Small particles and pebbles bounce along the river bed by the force of the water
        • Deposition
          • 1. Deposition is when a river drops the eroded sediment it's transporting
          • 2. It happens when a river slows down
          • Reasons for deposition
            • Volume of water in the river falls
            • The river reaches its mouth
            • The water is shallower, e.g. on the inside bend of a meander
            • The amount of eroded sediment in the water increases
      • River lanforms
        • Formation of landforms as a result of erosion
          • Waterfalls
            • Waterfalls are found in the upper course, Waterfalls form where a river flows over an area of hard rock followed by an area of soft rock
          • Interlockingspurs
            • The river in the upper course isn't powerful enough to erode sideways, which creates V-shaped valley. The high hillsides that form the V-shaped valley that interlock are know as interlocking spurs
          • Gorges
            • A gorges are found in the upper course, gorges are formed from waterfalls retreating overtime leaving behind a steep gorge
        • Formation of landforms as a rebut of erosion and deposition
          • Meanders
            • In the middle and lower courses meanders develop, meanders are large bends in a river formed by erosion and deposition of sediment
          • Ox bow lakes
            • An ox-bow lake is formed by the further erosion of a meander causing a section of the river to become isolated from the channel
        • Formation of landforms as a result of deposition
          • Levees
            • Levees are natural embankments along the edges of a river channel, levees are formed when a flood occurs and deposits the heaviest sediment along the river channel. As more floods occur, the sediment builds up, leaving natural embankments known as levees
          • Flood plains
            • A flood plain is a wide valley floor on either floor which occasionally gets flooded
      • Management strategies
        • Hard engineering
          • Dams and Reservoirs
            • Benefits
              • Reservoirs store water and release it slowly, reducing the risk of flooding, the water in the reservoir can be used to produce hydroelectric power
            • Disadvantages
              • Dams are very expensive to build. Creating a reservoir can flood existing settlements
            • What it is?
              • A dam is a wall built across a river. A reservoir is an artificial lake formed behind a dam
          • Channel straightening
            • Benefits
              • Water moves out of the area more quickly because it doesn't have to travel as far, reducing the risk of flooding
            • Disadvantages
              • Flooding may happen downstream of the straightened channel instead, as flood water is carried there faster
            • What it is?
              • The river's course is straightened, meanders are cut out by creating artificial straight channels
          • Man-made levees
            • Benefits
              • The embankments mean the river channel can hold more water, which reduces the risk of flooding. They are also quite cheap
            • Disadvantages
              • If the levees break, it can cause catastrophic flooding
            • What it is?
              • Man-made embankments along both sides of the river
        • Soft engineering
          • Flood plain zoning
            • Benefits
              • The risk of flooding is reduced as impermeable surfaces are created, more permeable surfaces are available
            • Disadvantages
              • Expansion of urban areas are limited
            • What it is?
              • Restrictions prevent building on parts of a flood plain that are likely to be affected by a flood
          • Flood warnings
            • Benefits
            • Disadvantages
              • Untitled
            • What it is?
          • Planting trees
            • Benefits
            • Disadvantages
            • What it is?
          • River restoration
            • Benefits
            • Disadvantages
            • What it is?
      • Cross profiles
        • Upper course
          • Steep gradient
          • V-shaped valley, steep sides
          • Narrow, shallow channel
          • Waterfalls  and gorges
        • Lower course
          • Gentle gradient
          • Very wide, almost flat valley
          • Very wide, deep channel
          • Flood plains and levees
        • Middle course
          • Medium gradient
          • Gently sloping valley sides
          • Wider, deeper channel
          • Meanders and ox-bow lake
      • River discharge
        • Peak discharge
          • The highest discharge in a period of time
        • Lag time
          • The delay between the peak rainfall and peak discharge
        • Factors affecting river discharge
          • Amount of rainfall
          • Impermeable rock
          • Hot, dry conditions
          • Previously wet conditions which prevent water from infiltrating saturated soil
          • Amount of vegetation
      • Flooding
        • Physical factors
          • Heavy rainfall
            • After heavy rainfall, there is a lot of surface runoff which increases discharge quickly, increasing the likelihood of a flood
          • Geology
            • When a river is in an area of permeable rock, more water is taken in by the rock instead of the river. This means there is naturally less runoff, however if a river is surrounded by an area of impermeable rock, water isn't taken up by the rock, and more water is transported to the river. This means there is more surface runoff so the risk of flooding is higher
          • Prolonged rainfall
            • After a long period of rain, the soil becomes saturated, any futrther rainfall cannot infiltrate the soil which increases surface runoff   this increases the likelihood of a flood
        • Human factors
          • Deforestation
            • Trees intercept rainwater, trees also take up water from the ground. This means that less water reaches the river channel decreases the chances of a flood occurring . However the deforestation occurring means the volume of water that reaches the river channel has increased, increasing the likelihood of a flood
          • Building construction
            • Buildings are often made out of impermeable materials e.g. concrete, and are surrounded by tarmac roads which are also impermeable.  Impermeable surfaces increase surface runoff resulting in larger volumes of water being transported to the river channels faster, increasing the likelihood of a flood

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