Section 3

• Coastline is the outline of land, where the land meets the sea
• Constructive waves:

  • Long wavelength and low wave height
  • Strong swash and gentle backwash = deposit material
• Destructive waves:

  • Short wavelength and high wave height
  • Weak swash and strong backwash = erosion
  • Powerful
• Fetch is the distance of water over which the wind blows
• Swash is the movement of water uo the beach
• Backwash is the water that rushes flows back to the sea
• Infiltration is when water enters the ground
• Saturation are rocks full of liquid
• Impermeable rocks don't allow water to pass through them
• Permeable rocks allow water to pass through them
• Slip plane is a line of weakness along which movement occurs
• Erosion is the wearing away or removal of rock. Erosion attacks the base of the cliff
• Erosion:

  • Hydraulic action (force of waves hitting the cliff which creates air bubbles which are pushed into the cracks of the cliff = removal of material)
  • Abrasion (sediment in hits against cliff)
  • Corrosion (chemicals in water dissolve cliff)
  • Attrition (material in sea crash into each other = smaller, smoother, rounder pieces)
• Weathering is the breakdown of rocks caused by the day-to-day changes in the atmosphere. Weathering attacks the to of the cliff
• Weathering: Freeze-thaw (water collects in cracks, at night this freezes and expands = crack gets larger, water melts through the day, process repeats, rock weakens and breaks) Biological weathering ( plant roots grow in cracks of rock and bresk them apart) Carbonation (carbon dioxide and sulphur dioxide mix with rainwater to produce acid rain which reacts with rock)
• Transportation:

  • Longshore drift (zigzag movement of transported material along the coastline, its transported in direction of the prevailing wind)
• Deposition is the dropping off of material carried by the water
• Mass movement is the downhill movement of material caused by gravity and happy due to erosion and weathering
• Mass movement

  • Rotational slump and landslide -> heavy rain infiltrates permeable rock - rock becomes unstable and line of weakness forms, land moves downhill along line of weakness, a curved line of weakness forms, a straight line of weakness forms
  • Rockfall -> freeze-thaw weakens rock at top of cliff, weakened rocks fall to base of cliff, material that collects at the bottom of the cliff is called a scree slope
• • Wave cut platform -> waves erode base of cliff between high and low tide levels due to hydraulic action and abrasion = wave cut notch and a overhanging cliff, further erosion = notch gets larger = overhanging cliff becomes unstable, overhanging cliff eventually collapses leaving a wave cut platform, the cliff retreats
• A headland is a cliff that sticks out into the sea. A bay is an indentation in the coastline between headlands.
• Headland and bay -> Discordant coastlines with different rock types will erode at diff speeds, hard Rock (granite) erodes slower creating headlands, soft rock (clay) will erode more quickly creating bays, bays are sheltered = deposition = beaches are formed
• Cave, arch, stack -> erosion attacks a line of weakness in the cliff = cave, continued erosion =back of cave eroded = arch, weathering weakens top of arch = unstable, it eventually collapses = stack, stack is eroded from the base by the sea and weakened at the top by weathering = stump
• 1.Longshore drift transport material along the coastline in a zigzag pattern. 2. Where there is a sudden bend in the coastline, thewaves lose energy = material is deposited. 3. Continued longshore drift and deposition, deposits material out to sea = spit. 4. Strong winds and waves curve the end of the spit = recurved end.

  5. The area behind the spit is sheltered from waves = low energy = deposition. Saltmarshes and mud flats are common here. They attract lots of wildlife.
• A bar is formed when a spit joins 2 headlands together. A lagoon forms behind the bar.
• A tombola is formed when a spit joins to an island.
• Beach -> deposits of sand and shingle at the coast, found on coast between high and low water mark, formed by constructive waves depositing material 
• Sand dunes -> mounds of sand at the back of the beach, sand is moved by the wind, it gets trapped by obstacles and sand us deposited, overtime it gets vegetated and larger = embryo dune, dunes get larger the further inland
• The UKs coastline I'd at risk of erosion. To prevent this, shoreline management plans (SMPs) have been put in place:

  • Advance the line -> build new defence structures (very high land value)
  • Hold the line -> maintain/improve existing coastal defences (high land value)
  • Managed retreat -> allow the sea to flood the land and build newsea defence islands (low land value)
  • Do nothing -> leave land to erode/flood (very low land value)
• Managed retreat -> deliberate decision to allow the sea to floor an area of low-value land. People are evacuated, buildings demolished and any existing sea defence us removed, the sea floods the land and salt marshes develop which absorb the energy of future waves, new flood defences can be built in high-value land behind the salt marshes
• Holderness coastline landforms: •Flamborough head is a resistant rock that's formed a headland, the cliffs are eroded by hydraulic action, abrasion and solution, a wave cut platform us formed as the cliff retreats

  •spurn point is a sand and shingle spit, 5.5km long stretching across the mouth of Humber estuary, spurn point is made up of material that's been transported along the coast from further north

  • mappleton cliffs are made of easily eroded boulder clay that is moved southerly and often deposited at the spurn point
• Hard engineering is using man-made, artificial structures to prevent erosion and flooding. They're more effective, long lasting and less maintaining thsn soft engineering, however more expensive and less natural/environmentally friendly
• Sea wall (hard engineering) -> a strong concrete wall in front of the cliff that absorbs the waves energy, a curved sea wall reflects the wave back to the sea. += effective, long lifespan, tourists like to walk along it. -= expensive to build and maintain, looks unnatural.
• Rock armour (hard engineering) -> large rocks placed in front of the cliff or settlement, that absorbs the waves energy. += effective, long lifespan, cheaper, more natural and easy to build/maintain than a sea wall. -= expensive, acces to the beach can be difficult, can become slippery and dangerous.
• Gabion (hard engineering) -> a wire cage filled with rocks that are placed infront of the cliff or seaside settlement that absorbs the waves energy. += effective, long lifespan, cheaper and easier to build and maintain than rock armour/seawall. -= sea water erose metal cages = broken gabion which can be dangerous to tourists, more expensive than soft engineering
• Groynes (hard engineering) -> Wood or rock fences built out into the sea, they trap sediment transported by longshore drift and make the beach larger. += beaches become larger = waves lose energy as they rush up the beach = less erosion, big beaches boost tourism. -= prevent sediment reaching beaches further along the coastline = problem is shifted instead os solved, more expensive than soft engineering's
• Off-shore, break-water (hard engineering's) -> stone walls built up in the beach parallel to the coastline. += reduce energy of waves and help deposition occur = bigger beaches. -= can be expensive and can interfere with boats.
• Soft engineering uses natural, environmentally friendly methods to prevent flooding. Often cheaper than hard engineering but need more maintenance and has a short lifespan.
• Beach nourishment (soft engineering) -> adds sediment to the beach to make it wider = acts as a barrier from the waves = reduces erosion and flooding. += cheap and easy to maintain, natural looking, bigger beaches =more tourism. -= short lifespan, constant maintenance
• Beach reprofiling (soft engineering) -> material removed by longshore drift or destructive waves is returned to the beach = prevents beach getting smaller. += cheap and easy to maintain, natural appearance, bigger beaches = more tourism. -= short lifespan, constant maintenance.