Physical landscapes in the UK Flashcards
What type of coastline has suitable conditions for the formation of erosional landforms
Steep cliffs as it indicates hard resistant rock
Explain the formation of a wave-cut platform
- It is made by processes of erosion and weathering
- Soft rock erodes quickly making sloping cliffs and hard rock form steep cliffs
- Hydraulic action and abrasion weaken the base of a cliff creating a wave cut notch
- Weathering weakens the top of the cliff
- The top of the cliff eventually becomes unstable and collapses
- The cliff has retreated
- A wave cut platform is a gentle sloping surface of a cliff extending out to sea
What is the case study for coastal management schemes
MAPPLETON
- two hard engineering process
- rock armour and gabions
- was effective at protecting Mappleton
- but south to Mappleton erosion has increased as they do not have any coastal defences
How is a coastline of headlands and bays formed?
- Due to coastal erosion, hydraulic action and abrasion
- Headland is hard rock so is resistant and erodes slowly
- Bays are made of soft rock so easily erodes
What are the hard engineering defences for coasts
- Sea walls
- Rock armour
- Gabions
- Groynes
Rock armour
- Cheaper than a sea wall and easier to maintain
- Can be used for fishing
- Different from local geology
- Can be expensive to import rocks
Groynes
- Can cause chronic groyne syndrome further along the beach
- Builds a wider beach, more tourists
- Look unattractive
Gabions
- Cheap
- Absorbs wave energy
- Not very strong
-Looks unnatural
Sea walls
- Deflect and absorb wave energy back to the sea
- Create a promenade for people to walk along
- Expensive and require regular repairs
Soft engineering defences for coasts?
- Beach nourishment
- Dune regeneration
- Reprofiling
Beach nourishment
- Blends into existing beach
- Larger beach = more tourist
- Needs to be constantly replaced
- Sand has to be brought in from somewhere else
Dune regeneration / nourishment
- Relatively cheap
- Maintains a natural looking coastline
- Can be damaged by storm waves
- Fenced off areas is not popular for public
Reprofiling
- Cheap and simple
- Reduces energy of waves
- Only works when wave energy is low
- Needs to be repeated constantly
Managed retreat
- Cheap option
- Creates a salt marsh, good for habitat and natural defence against erosion
- Land is lost to the sea
- Land owners must be compensated
What is freeze - thaw weathering?
Water enters a crack in the rock
Water freezes and expands widening the crack
Ice melts and water goes further into the crack
Process repeats until the rock splits
What are the types of mass movement?
- Landslide
- Rockfall
- Mudflow
- Rotational slip
What is traction?
pebbles and larger materials are rolled across the sea floor
What is saltation?
small pieces of shingle are bounced along the sea bed
What is suspension?
small particles are suspended in the flow of water
What are deposition land forms of the coast
- A spit
- A bar
- A beach
A spit
- Sediment is carried by long shore drift
- When there is a change in direction of the coastline deposition occurs = spit
- If the wind direction changes a hooked end can form
- A salt marsh is formed behind a spit
A bar
- Where a spit travels across a bay
- joins two headlands together
- Can trap shallow lakes behind, forming a lagoon
What is the feature formed on a meander due to deposition
A slip off slope
At the fastest point of a meander what process happens
Erosion on the outer bend of the river forms a steep river cliff
At the slowest point of a meander what process happens
Deposition on the inside of the bend, a slip off slope is formed
Physical factors which cause increased river discharge?
- Precipitation
- Relief
- vegetation
Human factors which cause increased river discharge?
- Impermeable rock surface
- Land use (Agriculture)
- Removal of trees and hedges
Hard engineering defences for rivers?
- Dams and reservoirs
- River straightening
- Embankments
- Flood relief channels
Dams and reservoirs
- Can be used to create energy
- Very effective
- Can harm fish and wildlife
- Land has to be flooded
- Expensive
River straightening
- More water can be held in the channel
- Reduces risk of flooding
- Dredging needs to be done more regularly
- Speeding up the channel increases risk of flooding elsewhere
Embankments
- Cheap
- Allows more water to be held without it flooding
- Looks unnatural, eyesore
Flood relief channels
- Reduces flooding as removes water
- Expensive
- Could also flood if water rises
Soft engineering defences for rivers?
- Flood warnings and preparation
- Floodplain zoning
- Managed retreat
- River restoration
Flood warnings and preparation
- People have time to protect their properties and evacuate
- Possessions can be saved
- Flash floods happen to quickly
- People may not have access to the warning
- Do not stop flooding at all
Floodplain zoning
- Most expensive and valuable buildings are at least risk of flooding
- Less damage meaning less insurance claims
- Planners have a hard decisions
- Not always possible to change existing land uses
Upper course of a river
The channel is narrow and shallow as there is not much water, water is flowing downhill
Lower course
Less erosion than middle course, so the channel is its widest and deepest
Erosional landforms of a river
- waterfall and gorge
- Interlocking spurs
Waterfall and gorges
- Soft rock is eroded hard rock is not creating a step
- hard cut is undercut by the soft rock eroding forming an overhang
- A plunge pool is created by erosion
- Overhang becomes unsupported and collapses
- Process continues and retreats upstream
- == Gorge
What is the lag time on a hydrograph
The time between peak rainfall and peak discharge
How do you work out discharge?
Velocity x area
What does a short lag time mean about a river
Flooding is more likely
What does a steep rising limb mean on a hydrograph
A short lag time
so more likely to flood
What does a gradual rising limb mean on a hydrograph
A long lag time
less likely to flood
