Rivers And Coasts Flashcards
Processes of erosion
Corrasion/Abrasion: When a wave throws small pebbles against the cliff face knocking off small parts of the cliff causing undercutting
Attrition: Particles being transported by the hitting against one another reducing their size and making them more rounded
Solution: Seawater causes the the rock to dissolve away from the sea bed or cliffs
Processes of transportation
Solution: Seawater causes the rock to dissolve away from the sea bed or cliffs
Suspension: Small particles such as silts and clays are suspended in the oceans waves
Saltation: Where small pieces of shingle or large sand grains are bounced along the sea bed
Traction: Where pebbles and larger materials are rolled along the seabed
Definition of deposition
A river dropping the load it was carrying from a decrease in its velocity
How does a waterfall form
When a layer of soft rock beneath hard rock gets eroded by the river making a step in the riverbed. Eventually this becomes deeper until it becomes a waterfall
Methods of flood management
Hard engineering strategies: Damns/Levees
Soft engineering strategies: Afforestation/Washlands
Hard engineering example
Dams allow water to be stored rather than surge downstream and cause floods there. They can also be used for water supply, hydroelectricity and recreation
How can a flood impact the environment
The chemicals and waste from the river would disperse across the surrounding area causing pollution and resulting in the loss of habitation for local animals
Causes of flooding in the river Parrett
Physical causes: Low lying land, severe winter storms and high tides
Human causes: Rivers were full of silt, houses built on the floodplains
Explain constructive & destructive waves
Constructive waves: Strong swash, weak backwash
Destructive waves: Strong backwash, weak swash
How does a wave-cut platform form
The sea attacks the base of the cliff which forms a wave-cut notch. The notch increases in size until the base fully collapses. The backwash takes away the rubble leaving behind the wave-cut platform
Define longshore drift
Occurs when the waves hit the beach at an angle. The swash moves the material up the beach diagonally but the backwash draws directly downwards
Why is coastal defence is needed
- People live near the coast
- Economic importance
- Sea level is predicted to rise by 0.5-1m as climate change continues
Groynes
Long fences made of heavy wood
Advantages: It lasted about twenty years
Disadvantages: Eventually decayed and needed replaced
Unsustainable
Gabions
Wire boxes filled with stones
Advantages: Works better than walls or other methods
Disadvantages: Overtime they have to be replaced which is expensive
Sustainable
Sea Wall
Curved concrete wall
Advantages: The old wall protected Newcastle for many years, the new wall is curved so the energy travels back into the ocean
Disadvantages: Reflected wave energy erodes the beaches the wall is still impacted by energy
Unsustainable
