3.2.1 Coastsl Systems. Coastal Sources Of Energy Flashcards
What energy refers to at a coast?
At the coast energy refers to the power behind any change or transfer in the system
What is the main source of energy at a coast?
The main source of energy at the coast is the waves
Waves are mainly generated by wind
They can be caused by tectonic activity but this is much less regular
How high and low tidal range affects the coast?
A high tidal range such as in the Bristol Channel, means that waves only reach a particular part of the cliff for a small amount of time, and less energy is focussed on that spot
A low tidal range such as in the Mediterranean, means that waves will be concentrated on a small part of the cliff for longer, increasing the energy directed at that point
Explain what high energy coastline is and what are its main features
High energy coastlines are those that face powerful waves for most of the year
Erosion exceeds deposition at high-energy coastlines and the landforms reflect this such as headlands with arches and caves eroded into them and wave cut platforms
Explain what low energy environments are and outline its main features (landforms)
Low energy environments are those where the waves are less powerful and the coast is more sheltered
Deposition exceeds erosion at these coastlines creating beaches and spits
What are the two main types of waves
Constructive and destructive
Outline formation, wave form , break characteristics and affect on beach profile of constructive wave
(Formation) Distant weather systems, calm local weather, short fetch
(Wave form) Long wavelength, low, spilling waves
(Break characteristics) Strong swash, weak backwash
(Beach) Build up the beach with a gentle beach profile
Outline formation, wave form, break characteristics, beach of the destructive wave
(Formation) Local storms, strong winds, high fetch
(Wave form) Short wavelength, high, plunging waves
(Break characteristics) Weak swash, strong backwash
Beach is lost and a steeper beach profile is likely in the short term
Outline the process of wave refraction
Waves bend towards the headland as the water depth becomes shallower more quickly.
This concentrates the energy at the headland and reduces the amount of energy reaching the bay.
Wave refraction changes the amount of energy reaching the shore on a small local scale.
Wave energy concentrates at the headland and increases the rate of erosion.
Outline some of the sources of coastal sediment
Most coastal sediment is brought to the shore by rivers
Cliff erosion is also an important source of sediment at most coastlines
Where coastlines are retreating by a few metres a year there is a large input of sediment to the coastal zone
Wind can also transport sediment to the shore and this can lead to the build up of sand dunes
In high latitude coastal areas glaciers break off into the sea and sediment that was trapped within the ice is deposited at the coastal zone
Outline main features of sediment cell and their context in UK
Sediment cell is a stretch of coastline bordered by two headlands where the movement of sediment is contained.
They can be considered a closed system as most sediment movement is contained within the cell
There are 11 sediment cells around the UK coastline
Sediment cells can be divided into sub cells where the inputs (sources), stores (sinks), transfers and outputs within the system can all be identified
Explain what sediment budget is and a concept of dynamic equilibrium in the context of coastal system
The sediment budget is the balance between the inputs and outputs of sediment in the system
Coastal systems should be in a state where the sediment budget is in a state of dynamic equilibrium
However, human activity and natural changes like climate change can disturb the state of dynamic equilibrium.
