Coastal system and landscape Flashcards
What are the 4 shores on the beach in order?
Cliff edge - Backshore - Foreshore - Nearshore - Offshore Sea
What is backshore?
Area between high water mark and cliff or barrier
What is foreshore?
Area between high water mark and low water mark
What is nearshore?
Area between low water mark and point where waves cease to have influence
What is offshore?
Area beyond where waves cease to have impact upon seabed
What is nearshore?
Area extending from higher water mark to area where waves begin to break
What are the 3 parts of nearshore (zones)?
- Swash zone
- Surf zone
- Breaker zone
What is the swash zone?
Area where a turbulent layer of water washes up the beach after break of wave
What is the surf zone?
Area between point where waves break (foamy, bubbly surface) and where waves wash up the beach (swash zone)
What is the breaker zone?
Area where waves approaching coastline begin to break (depth of 5-10m)
What are inputs of a coastal system?
- Energy from waves, winds, tides and sea currents
- Sediment
- Geology of coastline
- Sea level change
What are components of a coastal system?
- Erosional landforms and landscapes
- Depositional landforms and landscapes
What are outputs into a coastal system?
- Dissipation of wave energy
- Sediment removal
- Accumulation of sediment above tidal limit
What 4 factors provide energy in a coastal system?
- Waves
- Wind
- Tides
- Currents
What 3 factors affect the energy of a wave?
- Strength of wind
- Fetch
- Duration of wind
What is the fetch?
Distance of open water over which a wind blows uninterrupted by major land obstacles
What are compoents of a wave?
- Crest (top)
- Trough (bottom)
- Wavelength (distance between to crest)
- Wave height (distance between crest and trough)
What is the wave period?
Time for one wave to travel one wavelength
What is swash?
Rush of water up the beach
What is backwash?
Water running back down the beach
Explain the wave movement as it travels towards the beach
1) Friction with seabed slows down base of wave
2) Crest rises, velocity and wavelength decrease
3) This increases the elliptical orbit
4) Wave steepens until wavelength: wave height of 7:1
%) Water swashes up the beach then backwashes down
What are the 2 types of wave?
- Constructive
- Destructive
What are constructive waves?
- Low wave height
- Long wavelength
- 6/8 per min
- Stronger swash than backwash (material moves up beach)
What are destructive waves?
- High wave height
- 10/14 per min
- Stronger backwash than swash (more sediment removed)
What can constructive waves lead to formation of?
Ridges (berms)
What can destructive waves lead to formation of?
Storm beach
How do destructive waves create negative feedback?
They move material back down the sea - reducing the angle of the slope which encourages constructive waves
What occurs when waves meet a headland?
Wave refraction
What is wave refraction?
- More drag in shallow water near headland and speeds up in front of bay due to deeper water
- Causes wave to bend as energy if waves becomes focused on headland
- Low energy waves spill into bay creating deposition
What is current?
Permanent or seasonal movement of surface water in seas and oceans
What are the 3 types of current?
- Longshore currents
- Rip currents
- Upwelling
What are longshore currents?
Waves approach beach at angle, this generates a flow of water running parallel to the coastline
What are rip currents?
- Strong currents moving away from shoreline
- Develop when sea water is piled up along coastline by incoming waves
What is upwelling?
- Movement of cold water from deep in ocean towards the surface
- Replaces warm surface water and it is rich in nutrients
What are tides?
Periodic rise and fall in the level of the sea due to gravitational pull of sun and moon
What are the 2 types of tide?
- Spring tide
- Neap tide
How is a spring tide created?
When earth, moon and sun are in straight line this produce the largest bulge and highest tide
How are tides created?
- Moon pulls water towards it creating high tide and a bulge is formed on the opposite side is formed as well
- As moon orbits earth the tides change
How is a neap tide created?
- When moon and sun are positioned at 90 degrees 4 bulges
- Lowest monthly tide (10-30% lower than average)
What factors affect tide in individual locations?
- Morphology of seabed
- Proximity of land masses
- Coriolis effect
- Tidal range
What is tidal range?
Difference in height of water at high and low tide
What are tidal or storm surges?
When meteorological conditions give rise to strong winds which produce water levels higher than high tide
What area in Britain experiences storm surges?
East coast
What are low energy coastal?
Coastline where wave energy is low and rate of deposition exceeds rate of erosion
What are high energy coasts?
Coastline where strong, steady prevailing winds create high energy wave and rate of erosion is higher than deposition
What are typical landforms of low energy coasts?
Beaches and spits