Systems And Processes In Coasal Environments Flashcards
Define erosion
The wearing away of surface by the mechanical action of glaciers, rivers, wind and waves
Define fetch
The distance of open water a wind blows uninterrupted which helps determine the size and energy of waves reaching the coast
Define mass movement
The movement of material downhill under the influence of gravity and assisted by rainfall
Define weathering
The breakdown or decay of rock that remains in situ until later moved by an erosion all process
What are the 4 main sources of energy in coasts
Wind, waves, tides and currents
When wind speeds are high and uninterrupted…
Waves are stronger
What type of wind encourages longshore drift
Prevailing wind direction
One type of wind erosion
Abrasion
3 characteristics of waves
Height, length and frequency
Constructive waves
Low wave heights
Long wavelength
Low frequency
Strong awash
Weak backwash
Destructive waves
High wave hieght
Short wavelength
High frequency
Strong backwash
Weak swash
Wave refraction
As waves approach coast the become more parallel
It drags the shallow water to th e headland
Increases wave speed and height
concentrate on headlands causing greater erosion
Longshoreman currents
Approach coast at an angle moving water along surf zone and transporting sediment
Rip currents
Strong currents moving away from shoreline - extremely hazardous
Upwelling
Movement of cold water to the surface replacing warm water creating nutrient rich cold oceans
What are tides
The period rise and fall of the level of the sea n response to the gravitational pull of the sun and the moon
How are spring tides formed
When the moon and sun are in line
The tide rising force is strongest
How are neap tides formed
When the moon and sun are perpendicular (90°)
Lowest tidal range
10-30% lower than average
What do tidal ranges determine
The upper and lower limits of erosion and deposition
The amount of time the littoral zone is exposed to sub aerial weathering
What are storm surges
When meteorological conditions give rise to strong winds producing higher water levels
What cause low pressure conditions in the North Sea
Depressions
Coastal sediment budget
The balance between the sediment being input and output of the coastal system
Low energy coast features
Wave energy is low
Deposition > erosion
Beaches and spits
High energy coasts features
Strong wave energy
Erosion > deposition
Headlands, cliffs, wave cut platforms
