Changing Rates of Recession Flashcards
Rates of recession are not constant
They
Wind direction/fetch
Tides
Seasons
Weather systems
Occurrence of storms
Wind direction and fetch
Wind direction at the coast varies and may change every day
The wind can be onshore or offshore
Rates of erosion (and so recession) are greater when winds are blowing onshore
In most areas, wind generally comes from one main direction - this is known as the prevailing wind direction
When prevailing wind direction is also the direction of the largest fetch this can lead to the build-up of large destructive waves causing rapid erosion
High tide occurs twice a day
Twice a month the Sun, Moon and Earth are in alignment increasing the gravitational pull; this causes the highest tide known as a
spring tide
Rates of recession are greatest during high tide because this is the time when the water and waves reach the backshore
The waves also have more energy when they reach the backshore leading to more erosion
Seasons
Rates of recession are likely to be greater in winter than in summer because
storm events that cause destructive waves are more common in winter months
Weather systems
The UK is located between warm tropical air and cold polar air
It experiences periods of both high pressure (anticyclones) and low pressure (depressions)
During anticyclones there are
during depressions
gentle winds and low waves, so rates of recession are low
the winds are much stronger, leading to high waves and greater rates of recession
Storms
Storms lead to high energy, destructive waves
These waves increase the rate of erosion and therefore, coastal recession
In Cornwall, over a two-week period, …………..cubic metres of cliff face was eroded along a 300-metre stretch of coastline, as a result of the 2013/14 storms
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