Rapid Coastal Recession Flashcards
Explain how building coastal defences speeds up the rate of coastal recession.
Coastal defences built at 1 location will stop/limit the supply of sediment to a cell, meaning that another place down drift may not receive sediment for beach building. This means the beach will get narrower and less able to absorb wave energy, so that waves will hit the backshore with greater force.
Explain how offshore dredging speeds up the rate of coastal recession.
It removes sand/gravel from the offshore which reduces the supply of sediment to beaches, making them less able to absorb wave energy. It may also allow waves to maintain their circular motion and energy closer inshore, meaning they have a more destructive impact on the coast.
How do marine processes influence the rate of recession?
Wave type - destructive waves, high energy waves, prevailing winds, fetch, winter storms.
Tides - high tides may mean waves reach the backshore.
Submerging coastline - exposes cliffs to more erosion.
How does geology influence the rate of recession?
Geology - less resistant to erosion.
Lithology - jointed rock, rock with bedding layers.;
How do subaerial processes influence the rate of recession?
Weathering - cliffs that are susceptible to weathering speed up recession.
Mass movement - permeable strata over impermeable strata. Weaker cliffs speed up recession.
