Human Actions & Coastal Recession Flashcards
Rapid coastal recession is caused by physical factors (geological and marine) but can also be influenced by human actions such as
dredging, dams or coastal management
These actions affect the processes within the coastal system including those in the sediment cell
Dredging
The removal of sediment from rivers or the sea
This impacts on the amount of sediment being deposited at the coast
Dams
The construction of dams, traps ………….. behind the dam wall
It is estimated ……………..billion tonnes of sediment is stored behind the world’s dams and this increases by a billion tonnes each year
Like dredging, this starves the coast of sediment
river sediment
100
It is estimated that dams on the river Ebro in Spain have led to a ………% reduction in sediment downstream
93%
The reduction of sediment supplied to the coast due to dams and dredging leads to greater coastal erosion because:
Beaches decrease in size as they are not being supplied with sediment
Destructive waves have more impact by increasing the rate of coastal erosion
Coastal management
Coastal management can impact on the rate of recession because it affects the rate of erosion
In some areas coastal defences such as in places like Hornsea sea walls and rip rap reduce the amount of erosion
This slows recession of the coast
In other areas coastal management affects the movement of sediment
Groynes at Hornsea on the Holderness coast reduce
longshore drift
Groynes at Hornsea on the Holderness coast reduce longshore drift which has a affect on where
This starves areas down the coast such as Mappleton of sediment also known as terminal groyne syndrome
As with dams and dredging the reduced supply of sediment decreases………….. and increases….
beach size and increases the impact of destructive waves