1a)

Question 1

What are the inputs into a sediment cell?

Answer 1

• marine.
• atmospheric.
• terrestrial (River sediment, erosion and weathering, geology, human inputs (nourishment, pollution, building works, defences, recreation)).

Question 2

Processes in a sediment cell:

Answer 2

• Erosion
• deposition
• transportation (same as rivers)
• winds blowing material
• tides and rip currents moving material around

Question 3

What are the stores in a sediment cell?

Answer 3

The landforms (more will come in a later topic)

Question 4

What are the outputs from a sediment cell?

Answer 4

• Destructive waves
• Aeolian transport
• evaporation
• humans; i.e. taking sand away for glass

Question 5

Explain how a sediment cell can be viewed as a system: (8)

Answer 5

• Stretch of coastline defined by clear boundaries such as estuaries or headlands.
• Closed systems which means sediment does not enter or leave.
• Tend to stay in dynamic equilibrium - feedback (changes in flux of system) can occur but system self adjusts to equilibrium - negative feedback loops (movement of flux away from then back to equilibrium).
• Can also experience + feedback loops - (flux continues to move away from equilibrium), i.e. groynes causing sediment to continually collect at certain points of the beach - can become negative feedback loop if beach is appropriately nourished.
• Sediment cells consist of inputs (i.e. Aeolian transport blowing sediment into cell), processes (i.e erosion removing sediment from cliffs), outputs (i.e humans removing segment through dredging) and stores (i.e. spits storing sediment).

Question 6

How do the following disrupt a sediment cell?:

• Sea wall
• groynes
• damming
• dredging

Answer 6

Sea wall - prevents cliff eroding causing a promontory.

Groynes - prevent downward movement of sediment.

           - beaches depleted.
           - spits erode due to limited sediment supply.

Damming - less input from river.

Dredging - removes offshore bars and makes sand dunes prone to erosion.

Question 7

What did dredging do at Hallsands, Devon?

Answer 7

• extraction of around 395,000m^3 of shingle (1897-1902) to build naval dockyards in Plymouth
• led to 3m drop in beach levels
• NE gale in 1917 => waves = 12m+ in height => only 2 houses left in village as there was little beach left to protect the houses