1 - operation of coast as a system

Question 1

what is needed in a system?

Answer 1

INPUTS - energy and sediment
OUTPUTS - sediment removed by longshore drift deposited as landforms
TRANSFERS - erosion/transportation moves sediment
STORES - sediment deposited in landforms

Question 2

what kind of a system is the coast?

Answer 2

a dynamic open system - energy/sediment moves from system boundary into environment nearby

Question 3

what is the sediment budget?

Answer 3

balance between input and output

= input - output

Question 4

what are the major sediment suppliers in less resistant geology and low lying coastlines ?

Answer 4

less resistant geology = cliffs

low lying coastlines = fluvial sediment transported by rivers

Question 5

what is an AOELIAN input?

Answer 5

any sediment blown by wind

Question 6

what human influences change the sediment budget?

Answer 6

• hard engineering (groynes) = increases output of sediment

- soft engineering (beach nourishment) =. increases input of sediment

Question 7

how does sediment budget reach steady state equilibrium?

Answer 7

when inputs = outputs (equal/balanced)

if humans affect budget it is INBALANCED

Question 8

what is the effect of an imbalance?

Answer 8

if one system out of place can increase EROSION down coastline

Question 9

what are the inputs in the coastal sediment budget?

Answer 9

• from coastal stores
• from offshore
• cliffs
• rivers
• longshore drift in
• beach feeding
• dune building

Question 10

what are the transfers in the coastal sediment budget?

Answer 10

• NATURAL

- ANTHROPOGENIC (human)

Question 11

what are the outputs in the coastal sediment budget?

Answer 11

• to coastal stores (marshes/dunes)
• to offshore during storms
• estuarine sedimentation
• land claim
• dredging
• beach mining
• longshore drift out

Question 12

what property do all coastlines have?

Answer 12

stores of material and processes that operate as flows to move the stores

coastlines constantly changing because of erosion, transportation and deposition

Question 13

what are the inputs, outputs and transfers of beach and cliff sub systems?

Answer 13

BEACH:
—> inputs - subaerial processes
—> transfers - cliff collapse
—> outputs - transportation of sediment

CLIFF:
—> inputs - accumulation of sediment from longshore drift
—> transfers - transportation of sand by wind
—> outputs - removal of sediment by destructive waves

Question 14

what is a sediment cell

Answer 14

‘a length of coastline and its associated nearshore area within which the movement of coarse sediment is largely self contained’

both open and functional systems as movement exists across longshore drift divides

Question 15

where does coastal sediment come from

Answer 15

85% - river channels and estuaries (erosion)
5% - sea bed
5% - beaches
5% - cliff erosion

offshore bars and sandbanks act as sediment stores

Question 16

give 2 examples of sediment cells in the UK

Answer 16

Portland Bill -> Land’s End

Flamborough Head -> The Wash

Question 17

explain steady state equilibrium

Answer 17

variations in energy and morphological responses not deviating from long term average

cliff profile and beach gradient remaining fairly constant and equal marine and atmospheric energy received each year

Question 18

explain meta stable equilibrium

Answer 18

coastal system switches between 2 or more states of equilibrium, stimulated by trigger

hard engineering rapidly switching coastal system from one state to another

Question 19

what is dynamic equilibrium

Answer 19

balanced state of a system when its inputs and outputs are equal and sediment cells help achieve this

by feedback process, system adjusts to change and regains equilibrium

Question 20

what is positive and negative feedback

Answer 20

NEGATIVE - self regulation which restores equilibrium to a system

POSITIVE - an initial change in system amplified and causes further change