1c - Coastal sediment is supplied from a variety of sources

Question 1

Terrestrial, including Fluvial deposition, weathering and mass movement, marine erosion, aeolian deposition and longshore drift:

x8

Answer 1

• rivers are the main source of sediment input – sediment budget
• Sediment delivery to Shore is intermittent, floods
• In many places 80% of sediment is fluvial
• Weathering of cliffs inputs sed
• mass movements - cliff slumping - landfalls/slides
• sediment from wave erosion = marine sed
• Storm surge and rise in sea levels = increased cliff erosion = large rocks and boulders from collapse of undercut cliffs
• Longshore drift supplies sediment from One coastal area by moving it along the coast to adjacent areas

Question 2

Offshore – including marine deposition:

x3

Answer 2

• constructive waves bring sediment to the shore from offshore areas: marine deposition adding to the sediment budget
• Wind allows sediment to be brought from other locations forming sandbars, dunes, elsewhere on the beach
• This aeolian material is fine sand so the wind can move it easily

Question 3

Human – including beach nourishment:
x7

Answer 3

• when sediment budget is in deficit – beach nourishment can maintain the equilibrium
• Sediment brought by lorries and spread by bulldozers
• Sand and water can be pumped onshore by pipelines from offshore sources
• Low bunds holds mixture while water drains forming sediment
• Wind, waves, longshore drift remove sediment from budget
• beach management
• Sediment budget = sediment lost - sediment gained

Question 4

Affecting sig of sources of diff sediment:

Answer 4

• The weather can affect how strong the waves are and how much material can be deposited
• Seasons – in winter the waves are larger
• Geology – softer rock is more easily eroded
• Weathering – physical: freeze thaw, thermal expansion. Chemical: oxidization, solution
• Beach morphology
• Rising sea levels = more cliff erosion