Coastal Systems Intro

Question 1

What are the four major factors controlling morphology along passive margin coasts?

Answer 1

1. Accommodation (sediment supply vs. sea level)
2. Tides
3. Waves
4. River present/absent

Question 2

Accommodation vs. Sediment Supply (describe the major process that allows a system to change)

Answer 2

• Transgression – when shoreline moves inland.
• Regression – when shoreline moves towards the water
• Prograde – coastline builds (deltas)

Question 3

How do rivers control the morphology? Draw a quick diagram.

Answer 3

In absence of strong waves/tides, rivers produce estuaries or subaerial deltas depending on their sediment discharge relative to sea-level rise.

Question 4

Wave and tide dominant energy systems

Answer 4

• In an absence of rives, waves and tides are the main systems that change the morphology of a shoreline.

Question 5

Funnel Shaped Embayment

Answer 5

consider the mouth of an estuary as a prism. As the water moves upriver, the prism becomes squished causing the water to fill inland. This is the reason the tide range is more drastic as it moves inland.

Question 6

What are the main types of estuaries?

Answer 6

Question 7

Draw the diagram and explain circulation within an estuary

Answer 7

Question 8

Draw the Salinity Profiles associated with circulation

Answer 8

Question 9

Estuary Turbidity Maximum (ETM)

Answer 9

Friction between the fresh water and salt water slows the freshwater down. This causes the freshwater to lose its competency and capacity the volume of sediment it can carry (and grain size). The sediment then falls out and causes it to concentrate where the fresh and salt water starts to mix.

Question 10

Tidal Asymmetry

Answer 10

Mouth of Estuary :

• Flood Tide Velocity = Ebb Tide Velocity
• Duration of Flood tide = Duration of Ebb tide

Estuary Funnel :

• Flood Tide Velocity > Ebb Tide Velocity
• Duration of flood tide < or = to duration of Ebb tide

Meander Zone:

• Really fast and short flood tide and really long slow ebb tide.

Question 11

Draw a diagram that shows the back and forth movement of sediment transfer by tides.

Answer 11

Question 12

Draw a “typical” estuary

Answer 12

Question 13

draw a wave-dominated estuary

Answer 13

• Waves are stronger than fluvial energy
• Waves tend to elongate the shoreline forming barrier islands (large sand deposits at the mouth)

Question 14

Tide Dominated Estuaries

Answer 14

• strong river dominance upstream
• But immediately have tidal influence
• Tidal sandbars have the form with the tides.

Question 15

Draw a diagram that shows the various types of depositional features.

Answer 15

Question 16

Distinguish the depositional features between transgressive and prograding.

Answer 16

Question 17

Draw the four major factors controlling morphology along passive margins

Answer 17