Coastal Systems Intro Flashcards
What are the four major factors controlling morphology along passive margin coasts?
- Accommodation (sediment supply vs. sea level)
- Tides
- Waves
- River present/absent
Accommodation vs. Sediment Supply (describe the major process that allows a system to change)
- Transgression – when shoreline moves inland.
- Regression – when shoreline moves towards the water
- Prograde – coastline builds (deltas)
How do rivers control the morphology? Draw a quick diagram.
In absence of strong waves/tides, rivers produce estuaries or subaerial deltas depending on their sediment discharge relative to sea-level rise.
Wave and tide dominant energy systems
- In an absence of rives, waves and tides are the main systems that change the morphology of a shoreline.
Funnel Shaped Embayment
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.
What are the main types of estuaries?
Draw the diagram and explain circulation within an estuary
Draw the Salinity Profiles associated with circulation
Estuary Turbidity Maximum (ETM)
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.
Tidal Asymmetry
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.
Draw a diagram that shows the back and forth movement of sediment transfer by tides.
Draw a “typical” estuary
draw a wave-dominated estuary
- Waves are stronger than fluvial energy
- Waves tend to elongate the shoreline forming barrier islands (large sand deposits at the mouth)
Tide Dominated Estuaries
- strong river dominance upstream
- But immediately have tidal influence
- Tidal sandbars have the form with the tides.
Draw a diagram that shows the various types of depositional features.
Distinguish the depositional features between transgressive and prograding.
Draw the four major factors controlling morphology along passive margins
