Unit 2 - Dynamic Shorelines Flashcards

1
Q

What are the six types of coastlines?

A

Permafrost coasts, Sandy beaches, Rocky beaches, Wetlands and marshes, Cliff-backed beaches, Estuaries

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2
Q

What is the most dynamic part of the beach?

A

surf zone

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3
Q

Where is the surf zone located?

A

extends from the breaker zone to the shore

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4
Q

When do waves break in the surf zone?

A

when water depth is ~1.5x wave height

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5
Q

How do waves in the surf zone break?

A

Can break as a spilling breaker on low gradient slopes, a plunging wave on moderate gradients, or a surging wave on steep slopes

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6
Q

What occurs during breaking?

A

waves transform potential energy to kinetic energy, manifesting as wave bore moving shoreward as broken white water

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7
Q

What can happen at the shoreline?

A

currents can be deflected alongshore and water may return seaward as a rip current

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8
Q

What does a rip current facilitate in terms of water movement?

A

drives transport between inner shelf and surf zone.

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9
Q

What causes a rip current?

A

Incoming waves push water toward shoreline, creating imbalance of water piling up in surf zone.

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10
Q

Where is a rip current typically the strongest?

A

break in sandbar where water seeks path of least resistance back through surf.

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11
Q

What happens to a rip current’s strength after passing through a narrow gap?

A

It begins to spread out, considerably weakening the velocity and strength of the rip current circulation.

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12
Q

What fish species do surf zones support?

A
  • large elasmobranchs that are of international conservation concern, such as white sharks
  • heavily harvested bony fishes, such as tailor.
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13
Q

What are fish assemblages in surf zones impacted by?

A
  • intense recreational fishing
  • commercial netting
  • coastal urbanization
  • beach modification
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14
Q

What effects does the environment have on surf zone ecosystems?

A

direct, but often hard to understand

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15
Q

What happens when broken waves reach the base of the wet beach?

A

they collapse and run up the beach face as swash in the swash zone

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16
Q

What are other important facts about swash?

A

Includes uprush and backwash, produces relatively steep seaward sloping swash zone (1 - 20°)

17
Q

What happens as sediment is deposited in the swash zone?

A
  • can build a berm
  • may also contain beach cusps, spaced ~ every 20 to 30 m
18
Q

What is a berm?

A

a near horizontal to slightly landward-dipping sand surface, the area where most people sit when they go to the beach

19
Q

How are beaches classified based on dynamics?

A

Wave dominated, Tide modified, Tide dominated, Beaches+Rock/Reef Flats

20
Q

What are some characteristics of dissipative beaches?

A

A high energy double bar with a 500 m wide surf zone and multiple lines of breakers.

21
Q

What is the average height of a wave in a longshore bar and trough?

A

1.5-2 m

22
Q

Where do longshore bar and trough waves break?

A

near continuous longshore bar located 100-150m seaward of beach

23
Q

What is the width and depth of longshore trough separating it from the beach?

A

50-100 m wide, 2-3 m deep

24
Q

What are the effects of storms on coastlines?

A

increased wave action and storm surge

25
Q

What processes, that typically occur over months/years in coastal zones, are amplified by storms?

A

Erosion, sediment transport, and deposition

26
Q

What is coastal erosion?

A

process by which local SLR, strong wave action, and coastal flooding wear down or carry away rocks, soils, and/or sands along the coast

27
Q

What is the impact of storm surge on coastline vulnerability?

A

temporarily raises still water level, leading to erosion.

28
Q

How does erosion affect the sand in the berm and dune during storms?

A

moves sand out to sea and into sand bars.

29
Q

What can a single major storm do to large dune fields?

A

A single major storm can destroy large dune fields.

30
Q

How do wave-modified and tide modified beaches differ?

A

In wave-modified, the surface gravity waves are the main source of energy, compared to tides. In tide modified, the energy from tides is more important than the surface waves.