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GEOG272 > Coastal Systems > Flashcards

Coastal Systems Flashcards

1
Q

Coastal landforms evolve in response to…

A

Sea level history
geology
climate
waves & tides

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2
Q

What are the 3 dominating factors of coasts?

A

Waves, Tides and Rivers

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3
Q

What are the 3 main divisions of the coastal area?

A

Foreshore
Backshore
Offshore

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4
Q

What is the foreshore?

A

Wet part of the coastline - not offshore

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5
Q

What is the backshore?

A

Usually dry - only wet under storm conditions

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6
Q

How is sediment carried in / through coastal areas?

A

-Orbital motion of water particles
-Breaking of waves
-Swash processes (rush of seawater on the beach after breaking of a wave)

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7
Q

What are the 3 general phases of nearshore bar evolution?

A

Generation and initial growth of bar
Migration or consolidation of bar
merging or erosion of bar

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8
Q

How has global sea level changed in modern times?

A

Risen 21-24cm since 1880s

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9
Q

What are the 2 components of sea-level rise?

A

Main: Input of water from greenland ice sheets
Secondary: Thermal expansion as ocean warms

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10
Q

Explain isostatic sea level changes?

A

Isostatic sea-level changes are local changes caused by subsidence or uplift of the
crust related either to changes in the amount of ice on the land, or to growth or
erosion of mountains.

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11
Q

What does the nearshore zone represent?

A

Where waves start to ‘feel’ or morphologically influence the bottom of the littoral zone.

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12
Q

What are the 3 types of nearshore currents

A

Longshore - dominant, often unidirectional current
Return Flow (undertow) - flow away from shore through gaps in intertidal bars.
Rip currents - short return (circulation cell)

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13
Q

What are the 3 types of breaking waves?

A

Spilling - gradual breaking over distance - flat terrain.
Plunging - crest curls over nearly vertical wall of water
Surging - base advances at same time as top, usually on steep beaches.

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14
Q

What is wave swash?

A

When water rushes up the beach. Limited by slope of beach

Maximum swash is the run-up level.

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15
Q

Provide an example of coastline evolution on very small time scale

A

formation of coastal bars (constantly moving hour to hour)

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16
Q

What deposition formation characterizes wave-dominated coastal landforms?

A

Spits - long narrow accumulation of sand with one end jointed to mainland and the other projecting out to sea or across an estuary

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17
Q

What is a barrier island?

A

Spit that has detached from the coast. Depositional coastal landform

18
Q

What are 3 factors that influence the formation of barrier islands and spits?

A

Constant flow of sediment
Wave energy
Direction of wave motion

19
Q

Name some characterizing factors of estuaries

A

-Somewhat enclosed
-Mixing of salt and freshwater
-Tidal

20
Q

How do salt marshes and mangroves protect from coastal erosion?

A

-Trap sediment
-Act as buffer

21
Q

What is the main factor controlling costal cliff erosion?

A

Rock hardness

22
Q

What are the critical processes involved in coastal cliff evolution?

A

-Mass movement
-Weathering
-Rock-removal processes (marine processes)

23
Q

How is climate change affecting high latitude coastal zones (in the arctic)?

A

-Arctic is warming 4x faster than the global base rate
-glacial retreat
-increased meltwater discharge
-increased landform erosion
-glacial ice, sea ice, permafrost & beach ice

24
Q

Which processes contribute to the formation of beach ridges?

A

Wave swash

25
Q

What is a beach ridge berm? What does it indicate?

A

Active ridge parallel to shoreline formed by swash processes
Indicates maximum sea-level run-up.

26
Q

How does a beach ridge plain form?

A

They are older sea berms. When a new berm forms and the beach ridge remains, then this will indicate the old sea level.

27
Q

What are the 2 ideas at the essence of integrated coastal zone management?

A

minimize disruption
maximize benefits

employ soft engineering (nature-based solutions)

28
Q

What are some examples of coastal geomorphological evolution at different chronological and spatial scales?

A

Smallest to largest:
sand ripples & runnels at the cm/m scale
sandbar m/100m
beach km
peninsula, coastal bar, spit etc
entire coastline

29
Q

Provide some examples of small-scale and large-scale geomorph. evolution in river systems

A
30
Q

Provide some examples of small-scale and large-scale geomorph. evolution in glacial systems

A
31
Q

What are the 4 processes affecting Coastal Morphodynamics?

A

Sea level history
Geology
Climate
Waves & Tides

32
Q

Explain the process of a wave as it moves from deep water to the shore (5 steps)

A

Shoaling
Breaking
Bores
Breaking
Swash

33
Q

The _____ is the maximum level the waves can reach on the beach

A

Run up level

34
Q

Wave _____ erodes and smooths coastlines

A

refraction

35
Q

explain the coastal classification triangle

A

Dominated by fluvial/wave/tide power/frequency/direction.

36
Q

Explain this picture

A

Spit formed by sediment deposit from fluvial forces when rounding the point from the stream. Reinforced by sediment deposit from ocean side and forced into triangular shape. Water slowing below transport velocity is caused by meeting of stream with ocean - opposing directions = slowing.

37
Q

Why do spits continuously curve inward?

A

Dependent on direction of longshore drift - recurved tip occurs by pushing sediment off the edge of the existing spit

38
Q

What is a common formation found in wave-dominated coastal landforms?

A

Barrier Islands

39
Q

What is a common formation found in tide-dominated coastal landforms?

A

Estuaries and wetlands/marshlands/mangroves

40
Q

Explain wtf going on here

A

Parallel lines on beach are beach riges - lowest one is the beach berm (formed by current swash processes). beach ridges are previous water levels/swash levels.

2 green lines are old fluvial streams worn down to the bedrock? green because of nutrient rich sediment?

GEOG272 (4 decks)

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