Hydrosphere Flashcards

(64 cards)

1
Q

Explain the Albedo effect

A

Albedo describes the percentage of solar radiation that an object receives and is reflected away from the surface. Depending on the colour, this changes.
Darker = less reflection
Lighter = more reflection

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2
Q

How are coral reefs created?

A

Coral develops. It’s a marine animal. The exoskeletons of corals form coral reefs

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3
Q

What causes the sinking of Jakarta?

A

At Jakarta they decided to dig deeper for ground water. This caused land subsidence and simultaneously the city (and the world) is dealing with rising sea levels as well.

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4
Q

Why is sea level rise a problem?

A

Sea level rise itself is not a problem. The fact that people live in near-sea areas and contribute to it is a problem

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5
Q

What may be (negative) consequences of a small sea level rise?

A

People have to retreat -> coastal habitats farther inland
Destructive erosion -> floods can have a more devastating effect
Wetland flooding
Aquifer/agricultural soil contamination with salt (salinisation)
Lost habitat for fish, birds and plants

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6
Q

What is meant by transgression?

A

Ocean moves towards shore (result of sea level rise)

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7
Q

What is meant by regression?

A

Ocean moves away from shore (result of sea level fall)

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8
Q

What is progradation?

A

Shore and nearshore deposits move outward into the ocean and overlie deeper water deposits

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9
Q

What is retrogradation?

A

Deeper water deposits move towards land and overlie shallow water deposits

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10
Q

What is aggradation?

A

Sediments remain in the same general location and stack atop other similar sediments

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11
Q

Why are coastal zones relevant to humans?

A

2/3 of cities are in coastal zones
40% of the global population is within 100km of the coast

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12
Q

What are the human uses for coasts?

A

Trade
Fishery
Recreation
Nature
Farming
Temperate climates
Energy (wave, tidal, wind, fresh/salt water)
Land use (agriculture, industry, etc.)

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13
Q

What are the threats/risks at coasts?

A

Pollution
Storm surges/floods
Silting up (harbours)
Recreational pressure on ecosystems
Coastal erosion
Sea level rise

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14
Q

What are the five coast forming processes?

A

(Tidal) current
Wave action
Sea level changes
Coast composition (geological, tectonics, vegetation, erosion, sedimentation)
Climate

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15
Q

How are waves formed?

A

Wind blows over the water. Lower air layers experience more resistance since the water surface provides resistance. Energy from the wind is transferred to the water.

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16
Q

What happens when waves break?

A

As the waves approach the coast they decrease in speed. They then also decrease in wavelength (distance between two waves; one full cycle) and increase in waveheight. Back side of the wave rolls over the steep front.

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17
Q

How can the tidal flow lead to a storm surge?

A

Onshore winds
Low atmospheric pressure on the sea
Coastal morphology (water is pushed into a closed off area; no place to go but up)

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18
Q

What happened with the storm surge in ‘53?

A

There was a high tide.
There was low atmospheric pressure.
The water got pushed into a funnel at Zeeland: no place to go but up.

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19
Q

What types of coasts are there?

A

Cliffs
Lagoons
Fjords
Mangrove
Beach/dune system
Wadden shores
Estuaries
Saltmarshes
Wetlands
Deltas
Bayes and headlands
Coral coasts

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20
Q

What are the determinants of depositional coasts?

A

Fluvial power
Wave power
Tidal power

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21
Q

What are the five coastal types discussed during the lecture?

A

Estuary
Lagoon
Beach plain
Delta
Tidal flats and barrier system

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22
Q

What is an estuary?

A

Widened, funnel-shaped river mouth where fresh and salt water are mixed with noticeable tidal difference.

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23
Q

What is a lagoon?

A

A water surface between a barrier or beach shore. Can be connected to the sea.

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24
Q

What is a beach plain?

A

A wide band of sand along the coast whose surface consists of (semi) parallel beach walls alternating with shallow layers

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25
What is a delta?
System of river tributaries that flow into the sea
26
What is a tidal flats and barrier system?
Shallow sea with mud or sand flats with a noticeable tidal difference
27
What are examples of wave dominated coasts?
Tombolo (Gibraltar) Spit (near river outlet(s)) Bar/lagoon (spit growing across a bay)
28
What is longshore drift?
A process that concerns the transportation and sedimentation along a coast parallel to the shoreline and dependent on the angle of the incoming waves.
29
Where may the sediments come from?
Erosion of a cliff further up the current Longshore drift River sediments Sea floor/shore face
30
What is the "sand engine"?
The principle in which a big heap of sand is dropped on such a specific location so that the coastal drift distributes it further along the coast, preventing the need for repetitive beach nourishment
31
What are the two tide dominated coast types?
Tidal flats (Waddenzee) and estuaries (Eemsmonding, Westerschelde). Depending on the dominance of the river or sea.
32
What are the characteristics of the tide dominated coast type?
Low energy level Energy localised
33
What is a natural salt marsh?
The coastland bordering the tidal flats system
34
What does the tidal flats system consist of?
Outer delta Tidal inlet Tidal basin Wantij
35
What are characteristics of fluvial dominated coast types?
Supply of river sediment is larger than discharge due to limited - Tidal currents - Wave action Relatively fast flowing river Transport capacity decreases when entering stagnant water Sedimentation as a result
36
How can delta's be classified?
River dominated Wave dominated Tide dominated
37
What are the characteristics of fluvial dominated deltas?
Large drainage basin, outflow in energy poor environment (tides, waves) Fresh water flows over salt water "Bird foot" appearance (Example: Mississippi)
38
What are the characteristics of a wave dominated delta?
Wave action ensures strong mixing Sedimentation is fast process Higher supply than discharge; delta expansion (Example: Nile)
39
What are the characteristics of a tide dominated delta?
Storms or floods erode gullies Dendritic form Gullies slowly silt up Large foreshore of submarine sediments Sediments come from rivers, but tides create inlets/gullies
40
Small increase in sea level may lead to:
Coastal habitats further inland Destructive erosion Wetland flooding Aquifer.agricultural soil contamination with salt ('salinisation') Lost habitats for fish, birds, and plants
41
Higher sea levels may:
Cause more dangerous hurricanes (moving more slowly, dropping more rain) More powerful storm surges
42
Increased sea levels already:
Cause flooding of low-lying coastal areas forcing people to migrate Exposes millions to a risk of flooding
43
What is NAP and why is its concept relevant?
It means "Normaal Amsterdams Peil" and is a reference altitude used in the Netherlands. This concept is relevant because all around the world regions use a reference altitude according to their local circumstances
44
What is the last glacial maximum (LGM)?
The coldest period during the last ice age. During this period a lot of water was encapsulated in ice, not in the sea. Meaning a much lower sea level (120m lower)
45
What is the meltwater pulse?
Describes that how the sea level rises in jumps of large increases over a relatively short(er) period of time
46
What may be potential sources of meltwater pulses?
Melting of Antarctica. Melting of the Laurentide ice sheet (Canada)
47
Why are meltwater pulses relevant to us?
Because they may happen again. Melting of the Greenland ice sheet could potentially lead to a sea level increase by 3-6m
48
What is relative sea level change?
It concerncs the height of the ocean relative to the land at a certain location.
49
What is absolute sea level change?
It concerns the height of the ocean above the centre of the earth without regarding nearby land.
50
What is meant by eustatic controls on sea level?
Eustatic describes the change in total water volume It occurs globally It occurs quite immediately
51
What is meant by isostatic controls on sea level?
It describes the gravitational equilibrium between the lithosphere and the mantle Buoyancy determines the vertical/lateral adjustments in the (adjacent) lithosphere It occurs regionally It occurs with some delay
52
What is a well-known example of isostacy?
Glacial isostacy: Ice mass weight pushes up the earth crust surrounding it
53
What is the forebulge?
The part of the earth's crust that is pushed up due to a large, heavy mass pressing on another part of the crust nearby
54
Describe how sea level near the poles are rising due to the melting of land ice:
The weight of the land ice decreases -> force pushing up the land is decreasing -> land actually lowers a bit (more) -> causing relative sea level rise
55
What are causes of absolute sea level rise in the Netherlands?
Melting of land ice Expansion of sea water
56
What are cause of relative sea level rise in the Netherlands?
Tectonics in the Ardennes Isostatic rebound
57
What may be factors influencing the relative sea level rise in the Netherlands in the last 10,000y?
Influx of fresh water from the icecaps Thermal expansion of sea water (becoming warmer) The collapse of the forebulge Man-made: Land subsidence due to gas extraction Land subsidence due to salt extraction Land drying and sinking due to drainage (agriculture, canals, etc)
58
What is the one factor that counters the sea level rise in the NL?
Tectonic movement: but only with a few mm per century
59
How do we measure sea level rise?
Through the use of index points: - altitude (y) - age (x) - uncertainty
60
How can basal peat measurements be used as index points?
When sea level rises the groundwater level also rises. When groundwater reaches the surface, a swamp develops -> peat development. When finding these layers of peat, one can determine the height and the age -> index point
61
What are more modern ways of measuring sea level rise?
Tidal gauges Satellite measurements
62
What are the current global sea level drivers?
Thermal expansion (1,4mm/y) Glacier & ice cap melting - Small glaciers (0,6mm/y) - Greenland (0,5mm/y) - Antarctica (0,3mm/y) (Ground)water usage (0,09mm/y)
63
Which statements can be made about current global sea level rise and its cause?
The increase is virtually certain and it is accelerating (high confidence). Sum of glacier + ice sheet is the main contributor (very high confidence). Dominant cause of global mean sea level (gmsl) since 1970 is anthropogenic (man-made) (high confidence).
64
Does sea level rise acceleration also take place in the NL?
Yes, this has been concluded in a very recent study, one month ago.