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Oceanography > H11 > Flashcards

H11 Flashcards

1
Q

what has an effect on the coast line?

A
  1. wind
  2. waves
  3. tide
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2
Q

how do waves influence the coast line?

A

waves deliver energy that can change the form and structure of the coast line

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3
Q

what happens when a wave reaches the bottom? the ….

A
  1. speed decreases
  2. wave length decreased
  3. wave height increases
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4
Q

what can occur at uneven depths?

A

refraction (ombuiging)

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5
Q

what can occur with a large increase in wave height?

A

the wave can become unstable and break

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6
Q

currents along the coast have 2 components

A
  1. to the coast (onshore)

2. along the coast (longshore)

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7
Q

what happens when two longshore currents meet each other?

A

a rip-current (muistromen) can occur.

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8
Q

what also causes a rip current?

A

a combination of morphology and outgoing water

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9
Q

how to espace a riptide

A
  1. don’t panic
  2. don’t go against the current
  3. try to get the attention of beachgoers or the lifegaurd through calling and waving your arms
  4. swim diagonally right or left away from the current and swim back to shore as soon as the current decreases, so that you land on a sandbank where you can stand again.
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10
Q

sediment transport along the coast

A
  1. dependent on weather conditions and the strength of waves
  2. has an effect on the coastal profile
  3. often seasonally bound
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11
Q

sediment transport along the coast in the summer

A

in the summer, it is a swell profile. this is caused by a calm swell (deining). waves have little energy. sand piles up causing growth of the beach. characterised by a wide beach that is sloping steeply

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12
Q

sediment transport along the coast in the winter

A

in the winter, it is a storm profile. this is caused by a stormy rough sea with waves of high energy. sand is eroded which causes decrease in size of the beach. characterised by a small beach with a flatter descent. also characterised by bar migration: moving of sand banks

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13
Q

sand budget

A

supply - disposal sediment = sand budget

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14
Q

negative sand budget

A

decrease in coastal strip (kuststrook). it is problematic for safety, economy and ecology

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15
Q

neutral sand budget

A

conservation coast (upkeep –> instandhouding)

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16
Q

positive sand budged

A

increase in coastal strip (kuststrook)

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17
Q

how can sand budget be locally regulated?

A
  1. river input
  2. longshore drift
  3. undersea canyons (onderzeese kloven)
18
Q

what is optimal for the forming of dunes?

A
  1. enough sand
  2. enough wind
  3. large tidal wave (getijslag)
  4. beach with long and gradual expiration
19
Q

where are new dune formings found?

A

on seasides with onshore winds

20
Q

how do dunes migrate?

A

transport from windward (loefzijde) to leeward (lijzijde) called slumping. creates walking dunes!

21
Q

what plays an important role in the stabilisation of a dune?

A

vegetation

22
Q

dunes and coastal defence

A
  1. dunes form a natural part of coastal defence

2. dunes are still prone to erosion though so good management is essential

23
Q

barrier islands

A

barrier islands are islands built out of sediments and are often parallel to the coast; they are parted from the land through relatively shallow water. for example, the wadden eilanden

24
Q

what is needed to create a barrier island?

A
  1. large quantity of sediment

2. gradually sloping sea bottom in the direction of open water

25
Q

more theories of the forming of barrier islands

A
  1. isolation of ridges and banks through rising sea level
  2. separation of headlands (landtongen) through storms
  3. gradual rising of sand banks
26
Q

process of barrier island formation

A
  1. submergence of a coastal sand ridge
  2. segmentation of a land spit
  3. emergence of a longshore bar
27
Q

typical structure of a developed barrier island has:

A
  1. gradual slope nearshore zone
  2. dune row(s)
  3. hinterland (achterland)
  4. salt marshes
28
Q

barrier islands have the tendency to “walk”

A
  1. long term: through sea level rising

2. short term: through onshore and longshore currents

29
Q

erosion of the hard coast happens through:

A
  1. wave action
  2. pressure changes in cavities (holten) en cracks (scheuren)
  3. sediment against the coast
  4. loosening of some stones
30
Q

speed whereby cliffs are eroded is dependent on:

A
  1. composition of material
  2. weaker places
  3. amount of precipitation (neerslag)
  4. slope of the cliff
31
Q

process of cliff recession:

A
  1. runoff
  2. slumping
  3. mud flows
  4. ground water
  5. longshore drift
32
Q

what is the morphology of a rock coast after erosion?

A

wave-cut platform

33
Q

not only the base but also erosion effects higher up on…

A
  1. goats
  2. cows
  3. donkeys
34
Q

delta

A

an area where accumulation of sediment occurs by the mouth of a river.

35
Q

how is sediment deposited in a delta

A

deposition of sediment through decreasing current speed.

36
Q

what is a delta often part of?

A

a larger transition area… estuarium

37
Q

morphology of deltas on the basis of dominant factors:

A
  1. river
  2. waves
  3. tides
38
Q

river processes of deltas:

A

typical fanned out delta form (triangle)

39
Q

wave processes of deltas:

A

dispersion along the coast, coast is relatively skewed right

40
Q

tidal processes of deltas:

A

long sand banks and gullies (geulen) from the river mouth to the sea

41
Q

how do people attempt to stabilise the coast line?

A
  1. influence longshore currents
  2. redirect wave energy (against erosion)
  3. artificially strengthen coast line
42
Q

building with nature

A
  1. mussel and oyster farms as natural wave breaker
  2. sand marshes for lowering of wave energy against the coast
  3. recent example with huge human interference is marker wadden

Oceanography (13 decks)

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