Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Oceanography > Coastal water and estuaries - 10 > Flashcards

Coastal water and estuaries - 10 Flashcards

1
Q

What does it mean when waves ‘shoal’?

A

When waves touch the bottom of the floor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is wave set up?

A

A process whereby waves pile water against the short

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are longshore currents?

A

Currents generated by a pressure gradient (the sea surface slopes from areas of larger waves down to areas of smaller waves) that runs parallel to the shore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are rip tides?

A

A swift, narrow, sea ward flow perpendicular to the coastline generated by the convergence of longshore currents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What the angle of wave approach?

A

The acute angle between the wave crest and the beach (it’s rarely larger than 10º)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is sediment moved on the beach and the nearshore?

A

Currents and breakers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How can you divide the beach up?

A
  • Offshore

- Nearshore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is offshore?

A

The area seaward of where waves first being to break

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is nearshore?

A

The area from offshore to where waves wash back and forth across the beach … it can be divided into the breaker zone, the surf zone, the swash zone and the backshore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the breaker zone?

A

Where waves begin to break on the nearshore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the surf zone?

A

Where the waves expend most of their energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the swash zone?

A

Where waves wash back and forth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the back shore?

A

The land that adjoins the nearshore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Zones of the beach change with high and low tide. How?

A

At high tide, zones advance landward. At low tide, zones advance seaward

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a beach profile?

A

A cross section of a beach taken perpendicular to the shoreline that can be compared at different times to see if the beach is expanding or eroding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What 2 different types of beach profile exist?

A

A swell profile and a storm profile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the characteristics of a swell profile?

A
  • wide, broad berm
  • steep intertidal beach face
  • develops during the summer
  • enlarges the volume of the beach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the characteristics of a storm profile?

A
  • erosion of the berm
  • broad, flat intertidal beach face
  • develop during winter
  • coarse sediment left on the beach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the sand budget?

A

The balance between sediment added to and sediment eroded from the beach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where does beach sediment input come from?

A

River, sea-cliff erosion and onshore sediment transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is beach sediment removed?

A

Longshore currents, offshore transport and wind erosion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How are coastal cells formed?

A

When sand transported by long shore drift is permanently lost in submarine canyons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the best conditions for sand dune formation?

A
  • Abundant sand
  • Strong persistent onshore winds
  • Large tidal range
  • Beach is wide and gently sloping
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How far inland can sand dunes extend?

A

Up to 10km

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are blowouts?
Wind-scoured breaks in the dune or depressions in the dune ridge, commonly caused by destruction of vegetation
26
What is dune migration?
The movement of dunes. Sand salutes (bounces) up the windward side of the dune, collects in the wind-shadow and periodically slides down the leeward face of the dune
27
What impact does wave erosion have on sand dunes?
Creates a steep scarp at the base of the dune which then reflects wave energy, reducing erosion
28
What are barrier islands?
Landforms composed of sediment that parallel the coast and form where sand supply is abundant and a broad seafloor slopes gently seaward
29
What environments develop on barrier islands?
Nearshore zone, dune fields, back-island flats, forests and salt marshes
30
How are barrier islands created?
- Sand ridges on the coastal plain that become isolated due to sea level rise - Sand spits that become breached during a storm and remained separate by a tidal inlet - Vertical growth and emergence of longshore sand bars
31
What is rollover?
The migration of barrier islands landward due to sea level rise, which causes the washover of sediments from the seaward died to the landward side
32
How are sea cliffs eroded?
- Waves slam into cliffs ... water compressed inside cracks ... expands violently when the wave recedes ... shatters the rock - Sea water can dissolve some types of rock - Evaporation leaving behind salt crystals in faults ... chemically breaks down rocks
33
What does cliff recession depend on?
- Composition and durability of cliff material - Presence of joints, faults and cracks - Amount of precipitation - Steepness of the cliff - Wave energy
34
What is a wave-cut platform?
The gentle sloping area in front of the sea cliff that was produced by erosion and sea-cliff retreat
35
What is a delta?
An emergent accumulation of sediment deposited at the mouth of a river
36
What are the major areas of a delta?
- Delta plain - Delta front - Prodelta
37
What is the delta plain?
The flat, low-lying area at or below sea level that is drained by a system is distributaries
38
What is the delta front?
The shoreline and broad submerged area of the delta that slopes gently seaward
39
What is the pro delta?
The far offshore area of the inner shelf that receives fine sediment from the river
40
How can we divide up a delta?
- Topset bed - Forest bed - Bottomset bed
41
What are topset beds?
Flat-lying beds of sand and mud of the delta plain and deposited by the distributaries in their channels
42
What are foreset beds?
Thick silts and sands of the delta front that slope gently seaward and form the bulk of the delta
43
What are bottomset beds?
Flat-lying silts and clays of the pro delta that settle out of suspension far offshore
44
How does a delta expand?
Sediment accumulation (foreset beds bury bottomset beds and topset beds blanket foreset beds)
45
What is the shape of a delta dependent on?
The relative power of tides, waves and rivers
46
Where do river-dominated deltas form?
- Areas protected from large waves | - Small tidal range
47
What are the different types of delta?
- River dominated - Wave dominated - Tide dominated
48
What are wave dominated deltas altered by?
Wave erosion and longshore drift (most of the sediment if distributed along the coast and only a slight protrusion exists)
49
What are tide-dominated deltas altered by?
The ebb and flow of the tides into long, linear submarine ridges and islands
50
What are estuaries?
Semi-enclosed bodies of water where freshwater from the land mixes with sea water
51
How are estuaries created?
- Drowned river valleys (rise in sea level floods lower portions) - Fjords (glaciers retreat, sea level rises, lower portions flooded) - Bar built - Tectonic estuaries
52
What is the typical salinity gradient in an estuary?
Normal marine salinity at the tidal inlet to freshwater at he river mouth
53
What provides the energy for mixing of water in estuaries?
Tidal flow
54
How are estuaries categorised?
Based upon the relative importance of river inflow and tidal mixing
55
What are the three types of estuaries?
- Salt-wedge - Partially mixed - Well imxed
56
What is a salt wedge estuary?
An estuary dominated by the outflow from rivers (greater than inflow from tides)
57
What are the characteristics of a salt-wedge estuary?
- Well stratified - Sharp halocline - salt water form a wedge that lifts freshwater outflow off the bottom - internal waves propagate along the halocline - land-ward directed bottom current - sea ward directed surface current
58
What is sediment like in a salt wedge estuary?
River sand near the landward edge and river clays and silts elsewhere
59
What is a partially mixed estuary?
An estuary equally affected by river discharge and tidal mixing
60
What are the characteristics of a partially mixed estuary?
- Weaker halocline - strong landward directed bottom current due to upward mixing of seawater - beach and shelf sediment blanket the lower half of the estuary - river sand and mud blanket the upper landward half
61
What is flocculation?
When clay particles stick together in sea water forming a larger aggregate which sinks more rapidly
62
Where do mud shoals form?
Where currents are weak in the estuary
63
What is a well mixed estuary?
When tidal turbulence destroys the halocline, meaning water does not change with water depth
64
What effect does Coriolis have on wide estuaries?
Deflects river outflow to one side and tidal inflow to the other ... creates a lateral salinity gradient
65
What is sediment like in a well mixed estuary?
Abundant marine sediments that dominate throughout the estuary

Oceanography (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions