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GCSE - Geography (Dave) > Rivers > Flashcards

Rivers Flashcards

1
Q

What percent of the worlds water is found in seas and oceans?

A

97%

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2
Q

What is a drainage basin?

A

The area of land drained by a river

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3
Q

What is the catchment area?

A

The area within the drainage basin

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4
Q

What is the watershed?

A

The boundary between two or more drainage basins

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5
Q

Where are watersheds usually found?

A

The edge of highlands surrounding a drainage basin

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6
Q

What is a confluence?

A

The point at which two rivers or streams join together

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7
Q

What is a tributary?

A

A stream or smaller river which joins a larger river

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8
Q

Describe a cross section of the land near to the source of a river

A

V-shaped valley Narrow and shallow river

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9
Q

What is the name of the process that causes a river to erode downwards?

A

Vertical erosion

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10
Q

Name the four main forms of erosion

A

Hydraulic action Solution Attrition Abrasion

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11
Q

Explain hydraulic action

A

The force of the river causes air to be trapped in cracks of the bank. This pressure weakens the banks and slowly causes them to wear away

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12
Q

Explain abrasion

A

Erosion caused by the rubbing of materials carried by rivers

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13
Q

Explain attrition

A

Erosion caused when rocks and boulders transported by rivers and waves bump into each other and get smaller

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14
Q

What does attrition do to the size of the rocks?

A

Smaller Smoother Rounder

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15
Q

Name the four different transport processes in rivers

A

Solution Suspension Traction Saltation

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16
Q

Explain solution for erosion and transportation

A

Small pieces of rock and minerals are dissolved in the river and then carried along

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17
Q

Explain suspension

A

Fine, light materials are carried along the water

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18
Q

Explain saltation

A

Small pebbles and stones bounce along the river bed

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19
Q

Explain traction

A

Larger rocks and boulders are rolled along the river bed

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20
Q

What is required for traction to occur?

A

High energy level in the river

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21
Q

Where are energy levels usually at their highest in a river?

A

In the lower course

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22
Q

What causes deposition?

A

The river losing energy : Inside of a meander

Estuary

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23
Q

Where is deposition the most common?

A

Near to the mouth Shallow areas Low volume of water

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24
Q

Name the upper course features

A

-V shaped valleys -Interlocking Spurs -Rapids -Waterfalls -Gorges

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25
Q

Name the features of the middle course

A

-Wider, shallower valleys -Meanders -Oxbow lakes

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26
Q

Name the features of the lower course

A

-Wide, flat bottomed valleys -Floodplains -Levees -Deltas

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27
Q

Why do interlocking Spurs occur?

A

The river avoids areas of hard rock due to its low energy

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28
Q

How does a waterfall occur?

A

-A layer of hard rock above a thicker layer of soft rock causes the soft layer to erode faster -The soft rock slowly undercuts the hard rock due to it eroding faster and a steep edge is created -This overtime develops to be a waterfall as the height difference increases -Eventually the overhanging rock falls and the waterfall slowly retreats

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29
Q

How do Rapids form?

A

Ridges of hard rock cause an uneven slope. This creates Rapids

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30
Q

Why does water travel faster in the middle course compared to the upper course?

A

The channel has been widened and deepened and therefore less friction

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31
Q

Why do meanders form?

A

-The river erodes laterally -Deposition on inside -Erosion on outer side

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32
Q

What happens on the inside bend of a meander?

A

-The river flows slower -Material is deposited -More friction

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33
Q

What happens on the outside bend of a meander?

A

-Water erodes and undercuts the bank -Most energy -Less friction

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34
Q

What is the result of meanders being cut off?

A

An oxbow lake

35
Q

When is an oxbow lake most to form?

A

In times of flood

36
Q

What happens when oxbow starts to form?

A

-Sediment builds up, blocking it from the rest of the river -Over time the stagnant water could be replaced by land as sediment is deposited

37
Q

What is it called when a meander is replaced by land?

A

Meander scar

38
Q

What happens to interlocking Spurs if they occur in the middle course?

A

Bluffs (Truncated Spurs) are created

39
Q

What are created by floods in the middle course?

A

Levees

40
Q

What is the material which is deposited in the event of a flood?

A

Alluvium deposits

41
Q

What is precipitation?

A

Rainfall

42
Q

What is interception?

A

When trees and plants catch rainfall.

43
Q

What is infiltration?

A

When water on the surface enters the ground.

44
Q

What is percolation?

A

The gravity flow of water in soil.

45
Q

What is infiltration?

A

When water on the surface enters the ground.

46
Q

What is throughflow?

A

Sideways flow of water under ground.

47
Q

What is transpiration?

A

The flow of water up a plant and, eventually, its evaporation.

48
Q

What can cause flooding?

A

• A steep-sided channel • A lack of vegetation or woodland • A drainage basin, consisting of mainly impermeable rock • A drainage basin in an urban area • Heavy rainfall

49
Q

What can cause river erosion?

A

• Stream bed lowering• Saturation of banks• Redirection and acceleration of flow • Removal or disturbance of protective vegetation • Bank soil characteristics such as poor drainage or seams of readily erodible material within the bank profile• Wave action generated by wind or boat wash;• Excessive or inappropriate sand and gravel extraction• Intense rainfall events (e.g. cyclones).

50
Q

What are the advantages of living near a river or a delta?

A

• Fertile soil • Fishing • Tourism • Protection against hurricanes (only delta) • Sand and gravel for construction

51
Q

What are the two main ways river flooding can be managed?

A

Hard-engineering Soft-engineering

52
Q

What are some examples of hard engineering?

A

• Dams • River engineering

53
Q

What are some examples of soft engineering?

A

• Afforestation • Managed flooding • Planning

54
Q

What is the Bradshaw model?

A

A graphic representation of the change of characteristics as you go downstream

55
Q

What is the cross section?

A

A profile of the shape of the river channel

56
Q

What is the channel width?

A

The measuremeant from one bank to the other, either present flow or bankfull flow

Increases going downstream

57
Q

What is the mean depth?

A

Water’s surface to the river bed across the entire width

Increases going downstream

58
Q

What is the discharge of a river?

A

Volume of water which flows past a point in a given time.

Usually measured in cubic meters/second (cumecs) and increases going downstream

59
Q

What is the wetted perimeter?

A

The surface of the channel bottom and sides in direct contact with water

60
Q

What is the hydraulic radius?

A

Measure of a channel flow efficiency

cross-sectional area / wetted perimeter

Increases going downstream

61
Q

How does the channel bed roughness change as you go downstream?

A

Decreases: due to ersosional processes which increase due to a higher discharge

62
Q

How does turbulance and friction change as you go downstream?

A

Decreases: due to the smaller particle size

63
Q

What is evaporation?

A

When water particles heat up to a point where they become a gas

64
Q

What is the source?

A

The place where the river begins

65
Q

What is the mouth of a river?

A

Where the main river meets the sea/ocean/lake

66
Q

What is drainage denisty?

A

Total length of the rivers / area

67
Q

What type of rock underlys high drainage denisty?

A

Non-porous hard rocks such as clay

68
Q

What does high and low drainage density look like?

A
69
Q

What drainage density is more likely to flood?

A

High Drainage density

70
Q

What is groundwater flow?

A

Water flowing through rocks underground

71
Q

What is surface storage?

A

Water which is stored in rivers, lakes reservoirs etc.

72
Q

What is a rivers load?

A

The material which the river is carrying

73
Q

What is a meander scar?

A

The feature left behind when the water in an ox-bow lake dries up

74
Q

What are natural levees?

A

A raised river bank formed by deposition

75
Q

What are man-made levees?

A

Artificial raised banks to increase the channel capacity and reduce flood risk

76
Q

What is a floodplain?

A

An area of land around a river channel which is formed during times of flood when deposition occurs

77
Q

Why is alluvium useful?

A

Rich with minerals and is essential for fertile lands

78
Q

What is the bluff line?

A

Outer limits of the floodplain

79
Q

What is the strand line?

A

Outer limit of floodplain where material is left

80
Q

How is a delta formed?

A

A delta is formed when the river deposits its material faster than the sea can remove it

81
Q

Name and give an example of 3 types of deltas

A
  • Bird’s foot delta (Mississipi)
  • Arcuate delta (Nile)
  • Cuspate delta (Ebro)
82
Q

What is flocculation?

A

Salt from the sea causes the load from a river to join together and heavier so it is more likely to be deposited

83
Q

What are the disadvantages of living near/on a delta?

A
  • Risk of flood
  • Mosquitos (malaria, dengue)
  • Dirty and polluted water
  • Rising sea levels
  • Defences cost

GCSE - Geography (Dave) (16 decks)

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