running water (16) Flashcards

1
Q

What are the four spheres of the earth?

A

Hydrosphere
Atmosphere
Geosphere
Biosphere

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2
Q

Hydrologic cycle

A

The unending circulation of Earth’s water supply. The cycle is powered by energy from the Sun and is characterized by continuous exchange of water among the oceans, the atmosphere, and the continents

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3
Q

What is the distribution of total global water?

A

Oceans (96.5%)
Freshwater (2.5%)
Saline lakes and groundwater (1%)

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4
Q

What is the freshwater distribution?

A

Glaciers and ice sheets (68.6%)
Groundwater (30.1%)
Surface water and other freshwater (1.3%)

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5
Q

What is the surface water distribution?

A

Snow and ice (73.1%)
Lakes (20.1%)
Soil moisture (3.52%)
Swamps (2.53%)

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6
Q

Evaporation

A

The process by which liquid water changes into water vapor (gas)

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7
Q

Infiltration

A

The movement of surface water into rock or soil through cracks and pore spaces

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8
Q

Runoff

A

Water that flows over land rather than infiltrating into the ground

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9
Q

Transpiration

A

The release of water vapor to the atmosphere by plants

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10
Q

Evapotranspiration

A

The combined effect of evaporation and transpiration

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11
Q

Water balance

A

The volume that passes through each part of the cycle annually

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12
Q

What is the absolute quantity that is cycled through the atmosphere over a 1-year period?

A

380,000 cubic kilometers

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13
Q

Explain the idea that the hydrologic cycle is balanced.

A

Annual precipitation worldwide must equal the quantity of water evaporated

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14
Q

What is the most important force sculpting the Earth?

A

Water

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15
Q

What factors determine the amount of runoff?

A
The intensity and duration of rainfall
The amount of water already in the soil
The nature of the surface material
The slope of the land
The extent and type of vegetation
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16
Q

Why is runoff high in urban areas?

A

Many features are impermeable (buildings, roads, parking lots, etc.)

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17
Q

Sheet flow

A

Initial runoff flows in broad, thin sheets across slopes

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18
Q

Rills

A

Threads of current that form tiny channels

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19
Q

Gullies

A

Rills joined to form streams, and eventually, rivers

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20
Q

Stream

A

A general term to denote the flow of water within any natural channel. Thus, a small creek and a large river are both streams

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21
Q

River

A

A general term for a stream that carries a substantial amount of water and has numerous tributaries

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22
Q

What are the two sources that support streamflow in humid regions?

A

Overland flow that sporadically enters the stream and groundwater that enters the channel

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23
Q

How do streams lose water in arid regions?

A

The water table may be below the level of the stream channel. The stream loses water to the groundwater system by outflow percolating through the streambed

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24
Q

Drainage basin/watershed

A

The land area that contributes to a stream

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25
Q

Divide

A

An imaginary line that separates the drainage of two streams, often found along a ride

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26
Q

What river has the larges drainage basin in North America?

A

Mississippi River; 40% of the flow of the United States

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27
Q

What is the main source of fine particles (clays and fine sand) carried in stream channels?

A

Hillslope erosion

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28
Q

Headward erosion

A

The extension upslope of the head of a valley due to erosion

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29
Q

What causes downcutting?

A

Headward erosion

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30
Q

Three zones of a river system

A

Zones of sediment production (erosion)
Zone of sediment transport
Zone of sediment deposition

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31
Q

Zone of sediment production

A

Where most of the sediment is derived

Located in the headwaters

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32
Q

Zone of sediment transport

A

Trunk systems are how sediment travels

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33
Q

Zone of sediment deposition

A

Fine sediments and dissolved ions are typically the sediment that actually reaches the ocean

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34
Q

Dendritic pattern

A

A stream system that resembles the pattern of a branching tree

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35
Q

Radial pattern

A

A system of streams running in all directions, away from a central elevated structure, such as a volcano

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36
Q

Rectangular pattern

A

A drainage pattern characterized by numerous right angle bends that develops on jointed or fractured bedrock

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37
Q

Trellis pattern

A

A system of streams in which nearly parallel tributaries occupy valleys cut in folded strata

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38
Q

When does a dendritic pattern develop?

A

When the surface material is essentially uniform in its resistance to erosion (pattern is determined chiefly by the direction of slope of the land)

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39
Q

When does a radial pattern develop?

A

On isolated volcanic cones and domal uplifts

40
Q

When does a rectangular pattern develop?

A

When bedrock is crisscrossed by a series of joints and/or faults

41
Q

When does a trellis pattern develop?

A

In areas underlain by alternating bands of resistant and less-resistant rocks and is particularly well displayed in the folded Appalachian Mountains, where both weak and strong strata outcrop in nearly parallel belts

42
Q

Water gap

A

A pass through a ridge or mountain in which a stream flows

43
Q

Antecedent stream

A

A stream that continued to downcut and maintain its original course as an area along its course was uplifted by faulting or folding

44
Q

Superposed stream

A

A stream that cuts through a ridge lying across its path. The stream established its course on uniform layers at a higher level without regard to underlying structures and subsequently downcut

45
Q

Luminar flow

A

The movement of water particles in straight-line paths that are parallel to the channel. The water particles move downstream without mixing.

46
Q

Turbulent flow

A

Erratic movement of water often characterized by swirling, whirlpool-like eddies. Most streamflow is of this type

47
Q

How does turbulence contribute to a stream’s ability to erode its channel?

A

It acts to life sediment from the streamed

48
Q

Flow becomes more turbulent as the velocity of a stream _____.

A

Increases

49
Q

Gradient

A

The slope of a stream, generally expressed as the vertical drop over a fixed distance

50
Q

What happens when gradient is steeper?

A

More gravitational energy is available to drive channel flow

51
Q

Wetted perimeter

A

The total distance in a linear cross-section of a stream that is in contact with water

52
Q

What is the most efficient channel?

A

The one with the least wetted perimeter for its cross-sectional area

53
Q

Flow velocities are higher where?

A

In small channels

54
Q

Bankfull

A

When maximum flow velocity occurs, before water starts to inundate the floodplain

55
Q

What is the effect of rough channels on flow velocity?

A

Boulders, irregularities in channel bed, and woody debris significantly reduces flow velocity

56
Q

Discharge

A

The quantity of water in a stream that passes a given point in a period of time

57
Q

What is the discharge of the Mississippi River?

A

16,800 cubic meters

58
Q

Stage

A

The height of water surface relative to a fixed reference pint

59
Q

Longitudinal profile

A

A cross section of a stream channel along its descending course from the head to the mouth

60
Q

Mouth

A

The point downstream where a river empties into another stream or water body

61
Q

Quarrying

A

Removing loosened blocks from the bed of a channel during times of high flow rates

62
Q

Abrasion

A

The grinding and scraping of a rock surface by the friction and impact of rock particles carried by water, wind, and ice

63
Q

Potholes

A

A depression formed in a stream channel by the abrasive action of the water’s sediment load

64
Q

Corrosion

A

A process by which soluble rock is gradually dissolved by flowing water

65
Q

Dissolved load

A

The portion of a stream’s load that is carried in solution

66
Q

Suspended load

A

Fine sediment carried within the body of flowing water or air

67
Q

Bed load

A

Sediment moved along the bottom of a stream by moving water, or particles moved along the ground surface by wind

68
Q

What particles are typically carried in suspended loads?

A

Silt, sand, and clay particles

69
Q

Settling velocity

A

The speed at which a particle falls through a still fluid. The size, shape, and specific gravity of particles influence settling velocity

70
Q

Saltation

A

Transportation of sediment through a series of leaps or bounces

71
Q

Capacity

A

The total amount of sediment that a stream is able to transport

72
Q

What kind of capacity do large rivers with high flow velocities have?

A

High capacities

73
Q

Competence

A

A measure of the larges particle a stream can transport; a factor dependent on velocity

74
Q

The greatest erosion and transportation of sediment occurs during floods…

A

Increased velocity
Greater competence
More turbulence
Larger particles are set in motion

75
Q

Which particles settle first?

A

The largest

76
Q

Sorting

A

The degree of similarity in particle size in sediment or sedimentary rock

77
Q

Alluvium

A

Unconsolidated sediment deposited by a stream

78
Q

Bedrock channel

A

A channel in which a stream is cutting into solid rock. Such channels typically form in the headwaters or river systems where gradients are high

79
Q

Steps

A

Steep segments where bedrock is exposed (rapids, or waterfalls)

80
Q

Pools

A

Relatively flat segments where alluvium tends to accumulate

81
Q

Alluvial channel

A

A stream channel in which the bed and banks are composed largely of unconsolidated sediment (alluvium) that was previously deposited in the valley

82
Q

What are two common types of alluvial channels?

A

Meandering channels and braided channels

83
Q

Meander

A

A loop like bend in the course of a stream

84
Q

What are characteristics of meanders?

A

Streams that flow in relatively deep, smooth channels and primarily transport mud (silt and clay), sand, and occasionally fine gravel

85
Q

What is an example of a meander?

A

The lower Mississippi River

86
Q

Cut bank

A

The area of active erosion on the outside of a meaner

87
Q

Point bar

A

A crescent-shaped accumulation of sand and gravel deposited on the inside of a meander

88
Q

Cutoff

A

A short channel segment created when a river erodes through the narrow neck of land between meanders

89
Q

Oxbow lake

A

A curved lake that is created when a stream cuts off a meander

90
Q

Braided channel

A

A stream channel that is interwoven with other stream channels. Such channels form where a large portion of a stream’s sediment load consists of coarse material (sand and gravel) and the stream has a highly variable discharge

91
Q

Stream valley

A

The channel, valley floor, and sloping valley walls of a stream

92
Q

Slot canyons

A

In arid regions, where weathering is slow and rock is particularly resistant, narrow valleys develop with nearly vertical walls

93
Q

Base level

A

The level below which a stream cannot erode

94
Q

Ultimate base level

A

Sea level; the lowest level to which stream erosion could lower the land

95
Q

Local/Temporary base level

A

The level of a lake, resistant rock layer, or any other base level that stands above sea level