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Flashcards in Chapter 16 Deck (60)
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1
Q

hydrologic cycle

A

movement of water through Earth’s four spheres

2
Q

inflitration

A

precipitation soaks into the ground

3
Q

runoff

A

precipitation runs over the surface

4
Q

transpiration

A

water absorbed by plants and later transferred to the atmosphere

5
Q

evapotranspiration

A

as evaporation and transpiration both move water from the surface to the atmosphere

6
Q

Runoff starts as

A

sheet flow which develops into tiny channels called rills which forms gullies which form streams

7
Q

streams

A

any water that flows in a channel, regardless of size

8
Q

river

A

carries a substantial amount of water and has many tributaries

9
Q

Drainage Basin

A

stream drains an area of land

10
Q

Divide

A

the imaginary line separating one basin from another; sometimes visible as high ridge mountain region

11
Q

3 zones of river systems

A

Sediment production, sediment transportation, sediment deposition

12
Q

Sediment production

A

zone of a river where more sediment is derived
Located in the headwater region of a river system
Generated by: broken bedrock, bank erosion

13
Q

Sediment transport

A

transported in trunk streams; amount of sediment being eroded equals amount being deposited

14
Q

Sediment deposition

A

when a river reaches a large body of water, the energy decreases and river deposits sediments; usually only fine sediments are deposited in oceans

15
Q

laminar flow

A

water flowing in a nearly straight path

16
Q

turbulent flow

A

water moving quickly in an erratic fashion

17
Q

Factors affecting flow velocity

A

the slope, channel shape, roughness, discharge,

18
Q

The slope, or gradient of a stream

A

steeper gradient has more gravitational energy to drive channel flow

19
Q

Channel shape

A

most effective channel has a small wetted perimeter (area where the rive is in contact with the channel) compared to its cross-sectional area

20
Q

Channel size and roughness

A

increase in channel size will increase the cross-sectional area to wetted perimeter ration thus increasing efficiency; rough channels create turbulence and decreased velocity

21
Q

Discharge

A

volume of water flowing past a certain point in a given unit of time
when discharge increases; the width, depth, flow, and velocity increase

22
Q

longitudinal profile

A

cross-sectional view of a stream

most have a concave shape

23
Q

head or headwater

A

source of the stream

24
Q

mouth

A

the downstream point where the stream empties into a larger body of water
discharge, channel size, and velocity increases towards the mouth

25
Q

Quarrying

A

involves removing large blocks from the channel bed

26
Q

abrasion

A

scraping, bumping, and rubbing

erodes and polishes sediment s

27
Q

Potholes

A

when fast moving, swirling sediment in eddies abrades a hole

28
Q

Corrosion

A

rocks gradually dissolving in flowing water can occur in limestone bedrock channels

29
Q

Transport of sediment by streams

A
Dissolved load (in solution)
Suspended load (in suspension)
Bed load (rolling along the bottom)
30
Q

Dissolved load

A

most of the dissolved load is brought to a stream via groundwater
NOT affect by stream velocity

31
Q

Suspended load

A

largest part of a stream is carried in suspension
amount carried is controlled by stream velocity and settling velocity (speed at which a particle falls through a liquid) of sediments

32
Q

Bed load

A

Coarse sands, gravel, and boulders move along the stream bed by saltation (skipping or jumping)
Less rapid and more localized than transport via suspended load

33
Q

Capacity

A

maximum load of solid particles a stream can carry

The greater the discharge the greater the capacity

34
Q

Competence

A

the maximum particle size a stream can transport

Streams with a faster velocity have a higher competence

35
Q

deposition of sediments by a stream

A

occurs when a stream’s velocity is less than the settling velocity

36
Q

sorting

A

particles of the same size are deposited at the same time in this process
Larger particles are settled out first

37
Q

alluvium

A

sediments deposited by streams

38
Q

Bedrock Channels

A

cut into the underlying strata

39
Q

meanders

A

streams transport suspended sediment in broad sweeping bends

40
Q

Cutbank

A

outside of a meander

zone of active erosion

41
Q

point bar

A

inside of a meander

zone of deposition

42
Q

cutoff oxbow lake

A

a meander that has been cut off from joined bends

43
Q

braided channel

A

is a network of converging and diverging channels that thread among numerous islands or gravel bars

44
Q

stream valley

A

channel and surrounding terrain that directs water to the stream
alluvial channels have wide valley floors
bedrock channels have V-shapped valleys

45
Q

base level

A

lowest point to which a stream can erode

46
Q

Ultimate base level

A

sea level

47
Q

Local or temporary base level

A

includes lakes, resistant layers of rock, and large rivers

48
Q

changing conditions causes readjustment of stream activities

A

raising base level= deposition

lowering base level= erosion

49
Q

graded stream

A

only transports sediment

50
Q

Deltas

A

when sediment-filled streams enter a large body of water

51
Q

water gap

A

notch where a river cuts through a ridge that lies in its path

52
Q

Antecedent stream

A

stream existed before the ridge was formed

53
Q

Superposed stream

A

Stream eroded into a preexisting structure

54
Q

headward erosion

A

stream that lengthen its coarse by extending the head of the valley upslope ; can result in stream piracy where the diversion of the drainage of one stream into another

55
Q

flood

A

occurs when the stream exceeds the capacity of its channel; most common and most destructive geological hazard

56
Q

Regional flood

A

seasonal flood that typically result from spring rains or rapid melting of snow

57
Q

Flash floods

A

occur with little or no warning in mountainous areas

58
Q

Ice-jam floods

A

ice forms in rivers creating dams that will break when temperatures rise

59
Q

Dam-Failure floods

A

Dams fail and release large amounts of water

60
Q

Flood Control

A

Artificial levees
Channelization
flood control dams
non-structural approach