Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Geohazard > Flooding - Streams > Flashcards

Flooding - Streams Flashcards

1
Q

streams can be subdivided according to

A
  1. whether they are water-holding or not
  2. linear form of the river
  3. cross-profile or “transverse section” of the river
  4. length-profile or “longitudinal profile”
  5. genesis or evolution of the river
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

three types of streams

A

perennial, ephemeral, intermittent

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

A stream that has flowing water year-round during a typical year. The water table is located above the streambed for most of the year. Groundwater is the primary source of water for stream flow. Runoff from precipitation is a supplemental source of water for stream flow.

A

perennial

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

A stream that has flowing water during certain times of the year, when groundwater provides water for stream flow. During dry periods, this stream may not have flowing water. Runoff from precipitation is a supplemental source of water for stream flow.

A

intermittent

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

A stream that has flowing water only during or for a short duration after precipitation events in a typical year. In many states, this term refers to streambeds that are located above the water table yearround and streams where groundwater is not a source of water for the stream.

A

ephemeral

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

a smooth concave profile which is steep a the source and gentle at the mouth. It has no obstructions.

A

graded profile

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

The pattern of drainage which arises from and closely follows the trends of the underlying strata is called

A

concordant drainage

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

Those streams whose courses are the direct consequence of the initial topography

A

consequent streams

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

this stream flows in the same direction as that of the initial consequent stream, but which develops in response to a new base level formed due to inversion of relief.

A

resequent stream

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

are loose rock particles/sediments deposited on a stream

A

alluvium

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

what are the types of load?

A

bed load
suspended load
dissolved load

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

one of the key factors in a stream’s ability to erode the landscape is __________

A

velocity of water

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

what happens when water enters a meander bend?

A

it is forced to slow down on the inner part of the bend, but speeds up on the outer part

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

are unstable overhang located at the outer bank which is produced by the velocity increase on the outer bank and subsequently enhances the ability of the water to erode into the bank

A

cutbanks

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

accumulation of sediments on the inner bank due to slowing down of water

A

point bar

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

manifestations of active stream erosion

A

cutbanks
point bar

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

explain how stream channel migrates and become wider

A

when a stream erodes away one bank and deposits sediment along the opposite side.

as flowing water erodes cutbanks, it creates an unstable overhang which then will collapse (mass wasting.

the lateral migration of stream combined with mass wasting produces wider valleys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Grains are sorted by their size, density, and shape during erosion, transport, and deposition by traction currents.

A

hydraulic sorting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

t or f: downcutting by streams is performed by the stream itself

A

f (performed by sediments)

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

sediments in streams physically scrapes or wears away rock in a process called

A

abrasion

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

evidence for stream abrasion in solid rock can be seen in

A

potholes

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

how does potholes form?

A

during periods of high discharge when water column develops a swirling motion called an eddy current, causing sediments to rotate and grind holes into the rock

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

a circular current of water

A

eddy current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

the velocity of a particular stream is controlled by the _______ called ________; also referred to as ____

A

steepness of the channel ; stream gradient ; grade

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

is described as the change (loss) of elevation of the stream with distance downstream.

A

stream gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

the lowest level to which a stream can erode

A

base level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

this is often referred to as ultimate base level

A

sea level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

why is sea level considered as the ultimate base level?

A

because the ocean is the end or low point of most rivers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the lowest area that is below sea level?

A

Dead Sea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

these form when a streams ability to cut downward is reduced by a resistance rock body, lake, or inland sea

A

temporary base level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what possibly reduces a streams ability to incise thus forming temporary base levels?

A

resistance rock body, lake, or inland sea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

the ability of running water to transport and deposit sediment is dependent on _____________ and _________

A

water velocity ; type of particles being transported

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

describes the fraction of solid particles that is in a suspended state

A

suspended load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

t or f: suspended load moves at the same velocity with the water

A

t

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

this is what makes stream appear muddy

A

suspended load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

consists of sediment particles that roll, bounce, or remain stationary on streambed

A

bed load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

highly concentrated bedload layers that are developed beneath and driven by turbulent overlying flows

A

traction carpet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

the geologic process whereby a current transports larger, heavier rocks by rolling or sliding them along the bottom

A

traction

39
Q

a sediment transport process that moves grains across the bottom by bouncing or hopping.

A

saltation

40
Q

anytime a sediment is in motion, individual particles will undergo _____ causing it to become more ______ and more ______

A

abrasion; smaller; rounded

41
Q

t or f: smaller and rounded grains can be transported farther than angular grains

A

t

42
Q

the first particles to be removed from the bed load are the _____, ______, and ______-

A

smallest, least dense, and most angular

43
Q

the process whereby water separates sediment grains based on their size, shape, and density

A

hydraulic sorting

44
Q

hydraulic sorting sorts sediments base on:

A

size, shape, and density

45
Q

the combination of ________ and __________ produces relatively pure deposits of sand and clay

A

hydraulic sorting and chemical weathering

46
Q

this concentrates high-density particles thereby creating valuable ore deposits

A

hydraulic sorting

47
Q

what are examples high-density particles does hydraulic sorting concentrates?

A

gold, platinum, and titanium

48
Q

t or f: hydraulic sorting aids in creating placer deposits

A

t

49
Q

form when mechanical sorting causes concentration of heavy minerals of economic interest

A

fluvial placer deposits

50
Q

the first particles to return to bed load are the _____, _____, ______

A

largest ; most dense; most round

51
Q

hydraulic sorting leads to deposits called ____

A

bars

52
Q

bars located near the headwaters are often composed of ______ and ___

A

boulders and coarse gravel

53
Q

bars located in downstream areas are composed of________

A

sand-sized materials

54
Q

t or f: stream gradient in downstream areas is less steep

A

t

55
Q

crescent-shaped deposits found on the inside of meander bends

A

point bars

56
Q

are mound-shaped channel deposits consisting of sorted material ranging from boulders to coarse gravel to fine sand

A

bars

57
Q

crescent-shaped bars

A

point bars

58
Q

where does point bar develop?

A

inside the meander bends

59
Q

are formed when a river enters a lake or ocean and splits into smaller channels and begins to deposit sediment due to a decrease in velocity

A

delta

60
Q

what is the grading of deposition of sediment in a delta?

A

reverse (prograding)

61
Q

the weight from the continuous influx of sediment in deltas over time can cause the seafloor to sink and cause ______________

A

land subsidence

62
Q

a land subsidence allows deltas to become _______ and _________, thereby creating new land area

A

thicker and grow seaward

63
Q

where and how does a delta form?

A

deltas form at the mouth of a river where velocity decreases therefore, depositing sediments and creating small channels

64
Q

on what gulf does mississipi river feeds into?

A

gulf of mexico

65
Q

alluvium:streams ; ________:hillslopes

A

colluvium

66
Q

are large fan-shaped deposits that form where steep mountain streams empty out onto valley floors at the mouth of rivers

A

alluvium

67
Q

coalition of alluvial fans

A

bajada

68
Q

a channel that is choked with sediment is called a ______

A

braided streams

69
Q

streams also transport considerable amounts of dissolved ions (charged atoms) in what scientists refer to as ________

A

dissolved load

70
Q

how are alluvial fans formed?

A

abrupt changes in gradient and velocity causes sediment to deposit, choking the stream

overtime, the stream migrates across the entrance to the valley creating a fan-shaped deposit

71
Q

flat portion of the valley and the area that is first inundated during flooding

A

floodplain

72
Q

erosion on the outside of meander bend produces _______ over time, whereas deposition on the inner banks help build a flat plain on the valley floor called a _____________

A

wider valleys ; natural floodplain

73
Q

what is floodplain’s primary role?

A

periodically store large volumes of water moving through a drainage basin

74
Q

are pair of ridges that run parallel to the bank which are formed due to the deposition of sediment, commonly sand, at the edge of the bank

A

natural leeves

75
Q

are areas on the floodplain that are poorly drained and can remain wet long after a flood

A

back swamps

76
Q

are old floodplain left high and dry as river migrates

A

stream terraces

77
Q

t or f: back swamps are back portion of natural leeves

A

t

78
Q

well-defined stream terraces are often developed in response to

A

changes in base level due to:
1. sea level drop
2. tectonic uplift

79
Q

t or f: stream terraces are most likely inundated during a flood

A

F (less likely)

80
Q

in a __________ stream clay in in suspension while sand are on bed

A

low velocity

81
Q

in a __________ stream, both sand and clay are in suspension

A

high velocity

82
Q

t or f: natural leeves are often found along river channels that have well-defined floodplains

A

t

83
Q

t or f: flooding causes an abrupt decrease in velocity

A

t

84
Q

are developed where floodwaters are unable to return to the main channel

A

backs swamps

85
Q

how are natural leeves formed?

A

formed during flooding where abrupt decrease in velocity causes a deposition of sand-sized particles along the banks

86
Q

what are deposited on the floodplain during flooding?

A

finer particles of silt, clay, and organic matter

87
Q

as flow erodes the banks, it favors the development of a ______________ channel

A

meandering

88
Q

abandoned main channel, diverted because of flooding events

A

oxbow lake

89
Q

an emptied oxbow lake

A

meander scar

90
Q

explain how oxbow lakes are formed

A

A point bar grows into the river, making the meander more pronounced. As the meander expands, two adjacent concave banks grow closer to one another.

Eventually, continued erosion and high water events like floods or seasonal high water flows can join two concave banks together. The main river channel has changed its course, leaving the riverbend cut off from the main flow of the river.

91
Q

areas subjected to stream channel migration

A

meander belt

92
Q

the part of a valley bottom across which a stream shifts its channel from time to time especially in flood.

A

meander belt

93
Q

areas across which the river is prone to move

A

channel migration zone

94
Q

belt of meandering

A

meander “train”

Geohazard (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions