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Geography > Stream Erosion & River Systems > Flashcards

Stream Erosion & River Systems Flashcards

1
Q

What does fluvial mean (2)?

A
  • any stream-related processes

- any landform created or eroded by running water

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2
Q

What is the difference between streams and rivers?

A
  • river: a main stream

- stream: generic term

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3
Q

What is hydrology?

A

the science of water and its global circulation

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4
Q

What are the eight elements of stream formation?

A
  • sheetflow: surface water that is flowing downslope
  • interfluve: an area of higher land that separates two adjacent river valleys
  • rill: small-scale downhill-facing groove
  • gully: larger downhill-facing groove
  • confluence: the point at which two streams converge
  • drainage basin: the area from which a stream collects its water
  • drainage divide: the area between drainage basins
  • continental divide: drainage basins which divide the continent
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5
Q

Are there any drainage basins that do not empty into the ocean?

A

yes: the Great Basin

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6
Q

What is a drenditic drainage pattern (2)?

A
  • most common drainage pattern

- develops with rocks that resist erosion

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7
Q

What is a trellis drainage pattern (2)?

A
  • dipping/folded topography

- variety of rocks with different rates of erosion

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8
Q

What is a radial drainage pattern?

A

develops when streams flow off of a central peak

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9
Q

What is a parallel drainage pattern (2)?

A
  • associated with steep slope and high velocity streams

- more common in arid environments

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10
Q

What is a rectangular drainage pattern?

A

faulted/jointed landscape

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11
Q

What is a deranged drainage pattern?

A

glaciated landscapes

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12
Q

What are the three factors that create a fluvial landscape?

A
  • stream gradient: the rate at which the stream’s elevation from the headwaters to the mouth declines
  • base level: the level below which a stream cannot erode its valley
  • stream discharge: the volume of water flowing in the stream past a certain location at a certain time
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13
Q

In what three ways do streams erode?

A
  • headward erosion: headwaters erode upstream
  • downcutting: material eroded from bottom of stream
  • lateral erosion: side-to-side erosion
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14
Q

What is the difference between a graded and ungraded stream?

A
  • ungraded stream: stream is actively eroding/depositing material
  • graded stream: just enough energy to transport sediment; no erosion/depositon
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15
Q

What is the discharge formula?

A

Q = width x depth x velocity

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16
Q

What happens if stream discharge increases?

A

width, depth, and/or velocity increase

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17
Q

What are perennial streams (4)?

A
  • always flowing
  • more common in wetter environments
  • fed by groundwater and surface runoff
  • groundwater source allows stream to flow year-round
18
Q

What are intermittent streams (3)?

A
  • not always flowing
  • flows only with precipitation
  • mostly fed by surface runoff
19
Q

What are ephemeral streams (3)?

A
  • no water most of the time
  • flow in immediate aftermath of precipitation
  • fed by surface runoff only
20
Q

What are exoitc streams (3)?

A
  • stream that originates in wet environment and flows through dry environment
  • high potential for evapotranspiration
  • made worse by people diverting water for agriculture
21
Q

What is hydraulic action (2)?

A
  • water flowing through a stream channel squeezes and releases rocks
  • slowly loosens and lifts rocks
22
Q

What is abrasion (2)?

A
  • rock particles grind and carve out stream bed as they are transported
  • similar to sandpaper
23
Q

What is the difference between turbulent and laminar flow?

A
  • turbulent: water particles move randomly and cross paths in all directions
  • laminar: water particles flwoing in the same direction (calm appearance)
24
Q

What are the five factors of stream transportation?

A
  • stream gradient
  • rock type
  • climate
  • vegetation
  • human activity
25
Q

What is competence (2)?

A
  • the ability of a stream to move particles of a certain size
  • streams with higher velocity can transport larger particles; streams with lower velocity can transport smaller particles
26
Q

What is capacity (2)?

A
  • total amount of material that can be transported downstream
  • higher capacity and competence result in brownish color
27
Q

What are the three loads of stream transportation?

A
  • solution load: materials that have been dissolved into the water
  • suspended load: finer-grained material that remains suspended in the water
  • bedload: consists of saltation (particles bouncing along the bottom of the stream) and traction (particles dragged along the stream bed)
28
Q

What is aggradation (2)?

A
  • the buildup of a stream channel through the process of deposition
  • frequently occurs after flooding
29
Q

What is alluvium (2)?

A
  • any material deposited by running water

- generally deposited in floodplains, deltas, and stream beds

30
Q

What is a braided channel (2)?

A
  • deposition of alluvium in little islands in the stream

- typically in areas with glaciers

31
Q

What is a meander (5)?

A
  • stream moves laterally across valley floor
  • gradient, velocity, and sediment flow remain steady
  • point bar: experiences deposition
  • cutbank: experiences erosion
  • fast water on outside, slow water on inside
32
Q

What is an oxbow lake (4)?

A
  • a neck forms where a lengthening meander loops back on itself
  • over time, the neck narrows as erosion undercuts the banks
  • eventually, the stream erodes through the neck, forming a cutoff
  • an oxbow lake forms as sediment fills the area between the new stream channel and its old meander
33
Q

What is a nickpoint (3)?

A
  • the profile of the stream experiences an abrupt change in gradient
  • results in waterfalls and rapids
  • occurs with rock resistant to erosion, tectonic uplift, and temporary blockages
34
Q

What is a floodplain (3)?

A
  • byproduct of many years of alluvial deposits
  • higher land on either side
  • flood occasionally
35
Q

What are meander scars (2)?

A
  • byproduct of shifting channel

- remnant of old stream channel

36
Q

What is a backswamp (3)?

A
  • low-lying land off the main channel of the stream
  • water more likely to collect here
  • results in swampy/boggy area
37
Q

What is a yazoo stream?

A

tributary stream which runs parallel to main channel instead of joining it immediately

38
Q

What is a levee (3)?

A
  • earthen barrier on either side of a stream
  • can be natural or man-made
  • material is deposited on either side of stream after flooding
39
Q

What are alluvial fans (2)?

A
  • only form in dry environments

- ephemeral stream slows and expands after exiting canyon

40
Q

What are river deltas (2)?

A
  • form when stream exits confining channel

- rich soil, productive agriculture

Geography (11 decks)

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