Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Geog 376 Topic 1 > Topic 2 > Flashcards

Topic 2 Flashcards

1
Q

where is soil forming processes dominant?

A

flat hilltops

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

with increasing ____, colluvial and mass wasting is dominant

A

gradient

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

colluvial footslope

A

where material accumulates and deposits

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

what happens if we had no rivers, regarding transport?

A

there would be no transport over longer distances. for example, on hill slopes, sediment is created and then transported down to rivers.

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

3 points on channel initiation (diffusive processes)

A
  1. Transport rate is proportional to hill slope
  2. Involve sediment movement without concentrated flow of water wind or ice
  3. Result in filling of depressions and smoothing of relief
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are two examples of channel initation?

A

Rainsplash and sheetwash

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

Rainsplash

A

raindrop impacts on bare soils cause disaggretion of soil, tiny craters and downslope sediment transport

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

Sheetwash

A

overland flow thats not concentrated in discrete channels, occurs when rainfall > infiltration capacity, can move loose material down gentle slopes. but can’t erode channels

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

Where are diffusive processes dominant ?

A

areas of shallow slope

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

Hortonian model

A
  • suggests there’s a critical point where from sheetwash (or Hortonian overland flow) starts eroding bed and initiates channel development.
  • moving downslope, volume of water flowing increases and the driving force increases until it can move sediment.
  • subparallel rills form downslope which become dominants and a first order stream forms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Channel Initiation (Advective Processes)

A

Material is moved with the fluid and in direction of fluid motion. Once water is focused into channels, networks evolve

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

Types of advective processes

A

Rills and gullies

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

Rills

A

sheetflows concentrate and cuts small parallel channels these may form and join to make a gully.

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

Gullies

A

deeper V shaped channels carved by concentrated run off

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

Hydraulic geochemistry

A

statistical relationships between the channel form/dimensions and Q

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

what is flooding?

A

flow that exceeds channel banks and occupies the floodplain

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

what are the two critical stages of flooding?

A

bankfull discharge and annual mean flood

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

megafloods

A

transport high amount of material but occur less frequently

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

low flows

A

incapable of transporting a lot of sediment

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

so what type of flow intensity allows for sediment transport?

A

moderate flows

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

effective discharge

A

discharge that transports the most sediments. this is due to the fact that it transports a moderate amount of sediment and occurs relative frequently

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

velocity deforms in 4 ways

A
  1. with distance from the bed
  2. Across the stream
  3. Downstream
  4. With time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

velocity increases towards ___ in a stream and decreases with ___

A

the centre, depth

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

turbulent

A

most common in nature. molecules fulfill random paths as they move downwards that provokes a lot of mixing.

25
laminar
not common in nature. water molecules flow along parallel path, little vertical variation, no mixing.
26
why does velocity vary in short time scales due to turbulence?
turbulence makes water flow in eddies more turbulence velocity leads to more velocity fluctuation
27
Reynolds number
compares driving (velocity, hydraulic) and resisting forces (viscous)
28
Froude number
compares inertial forces (velocity) and gravitational forces (weight of water)
29
total resistance has 3 main components
free surface resistance, channel resistance, boundary resistance
30
free surface resistnace
loss of energy due to surface waves & abrupt surface gradient changes
31
channel resistance
due to undulations in the channel beds and banks & changes in planform and cross section
32
boundary resistance
due to individual clasts or bed forms
33
___ elements all cause turbulence that resists flow
Resisting
34
relative roughness
ratio of water depth to particle size. so larger particles and shallower flow increases roughness
35
most of the energy in a stream is dissipated due to
flow resistance
36
stream competence
- maximum particle size that can be transported | - increases with velocity because competence is a function of boundary shear stress
37
stream capacity
theoretical maximum mass of sediment a stream is able to transport
38
stream load
amount of sediment actually carried
39
sediment transport processes will depend on the ____
river reach
40
3 flavours of sediment transport
solution, suspended load, bedload
41
solution
material that is dissolved. Travels at same velocity of fluid. Precipitates in lakes and oceans.
42
suspended load
fine-grained sediment transported in the water column and supported by turbulence. Travels a little slower than water. May stay suspended for longer distances without deposition.
43
Bedload
sediment transported along the bed by rolling and sliding (traction) and bouncing (saltation).
44
wash material
very small particles that once entrained stay in suspension and are not found in the bed. may form a large part of floodplain deposits.
45
bed material load
sediment that occurs in the bed (includes sediment that was transported as bedload and in suspension but deposited in the bed).
46
entrainment
initiation of grain moment balance of forces (gravity, drag, lift).
47
gravity
keeping the material at erst
48
drag
exerted by the flowing water
49
lift
velocity gradient above the particle creates pressure gradients
50
critical shear velocity (critical near bed velocity)
represents the relationship between velocity and entrainment. describes the entrainment "threshold"
51
critical shear stress
force responsible for entrainment and transport. the dragging force at the onset of particle motion tangential to the bed. signifies the down slope component of the fluid weight exerted as particle motion begins (a geomorphic threshold).
52
shields parameter
a dimensionless approach for determining critical shear stress. Divides critical shear stress by the submerged weight of the particle to be transported. Grain size diameter affects how much the particle will protrude up into the turbulent part of the flow.
53
True or False: If bed shear stress > critical shear stress, grains on the bed begin to move
True
54
critical stream power
Bagnold prosed that entrainment and transportation of bedload can be analyzed in terms of specific unit stream power.
55
what does the Rouse equation give us?
sediment concentration in the water column relative to a sediment concentration at the top of the bedload layer
56
how do we get suspended flux per unit width?
sediment transport rate can be predicted by multiplying concentration at any height by the velocity of the flow. Thus, to get suspended flux per unit width, we sum up vertically
57
where does deposition occur
under lower current velocities and shear stresses due to the time it takes particles to settle.
58
4 types of limitations of predictive models
spatial and temporal averages, turbulence neglected, measurement difficulty in natural streams, variable particle and bed characteristics
59
erodibility
tensile strength of the rock controls the erodibility of the rock

Geog 376 Topic 1 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions