Brainscape's Knowledge GenomeTM

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


See full index

Geography - A - Global Systems > Block 3 (Temporal Variations In River Discharge) > Flashcards

Block 3 (Temporal Variations In River Discharge) Flashcards

You may prefer our related Brainscape-certified flashcards:
U.S. Geography flashcards World Geography flashcards
1
Q

Define river regime

A

Annual variations in a river’s discharge

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

Define river discharge

A

Volume of water moving down a river per unit of time

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

Define baseflow

A

The minimum river discharge - as water is regularly input to the channel via a steady stream of groundwater

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

Define stormflow

A

Additional discharge that enters the river channel after precipitation via overland flow and throughflow

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

What are the two categories of river regimes?

A
  • Simple regimes

- Complex regimes

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

Define a simple river regime

A

One high + one low discharge extreme per yr

Corresponding to seasonal changes in temp + precipitation

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

Define a complex river regime

A

Several extremes of discharge per yr

Often fed by many sources with diff climates

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

Give an example of a river with a simple regime

A

River Rhine, source in Switzerland + flows through Europe

  • Peak between May-August
  • Fed by temp rise + glacial melt in Summer months
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Give an example of a river with a complex regime

A

Colorado River, US

  • Multiple discharge peaks + lows
  • Fed from sources across 7 states, with different climates
  • E.g. summer melt of snow in Rockies causes peak + autumn conventional rainstorms over Colorado plateau cause peak
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Give an example of a river regime which is also influenced by human activity

A 
Colorado River (complex regime) 
- Humans issue control through Hoover Dam + Glen Canyon Dam
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the two categories of factors that influence river regimes?

A
  • Physical

- Human

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

What are the physical factors that influence river regimes?

A
  • Climate
  • Season
  • Geology
  • Vegetation
  • Drainage basin size + shape
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the human factors that influence river regimes?

A
  • Land use
  • Water use
  • Dams
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is widely accepted as the most important factor affecting river regimes?

A

Climate

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

How does climate affect river regimes?

A
  • Drives rates of precipitation (input)

- Drives rates of evaporation (output)

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

How does season affect river regimes?

A
  • Closely linked to climate (diff seasons have diff climates)
  • Impacts inputs: e.g. monsoon seasons, summer meltwater
  • Impacts outputs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does geology affect river regimes?

A
  • Affects lag time (rate at which water enters river), altering discharge at given time
  • If rock is permeable, porous, pervious water will percolate into rock, reducing overland flow, slowing lag time, reducing discharge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define permeability

A

Ability of water to pass through rock

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

Define porosity

A

Ability of rock to hold water inside it

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

Define perviosity

A

Ability of water to pass through faults/cracks in rock

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

How does vegetation affect river regimes?

A
  • Affects lag time, altering discharge at given time

- More vegetation, more interception, slower lag time, reduced discharge

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

How does drainage basin size + shape affect river regimes?

A
  • Larger basin catches more precipitation, increasing discharge
  • Steep-sided basin reduces lag time, increasing discharge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does land use affect river regimes?

A
  • Land use alters the physical aspects of the area, influencing discharge
    E.g. Urban area
  • Impermeable, non-porous, non-pervious rock
  • Lack of vegetation
  • High overland flow, short lag time, discharge peak after precipitation
24
Q

How does water use affect river regimes?

A
  • Water may be removed (industry, agriculture, domestic use)

- Alters discharge over time

25
Q

How do dams affect river regimes?

A
  • Give humans power to alter discharge at any given time

- Flow can be held back in reservoir or released into river downstream

26
Q

How do you calculate river discharge (cumecs - cubic m per sec)?

A

Cross sectional area (m) x velocity (m per sec)

27
Q

What are flood hydrographs?

A

Graphs to show how a river responds to a particular storm event/input of precipitation

28
Q

What is another name for storm hydrographs?

A

Flood hydrographs

Show how prone rivers are to flooding after certain amount of precipitation input

29
Q

What is plotted on the x axis of a storm hydrograph?

A

Time

30
Q

What is plotted on the y axis of a storm hydrograph?

A
  • Discharge (cumecs)

- Rainfall (mm)

31
Q

How is the rainfall data displayed on a storm hydrograph?

A

Bar chart

32
Q

How is the discharge data displayed on a storm hydrograph?

A

Line graph

33
Q

What is peak rainfall on a storm hydrograph?

A

Maximum rainfall (highest point on bar chart)

34
Q

What is peak discharge on a storm hydrograph?

A

Maximum discharge (highest point on line graph)

35
Q

What is lag time on a storm hydrograph?

A

Time interval between peak rainfall and peak discharge

36
Q

What is the rising limb on a storm hydrograph?

A

Part of line graph where discharge is increasing

37
Q

What is the falling limb on a storm hydrograph?

A

Part of line graph where discharge is decreasing

38
Q

What is baseflow on a storm hydrograph?

A

Normal, minimum river level (supplied by groundwater seeping into the channel) sometimes marked along the bottom of the discharge

39
Q

What is stormflow on a storm hydrograph?

A

Any additional precipitation to the baseflow that has enter the river during a storm event

40
Q

What is bankfull discharge?

A

Maximum discharge reached during an event before the river banks are overtopped and a flood occurs

41
Q

What is a flashy hydrograph?

A

Hydrograph with a short lag time, high peak discharge + steep rising/falling limb

  • Overwhelmed by lots of water reaching river fast
  • Prone to flooding
42
Q

What type of hydrograph means the area is prone to flooding?

A

‘Flashy’ hydrograph

43
Q

What are the two categories of factors that influence storm hydrographs?

A
  • Climatic factors

- River catchment characteristics

44
Q

What are the climatic factors that influence storm hydrographs?

A
  • Precipitation (type, amount, duration, intensity)
  • Antecedent conditions (weather + soil conditions pre-event)
  • Temperature
45
Q

How does precipitation influence storm hydrographs?

A

Intense or prolonged rain increases overland flow, causing a flashy hydrograph

46
Q

How do antecedent conditions influence storm hydrographs?

A

If weather has been warm + sunny, drying out the ground, then overland flow increases, causing a flashy hydrograph

If weather has been very rainy, water logging/saturating the ground, then overland flow increases, causing a flashy hydrograph

47
Q

How does temperature influence storm hydrographs?

A

If temp is low - less evaporation (+ maybe even frozen ground), increasing overland flow, causing flashy hydrograph

48
Q

How does river basin size influence storm hydrographs?

A

Smaller drainage basin - more concentrated - decreases lag time - flashy hydrograph

49
Q

How does river basin shape influence storm hydrographs?

A

Circular basins drain more quickly - flashy hydrograph

50
Q

How does the slope angle of land influence storm hydrographs?

A

Steeper slopes - reduce infiltration - increase speed of overland flow - flashy hydrograph

51
Q

How does drainage density influence storm hydrographs?

A

Rivers with more tributaries - more water to main channel - flashy hydrograph

52
Q

What does it mean to have a higher bifurcation ratio?

A

Lots of tributaries supplying the main river channel

53
Q

How does vegetation influence storm hydrographs?

A

Less vegetation - less interception - more overland flow - flashy hydrograph

54
Q

How does soil influence storm hydrographs?

A

Type: can lower infiltration capacity (e.g. clay soils) - flashy
Thickness: shallow can reduce infiltration - flashy

55
Q

How does geology influence storm hydrographs?

A

Impermeable, non-porous, non-pervious rock - less percolation - more overland flow - flashy

56
Q

How does land use influence storm hydrographs?

A

Urban: concrete + drains reduce lag time - flashy
Ploughed agriculture: less veg + compressed soil - flashy

Planted agriculture: increases interception - slow hydrograph
Dams + reservoirs: humans can control - steady hydrograph

57
Q

What case study is used for storm hydrographs?

A

Boscastle Floods (2004)

Geography - A - Global Systems (8 decks)

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