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Environmental Engineering: Water Resource and Supply Engineering > Surface Hydrology 1: River Flow > Flashcards

Surface Hydrology 1: River Flow Flashcards

1
Q

What is hydrology concerned with?

A

The occurrence & circulation of the waters of the earth in all their natural physical modes of movement. It deals with atmospheric, surface and
sub-surface phenomena.

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2
Q

Where do we extract water from?

A
  • Lakes
  • Soil Watert
  • Rivers
  • Ice
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3
Q

What volume of water is stored in oceans?

A

1370 10^6km^3

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4
Q

How can river flows be a hazard to society?

A
  • Flood risk
  • Drought risk
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5
Q

Whats an example of an irrigation project?

A

The Olmos irrigation project

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6
Q

What are the two key societal needs related to water resources?

A
  1. Direct supply (household, irrigation, industry).
  2. Indirect supplies (hydropower).
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7
Q

What is river discharge?

A

River discharge is the flux of water through a cross-section of a river at a specific point.

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8
Q

What is river discharge measured in?

A

It is typically measured in cubic meters per second (m³/s). It can also be normalized by catchment area, leading to dimensions of mm/day.

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9
Q

What is a hydrograph?

A

A hydrograph is a plot of river discharge over time, showing the variation of river flow rates.

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10
Q

What kind of problem can rivers be categorised in?

A

1-dimensional

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11
Q

What sources do rivers integrate the combined effect of?

A
  • Spatial precipitation
  • Evaporation
  • Soil and ground water routing
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12
Q

What are measurements taken on for hydrographs?

A

Measured using gauging station

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13
Q

What are the common methods used to measure river discharge?

A
  1. Direct measurement of volume passing through a section (impractical in most cases).
  2. Velocity-area method: measuring the velocity across the river’s cross-section and multiplying by the area.
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14
Q

What is river hydrometry?

A

Science of measuring variables related to river flow

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15
Q

What is the formula for calculating river discharge using the velocity-area method?

A

Q = v × A, where v is the average velocity over the cross-section, and
A is the cross-sectional area

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16
Q

What are velocity meters?

A

Velocity meters, like the Valeport propeller meters measure river velocity

17
Q

What is an ADCP?

A

Acoustic Doppler Current Profilers (ADCP) are used for larger rivers to measure water velocity by using sound waves

18
Q

Why is it difficult to measure river flow using velocity alone, and what is a common alternative?

A

Measuring velocity is complex due to changes in river conditions. An alternative is to measure the river stage (water height) and convert this to discharge using a stage-discharge relationship

19
Q

What can used to determine depth of water?

A

Pressure transducer

20
Q

How can artificial controls like weirs and flumes help measure river discharge?

A

A weir or flume alters river flow, creating predictable flow conditions. This helps establish a reliable stage-discharge relationship, i.e., sub and super critical flows

21
Q

What do we ideally want in the relationship between stage and discharge relationship?

A

Well -defined

22
Q

What is the importance of separating stormflow from baseflow in hydrology?

A

Separating stormflow from baseflow helps understand the hydrological processes affecting a catchment. This is crucial for flood risk management, as stormflow contributes to peaks in river discharge.

23
Q

What factors effect stage-discharge relationship?

A
  • Vegetation cycles
  • Ice cover
  • Rising and falling limb of the hydrograph
24
Q

What formula can be calculated from the use of weirs and flumes for discharge?

A

Q = KbH^(1.5)

25
Q

What re some flow indicators?

A
  • Maximum flow
  • MInimum flow
  • Mean flow
  • 10th percentile
  • 90th percentile
26
Q

What can flow measurements be described as?

A

Instantaneous

27
Q

What isa river flow measurement?

A

Momentary recording of the state of the river

28
Q

How do you calculate storm flow?

A

Total flow- base flow

29
Q

What can lead to peak discharge?

A
  • heavy rainfall
  • snow melt
  • rainfall on frozen or saturated
30
Q

What are some temp dependant regimes?

A
  • Glacial
  • Mountain snow melt
  • Plain snow melt
31
Q

Flow records across what time span are required?

A

20 - 30 year

32
Q

What is the start of storm flow called?

A
  • Inflexion point
33
Q

How to find of end of storm flow?

A

precipitation_end + (NxTL)

34
Q

What is the lag time?

A

Peak storm flow - peak precipitation

Environmental Engineering: Water Resource and Supply Engineering (3 decks)

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