Module 10 11 stream surveys
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Module 10/11 Stream Surveys. Stream Surveys – February 2004 Part 3 – Hydrologic Assessment. Objectives. Students will be able to: define velocity in a stream. identify methods used to determine velocity. define stream discharge. describe methods used to determine stream discharge.

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Module 10 11 stream surveys

Module 10/11Stream Surveys

Stream Surveys – February 2004

Part 3 – Hydrologic Assessment


Students will be able to:

  • define velocity in a stream.

  • identify methods used to determine velocity.

  • define stream discharge.

  • describe methods used to determine stream discharge.

  • explain the stage-discharge relationship.

Stream assessments
Stream assessments

  • Water quality

  • Habitat

  • Hydrologic

  • Biological

  • Watershed

Stream hydrology
Stream Hydrology

  • Velocity

  • Discharge (flow)

  • Stage-discharge relationship




  • The rate which the flow travels along the channel reach.

  • Measured in feet per second or meters per second

Velocity current meters
Velocity – Current Meters

  • Propeller type meters

  • Electromagnetic meters using waves to measure velocity

    • (e.g. March-McBirney).

Velocity in stream sensors

SonTek (YSI)

Velocity – in stream sensors

  • Useful for long-term velocity measurement in one place

  • Not for use in discharge determination

Bubbler flow sensor (Campbell Scientific)

Velocity determination float method
Velocity determination: Float Method

  • Inexpensive and simple

  • Measures surface velocity

  • Mean velocity obtained using a correction factor

  • Basic idea: measure the time that it takes an object to float a specified distance downstream

Stream discharge
Stream Discharge

  • The volume of water passing through the cross-sectional area of the channel per unit time

  • Average velocity of the water, in meters/sec, multiplied by the cross-sectional area of stream at that point, in square meters.

Stream discharge measurement setup
Stream Discharge Measurement: Setup

  • Stretch tape across river at right angle to direction of flow

  • Choose measurement intervals

    • 10 interval mininum

  • Width of the subsections can be variable across the cross-section.

  • No more than 10% of expected discharge per interval

  • No interval more than 3 meters wide

Stream discharge measurement setup1
Stream Discharge Measurement: Setup

  • At each point – measure velocity with meter at either 0.6 d or 0.2 and 0.8 d

  • Note: Point velocity is constantly changing (pulsation) – average over time

  • Operator position should NOT affect flow pattern near flow meter – downstream of meter, at arms length

Stage discharge relationship
Stage-Discharge Relationship

  • Discharge measurements are made at various stages to define the relation between stage and discharge

    • stage is the height of the water surface above an established datum plane.

  • Water-surface elevation called the "gage height"

Stage depth measurement devices

Ultrasonic depth sensor


Stage (Depth) Measurement Devices

  • Non-recording staff gage

  • Float sensors

  • Ultrasonic sensors

  • Pressure transducers

Pressure transducer

Staff gages (Forestry Suppliers)

Stage discharge relationship1
Stage-Discharge Relationship

  • Compute discharge at a range of stages

  • Plot depth vs flow and fit a curve

Stream surveys references
Stream surveys - references

  • Techniques of Water-Resources Investigations Reports


  • National Field Manual for the Collection of Water-Quality Data


  • Rapid bioassessment protocols for wadeable streams