Module 10/11 Stream Surveys Stream Surveys – February 2004 Part 3 – Hydrologic Assessment.
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Transcript of Module 10/11 Stream Surveys Stream Surveys – February 2004 Part 3 – Hydrologic Assessment.
Module 10/11Stream Surveys
Stream Surveys – February 2004
Part 3 – Hydrologic Assessment
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s2
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. explain the stage-discharge relationship.
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s3
Stream assessments
Water quality Habitat Hydrologic Biological Watershed
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s4
Hydrologic assessments
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s5
Stream Hydrology
Velocity Discharge (flow) Stage-discharge relationship
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s6
Velocity
USGS
The rate which the flow travels along the channel reach.
Measured in feet per second or meters per second
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s7
Velocity – Current Meters
Propeller type meters Electromagnetic meters using waves to measure
velocity (e.g. March-McBirney).
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s8
Velocity – in stream sensors
Useful for long-term velocity measurement in one place
Not for use in discharge determination
Bubbler flow sensor (Campbell Scientific)
SonTek (YSI)
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s9
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
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s10
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.
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s11
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
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s12
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
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s13
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"
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s14
Stage (Depth) Measurement Devices
Non-recording staff gage Float sensors Ultrasonic sensors Pressure transducers
Ultrasonic depth sensorNRRI
Pressure transducer
Staff gages (Forestry Suppliers)
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s15
Stage-Discharge Relationship
Compute discharge at a range of stages Plot depth vs flow and fit a curve
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s16
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s17
Importance of flow/discharge in determining loading
Slide to be completed by 3/31/04
Developed by: Richards, Reed, Ruzycki Updated: February 2004 U3-m10/11c-s18
Stream surveys - references
Techniques of Water-Resources Investigations Reports http://water.usgs.gov/pubs/twri/
National Field Manual for the Collection of Water-Quality Data http://water.usgs.gov/owq/FieldManual/
Rapid bioassessment protocols for wadeable streams http://www.epa.gov/owow/monitoring/rbp/