The BOREAS Information System

HYD-9 Stream Gauge Data


This stream gauge data was collected by the HYD-9 science team to support their research into meltwater supply to the soil during the spring melt period. This data was also collected for their research into the evolution of soil moisture, evaporation, and runoff from the end of the snowmelt period through freeze up.

Table of Contents

  1. Data Set Overview
  2. Investigator(s)
  3. Theory of Measurements
  4. Equipment
  5. Data Acquisition Methods
  6. Observations
  7. Data Description
  8. Data Organization
  9. Data Manipulations
  10. Errors
  11. Notes
  12. Application of the Data Set
  13. Future Modifications and Plans
  14. Software
  15. Data Access
  16. Output Products and Availability
  17. References
  18. Glossary of Terms
  19. List of Acronyms
  20. Document Information

1. Data Set Overview

1.1 Data Set Identification
Stream Discharge Rates Measured Hourly.

1.2 Data Set Introduction

1.3 Objective/Purpose
This project will seek to identify, through field measurements and computer modeling, the space-time distribution of meltwater supply to the soil during the spring melt period, and the evolution of soil moisture, evaporation, and runoff from the end of the snowmelt period through freeze up. The snow modeling activity will consist of two components: The first will make use of existing "off the-shelf" models, to forecast the onset and spatial extent of snowmelt and meltwater supply to the soil column prior to the 1994 IFCs. The second phase will extend, implement, and verify a physically based energy balance snowmelt model of the two sites and will evaluate approaches to aggregating detailed snowmelt predictions and measurements based on the model to larger scales, up to the size of a rectangle of several hundred km containing the northern and southern sites. The soil moisture modeling is based on a grouped response unit method which will allow characterization of soil moisture, evaporation, and runoff for the entire northern and southern sites.

1.4 Summary of Parameters
The following phenomena and their parameters are being reported in this data set:
Discharge Rate of Streams

1.5 Discussion
The locations for 12 tipping bucket measuring devices, 10 belfort gauges and 5 stream sites were selected within the two BOREAS study sites (NSA and SSA). These instruments were installed during the FFC-T (Focused Field Campaign-Thaw) 1994 in the last week of April 1994. They were in operation until October 1994 when they were removed from service. The gauges were reinstalled and collected data from April 1995 to October 1995. The tipping buckets and belfort gauges provided an approximate measure of the precipitation in the study areas. The discharge rates of streams provide a measurement of water leaving the study area. When used together these two sets of data provide a balance of the water cycle.

1.6 Related Data Sets
Precipitation data measured with belfort gauges and tipping buckets are also available.

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2. Investigator(s)

2.1 Investigator(s) Name and Title

Prof. Ric Soulis
University of Waterloo
Department of Civil Engineering
Waterloo, Ontario
N2L 3G1
Phone: (519) 885-1211  x2175
FAX:   (519) 888-6197

2.2 Title of Investigation
From Micro-Scale to Meso-Scale Snowmelt, Soil Moisture and Evapotranspiration from Distributed Hydrologic Models

2.3 Contact Information

Contact 1
Dr. Nicholas Kouwen
Univ. of Waterloo
Dept. of Civil Engineering
Waterloo, Ontario
N2L 3G1
Tel: (519) 885-1211 x3309
FAX: (519) 888-6197

Contact 2
Dr. Ric Soulis
Univ. of Waterloo
Dept. of Civil Engineering
Waterloo, Ontario
N2L 3G1
Tel: (519) 885-1211  x2175
FAX: (519) 888-6197

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3. Theory of Measurements

To continuously measure the discharge rate of a stream as a function of depth it is first necessary to construct a stage-discharge rating curve. To find the discharge rate at a specific stage, the cross section of the stream must be divided into subsections. No one sub-section should account for more than ten percent of the total stream flow. In the center of each subsection a current meter is lowered into the water at various depths to measure velocity. Two types of current meters were used in this study, a propeller meter, and an electromagnetic meter. A propeller meter measures the rate of flow by relating it to the rotation of its propeller while an electromagnetic meter measures the voltage produced when water passes through a magnetic field produced by the meter. Two different types of meters were used to reduce the error associated with each individual device.
When the velocities have been determined the total discharge of the stream can be calculated. This, along with the level of the stream at that time, can be used to compare the rate of flow at that time with other times. The discharge rate must be found at several different stream levels so that a relationship can be established between the height of the stream and its discharge. This relationship is represented graphically as a rating curve.
Once a rating curve is established the discharge can be found at any time if the height of the stream is known. To constantly monitor the stream height a float tube and a data logger were used. The stream height was manually checked at periodic times using a staff gauge. From this a detailed description of the stream's water level over several months was possible.

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4. Equipment

4.1 Sensor/Instrument Description

Propeller Meter
The Swoffer 2100 STDX current velocity meter consists of a propeller that rotates about an axis parallel to the flow of the stream. An onboard computer calculates the speed and displays it in the desired units. The computer averages the velocity over a given time (ie. 90 sec). The propeller meter was used to determine the rating curve for the stream.

Electromagnetic Meter
The MMI model 2000 flo-mate portable water flowmeter measures the velocity of a liquid using an electromagnetic method. When a fluid, which has conductive properties, passes through a magnetic field at a right angle, the magnetic field induces an electromotive force in the fluid at right angles to both the magnetic field and the velocity of the fluid. The voltage produced by the movement of the water through the meter is measured by electrodes and is proportional to the average velocity of the fluid. A built in computer uses this information to calculate and display the velocity. The electromagnetic meter was used to determine the rating curve for the stream.

Float Tube
A float tube consists of a hollow perforated plastic tube mounted perpendicular to the water's surface near the stream bank where it is accessible to observers. A float inside the tube reacts to different water heights that the data logger electronically records every 15 minutes. It is used to monitor the height of water over small intervals of time (ie. 15 minutes) for long periods of time.

Data Logger
The chart pac CP-X data logger was connected to the float tube so that it could record stream levels every 15 minutes. The data was stored in the logger's memory until it was retrieved.

4.1.1 Collection Environment

4.1.2 Source/Platform
Propeller Meter - mounted on a pole that was lowered manually into a stream.
Electromagnetic Meter - mounted on a pole that was lowered manually into a stream.
Float Tube - mounted in a stream near the bank where observers can reach it easily.
Data Logger - mounted inside the float tube

4.1.3 Source/Platform Mission Objectives
A measurement of the stream discharge rate was necessary so that a precise estimate of the total amount of water leaving the watershed due to surface and subsurface flows could be made. The data logger stored the information until it was retrieved.

4.1.4 Key Variables
Propeller Meter - Water Velocity
Electromagnetic Meter - Water Velocity
Float Tube - Stream Height
Data Logger - Voltage

4.1.5 Principles of Operation
A propeller meter and an electromagnetic meter are manually operated devices that measure the velocity of water. The propeller meter counts the number of propeller revolutions over a given time period. The computer compares this to a calibration coefficient and then displays the resulting velocity. The electromagnetic meter measures the voltage prvduced by water moving through a magnetic field, which is proportional the water's velocity. The float tube and the data logger are self-contained devices that automatically record the height of water every hour over an indefinite time period.

4.1.6 Sensor/Instrument Measurement Geometry
The propeller meter and the electromagnetic meter are mounted on a pole and lowered to various depths in a stream. The tester must repeat this for each subsection of the stream so that the average velocity can be calculated.
The float tube is mounted near the stream bank so that the tube is perpendicular to the surface of the water. The tube must be in an area that is accessible for data retrieval and can measure high and low water levels. The data logger is attached to the float tube.

4.1.7 Manufacturer of Sensor/Instrument

Propeller Meter - Swoffer Instruments Inc.
1048 Industry Drive
Seattle, Washington
98188 U.S.A.
(206) 575-0160
Fax (206) 575-1329

Electromagnetic Meter - Marsh-McBirney Inc.
4539 Metropolitan Court
Frederick, Maryland
21701, U.S.A.
(301) 874-5599
Fax (301) 874-2172

Float Tube -  Lakewood Systems
9258-34A Avenue
Edmonton, Alberta, Canada
T6E 5P4

Data Logger - Lakewood Systems
Edmonton, Alberta, Canada

4.2 Calibration
The propeller meter and the electromagnetic meter were calibrated by dragging them through a still body of water (a long tank, or a lake) at a known velocity and then adjusting the instrument as needed.
The float tube was calibrated by measuring the height of the water directly with a staff gauge and comparing that to the reading that the float gauge had determined.

4.2.1 Specifications
Propeller Meter
temperature range: -10 degrees Celsius to 49 degrees Celsius

Electromagnetic Meter
analog display: 0.1v per 1 m/sec
material: polyurethane shell
temperature range: 0 degree Celsius to 50 degrees Celsius

Float Tube
range: 0 to 4.6m (0 to 15 feet)
accuracy: +/- 1cm. (0.4 inches)
operating temperatures: -66 degrees Fahrenheit to 140 degrees Fahrenheit Tolerance
The propeller meter can measure velocities from 0.1 to 25 feet per second.
The electromagnetic meter can measure velocities from - 0.5 to 19.99 ft/sec (-0.15 to 6 m/sec). The meter measures the velocity to within 2% of the reading +/- 0.05 ft/sec.
The float tube can measure a stream heights from 0 to 4.6 meters.
The data logger can record voltage from 0 to 2.5 volts D.C. It can store 64 thousand samples with an accuracy of 1/4095.

4.2.2 Frequency of Calibration
The propeller meter and the electromagnetic meter were calibrated once before the readings were made and then once afterwards.
The float tube was calibrated during the beginning of the study period. The staff gauge readings were compared to that of the float tubes.

4.2.3 Other Calibration Information

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5. Data Acquisition Methods

Stream discharge measurements were made on 5 streams within the two study areas. Measurements were made on the stream to determine its rating curve so that stream height could be related to the rate of discharge. A float tube was set up to electronically monitor the height of the stream and record the information on a data logger. The data logger was connected to a notebook computer on site where the logger's stored information was transferred to the notebook. The data was then used with the rating curve to determine the rate of discharge every hour and checked for quality assurance.

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6. Observations

6.1 Data Notes

6.2 Field Notes
Several computer programs are required to develop the rating curves and the stream discharge rates.

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7. Data Description

7.1 Spatial Characteristics
The five stream sites were located so that they would give an overall view of water movement throughout the basin. In the large study areas (NSA and SSA), smaller basins were chosen so that a more detailed study could be performed. Two basins were chosen in the NSA and one in the SSA. In each basin the stream sites were chosen so that the flow contributions from a number of land cover types could be determined.
The stream sites were also chosen for other characteristics. They must be accessible during all water levels. The location must be suitable to measure the water height at high and low water levels. The river bed must be uniform in shape and of a material that resists erosion so that the rating curve will not change significantly over the period of observation. Areas that didn't overflow their banks and were away from human traffic were also desired.
The stream gauge at SW1 was chosen by HYD-9 Canada before the BOREAS project. During the project, the Environment Canada Water Survey operated the NW1 gauge.

7.1.1 Spatial Coverage
The five stream gauges measure the discharges throughout the 2 areas. The NSA basins were both 27 km^2 while the SSA basin was 574 km^2. Two additional stream gauges SW1 and NW1 were operated by the water survey.

The stream gauges were located at the following coordinates:

-------------------- ---------- ----------
NSA-NW1-HYD09-STGAN1  -98.49168   55.90877
NSA-NW2-HYD09-STGAN2  -98.52746   55.91528
NSA-NW3-HYD09-STGAN3  -98.37563   55.91683
SSA-SW1-HYD09-STGAS1 -104.61986   53.86453
SSA-SW2-HYD09-STGAS2 -104.68167     53.895
SSA-SW3-HYD09-STGAS3 -104.79116   55.92669
SSA-SW4-HYD09-STGAS4 -104.82028   53.92639

7.1.2 Spatial Coverage Map

7.1.3 Spatial Resolution
The stream discharge rates reported in this data set represent the discharge rate at a point in the stream in which they were located.
The collected data is designed to provide a reasonable estimate of the total surface and subsurface runoff from the White Gull Creek and Sapochi River watersheds during the study period.

7.1.4 Projection

7.1.5 Grid Description

7.2 Temporal Characteristics

7.2.1 Temporal Coverage
The data was collected from the end of April until October in 1994, 1995 and 1996. Gauges SW1 and NW1 were operated all year.

7.2.2 Temporal Coverage Map

7.2.3 Temporal Resolution
The data was collected at fifteen minute intervals over the study period. The data was then converted to hourly flow during the processing phase.

7.3 Data Characteristics

7.3.1 Parameter/Variable

7.3.2 Variable Description/Definition

7.3.3 Unit of Measurement

7.3.4 Data Source

7.3.5 Data Range
Observation Date: The date and time (GMT) when the measurement was made.
Discharge Rate: The discharge rate that the gauge measured. (cubic meters per

7.4 Sample Data Record

HYD09_STGA_NW002_26APR94       26-APR-94           .162 NW002 CPI     23-MAY-95


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8. Data Organization

8.1 Data Granularity
[BORIS and ORNL DAAC to fill in]

8.2 Data Format(s)
The CD-ROM data format consists of a text field to identify the data followed by several numeric fields to store the data for that day.

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9. Data Manipulations

9.1 Formulae
To find the average velocity in a subsection: Velocity = the average of the velocity measured at 0.8 of the depth and at 0.2 of the depth:
u = (u(0.8D)+u(0.2D))/2

To find the flow in a subsection:
Flow = Average velocity in subsection * area of subsection
Q = u * A

To find total discharge from velocity readings:
Flow = the sum of the flows in all of the subsections
Q = (sum from i=1 to i=N) of (u to the ith power) * A

To find the flow at a particular stream height:
Q = a2(volts-a1) + a3(volts-a1)^2 + a4(volts-a1)^3 + a5(volts-a1)^4 + a6(volts-a1)^5
where q = flow
a1 to a6 = coefficients of the rating
curve volts = the voltage recorded by the float tube for a specific height

To find the height of the stream from the data logger information:
height of stream = voltage output * calibration coefficient

9.1.1 Derivation Techniques and Algorithms
At frequent intervals during the monitoring period the flow of the stream (using the propeller and electromagnetic metering devices), the voltage produced by the float tube, and the true height of the stream measured from a staff gauge were recorded. This data showed a relationship between the level of the stream (staff and voltage gauges) and the rate of flow. The voltage produced by the float tube was converted to stream height using a calibration coefficient.
The information was entered into a computer program called 'Fitflow' that calculated the coefficients for the rating curve of a stream (a1 to a6). After this was done it was a simple matter to find the rate of flow using the equation.

9.2 Data Processing Sequence

9.2.1 Processing Steps

  1. set up necessary equipment
  2. measure the information necessary to develop rating curve.
  3. measure the stream height over the desired period of time
  4. perform the necessary data manipulations
  5. calculate the stream flow rates using the rating curve
  6. enter the flow rates into ASCII files with the appropriate identifying information noted beside each row (location, year, day, month)
  7. add the necessary column headings
  8. transfer the information to the database

9.2.2 Processing Changes

9.3 Calculations

9.3.1 Special Corrections/Adjustments

9.3.2 Calculated Variables

9.4 Graphs and Plots

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10. Errors

10.1 Sources of Error
Most error will occur in the actual measuring of the initial data. Turbulent water flow will effect the velocity readings by causing the meter to measure a larger or smaller velocity than actual. The stream site must be of uniform shape where the velocity measurements are taken to reduce variations in flow. If an instrument is allowed to get dirty it may become clogged and produce faulty readings. The propeller meter suffers from rotational friction that becomes more apparent at low velocities. Careful cleaning and calibration will prevent this though. As the temperature of water changes, its volume will also change.
Some of the gauges experienced shifting during the observation period. This movement made the development of rating curves more difficult.

10.2 Quality Assessment

10.2.1 Data Validation by Source
The electronic readings of the float gauge were routinely checked with the staff gauge readings taken directly from the stream. To account for the movement of the float tube, shifting of the streambed or the growth of vegetation, the rating curves were broken up into different time periods. For example there were different rating curves for the spring thaw than for the fall freezing period.
After the information had been collected it was run through an algorithm to detect any data that was abnormal, when compared to the rest of the data.

10.2.2 Confidence Level/Accuracy Judgement
The confidence level of the data varies with the particular stream and the level of the stream at the time of measurement.

10.2.3 Measurement Error for Parameters

10.2.4 Additional Quality Assessments

10.2.5 Data Verification by Data Center

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11. Notes

11.1 Limitations of the Data

11.2 Known Problems with the Data
For short periods of time some of the monitoring stations were inoperative. The data lost during this time made the final results less accurate.

11.3 Usage Guidance
The float tubes and data loggers were switched to double precision in May 1994. This effected the resolution of the reported data.

11.4 Other Relevant Information

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12. Application of the Data Set

The discharge rates of streams provide a measurement of water leaving the study area. When used together with precipitation data, these two sets of data provide a balance of the water cycle.

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13. Future Modifications and Plans

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14. Software

14.1 Software Description

14.2 Software Access

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15. Data Access

15.1 Contact Information

Primary contact:

Ms. Beth McCowan
BOREAS Information System
Bldg. 22, Room G87
Code 923
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771
(301) 286-4005
(301) 286-0239

15.2 Data Center Identification

BOREAS Project Office
Code 935, Goddard Space Center
Greenbelt, Maryland 20771

15.3 Procedures for Obtaining Data
Anyone wanting information may place requests by letter, telephone, FAX, electronic mail, or in person.

15.4 Data Center Status/Plans
As the BOREAS data are processed and sufficiently quality checked, they will be available from the EOSDIS ORNL DAAC (Earth Observing System Data and Information System) (Oak Ridge National Laboratory) (Distributed Active Archive Center). The BOREAS contact at ORNL is:

Merilyn Gentry, User Services/Data Coordinator
Oak Ridge National Laboratory DAAC
P.O. Box 2008
Bldg. 1507, MS-6407
Oak Ridge, TN   37830-6407
(615) 241-5926
(615) 574-4665

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16. Output Products and Availability

16.1 Tape Products
Contact BORIS Staff

16.2 Film Products
Contact BORIS Staff

16.3 Other Products
Contact BORIS Staff

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17. References

17.1 Platform/Sensor/Instrument/Data Processing Documentation

Hoskin Scientific Limited. 1992. Chart pac Cp-X (price and specification sheet).

Lakewood Systems Ltd.: float sensor fs-15: data sheet

Marsh-McBirney, Inc. Flo-Mate Model 2000 Portable Water Flowmeter Instruction Manual. 1990.

Swoffer Model 2100 Indicator Operation Manual

17.2 Journal Articles and Study Reports

17.3 Archive/DBMS Usage Documentation

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18. Glossary of Terms

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19. List of Acronyms

AES     - Atmospheric Environment Service of Canada
BOREAS  - BOReal Ecosystem-Atmosphere Study
BORIS   - BOREAS Information System
CD-ROM  - Compact Disk (optical), Read-Only Memory
DAAC    - Distributed Active Archive Center
EOS     - Earth Observing System
EOSDIS  - EOS Data and Information System
FFC-T   - Focused Field Campaign - Thaw
GMT     - Greenwich Mean Time
GSFC    - Goddard Space Flight Center
IFC     - Intense Field Campaign
NASA    - National Aeronautics and Space Administration
NSA     - Northern Study Area
ORNL    - Oak Ridge National Laboratory
SSA     - Southern Study Area
URL     - Uniform Resource Locator

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20. Document Information

20.1 Document Revision Date

20.2 Document Review Date(s)
BORIS Review:
Science Review:

20.3 Document ID

20.4 Citation
Ric Soulis, University of Waterloo
Nick Kouwen, University of Waterloo

20.5 Document Curator

20.6 Document URL

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Last Updated: July 22, 1997