Water Measurement Guidebook TABLE of CONTENTS
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water measurement guidebook TABLE OF CONTENTS 1.0 Purpose of the Guidebook 1 2.0 Measurement Methods 2 2.1 Staff Gauge 5 2.2 Velocity-Area Method 7 2.3 Volumetric Method 11 2.4 Rain Gauge 13 2.5 Float Method 17 2.6 Head Rod Method 21 2.7 Weirs 25 2.8 Power Consumption Method 27 3.0 Glossary of Terms 29 4.0 References 29 List of Tables Table 1. Summary of water measurement methods 3 Table 2. Unit conversion 3 List of Figures Figure 1. Flowchart for selection of water measurement methods 2 Disclaimer The information provided in this document is intended as guidance only and is subject to revisions. This document is not a substitute for the law. Please consult the Water Act, the Water (Ministerial) Regulation and the specific authorization issued under the Water Act for all purposes of interpreting and applying the law. In the event that there is a difference between this document and the legislation or authorization, the legislation or authorization prevails. Alberta Environment is not responsible for any loss, damage or injury resulting from the reader’s use of or reliance on the information and methods contained in this document. ISBN: 978-0-7785-8535-0 March 2009 1.0 Purpose of the Guidebook Alberta Environment’s Water Use Reporting System allows licensees to report their water diversions online. Licensees enter the data on a daily, monthly or annual basis depending on the reporting requirement of their licence. Data collected can be entered online in the Water Use Reporting System (WURS) at: http://environment.alberta.ca/1286.html. If you do not have access to WURS please see contact information below. Water meters are the preferred method of measuring water diversion because of their simplicity and accuracy. However, if licensees are unable to acquire a water meter, the methods in this Guidebook, provide a consistent approach to measuring water diversions. The Guidebook will help licensees, improve the consistency and accuracy of their water diversion, as well as detect well and pump problems. The data obtained using this Guidebook will also help in the management of Alberta’s water resources and improve efficiency and conservation. Note to Users: Please note that the Guidebook outlines only direct methods to measure water diversions. Indirect methods, such as estimating water diversion based on livestock water requirements, are not provided. Contact Please dial toll-free 310-0000 and ask to speak with an Alberta Environment water specialist in your region. An electronic copy of this Guidebook is also available for download at http://environment.alberta.ca/1286.html Water Measurement Guidebook 1 2 Water Measurement Guidebook Figure 1. Flow Chart for selection of water measurement methods C. Volumetric Dugout/ Method C. Volumetric Reservoir Method Groundwater Pump C. Volumetric Method H. Power Water Source Consumption Pumping Method Station H. Power Consumption Method Pump Sprinkler/Pivot/ Wheel Move D. Rain Gauge Surface Water 2.0 Measurement methods A. Staff Gauge The following section provides Channel Flow Flood Irrigation information on the different types of No Pump B. Velocity-Area water diversion measurement methods. Method Surface Runoff Each method in Figure 1 has a Table 1 is a summary of key C. Volumetric corresponding worksheet with steps for considerations for the water use Method calculating the volume of water diverted. measurement methods described in The worksheets outline the requirements this Guidebook. For some types of E. Float Method necessary to do the measurements. Use diversions, more than one method is D. Rain Gauge the flow chart in Figure 1 to select a potentially applicable. In these cases, F. Head Rod measurement method based on the refer to Table 1 and the relevant sections diversion type and equipment available below for additional information to G. Weir to you. determine the most appropriate method. Table 1. Summary of Water Measurement Methods Measurement Construction/ Remote Data Method Accuracy Calibration Maintenance Installation Collection Possibility Remarks Yearly flow Simple to take measurement A. Staff Gauge Medium measurement at Minor Yes No but qualified person different levels required to calibrate B. Velocity-Area Training or help from Method High No No No No qualified person required C. Volumetric Medium No No Yes No Method D. Rain Gauge Medium No No Yes (Temporary) No E. Float Method Low No No No No F. Head Rod Low No No No No Simple to take measurement G. Weirs High Yearly Yes Yes Yes but qualified person required measurement to install and calibrate H. Power Every Consumption Low 2-3 years No No No Method Water Measurement Guidebook Table 2. Unit Conversion To Multiply By From To Multiply By From 0.028 Acre-foot US gallon 325,851 Cubic foot Cubic metre 7.481 Acre-foot Imperial gallon 271, 328 Cubic foot US gallon 6.229 Acre-foot Cubic feet 43, 560 Cubic foot Imperial gallon 2.471 Acre-foot Cubic decametre 1.233 Hectares Acre 3.281 Cubic metre US gallon 264.172 Metre Foot 25.4 Cubic metre Imperial gallon 219.969 Inch Millimetre 3,600 Cubic metre Litre 1,000 Hour Second 3 4 Water Measurement Guidebook Staff Gauge Staff 2.1 Staff Gauge The staff gauge method is used to measure flows in open canals and ditches. A staff gauge is a metal plate with accurately positioned markings. The metal plate is enamelled iron or steel, which is covered with a bake-on porcelain enamel finish to resist rust or discoloration. Typically, the markings are black numbers on a white background but different colours of enamel are also available. Water level readings can be taken directly off the gauge. The readings can be converted into a water flow rate (cubic metre per second) using a rating curve or a stage-discharge curve that must be developed by a qualified hydrometric technician. To determine the total quantity of water diverted, multiply the flow rate, from the rating curve, by the length of time it took to divert the water past the gauge. ➜ An electronic copy of this guidebook is also available for download at http://environment.alberta.ca/1286.html Water Measurement Guidebook 5 2.1 Staff Gauge Equipment Staff Gauge Staff 1. Installed staff gauge 2. Rating table (stage-discharge/storage relationship) If you do not have a staff gauge, choose another method for which you have the required equipment. Procedure 1. Read the water level in the canal from the staff gauge and record in column 1 2. Determine the flow rate corresponding to the water level from the rating table previously developed by the hydrometric technician and record in column 2 3. Record hours of operation/diversion in column 3 4. Multiply 2 and 3 by 3,600 to get total water diversion in cubic metres Observations and Computations Licence No.: Date: 1 2 3 4 Gauge reading Flow rate Hours of operation Total diversion (m) (m3/s) (hours) (m3) [=3,600 x 2 x 3 ] (enter this value online) Comments Unit Conversion From To Multiply By From To Multiply By Acre-foot US gallon 325,851 Cubic foot Cubic metre 0.028 Acre-foot Imperial gallon 271, 328 Cubic foot US gallon 7.481 Acre-foot Cubic feet 43, 560 Cubic foot Imperial gallon 6.229 Acre-foot Cubic decametre 1.233 Hectares Acre 2.471 Cubic metre US gallon 264.172 Metre Foot 3.281 Cubic metre Imperial gallon 219.969 Inch Millimetre 25.4 Cubic metre Litre 1,000 Hour Second 3,600 6 Water Measurement Guidebook 2.2 Velocity-Area Method Velocity-Area Velocity-Area Method Velocity-Area Method is most commonly used and relatively accurate method for discharge measurement in a stream or an open channel. However, proper training or help from technical person is required to use this method of measurement. In this method, the channel cross-section is divided into subsections and width and depth of water at each subsection are measured. 25-30 sections are recommended in a stream but fewer sections may be used in a small channel with smooth cross section and good velocity distribution. For accurate result space the subsections so that no subsection has more than 10 percent of the total discharge in it. A current meter is used to measure the velocity of flow by observing the number of revolutions and time at each subsection. The observations are usually made at 0.6 times depth of water if the depth of water is less than 75cm and or 0.2 and 0.8 times the depth of water from the water surface for a depth more than 75cm. A Pigmy Meter is used in place of Current Meter for shallow water with depth less than 45cm. The velocity of flow is determined based on observations and the current meter equation or rating table provided by the manufacturer. Discharge through each subsection is computed and the sum of these discharges is the total discharge passing through the cross-section at the time of measurement. The measurement may be carried out by wading, from cableway, bridge or using a boat depending on the local circumstances. Special attention and skill is required to use this method during ice condition. ➜ An electronic copy of this guidebook is also available for download at http://environment.alberta.ca/1286.html Water Measurement Guidebook 7 2.2 Velocity-Area Method Equipment 1. A Current Meter or Pigmy Meter 2. Wading rod 3. Measuring tape 4. Stop watch 5. Current Meter rating equation or table (provided by manufacturer) Method Procedure Velocity-Area Velocity-Area 1. Select a straight reach of river free of large boulder or any obstructions creating excessive turbulence, eddies or stagnant condition.