Agricul 
 
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 MEASURING 
 
 IRRIGATION 
 
 WATER 
 
 VERNE 
 
 H. 
 
 SCOTT 
 
 
 
 CLYDE 
 
 E. HOUSTON 
 
 
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 easuring irrigation water is important as local and regional water 
 shortages become more widespread, and efficient water manage- 
 ment on the farm becomes a must. 
 
 ccurate water measurement of irrigation water is necessary to 
 assure proper distribution of surface supplies according to rights, 
 shares, or quantities ordered, and to maintain efficient perform- 
 ance of wells and pumps. 
 
 pplying the proper amounts of water helps 
 produce maximum growth yields; 
 prevent poor growth because of insufficient water; 
 reduce drainage problems because of too much water. 
 
 THIS CIRCULAR describes some of the most common devices and methods of measur- 
 ing water. It contains drawings, tables, and charts to help you quickly determine rate 
 of flow. It lists some advantages and limitations, but it is impossible to mention all that 
 may apply to any given situation. In fabricating, installing, operating, and maintaining 
 water-measuring devices, follow recommended procedures, or gross errors in measure- 
 ment may result. The illustrations show the general types of equipment, and are not 
 construction drawings. For design details and the hydraulics of measuring devices, con- 
 sult a textbook on hydraulics. 
 
 The Authors: 
 
 Verne H. Scott is Associate Professor of Irrigation and Associate Irrigation Engineer in the Agri 
 cultural Experiment Station, Davis. Clyde E. Houston is Irrigation and Drainage Engineer, Agricul- 
 tural Extension Service, Davis. Drawings by Jay Ryon. 
 
 This circular is a shortened revision of the University of California Bulletin 588, by J. E. 
 Christiansen, first published in 1935. 
 
 JANUARY, 1959 
 
Measuring 
 Irrigation Water 
 
 Verne H. Scott 
 
 Clyde E. Houston 
 
 Methods of Measuring Water 
 
 Methods of measuring water can be 
 grouped into three categories : 
 
 Direct methods (pages 3 to 4). 
 
 Velocity-area methods (pages 5 to 12) . 
 
 Methods employing a formed constric- 
 tion in the cross section of the ditch or 
 pipeline (pages 13 to 19). 
 
 Direct Methods 
 
 Using a container 
 
 Collecting water in a container of 
 known volume for a measured period 
 of time. This method can be used to de- 
 termine the rate of flow of small streams 
 such as irrigation furrows. To measure 
 
 the volume you may use a one- or five- 
 gallon bucket. Noting the time needed to 
 fill it to the top will give you the rate of 
 flow. 
 
 Measuring the change in 
 the water level 
 of a reservoir 
 
 A direct measurement of the flow rate 
 into or out of a reservoir can be made 
 by measuring the change in the water 
 level for a given period of time, provid- 
 ing the dimensions of the reservoir are 
 known. You will obtain reliable results if 
 the reservoir is lined to prevent seepage 
 loss; otherwise you must estimate the 
 seepage. 
 
 Collecting a known volume of water in a measured interval of time is a useful method of 
 determining flow rate of small streams such as irrigation furrows. 
 
 [3] 
 
.' 
 
 V 
 
 Direct volumetric measurement 
 
 Several types of water meters operat- 
 ing on this principle are shown on this 
 page. The first is a disk-type commercial 
 meter frequently used with small-diam- 
 eter pipe to measure volume of water to 
 urban residences. This type of meter 
 normally totalizes the volume of flow on 
 a register mounted on top of the meter. 
 The other three are commercial water 
 meters utilizing a propeller; they are 
 available for installation in pipe lines or 
 vertical riser pipes. Usually the propeller 
 is slightly smaller than the inside pipe 
 diameter, thus assuring a constant cross- 
 sectional area. A register on top of the 
 meter indicates the total volume of water 
 that has passed through the meter, or an 
 indicator can be supplied on some models 
 to show instantaneous rates of flow. With 
 this type of meter, watch out that no 
 debris is deposited on the propeller. 
 
 Tilt bucket 
 
 A tilt bucket consists of a balanced, 
 two-compartment, sectioned tank. When 
 one compartment fills to a known vol- 
 ume, the tank tilts, causing the filled com- 
 partment to empty while the other side is 
 brought into position to fill. A counting 
 mechanism totalizes the number of tilts, 
 and permits calculation of the total vol- 
 ume of water passing through the tilt 
 bucket. This type of measuring device 
 requires a situation where the water can 
 be delivered at sufficient elevation above 
 the bucket to permit the tilting. 
 
 Four types of water meters using direct 
 volumetric measurements: From top to bottom: 
 1. Disk-type residential meter, useful in small- 
 diameter pipe. 2. Propeller-type irrigation 
 meter at pipe outlet. 3. Propeller-type irriga- 
 tion meter within pipeline. 4. Propeller-type 
 irrigation meter for vertical riser pipe. The last 
 three are commercial types. 
 
Velocity-Area Methods 
 
 The rate of flow passing a point in a 
 pipe, ditch or open channel is deter- 
 mined by multiplying the cross sectional 
 area of water at right angles to the flow- 
 ing water by the average velocity of the 
 water. Normally you can determine the 
 cross sectional area by direct measure- 
 ment. But watch out for irregularities in 
 the bottom and sides of the channel. 
 
 Determination of the velocity is more 
 difficult, since in most ditches and canals 
 the velocity differs considerably at vari- 
 ous points within the cross section. 
 
 Always use the same units for the cross 
 sectional area and the velocity when mul- 
 tiplying them to obtain the rate of flow. 
 For example, if the cross sectional area 
 is determined in square feet and multi- 
 plied by the average velocity in feet per 
 second, the rate of flow will be cubic feet 
 per second. 
 
 Float method 
 
 The float method gives you an approxi- 
 mate measure of the rate of flow. It is 
 useful when more costly installations are 
 not warranted or high accuracy is not 
 required. 
 
 Select a straight section of ditch with 
 fairly uniform cross-sections. The length 
 
 Two-way tilt bucket may be used where water 
 drops from some height to permit tilting. 
 
 of the section (about 50 or 100 feet) will 
 depend on the current. Make several 
 measurements of depth and width within 
 the trial section, to arrive at the average 
 cross section area. Stretch a string or 
 tape across each end of the section at 
 right angles to the direction of flow. Place 
 a small float in the ditch, a few feet up- 
 stream from the upper end of the trial 
 section. Record the time the float needs 
 to pass from the upper to the lower sec- 
 tion. Make several trials to get the aver- 
 age time of travel. 
 
 To calculate the velocity in units of 
 feet per second, divide the length of the 
 
 Float method for determining rate of flow is inexpensive though not too accurate. 
 
 [5] 
 
Current meters are accurate, usable in ditch or channel. Two meters are popular in California: 
 Price current meter (left) and Hoff current meter (right). 
 
 section (in feet) by the time (in seconds) 
 required for the float to travel that dis- 
 tance. Since the velocity of the float on 
 the surface of the water will be greater 
 than the average velocity of the stream, 
 it is necessary to correct the measure- 
 ment by multiplying by a coefficient — 
 usually .80. 
 
 To obtain rate of flow, multiply this 
 average velocity (measured velocity x co- 
 efficient) by the average cross sectional 
 area. 
 
 Among small objects which make good 
 floats are a long-necked bottle partly 
 filled with water and capped, a block of 
 wood, an orange or a lemon. 
 
 Current meter method 
 
 A current meter accurately determines 
 the velocity in a ditch or channel. It is a 
 small instrument containing a revolving 
 wheel or vane that is turned by the move- 
 ment of the water. Of the types available, 
 the two most common in California are 
 the Price meter and the Hoff meter. (See 
 drawings above.) 
 
 The Price current meter contains an 
 impeller which consists of six conical- 
 shaped cups mounted on a vertical axis. 
 When the meter is immersed in moving 
 water, the impeller revolves, and the time 
 for a given number of revolutions is de- 
 termined by the operator. The comple- 
 
 tion of every revolution or every fifth 
 revolution is indicated by an electrical 
 sounding device connected to earphones 
 which the operator wears. 
 
 The Hoff meter contains a rubber im- 
 peller mounted on a horizontal axis. Its 
 chief advantage is that it is less affected 
 by eddies, or turbulence. It has been used 
 for measuring the velocity of water flow- 
 ing from the end of the discharge pipe of 
 pumping plants. 
 
 Current meters are either mounted on 
 a rod, or suspended on the end of a cable 
 above a heavy weight. Use rod mount- 
 ings in measuring shallow streams that 
 can be waded. For deep streams or for 
 measurements from a bridge or cableway 
 some distance above the water surface, 
 use the cable suspension. 
 
 Before being used in the field, current 
 meters are rated or calibrated to deter- 
 mine the relation between the speed of 
 rotation of the impeller and the velocity 
 of the water. From this rating a graph 
 or table is prepared showing the velocity 
 for a given number of revolutions in a 
 given time interval. 
 
 Current-meter measurements are gen- 
 erally made by trained hydrographers or 
 by engineers familiar with this work. 
 These persons are continuously carrying 
 on research to develop newer methods 
 and more accurate procedures. 
 
 [6 
 
Here are a few facts useful to know 
 for anyone : 
 
 The channel at the measuring section 
 should be straight, with a fairly regular 
 cross section. When possible, avoid struc- 
 tures with piers in the channel. Several 
 measuring points are laid off across the 
 stream at right angles to the direction of 
 flow. These are generally spaced an equal 
 distance apart, not more than the mean 
 depth of the channel nor more than 10 
 per cent of its width, making a total of 
 not less than 10 measurements. On wide 
 streams an interval of 10 feet is ordi- 
 narily used. The depth and mean velocity 
 of the stream are then determined at each 
 measuring point. 
 
 Four methods are generally acceptable 
 for determining the mean velocity with 
 a current meter: multiple-point, two- 
 point, single-point, and vertical integra- 
 tion. 
 
 The multiple-point, being the most 
 accurate, is the method by which the 
 accuracy of other methods is generally 
 checked. At each measuring point the 
 velocity is determined at several closely 
 spaced points from the bottom of the 
 channel to the water surface. If these are 
 equally spaced, the mean velocity in the 
 vertical approximates the average of the 
 measured velocities. This method is sel- 
 dom used in irrigation practice because 
 it is time consuming. 
 
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 Typical current-meter notes illustrating the method of recording the data and computing the 
 flow. For each section between two measuring points, the area is taken as the product of the 
 average depth and width; the mean velocity as the average of the mean velocities in the two 
 vertical sections; and the flow as the product of the area and mean velocity. The total flow is 
 the sum of the flows between the sections. 
 
 [7] 
 
In the two-point method, the veloc- 
 ity is determined at 0.2 and 0.8 of the 
 depth. The average of these two measure- 
 ments approximates the mean velocity 
 for ordinary conditions. 
 
 In the single-point method, the 
 
 velocity is determined at a point .6 of 
 the stream depth below the water surface. 
 This method is generally employed at 
 depths less than one foot which is insuffi- 
 cient for the two-point method. 
 
 In the vertical-integration method 
 
 the meter is lowered and raised at a uni- 
 form rate in each of the selected verticals 
 in the measuring section. Due to the pos- 
 sibility of introduction of errors this 
 method is seldom used in routine stream 
 gaging. 
 
 Tracer methods 
 
 Dyes or salts are injected into a stream 
 at a given point and detected down- 
 stream; just as with floats, the velocity 
 is computed from the time the tracer 
 travels down a known distance. Upon in- 
 jecting a small amount of concentrated 
 dye or salt solution; the dissolved mate- 
 rial soon spreads throughout the stream 
 because of turbulence, and extends along 
 the reach of the stream for some distance. 
 Therefore, you must determine the time 
 that the first and last portions of the 
 tracer arrives at the detection point, and 
 use the mean of these times to compute 
 the average velocity of the stream. 
 
 Dyes are preferred because they can 
 be seen readily. Suitable dyes are fluor- 
 escein and potassium permanganate. 
 Salts require an instrument to indicate 
 their presence. 
 
 Once the average velocity is deter- 
 mined, you again can calculate the rate 
 of flow by multiplying average velocity 
 by the average cross section area. No co- 
 efficient of 0.8 (as in the float method) is 
 needed. 
 
 The dye method is also good for de- 
 termining velocities in pipe lines. Inject 
 a small quantity of the dye solution into 
 the water at the intake of the pipe line 
 or at some point along the line. Check 
 time at the instant the coloring matter is 
 introduced and at its first and last ap- 
 pearance at the second point of observa- 
 tion, usually at the outlet of the pipe. To 
 find mean velocity divide the distance in 
 feet by the average time in seconds re- 
 quired for the color to pass through the 
 pipe. To determine flow rate multiply 
 the velocity by the cross sectional area 
 of the pipe. 
 
 Trajectory method 
 
 This method determines the rate of 
 flow discharging from the end of a pipe. 
 Use two measurements of the jet dis- 
 charging from the pipe to calculate the 
 velocity of the water. To determine the 
 rate of flow, measure the area of the jet 
 at the end of the pipe and multiply by 
 the velocity. 
 
 Tracer method determines rate of flow like the float method, needs no coefficient, can be used 
 
 in pipelines. 
 
 [8] 
 
Y^ 
 
 FULL PIPE 
 
 i-F 
 
 PARTLY FILLED PIPE ^X ]\tf_ PIPES NOT HORIZONTAL V U 
 
 For trajectory method find value of Y. Measure H as 12 inches, in full pipes from top of jet, 
 in partly filled pipes from center of jet. For partly filled pipes measure also freeboard F. Then 
 use found values in diagrams on this and the next page. 
 
 For pipes flowing full make the hor- 
 izontal and vertical measurement on the 
 upper surface of the jet; for partly filled 
 pipe make the measurements at the cen- 
 ters of the jet, as shown in the drawings 
 above. By using 12 inches as the value 
 of the vertical distance (H) in field 
 measurements, the values of rate of flow 
 may be obtained from the diagrams. For 
 pipes flowing partly full the amount of 
 
 "freeboard" (F) must also be measured. 
 For full pipes use diagram on this page 
 and for partly full pipes that on page 10. 
 In either case when H equals 12 inches in 
 the field measurement and using the 
 measured value of Y and the diameter of 
 pipe, the rate of flow can be read directly. 
 When H equals 6 inches, multiply the 
 reading on the rate of flow scale by 1.4 
 to obtain the correct discharge. 
 
 100 200 300 400 500 600 700 800 900 IO00 1100 1200 1300 1400 1500 1600 1700 1800 I90O 
 
 Rate of flow in gallons per minute 
 
 TO DETERMINE RATE OF FLOW FOR FULL PIPES by the trajectory method start at value of Y 
 on the left, move horizontally to intersection with diagonal line for size of pipe, then vertically 
 down to find rate of flow in gallons per minute. 
 
 9] 
 
Rate of flow in gallons per minute 
 
 1900 IBOO 1700 1600 1500 1400 1300 1200 1100 IQQQ 9QQ 800 7O0 600 500 400 300 200 100 
 
 TO DETERMINE RATE OF FLOW IN PARTLY FULL PIPES, begin with pipe size at bottom, move 
 vertically to intersection of curve with proper freeboard, F, then across horizontally to diagonal 
 line giving ordinate Y in inches, then vertically to top to find flow rate in gallons per minute. 
 
 with the lower open end facing the cur- 
 Pitot tube method rent and the other end open to the atmos . 
 
 A simple pitot or impact tube is a phere, the water will rise in the tube a 
 small diameter L-shaped tube with both small distance above the water surface of 
 ends open. When immersed in a stream the stream, this distance being equal to 
 
 [10 1 
 
the velocity head, or V 2 /2g. Pitot tubes 
 are used primarily for measuring the 
 flow of water in pipes because the ve- 
 locities encountered in open channels are 
 usually too low to permit accurate meas- 
 urement. When used in pipes it is also 
 necessary to determine the static head, 
 so that either a static piezometer connec- 
 tion must be made in the wall of the pipe, 
 or a combined pitot-static tube is used. 
 This type is usually L-shaped with small 
 holes along the side of the tube about 
 midway between the open tip and the 
 stem to measure the static head. Several 
 standard types of pitot-static tubes have 
 been developed and carefully tested to 
 determine their specific characteristics 
 and limitations. 
 
 Another form of pitot tube has an open 
 stem projecting upstream and one pro- 
 jecting downstream. In this case the total 
 measurable head is somewhat greater 
 than the velocity head, and an appropri- 
 
 ate coefficient is used to obtain the veloc- 
 ity. The Cole pitometer is an instrument 
 of this type, and the value of the coeffi- 
 cient for this instrument has been found 
 to vary from about .86 to .89. 
 
 The transverse tube is another form of 
 impact tube. This consists of a small 
 diameter tube with a small hole or orifice 
 drilled into the side. This tube is inserted 
 through holes in opposite sides of the 
 pipe with the orifice facing upstream 
 where the pressure head is equal to the 
 static head plus the velocity head. When 
 the tube is rotated so the orifice faces 
 downstream, the measured pressure head 
 is essentially equal to the static head 
 less the velocity head. A transverse tube 
 can, therefore, be constructed with two 
 orifices, one on each side of the tube, 
 leading to different ends of the tube. The 
 total differential head thus measured is 
 essentially equal to twice the velocity 
 head. The Collins Flow Gage shown in 
 
 INVERTED U TUBE WATER MANOMETER n 
 
 ( Calibrated rod moves wrth lower indicator ) H 
 
 WATER. 
 
 PRESSURE 
 
 GAUGE 
 
 SECTION WATER PIPE 
 
 Two types of pitot tubes: the Collins flow gage (left) used to measure discharge of pumping plants; 
 and the Cox Flowmeter (right) which permits a reading of velocity with a single measurement. 
 
 [ii] 
 
the drawing on page 11 is an instrument 
 of this kind consisting of an impact tube 
 and a water air manometer. It is exten- 
 sively used by one of the electric power 
 companies in California for measuring 
 the discharge of pumping plants. 
 
 The Cox Flowmeter, page 11, con- 
 sists of a Hall tube which is designed to 
 integrate the velocities across the pipe, 
 and a special water-air monometer. This 
 makes it possible to obtain the mean 
 velocity with a single measurement. The 
 manometer can also be used with other 
 forms of pitot tubes, such as the Prandtl 
 tube, a conventional type of pitot tube, 
 which can be furnished by the same com- 
 pany. 
 
 How to calculate flow. Since most 
 forms of pitot tubes measure the velocity 
 only at one point in the cross section of 
 the pipe, there are different procedures 
 for obtaining the mean velocity, and 
 hence the flow. 
 
 The simplest, but least accurate, 
 method is to place the pitot tube in the 
 center of the pipe where the velocity is 
 usually a maximum, and to apply a co- 
 efficient to obtain the mean velocity. 
 Since the ratio of maximum to mean 
 velocity is affected by many factors, pre- 
 cise measurements are not possible with 
 this method. Tests by the University of 
 California, Davis Campus, on transverse 
 pitot tubes (Collins) have indicated that 
 the velocity determined at the center 
 should be multiplied by a factor of about 
 .94 to obtain the mean velocity. This is a 
 higher coefficient than generally assumed 
 for the ratio of mean velocity to center 
 velocity in a pipe line, and may not apply 
 to other types of pitot tubes. 
 
 Somewhat better accuracy can be ob- 
 tained by taking the velocity at two 
 points, one on each side of the center, 
 at positions where the velocity is approx- 
 imately equal to the mean velocity. It has 
 also been found with transverse tubes 
 that the mean velocity determined at two 
 points gives approximately the mean 
 velocity. These two points are .39 of the 
 
 diameter on each side of the center of 
 the pipe. Collins suggests that such meas- 
 urements be made at points .354 of the 
 diameter on each side of the center of 
 the pipe. 
 
 Still better accuracy can be obtained 
 by making a velocity traverse across the 
 diameter of the pipe. For highest preci- 
 sion traverses are made across two, or 
 even four diameters, and up to ten meas- 
 urements may be made on each diameter. 
 The points are usually taken so that each 
 represents the mean velocity for concen- 
 tric rings of equal area. For a ten point 
 traverse, measurements should be made 
 at points .158, .274, .354, .418, and .474 
 of the diameter from the center of the 
 pipe on each side of the center. For a six- 
 point traverse the positions would be 
 .204, .354, and .456 of the diameter from 
 the center. 
 
 The accuracy of any pitot tube meas- 
 urement will depend upon (a) the accu- 
 racy of calibration of the instrument, 
 (b) the number of points at which ob- 
 servations are made, and (c) the preci- 
 sion with which all measurements are 
 taken, including the manometer read- 
 ings. Very accurate results are possible 
 when the characteristics of the pitot tube 
 are known and all measurements are 
 carefully made. 
 
 Some tests by the University of Cali- 
 fornia at Davis have indicated that the 
 best results under unfavorable flow con- 
 ditions, as near an elbow, gate valve, or 
 pump, can be obtained with the trans- 
 verse tube (Collins tube). 
 
 Slotted tube method 
 
 Recent studies at the University of 
 Minnesota indicated that a slotted tube 
 mounted at or near the end of a discharge 
 pipe with the slot directed upstream can 
 be calibrated and used to measure the 
 rate of flow from a partially full pipe. 
 Arrangement of parts and important 
 dimensions for use of the device in 
 smooth-wall pipes of various diameters 
 are shown in the drawing on page 13. 
 
 [12] 
 
POSITIONING 
 COLLAR v 
 
 1/8 INCH V^ 
 
 SLOTTED jNK^ 
 
 TUBE 
 
 HOSE TO 
 STILLING 
 WELL 
 
 SEDIMENT TRAP-* 
 
 Slotted tube, mounted near end of discharge 
 pipe may be used to measure flow rate from 
 partially full pipe. 
 
 The water level in the slotted tube, 
 measured from the bottom of the pipe, 
 is used as an index of the velocity. For 
 convenience and greater accuracy, the 
 water level is measured in a stilling well 
 which is connected by a hose to the lower 
 end of the tube. The water level can be 
 measured manually with a tape or hook 
 gage, or if a continuous record of the 
 flow is needed, by means of a water stage 
 recorder. 
 
 Flow rates in three sizes of pipes for 
 various gage heights can be found in 
 Table 1, page 25. For other sizes of 
 pipes with diameters within a range of 
 6 to 12 inches, see Table 2, page 25. 
 
 Methods Employing 
 a Formed Constriction 
 
 Methods employing a constriction of 
 predetermined dimensions are most com- 
 monly used in measuring irrigation 
 water. In general, only one or two simple 
 measurements are required if the dimen- 
 sions of the constriction are known. In 
 most cases a table or graph is available 
 for rapid determination of the flow rate. 
 
 Weirs 
 
 A weir is a notch of regular form 
 through which water may flow. Weirs are 
 classified according to the shape of the 
 
 notch; the type of crest; and whether 
 they are contracted or suppressed. Ex- 
 amples of weirs classified according to 
 the shape of notch are: the rectangular 
 contracted weir, the V-notch weir, the 
 Cippoletti weir, and the rectangular sup- 
 pressed weir. 
 
 Types of weir according to crest are: 
 the sharp crested weir, having a sharp 
 upstream edge so formed that the water, 
 in passing, touches only a line; and the 
 broad crested weir, having either a 
 rounded upstream edge or a crest so 
 broad that the water, in passing, comes in 
 contact with a surface. The sharp crested 
 weir, bscause of its greater accuracy, is 
 used almost exclusively for measuring 
 water in a canal or ditch. 
 
 Contracted weirs are those where the 
 crest length is less than the width of the 
 upstream channel; suppressed weirs are 
 those where the crest length is equal to 
 the width of the approach section in the 
 upstream channel. 
 
 Avoid submerged weirs (where the 
 elevation of the downstream water sur- 
 face is higher than the crest of the weir) 
 because additional measurements are re- 
 quired to correct the velocity. 
 
 How to install a weir. The weir, 
 when properly constructed and installed, 
 is one of the simplest and most accurate 
 methods of measuring water. Under ideal 
 conditions it will be accurate within 2 or 
 3 per cent; under most field conditions 
 you may expect accuracy within 5 to 15 
 per cent. You can easily and cheaply con- 
 struct and install a weir by following 
 these simple instructions: 
 
 Set the weir structure in a channel 
 
 that is straight for a distance upstream 
 
 from the weir equal to at least ten 
 
 times the length of the weir crest. 
 Place the weir at right angles to the 
 
 direction of water flow. 
 
 Make sure the face of the weir 
 
 structure is perpendicular, and the 
 
 weir crest straight and level. 
 
 Avoid obstructions on the upstream 
 
 side of the weir structure. 
 
 [13] 
 
H, 
 
 Four types of weir used in California. From 
 top to bottom: 1. rectangular contracted weir, 
 simple and easy to construct. 2. V-notch weir, 
 accurate at very low flow. 3. Cipoletti weir, 
 not as practical as rectangular weir. 4. Rec- 
 tangular suppressed weir, useful for measur- 
 ing water in rectangular flume. 
 
 Make the crest and sides of the weir 
 notch not more than one-eighth of an 
 inch in thickness. 
 
 If possible, set the weir structure at 
 the lower end of a long pool sufficiently 
 wide and deep so that the water will 
 approach the weir free from eddies, at 
 a velocity not exceeding .5 foot per 
 second. 
 
 The height of the crest of the weir 
 above the bottom of the channel, up- 
 stream from the weir, should be at 
 lease twice, and preferably three times, 
 the depth (or head) of the water flow- 
 ing over the crest. Remove debris ac- 
 cumulating behind the weir. 
 
 The distance from the side of the 
 weir notch to the sides of the channel 
 or weir box (except for a suppressed 
 weir) should be at least twice the 
 depth (or head) of water passing over 
 the crest. 
 
 See to it that the length of the weir 
 crest is such that the head to be meas- 
 ured exceeds two inches and the maxi- 
 mum head, preferably is not greater 
 than one-third the length of the weir 
 crest. 
 
 Construct the crest of the weir in a 
 manner that air can circulate freely 
 beneath the overflowing water. 
 
 Measuring the head on a weir. 
 
 Measure the head or depth of water 
 passing over the weir crest at a point 
 upstream from the crest where the sur- 
 face drawdown curve does not affect the 
 measurement. You can do this by driving 
 a stake in the pool at a distance upstream 
 at least six times the maximum head on 
 the weir. Have the top of the stake level 
 with the weir crest. The distance from the 
 top of the stake to the water surface is 
 the head and is measured with a scale. 
 For easier observation you may install a 
 staff gage at the proper place in the pool, 
 with the zero on the gage level with the 
 weir crest. You then may make direct 
 depth readings. For greater accuracy use 
 a hook gage and stilling well. 
 
 [14] 
 
Measuring head on a weir. Measure upstream from downward curve of the water surface. 
 
 Rectangular contracted weirs. 
 
 The rectangular contracted weir takes 
 its name from the location and shape of 
 the opening through which the water 
 flows. It was one of the earliest forms 
 used, and from it all other types have 
 been developed. Because of its simplicity, 
 easy construction, and accuracy when 
 properly used, it is still one of the most 
 popular weirs. Table 3 on page 26 gives 
 the flow over this type of weir in cubic 
 feet per second. 
 
 V-notch weirs. The 90-degree tri- 
 angular or V-notch weir has a greater 
 practical range of capacity than any 
 other type of a given size. Since, how- 
 ever, it requires a greater loss of head, it 
 is better adapted to measuring flows not 
 exceeding 4 cubic feet per second. Due to 
 its shape it is relatively accurate at very 
 low flows. Its shape makes it easy to 
 construct and install with the aid of a 
 carpenter's square and level. Table 4, 
 page 30, gives the flow for this weir in 
 cubic feet per second and gallons per 
 minute. 
 
 Cipolletti weirs. This is a con- 
 tracted trapezoidal weir in which the 
 sides of the notch slope at the scale of 
 one horizontal to four vertical. The dis- 
 charge through the triangular portions 
 at the ends of the weir opening is equal 
 to the decrease in discharge resulting 
 from end contractions. Table 5, page 33, 
 
 gives the flow over Cipolletti weirs in 
 cubic feet per second. 
 
 Rectangular suppressed weirs. 
 
 Having no end contractions, and only 
 bottom contraction, a suppressed weir 
 may be in the form of a flume of uniform 
 cross section, with a vertical weir plate 
 installed near the end. The length of the 
 flume should be at least ten times the 
 length of the weir crest in order to re- 
 move turbulence in the approach section. 
 Provide ventilation under the water fall- 
 ing over the crest, for instance by drilling 
 a small hole on each side of the flume 
 below the downstream edge of the weir 
 crest. The height of the crest above the 
 floor of the weir structure or bottom of 
 the channel should be at least equal to 
 the maximum head to be measured. For 
 good results the head measured should 
 not be greater than 2.0 feet or smaller 
 than .2 foot. 
 
 Table 6, page 37, gives discharges for 
 a weir length of one foot for various weir 
 heights of weir crest above the bottom of 
 channel of approach. For different crest 
 lengths multiply discharges as given for 
 head and weir height by length of weir 
 crest used in feet. 
 
 Limitations in the use of weirs. 
 Weirs, while easy to construct and con- 
 venient to use, may not always be suit- 
 able. They are not accurate unless proper 
 conditions for weir measurements are 
 
 [15] 
 
maintained. Deposition of silt and debris 
 in the stilling basin of the approach sec- 
 tion will reduce the accuracy of the meas- 
 urements. They require a difference in 
 elevation between the water level on the 
 upstream and downstream side of the 
 weir, which sometimes is not easily avail- 
 able in ditches on flat grades. 
 
 Orifices 
 
 Orifices in open channels are usually 
 circular or rectangular openings in bulk- 
 heads placed across the stream. The 
 edges of the openings are sharp and often 
 constructed of metal. The cross-sectional 
 area of the orifice is small in relation to 
 stream cross-section. These conditions 
 allow complete contraction of the stream- 
 flow, and the velocity of approach be- 
 comes negligible. 
 
 Free flowing and submerged orifices. 
 Under free-flow conditions the flow from 
 the orifice discharges entirely into air. If 
 the orifice is fully submerged, the down- 
 stream water level is above the top of the 
 opening, and the flow discharges into 
 water. The drawing below illustrates 
 how measurement of head on submerged 
 and free-flowing orifices are made. 
 
 1. 
 
 Measuring head through orifice. Avoid ori- 
 fices that do not flow free or under complete 
 submergence. 
 
 Avoid partially submerged orifices — 
 with downstream water level below the 
 top of the opening but above the bottom. 
 Complete submergence has little effect on 
 the flow characteristics, but partial sub- 
 mergence makes the head measurement 
 difficult. 
 
 The flow through different size orifices 
 under different heads is given in Table 7 
 on page 41. 
 
 Miner's inch boxes. These are spe- 
 cial forms of free-flowing orifices in 
 which provision is made to maintain a 
 constant predetermined head above the 
 center of the orifice. Since a miner's inch 
 (see box on page 22) is defined as the 
 quantity of water flowing through an 
 area one square inch in cross section 
 under a prescribed head, it is only neces- 
 sary to maintain this head and measure 
 the area of the orifice in square inches. 
 This area is numerically equivalent to 
 the discharge in miner's inches. 
 
 Commercial head-gates 
 
 Commercial head-gates, used to con- 
 trol the quantity of water flowing from 
 one ditch into another, may serve to 
 measure the rate of flow, providing the 
 head and area of opening can be deter- 
 mined and the gate has been calibrated. 
 
 The head is the same as that described 
 for a free-flowing or submerged orifice. 
 
 Normally the gate and the opening 
 into the outlet is circular, and the area 
 can be determined easily if the gate is 
 fully open. However, under most condi- 
 tions the gate is only partially open, leav- 
 ing a crescent-shaped area which is 
 difficult to measure. Consequently, most 
 gates are calibrated and tables supplied, 
 giving the rate of flow as a function of 
 the head and the degree of gate opening 
 as measured by the displacement of the 
 gate stem. 
 
 Parshall flume 
 
 The Parshall flume is a special type of 
 critical flow meter, which is being used 
 widely throughout most of the West. Ad- 
 
 [16] 
 
X 
 
 H^Jfr.i 
 
 Parshall measuring flume is self-cleaning, requires only a small drop, and works 
 even when partly submerged. 
 
 vantages: it is self cleaning, requires 
 only a small amount of drop or head 
 loss in the stream, and allows reasonably 
 accurate measurement even when par- 
 tially submerged. 
 
 The floor of the upsteam section is 
 level and the walls converge toward the 
 throat section. The walls of the throat 
 section are parallel and the floor is in- 
 clined downward. The walls of the down- 
 stream section diverge toward the outlet 
 and the floor is inclined upward. 
 
 The size of the flume is determined by 
 the width of the throat of the flume. Sizes 
 ranging from 3 inches to many feet in 
 throat width have been calibrated and 
 formulas and tables developed. Such 
 flumes must be constructed with specified 
 dimensions and the heads measured at 
 designated points. Where there is consid- 
 erable turbulence within the flume, use 
 stilling wells for making accurate head 
 measurements. Less accurate measure- 
 ments may be obtained from staff gages 
 attached to the sides of the flume at the 
 
 designated points. Because variations in 
 the elevation of the water surface in the 
 stilling well are small, more accurate 
 measurement of the water level can be 
 obtained than is possible by measure- 
 ments in the flume. 
 
 The successful operation of the Par- 
 shall flume depends upon setting the crest 
 of the flume at the proper elevation above 
 the bed of the channel. Where the canal 
 has considerable slope and the banks are 
 high, the flume can be installed with very 
 little trouble. Where the banks are low 
 and the canal has a flat grade, precaution 
 must be taken in choosing the size and in 
 setting the flume. 
 
 Free flow. The discharge through a 
 Parshall flume is called "free flow" when 
 the elevation of the water surface near 
 the downstream end of the throat section 
 is not high enough to cause any retarda- 
 tion of the flow due to back water. Under 
 this condition only one measurement of 
 the water level or head (H a ) in the con- 
 verging section is needed to determine 
 
 [17] 
 
^.60 
 
 Q» .70 
 U 
 
 <*- .60 
 
 • .50 
 
 X .40 
 .35 
 "O 
 
 n .30 
 a> 
 
 ■*= .25 
 
 
 
 
 
 
 
 
 
 ^j- 
 
 
 
 
 
 
 
 
 
 -0.6 
 
 *— < 
 
 >.7- 
 
 =*-■ 
 
 
 
 
 
 
 
 
 
 
 
 
 r 0.4c 
 
 
 0.5 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 3S 
 
 •0.4- 
 
 
 
 
 
 
 
 
 
 a.^j-Ower 
 
 headj- 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 |b - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■ ■ ( 
 
 >.25i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ___ 
 
 
 
 
 
 
 0.2 
 
 
 
 
 
 
 
 
 
 
 
 3-INCH FLUME 
 
 
 
 
 -c 
 
 ' : 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .004 .006 .008 .01 .15 .02 03 .04 .05 .06 .08 0.1 .15 .20 .25 30 .40 
 
 Correction — cubic feet per second 
 
 +. 1.0 
 
 » .90 
 
 £ .80 
 
 .70 
 
 1 .60 
 
 <v 
 
 r .50 
 
 -o .4o^ 
 
 a) 
 .30 
 
 » .25 
 a. 
 => .20 
 
 
 
 
 
 
 
 
 
 
 ^< 
 
 
 L 
 
 
 
 0.8 
 
 
 
 0.9- 
 
 
 
 
 
 
 
 
 N 
 
 
 
 
 ^\^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 
 
 
 
 >.6- 
 
 *- 0.? 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 FO.S 
 
 5 — 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 "~ 0.4 
 
 
 
 
 
 
 
 
 
 
 \^^ 
 
 
 
 
 
 
 
 
 — 
 
 0.3 
 
 5- 
 
 0.4 . 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 -0.3^. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■*. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■~" - — 
 
 J. 2 
 
 owe 
 
 r___ 
 
 head' H b ' -feet 
 
 
 
 6-INcn 
 
 | 
 
 FLOivi 
 
 | | 
 
 .01 .015 .02 .03 .04 .05 .06 .08 0.1 0.15 0.2 0.3 0.4 0.5 0.6 0.8 1.0 
 
 Correction — cubic feet per second 
 
 .03 .04.05 .06 .08 .10 .15 0.2 
 
 Correction — cubi 
 
 0.3 0.4 0.5 0.6 0.8. 1.0 1.6 2.0 2.5 
 
 c feet per second 
 
 0.1 0.15 0.2 0.3 0.4 0.5 0.6 
 
 Correction — cubi 
 
 0.8 1.0 1.5 2.0 2.5 3.0 4.0 5.0 6.0 7.0 
 
 c feet per second 
 
 Correction diagrams for determining submerged flow through Parshall measuring flumes. 
 Subtract the amount obtained from this diagram from table 8 for the same upper head, H a . For 
 larger flumes, use diagram for the 1-foot flume and multiply correction by the factor given in 
 table 9. 
 
 [18] 
 
the rate of flow. Free flow discharge for 
 various sizes of Parshall flumes is given 
 in Table 8, page 44. 
 
 Submerged flow. Where the flow is 
 submerged, it is necessary to install an 
 "H b " gage near the lower end of the 
 throat section as illustrated in the draw- 
 ing on page 17. 
 
 When the relation of the two heads, 
 
 (£)• 
 
 exceeds 0.7 a correction is sub- 
 
 tracted from free flow conditions to 
 obtain the correct rate of flow. This cor- 
 rection is determined by use of the charts 
 on page 18. For large flumes multiply the 
 correction for the 1-foot flume by the 
 factor (M) given in a table on page 24. 
 This value is then subtracted from the 
 free-flow discharge to obtain the cor- 
 rected flow. 
 
 Miscellaneous devices 
 
 Small venturi flumes. In irrigation 
 evaluation work it has been found advan- 
 tageous to use a small Venturi flume to 
 measure water in furrows. These flumes 
 consist of only a converging section. 
 Normally they are constructed of metal 
 and require calibration to determine flow 
 characteristics. 
 
 Siphons and pipe turnouts. Al- 
 though siphons and pipe are used to 
 deliver water from a ditch to a furrow 
 or check, they can be used to measure 
 the rate of flow being delivered. The 
 drawing below shows the method of 
 measuring the head. Once the head is 
 determined the rate of flow can be found 
 directly in the diagram on page 20 for 
 pipe turnouts, in the diagram on page 
 21 for siphons. 
 
 'ATER SURFACE 7 ^0 T ^ T9f %^ 
 
 V ELECTIVE HEAD (H) 
 WATER SURFACE 
 
 ))M V^VVVV/VW//// 
 
 EFFECTIVE HEAD (H) 
 
 WATER SURFACE 
 
 ^rnwTTf^^ 
 
 J^ V\ !/// \\\ U//VWi\v\v 
 
 WATER SURFACE 
 
 HEAD (HI 
 
 WATER SURFACE 
 
 Measuring head on spiles and siphons. For free-flowing spiles (top) measure head as difference 
 in elevation between water in the ditch and the center of the downstream end of the spile. For 
 submerged spiles or siphons (center and bottom) measure difference in elevation of water in 
 ditch and water in field. 
 
 [19] 
 
Rate of flow through large pipe 
 
 1 c 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 10 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 r 
 
 /6" 
 
 
 8" 
 
 
 10" 
 
 
 Az 
 
 •i 
 
 
 /\A 
 
 II 
 
 
 NCHES 
 
 - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■ 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 S 6 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 a 
 
 < 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■/ 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 -/, 
 
 '/ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 // 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 - , 
 
 
 1 
 
 1 
 
 L_ 
 
 L ■ 
 
 1 J 
 
 1 
 
 
 
 i_ 
 
 
 1 
 
 ( 
 
 10 2.0 3.0 4.0 5.0 
 
 CUBIC FEET PER SECOND 
 
 6.0 
 
 7.0 
 
 To determine rate of flow start at left, move horizontally from point of measured head to the size 
 of pipe (or siphon), then vertically down to find rate of flow in cubic feet per second. 
 
 Rate of flow through small pipe 
 
 10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 (H) INCHES 
 
 • 
 
 1" 
 
 
 ■Jfc" 
 
 
 4 m 
 
 
 
 
 
 
 A u 
 
 
 
 - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 " 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 a 
 2 4 
 
 X 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 L / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 7 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 // 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 r% 
 
 » f 
 
 i 
 
 i 
 
 , i 
 
 
 1 1 
 
 i i 
 
 i 
 
 LJ 
 
 , , 1 J 
 
 L^ 
 
 i 
 
 i . 
 
 . i . 
 
 20 40 60 80 100 
 
 6ALL0NS PER MINUTE 
 
 120 
 
 140 
 
 [20] 
 
Rate of flow through small siphons 
 
 12 
 
 iO 
 
 CO 
 
 id 
 
 x 8 
 o 
 
 z 
 
 ^ 6 
 
 I 
 
 5 4 
 
 
 
 
 
 
 
 
 
 
 
 n^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 - \ww* 
 
 
 
 /z" 
 
 
 / l /2 
 
 
 
 *v 
 
 ^t££ 
 
 
 
 
 
 
 
 
 
 / 
 
 / / 
 
 
 
 
 
 
 
 
 ^JJ 
 
 
 
 
 
 
 
 
 
 
 // 
 
 
 
 
 
 
 
 
 
 
 40 
 
 
 
 
 
 
 
 
 
 
 i£ 
 
 
 
 
 
 
 
 
 
 
 /// 
 
 
 
 
 
 
 
 
 
 
 f wf * 
 
 1 
 
 1 
 
 1 
 
 i 
 
 i 
 
 1 
 
 , 
 
 1 
 
 1 
 
 12 
 
 CO 
 
 C 6 
 
 10 20 30 40 50 60 70 80 90 100 
 
 GALLONS PER MINUTE 
 
 Rate of flow through large siphons 
 
 - 1 
 
 / / 
 
 
 
 
 
 
 
 - 
 
 / / 
 
 
 
 
 
 
 
 - 
 
 / / 
 
 
 
 
 
 
 
 - «' 
 
 U"h" 
 
 
 8" 
 
 /o" 
 
 
 At" 
 
 
 ■ 
 
 / / 
 
 
 
 
 
 
 
 // 
 
 
 
 
 
 
 
 // 
 
 
 
 
 
 
 
 
 // 
 
 
 
 
 
 
 
 
 J 
 
 
 
 
 
 
 
 
 ■ 
 
 
 
 
 
 
 
 
 /// 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 0.5 10 1.5 2.0 2.5 30 3.5 4.0 
 
 CUBIC FEET PER SECOND 
 
 [21 
 
Units of Water Measurements 
 
 Irrigation water is measured in volume 
 and flow units. 
 
 In some areas you want to know only 
 the total volume of water used, as water 
 is often purchased on that basis; in other 
 cases it is important to know the rate of 
 flow — the volume of water used during 
 a certain time. 
 
 Volume units. The commonly used 
 volume units include: cubic feet (cu. ft.) , 
 gallon (gal.), acre-inch (ac.-in.), acre- 
 feet, (ac.-ft.), and miner's inch hours 
 (MI-Hr.). 
 
 Flow units. The common units of flow 
 are combinations of the above volume 
 units with a convenient time unit. They 
 are: cubic feet per second (cu. ft. per 
 sec. or c.f.s.), gallons per minute 
 (g.p.m.), acre-inches per hour, acre-feet 
 per (24-hour) day, and miner's inches 
 (M.I.). 
 
 Cubic foot per second, sometimes writ- 
 ten second-foot (sec. ft. or cusec.) , is the 
 generally accepted standard unit of flow 
 in the American system. 
 
 Gallons per minute is the most com- 
 monly used term for expressing flow from 
 pumps. 
 
 A flow of one cubic-foot per second is 
 approximately equal to one acre-inch per 
 hour, 2 acre-feet per day, or 450 gallons 
 per minute. 
 
 The miner's inch is an ambiguous 
 measurement, and therefore not satisfac- 
 
 tory as a unit for measuring flow. A brief 
 survey of the variations of the miner's 
 inch are given in the box on this page. 
 If you use the miner's inch, state the 
 head under which it is measured, or its 
 equivalent in cubic feet per second. 
 
 What is a miner's inch? 
 
 In general: The flow of water through 
 an opening with an area of 1 square 
 inch under a head which varies in dif- 
 ferent localities from 4 to 6 inches. (The 
 head is the vertical distance from the 
 upstream water surface to the center of 
 the opening, when the opening is free- 
 flowing— see drawing on page 16.) 
 
 In northern California: The flow 
 through an orifice with an area of 1 
 square inch under a head of 6 inches. 
 This is the "statutory miner's inch"— the 
 flow of IV2 cubic feet per minute (1/40 
 cu. ft. per sec. or approximately 1114 
 g.p.m.)— in the California foothills, Ari- 
 zona, Nevada, Oregon, and Montana. 
 
 In southern California: The flow 
 through an orifice with an area of 1 
 square inch under a head of 4 inches 
 (approximately 1/50 cu. ft. per sec. or 
 9 g.p.m.). This is the "statutory miner's 
 inch" in Idaho, New Mexico, Utah, and 
 Washington. 
 
 Others: In Colorado, 1 38.4 cu. ft. 
 per sec; in British Columbia, 1/35.7 cu. 
 ft. per sec. 
 
 [22 
 
List of Equivalents 
 
 The following equivalents may be used for converting from one unit to another 
 and for computing volumes from flow units: 
 
 Volume Units 
 
 One acre-inch 
 
 = 3,630 cubic feet 
 = 27,154 gallons 
 = Y 12 acre-foot 
 
 One acre-foot 
 
 = 43,560 cubic feet 
 = 325,851 gallons 
 = 12 acre-inches 
 
 One cubic foot 
 
 = 1,728 cubic inches 
 = 7.481 (approximately 7.5) gallons 
 weighs approximately 62.4 pounds 
 (62.5 for ordinary calculations) 
 
 One gallon 
 
 = 231 cubic inches 
 
 = 0.13368 cubic foot 
 
 weighs approximately 8.33 pounds 
 
 Rate of Flow Units 
 
 One cubic foot per second 
 
 = 448.83 (approximately 450) gallons per minute 
 
 = 50 Southern California miner's inches 
 
 = 40 California statutory miner's inches 
 
 = 1 acre-inch in 1 hour and 30 seconds (approximately 1 hour) , or 0.992 
 
 (approximately 1) acre-inch per hour 
 = 1 acre-foot in 12 hours and 6 minutes (approximately 12 hours), or 
 
 1.984 (approximately 2) acre-feet per day (24 hours) 
 
 One gallon per minute 
 
 = 0.00223 (approximately % 50 ) cubic foot per second 
 
 = 0.1114 (approximately %) Southern California miner's inch 
 
 = 0.0891 (approximately x /\\) California statutory miner's inch 
 
 = 1 acre-inch in 452.6 (approximately 450) hours, or 0.00221 acre-inch 
 
 per hour 
 = 1 acre-foot in 226.3 days, or 0.00442 acre-foot per day 
 = 1 inch depth of water over 96.3 square feet in 1 hour 
 
 Million gallons per day 
 
 = 1.547 cubic feet per second 
 
 = 694.4 gallons per minute 
 
 = 77.36 Southern California miner's inches 
 
 = 61.89 California statutory miner's inches 
 
 [23] 
 
One Southern California miner's inch 
 = 0.02 (%o) cubic foot per second 
 = 8.98 (approximately 9) gallons per minute 
 = 0.80 {%) California statutory miner's inch 
 = 1 acre-inch in 50 hours and 25 minutes, or 0.0198 (approximately Y 50 ) 
 
 acre-inch per hour 
 = 1 acre-foot in 605 hours (approximately 25 days) , or 0.0397 (approxi- 
 mately I/25 ) acre-foot per day 
 
 One California statutory miner's inch 
 
 = 0.025 (/4o) cubic foot per second 
 
 = 11.22 (approximately 11%) gallons per minute 
 
 = 1.25 Southern California miner's inches 
 
 = 1 acre-inch in 40 hours and 20 minutes, or 0.0248 approximately % ) 
 acre-inch per hour 
 
 = 1 acre-foot in 484 hours (approximately 20 days) , or 0.0496 (approxi- 
 mately Yoq) acre-foot per day 
 
 Conversion Table for Units of Flow 
 
 Units 
 
 Cubic 
 feet 
 per 
 
 second 
 
 Gallons 
 
 per 
 minute 
 
 Million 
 gallons 
 
 per 
 
 day 
 
 Southern 
 
 Calif, 
 miner's 
 inches 
 
 Calif. 
 
 statutory 
 
 miner's 
 
 inches 
 
 Acre- 
 inches 
 per 24 
 hours 
 
 Acre- 
 feet 
 per 24 
 hours 
 
 Cubic feet per second 
 
 Gallons per minute 
 
 Million gallons per day 
 
 So. Calif, miner's inches .... 
 Calif, statutory miner's 
 inches 
 
 1.0 
 
 0.00222 
 1.547 
 0.020 
 
 0.025 
 0.042 
 0.504 
 
 448.8 
 1.0 
 
 694.4 
 8.98 
 
 11.22 
 18.86 
 226.3 
 
 0.646 
 0.00144 
 1.0 
 0.0129 
 
 0.0162 
 0.0271 
 0.3259 
 
 50.0 
 
 0.1114 
 77.36 
 
 1.0 
 
 1.25 
 
 2.10 
 
 25.21 
 
 40.0 
 
 0.0891 
 61.89 
 
 0.80 
 
 1.0 
 
 1.68 
 
 20.17 
 
 23.80 
 0.053 
 
 36.84 
 0.476 
 
 0.595 
 1.0 
 12.0 
 
 1.984 
 0.00442 
 3.07 
 0.0397 
 
 0.0496 
 
 Acre-inches per 24 hours 
 
 Acre-feet per 24 hours 
 
 0.0833 
 1.0 
 
 field: 
 
 The following approximate formulas may be conveniently used to compute the depth of water applied to a 
 
 Cu. ft. per sec. X hours 
 
 Acres 
 Gal. per min. X hours 
 
 450 X acres 
 Southern California miner's inches X hours 
 
 50 X acres 
 California statutory miner's inches X hours 
 
 40 X acres 
 
 = acre-inches per acre, or average depth in inches, 
 acre-inches per acre, or average depth in inches. 
 
 acre-inches per acre, or average depth in inches. 
 
 acre-inches per acre, or average depth in inches. 
 
 Correction Factors for Submerged Flow 
 
 Size of 
 flume 
 
 W (feet) 
 
 1 
 
 Multiplying 
 
 factor, 
 
 M 
 
 1.0 
 
 Size of 
 
 flume 
 
 W (feet) 
 
 5 
 
 Multiplying 
 
 factor, 
 
 M 
 
 3.7 
 
 1.5 
 
 1.4 
 
 6 
 
 4.3 
 
 2 
 
 1.8 
 
 7 
 
 4.9 
 
 3 
 
 2.4 
 
 8 
 
 5.4 
 
 4 
 
 3.1 
 
 10 
 
 6.4 
 
 
 
 [24] 
 
Tables 
 
 Table 1. Flow Rates for Slotted-Tube Flow Meter in 6, 8, and 10-inch 
 Pipes with Slopes Up to .25 per cent* 
 
 
 Discharge in gallons per minute for : 
 
 Gage height (feet) 
 
 6" Pipe 
 (i.d.f = 5.874") 
 
 8" Pipe 
 (i.d.f = 7.812") 
 
 10" Pipe 
 (i.d.f = 10.0") 
 
 
 
 .05 
 
 .10 
 
 
 1.6 
 
 7.4 
 18.4 
 
 36.0 
 
 57.2 
 
 81.4 
 
 109.2 
 
 139.2 
 165.6 
 192.0 
 218.8 
 
 
 
 2.0 
 
 8.0 
 
 24.5 
 
 40.0 
 65.0 
 94.5 
 127 
 
 166 
 208 
 252 
 298 
 
 346 
 393 
 438 
 481 
 
 
 
 4 
 13 
 
 .15 
 
 .20 
 
 28 
 50 
 
 .25 
 
 80 
 
 .30 
 
 117 
 
 .35 
 
 162 
 
 .40 
 
 212 
 
 .45 
 
 .50 
 
 .55 
 
 .60 
 
 .65 
 
 .70 
 
 .75 
 
 .80 
 
 .85 
 
 .90 
 
 271 
 332 
 400 
 
 470 
 542 
 616 
 690 
 
 764 
 839 
 912 
 
 * From University of Minnesota data. 
 f Inside diameter. 
 
 Table 2. Flow Rates for Slotted-Tube Flow Meter, Independent of 
 Pipe Diameter with Slopes Up to .25 per cent* 
 
 H/Df 
 
 D 6 ' 2 
 
 H/Df 
 
 Qt 
 
 
 
 .000 
 
 .60 
 
 1.04 
 
 .10 
 
 .020 
 
 .70 
 
 1.38 
 
 .20 
 
 .093 
 
 .80 
 
 1.75 
 
 .30 
 
 .247 
 
 .90 
 
 2.14 
 
 .40 
 
 .452 
 .731 
 
 1.00 
 
 2.52 
 
 .50 
 
 1.10 
 
 2.88 
 
 
 
 
 * From University of Minnesota data. 
 t Head (H) divided by Diameter (D). 
 t Flow in en. ft. per sec. (Q) divided by Diameter to the five-half power (D 5 ^). 
 
 [25] 
 
Table 3. Flow Over Rectangular Contracted Weirs 
 in Cubic Feet per Second* 
 
 Head 
 
 in inches, 
 
 approx. 
 
 Crest length (L) 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 Flow in cubic feet per second 
 
 1J* 
 
 1% 
 
 We 
 
 1% 
 
 1% 
 2% 
 
 2% 
 
 2% 
 2V 2 
 2% 
 2% 
 
 2% 
 
 3 
 
 sy 2 
 
 3% 
 3% 
 3% 
 
 4>ie 
 
 ±% 
 
 4% 
 
 5M 
 
 0.105 
 0.121 
 0.137 
 0.155 
 0.172 
 
 0.191 
 0.210 
 0.229 
 0.249 
 0.270 
 
 0.291 
 0.312 
 0.335 
 0.358 
 0.380 
 
 0.404 
 0.428 
 0.452 
 0.477 
 0.502 
 
 0.527 
 0.553 
 0.580 
 0.606 
 0.634 
 
 0.661 
 0.688 
 0.717 
 0.745 
 0.774 
 
 0.804 
 0.833 
 0.863 
 0.893 
 0.924 
 
 0.158 
 0.182 
 0.207 
 0.233 
 0.260 
 
 0.288 
 0.316 
 0.346 
 0.376 
 0.407 
 
 0.439 
 0.472 
 0.505 
 0.539 
 0.574 
 
 0.609 
 0.646 
 0.682 
 0.720 
 0.758 
 
 0.796 
 0.836 
 0.876 
 0.916 
 0.957 
 
 0.999 
 
 1.04 
 
 1.08 
 
 1.13 
 
 1.17 
 
 1.21 
 1.26 
 1.30 
 1.35 
 1.40 
 
 0.212 
 0.244 
 0.277 
 0.312 
 0.348 
 
 0.385 
 0.423 
 0.463 
 0.504 
 0.546 
 
 0.588 
 0.632 
 0.677 
 0.723 
 0.769 
 
 0.817 
 0.865 
 0.914 
 0.965 
 1.02 
 
 1.07 
 1.12 
 1.18 
 1.23 
 1.28 
 
 1.34 
 1.40 
 1.45 
 1.51 
 1.57 
 
 1.63 
 1.69 
 1.75 
 1.81 
 1.88 
 
 0.319 
 0.367 
 0.418 
 0.470 
 0.524 
 
 0.581 
 0.638 
 0.698 
 0.760 
 0.823 
 
 0.887 
 
 0.954 
 
 1.02 
 
 1.09 
 
 1.16 
 
 1.23 
 1.31 
 1.38 
 1.46 
 1.53 
 
 1.61 
 1.69 
 1.77 
 1.86 
 1.94 
 
 2.02 
 2.11 
 2.20 
 2.28 
 2.37 
 
 2.46 
 2.55 
 2.65 
 2.74 
 2.83 
 
 0.427 
 0.491 
 0.559 
 0.629 
 0.701 
 
 0.776 
 
 0.854 
 
 0.934 
 
 1.02 
 
 1.10 
 
 1.19 
 1.28 
 1.37 
 
 1.46 
 1.55 
 
 1.65 
 1.75 
 1.85 
 1.95 
 2.05 
 
 2.16 
 2.26 
 2.37 
 2.48 
 2.60 
 
 2.71 
 2.82 
 2.94 
 3.06 
 3.18 
 
 3.30 
 3.42 
 3.54 
 3.67 
 3.80 
 
 * Computed from Cone's formula: Q = 3.247 LH 1 ••■» 
 
 0.566 L' s 
 1 +2L'-s 
 
 Hi-*. 
 
 [26] 
 
Table 3 (Continued). Flow Over Rectangular Contracted Weirs 
 
 Head 
 
 in inches, 
 
 approx. 
 
 5% 
 5 5 A 
 5V 8 
 6 
 
 VA 
 
 6^ 
 &A 
 6% 
 6% 
 7^ 
 
 7H 
 
 *7% 
 7^6 
 1% 
 1% 
 
 1% 
 
 7% 
 8>16 
 
 8M 
 
 8^ 
 83^ 
 8^ 
 8% 
 SH 
 
 9 
 
 9M 
 
 Crest length (L) 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 Flow in cubic feet per second 
 
 0.955 
 
 0.986 
 
 1.02 
 
 1.05 
 
 1.08 
 
 1.11 
 1.15 
 1.18 
 1.21 
 1.25 
 
 1.28 
 1.31 
 1.35 
 1.38 
 1.42 
 
 1.45 
 1.49 
 1.52 
 1.56 
 1.60 
 
 1.63 
 1.67 
 1.71 
 1.74 
 1.78 
 
 1.82 
 1.86 
 1.90 
 1.93 
 1.97 
 
 2.01 
 2.05 
 2.09 
 2.13 
 2.17 
 
 1.44 
 1.49 
 1.54 
 1.59 
 1.64 
 
 1.68 
 1.73 
 1.78 
 1.84 
 1.89 
 
 1.94 
 1.99 
 2.04 
 2.09 
 2.15 
 
 2.20 
 2.25 
 2.31 
 2.36 
 2.42 
 
 2.47 
 2.53 
 2.59 
 2.64 
 2.70 
 
 2.76 
 2.81 
 2.87 
 2.93 
 2.99 
 
 3.05 
 3.11 
 3.17 
 3.23 
 3.29 
 
 1.94 
 2.00 
 2.07 
 2.13 
 2.20 
 
 2.26 
 2.33 
 2.40 
 2.46 
 2.53 
 
 2.60 
 2.67 
 2.74 
 2.81 
 2.88 
 
 2.96 
 3.03 
 3.10 
 3.17 
 3.25 
 
 3.32 
 3.40 
 3.47 
 3.56 
 3.63 
 
 3.71 
 3.78 
 3.86 
 3.94 
 4.02 
 
 4.10 
 4.18 
 4.26 
 4.34 
 4.42 
 
 2.93 
 3.03 
 3.12 
 3.22 
 3.32 
 
 3.42 
 3.52 
 3.62 
 3.73 
 3.83 
 
 3.94 
 4.04 
 4.15 
 4.26 
 4.36 
 
 4.47 
 4.59 
 4.69 
 4.81 
 4.92 
 
 5.03 
 5.15 
 5.26 
 5.38 
 5.49 
 
 5.61 
 5.73 
 5.85 
 5.97 
 6.09 
 
 6.21 
 6.33 
 6.45 
 6.58 
 6.70 
 
 3.93 
 4.05 
 4.18 
 4.32 
 4.45 
 
 4.58 
 4.72 
 4.86 
 4.99 
 5.13 
 
 5.27 
 5.42 
 5.56 
 5.70 
 5.85 
 
 6.00 
 6.14 
 6.29 
 6.44 
 6.59 
 
 6.75 
 6.90 
 7.05 
 7.21 
 7.36 
 
 7.52 
 7.68 
 7.84 
 8.00 
 8.17 
 
 8.33 
 8.49 
 8.66 
 8.82 
 8.99 
 
 [27] 
 
Table 3 (Continued). Flow Over Rectangular Contracted Weirs 
 
 Head 
 
 in inches, 
 
 approx. 
 
 9% 
 9% 
 9% 
 9% 
 10% 
 
 10% 
 10% 
 
 io% 
 
 10% 
 10% 
 
 10% 
 10% 
 
 11% 
 11% 
 
 n% 
 
 ii^ 
 n% 
 n% 
 n% 
 n% 
 
 12 
 
 12% 
 12% 
 12% 
 12% 
 
 12% 
 12% 
 12% 
 12% 
 13% 
 
 13% 
 13% 
 13% 
 13% 
 13% 
 
 Crest length (L) 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 Flow in cubic feet per second 
 
 2.21 
 2.25 
 2.29 
 2.33 
 2.37 
 
 2.41 
 2.46 
 2.50 
 2.54 
 2.58 
 
 2.62 
 2.67 
 2.71 
 2.75 
 2.79 
 
 2.84 
 2.88 
 2.93 
 2.97 
 3.01 
 
 3.06 
 
 3.35 
 3.41 
 3.47 
 3.54 
 3.60 
 
 3.66 
 3.72 
 3.79 
 3.85 
 3.92 
 
 3.98 
 4.05 
 4.11 
 4.18 
 4.24 
 
 4.31 
 4.37 
 
 4.44 
 4.51 
 4.57 
 
 4.64 
 4.71 
 4.78 
 4.85 
 4.92 
 
 4.98 
 5.05 
 5.12 
 5.20 
 5.26 
 
 5.34 
 5.41 
 5.48 
 5.55 
 5.62 
 
 4.51 
 4.59 
 4.67 
 4.75 
 4.84 
 
 4.92 
 5.01 
 5.10 
 5.18 
 5.27 
 
 5.35 
 
 5.44 
 5.53 
 5.62 
 5.71 
 
 5.80 
 5.89 
 5.98 
 6.07 
 6.15 
 
 6.25 
 6.34 
 6.43 
 6.52 
 6.62 
 
 6.71 
 6.80 
 6.90 
 6.99 
 7.09 
 
 7.19 
 7.28 
 7.38 
 7.47 
 7.57 
 
 6.83 
 6.95 
 7.08 
 7.21 
 7.33 
 
 7.46 
 7.59 
 7.72 
 7.85 
 7.99 
 
 8.12 
 8.25 
 8.38 
 8.52 
 8.65 
 
 8.79 
 8.93 
 9.06 
 9.20 
 9.34 
 
 9.48 
 9.62 
 9.76 
 9.90 
 10.04 
 
 10.18 
 10.32 
 10.46 
 10.61 
 10.75 
 
 10.90 
 11.04 
 11.19 
 11.34 
 11.48 
 
 9.16 
 9.33 
 9.50 
 9.67 
 9.84 
 
 10.01 
 10.19 
 10.36 
 10.54 
 10.71 
 
 10.89 
 11.07 
 11.25 
 11.43 
 11.61 
 
 11.79 
 11.98 
 12.16 
 12.34 
 12.53 
 
 12.72 
 12.91 
 13.10 
 13.28 
 13.47 
 
 13.66 
 13.85 
 14.04 
 14.24 
 14.43 
 
 14.64 
 14.83 
 15.03 
 15.22 
 15.42 
 
 [28] 
 
Table 3 {Concluded). Flow Over Rectangular Contracted Weirs 
 
 Head 
 
 in inches, 
 
 approx. 
 
 13% 
 13% 
 14% 
 14% 
 14 % 
 
 14% 
 143^ 
 14% 
 14 % 
 14% 
 
 15 
 
 15% 
 15% 
 15% 
 15% 
 
 15% 
 15% 
 
 15% 
 15% 
 16% 
 
 16% 
 16% 
 16% 
 16% 
 16% 
 
 16% 
 16% 
 17% 
 17% 
 17% 
 
 17% 
 17% 
 
 17% 
 17% 
 
 177% 
 
 18 
 
 Crest length (L) 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 Flow in cubic feet per second 
 
 5.69 
 5.77 
 5.84 
 5.91 
 5.98 
 
 6.06 
 6.13 
 6.20 
 6.28 
 6.35 
 
 6.43 
 
 7.66 
 7.76 
 7.86 
 7.96 
 8.06 
 
 8.16 
 8.26 
 8.35 
 8.46 
 8.56 
 
 8.66 
 
 11.64 
 11.79 
 11.94 
 12.09 
 12.24 
 
 12.39 
 12.54 
 12.69 
 12.85 
 12.99 
 
 13.14 
 13.30 
 13.45 
 13.61 
 
 13.77 
 
 13.93 
 14.09 
 14.24 
 14.40 
 14.56 
 
 14.72 
 14.88 
 15.04 
 15.20 
 15.36 
 
 15.53 
 15.69 
 15.85 
 16.02 
 16.19 
 
 16.34 
 16.51 
 16.68 
 16.85 
 17.01 
 
 17.17 
 
 15.62 
 15.82 
 16.02 
 16.23 
 16.43 
 
 16.63 
 16.83 
 17.03 
 17.25 
 
 17.45 
 
 17.65 
 17.87 
 18.07 
 18.28 
 18.50 
 
 18.71 
 18.92 
 19.12 
 19.34 
 19.55 
 
 19.77 
 19.98 
 20.20 
 20.42 
 20.64 
 
 20.86 
 21.08 
 21.29 
 21.52 
 21.74 
 
 21.96 
 22.18 
 22.41 
 22.64 
 22.85 
 
 23.08 
 
 For each 
 additional 
 foot of crest 
 in excess 
 of 4 ft. 
 (approx.) 
 
 3.98 
 4.03 
 4.08 
 4.14 
 4.19 
 
 4.24 
 4.29 
 4.34 
 4.40 
 4.46 
 
 4.51 
 4.57 
 4.62 
 4.67 
 4.73 
 
 4.78 
 4.82 
 4.88 
 4.94 
 4.99 
 
 5.05 
 5.10 
 5.16 
 5.22 
 5.28 
 
 5.33 
 5.39 
 5.44 
 5.50 
 5.55 
 
 5.62 
 5.67 
 5.73 
 5.79 
 5.84 
 
 5.91 
 
 29 
 
Table 4. Flow Over 90° V Notch Weir in Cubic Feet per Second 
 and Gallons per Minute* 
 
 Head in feet 
 "H" 
 
 Head in inches 
 approximately 
 
 Flow in cubic feet 
 per second 
 
 Flow in gallons 
 per minute 
 
 0.10 
 
 We 
 
 1H 
 
 l% 
 1% 
 
 l% 
 1% 
 2^ 
 2% 
 
 2M 
 
 2% 
 2V 2 
 2% 
 2% 
 2% 
 
 3 
 
 3^ 
 3^ 
 
 3 l A 
 
 3M 
 3% 
 3% 
 We 
 
 4% 
 
 4% 
 4% 
 
 4% 
 4% 
 
 5^6 
 
 5M 
 
 5^8 
 
 5V 2 
 5Vs 
 5% 
 
 5Vs 
 
 0.008 
 0.010 
 0.012 
 0.016 
 0.019 
 
 0.022 
 0.026 
 0.031 
 0.035 
 0.040 
 
 0.046 
 0.052 
 0.058 
 0.065 
 0.072 
 
 0.080 
 0.088 
 0.096 
 0.106 
 0.115 
 
 0.125 
 0.136 
 0.147 
 0.159 
 0.171 
 
 0.184 
 0.197 
 0.211 
 0.226 
 0.240 
 
 0.256 
 0.272 
 0.289 
 0.306 
 0.324 
 
 0.343 
 0.362 
 0.382 
 0.403 
 0.424 
 
 3.6 
 
 0.11 
 
 4.5 
 
 0.12 
 
 5.4 
 
 0.13 . 
 
 7.2 
 
 0.14 
 
 8.5 
 
 0.15 
 
 9.9 
 
 0.16 
 
 11.7 
 
 0.17 . 
 
 13.9 
 
 0.18 
 
 15.7 
 
 0.19 
 
 18.0 
 
 0.20 
 
 20.6 
 
 0.21.. 
 
 23.3 
 
 0.22. . 
 
 26.0 
 
 0.23. 
 
 29.2 
 
 0.24 
 
 32.3 
 
 0.25 
 
 35.9 
 
 0.26 
 
 39.5 
 
 0.27 
 
 43.1 
 
 0.28 
 
 47.6 
 
 0.29 
 
 51.6 
 
 0.30 
 
 56.1 
 
 0.31 
 
 61.0 
 
 0.32.. . . 
 
 66.0 
 
 0.33. 
 
 71.4 
 
 0.34. . 
 
 76.7 
 
 0.35 
 
 82.6 
 
 0.36 
 
 88.4 
 
 0.37. . 
 
 94.7 
 
 0.38 
 
 *101.0 
 
 0.39 
 
 108.0 
 
 0.40 
 
 115 
 
 0.41. . 
 
 122 
 
 0.42 
 
 130 
 
 0.43. . 
 
 137 
 
 0.44 
 
 145 
 
 0.45 
 
 154 
 
 0.46 
 
 162 
 
 0.47 
 
 171 
 
 0.48 
 
 181 
 
 0.49 
 
 190 
 
 
 
 Computed from Cone's formulas: Q = 2.49 H-'- 48 
 
 GPM = 448.8 (2.49 H=- 48 ). 
 
 [30] 
 
Table 4 (Continued). Flow over 90° V Notch Weir 
 
 Head in feet 
 "H" 
 
 Head in inches 
 approximately 
 
 Flow in cubic feet 
 per second 
 
 Flow in gallons 
 per minute 
 
 0.50 
 0.51 
 0.52 
 0.53 
 0.54 
 
 0.55 
 0.56 
 0.57 
 0.58 
 0.59 
 
 0.60 
 0.61 
 0.62 
 0.63 
 0.64 
 
 0.65 
 0.66 
 0.67 
 0.68 
 0.69 
 
 0.70 
 0.71 
 0.72 
 0.73 
 0.74 
 
 0.75 
 0.76 
 0.77 
 0.78 
 0.79 
 
 0.80 
 0.81 
 0.82 
 0.83 
 0.84 
 
 0.85 
 0.86 
 0.87 
 0.88 
 0.89 
 
 6 
 
 VA 
 
 &A 
 &A 
 G% 
 G% 
 1A 
 
 l z A 
 1% 
 l 7 A 
 1% 
 VA 
 
 1% 
 1% 
 *A 
 
 SA 
 SA 
 
 sy 8 
 
 sy 2 
 sy 8 
 sh 
 
 va 
 
 9 
 
 9A 
 
 %A 
 
 VA 
 
 VA 
 9M 
 
 9% 
 
 9% 
 
 10^ 
 
 im 
 
 10% 
 10% 
 
 0.445 
 0.468 
 0.491 
 0.515 
 0.539 
 
 0.564 
 0.590 
 0.617 
 0.644 
 0.672 
 
 0.700 
 0.730 
 0.760 
 0.790 
 0.822 
 
 0.854 
 0.887 
 0.921 
 0.955 
 0.991 
 
 1.03 
 1.06 
 1.10 
 1.14 
 1.18 
 
 1.22 
 1.26 
 1.30 
 1.34 
 1.39 
 
 1.43 
 1.48 
 1.52 
 1.57 
 1.61 
 
 1.66 
 1.71 
 1.76 
 1.81 
 1.86 
 
 200 
 210 
 220 
 231 
 242 
 
 253 
 265 
 277 
 289 
 302 
 
 314 
 328 
 341 
 355 
 369 
 
 383 
 398 
 
 413 
 429 
 445 
 
 462 
 476 
 494 
 512 
 530 
 
 548 
 566 
 583 
 601 
 624 
 
 642 
 664 
 682 
 705 
 723 
 
 745 
 767 
 790 
 812 
 835 
 
 [31 
 
Table 4 (Concluded). Flow Over 90° V Notch Weir 
 
 Head in feet 
 "H" 
 
 Head in inches 
 approximately 
 
 Flow in cubic feet 
 per second 
 
 Flow in gallons 
 per minute 
 
 0.90 
 
 10% 
 10% 
 11% 
 11% 
 
 HM 
 
 n% 
 11% 
 11% 
 HM 
 
 11% 
 
 12 
 
 12% 
 12M 
 12% 
 
 12% 
 
 12% 
 12% 
 
 12% 
 12% 
 13% 
 
 13% 
 13% 
 13% 
 13% 
 13% 
 
 13% 
 13% 
 14% 
 14% 
 14% 
 
 14% 
 14% 
 14% 
 14% 
 14% 
 
 15 
 
 1.92 
 1.97 
 2.02 
 2.08 
 2.13 
 
 2.19 
 2.25 
 2.31 
 2.37 
 2.43 
 
 2.49 
 2.55 
 2.61 
 2.68 
 
 2.74 
 
 2.81 
 2.87 
 2.94 
 3.01 
 3.08 
 
 3.15 
 3.22 
 3.30 
 3.37 
 
 3.44 
 
 3.52 
 3.59 
 3.67 
 3.75 
 3.83 
 
 3.91 
 3.99 
 4.07 
 4.16 
 4.24 
 
 4.33 
 
 862 
 
 0.91 
 
 884 
 
 0.92 
 
 907 
 
 0.93 
 
 934 
 
 0.94 
 
 956 
 
 0.95 
 
 983 
 
 0.96 
 
 1,010 
 
 0.97 
 
 1,037 
 
 0.98 
 
 1,064 
 
 0.99 
 
 1,091 
 
 1.00 
 
 1,118 
 
 1.01 
 
 1,145 
 
 1.02 
 
 1,171 
 
 1.03 
 
 1,203 
 
 1.04 
 
 1,230 
 
 1.05 
 
 1,261 
 
 1.06 
 
 1,288 
 
 1.07 
 
 1,320 
 
 1.08 
 
 1,351 
 
 1.09 
 
 1,382 
 
 1.10 
 
 1,414 
 
 1.11 
 
 1,445 
 
 1.12 
 
 1,481 
 
 1.13 
 
 1,513 
 
 1.14 
 
 1,544 
 
 1.15 
 
 1,580 
 
 1.16 
 
 1,611 
 
 1.17 
 
 1,647 
 
 1.18 
 
 1,683 
 
 1.19 
 
 1,719 
 
 1.20 
 
 1,755 
 
 1.21. 
 
 1,791 
 
 1.22 
 
 1,827 
 
 1.23 
 
 1,867 
 
 1.24 
 
 1,903 
 
 1.25 
 
 1,943 
 
 
 
 [32] 
 
Table 5. Flow Over Cipolletti Weirs in Cubic Feet per Second 
 
 Head 
 in inches 
 approx. 
 
 We 
 We 
 W 
 We 
 We 
 
 We 
 1% 
 2J4 
 2% 
 
 2Vs 
 2V 2 
 2 5 A 
 2% 
 2Vs 
 
 3 
 
 3M 
 3^ 
 3^ 
 
 3^ 
 2% 
 3% 
 3% 
 
 4JHe 
 4Jle 
 4% 
 4% 
 
 
 Crest length (L) 
 
 1.0 foot 
 
 1.5 feet 
 
 0.107 
 0.123 
 0.140 
 0.158 
 0.177 
 
 0.195 
 0.216 
 0.237 
 0.258 
 0.280 
 
 0.302 
 0.324 
 0.349 
 0.374 
 0.397 
 
 0.423 
 0.449 
 0.475 
 0.502 
 0.529 
 
 0.557 
 0.586 
 0.615 
 0.644 
 0.675 
 
 0.705 
 0.735 
 0.767 
 0.799 
 0.832 
 
 0.866 
 0.899 
 0.932 
 0.967 
 1.00 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 Flow in cubic feet per second 
 
 0.160 
 0.185 
 0.210 
 0.237 
 0.264 
 
 0.293 
 0.322 
 0.353 
 0.384 
 
 0.417 
 
 0.450 
 0.484 
 0.519 
 0.555 
 0.591 
 
 0.628 
 0.667 
 0.705 
 0.745 
 0.785 
 
 0.827 
 0.869 
 0.911 
 0.954 
 1.00 
 
 1.04 
 1.09 
 1.13 
 1.18 
 1.23 
 
 1.28 
 1.32 
 1.37 
 1.42 
 1.47 
 
 0.214 
 0.246 
 0.280 
 0.316 
 0.352 
 
 0.390 
 0.430 
 0.470 
 0.512 
 0.555 
 
 0.599 
 0.644 
 0.691 
 0.739 
 0.786 
 
 0.836 
 0.886 
 0.937 
 0.990 
 1.04 
 
 1.10 
 1.15 
 1.21 
 1.27 
 1.32 
 
 1.38 
 1.44 
 1.50 
 1.57 
 1.63 
 
 1.69 
 1.76 
 1.82 
 1.89 
 1.95 
 
 0.321 
 0.370 
 0.421 
 0.474 
 0.528 
 
 0.586 
 0.644 
 0.705 
 0.768 
 0.832 
 
 0.898 
 
 0.966 
 
 1.04 
 
 1.11 
 
 1.18 
 
 1.25 
 1.33 
 1.40 
 1.48 
 1.56 
 
 1.64 
 1.73 
 1.81 
 1.89 
 1.98 
 
 2.07 
 2.16 
 2.25 
 2.34 
 2.43 
 
 2.53 
 2.62 
 2.72 
 2.81 
 2.91 
 
 0.429 
 0.494 
 0.562 
 0.632 
 0.706 
 
 0.782 
 0.860 
 0.941 
 1.024 
 1.110 
 
 1.20 
 1.29 
 1.38 
 1.47 
 1.57 
 
 1.67 
 1.77 
 1.87 
 1.97 
 2.08 
 
 2.19 
 2.30 
 
 2.41 
 2.52 
 2.64 
 
 2.75 
 2.87 
 2.99 
 3.11 
 3.24 
 
 3.36 
 3.49 
 3.61 
 3.74 
 3.87 
 
 For each 
 additional 
 foot of crest 
 in excess 
 of 4 ft. 
 (approx.) 
 
 0.108 
 0.124 
 0.141 
 0.159 
 0.177 
 
 0.196 
 0.216 
 0.236 
 0.257 
 0.278 
 
 0.302 
 
 0.324 
 
 0.35 
 
 0.37 
 
 0.39 
 
 0.42 
 0.44 
 0.47 
 0.49 
 0.52 
 
 0.55 
 0.57 
 0.60 
 0.62 
 0.66 
 
 0.69 
 0.71 
 0.74 
 0.78 
 0.81 
 
 0.84 
 0.87 
 0.89 
 0.93 
 0.97 
 
 Computed from Cone's formula: 
 
 0.566 Lis 
 
 3.247 LHi-« Hi-9 + 0.609 W-*. 
 
 1 + 2Li8 
 
 [33] 
 

 Table 5 {Continued). Flow Over Cipolletti Weirs 
 
 
 
 Head 
 in inches 
 approx. 
 
 Crest length (L) 
 
 For each 
 
 Head 
 in ft. 
 "H" 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 foot of crest 
 in excess 
 
 
 
 Flow in cubic feet per second 
 
 (approx.) 
 
 0.45 
 
 5^8 
 
 1.04 
 
 1.53 
 
 2.02 
 
 3.01 
 
 4.01 
 
 1.00 
 
 0.46 
 
 5V 2 
 
 1.07 
 
 1.58 
 
 2.09 
 
 3.11 
 
 4.14 
 
 1.02 
 
 0.47 
 
 5 5 A 
 
 1.11 
 
 1.63 
 
 2.16 
 
 3.21 
 
 4.28 
 
 1.06 
 
 0.48 
 
 5% 
 
 1.15 
 
 1.68 
 
 2.23 
 
 3.32 
 
 4.41 
 
 1.10 
 
 0.49 
 
 5 7 A 
 
 1.18 
 
 1.74 
 
 2.30 
 
 3.42 
 
 4.55 
 
 1.13 
 
 0.50 
 
 6 
 
 1.22 
 
 1.79 
 
 2.37 
 
 3.53 
 
 4.69 
 
 1.16 
 
 0.51 
 
 VA 
 
 1.26 
 
 1.85 
 
 2.44 
 
 3.64 
 
 4.83 
 
 1.20 
 
 0.52 
 
 6M 
 
 1.30 
 
 1.90 
 
 2.51 
 
 3.74 
 
 4.97 
 
 1.24 
 
 0.53 
 
 GVs 
 
 1.34 
 
 1.96 
 
 2.59 
 
 3.85 
 
 5.12 
 
 1.26 
 
 0.54 
 
 VA 
 
 1.38 
 
 2.02 
 
 2.66 
 
 3.96 
 
 5.26 
 
 1.30 
 
 0.55 
 
 &A 
 
 1.42 
 
 2.07 
 
 2.74 
 
 4.07 
 
 5.41 
 
 1.33 
 
 0.56 
 
 en 
 
 1.46 
 
 2.13 
 
 2.81 
 
 4.18 
 
 5.56 
 
 1.38 
 
 0.57 
 
 6% 
 
 1.50 
 
 2.19 
 
 2.89 
 
 4.30 
 
 5.71 
 
 1.41 
 
 0.58 
 
 6% 
 
 1.54 
 
 2.25 
 
 2.97 
 
 4.41 
 
 5.86 
 
 1.44 
 
 0.59 
 
 7>16 
 
 1.58 
 
 2.31 
 
 3.05 
 
 4.53 
 
 6.01 
 
 1.49 
 
 0.60 
 
 1% 
 
 1.62 
 
 2.37 
 
 3.13 
 
 4.64 
 
 6.17 
 
 1.53 
 
 0.61 
 
 IK 
 
 1.67 
 
 2.43 
 
 3.20 
 
 4.76 
 
 6.32 
 
 1.55 
 
 0.62 
 
 7Jie 
 
 1.71 
 
 2.49 
 
 3.28 
 
 4.88 
 
 6.47 
 
 1.60 
 
 0.63 
 
 1% 
 
 1.75 
 
 2.55 
 
 3.37 
 
 5.00 
 
 6.63 
 
 1.63 
 
 0.64 
 
 7% 
 
 1.80 
 
 2.62 
 
 3.45 
 
 5.12 
 
 6.79 
 
 1.67 
 
 0.65 
 
 7% 
 
 1.84 
 
 2.68 
 
 3.53 
 
 5.24 
 
 6.95 
 
 1.72 
 
 0.66 
 
 7% 
 
 1.89 
 
 2.75 
 
 3.61 
 
 5.36 
 
 7.11 
 
 1.75 
 
 0.67 
 
 SH 
 
 1.93 
 
 2.81 
 
 3.70 
 
 5.48 
 
 7.28 
 
 1.79 
 
 0.68 
 
 s% 
 
 1.98 
 
 2.87 
 
 3.79 
 
 5.61 
 
 7.44 
 
 1.83 
 
 0.69 
 
 SH 
 
 2.02 
 
 2.94 
 
 3.87 
 
 5.73 
 
 7.61 
 
 1.87 
 
 0.70 
 
 8 3 /8 
 
 2.07 
 
 3.01 
 
 3.95 
 
 5.86 
 
 7.77 
 
 1.91 
 
 0.71 
 
 sy 2 
 
 2.12 
 
 3.07 
 
 4.04 
 
 5.99 
 
 7.94 
 
 1.95 
 
 0.72 
 
 sy 8 
 
 2.16 
 
 3.14 
 
 4.13 
 
 6.12 
 
 8.11 
 
 1.99 
 
 0.73 
 
 s% 
 
 2.21 
 
 3.21 
 
 4.22 
 
 6.24 
 
 8.28 
 
 2.03 
 
 0.74 
 
 sy 8 
 
 2.26 
 
 3.28 
 
 4.31 
 
 6.38 
 
 8.45 
 
 2.08 
 
 0.75 
 
 9 
 
 2.31 
 
 3.35 
 
 4.40 
 
 6.51 
 
 8.62 
 
 2.12 
 
 0.76 
 
 93^ 
 
 2.36 
 
 3.42 
 
 4.49 
 
 6.64 
 
 8.80 
 
 2.16 
 
 0.77 
 
 9M 
 
 2.41 
 
 3.49 
 
 4.58 
 
 6.77 
 
 8.97 
 
 2.21 
 
 0.78 
 
 9^ 
 
 2.46 
 
 3.56 
 
 4.67 
 
 6.90 
 
 9.15 
 
 2.24 
 
 0.79 
 
 9^ 
 
 2.51 
 
 3.63 
 
 4.76 
 
 7.04 
 
 9.33 
 
 2.29 
 
 [34 
 
Table 5 {Continued). Flow Over Cipolletti Weirs 
 
 Head 
 in inches 
 approx. 
 
 9% 
 9% 
 9% 
 9% 
 10% 
 
 10% 
 
 10% 
 10% 
 10% 
 10% 
 
 10% 
 10% 
 11% 
 11% 
 11% 
 
 11% 
 11% 
 11% 
 11% 
 11% 
 
 12 
 
 12% 
 12% 
 12% 
 12% 
 
 12% 
 12% 
 12% 
 12% 
 13% 
 
 13% 
 13% 
 13% 
 13% 
 13% 
 
 Crest length (L) 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 Flow in cubic feet per second 
 
 2.56 
 2.61 
 2.66 
 2.71 
 2.77 
 
 2.82 
 2.87 
 2.93 
 2.98 
 3.04 
 
 3.09 
 3.15 
 3.20 
 3.26 
 3.32 
 
 3.37 
 3.43 
 3.49 
 3.55 
 3.61 
 
 3.67 
 
 3.70 
 3.77 
 3.84 
 3.92 
 3.99 
 
 4.07 
 4.14 
 4.22 
 4.29 
 4.37 
 
 4.45 
 4.53 
 4.60 
 4.68 
 4.76 
 
 4.84 
 4.92 
 5.00 
 5.09 
 5.17 
 
 5.25 
 5.33 
 5.42 
 5.50 
 5.59 
 
 5.67 
 5.76 
 5.84 
 5.93 
 6.02 
 
 6.11 
 6.20 
 6.29 
 6.37 
 6.46 
 
 4.85 
 4.95 
 5.04 
 5.14 
 5.23 
 
 5.33 
 5.43 
 5.52 
 5.62 
 5.72 
 
 5.82 
 5.92 
 6.02 
 6.13 
 6.23 
 
 6.33 
 6.44 
 6.55 
 6.64 
 6.75 
 
 6.86 
 6.96 
 7.07 
 7.18 
 7.29 
 
 7.40 
 7.51 
 7.62 
 7.73 
 
 7.84 
 
 7.96 
 8.07 
 8.18 
 8.29 
 8.41 
 
 7.18 
 7 31 
 7.45 
 7.59 
 7.73 
 
 7.87 
 8.01 
 8.15 
 8.30 
 
 8.44 
 
 8.59 
 8.73 
 8.88 
 9.03 
 9.17 
 
 9.32 
 9.48 
 9.62 
 9.78 
 9.93 
 
 10.08 
 10.24 
 10.40 
 10.55 
 10.71 
 
 10.87 
 11.03 
 11.18 
 11.35 
 11.51 
 
 11.68 
 11.84 
 12.00 
 12.16 
 12.33 
 
 9.51 
 
 9.69 
 
 9.87 
 
 10.05 
 
 10.23 
 
 10.42 
 10.60 
 10.79 
 10.98 
 11.17 
 
 11.36 
 11.55 
 11.74 
 11.94 
 12.13 
 
 12.33 
 12.53 
 12.72 
 12.92 
 13.12 
 
 13.32 
 13.53 
 13.73 
 13.94 
 14.15 
 
 14.35 
 14.56 
 14.76 
 14.98 
 15.19 
 
 15.41 
 15.62 
 15.84 
 16.04 
 16.26 
 
 For each 
 additional 
 foot of crest 
 in excess 
 of 4 ft. 
 (approx.) 
 
 2.33 
 2.38 
 2.42 
 2.46 
 2.51 
 
 2.55 
 2.60 
 2.64 
 2.69 
 2.72 
 
 2.77 
 2.82 
 2.87 
 2.91 
 2.96 
 
 3.00 
 3.05 
 3.10 
 3.14 
 3.19 
 
 3.24 
 3.29 
 3.34 
 3.38 
 3.43 
 
 3.48 
 3.53 
 3.58 
 3.63 
 3.68 
 
 3.74 
 3.79 
 3.84 
 3.88 
 3.94 
 
 [35] 
 
Table 5 {Concluded). Flow Over Cipolletti Weirs 
 
 Head 
 
 in inches, 
 
 approx. 
 
 13% 
 13% 
 14% 
 14% 
 14M 
 
 U*A 
 
 14M 
 
 14^ 
 
 15 
 
 153^ 
 15^ 
 
 15H 
 
 15^ 
 15M 
 15% 
 15% 
 16% 
 
 16% 
 16% 
 16% 
 16% 
 16% 
 
 16% 
 16% 
 17% 
 17% 
 17M 
 
 17^g 
 
 n 5 A 
 UK 
 n% 
 
 18 
 
 Crest length (L) 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 Flow in cubic feet per second 
 
 6.56 
 6.65 
 6.74 
 8.83 
 6.93 
 
 7.02 
 7.11 
 7.20 
 7.30 
 7.40 
 
 7.49 
 
 8.53 
 8.65 
 8.76 
 8.88 
 9.00 
 
 9.12 
 9.24 
 9.36 
 9.48 
 9.60 
 
 9.72 
 
 12.50 
 12.67 
 12.84 
 13.01 
 13.18 
 
 13.35 
 13.52 
 13.69 
 13.87 
 14.04 
 
 14.21 
 14.39 
 14.56 
 14.74 
 14.92 
 
 15.11 
 15.29 
 15.46 
 15.64 
 15.82 
 
 16.01 
 16.19 
 16.37 
 16.57 
 16.75 
 
 16.94 
 17.13 
 17.31 
 17.51 
 17.70 
 
 17.89 
 18.08 
 18.28 
 18.47 
 18.66 
 
 18.85 
 
 4.0 feet 
 
 16.48 
 16.70 
 16.93 
 17.15 
 17.37 
 
 17.59 
 17.81 
 18.03 
 18.27 
 18.49 
 
 18.71 
 18.95 
 19.17 
 19.41 
 19.65 
 
 19.88 
 20.12 
 20.34 
 20.58 
 20.82 
 
 21.06 
 21.29 
 21.53 
 21.78 
 22.02 
 
 22.27 
 22.51 
 22.75 
 23.01 
 23.26 
 
 23.50 
 23.75 
 24.01 
 24.26 
 24.50 
 
 24.75 
 
 [36 
 
Table 6. Flow Over Rectangular Suppressed Weirs 
 in Cubic Feet per Second* 
 
 
 Head 
 
 in 
 inches, 
 approx. 
 
 Weir height 
 
 Head, 
 in 
 feet 
 
 0.5 foot 
 
 0.75 foot 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 
 
 Flow 
 
 in cubic feet 
 
 per second per foot of weir crest 
 
 
 0.10. . 
 
 m 
 
 0.111 
 
 0.110 
 
 0.109 
 
 0.109 
 
 0.108 
 
 0.108 
 
 0.108 
 
 0.11.. 
 
 i% 
 
 0.127 
 
 0.126 
 
 0.126 
 
 0.125 
 
 0.125 
 
 0.125 
 
 0.124 
 
 0.12.. 
 
 in 
 
 0.145 
 
 0.144 
 
 0.143 
 
 0.142 
 
 0.142 
 
 0.141 
 
 0.141 
 
 0.13.. 
 
 i% 
 
 0.163 
 
 0.162 
 
 0.161 
 
 0.160 
 
 0.159 
 
 0.159 
 
 0.159 
 
 0.14. . 
 
 We 
 
 0.182 
 
 0.180 
 
 0.179 
 
 0.178 
 
 0.178 
 
 0.177 
 
 0.177 
 
 0.15. . 
 
 1% 
 
 0.202 
 
 0.200 
 
 0.199 
 
 0.197 
 
 0.197 
 
 0.196 
 
 0.196 
 
 0.16. 
 
 1% 
 
 0.223 
 
 0.220 
 
 0.219 
 
 0.217 
 
 0.216 
 
 0.216 
 
 0.215 
 
 0.17.. 
 
 2% 
 
 0.244 
 
 0.241 
 
 0.239 
 
 0.238 
 
 0.237 
 
 0.236 
 
 0.235 
 
 0.18. 
 
 2*A 
 
 0.266 
 
 0.263 
 
 0.261 
 
 0.259 
 
 0.257 
 
 0.257 
 
 0.256 
 
 0.19. 
 
 2H 
 
 0.289 
 
 0.285 
 
 0.283 
 
 0.280 
 
 0.279 
 
 0.277 
 
 0.277 
 
 0.20. . 
 
 *% 
 
 0.312 
 
 0.307 
 
 0.305 
 
 0.302 
 
 0.300 
 
 0.299 
 
 0.299 
 
 0.21. 
 
 2V 2 
 
 0.336 
 
 0.331 
 
 0.328 
 
 0.325 
 
 0.324 
 
 0.322 
 
 0.322 
 
 0.22 
 
 2Vs 
 
 0.361 
 
 0.355 
 
 0.352 
 
 0.349 
 
 0.347 
 
 0.345 
 
 0.344 
 
 0.23.. 
 
 2M 
 
 0.387 
 
 0.386 
 
 0.376 
 
 0.372 
 
 0.370 
 
 0.369 
 
 0.368 
 
 0.24. . 
 
 2Vs 
 
 0.413 
 
 0.406 
 
 0.401 
 
 0.397 
 
 0.395 
 
 0.393 
 
 0.392 
 
 0.25. 
 
 3 
 
 0.440 
 
 0.431 
 
 0.427 
 
 0.422 
 
 0.420 
 
 0.418 
 
 0.416 
 
 0.26. 
 
 3^ 
 
 0.467 
 
 0.458 
 
 0.452 
 
 0.447 
 
 0.445 
 
 0.442 
 
 0.442 
 
 0.27. 
 
 3M 
 
 0.495 
 
 0.485 
 
 0.479 
 
 0.473 
 
 0.471 
 
 0.468 
 
 0.467 
 
 0.28. 
 
 Ws 
 
 0.524 
 
 0.513 
 
 0.506 
 
 0.500 
 
 0.498 
 
 0.495 
 
 0.493 
 
 0.29. 
 
 sy 2 
 
 0.554 
 
 0.541 
 
 0.535 
 
 0.527 
 
 0.524 
 
 0.521 
 
 0.520 
 
 0.30. 
 
 &A 
 
 0.583 
 
 0.569 
 
 0.562 
 
 0.555 
 
 0.552 
 
 0.548 
 
 0.545 
 
 0.31. 
 
 3% 
 
 0.614 
 
 0.599 
 
 0.591 
 
 0.583 
 
 0.580 
 
 0.576 
 
 0.574 
 
 0.32. 
 
 3% 
 
 0.645 
 
 0.629 
 
 0.620 
 
 0.612 
 
 0.608 
 
 0.604 
 
 0.602 
 
 0.33 
 
 3% 
 
 0.677 
 
 0.659 
 
 0.650 
 
 0.641 
 
 0.637 
 
 0.633 
 
 0.631 
 
 0.34 
 
 ^A 
 
 0.709 
 
 0.690 
 
 0.681 
 
 0.670 
 
 0.666 
 
 0.662 
 
 0.660 
 
 0.35. 
 
 4^6 
 
 0.742 
 
 0.722 
 
 0.711 
 
 0.701 
 
 0.696 
 
 0.691 
 
 0.688 
 
 0.36 
 
 m 
 
 0.775 
 
 0.754 
 
 0.743 
 
 0.731 
 
 0.725 
 
 0.721 
 
 0.717 
 
 0.37 
 
 m 
 
 0.810 
 
 0.787 
 
 0.774 
 
 0.762 
 
 0.757 
 
 0.751 
 
 0.748 
 
 0.38.. 
 
 ±% 
 
 0.844 
 
 0.819 
 
 0.807 
 
 0.793 
 
 0.788 
 
 0.782 
 
 0.778 
 
 0.39. 
 
 *% 
 
 0.881 
 
 0.853 
 
 0.840 
 
 0.826 
 
 0.819 
 
 0.813 
 
 0.809 
 
 0.40. . 
 
 4% 
 
 0.916 
 
 0.888 
 
 0.873 
 
 0.858 
 
 0.851 
 
 0.844 
 
 0.840 
 
 0.41.. 
 
 4% 
 
 0.952 
 
 0.922 
 
 0.907 
 
 0.890 
 
 0.883 
 
 0.876 
 
 0.872 
 
 0.42.. 
 
 5H 
 
 0.990 
 
 0.958 
 
 0.942 
 
 0.924 
 
 0.917 
 
 0.908 
 
 0.904 
 
 0.43. 
 
 5V 8 
 
 1.03 
 
 0.994 
 
 0.976 
 
 0.958 
 
 0.950 
 
 0.941 
 
 0.937 
 
 0.44.. 
 
 5H 
 
 1.07 
 
 1.03 
 
 1.01 
 
 0.993 
 
 0.983 
 
 0.974 
 
 0.969 
 
 * Computed from the simplified form of Rehbock's formula Q = 2/3 m L v2 e h 3 '-, where m = 0.605 + 
 0.00328 h 
 
 ■ + 0.08 — and P = height of weir crest above bottom of channel of approach. 
 
 h P 
 
 [37] 
 
Table 6 (Continued). Flow Over Rectangular Suppressed Weirs 
 
 
 Head 
 
 in 
 inches, 
 approx. 
 
 Weir height 
 
 Head, 
 in 
 feet 
 
 0.5 foot 
 
 0.75 foot 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 
 
 
 
 
 
 
 
 
 
 
 Flow 
 
 in cubic feet 
 
 per second per foot of weir 
 
 crest 
 
 
 0.45.. 
 
 5Vs 
 
 1.10 
 
 1.07 
 
 1.05 
 
 1.03 
 
 1.02 
 
 1.01 
 
 1.00 
 
 0.46. 
 
 5 l A 
 
 1.14 
 
 1.10 
 
 1.08 
 
 1.06 
 
 1.05 
 
 1.04 
 
 1.04 
 
 0.47.. 
 
 5V 8 
 
 1.18 
 
 1.14 
 
 1.12 
 
 1.10 
 
 1.09 
 
 1.08 
 
 1.07 
 
 0.48. . 
 
 5M 
 
 1.22 
 
 1.18 
 
 1.16 
 
 1.13 
 
 1.12 
 
 1.11 
 
 1.10 
 
 0.49.. 
 
 5Vs 
 
 1.27 
 
 1.22 
 
 1.19 
 
 1.17 
 
 1.16 
 
 1.15 
 
 1.14 
 
 0.50. 
 
 6 
 
 1.31 
 
 1.26 
 
 1.23 
 
 1.21 
 
 1.20 
 
 1.18 
 
 1.18 
 
 0.51 
 
 6^ 
 
 1.35 
 
 1.30 
 
 1.27 
 
 1.24 
 
 1.23 
 
 1.22 
 
 1.21 
 
 0.52 
 
 6M 
 
 1.39 
 
 1.34 
 
 1.31 
 
 1.28 
 
 1.27 
 
 1.25 
 
 1.25 
 
 0.53 
 
 6^ 
 
 1.44 
 
 1.38 
 
 1.35 
 
 1.32 
 
 1.30 
 
 1.29 
 
 1.28 
 
 0.54.. 
 
 VA 
 
 1.48 
 
 1.42 
 
 1.39 
 
 1.36 
 
 1.34 
 
 1.33 
 
 1.32 
 
 0.55. 
 
 *% 
 
 1.52 
 
 1.46 
 
 1.43 
 
 1.40 
 
 1.38 
 
 1.36 
 
 1.36 
 
 0.56 
 
 G% 
 
 1.57 
 
 1.50 
 
 1.47 
 
 1.44 
 
 1.42 
 
 1.40 
 
 1.39 
 
 0.57.. 
 
 G% 
 
 1.61 
 
 1.54 
 
 1.51 
 
 1.48 
 
 1.46 
 
 1.44 
 
 1.43 
 
 0.58 . 
 
 6% 
 
 1.66 
 
 1.59 
 
 1.55 
 
 1.52 
 
 1.50 
 
 1.48 
 
 1.47 
 
 0.59. 
 
 7>1e 
 
 1.71 
 
 1.63 
 
 1.60 
 
 1.56 
 
 1.54 
 
 1.52 
 
 1.51 
 
 0.60. 
 
 7% 
 
 1.76 
 
 1.68 
 
 1.64 
 
 1.60 
 
 1.58 
 
 1.56 
 
 1.55 
 
 0.61. 
 
 7^ 
 
 1.80 
 
 1.72 
 
 1.68 
 
 1.64 
 
 1.62 
 
 1.59 
 
 1.58 
 
 0.62 
 
 7^6 
 
 1.85 
 
 1.77 
 
 1.72 
 
 1.68 
 
 1.66 
 
 1.63 
 
 1.62 
 
 0.63 
 
 7% 
 
 1.90 
 
 1.81 
 
 1.77 
 
 1.72 
 
 1.70 
 
 1.68 
 
 1.67 
 
 0.64. 
 
 7% 
 
 1.95 
 
 1.86 
 
 1.81 
 
 1.76 
 
 1.74 
 
 1.72 
 
 1.71 
 
 0.65 
 
 7% 
 
 2.00 
 
 1.90 
 
 1.86 
 
 1.81 
 
 1.78 
 
 1.76 
 
 1.75 
 
 0.66 
 
 7% 
 
 2.05 
 
 1.95 
 
 1.90 
 
 1.85 
 
 1.82 
 
 1.80 
 
 1.79 
 
 0.67. 
 
 W 
 
 2.10 
 
 2.00 
 
 1.95 
 
 1.90 
 
 1.87 
 
 1.84 
 
 1.83 
 
 0.68 
 
 sy 8 
 
 2.15 
 
 2.05 
 
 1.99 
 
 1.94 
 
 1.91 
 
 1.88 
 
 1.87 
 
 0.69. 
 
 SH 
 
 2.21 
 
 2.09 
 
 2.04 
 
 1.98 
 
 1.95 
 
 1.93 
 
 1.91 
 
 0.70. 
 
 SH 
 
 2.26 
 
 2.14 
 
 2.08 
 
 2.03 
 
 2.00 
 
 1.97 
 
 1.95 
 
 0.71.. 
 
 sy 2 
 
 2.31 
 
 2.19 
 
 2.13 
 
 2.07 
 
 2.04 
 
 2.01 
 
 2.00 
 
 0.72. 
 
 Ws 
 
 2.37 
 
 2.24 
 
 2.18 
 
 2.12 
 
 2.08 
 
 2.05 
 
 2.04 
 
 0.73. 
 
 8% 
 
 2.42 
 
 2.29 
 
 2.23 
 
 2.16 
 
 2.13 
 
 2.10 
 
 2.08 
 
 0.74. . 
 
 sy 8 
 
 2.48 
 
 2.34 
 
 2.28 
 
 2.21 
 
 2.18 
 
 2.14 
 
 2.12 
 
 0.75. 
 
 9 
 
 2.53 
 
 2.39 
 
 2.32 
 
 2.25 
 
 2.22 
 
 2.18 
 
 2.17 
 
 0.76. 
 
 9^ 
 
 2.59 
 
 2.45 
 
 2.37 
 
 2.30 
 
 2.27 
 
 2.23 
 
 2.21 
 
 0.77.. 
 
 9M 
 
 2.65 
 
 2.50 
 
 2.43 
 
 2.35 
 
 2.31 
 
 2.27 
 
 2.26 
 
 0.78. 
 
 9^ 
 
 2.70 
 
 2.55 
 
 2.48 
 
 2.40 
 
 2.36 
 
 2.32 
 
 2.30 
 
 0.79. 
 
 9^ 
 
 2.76 
 
 2.60 
 
 2.52 
 
 2.45 
 
 2.41 
 
 2.37 
 
 2.35 
 
 [38] 
 

 Table 6 {Continued). Flow Over Rectangular Suppressed Weirs 
 
 
 Head 
 
 in 
 inches, 
 approx. 
 
 Weir height 
 
 Head, 
 in 
 feet 
 
 0.5 foot 
 
 0.75 foot 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 
 
 
 
 
 
 
 
 
 
 Flow in cubic feet 
 
 per second per foot of weir 
 
 crest 
 
 
 0.80.. 
 
 9^ 
 
 2.82 
 
 2.66 
 
 2.58 
 
 2.49 
 
 2.45 
 
 2.41 
 
 2.39 
 
 0.81.. 
 
 9% 
 
 2.88 
 
 2.71 
 
 2.63 
 
 2.54 
 
 2.50 
 
 2.46 
 
 2.44 
 
 0.82.. 
 
 9% 
 
 2.94 
 
 2.76 
 
 2.68 
 
 2.59 
 
 2.55 
 
 2.51 
 
 2.48 
 
 0.83. 
 
 9% 
 
 3.00 
 
 2.82 
 
 2.73 
 
 2.64 
 
 2.60 
 
 2.55 
 
 2.53 
 
 0.84.. 
 
 10% 
 
 3.06 
 
 2.87 
 
 2.78 
 
 2.69 
 
 2.64 
 
 2.60 
 
 2.58 
 
 0.85.. 
 
 10% 
 
 3.12 
 
 2.93 
 
 2.84 
 
 2.74 
 
 2.69 
 
 2.65 
 
 2.62 
 
 0.86. 
 
 iojk 
 
 3.18 
 
 2.99 
 
 2.89 
 
 2.79 
 
 2.74 
 
 2.69 
 
 2.67 
 
 0.87.. 
 
 10% 
 
 3.25 
 
 3.04 
 
 2.94 
 
 2.84 
 
 2.80 
 
 2.74 
 
 2.72 
 
 0.88. 
 
 10% 
 
 3.31 
 
 3.10 
 
 3.00 
 
 2.90 
 
 2.84 
 
 2.79 
 
 2.76 
 
 0.89.. 
 
 10% 
 
 3.37 
 
 3.16 
 
 3.05 
 
 2.95 
 
 2.89 
 
 2.84 
 
 2.81 
 
 0.90. 
 
 10% 
 
 3.43 
 
 3.22 
 
 3.11 
 
 3.00 
 
 2.95 
 
 2.89 
 
 2.86 
 
 0.91.. 
 
 10% 
 
 3.50 
 
 3.27 
 
 3.16 
 
 3.05 
 
 2.99 
 
 2.94 
 
 2.91 
 
 0.92. 
 
 11% 
 
 3.57 
 
 3.34 
 
 3.22 
 
 3.11 
 
 3.04 
 
 2.99 
 
 2.96 
 
 0.93 
 
 11% 
 
 3.63 
 
 3.40 
 
 3.28 
 
 3.16 
 
 3.10 
 
 3.04 
 
 3.01 
 
 0.94. 
 
 HM 
 
 3.70 
 
 3.46 
 
 3.33 
 
 3.21 
 
 3.15 
 
 3.09 
 
 3.06 
 
 0.95.. 
 
 liVs 
 
 3.76 
 
 3.52 
 
 3.39 
 
 3.26 
 
 3.20 
 
 3.14 
 
 3.11 
 
 0.96.. 
 
 UK 
 
 3.83 
 
 3.58 
 
 3.45 
 
 3.32 
 
 3.26 
 
 3.19 
 
 3.16 
 
 0.97. 
 
 n^ 
 
 3.90 
 
 3.64 
 
 3.51 
 
 3.37 
 
 3.31 
 
 3.24 
 
 3.21 
 
 0.98.. 
 
 nM 
 
 3.97 
 
 3.70 
 
 3.57 
 
 3.42 
 
 3.36 
 
 3.29 
 
 3.26 
 
 0.99. . 
 
 UK 
 
 4.04 
 
 3.76 
 
 3.62 
 
 3.48 
 
 3.41 
 
 3.35 
 
 3.31 
 
 1.00. . 
 
 12 
 
 4.11 
 
 3.82 
 
 3.68 
 
 3.54 
 
 3.47 
 
 3.40 
 
 3.36 
 
 1.01.. 
 
 lZVs 
 
 
 3.89 
 
 3.74 
 
 3.59 
 
 3.52 
 
 3.45 
 
 3.41 
 
 1.02.. 
 
 12M 
 
 
 3.95 
 
 3.80 
 
 3.65 
 
 3.58 
 
 3.50 
 
 3.47 
 
 1.03.. 
 
 12^ 
 
 
 4.01 
 
 3.86 
 
 3.71 
 
 3.63 
 
 3.56 
 
 3.52 
 
 1.04.. 
 
 12K 
 
 
 4.08 
 
 3.93 
 
 3.77 
 
 3.69 
 
 3.61 
 
 3.57 
 
 1.05.. 
 
 12^ 
 
 
 4.14 
 
 3.98 
 
 3.82 
 
 3.74 
 
 3.66 
 
 3.62 
 
 1.06.. 
 
 12M 
 
 
 4.21 
 
 4.04 
 
 3.88 
 
 3.80 
 
 3.71 
 
 3.67 
 
 1.07. . 
 
 12% 
 
 
 4.27 
 
 4.11 
 
 3.94 
 
 3.85 
 
 3.77 
 
 3.73 
 
 1.08.. 
 
 12% 
 
 
 4.34 
 
 4.17 
 
 4.00 
 
 3.91 
 
 3.82 
 
 3.78 
 
 1.09.. 
 
 13% 
 
 
 4.41 
 
 4.24 
 
 4.05 
 
 3.97 
 
 3.88 
 
 3.83 
 
 1.10.. 
 
 13% 
 
 
 4.48 
 
 4.30 
 
 4.12 
 
 4.02 
 
 3.93 
 
 3.89 
 
 1.11.. 
 
 13% 
 
 
 4.54 
 
 4.36 
 
 4.17 
 
 4.09 
 
 3.99 
 
 3.94 
 
 1.12. . 
 
 13% 
 
 
 4.61 
 
 4.42 
 
 4.23 
 
 4.14 
 
 4.04 
 
 3.99 
 
 1.13.. 
 
 13% 
 
 
 4.68 
 
 4.49 
 
 4.29 
 
 4.19 
 
 4.10 
 
 4.05 
 
 1.14.. 
 
 13% 
 
 
 4.75 
 
 4.55 
 
 4.36 
 
 4.26 
 
 4.15 
 
 4.11 
 
 [39] 
 

 Table 6 {Concluded). Flow Over Rectangu 
 
 lar Suppressed Weirs 
 
 
 Head 
 
 in 
 inches, 
 approx. 
 
 Weir height 
 
 Head, 
 in 
 feet 
 
 0.5 foot 
 
 0.75 foot 
 
 1.0 foot 
 
 1.5 feet 
 
 2.0 feet 
 
 3.0 feet 
 
 4.0 feet 
 
 
 
 
 
 
 Flow in cubic feet per second per foot of weir crest 
 
 
 1.15.. 
 
 13% 
 
 
 4.82 
 
 4.62 
 
 4.41 
 
 4.31 
 
 4.21 
 
 4.16 
 
 1.16.. 
 
 13% 
 
 
 4.89 
 
 4.68 
 
 4.47 
 
 4.37 
 
 4.27 
 
 4.22 
 
 1.17.. 
 
 14% 
 
 
 4.96 
 
 4.75 
 
 4.54 
 
 4.44 
 
 4.33 
 
 4.27 
 
 1.18.. 
 
 14% 
 
 
 5.03 
 
 4.82 
 
 4.60 
 
 4.49 
 
 4.38 
 
 4.33 
 
 1.19.. 
 
 14M 
 
 
 5.10 
 
 4.88 
 
 4.67 
 
 4.55 
 
 4.44 
 
 4.39 
 
 1.20. . 
 
 14% 
 
 
 5.17 
 
 4.95 
 
 4.72 
 
 4.61 
 
 4.50 
 
 4.44 
 
 1.21.. 
 
 14H 
 
 
 5.25 
 
 5.02 
 
 4.79 
 
 4.67 
 
 4.56 
 
 4.50 
 
 1.22 
 
 W* 
 
 
 5.32 
 
 5.09 
 
 4.85 
 
 4.73 
 
 4.61 
 
 4.56 
 
 1.23.. 
 
 14M 
 
 
 5.39 
 
 5.16 
 
 4.92 
 
 4.79 
 
 4.68 
 
 4.61 
 
 1.24. . 
 
 14% 
 
 
 5.47 
 
 5.22 
 
 4.98 
 
 4.88 
 
 4.73 
 
 4.67 
 
 1.25.. 
 
 15 
 
 
 5.54 
 
 5.29 
 
 5.05 
 
 4.92 
 
 4.79 
 
 4.73 
 
 1.26. . 
 
 15% 
 
 
 
 5.36 
 
 5.10 
 
 4.98 
 
 4.85 
 
 4.79 
 
 1.27.. 
 
 15K 
 
 
 
 5.43 
 
 5.17 
 
 5.04 
 
 4.91 
 
 4.84 
 
 1.28.. 
 
 15% 
 
 
 
 5.51 
 
 5.24 
 
 5.10 
 
 4.97 
 
 4.90 
 
 1.29. 
 
 15% 
 
 
 
 5.57 
 
 5.30 
 
 5.16 
 
 5.03 
 
 4.96 
 
 1.30.. 
 
 15% 
 
 
 
 5.64 
 
 5.36 
 
 5.23 
 
 5.09 
 
 5.02 
 
 1.31.. 
 
 15^ 
 
 
 
 5.72 
 
 5.44 
 
 5.29 
 
 5.16 
 
 5.08 
 
 1.32.. 
 
 15% 
 
 
 
 5.79 
 
 5.50 
 
 5.36 
 
 5.22 
 
 5.14 
 
 1.33. 
 
 15% 
 
 
 
 5.86 
 
 5.57 
 
 5.42 
 
 5.28 
 
 5.20 
 
 1.34. . 
 
 16% 
 
 
 
 5.93 
 
 5.63 
 
 5.48 
 
 5.33 
 
 5.26 
 
 1.35. . 
 
 16% 
 
 
 
 6.01 
 
 5.71 
 
 5.56 
 
 5.40 
 
 5.32 
 
 1.36. 
 
 16% 
 
 
 
 6.08 
 
 5.77 
 
 5.62 
 
 5.46 
 
 5.38 
 
 1.37.. 
 
 16% 
 
 
 
 6.15 
 
 5.84 
 
 5.68 
 
 5.52 
 
 5.45 
 
 1.38. 
 
 16% 
 
 
 
 6.22 
 
 5.90 
 
 5.75 
 
 5.58 
 
 5.51 
 
 1.39. 
 
 16% 
 
 
 
 6.30 
 
 5.98 
 
 5.81 
 
 5.65 
 
 5.57 
 
 1.40. . 
 
 16% 
 
 
 
 6.38 
 
 6.04 
 
 5.87 
 
 5.71 
 
 5.62 
 
 1.41.. 
 
 16% 
 
 
 
 6.46 
 
 6.12 
 
 5.95 
 
 5.78 
 
 5.69 
 
 1.42.. 
 
 17% 
 
 
 
 6.52 
 
 6.18 
 
 6.01 
 
 5.84 
 
 5.75 
 
 1.43.. 
 
 17% 
 
 
 
 6.60 
 
 6.26 
 
 6.08 
 
 5.91 
 
 5.82 
 
 1.44. . 
 
 17% 
 
 
 
 6.68 
 
 6.32 
 
 6.15 
 
 5.97 
 
 5.88 
 
 1.45.. 
 
 17% 
 
 
 
 6.76 
 
 6.40 
 
 6.21 
 
 6.03 
 
 5.94 
 
 1.46.. 
 
 17% 
 
 
 
 6.84 
 
 6.46 
 
 6.28 
 
 6.09 
 
 6.00 
 
 1.47.. 
 
 17% 
 
 
 
 6.91 
 
 6.53 
 
 6.35 
 
 6.17 
 
 6.06 
 
 1.48 
 
 17K 
 
 
 
 6.99 
 
 6.60 
 
 6.41 
 
 6.23 
 
 6.12 
 
 1.49.. 
 
 17% 
 
 
 
 7.07 
 
 6.68 
 
 6.49 
 
 6.29 
 
 6.20 
 
 1.50. . 
 
 18 
 
 
 
 7.15 
 
 6.75 
 
 6.56 
 
 6.36 
 
 6.26 
 
 [40] 
 
Table 7. Flow Through Orifices in Cubic Feet per Second 
 
 Head, 
 H, 
 in 
 
 Head, 
 
 in 
 inches, 
 
 Cross-sectional area of orifice, A 
 
 0.25 sq. ft. 
 
 0.333 sq. ft. 
 
 0.50 sq. ft. 
 
 0.75 sq. ft. 
 
 1.00 sq. ft. 
 
 1.50 sq. ft. 
 
 2.00 sq. ft. 
 
 feet 
 
 approx. 
 
 
 
 
 
 
 
 
 
 
 
 Flow in 
 
 cubic feet per second 
 
 
 
 0.01.. 
 
 Vs 
 
 0.122 
 
 0.163 
 
 0.245 
 
 0.367 
 
 0.489 
 
 0.73 
 
 0.98 
 
 0.02 
 
 X 
 
 0.173 
 
 0.230 
 
 0.346 
 
 0.518 
 
 0.691 
 
 1.04 
 
 1.38 
 
 0.03.. 
 
 H 
 
 0.212 
 
 0.282 
 
 0.424 
 
 0.635 
 
 0.847 
 
 1.27 
 
 1.69 
 
 0.04. 
 
 l A 
 
 0.245 
 
 0.326 
 
 0.489 
 
 0.734 
 
 0.978 
 
 1.47 
 
 1.96 
 
 0.05 
 
 % 
 
 0.273 
 
 0.364 
 
 0.547 
 
 0.820 
 
 1.09 
 
 1.64 
 
 2.19 
 
 0.06.. 
 
 % 
 
 0.300 
 
 0.399 
 
 0.599 
 
 0.899 
 
 1.20 
 
 1.80 
 
 2.40 
 
 0.07.. 
 
 % 
 
 0.324 
 
 0.431 
 
 0.647 
 
 0.971 
 
 1.29 
 
 1.94 
 
 2.59 
 
 0.08.. 
 
 % 
 
 0.346 
 
 0.461 
 
 0.691 
 
 1.04 
 
 1.38 
 
 2.07 
 
 2.77 
 
 0.09.. 
 
 1% 
 
 0.367 
 
 0.489 
 
 0.734 
 
 1.10 
 
 1.47 
 
 2.20 
 
 2.94 
 
 0.10. 
 
 1% 
 
 0.387 
 
 0.518 
 
 0.773 
 
 1.16 
 
 1.56 
 
 2.32 
 
 3.09 
 
 0.11.. 
 
 1% 
 
 0.406 
 
 0.540 
 
 0.811 
 
 1.22 
 
 1.62 
 
 2.43 
 
 3.24 
 
 0.12.. 
 
 i 7 A 
 
 0.424 
 
 0.564 
 
 0.847 
 
 1.27 
 
 1.69 
 
 2.54 
 
 3.39 
 
 0.13.. 
 
 1% 
 
 0.441 
 
 0.587 
 
 0.882 
 
 1.32 
 
 1.76 
 
 2.65 
 
 3.53 
 
 0.14.. 
 
 1% 
 
 0.458 
 
 0.609 
 
 0.915 
 
 1.37 
 
 1.83 
 
 2.75 
 
 3.66 
 
 0.15.. 
 
 1% 
 
 0.474 
 
 0.631 
 
 0.947 
 
 1.42 
 
 1.90 
 
 2.84 
 
 3.79 
 
 0.16.. 
 
 1% 
 
 0.489 
 
 0.651 
 
 0.978 
 
 1.47 
 
 1.96 
 
 2.93 
 
 3.91 
 
 0.17. . 
 
 2H 
 
 0.504 
 
 0.671 
 
 1.01 
 
 1.51 
 
 2.02 
 
 3.02 
 
 4.03 
 
 0.18.. 
 
 2% 
 
 0.519 
 
 0.691 
 
 1.04 
 
 1.56 
 
 2.08 
 
 3.11 
 
 4.15 
 
 0.19.. 
 
 2H 
 
 0.533 
 
 0.710 
 
 1.07 
 
 1.60 
 
 2.13 
 
 3.20 
 
 4.26 
 
 0.20. 
 
 2% 
 
 0.547 
 
 0.729 
 
 1.09 
 
 1.64 
 
 2.19 
 
 3.28 
 
 4.38 
 
 0.21.. 
 
 2V 2 
 
 0.561 
 
 0.746 
 
 1.12 
 
 1.68 
 
 2.24 
 
 3.36 
 
 4.48 
 
 0.22.. 
 
 2% 
 
 0.574 
 
 0.765 
 
 1.15 
 
 1.72 
 
 2.30 
 
 3.46 
 
 4.59 
 
 0.23.. 
 
 2% 
 
 0.587 
 
 0.781 
 
 1.17 
 
 1.76 
 
 2.35 
 
 3.52 
 
 4.69 
 
 0.24.. 
 
 2% 
 
 0.600 
 
 0.798 
 
 1.20 
 
 1.80 
 
 2.40 
 
 3.60 
 
 4.79 
 
 0.25.. 
 
 3 
 
 0.612 
 
 0.815 
 
 1.22 
 
 1.83 
 
 2.45 
 
 3.67 
 
 4.89 
 
 0.26.. 
 
 33^ 
 
 0.624 
 
 0.831 
 
 1.25 
 
 1.87 
 
 2.49 
 
 3.74 
 
 4.99 
 
 0.27.. 
 
 3M 
 
 0.636 
 
 0.846 
 
 1.27 
 
 1.91 
 
 2.54 
 
 3.81 
 
 5.08 
 
 0.28.. 
 
 Ws 
 
 0.646 
 
 0.862 
 
 1.29 
 
 1.94 
 
 2.59 
 
 3.88 
 
 5.18 
 
 0.29.. 
 
 SV2 
 
 0.659 
 
 0.878 
 
 1.32 
 
 1.98 
 
 2.64 
 
 3.96 
 
 5.28 
 
 0.30. . 
 
 sy 8 
 
 0.670 
 
 0.892 
 
 1.34 
 
 2.01 
 
 2.68 
 
 4.02 
 
 5.36 
 
 0.31.. 
 
 3% 
 
 0.681 
 
 0.908 
 
 1.36 
 
 2.05 
 
 2.73 
 
 4.09 
 
 5.45 
 
 0.32.. 
 
 3% 
 
 0.692 
 
 0.920 
 
 1.38 
 
 2.07 
 
 2.76 
 
 4.15 
 
 5.53 
 
 0.33.. 
 
 3% 
 
 0.703 
 
 0.936 
 
 1.41 
 
 2.11 
 
 2.81 
 
 4.22 
 
 5.62 
 
 0.34. . 
 
 4^ 
 
 0.713 
 
 0.950 
 
 1.43 
 
 2.14 
 
 2.85 
 
 4.28 
 
 5.70 
 
 0.35. 
 
 4% 
 
 0.724 
 
 0.963 
 
 1.45 
 
 2.17 
 
 2.89 
 
 4.34 
 
 5.78 
 
 0.36.. 
 
 4^ 
 
 0.734 
 
 0.976 
 
 1.47 
 
 2.20 
 
 2.93 
 
 4.40 
 
 5.87 
 
 0.37.. 
 
 4% 
 
 0.745 
 
 0.991 
 
 1.49 
 
 2.23 
 
 2.98 
 
 4.46 
 
 5.95 
 
 0.38. . 
 
 4% 
 
 0.754 
 
 1.00 
 
 1.51 
 
 2.26 
 
 3.02 
 
 4.52 
 
 6.03 
 
 0.39. 
 
 4% 
 
 0.764 
 
 1.02 
 
 1.53 
 
 2.29 
 
 3.05 
 
 4.58 
 
 6.11 
 
 0.40.. 
 
 4% 
 
 0.774 
 
 1.03 
 
 1.55 
 
 2.32 
 
 3.09 
 
 4.64 
 
 6.19 
 
 
 omputed 
 
 from the forrr 
 
 iula Q = 0.61 
 
 
 
 
 
 
 * c 
 
 A V2gH. 
 
 
 [41] 
 
Table 7 {Continued). Flow Through Orifices 
 
 Head, 
 
 Head, 
 
 Cross-sectional area of orifice, A 
 
 
 
 
 
 
 
 
 H, 
 
 in 
 
 in 
 
 inches, 
 
 0.25 sq. ft. 
 
 0.333 sq. ft. 
 
 0.50 sq. ft. 
 
 0.75 sq. ft. 
 
 1.00 sq. ft. 
 
 1.50 sq. ft. 
 
 2.00 sq. ft. 
 
 feet 
 
 approx. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Flow in 
 
 cubic feet per 
 
 second 
 
 
 
 0.41.. 
 
 4% 
 
 0.783 
 
 1.04 
 
 1.57 
 
 2.35 
 
 3.13 
 
 4.70 
 
 6.27 
 
 0.42.. 
 
 5% 
 
 0.792 
 
 1.06 
 
 1.59 
 
 2.38 
 
 3.17 
 
 4.75 
 
 6.34 
 
 0.43.. 
 
 5% 
 
 0.802 
 
 1.07 
 
 1.60 
 
 2.41 
 
 3.21 
 
 4.81 
 
 6.42 
 
 0.44. . 
 
 5M 
 
 0.811 
 
 1.08 
 
 1.62 
 
 2.43 
 
 3.24 
 
 4.87 
 
 6.49 
 
 0.45.. 
 
 5Vs 
 
 0.820 
 
 1.09 
 
 1.64 
 
 2.46 
 
 3.28 
 
 4.92 
 
 6.56 
 
 0.46 . 
 
 5V 2 
 
 0.829 
 
 1.10 
 
 1.66 
 
 2.49 
 
 3.32 
 
 4.98 
 
 6.64 
 
 0.47.. 
 
 5 5 A 
 
 0.839 
 
 1.12 
 
 1.68 
 
 2.52 
 
 3.36 
 
 5.04 
 
 6.71 
 
 0.48.. 
 
 5% 
 
 0.847 
 
 1.13 
 
 1.70 
 
 2.54 
 
 3.39 
 
 5.08 
 
 6.78 
 
 0.49.. 
 
 5V 8 
 
 0.856 
 
 1.14 
 
 1.71 
 
 2.57 
 
 3.42 
 
 5.14 
 
 6.85 
 
 0.50.. 
 
 6 
 
 0.865 
 
 1.15 
 
 1.73 
 
 2.59 
 
 3.46 
 
 5.19 
 
 6.92 
 
 0.51.. 
 
 6Vs 
 
 0.873 
 
 1.16 
 
 1.75 
 
 2.62 
 
 3.49 
 
 5.24 
 
 6.99 
 
 0.52.. 
 
 6M 
 
 0.882 
 
 1.17 
 
 1.76 
 
 2.65 
 
 3.53 
 
 5.29 
 
 7.05 
 
 0.53.. 
 
 6^ 
 
 0.890 
 
 1.19 
 
 1.78 
 
 2.67 
 
 3.56 
 
 5.34 
 
 7.12 
 
 0.54.. 
 
 6^ 
 
 0.898 
 
 1.20 
 
 1.80 
 
 2.70 
 
 3.59 
 
 5.39 
 
 7.19 
 
 0.55.. 
 
 G 5 A 
 
 0.907 
 
 1.21 
 
 1.81 
 
 2.72 
 
 3.63 
 
 5.44 
 
 7.25 
 
 0.56.. 
 
 G% 
 
 0.915 
 
 1.22 
 
 1.83 
 
 2.75 
 
 3.66 
 
 5.49 
 
 7.32 
 
 0.57.. 
 
 6%. 
 
 0.923 
 
 1.23 
 
 1.85 
 
 2.77 
 
 3.69 
 
 5.54 
 
 7.38 
 
 0.58.. 
 
 &% 
 
 0.931 
 
 1.24 
 
 1.86 
 
 2.79 
 
 3.73 
 
 5.59 
 
 7.45 
 
 0.59.. 
 
 1% 
 
 0.939 
 
 1.25 
 
 1.88 
 
 2.82 
 
 3.76 
 
 5.64 
 
 7.51 
 
 0.60. 
 
 7% 
 
 C.947 
 
 1.26 
 
 1.90 
 
 2.84 
 
 3.79 
 
 5.68 
 
 7.58 
 
 0.61.. 
 
 7>*6 
 
 0.955 
 
 1.27 
 
 1.91 
 
 2.87 
 
 3.82 
 
 5.73 
 
 7.64 
 
 0.62.. 
 
 7^6 
 
 0.963 
 
 1.28 
 
 1.93 
 
 2.89 
 
 3.85 
 
 5.78 
 
 7.70 
 
 0.63.. 
 
 7% 
 
 0.971 
 
 1.29 
 
 1.94 
 
 2.91 
 
 3.88 
 
 5.82 
 
 7.76 
 
 0.64.. 
 
 7% 
 
 0.978 
 
 1.30 
 
 1.96 
 
 2.93 
 
 3.91 
 
 5.87 
 
 7.82 
 
 0.65.. 
 
 7% 
 
 0.986 
 
 1.31 
 
 1.97 
 
 2.96 
 
 3.94 
 
 5.92 
 
 7.89 
 
 0.66.. 
 
 7% 
 
 0.993 
 
 1.32 
 
 1.99 
 
 2.98 
 
 3.97 
 
 5.96 
 
 7.95 
 
 0.67.. 
 
 8^ 
 
 1.00 
 
 1.33 
 
 2.00 
 
 3.00 
 
 4.00 
 
 6.01 
 
 8.01 
 
 0.68.. 
 
 8^6 
 
 1.01 
 
 1.34 
 
 2.02 
 
 3.02 
 
 4.03 
 
 6.05 
 
 8.06 
 
 0.69.. 
 
 8M 
 
 1.02 
 
 1.35 
 
 2.03 
 
 3.05 
 
 4.06 
 
 6.10 
 
 8.13 
 
 0.70.. 
 
 8^ 
 
 1.02 
 
 1.36 
 
 2.05 
 
 3.07 
 
 4.09 
 
 6.14 
 
 8.18 
 
 0.71.. 
 
 sy 2 
 
 1.03 
 
 1.37 
 
 2.06 
 
 3.09 
 
 4.12 
 
 6.19 
 
 8.25 
 
 0.72 . 
 
 sy 8 
 
 1.04 
 
 1.38 
 
 2.08 
 
 3.11 
 
 4.15 
 
 6.23 
 
 8.30 
 
 0.73 
 
 s% 
 
 1.05 
 
 1.39 
 
 2.09 
 
 3.14 
 
 4.18 
 
 6.27 
 
 8.36 
 
 0.74.. 
 
 sy s 
 
 1.05 
 
 1.40 
 
 2.10 
 
 3.16 
 
 4.21 
 
 6.31 
 
 8.42 
 
 0.75.. 
 
 9 
 
 1.06 
 
 1.41 
 
 2.12 
 
 3.18 
 
 4.24 
 
 6.36 
 
 8.48 
 
 0.76.. 
 
 9K 
 
 1.07 
 
 1.42 
 
 2.13 
 
 3.20 
 
 4.26 
 
 6.40 
 
 8.53 
 
 0.77.. 
 
 9M 
 
 1.07 
 
 1.43 
 
 2.15 
 
 3.22 
 
 4.29 
 
 6.43 
 
 8.58 
 
 0.78.. 
 
 9^ 
 
 1.08 
 
 1.44 
 
 2.16 
 
 3.24 
 
 4.32 
 
 6.48 
 
 8.64 
 
 0.79 
 
 9H 
 
 1.09 
 
 1.45 
 
 2.17 
 
 3.26 
 
 4.35 
 
 6.52 
 
 8.70 
 
 0.80 
 
 9^ 
 
 1.09 
 
 1.46 
 
 2.19 
 
 3.28 
 
 4.38 
 
 6.56 
 
 8.75 
 
 [42 
 
Table 8 
 
 * 
 
<N 00 CO <35 CO 
 CD 00 rH CO CO 
 ■^ "tf lO id iri 
 
 — 
 
 C 
 
 o 
 
 u 
 
 o 
 
 i. 
 O 
 
 a 
 
 00ON woo 
 q co in t- as 
 
 <N <N CN CO CO COCOCO"^^ 
 
 <N CD 
 iri iri 
 
 OH I 
 
 w t- » 
 
 <N <N <N <N <N (NCOCOCOCO 
 
 3 
 U 
 
 co co t- oo o 
 
 CN CO "* in CO 
 
 rH r-i <N <N <N <N <N <N <N <N 
 
 CO <X> 
 
 O rH 
 
 CO CO 
 
 t"INO00 
 C5 O H N N 
 
 6 ri rl H H 
 
 t- CD in 'tf CO 
 CO "tf m CO t- 
 
 <N <N <N (N <N 
 00 OJ OH N 
 rH rH CN* <N CN* 
 
 o o o o o 
 
 wooo^t- 
 
 HHNNN 
 
 doddd 
 
 O *tf 00 <N CO 
 
 CO CO CO ^ ^ 
 
 d d d d d 
 
 o o o o o 
 
 HtfiOlOO 
 
 t— c- oo oo a 
 
 dddoo 
 
 ^ CD ^ CJ ^ 
 
 q q q q th 
 
 O O rH rH rH 
 
 rH <N -tf CD 00 
 rH rH rH i-l iH 
 
 doddd 
 
 O CO CD Oi <N 
 CN (N (N <M CO 
 
 d d d d d 
 
 o o o o o 
 
 o o o o o 
 
 o ^ 
 
 00 00* 
 
 d d d d d do 
 
 as o (N ^ m 
 
 O rH rH rH rH 
 
 doddd 
 
 o o o o o 
 
 o o o o o 
 
 o o o o o 
 
 o o o o o 
 
 m co t> oo o 
 o o o o o 
 d d d d d 
 
 OH (N ^ W 
 H iH tH tH r-i 
 
 doddd 
 
 o o o o o 
 
 o o o o o 
 
 Ci H 
 
 CO "*, 
 
 doddd do" 
 
 oo 
 
 
 
 00 CO t> <N t- 
 
 C3 CO CO *tf* ^* 
 
 o o o o o 
 
 d d d d d 
 
 CO oo ^ o CD 
 
 m m co t- i> 
 
 o o o o o 
 
 d d d d d 
 
 NO ON05 
 00 00 O) o O 
 
 O O O rH rH 
 
 doddd 
 
 o o o o o 
 
 ^NOfllt- 
 
 m co t- t- oo 
 
 o o o o o 
 
 co m 
 a o 
 
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PAGE 
 
 Methods of Measuring Water 3 
 
 Direct Methods 3 
 
 Collecting water in a container of known volume 3 
 
 Measuring the change in the water level 3 
 
 Direct volumetric measurements 4 
 
 Tilt bucket 4 
 
 Velocity-Area Methods 5 
 
 Float method 5 
 
 Current meter method 6 
 
 Tracer methods 8 
 
 Trajectory method 8 
 
 Pitot tube method 10 
 
 Slotted tube method 12 
 
 Methods Employing a Formed Constriction 13 
 
 Weirs 13 
 
 Orifices 16 
 
 Commercial head-gates 16 
 
 Parshall flume 16 
 
 Miscellaneous devices 19 
 
 Units of Water Measurements 22 
 
 List of Equivalents 23 
 
 Tables 25 
 
 In order that the information in our publications may be more intelligible / it is sometimes 
 necessary to use trade names of products and equipment rather than complicated descriptive or 
 chemical identifications. In so doing, it is unavoidable in some cases that similar products which 
 are on the market under other trade names may not be cited. No endorsement of named prod- 
 ucts is intended nor is criticism implied of similar products which are not mentioned. 
 
 Co-operative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United Stotej Department of Agriculture 
 co-operating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1914. George B. Alcorn, Director, California Agricultural Extension Service. 
 
 25m-l,'59(6534)JF 
 
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