STATE COMMITTEE OF THE USSR
BY STANDARDS

ALL-UNION RESEARCH INSTITUTE
FLOW METERS (VNIIR)

METHODOLOGICAL INSTRUCTIONS

STATE SECURITY SYSTEM
UNITS OF MEASUREMENT

WATER CONSUMPTION ON RIVERS AND CHANNELS.
MEASUREMENT PROCEDURE
BY THE “SPEED - AREA” METHOD

MI 1759-87

Moscow
PUBLISHING HOUSE OF STANDARDS
1987

DEVELOPED by the State Hydrological Institute State Committee USSR on hydrometeorology and environmental control

PERFORMERS:

Karasev I.F.,doc. tech. Sciences, Professor (topic leader), Savelyeva A.V., Ph.D. tech. sciences, Remenyuk V.A., Ph.D. tech. sciences

PREPARED FOR APPROVAL by the All-Union Scientific Research Institute of Metrological Service

Art. department expert Treyvas L.G.

APPROVED by the All-Union Scientific Research Institute of Flow Measurement at the NTS Institute on June 11, 1986, protocol No. 8

METHODOLOGICAL INSTRUCTIONS

GSI. Water consumption on rivers and canals. Execution method
measurements using the “velocity - area” method

MI 1759-87

Put into effect

These guidelines establish the basic principles of the methodology for measuring water flow on rivers and canals using the “velocity - area” method using hydrometric meters to measure flow velocities.

The use of methodological instructions ensures the total relative error in water flow measurementsS Q, no more:

6% - with the detailed method;

10% - with the main method;

12% - with the accelerated-shortened method.

MU do not apply to measuring water flow using floats and integrating flow velocities across the width of the stream.

Definitions and explanations of terms found in the text are given in the appendix.

1. PRINCIPLE OF MEASURING WATER FLOW BY THE “SPEED - AREA” METHOD AND CLASSIFICATION OF ITS OPTIONS

1.1. The essence of the method and principles of measurement

1.1.1. The velocity-area method is a type of indirect measurement of water flow. In this case, as a result of observations at a fixed hydrometric site, the following flow elements are determined:

depths on the measuring verticals and their distance from the constant origin along the gauging line, to determine the water cross-sectional area (with an accuracy of three significant figures, but not more precisely 1 cm);

longitudinal (normal to the hydrometric section) components of average current velocities on verticals, on the basis of which average velocities in the compartments between them are calculated (with an accuracy of three significant figures, but not more accurate than 1 cm/s).

1.1.2. Water consumption is calculated from its elements in one of the following ways (accurate to three significant figures):

analytical, as the sum of partial water flows passing through the compartments of the water cross-section of the flow, limited by high-speed verticals;

graphically, as the area of a diagram of the distribution of elementary water flow rates along the width of the stream.

1.1.3. When calculating water flow, the main hydraulic characteristics of the flow, used in assessing the accuracy of measurements and accounting for river flow, must also be determined:

water level above zero point N;

water cross-sectional areaF;

average and highest current speeds:v And v n (v = Q/ F); v n is the highest of the speeds measured by the pinwheel;

water section width IN;

flow depth: mediumh Wed and greatest h n ( h Wed = F/ B); h n is the largest of those measured on the measuring verticals.

1.2. Classification of measurement methods

1.2.1. Depending on the methodology for determining average vertical speeds, integration and point methods are distinguished.

1.2.2. The integration method is based on measurement average speed flow on the vertical with a turntable, uniformly moved in depth.

1.2.3. Point methods based on determining the average vertical flow velocity based on the results of measurements at points are divided into:

the main method is when measuring vertical current speed at two (free channel) or three points (presence of aquatic vegetation, ice cover);

a detailed method - when measuring vertical current speed at five (free) or six points (freeze, aquatic vegetation).

At shallow depths (see table), the use of a single-point method is allowed.

1.2.4. For the main method of measuring water flow in a single-branch channel, 8 - 10 speed verticals are assigned.

In the case of using a detailed method, the number of high-speed verticals increases by 1.5 - 2 times. The detailed method is used in scientific and methodological work to assess the accuracy and optimization of water flow measurement processes - to clarify the number of measuring and velocity verticals, as well as to justify the possibility of switching to the main method in a given hydraulic reservoir.

The shortened method of measuring flow allows the use of less than eight velocity verticals with two- and three-point measurement of velocities on verticals (similar to the main method).

2. HYDROMETRIC SITE SECTION

2.1. The hydrometric gauge (hereinafter referred to as the hydraulic gauge) is part of the hydrological post along with its devices for measuring levels, water temperature and other elements water regime rivers (canals). The section of the hydraulic gauge refers to the part of the river directly adjacent to the hydraulic gauge at a distance of two to three widths of the channel from above and below the stream.

2.2. The conditions for measuring water flow are considered normal if the straightness of the channel is observed at the hydraulic section:

there are no sharp breaks, the profile of the water section and the velocity distribution diagrams along the width of the flow are stable;

the correct unimodal, convex profile of the distribution of flow velocities along the depth of the flow is ensured;

there is no pronounced pulsation of the flow velocity in value and direction, as well as significant systematic skewness of the flow;

there is no interference when measuring current speeds, depths, water levels and coordinating speed and measurement verticals.

location of the hydraulic dam in the river reaches;

lack of floodplain with channels and branches;

absence of natural or artificial barriers;

absence of aquatic vegetation in the hydraulic reservoir itself, as well as above and below it at a distance of up to 30 m;

coefficient of variation of speed (Karman numberKa) on average over the cross section should be no more than 15%;

the obliquity of the flow at the hydraulic section (deviation in terms of flow directions at individual points from its average value for the section as a whole) should be no more than 20°;

dead spaces must have clear boundaries and amount to no more than 10% of the water cross-sectional area;

during freeze-up there should be no multi-tiered ice cover and non-freezing polynyas;

the pollution of the riverbed should not exceed 25% of the water cross-sectional area;

the average flow velocity in the live section must be no less than 0.08 and no more than 5 m/s;

when measuring water flow near a bridge, the section of the hydraulic gauge should be located above, but in cases of frequent accumulations of ice and forest breaks - below the bridge (at a distance of at least 3 - 5 channel widths in both cases).

2.4. In all cases, where possible, in order to bring the site into compliance with the requirements of the settlement, work must be carried out to streamline and drain the riverbed.

2.5. The hydraulic dam should be located on a single-branch section of the river. If necessary, it is allowed to designate a hydraulic gate” at the site where the channel branches into branches and channels.

3. HYDRAULIC VALVES AND THEIR EQUIPMENT

3.1. Location and direction of the hydraulic dam

This requirement is considered to be satisfactorily met if the following conditions are met:

for floodplain sections of rivers - the average value of the deviation of the flow direction from the normal to the hydraulic gauge (slope of streams in plan) on high-speed verticals should not exceed ± 10°;

for floodplain sections of rivers - the average slant of streams on high-speed verticals should not exceed ± 20°. If the average flow directions in the main channel and on the floodplain diverge by more than 20°, it is allowed to divide the hydraulic gate in the form of a broken line, sections of which correspond to the condition of perpendicularity to the direction of the currents.

3.1.2. In cases where the direction of the hydraulic gate satisfies the specified requirements only at a certain filling of the channel, for these different phases of the water regime, hydraulic gates must be equipped that meet the conditions of paragraph.

3.2. Hydraulic sump equipment

3.2.1. The hydraulic valve must be fixed to the ground steel rope or a gauging bridge, or leading signs. Aiming marks must be clearly visible from the river and ensure the maximum deviation of the vessel from the aiming line g = 1° (angle g formed by the hydraulic alignment line and the line of sight passing through the alignment marks and the hydrometric vessel, and the apex of the angle g coincides with the position of the leading sign closest to the river).

3.2.2. A coastal sign (post, benchmark, etc.) is installed at the site, fixing a constant beginning for counting distances to the shore edges, measurement and speed verticals, boundaries of dead space and whirlpool zones.

3.2.4. When coordinating measuring verticals using geodetic methods, the site is additionally equipped with a station for a goniometer instrument.

4. WATER LEVEL MEASUREMENTS

4.1. Whenever water flow is measured at a hydrological station, the corresponding water level must be measured.

The rules for performing water level measurements must comply with the requirements of GOST 25855-83.

The time of each level measurement is recorded.

4.3. If there is an additional level post (p.) in the hydraulic reservoir, level observations should be carried out at both posts: the main and additional ones.

5. COORDINATION OF MEASUREMENT AND SPEED VERTICALS IN THE HYDRAULIC DESIGN

5.1. Ways to coordinate verticals

5.1.1. The location of the measuring and velocity verticals in the hydraulic reservoir is determined by the distance from the permanent beginning.

5.1.2. At hydraulic gates equipped with a boat, ferry or cradle crossing with a permanently suspended marking rope or hydrometric bridge, it is necessary to secure the position of the verticals in accordance with clause .

5.1.3. If there is a strong ice cover, the location of the verticals should be determined by a theodolite move on the ice or with a measuring tape.

5.1.4. On navigable rivers or with a section width of more than 300 m, the location of the verticals should be determined by notching with theodolite or kipregel from the shore.

In some cases (for example, in conditions of swampy or wide floodplains, etc.), it is allowed to use oblique or fan-shaped sections to secure working verticals.

5.2. Accuracy of coordination of measuring verticals in a hydraulic reservoir

5.2.1. The relative root mean square error of the coordination of verticals in the hydraulic reservoir () must satisfy the requirement

(5.1)

where s to - absolute root-mean-square coordination error, m;

B- river width, m.

5.2.2. When assigning places for mensular (theodolite) parking, it is necessary that the angle formed by the direction of the hydraulic channel and the sighting beam a was at least 30°.

5.2.3. Length of lines on the planl(cm) when photographing scales, must satisfy the condition

(5.2)

Where L- length of the line on the ground, m.

5.2.4. Absolute coordination error s to , caused by the vessel's deviation from the hydraulic station ( D X, m), is determined by the dependence

(5.3)

where D X Wed - average deviation of the vessel from the hydraulic station, m (table);

a cp - the average value of the angle formed by the sighting beam and the direction of the hydraulic valve.

The value of the vessel's deviation on each vertical is determined by the distance between the leading marksl c and moving the vessel away from the nearest markL c . The permissible distance between leading signs is determined by the dependence D X Wed from l with and L c in table .

Table 1

L s, km

h- vertical depth, m;

D X d = h. (5.5)

6. MEASUREMENT OF DEPTHS AND CALCULATION OF COMPARTMENT AREA BETWEEN SPEED VERTICALS

6.1. Depth measurement accuracy requirements

6.1.1. Depth measurements must be made along the hydrometric alignment line in compliance with the requirements of paragraph.

6.1.2.. Measuring instruments must provide determination of the depth at a point with an instrumental error of no more than 2%. This requirement must meet existing and newly developed depth measurement tools.

a hydrometric rod or marking should be used in all cases when the greatest depth in the target does not exceed the length of the instrument and the measurement conditions allow the rod to be firmly fixed on the vertical and the depth taken (if these requirements are not met, it is necessary to use a measuring rope with a hydrometric weight or an echo sounder);

at each measuring vertical, the vessel must be anchored or fixed on a cable crossing;

when working in channels with a muddy bottom, markings and rods should be used, equipped with a round tray with a diameter of 12 - 15 cm, which prevents them from immersing in the silt;

When taking measurements with a rod on rivers with a solid rocky bottom, a rod without a cone-shaped tip should be used.

Cargo weight, kg

Table 3

	Angle of deviation of the rope from the vertical, degrees

6.1.6. On shallow mountain rivers, depth should be determined as the difference in distances to the bottom and the surface of the water, measured with a rod or mark from a rope pulled across the river, bridge decking, etc.

6.1.7. When water approaches the rod, it is necessary to use a metal slider that moves freely along the rod with an arrow indicating the water surface outside the area of the impact.

6.2. Depth measurements at a hydraulic gauge when measuring water flow

6.2.1. Depth measurements are taken to determine the water cross-sectional areaF and its compartments f V . If the channel is stable, it is permissible to use the results of previous measurements and not carry them out each time the water flow is measured. The stability of the channel is assessed based on the analysis of combined cross-sectional profiles of the flow along the hydraulic channel, as well as from the scattering of empirical connection pointsF(N) - dependence of the water cross-sectional area on the water level.

vertical deformations of the channel are pronounced, but during the measurement of water flow they do not exceed the permissible root-mean-square error of depth measurements;

the channel is stable, free from ice formations, but flow measurements are carried out sporadically (once or twice during the characteristic phase of the hydrological regime).

6.2.4. Depth measurements should be taken with each two-pass water flow measurement if:

vertical deformations of the channel during flow measurement exceed the permissible root-mean-square error of depth measurements;

water flow is measured less than three times per water content phase and slush and inland ice are noted in the live section;

The channel at the measurement site is uneven, composed of boulders or with bedrock outcrops.

6.2.5. In cases where it is difficult to take measurements on the floodplain, the depths in the floodplain part of the hydraulic gauge should be determined from the profile obtained by instrumental survey during the low-water period, taking into account the actual water levels.

6.2.6. In the first two to three years of operation of a hydrological post, depth measurements should be carried out in two steps for each measurement of water flow to justify subsequent measurements made in accordance with paragraphs. , .

6.3. Number of measuring verticals

6.3.1. The number of measuring verticals (or notches of the location of the hydrometric vessel when taking measurements using an echo sounder) should be assigned depending on the shape of the water section profile, based on the requirement: the relative root-mean-square error in measuring the cross-sectional area should not exceed 2%.

6.3.2. In the main channels of lowland and semi-mountain rivers there is a minimum number of measuring verticalsn h(min) should be prescribed in accordance with table. depending on the channel shape parameter.

Table 4

6.3.3. If the distribution of depths across the width of the stream is non-uniform, it is necessary to assign additional measuring verticals in the hydraulic channel at all sections of the bottom line break.

6.4. Location of measuring verticals

6.4.1. In the main channels, measuring verticals should be placed evenly across the width of the river and additionally at the turning points of the transverse profile.

6.4.2. On rivers with unstable beds in the zone maximum depths the number of measuring verticals should be increased by 1.5 times.

6.5. Calculation of working depth vertically

6.5.1. The working depth on the verticals should be calculated according to the existing transverse profile, taking into account level cutting if there is a discrepancy between the levels when taking measurements and measuring water flow. When measuring water flow, data from preliminary measurements is used.

6.5.2. When performing depth measurements in two strokes, the working depth on the verticals is calculated as the arithmetic mean of the two measurements.

6.5.4. As working depths, it is necessary to take depths with excluded systematic deviation in accordance with paragraphs. And .

6.6. Calculation of the water cross-sectional area of a flow

6.6.1. Areas of water sectionsfsmust be calculated by the following formulas:

(6.2)

Where m s- number of measuring verticals ins-m section compartment;

h i- working depth ati th vertical, m;

b i, i +1 - distance betweeni-th and ( i+ 1)th measuring verticals.

6.6.2. The water cross-sectional area of the flow should be determined by the formula

(6.3)

Where N- number of compartments of the water flow section.

6.6.3. If present in the water section dead zones space, water flow is calculated based on the open cross-section of the flowF

(6.4)

Where - areas between high-speed verticals that limit the dead space of the flow.

7. MEASUREMENT AND CALCULATION OF THE AVERAGE SPEED OF CURRENTS ON THE VERTICAL

7.1. Assignment of the number and position of speed verticals for the main and detailed methods of measuring water flow

7.1.1. Number of high-speed verticals in the alignmentNvshould be from 8 to 15, depending on the characteristics of the velocity field of the flow. With a unimodal plan plot of surface velocitiesNv= 8 - 10; with a multimodal shape of the velocity diagramNv= 12 - 15. For special precise measurements in a steady state, the number of high-speed verticals can be increased.

in the main part of the flow, high-speed verticals must be assigned in such a way that the sections of the open section, limited by adjacent high-speed verticals, pass the same partial flow ratesqsfull flowQ, components

qs ≈ Q/ N. (7.1)

With the multimodal nature of the distribution of surface velocities across the width of the river, additional velocity verticals are assigned at characteristic points of the planned velocity diagram:

high-speed verticals are assigned only within the clear cross-section of the flow. The boundaries of dead spaces must be established before or during the measurement of velocities by launching surface floats or based on the results of reconnaissance measurements of velocities with a turntable;

coastal verticals, as well as verticals bordering the dead space of the water section, are assigned at such a distance from the banks or dead space that the partial water flow in the edge compartment does not exceed 30% of the partial flow of the main zone of the live section;

on the floodplain, speed verticals should be assigned at characteristic points of the transverse profile. In the depressions of the floodplain, where isolated streams are formed that allow partial flow throughqs > 0,1 Q, it is necessary to assign at least three speed verticals.

7.2. Point methods for measuring average vertical flow velocity

7.2.1. Current velocities are measured on high-speed verticals using hydrometric meters that comply with GOST 15126-80.

7.2.2. The number of measurement points and their relative depth below the surface of the water (ice) is assigned depending on the method of measuring water flow, the method of attaching the hydrometer in the flow, the state of the channel and the depth ratio on the high-speed verticalhand diameter of the rotor bladeDin accordance with table. .

Table 5

v = q/ h, (7.11)

Where q- elementary flow rate, m 2 /s, which is the area of the velocity diagram on the scale of the drawing, obtained as a result of planimetry.

7.5.3. When working with a turntable on a rope suspension in conditions of obliqueness, characterized by an average angle of deflection a the direction of the jets on the vertical from the normal to the hydraulic valve, the average speed on the vertical must be determined by the formula

7.6.1. When performing integration measurements of vertical speed, it is necessary to maintain the following relationship between the speed of movement of the turntablewand longitudinal flow velocityv, depending on the permissible integration error δ d:

δ d (%)
w/v	0,12	0,16	0,24	0,30	0,44.

7.6.2. The longitudinal component of the average flow velocity on the high-speed vertical is established using the calibration graph of the turntable according to the rotational speed of the bladed propeller, defined as the quotient of dividing the total number of propeller revolutions during the integration time by the integration time.

7.6.3. During the integration measurement of velocity on the vertical, the average value of the velocity is calculated using the formula (), while the value of the average angle of skewness on the vertical is taken according to the data of special observations carried out in accordance with paragraph.

7.6.4. To eliminate the systematic positive error in the integration of the average velocity on the vertical, caused by incomplete illumination of the near-bottom zone of the flow, a correction factor should be introduced into the measured velocity valueKh.

A	0,30	0,20	0,15	0,10	0,05
Kh	0,90	0,93	0,95	0,97	0,98,

Where A- relative minimum distance of the spinner axis from the bottom of the stream (in fractions of the depth).

8. PROCESSING MEASUREMENT RESULTS AND CALCULATING WATER CONSUMPTION

8.1. Calculation of water flow based on a linear deterministic model with a basic or detailed measurement method

8.1.1. In accordance with the linearly deterministic model (hereinafter referred to as the LD model), water flow is calculated using the formula

(8.1)

Where f i- area of the live flow sections,i = 1 ... P.

Calculation of average vertical speedv imust be carried out in accordance with paragraphs. And . The procedure for calculating the areas of the cross-sectional sections of the flow is given in Section. .

8.1.2. OddsK i And Kn for speeds v i And vnon coastal high-speed verticals in the absence of dead space are taken equal to:

0.7 - with a flat bank with zero depth at the edge; near the border of the accumulation of motionless slush;

0.8 - with a natural steep bank or uneven wall (rubble, rough stone);

0.9 - with a smooth concrete or completely boarded wall, as well as with water flowing over ice.

If there is dead space in the coastal zone, the coefficientsK 1 and Knare equal to 0.5, respectively.

8.1.3. The LD model can be used when calculating water flow for the number of high-speed verticalsNv, satisfying the requirements of paragraph .

8.2. Calculation of water flow based on an interpolation-hydraulic model with a reduced measurement method

8.2.1. The use of a shortened measurement method with subsequent calculation of water flow using an interpolation-hydraulic model is advisable and is allowed if, when reducing the number of high-speed verticals to three to five (for flows with a cross-sectional width of more than 10 m), deviations of the measurement results from the values obtained by a detailed method are random in nature, and the standard deviation does not exceed 5%.

8.2.2. According to the linear interpolation-hydraulic model (hereinafter referred to as the LIG model), water flow should be calculated using the formula

(8.2)

where D s - number of water flow compartments;

i, j- limiting indicess- th compartment of high-speed verticals;

P s- a weighting coefficient equal to 0.7 for coastal sections and 0.5 for the main water section;

A- hydraulic coefficient, calculated by the formula

(8.3)

Where Nv- number of speed verticals in the live section.

8.2.3. In the case when the flow section consists of pronounced hydraulically isolated zones (for example, separated by a flooded middle), in each of them it is necessary to calculate the water flow as for a separate channel, and the total flow in the hydraulic section is determined by summing these values.

8.2.4. Coastal high-speed verticals (or sections closest to the border of separate zones) should be located at a distance of no more than 0.3b kfrom the edges (or boundaries of isolated zones), whereb k- the width of the corresponding hydraulically justified zone of the live section.

8.3. Graphical method for calculating water consumption

8.3.1. It is advisable to use the graphical method in case of complex distribution of velocities along the depth and width of the flow, ensuring sufficient a large number of(at least five) points for measuring flow velocities on the vertical and the number of verticals in the sectionNv³ 8.

8.3.2. Water consumption is calculated in the following order:

a cross-sectional profile is drawn on graph paper according to the calculated water level and the depths given to it, with velocity verticals applied;

Diagrams of the distribution of flow velocity along the vertical are drawn and the average speeds on the verticals are determined by planimetricizing the areas of the diagrams expressing the elementary flow rate of water on the high-speed verticals (see paragraph);

a smooth diagram of the distribution of average velocities on the vertical along the width of the flow is applied to the profile of the open sectionv (V);

based on diagram v (V) and the depth profile, a diagram of the distribution along the width of the flow of elementary water flow is constructedq(V);

water flow is determined as the area of the diagramq(V).

8.3.3. Image scale of diagrams of distribution of velocities, depths and specific costs should be selected so that all elements of water flow, calculated graphically, are placed on a sheet of graph paper measuring 407´ 288 or 407 ´ 576 mm.

The most convenient image scales are:

for velocity diagrams: vertical - 1 cm 0.5 m; horizontal - 1 cm 0.2 m/s;

for depth profile: vertical - 1 cm 0.5 m; horizontal - 1 cm 2, 5, 10, 20 m;

for the elementary flow curve: vertical - 1 cm 1 m 2 / s

8.4. Calculation of the level corresponding to the measured water flow

8.4.1. To plot the flow curveQ(N) measured water flowQmust match the level N, at which the flow rateQ measured:

(8.4)

Where Hs- water level corresponding to partial flowqs, obtained by interpolation between the observed level values (see paragraph).

8.4.2. If the relative change in level during the measurement of water flow does not exceed 2% of the average depth of the section, a simplified formula is applied

(8.5)

Where H n and H To - respectively, water levels in the initial and final periods of measurement.

8.4.3. The calculated level determined for the additional post is brought to the level at the main post through the connection of the corresponding levels.

8.5. Operational control of measurement accuracy

8.5.1. Monitoring the accuracy of measurements should be carried out directly at the hydraulic station when taking measurements. Doubtful values of water flow elements (depth, speed, distance, level) are clarified and corrected or confirmed by repeated measurements.

8.5.2. With a stable (unambiguous) relationship between flow and levels, water flow is measured in order to control the stability of the long-term flow curveQ(H). In turn, this curve is used to operational control accuracy of measurements and identification of observation errors based on the criterial ratio

Where S Q- relative, total measurement error;

δ d - permissible error.

9.1.3. The stated optimization problem belongs to the class of incorrect ones, since it allows for ambiguity of solutions, i.e. non-uniqueness of the choice of the optimal vector of detail characteristics. In practice, it is enough to stop at any vector (Ns, ns, Nm), satisfying condition () and providing sufficient convenience and safety, satisfactory labor intensity and energy intensity of the process of measuring water flow.

9.1.6. For practical calculations, it is permissible to evaluate the components and based on graphical dependencies on the devil. And .

Dependence of the relative random mean square error in measuring the area of the living section compartment on the number of measuring verticals and the section shape parameter

ns- number of measuring verticals in the compartment; j - section shape parameter

Crap. 1

Dependence of the relative random root-mean-square error in measuring the average speed in the compartment from Karman's numberKaand average number of pointsNmvertical speed measurements

Crap. 2

9.2. Optimizing measurement duration

9.2.1. Duration of the measuring processT And is one of the determining factors for the accuracy of flow measurements: with decreasingT And the error increases due to insufficient averaging of velocity pulsations; with increasingT And the error increases due to the “cutting off” of peaks and dips in water content during the passage of waves of releases and floods. DurationT And must be in the range

T min £ T and £ T max , (9.5)

Where T min And T max - minimum and maximum permissible duration of the measuring process.

Time T min is determined from dependency(), andT max - according to the formula

(9.6)

Where T P - period of fluctuation of release waves (flood), hours or days;

j - phase of the oscillation period, which accounts for the middle of the measurement time intervalT And ; 0 £ j £ 2 p ;

A- relative amplitude of release waves

(9.7)

Where Q max and Q With - maximum and average water flow rates during the release period, respectively.

10. REQUIREMENTS FOR THE QUALIFICATIONS OF THE CONTRACTOR AND WORK SAFETY

10.1. Performer qualification requirements

10.1.1. The qualifications of the observer must correspond to the conditions, means and methods of measurement.

On small rivers, in conditions of low flow and shallow flow depth, when wading observations are permissible, and only a turntable and a hydrometric rod are used from the technical means, as well as in other cases, it is permissible to involve technical personnel with the qualification of a hydrometeorological observer, specially trained and instructed, in measuring water flows regarding the characteristics of measurements in a given section.

10.1.2. In cases where more complex technical means(for example, remote installations, various types of ship systems, echo sounders, etc.), as well as during periods of increased danger of observations with high water content of the stream, significant depths and flow speeds, with instability of the channel, significant slanting of the flow and other factors complicating measurements work should involve performers with qualifications no lower than a hydrological technician.

10.1.3. The observer must know the principle of operation and design of measuring instruments and be able to handle them when performing measurements; know the water and channel regime at the measurement site and the conditions for their implementation at various phases of the regime; be able to use electronic calculators to process water flow rates and measurement results.

10.2. Work safety requirements

10.2.1. Only persons who have undergone safety training are allowed to measure water flow in open channels. The results of the briefing are recorded in a special journal stored at the hydrological station.

10.2.2. When performing measurements of water flows, it is necessary to be guided by the “Safety Rules for Observations and Work on the Goskomhydromet Network” (Gidrometeoizdat, 1983).

11. MEASURING INSTRUMENTS AND AUXILIARY DEVICES

11.1. When performing water flow measurements, the measuring installations, measuring instruments and devices given in table should be used. .

Table 7

	Name of measured physical quantities and parameters
Hydrometric turntable: GR-21, GR-99	Average flow rate
Kipregel	Horizontal distance to sighting point
Theodolite
	Excesses
Leveling rod
Portable water measuring rod GR-104	Water level
Water measuring rod with damper GR-23	Wave water level
Ice snow gauge GR-31	Ice thickness
Maximum rail GR-45	Highest level between observation periods
Hydrometric rod GR-56	Flow depth
Level recorder: SUV-M "Valdai", GR-38	Continuous recording of water level
Stopwatch	Duration of measurements
Installation for measuring water flow remotely: GR-70, GR-64M	Depth and speed of flow, distance from permanent beginning
Hydrometric winch	Flow depth
Measuring tape	Distance
Hydrometric weight: GGR, PI-1	Flow depth
Marking rope	Distance from constant origin
Hydrometric cradle
Hydrometric bridge
Rope crossing	WITH Y- coefficient of variation of elements (2.1) where s ( Y) - standard deviation of the element, - mathematical expectation of valuesY(X) And Y(t), ξ to - correlation radius (p.) (2.2) t to - average correlation time (2.3) Where R(ξ) And R(t ) - autocorrelation functions respectively forY(X) And Y(t). Determination of ξ to and t to it is convenient to produce functions using graphsR(ξ) to R(t ), calculated using a standard computer software program for a given sample of values (Y(X)) And ( Y(t)}.

Water flow measurement hydrometric turntable

Multipoint (detailed) method provides for measuring water flow along an increased number of speed verticals (10-15 compared to the usual) with speed measurement at 5-10 points (rotate: 0.2; 0.6; 0.8; bottom - with a free channel; rotating: 0.2 ;0.4;0.6;0.8;bottom - when the channel is not free) on each vertical. The multipoint method gives the most accurate flow rate.

The main way when the number of speed verticals is reduced by 1.5-2 times compared to the detailed one, and flow velocities are measured at 2-3 points on each vertical.

Integration method vertically is used at depths of more than 1 m and flow velocities of more than 0.2 m/s. The measurement is carried out using the integrated installation GR-101.

Fast way used for rapid changes in level during the measurement of water flow with intense deformation of the channel, in the presence of variable backwater and in other unfavorable conditions.

Shortcuts provide for measuring water flow by average speed at 1-2 representative verticals or a unit speed at a point 0.2 of its working depth.

Measuring water flow with floats

Measurements with surface floats. The accuracy of float measurements is significantly lower than that of rotary measurements. At intensive ice drift, when pinwheel measurements become impossible, and individual ice floes serve as floats.

Measuring water flow with deep floats and integrator floats

Floats of this type are used to measure relatively low current velocities (up to 0.15-0.20 m/s), when spinner measurements are not very reliable.

Hydraulic water flow measurement

It is used when it is not possible to measure water flow by other methods. Water consumption is calculated using the formula

Q=VavF, Vav=C RJ,

where R is the hydraulic radius; J-longitudinal slope; C-rate coefficient or Chezy coefficient C=1/nR x-1.5 n at R<1 м;x-1,3 n при R>1m.

Observations of river levels

The results of observations of levels make it possible to establish the zones and duration of flooding of individual sections of the river valley, the speed of movement of the flood wave along the river (in the event that “the river has at least two water-measuring posts) and draw conclusions about general character changes in river water content throughout the year over a long-term period, the highest floods, etc.

Among these so-called characteristic levels, the levels of greatest practical interest are: 1) the highest annual, 2) spring ice drift, 3) autumn ice drift, 4) summer and autumn floods, 5) the lowest summer and winter.

River flow - movement of water in the form of a stream along a river bed.

Occurs under the influence of gravity. Is the most important element the water cycle in nature, through which water moves from land to oceans or areas of internal drainage. The quantitative value of runoff per unit time is called water flow.

In hydrology, river flow usually means the volume of runoff - the volume of water passing through a certain section per unit of time, most often a year. Unites surface runoff(formed as a result of precipitation and snowmelt) and underground runoff formed due to groundwater. River flow over a year is an objective indicator for determining the fullness of a river.

The main characteristic of river flow is water flow.

All other characteristics of river flow, in fact, are derived from the corresponding water flows. Let us consider the most commonly used characteristics of river flow.

Runoff volume W (m 3, km 3) - the amount of water flowing from the catchment area over any time interval (day, month, year, etc.).

Runoff module M (l/s * km 2) or q [m 3 / s * km 2)] is the amount of water flowing from a unit of catchment area per unit of time.

Runoff layer h (mm) - the amount of water flowing from a catchment area over any time interval, equal to the thickness of the layer evenly distributed over the area of this catchment area.

Runoff coefficient is the ratio of the runoff layer to the amount of precipitation that fell on the catchment area, causing the occurrence of runoff.

Annual runoff is calculated in temperate climates for the hydrological year beginning in the fall (October 1 or November 1), when the moisture reserves in river basins moving from one year to another are small.

To measure flow speed, two types of instruments are used: electrical and mechanical. In many current measurements, both mechanical and electrical, the current speed sensor is an impeller rotating on an axis, and the direction sensor is a magnetic compass. All these devices are based on measuring the number of revolutions of the impeller over a certain period of time. This is done using a mechanical (Ekman turntable) or electrical (Roberts current meter) counter. IN Lately The Savocius rotor, the revolutions of which are recorded by an electric meter, and the Alekseev direct-printing turntable are widely used. In Alekseev's turntable, recording is made on tape using special device after a certain number of turns of the turntable.

In the practice of limnologists, resistance thermometers-thermohydrometers are also used to determine flow speed, based on changes in the resistance of thermocouples depending on the speed of the water flow washing these sensors. Recently, improved electrical recording meters of current speed and direction have appeared - ACIT.

To establish the nature of the relationship between costs and levels, it is necessary to carefully check and analyze starting materials. These include: 1) table “Measured water flows” (WW); 2) table “Daily water levels” (DWL); 3) combined cross-sectional profiles along the hydrometric alignment; 4) plan of the post site; 5) transverse profile along the hydraulic valve to the level high waters; 6) technical matter of the post; 7) literary and archival materials characterizing the river regime at the gauging section.

Flow measurements using surface floats have a significantly lower accuracy than measurements using turntables, so surface floats are used in reconnaissance surveys of rivers when turntables fail. During intense ice drift, when measurements with turntables become impossible, individual ice floes can serve as floats.

Rice. 31.

AB - launch point; I- basis; 2 - upper; 3 - main;

4 - lower section of the river

Float measurements are carried out in calm conditions or a slight wind of 2-3 m/s. To measure velocities with surface floats in a section of the river that meets the requirements for hydrometric gauges, a highway is laid along the bank parallel to the main direction of the flow and a basis is selected on it - I(Fig. 31). Three alignments are broken perpendicular to it: the upper one - 2, the main one - 3 (middle) and bottom - 4. The distance between the alignments is such that the duration of the floats between them is at least 20 s. Main site 3 breaks approximately in the middle of the base.

If a bridge is used to simplify and speed up hydrometric work, then the main alignment is combined with the bridge alignment.

The position of the base and alignments on the ground is fixed with pegs and milestones. At the sites, cables marked at 1 m intervals can be stretched over the water. At all points along the water's edge, stakes are driven in; their distance to the base is measured with a measuring tape. To launch the floats, the launch gate AB is additionally broken 5-10 m above the top target.

Depth measurements are taken and the open section area along the main section is determined. Measurements are taken under each mark of the marked cable, starting from the “permanent beginning” (cutting stake). The measurement results are entered into a table. In the absence of a marked cable in the alignment, the distance from the measuring vertical to the shore is determined by the notch method, i.e. by measuring the horizontal angle between the base and the line of sight (see Fig. 15). The location of the measurement point on the target is controlled by milestones placed on the shore.

Measuring water flow velocities with floats is carried out in the following order. At the launch site, 15-25 floats are thrown into the water in succession, distributed approximately evenly across the width of the river. When a float passes through the gates, observers give signals with a go-ahead signal or voice. At these moments, the place of passage (distance from the shore) of the float in each alignment is recorded using the notch method or by an observer on the bridge using marking cables. At the same time, a stopwatch is used to measure the time it takes the float to travel from the top to the bottom.

Rice. 32.

The results of measuring the speed of the floats are recorded in a table. Moreover, records of floats washed ashore are excluded. In Fig. Figure 32 shows the distribution of float travel times across the river width. On the graph, the distances from the permanent beginning to the place where the floats pass the middle alignment are plotted along the horizontal axis, and along vertical axis- duration of travel of the floats between the upper and lower sections. Using the plotted points, an averaged diagram of the distribution of the duration of the float's stroke across the width of the river is drawn. Velocity verticals are drawn at equal distances and in places where the diagram is inflected. At least 5-6 high-speed verticals are assigned, which are combined with measuring verticals for ease of processing. For each speed vertical, the surface velocity of the current is calculated by dividing the distance between the upper and lower gates by the duration of the float stroke, taken from the diagram. The results of measuring water flow rates by floats are recorded in a table.

By multiplying the areas of the compartments between the velocity verticals by half the sum of the surface velocities on them, partial fictitious water flows are obtained. Their sum, taking into account the marginal coefficients, gives the total fictitious water consumption (2f:

where vi, v„ are surface velocities on high-speed verticals; coi, ..., co„ - areas of living sections between high-speed verticals; To- coefficient for the edge section equal to 0.7.

The actual flow rate is calculated using the formula:

Where TO- transition coefficient, from fictitious flow to real.

The value of the transition coefficient A^i can be found in tables or determined using formula 5.6, if Q- flow rate determined simultaneously by measurements with a turntable and floats. You can also define TO according to the formula:

Where WITH- Chezy coefficient, which is recommended to be calculated using the formula N.N. Pavlovsky:

where at R 1m And at R> 1 m; P- coefficient

roughness, determined from tables in hydraulic reference books.

If it is impossible to launch floats across the entire width of the river, for example on fast-flowing rivers where the floats are carried towards the middle of the flow, water flow is determined by the highest surface velocity. In this case, 5-10 floats are launched onto the core part of the flow. Of all the launched floats, three with the longest stroke duration are selected, differing from each other in time by no more than 10%; with a larger deviation in the stroke duration, another 5-6 floats are launched.

If the highest surface velocity is measured using floats, it is used to calculate water flow

where K max is the average speed of the three fastest floats; coefficient TO

Where AND- average flow depth; g - free fall acceleration; co is the water cross-sectional area.

Measuring water flow with deep floats is used to measure relatively low flow velocities (up to 0.15-0.20 m/s), when spinner measurements are unreliable and to determine the boundaries of dead space. Current speeds are measured from a boat equipped with

secured by three rigidly fastened parallel slats at a distance of 1 m from each other. Using a pole at a distance of 0.5 m from the slats (upper) located closer to the bow of the boat, a deep float is launched. A stopwatch is used to determine the time it takes the float to travel the distance from the upper to the lower target. At each point the float is launched at least three times. The speed at a point is calculated by dividing the length of the base - the distance between the gate slats - by the average duration of the float stroke. The average value is taken into account. Water flow is calculated analytically in the same way as water flow measured with a pinwheel.

In river hydrometry, the most common method for measuring water flow is speed method-square". It lies in defining water section area by measuring depths along the hydraulic channel and measuring with a hydrometric measuring instrument at individual points of the water section flow speed.

When measuring water flow you must:

1) record the work environment;

2) monitor the water level;

3) measure depths at the hydrometric site;

4) measure the speed of water flow at individual points of the live section on high-speed verticals.

All records of observation data and measurements of water flow are made with a simple black pencil in the “Book for recording water flow measurements” KG-ZM *.

Before starting work, it is necessary to check the serviceability of the hydrometric turntable and its accessories, the stopwatch, as well as the presence and serviceability of life-saving equipment to ensure the safety of work, the condition of all equipment of the hydrometric station (Appendix 1). To prevent accidents, students are required to study and strictly follow the safety instructions (Appendix 2).

To measure water flow, a section of the river is selected that meets, if possible, the following requirements:

1) the banks are smooth (not winding), parallel;

2) the channel is level, stable and not overgrown with vegetation;

4) absence of dead space (part of the water section where there is no flow).

For educational practice, the selected section of the river must have depths of more than 1 m so that patterns of changes in flow speeds can be identified.

In the selected area, a hydrometric gauge (hydraulic gauge) is marked, at which water flow is measured. On small rivers, the waterworks are laid out by eye perpendicular to the direction of the river flow and secured on both banks with signs - stakes. A sign on one of the banks is taken to be constant start from which distances are measured before each measuring (speed) vertical. A cable (cord) marked every 1 m is stretched in the hydraulic channel. If measurements are made from a boat, a riding cable is stretched parallel to the marking cable (under it), which serves to move the boat along the channel and position it vertically.

Observations and measurements are carried out in the following order.

1. Information about the work environment (state of the river, weather, instruments and equipment) is recorded in the “Work Environment” section of the expense book. All phenomena that may affect the direction and magnitude of the flow velocity or affect the accuracy of determining water flow are noted. For example, the width of the mowed strip of the hydraulic drain is indicated and it is noted in what condition it is: “cleanly mowed”, “at the bottom there are remains of aquatic vegetation ... cm high.” In addition, the degree of overgrowth of aquatic vegetation in the river bed below the hydraulic station is indicated (near the banks, completely, sparsely, densely). Shoals, spits, straits, structures (dams, cofferdams, dams, bridges) are noted: it is necessary to indicate at what distance from the hydraulic station they are located.

2. Observations of the water level are carried out at the main hydrological station before and after depth measurements, as well as before and after

measuring current velocities. Recording of observation data on the height of the water level during measurements and flow measurements is carried out in the corresponding tables of the flow book.

3. Depth measurements at the hydraulic gauge are made to calculate the water cross-sectional area, as described in the section “Surveying and processing of measurement results.” Depths are measured once before measuring current velocities and are recorded in. consumption book in the “Measurements” section (in column 11). In the first and last lines, corresponding to the first: and last measuring verticals at the water's edge, c. column 0 is written “Ur.l.b.” or “Lv. p.b." (edge of the left or right bank), and in column I - depth at the edge. With steep banks, this depth may not be zero. Columns 3 and 4 are filled in only in cases where the depth is measured in an unstable channel twice: forward and backward.

4. Measurements of current velocities on verticals are usually carried out with one hydrometric turntable, sequentially moved to different points of the vertical.

Number high-speed verticals, at which current velocities are measured, with a river width of up to 50 m it is taken equal to five. When choosing locations for high-speed verticals, you should strive to ensure that they are as evenly distributed as possible across the width of the river and at the same time fall at the sharp turning points of the bottom and at the deepest point of the target. The extreme high-speed verticals should be as close to the shore as possible (as far as current speed and depth allow).

The number of points at which the flow velocity on the vertical is measured is set depending on the working depth of the high-speed vertical (Table 4).

Working depth The speed vertical, as well as on the measuring verticals, calculates the vertical distance from the bottom to the surface of the water. At a constant water level, the difference in vertical depths according to the sounding and at the time of measuring the speed in stable channel conditions should not exceed 2-3 cm at depths up to 1 m, 5 cm at depths from 1 to 3 m. If the difference is greater, the measurement should be repeat.

Table 4

Dependence of the number and location of vertical current velocity measurements on the working depth

SNiP 2.04.01-85*

Building regulations

Internal water supply and sewerage of buildings.

Internal cold and hot water supply systems

11. Devices for measuring the quantity and flow of water

11.1.* For newly constructed, reconstructed and overhauled buildings with cold and hot water supply systems, as well as only cold water supply, water consumption measuring devices should be provided - cold and hot water, the parameters of which must comply with current standards.

Water meters should be installed at the inlets of cold and hot water supply pipelines in every building and structure, in every apartment of residential buildings and on pipeline branches to shops, canteens, restaurants and other premises built-in or attached to residential, industrial and public buildings.

Installation of water meters on separate fire water supply systems is not required.

On branches to individual public and industrial buildings, as well as on connections to individual sanitary fixtures and technological equipment, water meters are installed at the customer’s request.

Hot water meters (for water temperatures up to 90°C) should be installed on the supply and circulation pipelines of hot water supply (for two-pipe networks) with the installation check valve on the circulation pipeline.

11.2. The nominal diameter of the water meter should be selected based on the average hourly water consumption for the period of consumption (day, shift), which should not exceed the operational one, taken according to the table. 4*, and check according to the instructions in clause 11.3*.

11.3.* A meter with an accepted nominal diameter must be checked:

a) to pass the calculated maximum second water flow, while the pressure loss in water meters should not exceed: 5.0 m - for vane meters and 2.5 m - for turbine meters;

b) to pass the maximum (calculated) second water flow, taking into account the supply of the calculated water flow for internal fire extinguishing, while the pressure loss in the meter should not exceed 10 m.

11.4. Pressure loss in meters, m, at a calculated second water flow rate, l/s, should be determined by the formula

where is the hydraulic resistance of the meter, taken according to table. 4*.

If it is necessary to measure water flow and it is impossible to use water meters for this purpose, other types of flow meters should be used. The selection of nominal diameter and installation of flow meters must be carried out in accordance with the requirements of the relevant technical specifications.

Table 4*

Diameter of nominal diameter of the meter, mm	Options
	water consumption, cubic m/h				maxi- small	hydraulic personal
	mini- small	exploitation tational	maxi- small	sensitivity, cubic m/h, no more	water volume per day, cubic meters	resistance counter S,

11.5.* Cold and hot water meters should be installed in a place convenient for readings and maintenance by operating personnel, in a room with artificial or natural light and air temperature not lower than 5°C.

11.6. On each side of the meters, straight sections of pipelines should be provided, the length of which is determined in accordance with state standards for water meters (vane and turbine) valves or gate valves. A drain valve should be installed between the meter and the second (according to water movement) valve or gate valve.

11.7*. Bypass line for cold water meters should be provided if:

there is one water supply entry into the building;

The water meter is not designed to handle fire-fighting water flow.

A valve sealed in the closed position should be installed on the bypass line. The valve for passing the fire-fighting water flow must be electrically driven.

The bypass line should be designed for the maximum (including fire) water flow.

An electric valve must open automatically from buttons installed at fire hydrants or from fire automatic devices. The opening of the valve must be interlocked with the start of fire pumps in case of insufficient pressure in the water supply network.

There should not be a bypass line at the hot water meter.

11.8. For residential areas, it is allowed not to provide water supply to the hot water supply system during fire extinguishing. In this case, it is necessary to ensure automatic shutdown of the water supply to this system.