An irregular river channel cross-section flow measurement device and method

Abstract

An irregular river channel cross-section flow measurement device and method, comprising a computer, a signal receiver, a left support and a right support. The left support and the right support are respectively arranged on the left and right sides of the river channel. A cable is provided between the left support and the right support, and the cable is perpendicular to the river water flow direction. A rotary connection seat for fixedly installing a sonic depth finder is fixedly arranged on the cable, or a movable pulley assembly for fixedly connecting a sonic depth finder and a radar speedometer is slidably arranged on the cable. The sonic depth finder and the radar speedometer transmit signals to the signal receiver through wireless communication, and the signal receiver is communicatively connected to the computer. The principle of the present invention is scientific and the operation is convenient. By using the rotary connection seat in cooperation with the sonic depth finder, the small-scale concave and convex conditions of the river channel cross-section can be better understood, and the river channel cross-section can be correctly simulated according to the angle and distance, and the test data is more accurate.

Description

Technical Field

[0001] The present invention belongs to the technical field related to hydrology and geology, and particularly relates to a device and method for measuring the flow rate of an irregular river channel cross-section. Background Art

[0002] At present, the main method for measuring the flow rate of large floods in the north is still the float method. Due to the large slope and high flow velocity of the northern rivers, especially for some small and medium-sized rivers with poor vegetation in the basin, the runoff concentration time is short, the rainstorm flood process rises and falls steeply, the peak duration is short, and the impact force of the water flow on the lead fish and current meter is large. Therefore, it is particularly important to measure the cross-section flow rate in some special environments.

[0003] Flow rate data plays an extremely important role, covering various aspects such as flood control safety, hydrological and hydraulic calculations, and water resource evaluation. Therefore, river flow rate measurement is an important part of hydrological work. Every year, a large amount of manpower and material resources are consumed to complete the measurement tasks. In order to reduce the workload of flow rate measurement, hydrological workers have been looking for methods to reduce the number of flow rate measurement times for a long time.

[0004] There have been some studies on the flow rate of the cross-section of flowing water in the prior art. For example, a river channel cross-section flow meter for non-contact radar flow measurement with the application number 201810948626.3 conducts cross-section measurements at a certain distance interval on the river channel cross-section where the radar probe measurement point is located. Based on the measured cross-section data, cross-section polynomial curve fitting is performed, and according to the probe position, measured water level, surface flow velocity, and river bed roughness, combined with the Manning formula of hydraulics, the water surface slope of the river channel cross-section is calculated. Then, based on the principle of natural river channel flow rate calculation in hydraulics, a certain number of vertical lines are selected to evenly divide the river channel cross-section, and the water depth of each vertical line and the average flow velocity corresponding to the vertical line are calculated in turn. Then, virtual vertical lines are drawn at the midpoints of each vertical line interval. Several vertical virtual lines, the cross-section fitting curve, and the river water level line form several irregular polygons. The area of each polygon is calculated in turn. Finally, the area weighted method is used to calculate the large cross-section flow rate of the river channel.

[0005] However, this solution has many defects, specifically including: the flow velocity measured by the radar flow meter is the surface flow velocity, not the real flow velocity. There is a water surface flow velocity coefficient between the real flow velocity and the surface flow velocity. It is necessary to correct the surface flow velocity, and use the corrected flow velocity to calculate the large cross-section flow rate of the river channel by the flow velocity area method, so that the experimental results can be more accurate.

[0006] The river channel cross-section flow meter for non-contact radar flow measurement conducts cross-section measurements at a certain distance interval, records the elevation coordinates, and draws the measured map of the river cross-section. It cannot correctly simulate the concave and convex conditions of a small part of the river channel cross-section and the measurement times are too many.

[0007] Therefore, it is necessary to design a device and method with relatively simple structure and high precision to measure the flow rate of irregular cross-sections. Summary of the Invention

[0008] The present invention aims to solve the deficiencies in the prior art and provides an irregular river cross-section flow measurement device and method with scientific principle, convenient operation, and high precision of test results.

[0009] To solve the above technical problems, the present invention adopts the following technical solution: An irregular river cross-section flow measurement device includes a computer, a signal receiver, a left support and a right support. The left support and the right support are respectively arranged on the left and right sides of the river. A cable is provided between the left support and the right support, perpendicular to the river flow direction. A rotary connection seat for fixedly installing a sonic depth finder is fixed on the cable, or a movable pulley assembly for fixedly connecting a sonic depth finder and a radar speedometer is slidably arranged on the cable. The sonic depth finder and the radar speedometer transmit signals to the signal receiver through wireless communication, and the signal receiver is communicatively connected to the computer.

[0010] The rotary connection seat includes a fixed plate and a movable plate. Two upper and lower corresponding left connection holes are opened on the left side of the fixed plate, and two upper and lower corresponding right connection holes are opened on the right side of the fixed plate. The two left connection holes are fixedly connected to the cable through a set of U-bolts and nuts, and the two right connection holes are fixedly connected to the cable through another set of U-bolts and nuts. A bearing seat is fixedly arranged in the middle of the side surface of the fixed plate facing away from the cable. A bearing is installed in the bearing seat, and the outer circle of the bearing is in interference fit with the inner circle of the bearing seat. The inner circle of the bearing is press-fitted with a rotating shaft, and the outer end of the rotating shaft is fixedly connected to one side surface of the movable plate. A 360° angular scale is provided along the circumferential direction on the end surface of the outer circle of the bearing, and a pointer for pointing to the angular scale is provided on the outer circle of the rotating shaft. A plurality of mounting holes are opened on the movable plate, and the sonic depth finder is fixedly connected to the movable plate through screws passing through the mounting holes.

[0011] A measurement method for an irregular river cross-section flow measurement device includes the following steps:

[0012] (1) Select a river, erect a left support and a right support on the left and right sides of the river respectively, set up a tensioned cable between the left support and the right support. First, connect the fixed plate of the rotary connection seat to the middle position in the length direction of the cable through two sets of U-bolts and nuts, and then fix the sonic depth finder to the movable plate of the rotary connection seat through screws. Use a GPS positioning device and a total station on the river bank to record the three-dimensional coordinates of the probe of the sonic depth finder.

[0013] (2) Point the probe of the acoustic depth sounder towards the left bank of the river channel, rotate the movable plate, which drives the probe of the acoustic depth sounder to rotate. Rotate 10° or less each time from the left bank until 180° to the right bank; record the rotation angle each time by the position where the pointer corresponds to the angle scale. The acoustic depth sounder transmits the numerical signal of the distance to the bottom boundary of the river channel cross-section to the computer, and the computer generates the river channel cross-section curve and fits the shape of the river channel surface into a mathematical expression;

[0014] (3) Make a scaled-down river curve model of the obtained river channel cross-section curve shape with a scale factor of t. Combine the designed wetted perimeter measuring device to calculate the wetted perimeter length;

[0015] (4) Remove the rotating connector from the cable, and also remove the acoustic depth sounder connected to the rotating connector. Then hang the movable pulley assembly on the cable, install the acoustic depth sounder on the movable pulley assembly, manually drive the boat under the cable, move the movable pulley assembly so that the acoustic depth sounder moves along the cable. Divide the length of the cable from the left side to the right side of the river channel into 30 - 40 points evenly and mark them. Move the movable pulley assembly to each point from left to right in turn, and the acoustic depth sounder measures the distance from this point to the bottom of the river channel, that is, the measured cross-section depth of the river channel at this point;

[0016] (5) Remove the acoustic depth sounder, install a radar speedometer on the movable pulley assembly. The radar speedometer should be more than 0.5 m away from the water surface. According to the 30 - 40 points marked on the cable in step (4), move the movable pulley assembly to the position of the marked point, and the radar speedometer measures the surface velocity V of the position where each point is orthogonally projected on the river surface in turn 表 ;

[0017] (6) Calculate the cross-section water surface velocity coefficient R;

[0018] (7) Combine the river channel cross-section curve and the interval positions of the perpendiculars from each point to the bottom of the river channel to divide the river channel cross-section into multiple small cross-sections. Select the small cross-sections in turn. Take the starting point of the first small cross-section on the left as the coordinate origin, select an appropriate number of coordinates on the small cross-section curve, record (X1, Y1), (X2, Y2), etc. in turn, and use the formula for calculating the area of a polygon with coordinate values ;

[0019] (8) According to the calculation principle of the natural river channel flow in hydraulics, using the velocity-area weighted method, multiply the areas S of each polygon 任意 by the measured surface velocity V 表 and the cross-section velocity coefficient R and then sum them up respectively, then the calculation of the river channel cross-section flow Q can be completed. The calculation formula is ; where m is the number of divided polygons.

[0020] Step (3) is specifically as follows: The wetted perimeter measuring device uses several needles. The needles used are 40 mm in length and 0.3 mm in diameter. These needles of such specifications are arranged at equal intervals, and the distance d between two adjacent needles is 0.1 mm. Press the river curve model onto the tips of the needles arranged at equal intervals. The position where the tip of the first needle touches the river curve model remains unchanged and is set as a reference, the origin position. The tips of the needles will reflect the shape of this curved surface. Since the distance d between the tips of the needles is small, the length L of the river curved surface is approximately equal to the length h of the needle relative to the reference needle at the origin. Add up the relative lengths h of each needle, and the sum obtained is the wetted perimeter length of the river curve of the scaled-down model. Multiply it by the scale factor t to obtain the actual wetted perimeter length of the river channel.

[0021] The specific calculation process of step (6) is as follows: Remove the radar speedometer and install a high-precision single-point flowmeter on the movable pulley assembly. According to the water depth of the vertical lines at different marked points, select the number of precise flow measurement points. Combine with the calculation formula for the average flow velocity on the vertical line to calculate the average flow velocity on the vertical line. Taking the starting measurement point as the origin, with the surface flow velocity as the abscissa and the average flow velocity as the ordinate, plot a graph. Using image fitting, the slope of the graph can be obtained, which is the cross-sectional water surface flow velocity coefficient R.

[0022] Selection of the number of points for checking the average flow velocity on the vertical line:

[0023] 1) When the water depth is less than 1.5 m, the one-point method at 0.6 or 0.5 relative water depth can be used;

[0024] 2) When the water depth is greater than or equal to 1.5 m and less than 3.0 m, the two-point method at 0.2 and 0.8 relative water depth can be used;

[0025] 3) When the water depth is greater than or equal to 3.0 m and less than 5.0 m, the three-point method can be used;

[0026] 4) When the water depth is greater than or equal to 5.0 m, the six-point method is used;

[0027] Calculation formula for the average flow velocity on the vertical line:

[0028] 。

[0029] With the above technical solution, the present invention provides an irregular river cross-section flow measurement device and a measurement method. On the river cross-section, a rotary connecting seat with angle measurement is placed, and an acoustic depth finder is installed on the rotary connecting seat. Based on the distance and angle measurement from the acoustic depth finder to the measured cross-section interface, combined with the measurement of the coordinates of the acoustic depth finder itself, a schematic diagram of the river cross-section is drawn. According to the coordinates of the river cross-section curve and the formula for calculating the polygon area by combining coordinate values, the area of any river cross-section can be calculated. A scaled-down river curve model is made from the obtained river curve shape, and combined with the designed wetted perimeter measurement device and the scale factor of the model reduction, the wetted perimeter length can be calculated. On the river cross-section, at a certain distance interval, the cross-section velocity measurement and depth measurement are carried out with the help of a radar current meter and an acoustic depth finder. The measured data are the surface velocity of the river cross-section and the depth at a certain vertical line respectively. By plotting the average velocity measured by a single-point current meter and the surface velocity measured by a radar current meter, the surface velocity coefficient is obtained for velocity correction. Using the corrected velocity and the velocity-area method, the large cross-section flow of the river is calculated.

[0030] In summary, the beneficial effects of the present invention are as follows:

[0031] (1) There is a surface velocity coefficient between the true velocity and the surface velocity. It is necessary to correct the surface velocity, and use the corrected velocity and the velocity-area method to calculate the large cross-section flow of the river, which can make the experimental results more accurate.

[0032] (2) In this design, the wetted perimeter measurement device is designed using the differential principle, making the wetted perimeter measurement result more accurate.

[0033] (3) Using a rotary connecting seat in cooperation with an acoustic depth finder can better understand the small-scale concave and convex conditions of the river cross-section, and correctly simulate the river cross-section with the change of angle and distance;

[0034] (4) The adopted rotary connecting seat is convenient for installing the acoustic depth finder and also for connecting the cable. The rotation angle of the acoustic current meter can be determined by rotating the inner ring of the rotating shaft and pointing the pointer to the angle scale, thereby improving the measurement accuracy. Description of the Drawings

[0035] Figure 1 It is a schematic diagram of the present invention with an acoustic depth finder arranged on the cable;

[0036] Figure 2 It is a schematic diagram of the present invention with a radar current meter arranged on the cable;

[0037] Figure 3 is Figure 1 The enlarged view of the rotary connecting seat in

[0038] Figure 4Schematic diagram of a U-bolt connecting the fixing plate and the cable

[0039] Figure 5 Schematic diagram of a screw connecting the acoustic depth sounder and the movable plate

[0040] Figure 6 Working principle diagram of the wetted perimeter measuring device Detailed implementation mode

[0041] As Figures 1-6 shown, an irregular river channel cross-section flow measurement device of the present invention includes a computer 1, a signal receiver 2, a left support 3 and a right support 4. The left support 3 and the right support 4 are respectively arranged on the left and right sides of the river channel 5. A cable 6 is arranged between the left support 3 and the right support 4. The cable 6 is perpendicular to the river water flow direction. A rotary connection seat for fixedly installing the acoustic depth sounder 7 is fixedly arranged on the cable 6, or a movable pulley assembly 9 for fixedly connecting the acoustic depth sounder 7 and the radar speedometer 8 is slidably arranged. The acoustic depth sounder 7 and the radar speedometer 8 transmit signals to the signal receiver 2 through wireless communication, and the signal receiver 2 is communicatively connected to the computer 1.

[0042] The rotary connection seat includes a fixing plate 10 and a movable plate 11. Two upper and lower corresponding left connection holes 12 are opened on the left side of the fixing plate 10, and two upper and lower corresponding right connection holes 13 are opened on the right side of the fixing plate 10. The two left connection holes 12 are fixedly connected to the cable 6 through a set of U-bolts 14 and nuts, and the two right connection holes 13 are fixedly connected to the cable 6 through another set of U-bolts 14 and nuts. A bearing seat 15 is fixedly arranged in the middle of the side surface of the fixing plate 10 facing away from the cable 6. A bearing 16 is installed in the bearing seat 15. The outer circle of the bearing 16 is in interference fit with the inner circle of the bearing seat 15. A rotating shaft 17 is press-fitted in the inner circle of the bearing 16. The outer end of the rotating shaft 17 is fixedly connected to one side surface of the movable plate 11. A 360° angular scale is arranged along the circumferential direction on the end surface of the outer circle of the bearing 16. A pointer 18 for pointing to the angular scale is arranged on the outer circle of the rotating shaft 17. A plurality of mounting holes 19 are opened on the movable plate 11, and the acoustic depth sounder 7 is fixedly connected to the movable plate 11 through a screw 20 passing through the mounting holes 19.

[0043] The movable pulley assembly 9 is a conventional existing structure and will not be described in detail. The acoustic depth sounder 7 and the radar speedometer 8 can also be fixed on the movable pulley assembly 9 by bolts.

[0044] A measurement method for an irregular river channel 5 cross-section flow measurement device includes the following steps:

[0045] (1) Select a river channel 5, erect a left support 3 and a right support 4 on the left and right sides of the river channel 5 respectively, and set up a tensioned cable 6 between the left support 3 and the right support 4. First, use two sets of U-bolts 14 and nuts to connect the fixed plate 10 of the rotary connector to the middle position in the length direction of the cable 6, and then fix the acoustic depth sounder 7 to the movable plate 11 of the rotary connector through screws 20. Use a GPS positioning device and a total station on the bank of the river channel 5 to record the three-dimensional coordinates of the probe of the acoustic depth sounder 7.

[0046] (2) Turn the probe of the acoustic depth sounder 7 towards the left bank of the river channel 5, rotate the movable plate 11, and the movable plate 11 drives the probe of the acoustic depth sounder 7 to rotate. Rotate 10° or less each time from the left bank until 180° is rotated to the right bank; record the rotation angle each time through the position where the pointer 18 corresponds to the angle scale. The acoustic depth sounder 7 transmits the numerical signal of the distance to the bottom boundary of the cross-section of the river channel 5 to the computer 1, and the computer 1 generates the cross-section curve of the river channel 5 and fits the surface shape of the river channel 5 into a mathematical expression.

[0047] (3) Make a proportionally reduced river curve model of the obtained cross-section curve shape of the river channel 5, with a scale factor of t, and combine it with the designed wetted perimeter measuring device to calculate the wetted perimeter length.

[0048] (4) Remove the rotary connector from the cable 6, and also remove the acoustic depth sounder 7 connected to the rotary connector. Then hang the movable pulley assembly 9 on the cable 6, install the acoustic depth sounder 7 on the movable pulley assembly 9, manually drive a boat under the cable 6, move the movable pulley assembly 9, so that the acoustic depth sounder 7 moves along the cable 6. Divide the length of the cable 6 from the left side to the right side of the river channel 5 into 30 - 40 points evenly and mark them. Move the movable pulley assembly 9 to each point in turn from left to right, and the acoustic depth sounder 7 measures the distance from this point to the bottom of the river channel 5, that is, the measured cross-section depth of the river channel 5 at this point.

[0049] (5) Remove the acoustic depth sounder 7, install a radar speedometer 8 on the movable pulley assembly 9. The distance between the radar speedometer 8 and the water surface should be greater than 0.5 m. According to the 30 - 40 points marked on the cable 6 in step (4), move the movable pulley assembly 9 to the position of the marked points, and the radar speedometer 8 measures the surface velocity V of the position where each point is projected orthogonally on the river surface in turn. 表 ;

[0050] (6) Calculate the cross-section water surface velocity coefficient R.

[0051] (7) The cross-section of the river channel 5 can be divided into multiple small cross-sections by combining the cross-section curve of the river channel 5 and the interval positions of the perpendiculars from each point to the bottom of the river channel 5. Select the small cross-sections in sequence. Taking the starting point of the leftmost first small cross-section as the coordinate origin, select an appropriate number of coordinates on the curve of this small cross-section, and record (X1, Y1), (X2, Y2), etc. in sequence. Use the formula for calculating the area of a polygon with the coordinate values. ;

[0052] (8) According to the principle of calculating the flow rate of a natural river channel 5 in hydraulics, using the velocity-area weighted method, multiply the area S of each polygon 任意 by the measured surface velocity V 表 and the cross-section velocity coefficient R, and then sum them up respectively, then the calculation of the flow rate Q of the cross-section of the river channel 5 can be completed. The calculation formula is ; where m is the number of divided polygons.

[0053] Step (3) is specifically as follows: The wetted perimeter measuring device uses several needles. The length of the needles used is 40 mm and the diameter is 0.3 mm. Arrange these needles at equal intervals. The distance d between adjacent two needles is 0.1 mm. Press the river curve model on the tips of the needles arranged at equal intervals. The position where the tip of the first needle touches the river curve model remains unchanged and is set as a reference, the origin position. The tips of the needles will reflect the shape of this curved surface. Since the distance d between the tips of the needles is small, the length L of the river curved surface is approximately equal to the length h of the needle relative to the reference needle at the origin. Accumulate the relative lengths h of each needle, and the sum obtained is the wetted perimeter length of the river curve of the reduced model. Then multiply it by the scale factor t to obtain the true wetted perimeter length of the river channel 5.

[0054] The specific calculation process of step (6) is as follows: Remove the radar speedometer 8, install a high-precision single-point flow velocity meter on the movable pulley assembly 9. According to the water depth of the perpendiculars at different marked points, select the number of fine-measured flow velocity measurement points. Combine the calculation formula of the average flow velocity on the perpendicular, calculate the average flow velocity on the perpendicular. Taking the starting measurement point as the origin, the surface velocity as the abscissa, and the average flow velocity as the ordinate, make a graph. Using image fitting, the slope of the image can be obtained, which is the cross-section water surface velocity coefficient R.

[0055] Selection of the number of points for checking the average flow velocity on the perpendicular:

[0056] 1) When the water depth is less than 1.5 m, the one-point method with a relative water depth of 0.6 or 0.5 can be adopted;

[0057] 2) When the water depth is greater than or equal to 1.5 m and less than 3.0 m, the two-point method with relative water depths of 0.2 and 0.8 can be adopted;

[0058] 3) When the water depth is greater than or equal to 3.0 m and less than 5.0 m, the three-point method can be adopted;

[0059] 4) When the water depth is greater than or equal to 5.0 m, the six-point method is adopted;

[0060] Formula for calculating the average velocity at a vertical line:

[0061] 。

[0062] The above embodiments illustrate the basic trimming principle and characteristics of the present invention. However, the above only illustrates the preferred embodiments of the present invention and is not limited by the described embodiments. Those of ordinary skill in the art, inspired by this patent and without departing from the purpose of the present invention and the scope protected by the claims, can also make many forms of deformation and improvement, which are all within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be subject to the appended claims.

Claims

1. An irregular river channel cross-section flow measurement device, characterized in that: It includes a computer, a signal receiver, a left support and a right support. The left support and the right support are respectively arranged on the left and right sides of the river channel. A cable is provided between the left support and the right support. The cable is perpendicular to the flowing direction of the river water. A rotary connecting seat for fixedly installing a sonic depth finder is fixedly provided on the cable, or a movable pulley assembly for fixedly connecting a sonic depth finder and a radar speedometer is slidably provided on the cable. The sonic depth finder and the radar speedometer transmit signals to the signal receiver through wireless communication, and the signal receiver is communicatively connected to the computer; The rotary connecting seat includes a fixed plate and a movable plate. Two upper and lower corresponding left connection holes are opened on the left side of the fixed plate, and two upper and lower corresponding right connection holes are opened on the right side of the fixed plate. The two left connection holes are fixedly connected to the cable through a set of U-shaped bolts and nuts, and the two right connection holes are fixedly connected to the cable through another set of U-shaped bolts and nuts. A bearing seat is fixedly provided in the middle of the side surface of the fixed plate facing away from the cable. A bearing is installed in the bearing seat. The outer circle of the bearing is in interference fit with the inner circle of the bearing seat. The inner circle of the bearing is interference-fitted with a rotating shaft. The outer end of the rotating shaft is fixedly connected to one side surface of the movable plate. A 360° angular scale is provided along the circumferential direction on the end surface of the outer ring of the bearing. A pointer for pointing to the angular scale is provided on the outer circle of the rotating shaft. A plurality of mounting holes are opened on the movable plate, and the sonic depth finder is fixedly connected to the movable plate through screws passing through the mounting holes.

2. The measurement method of an irregular river channel cross-section flow measurement device as described in claim 1, characterized in that: It includes the following steps: (1) Select a river channel, erect a left support and a right support on the left and right sides of the river channel respectively, set up a tensioned cable between the left support and the right support. First, connect the fixed plate of the rotary connecting seat to the middle position in the length direction of the cable through two sets of U-shaped bolts and nuts, and then fix the sonic depth finder to the movable plate of the rotary connecting seat through screws. Use a GPS positioning device and a total station on the bank of the river channel to record the three-dimensional coordinates of the probe of the sonic depth finder; (2) Point the probe of the sonic depth finder towards the left bank of the river channel, rotate the movable plate, and the movable plate drives the probe of the sonic depth finder to rotate. Rotate 10° or less each time from the left bank until 180° to the right bank; record the rotation angle each time through the position where the pointer corresponds to the angular scale. The sonic depth finder transmits the numerical signal of the distance to the bottom boundary of the river channel section to the computer, and the computer generates a river channel section curve and fits the shape of the river channel surface into a mathematical expression; (3) Make a scaled-down river curve model of the obtained river channel section curve shape, with a scale factor of t. Combine the designed wetted perimeter measuring device to calculate the wetted perimeter length; (4) Remove the rotary connecting seat from the cable, and also remove the sonic depth finder connected to the rotary connecting seat. Then hang the movable pulley assembly on the cable, install the sonic depth finder on the movable pulley assembly, manually drive a boat under the cable, move the movable pulley assembly to make the sonic depth finder move along the cable. Divide the length of the cable from the left side to the right side of the river channel into 30 - 40 points evenly and mark them. Move the movable pulley assembly to each point in turn from left to right, and the sonic depth finder measures the distance from this point to the bottom of the river channel, that is, the measured cross-section depth of the river channel at this point; (5) Remove the acoustic sounder and install a radar speedometer on the movable pulley assembly. The distance between the radar speedometer and the water surface should be greater than 0.5 m. Move the movable pulley assembly to the positions of the marked points according to the 30 - 40 points marked on the cable in step (4), and the radar speedometer measures the surface velocity V of the position where the orthographic projection of each point is on the river surface in turn. 表 ; (6) Calculate the cross-section water surface velocity coefficient R; (7) The river channel cross-section can be divided into multiple small cross-sections by combining the river channel cross-section curve and the interval positions of the perpendicular lines from each point to the bottom of the river channel. Select the small cross-sections in sequence. Taking the starting point of the first small cross-section on the left as the coordinate origin, select an appropriate number of coordinates on the curve of this small cross-section, and record (X1, Y1), (X2, Y2), ……, (X n , Y n ) in sequence. Use the formula for calculating the area of a polygon with the coordinate values ; (8) According to the principle of natural river flow calculation in hydraulics, using the velocity-area weighted method, multiply the area S of each polygon 任意 by the measured surface velocity V 表 and the cross-sectional velocity coefficient R, and then sum them up respectively, then the calculation of the river cross-sectional flow Q can be completed. The calculation formula is ; where m is the number of divided polygons.

3. The measuring method of an irregular river channel cross-section flow measuring device according to claim 2, characterized in that: Step (3) is specifically as follows: The wetted perimeter measuring device uses several needles. The needles used are 40 mm in length and 0.3 mm in diameter. These needles of such specifications are arranged at equal intervals, and the distance d between adjacent needles is 0.1 mm. Press the river curve model onto the tips of the needles arranged at equal intervals. The position where the tip of the first needle touches the river curve model remains unchanged and is set as a reference, the origin position. The tips of the needles will reflect the shape of the surface. Since the distance d between the tips of the needles is small, the length L of the river surface is approximately equal to the length h of the needle relative to the reference needle at the origin. Add up the relative lengths h of each needle, and the sum obtained is the wetted perimeter length of the river curve of the reduced model. Multiply it by the scale factor t to obtain the actual wetted perimeter length of the river channel.

4. The measuring method of an irregular river channel cross-section flow measuring device according to claim 2 or 3, characterized in that: The specific calculation process of step (6) is as follows: Remove the radar speedometer and install a single-point flowmeter with higher precision on the movable pulley assembly. According to the water depth of the vertical lines at different marked points, select the number of fine-measured flow velocity measurement points. Combine with the calculation formula of the average flow velocity on the vertical line to calculate the average flow velocity on the vertical line. Using the starting measurement point as the origin, the surface flow velocity as the abscissa, and the average flow velocity as the ordinate, plot a graph. By using image fitting, the slope of the graph can be obtained, which is the cross-sectional water surface flow velocity coefficient R.

5. The measuring method of an irregular river channel cross-section flow measuring device according to claim 4, characterized in that: Selection of the number of points for checking the average flow velocity on the vertical line: 1) When the water depth is less than 1.5 m, the one-point method at 0.6 or 0.5 relative water depth can be used; 2) When the water depth is greater than or equal to 1.5 m and less than 3.0 m, the two-point method at 0.2 and 0.8 relative water depth can be used; 3) When the water depth is greater than or equal to 3.0 m and less than 5.0 m, the three-point method can be used; 4) When the water depth is greater than or equal to 5.0 m, the six-point method is used; Calculation formula for the average flow velocity on the vertical line: 。

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