A device and method for measuring multidirectional flow dynamics of small water bodies in plain areas

Abstract

The present invention discloses a device and method for multi-directional flow dynamic measurement of small water bodies in plain embankment areas. The present invention relates to the field of hydrological monitoring technology. The device includes a hollow floating annular ring; a waterproof sealing box with a built-in motor is installed in the center of the hollow floating annular ring; the waterproof sealing box is horizontally equipped with a connecting rod to connect the cleaning module and the propeller; the waterproof sealing box is vertically equipped with a vertical stretching rod; a control unit is fixed above the vertical stretching rod; and the vertical stretching rod is connected to the measuring module below. The present invention coordinates the work of each component through the control unit. The nylon brush is used to clean suspended matter on the water surface. The propeller realizes adaptive propulsion of the device. The vertical stretching rod meets the multi-depth measurement requirements. The measuring module obtains the floating body movement information in combination with the binocular vision principle, and the data can be transmitted to the cloud in real time, thereby calculating the flow velocity and direction of the small water bodies in the embankment area. The entire device has a simple structure, low maintenance cost, and a high degree of automation.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrological monitoring, and in particular to a device and method for measuring the multi-directional flow dynamics of small water bodies in plain embankment areas. Background Art

[0002] Accurately measuring the flow velocity and direction of small and micro-water bodies is one of the core tasks of hydrological monitoring. The quality of its data is directly related to the accuracy of flood evolution simulation, the efficiency of water resource optimization allocation, and the reliability of water ecological health assessment. Currently, monitoring the flow velocity and direction of small and micro-water bodies mainly relies on the following two types of equipment: the first type is contact mechanical measurement equipment, represented by rotor velocimeters. These devices calculate the flow velocity through the linear relationship between rotor speed and water velocity. These devices have simple structures but suffer from low single-point measurement efficiency and easy damage. The second type is contact acoustic measurement equipment, mainly ultrasonic Doppler velocimeters (ADVs). They invert the flow velocity vector through the sound wave reflection signal. They are easy to operate and provide relatively reliable data, but they still have significant limitations in polder applications. Algae attached to the probe surface can change the sound wave transmission characteristics.

[0003] In artificially regulated river networks such as those in plain embankments, the flow of small and micro water bodies is significantly affected by the scheduling of sluices and pumps, presenting unique hydrological and hydrodynamic characteristics of low flow velocity, multidirectionality, and strong disturbance. The presence of aquatic organisms in small and micro water bodies in embankment areas changes the acoustic characteristics of the water body and interferes with the signal. It also exacerbates physical interference and attachment during seasonal outbreaks, reducing measurement accuracy. In addition, traditional flow velocity and direction monitoring equipment for small and micro water bodies faces challenges such as low dynamic flow field analysis accuracy, high manual operation intensity, and low efficiency of repeated measurements. Therefore, it is urgent to propose a device and method for dynamic measurement of multidirectional flow in small and micro water bodies in plain embankments to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for dynamic measurement of multi-directional flow of small and micro water bodies in plain embankment areas, which can automatically monitor the multi-directional flow of small and micro water bodies, has the ability of adaptive propulsion, multi-depth measurement, and accurate calculation of flow velocity and direction, and has a simple structure, is safe and stable, and is easy to manufacture and use.

[0005] In the first aspect, the present invention provides a device for measuring the multi-directional flow dynamics of small water bodies in plain embankment areas, wherein a vertical stretching rod is provided in the center of a hollow floating ring; a control unit, a waterproof sealing box, and a measuring module are mounted on the vertical stretching rod; a motor is fixed with bolts at the bottom of the waterproof sealing box, and the left output shaft of the motor drives a nylon brush to reciprocate through a crank slider mechanism composed of a crank, a connecting rod, and a slider; the right output shaft of the motor is connected to a driving shaft through a coupling, and the driving shaft drives the left and right symmetrical propellers to rotate, thereby realizing the propulsion function of the device.

[0006] Furthermore, the control unit integrates a processor, GPS, electronic compass and 4G communication module; the vertical stretch rod realizes the lifting function through the cooperation of the guide sleeve; the counterweight lead bob is hung by a rope on the side and rear of the hollow floating ring; the solar panel is fixedly installed on the top of the vertical stretch rod through a bracket, and the solar panel supplies power to the motor through the solar cable.

[0007] Furthermore, the measuring module is made of transparent material and is connected to the vertical stretching rod through a flange; the measuring module is provided with an electric push rod base, an electric push rod, a receiving tank, a float, a limit plate and an inlet valve, and a pressure sensor; the height of the receiving tank can be consistent with the height of the limit plate and the inlet valve; an electric push rod base is welded to the side wall of the measuring module, and a retractable electric push rod is fixedly installed on the electric push rod base through a flange, the electric push rod is installed with a pressure sensor that can contact the float, and a float is provided on one side of the electric push rod; a left camera, a right camera, and a fill light are provided in the receiving tank.

[0008] Furthermore, the left camera and the right camera are connected to the control unit via a camera data transmission line; the 4G communication module in the control unit transmits the captured image data and the location information of the device to the cloud.

[0009] Furthermore, the cable signal lines of the electric push rod, limit plate, inlet valve, and pressure sensor are led out through the electric push rod base along the inner wall of the measuring module to form an integrated cable signal line; the integrated cable signal line is placed inside the vertical stretching rod and is connected to the motor and control unit respectively; the motor supplies power to each component through multiple integrated cable signal lines; the control unit sends instructions through the integrated cable signal line to control the motor to drive the nylon brush or propeller, and coordinately control the various components in the measuring module.

[0010] In a second aspect, the present invention provides a method for measuring the multidirectional flow dynamics of small water bodies in plain polder areas, and a device for measuring the multidirectional flow dynamics of small water bodies in plain polder areas, comprising:

[0011] Step 1: In the initial state, the limit plate and inlet valve are outside the receiving tank, and the electric push rod is in the retracted state; after the control unit issues a measurement command, the limit plate and inlet valve move into the receiving tank, and the float begins to move under the action of the water flow to be measured; the left and right cameras record the movement trajectory of the float and calculate the flow velocity and direction;

[0012] Step 2: When the float contacts the electric push rod and triggers its pressure sensor, the pressure sensor outputs a signal indicating the arrival of the float to the control unit; the control unit then sends an extension command to the electric push rod and the inlet valve, causing the inlet valve to extend out of the accommodating groove;

[0013] Step three, after the electric push rod extends at a uniform speed to push the float to the reset end, the control unit sends an extension command to the limit plate, and the limit plate extends out of the accommodating groove; after the limit plate extends, the electric push rod retracts, and after the water in the measuring box stabilizes, the control unit sends a measurement command again to retract the inlet valve and the limit plate into the accommodating groove, and the float begins to move with the water flow.

[0014] Furthermore, in step 1, the range of movement of the floating body is defined as a three-dimensional coordinate system [x, y, z], where: the x-axis is along the direction of the water flow; the y-axis is perpendicular to the water flow; and the z-axis is the direction of the water depth of the measurement box. The three-dimensional coordinates of the floating body are obtained by binocular vision principle, and the formula is as follows:

[0015]

[0016] Where d is the parallax, in px; is the coordinate of the left image pixel projection point; f is the camera focal length, in px; B is the dual-camera baseline distance, in m; is the horizontal coordinate of the right image pixel projection point. If the left and right cameras are coplanar, then the vertical coordinates of the left and right image pixel projection points are the same. is the coordinate of the camera principal point.

[0017] Furthermore, the flow velocity and direction calculation method in step 1 includes:

[0018] Floating body position sequence based on continuous frames , calculate the instantaneous velocity component:

[0019]

[0020] Where, For floating bodies Displacement in time, in meters; The time interval between two frames of images, in s; is the instantaneous velocity component of the floating body in the three-dimensional direction, in m / s; is the synthetic flow velocity, in m / s, indicating the actual movement rate of the floating body; is the horizontal flow angle, in radians or degrees, indicating the angle between the water flow direction and due north or the preset reference direction; The pitch angle is in radians or degrees, indicating the inclination angle of the water flow in the vertical direction.

[0021] The present invention has the following beneficial effects:

[0022] The device of the present invention integrates a nylon brush, which can effectively clean suspended matter such as duckweed and blue algae on the water surface, reducing the interference of aquatic organisms on flow velocity and direction measurement, overcoming the problems of traditional contact mechanical measuring equipment being easily entangled by water plants and algae and the probe of contact acoustic measuring equipment being easily attached by algae, thereby ensuring the accuracy and stability of the measurement.

[0023] To address the unique hydrological and hydrodynamic characteristics of small, micro-water bodies in polder areas—low flow, multidirectionality, and strong disturbances—the device features adaptive propulsion. The propeller shaft, driven by a control unit, moves the device within the micro-water body, enabling flow measurements at various locations. Furthermore, a vertical stretch rod allows the depth of the measurement module to be adjusted, meeting the requirements for measuring flow velocity and direction at multiple depths within the complex flow environment of the polder area.

[0024] The present invention realizes the automated measurement of multi-directional flows in small water bodies. The processes from float release, photographing, resetting to real-time transmission of image data are all automatically controlled by the control unit, which reduces the intensity of manual operation, improves measurement efficiency, and enables long-term unattended monitoring.

[0025] The overall structure of the device is simple, the connection method of each component is stable, and it adopts a waterproof design, which is safe and stable, reducing the maintenance cost and difficulty of use of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 This is a schematic diagram of the three-dimensional structure of a device for measuring the multi-directional flow dynamics of a small water body in a polder area provided by an example of the present invention;

[0028] Figure 2 This is a right side view of a device for measuring multi-directional flow dynamics of a small water body in a polder area provided by an example of the present invention;

[0029] Figure 3 This is a schematic diagram of the cleaning module structure in the present invention

[0030] Figure 4 This is a front view of the floating body reaching the reset end of the measuring box in the present invention;

[0031] Figure 5 It is a front view of the floating body in the present invention moving along with the water flow;

[0032] Figure 6 This is a flow chart of the multi-directional flow dynamic measurement method for small water bodies in the embankment area.

[0033] Figure 1: 1-control unit; 2-vertical stretching rod; 3-connecting rod; 301-left output shaft of motor; 302-right output shaft of motor; 4-waterproof sealing box; 401-solar cable; 402-motor; 5-propeller; 601-coupling; 602-propulsion shaft; 7-hollow floating ring; 8-plumb bob; 801-rope hanging; 9-measuring module; 10-cleaning module; 1001-fixing plate; 1002-base; 1003-crank; 1004-connecting rod ;1005-fixing bracket;1006-nylon brush;1007-slider;1008-guide rail;11-solar panel;901-left camera;902-right camera;903-electric push rod base;904-electric push rod;905-receiving tank;906-floating body;907-limiting plate;908-inlet valve;909-pressure sensor;910-fill light;911-camera data transmission line;912-integrated cable signal line;913-transparent partition. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The technical solutions provided by each embodiment of the present invention are described in detail below in conjunction with the drawings.

[0035] See also Figures 1 to 5 , the present invention provides a device for measuring the multi-directional flow dynamics of small water bodies in plain embankment areas, including: a hollow floating ring 7 for supporting the measuring device to float on the small water body, the interior of the hollow floating ring 7 is filled with lightweight foam to provide stable buoyancy; a counterweight lead bob 8 is hung on the side and rear of the hollow floating ring 7 through a rope 801 to ensure the stability of the device in water; a waterproof sealing box 4 is arranged at the center position of the side of the hollow floating ring 7, and the waterproof sealing box 4 has a built-in motor 402.

[0036] The waterproof sealing box 4 is horizontally mounted on the connecting rod 3, and the left output shaft 301 and the right output shaft 302 of the motor 402 are placed in the connecting rod 3; the fixed plate 1001 is welded to one side of the connecting rod 3; the base 1002 and the guide rail 1008 are welded to the fixed plate 1001; one end of the crank 1003 mounted on the base 1002 is coaxially fixedly connected to the left output shaft 301 of the motor, and the other end is connected to the connecting rod 1004 through a hinge; the connecting rod 1004 is fixedly connected to the slider 1007; one end of the fixing frame 1005 is fixedly connected to the slider 1007, and the other end is connected to the nylon brush 1006; the slider 1007 is a rectangular block, embedded in the guide rail 1008 and slides left and right. The left output shaft 301 of the motor drives the crank 1003 to perform circular motion. The crank 1003 pushes the slider to perform linear reciprocating sliding on the horizontal guide rail through the connecting rod 1004. At the same time, the slider 1007 transmits the motion to the nylon brush 1006 through the fixed frame 1005, realizing synchronous reciprocating sliding to clean suspended matter on the water surface.

[0037] The right output shaft 302 of the motor is connected to the propulsion shaft 602 through a coupling 601 to transmit the motor torque; two propellers 5 arranged symmetrically on the left and right are fixedly installed on the propulsion shaft 602, and the propellers 5 are fixed to the propulsion shaft 602 by key connection or welding; when the motor 402 rotates, the propellers 5 are driven to rotate through the propulsion shaft 602, so that the equipment has the ability to move in small water bodies.

[0038] A vertical stretching rod 2 is mounted on the waterproof sealing box 4 in the vertical direction. The vertical stretching rod 2 realizes the lifting function through the cooperation of the guide sleeve. By adjusting the height of the vertical stretching rod 2, accurate measurement of the flow velocity and flow direction of water at different depths in small water bodies can be achieved.

[0039] A control unit 1 is bolted to the top of the vertical stretch rod 2. It integrates a processor, GPS, an electronic compass, and a 4G communication module, enabling route planning and data encryption. A solar panel 11 is mounted on top of the vertical stretch rod 2 via a bracket. The solar panel 11 is connected to a motor 402 via a solar cable 401, providing continuous energy for the device.

[0040] The measurement module 9 is connected to the vertical stretch rod 2 via a flange. A transparent partition 913 is installed inside the measurement module 9. Together with the sidewalls, this partition 913 and the measurement module's sidewalls form a receiving groove 905. The height of the receiving groove 905 is consistent with that of the limit plate 907 and the inlet valve 908. The left camera 901, the right camera 902, and the fill light 910 are fixed to the receiving groove 905 via bolts or slots. A retractable electric push rod 904 is fixed to the sidewall of the measurement module 9 via a flange. The push rod 904 is equipped with a pressure sensor 909 that contacts a float 906. A float 906 is located on one side of the push rod 904. The measurement module 9 is made of transparent material, allowing for clear capture of the movement of the float 906. When measuring the water flow and flow direction, the inlet valve 908 and the limit plate 907 can be moved into the accommodating groove 905, and the float 906 moves with the movement of the water flow.

[0041] The left and right cameras 901 and 902 are connected to the control unit 1 via camera data transmission lines 911. The 4G communication module within the control unit 1 transmits the measured image data and the device's position information to the cloud. The signal cables for the electric push rod 904, limit plate 907, inlet valve 908, and pressure sensor 909 are routed along the inner wall of the receiving tank 905. The integrated signal cable 912 is led out through the push rod base 903. The integrated signal cable 912 passes through the inner wall of the vertical tension rod 2 and connects to the motor 402 and the control unit 1, respectively. The motor 402 supplies power to each component via multiple integrated signal cables 912. The control unit 1 issues commands to the various components of the measurement module 9 via the integrated signal cables 912. The control unit 1 issues sweeping and propulsion commands via the integrated signal cables 912, controlling the reciprocating motion of the nylon brush 1006 or the start and stop of the propeller 5 via the motor 402. The camera data transmission line 911 and the integrated cable signal line 912 are connected using waterproof connectors to ensure the stability and safety of the electrical connection in a humid environment and to prevent faults such as short circuits caused by water ingress.

[0042] like Figure 6 As shown, the flowchart of the method for measuring the multi-directional flow dynamics of small water bodies in plain polder areas provided by the present invention shows the complete application process of the present invention from measurement preparation to result acquisition, which is as follows:

[0043] During the measurement preparation phase, the nylon brush in the cleaning element is used to remove suspended matter from the water surface to prevent interference with the measurement. The position and orientation of the measuring device are determined by GPS and an electronic compass to ensure measurement accuracy and consistency. The depth of the measuring module is adjusted with the help of a vertical stretch rod to accommodate water flow measurements at different depths.

[0044] During the measurement phase: After a measurement command is issued, the inlet valve and limit plate move into the reservoir, releasing the float. The float begins to move under the influence of the water flow, and the camera records its motion trajectory. Using binocular vision, the 3D coordinates of the float are calculated, and the flow velocity and direction are then calculated, generating a 3D velocity vector diagram.

[0045] During the reset phase, when the movement of the float triggers the pressure sensor, the control unit issues a reset command, and the electric push rod pushes the float to reset. The range of the three-dimensional coordinate system at the reset end of the float is defined as [L, y, z]; then the inlet valve and the limit plate extend out of the accommodating groove, completing a measurement cycle. After the electric push rod resets, it waits for the next measurement command.

[0046] The range of the floating body is defined as a three-dimensional coordinate system [x, y, z], where the x-axis is along the water flow direction; the y-axis is perpendicular to the water flow direction; and the z-axis is the water depth direction of the measurement box, which is determined by the lifting position of the vertical stretch rod. The three-dimensional coordinates of the floating body are obtained through the binocular vision principle, and the formula is as follows:

[0047]

[0048] Where d is the parallax, in px; is the coordinate of the left image pixel projection point; f is the camera focal length, in px; B is the dual-camera baseline distance, in m; is the horizontal coordinate of the right image pixel projection point. If the left and right cameras are coplanar, then the vertical coordinates of the left and right image pixel projection points are the same. is the coordinate of the camera principal point.

[0049] Specifically, the flow velocity and direction calculation method includes:

[0050] Floating body position sequence based on continuous frames , calculate the instantaneous velocity component:

[0051] Where, For floating bodies Displacement in time, in meters; The time interval between two frames of images, in s; is the instantaneous velocity component of the floating body in the three-dimensional direction, in m / s; is the synthetic flow velocity, in m / s, indicating the actual movement rate of the floating body; is the horizontal flow angle, in radians or degrees, indicating the angle between the water flow direction and due north or the preset reference direction; The pitch angle is in radians or degrees, indicating the inclination angle of the water flow in the vertical direction.

[0052] Finally, it should be noted that the above is only the preferred technical solution and application process of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications, replacements, improvements, etc. of the present invention should all be included in the scope of protection of the present invention.

Claims

1. A device for measuring the multi-directional flow dynamics of small water bodies in plain embankment areas, characterized in that: A vertical stretching rod (2) is provided at the center of the hollow floating annular ring (7); a control unit (1), a waterproof sealing box (4), and a measuring module (9) are mounted on the vertical stretching rod (2); a motor (402) is fixed to the bottom of the waterproof sealing box (4) by bolts, and a left motor output shaft (301) of the motor (402) drives a nylon brush (1006) to reciprocate through a crank slider mechanism composed of a crank (1003), a connecting rod (1004), and a slider (1007); a right motor output shaft (302) of the motor (402) is connected to a driving shaft (602) through a coupling (601), and the driving shaft (602) drives the left and right symmetrical propellers (5) to rotate, thereby realizing the propulsion function of the device; The control unit (1) integrates a processor, a GPS, an electronic compass, and a 4G communication module; the vertical stretch rod (2) realizes a lifting function through cooperation with a guide sleeve; a counterweight plumb bob (8) is hung on the side and rear of the hollow floating annular ring (7) through a rope hanging (801); a solar panel (11) is fixedly mounted on the top of the vertical stretch rod (2) through a bracket, and the solar panel (11) supplies power to the motor (402) through a solar cable (401); The measuring module (9) is made of a transparent material and is connected to the vertical stretching rod (2) via a flange. The measuring module (9) is provided with an electric push rod base (903), an electric push rod (904), a receiving groove (905), a floating body (906), a limit plate (907), an inlet valve (908), and a pressure sensor (909). The height of the receiving groove (905) can be consistent with the height of the limit plate (907) and the inlet valve (908). The measuring module (9) is welded with an electric push rod base (903) on the side wall, and a retractable electric push rod (904) is fixedly mounted on the electric push rod base (903) via a flange. The electric push rod (904) is provided with a pressure sensor (909) capable of contacting the floating body (906). A floating body (906) is provided on one side of the electric push rod (904). A left camera (901), a right camera (902), and a fill light (910) are provided in the receiving groove (905).

2. The device for measuring multi-directional flow dynamics of small water bodies in plain embankment areas according to claim 1, characterized in that: The left camera (901) and the right camera (902) are connected to the control unit (1) via a camera data transmission line (911); the 4G communication module in the control unit (1) transmits the captured image data and the location information of the device to the cloud.

3. The device for measuring multi-directional flow dynamics of small water bodies in plain embankment areas according to claim 2, characterized in that: The cable signal lines of the electric push rod (904), the limit plate (907), the inlet valve (908), and the pressure sensor (909) are led out of the integrated cable signal line (912) along the inner wall of the measuring module (9) through the electric push rod base (903); the integrated cable signal line (912) is placed inside the vertical stretching rod (2) and is connected to the motor (402) and the control unit (1) respectively; the motor (402) supplies power to each component through multiple strands of the integrated cable signal line (912); the control unit (1) issues instructions through the integrated cable signal line (912) to control the motor (402) to drive the nylon brush (1006) or the propeller (5), and to coordinately control the various components in the measuring module (9).

4. A method for measuring the multidirectional flow dynamics of small water bodies in plain polder areas, applied to the device for measuring the multidirectional flow dynamics of small water bodies in plain polder areas according to claim 3, characterized in that: include: Step 1: In the initial state, the limit plate (907) and the inlet valve (908) are outside the receiving groove (905), and the electric push rod (904) is in a retracted state; after the control unit (1) issues a measurement command, the limit plate (907) and the inlet valve (908) move into the receiving groove (905), and the float (906) starts to move under the action of the water flow to be measured; the left camera (901) and the right camera (902) record the movement trajectory of the float and calculate the flow velocity and direction; Step 2: When the float (906) contacts the electric push rod (904) and triggers its pressure sensor (909), the pressure sensor (909) outputs a signal indicating the arrival of the float to the control unit (1); then the control unit (1) sends an extension command to the electric push rod (904) and the inlet valve (908), and the inlet valve (908) extends out of the accommodating groove (905); In step three, the electric push rod (904) extends at a uniform speed to push the float (906) to the reset end, and the control unit (1) sends an extension command to the limit plate (907), and the limit plate (907) extends out of the accommodating groove (905); after the limit plate (907) extends, the electric push rod (904) retracts, and after the water in the measuring box stabilizes, the control unit (1) sends a measurement command again, so that the inlet valve (908) and the limit plate (907) are retracted into the accommodating groove (905), and the float (906) begins to move with the water flow.

5. The method for measuring multidirectional flow dynamics of small water bodies in plain embankment areas according to claim 4, characterized in that: In step 1, the range of the floating body is defined as a three-dimensional coordinate system [x, y, z], where the x-axis is along the water flow direction; the y-axis is perpendicular to the water flow direction; and the z-axis is the direction of the water depth in the measurement box. The three-dimensional coordinates of the floating body are obtained by binocular vision principle, and the formula is as follows: Where d is the parallax, in px; is the coordinate of the left image pixel projection point; f is the camera focal length, in px; B is the dual-camera baseline distance, in m; is the horizontal coordinate of the right image pixel projection point. If the left and right cameras are coplanar, then the vertical coordinates of the left and right image pixel projection points are the same. is the coordinate of the camera principal point.

6. A method for measuring multidirectional flow dynamics of small water bodies in plain embankment areas according to claim 4, characterized in that: The flow velocity and direction calculation method in step 1 includes: Floating body position sequence based on continuous frames , calculate the instantaneous velocity component: Where, For floating bodies Displacement in time, in meters; The time interval between two frames of images, in s; is the instantaneous velocity component of the floating body in the three-dimensional direction, in m / s; is the synthetic flow velocity, in m / s, indicating the actual movement rate of the floating body; is the horizontal flow angle, in radians or degrees, indicating the angle between the water flow direction and due north or the preset reference direction; The pitch angle is in radians or degrees, indicating the inclination angle of the water flow in the vertical direction.

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