Underwater profile density measurement system and method

Abstract

The present invention relates to the technical field of marine hydrological monitoring, and in particular to an underwater profile density measurement system and method. The system comprises a survey vessel, a vessel anchor, a steel wire rope, rope guide devices, a parameter measurement device, a measurement and control transmission cable, and a data analysis system. The method comprises: connecting a vessel anchor to a steel wire rope, and then dropping the vessel anchor to a water bottom for anchoring and fixing; enabling a parameter measurement device to enter water along with a measurement and control transmission cable and to maintain movable connection with the steel wire rope; successively pulling the measurement and control transmission cable according to equally spaced markers to move upwards along the steel wire rope from an anchor point, and collecting two water pressure values at different depths and an attitude angle value measured by the parameter measurement device underwater; storing the collected data in a data analysis system, and on the basis of a built-in algorithm, obtaining the density of water around the parameter measurement device; and when the parameter measurement device moves upwards from the anchor point and leaves the water, performing integral processing on the measured data at all points to obtain the total water depth at the anchor point so as to obtain profile density values from the measurement device at different depths underwater, and drawing and generating a curve.

Description

Underwater profile density measurement system and method Technical Field

[0001] The present invention relates to the technical field of ocean hydrological monitoring, and in particular to an underwater profile density measurement system and method. Background Art

[0002] The complex marine environment at river estuaries and offshore areas makes the properties of seawater uncertain. During offshore engineering construction, seawater density has a significant impact. Construction disturbs the water, triggering the rise of bottom silt and increasing the content of soluble salts and suspended particles in the water. This causes a sharp increase in the rate of change of buoyancy within the construction area, posing a serious safety hazard to underwater structures and divers. The traditional approach is to obtain water samples at different depths and send them to the laboratory to measure the relationship between the volume and mass of the sampled liquid. This method is inefficient, and after long periods of stagnation, suspended matter settles, reducing the density and mismatching the actual density distribution. This results in large errors and is not conducive to direct guidance of on-site construction. In addition, inland river and offshore areas are affected by tidal factors, and equipment and methods that rely on direct calculation of density at a known water depth are prone to distortion. Furthermore, the flow rate in the marine environment varies greatly, and methods such as vertical cables cannot maintain a vertical state in practice. The deeper the water, the greater the error, making it increasingly difficult to accurately measure the depth and density of different water layers.

[0003] In such waters, including rivers and offshore construction areas, vertical cable monitors used to monitor water density often struggle to maintain their cables in a vertical position underwater due to currents. This results in significant errors in the measured depth density due to cable bending when measuring profiles at different depths. For example, patent CN114604364A discloses a tethered underwater helicopter profile measurement system and method, which includes a shore station system and an underwater profile measurement system communicating with it. The underwater profile measurement system includes a floating ball, an underwater helicopter, a channel cable, an upper charging damping block, a lower damping block, and an anchoring system. The cable is controlled by the underwater helicopter to maintain its vertical orientation. However, this method relies on the damping block for power supply and cannot guarantee that the cable remains absolutely vertical as the depth increases. This inevitably leads to significant errors in measurement accuracy. Furthermore, the entire system is expensive, making it unsuitable for offshore engineering applications.

[0004] Summary of the Invention

[0005] In order to solve the problems in the above-mentioned background technology, the present application provides an underwater profile density measurement system and method, which can instantly obtain the density of different underwater profiles without the need for laboratory testing, and is not restricted by whether the cable remains in a vertical state. It does not need to consider the rise and fall of the water level caused by tidal phenomena, and does not need to measure the value of a fixed depth. Instead, it obtains accurate seawater depth values ​​through an integral digital method. It is suitable for the field of hydrological monitoring of underwater engineering construction in oceans and inland rivers. It has a simple structure and low cost, and is suitable for engineering promotion and use.

[0006] To achieve the above objectives, the technical solutions provided by this application are as follows:

[0007] An underwater profile density measurement system, comprising a measuring vessel, an anchor, a steel wire rope, a wire guide, a parameter measuring device, a measurement and control transmission rope, and a data analysis system; wherein

[0008] The anchor is connected to the steel wire rope to anchor the survey ship underwater;

[0009] The parameter measuring device is fixedly arranged at the end of the measurement and control transmission rope and is movably connected to the wire rope through the wire walker, so that the parameter measuring device moves from bottom to top along the wire rope with equal spacing and the same curvature;

[0010] The measurement and control transmission rope is data-connected to the parameter measurement device and the data analysis system, and there are continuous marking points at equal intervals on the measurement and control transmission rope, and the spacing is equal to the length of the parameter measurement device;

[0011] At least two water pressure gauges are fixedly arranged in the parameter measuring device, the distance between the water pressure gauges is fixed and an inclinometer is arranged in the middle for measuring the angle change of the parameter measuring device in real time;

[0012] When the parameter measuring device moves along the steel wire rope, at least two water pressure values ​​measured in real time and the measured water pressure value are transmitted to the data analysis system, the real-time average density of the water body at the location of the parameter measuring device is calculated, and the corresponding water depth is obtained by integrating the parameter measuring device after it is pulled out of the water surface, and a corresponding relationship curve between the water body profile density and the water depth is drawn.

[0013] Compared with the existing technology, the present application measures the water pressure value and inclination angle of the section where the parameter measuring device is located in real time during the process of the parameter measuring device moving from bottom to top along the wire rope, and converts it into the water density of different underwater sections through calculation of the data analysis system; finally, the true water depth of all sampling points is determined by depth integration to obtain the section water depth and corresponding density value. The solution can instantly obtain the density value of different underwater sections without the need for sampling and testing in the laboratory, regardless of whether the cable remains vertical, and without considering tidal phenomena such as rising water levels.

[0014] Preferably, the measurement and control transmission rope is composed of an acquisition control line, a data transmission line, and a flexible nylon rope, and the surfaces of the acquisition control line and the data transmission line are respectively coated with anti-interference aluminum foil, and the measurement and control transmission rope is provided with equally spaced marks.

[0015] Specifically, the inclinometer may be a mechanical compass, a laser compass, or a fiber optic compass for real-time attitude angle measurement.

[0016] Specifically, the water pressure gauge and the inclinometer are arranged in a straight line in the parameter measuring device.

[0017] A method for measuring underwater profile density comprises the following steps:

[0018] S1: When the survey vessel arrives at the designated measurement location, the anchor-connected wire rope is lowered into the water to anchor the vessel, keeping it fixed.

[0019] S2: The steel wire rope forms a curve underwater, and the parameter measurement device enters the water bottom along the measurement and control transmission rope and maintains a flexible connection with the steel wire rope;

[0020] S3: There are evenly spaced continuous marking points on the measurement and control transmission rope. The measurement and control transmission rope is pulled one by one at the evenly spaced and continuous marking points to move the parameter measuring device from bottom to top along the rope. Two water pressure values ​​of the parameter measuring device underwater at different cross-sectional positions and the tilt angle of the device during measurement are collected;

[0021] S4: After the parameter measuring device is pulled out of the water one by one, the water depth at the anchoring location is calculated by integration, thereby obtaining the water depth at which the parameter measuring device is located when collecting data each time;

[0022] S5: The collected water pressure values ​​and tilt angle data of the same group are transmitted to the data analysis system, and the average density of the water body at each collection record is calculated respectively; the average density of the water body is corresponded to the depth of the collection point obtained by the integral calculation, and a relationship curve between the underwater profile density and the depth is drawn.

[0023] Preferably, in step S3, the parameter measuring device collects water pressure values ​​and tilt angles at different depths of water by:

[0024] S301: collecting water pressure values ​​of two water pressure gauges and tilt angles of inclinometers located at different depths when the parameter measuring device sinks to a specified depth;

[0025] S302: Lift the measurement and control transmission rope according to the mark, drive the parameter measurement device to slide up along the wire rope, and collect the water pressure value and tilt angle of the same group after each lift;

[0026] S303: After the parameter measuring device is lifted to the measuring top, it is lowered again one by one according to the mark, and the water pressure value and tilt angle of the same group after each lowering are collected;

[0027] S304: Grouping data collected at the same water depth for data processing to reduce errors when the wire rope curve changes significantly due to drifting.

[0028] Specifically, the step of determining the water depth at each collection in step S4 is as follows:

[0029] S401: After the parameter measurement device is brought out of the water, the water depth at the time of initial anchoring is obtained by integrating the collected data over multiple times;

[0030] S402: The water depth of the device at each collection is calculated by calculating the water depth of the initial state. Further, the calculation steps of different depths and average density of water bodies in S5 are as follows:

[0031] S501: The position during acquisition is recorded as Y i , record the water pressure value P of the upper water pressure gauge at this time i1 , lower water pressure value P i2 , the inclination angle is α i , the depth H of the upper water pressure gauge from the water surface i1 , the depth H of the lower water pressure gauge from the water surface i2 , L is the distance between the two water pressure gauges; then: ΔY i =H i2 -H i1 =L / tan(α i ) (4);

[0032] S502: The anchor head is taken as the reference point O, and the coordinates are recorded as (X0, Y0). The depth of each measuring point of the wire rope is determined as:

[0033] in,

[0034] L—the distance between two water pressure gauges;

[0035] i—measurement point number, i=1, 2, ..., j;

[0036] S503: Calculate and determine Y i ~Y i +ΔY i The corresponding average density within the range is

[0037] Continue to pull the measurement and control transmission rope ΔY to the fixed distance mark point Y i+1 When the upper water pressure value P is recorded again i+1,1 , lower water pressure value P i+1,2 , tilt angle α i+1 , Y i+1 ~Y i+1 +ΔY i The corresponding average density within the range is And so on;

[0038] The water depth H of the water area to be measured can be determined by calculation:

[0039] The depth of a certain acquisition measurement point is:

[0040] S504: To eliminate the error caused by drift of the parameter measurement device, calculate ρ for the water pressure value and tilt angle value data measured during the lifting and lowering process. wi ,Right now

[0041] Specifically, the data analysis system is a MATLAB data system.

[0042] The beneficial effects of the present invention are:

[0043] 1. The measurement system of the present invention has a simple composition, and the components involved are all common and easily purchased accessories. The assembly operation is easy, easy to use, and has high accuracy. It is suitable for hydrological monitoring required for inland rivers and offshore underwater projects, especially for measuring underwater profile density.

[0044] 2. The measurement method of the present invention involves pulling the measurement and control transmission rope at consecutive, evenly spaced marks, driving the parameter measurement device along the wire rope from the bottom up at the connection point between the anchor and the wire rope, collecting the water pressure and tilt angle of the parameter measurement device underwater at different cross-sectional locations. The average density of the water around the parameter measurement device at the time of collection is determined using the built-in algorithm of the data analysis system.

[0045] 3. At the same time, using the concept of integration, by integrating the multiple data collected by the device from the anchor point to the water surface, the water depth H in the initial state is obtained, and then the accurate water depth H at each collection time is obtained. t , and finally obtain the one-to-one correspondence between density and water depth and draw the profile density curve;

[0046] 4. A set of data is formed by two positive and negative tests, and the two calculation results at the same depth are compared to eliminate the errors in angle and pressure values. This calculation scheme has high calculation accuracy and strong reliability, and the algorithm is clear and concise. It meets the requirements of real-time, accurate and convenient hydrological monitoring of underwater engineering projects, and is particularly suitable for measuring underwater profile density.

[0047] 5. Compared with traditional measurement methods, the measurement system of the present invention is smaller in size and its components are low-cost. It does not rely on the known water depth of the measuring device and does not require the measuring line to remain vertical underwater. The tidal effect of the rising and falling water surface can be ignored. It is easy to operate, has a clear principle, and an ingenious calculation method. It provides a new measurement idea for the field of underwater engineering hydrological monitoring, especially for the rapid measurement of underwater profile density. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG1 is a schematic diagram of the overall structure of a measurement system in an embodiment of the present invention;

[0049] FIG2 is a partial enlarged view of portion A in FIG1 according to an embodiment of the present invention;

[0050] FIG3 is a schematic diagram of calculation of an underwater profile in an embodiment of the present invention;

[0051] FIG4 is a diagram showing the steps of a measurement method according to an embodiment of the present invention;

[0052] FIG5 is a graph showing an underwater cross-section of an offshore water area in a bay area according to an embodiment of the present invention;

[0053] FIG6 is a graph showing an underwater cross-section of a device lowered into offshore waters of a bay area according to an embodiment of the present invention;

[0054] FIG7 is a diagram of an underwater cross-section of an inland river estuary according to an embodiment of the present invention;

[0055] FIG8 is a curve diagram of an underwater cross section of an inland river estuary according to an embodiment of the present invention;

[0056] In the figure, marks 1-measurement ship, 2-anchor, 3-wire rope, 4-measurement and control transmission rope, 5-parameter measurement device, 6-marker, 7-angle meter, 8-water pressure gauge, and 10-wire guide. DETAILED DESCRIPTION

[0057] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. The components of the present invention generally described and shown in the drawings herein can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present invention.

[0058] Example

[0059] In order to solve the problem of real-time measurement of underwater profile density in hydrological engineering projects where rivers flow into estuaries, bay areas, and even offshore waters, and to be suitable for the use and promotion of hydrological engineering projects, please refer to Figures 1 and 2. The present invention proposes an underwater profile density measurement system and method, which includes a measurement vessel 1, an anchor 2, a wire rope 3, a wire routing device 10, a parameter measurement device 5, a measurement and control transmission rope 4, and a data analysis system;

[0060] The anchor 2 is connected to the end of the wire rope 3. When the measuring vessel 1 reaches the designated measuring position, the anchor 2 is dropped into the water for anchoring and fixing, thereby anchoring the measuring vessel underwater. An additional anchor 2 for anchoring and fixing can also be added for use in testing waters with large currents or wind speeds.

[0061] The parameter measuring device 5 is fixedly arranged at the end of the measurement and control transmission rope 4 and is movably connected to the wire rope 3 through the wire walker 10, so that the parameter measuring device 5 can be displaced from bottom to top along the wire rope 3 with equal spacing and the same curvature, so as to achieve the goal that when the parameter measuring device 5 performs sliding measurement on the wire rope 3, the tested inclination angle value is the same as the curvature of the wire rope 3 underwater, thereby reducing measurement errors; two water pressure gauges 8 are fixedly arranged in the parameter measuring device 5, and the spacing between the water pressure gauges 8 is fixed and an inclinometer 7 is provided for real-time measurement of the angle change of the parameter measuring device 5, wherein the water pressure gauge 8 and the inclinometer 7 are arranged in a straight line in the parameter measuring device, so that the water pressure gauge 8 and the inclinometer 7 can maintain the consistency of the inclination angle when measuring the same set of data, which is convenient for subsequent data processing and calculation. The inclinometer 7 used in this embodiment is a high-precision compass, and one of a mechanical compass, a laser compass, and a fiber optic compass can also be selected according to the use environment;

[0062] The measurement and control transmission rope 4 is data-connected to the parameter measuring device 5 and the data analysis system. The measurement and control transmission rope 4 is composed of an acquisition control line, a data transmission line, and a flexible nylon rope. The surfaces of the acquisition control line and the data transmission line are respectively coated with tin foil. Equally spaced and continuous marks 6 are set on the measurement and control transmission rope 4. The two water pressure values ​​and inclination angle values ​​collected in the same group are transmitted to the data analysis system for analysis and calculation through the data transmission line. The coated tin foil can reduce data interference between the water pressure gauge 8 and the inclinometer 7 when transmitting data. The mark 6 is used to control the parameter measuring device 5 to slide along the wire rope 3 at equal intervals each time it is lifted, which facilitates data fitting.

[0063] When the parameter measuring device 5 moves up and down along the steel wire rope 3, the real-time measured water pressure value and angle value are transmitted to the data analysis system, and the collected data are stored in the data analysis system. The data analysis system has a built-in algorithm, which can obtain the average density of the water body in the collection layer through the collected data; after the parameter measuring device is pulled from the anchor point to the water outlet one by one, the water depth at the anchor point can be obtained by integration based on the stored data, and then the water depth at which the parameter measuring device is located each time data is collected can be obtained, and then the profile density relationship at different water depths can be obtained through the stored density data; according to the corresponding relationship, the profile density curve is drawn to fit the real-time underwater profile density curve. The data analysis system used in the present invention is a MATLAB data system.

[0064] Referring to FIG4 , the measurement system of the present invention processes the measured data in the following steps:

[0065] S1: When the survey vessel arrives at the designated measurement location, the anchor-connected wire rope is lowered into the water to anchor the vessel, keeping it fixed.

[0066] S2: The steel wire rope forms a curve underwater, and the parameter measurement device enters the water bottom along the measurement and control transmission rope and maintains a flexible connection with the steel wire rope;

[0067] S3: There are evenly spaced marking points on the measurement and control transmission rope. The measurement and control transmission rope is pulled one by one according to the evenly spaced marking points, so that the parameter measuring device moves from bottom to top along the wire rope. Two water pressure values ​​of the parameter measuring device underwater at different cross-sectional positions and the tilt angle of the device during measurement are collected;

[0068] S4: After the parameter measuring device is pulled out of the water one by one, the water depth at the anchoring location is calculated by integration, thereby obtaining the water depth at which the parameter measuring device is located when collecting data each time;

[0069] S5: The collected water pressure values ​​and tilt angle data of the same group are transmitted to the data analysis system, and the average density of the water body at each collection and recording is calculated respectively; and a curve corresponding to the underwater profile density and depth is drawn corresponding to the calculated average density of the water body.

[0070] The steps of the parameter measuring device 5 in step S3 for collecting water pressure values ​​and tilt angle values ​​at different depths are as follows:

[0071] S301: collecting water pressure values ​​of two water pressure gauges 8 and the tilt angle of the inclinometer 7 at different depths when the parameter measuring device 5 sinks to a specified depth;

[0072] S302: Lift the measurement and control transmission rope 4 according to mark 6, driving the parameter measurement device 5 to slide and rise along the wire rope 3, and collect the water pressure value and tilt angle of the same group after each lift;

[0073] S303: After the parameter measuring device 5 is lifted to the measuring top, it is lowered again one by one according to the mark 6, and the water pressure value and tilt angle of the same group after each lowering are collected;

[0074] S304: The data collected at the same water depth are grouped together for data processing to reduce errors when the curve of the wire rope 3 changes significantly due to drifting.

[0075] The steps for determining the water depth at each acquisition in step S4 are:

[0076] S401: After the parameter measurement device is brought out of the water, the water depth at the time of initial anchoring is obtained by integrating the collected data over multiple times;

[0077] S402: The water depth of the device at each collection is obtained by calculating the water depth in the initial state.

[0078] Further:

[0079] The density of the surrounding water body is calculated based on the formula from the collected data;

[0080] After the parameter measurement device is brought out of the water, the initial water depth H is obtained based on the integration of multiple collected data;

[0081] The water depth Hi where the device is located at each time of collection is obtained by back-calculating H;

[0082] According to the previously calculated surrounding water density and Hi at the time of collection, a one-to-one correspondence is formed and made into a table;

[0083] Draw density curves at different depths of the profile based on a one-to-one correspondence.

[0084] Please refer to FIG3 , where the calculation steps for different depths and average water density in S5 are as follows:

[0085] S501: The position during acquisition is recorded as Y i , record the water pressure value P of the upper water pressure gauge at this time i1 , lower water pressure value P i2 , the inclination angle is α i , the depth H of the upper water pressure gauge from the water surface i1 , the depth H of the lower water pressure gauge from the water surface i2 , L is the distance between the two water pressure gauges; then: ΔY i =H i2 -H i1 =L / tan(α i ) (4);

[0086] S502: The anchor head is taken as the reference point O, and the coordinates are recorded as (X0, Y0). The depth of each measuring point of the wire rope is determined as:

[0087] in,

[0088] L—the distance between two water pressure gauges;

[0089] i—measurement point number, i=1, 2, ..., j;

[0090] S503: Calculate and determine Y i ~Y i +ΔY i The corresponding average density within the range is

[0091] Continue to pull the measurement and control transmission rope ΔY to the fixed distance mark point Y i+1 When the upper water pressure value P is recorded again i+1,1 , lower water pressure value P i+1,2 , tilt angle α i+1 , Y i+1 ~Y i+1 +ΔY i The corresponding average density within the range is And so on;

[0092] The water depth H of the water area to be measured can be determined by calculation:

[0093] The depth of a certain acquisition measurement point is:

[0094] S504: To eliminate the error caused by drift of the parameter measurement device, calculate ρ for the water pressure value and tilt angle value data measured during the lifting and lowering process. wi ,Right now

[0095] Please refer to Figures 5-8. In this embodiment, two groups of water environments are adopted to collect water pressure values ​​and inclination angles at different water depths according to the processes of lowering and lifting. Calculations are performed according to the above-mentioned parameter data processing process, and finally a water density-corresponding depth relationship curve is fitted. Figures 5-6 are underwater profile measurement curves of the nearshore waters of the bay area, and Figures 7-8 are underwater profile measurement curves of the waters at the estuary of an inland river.

[0096] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it should be understood that although this specification is described in terms of implementation methods, not each implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity, and those skilled in the art should regard the specification as a whole. The technical solutions in the various embodiments can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A water profile density measurement system, characterized in that The measurement system includes a measurement vessel, an anchor, a steel wire rope, a wire guide, a parameter measurement device, a measurement and control transmission rope, and a data analysis system; in The anchor is connected to the steel wire rope to anchor the survey ship underwater; The parameter measuring device is fixedly arranged at the end of the measurement and control transmission rope and is movably connected to the wire rope through the wire walker, so that the parameter measuring device moves from bottom to top along the wire rope with equal spacing and the same curvature; The measurement and control transmission rope is data-connected with the parameter measurement device and the data analysis system; At least two water pressure gauges are fixedly arranged in the parameter measuring device, the distance between the water pressure gauges is fixed and an inclinometer is arranged in the middle for measuring the angle change of the parameter measuring device in real time; When the parameter measuring device moves along the wire rope, at least two water pressure values ​​and the measured water pressure value measured in real time are transmitted to the data analysis system to calculate the real-time average density of the water body at different measurement positions, and the water depth values ​​corresponding to different measurement positions calculated by integration after the parameter measuring device is pulled out of the water surface are combined to draw a corresponding relationship curve between the water body profile density and the water depth.

2. The measuring system according to claim 1, characterized in that The measurement and control transmission rope consists of an acquisition control line, a data transmission line, and a flexible nylon rope, and the surfaces of the acquisition control line and the data transmission line are respectively covered with anti-interference aluminum foil. Continuous marks with equal intervals are set on the measurement and control transmission rope, and the spacing length is the same as that of the parameter measurement device.

3. The measuring system according to claim 1, characterized in that The inclinometer can be selected from a mechanical compass, a laser compass, and a fiber optic compass for real-time attitude angle measurement.

4. The measuring system according to claim 1, characterized in that The water pressure gauge and the inclinometer are arranged in a straight line in the parameter measuring device.

5. A method for measuring water body profile density, comprising using a measurement system as claimed in any one of claims 1 to 4, characterized in that The method comprises the following steps: S1: When the survey vessel arrives at the designated measurement location, the anchor-connected wire rope is lowered into the water to anchor the vessel, keeping it fixed. S2: The steel wire rope forms a curve underwater, and the parameter measurement device enters the water bottom along the measurement and control transmission rope and maintains a flexible connection with the steel wire rope; S3: There are evenly spaced and continuous marking points on the measurement and control transmission rope. The measurement and control transmission rope is pulled one by one at the evenly spaced and continuous marking points to move the parameter measuring device from bottom to top along the rope. Two water pressure values ​​of the parameter measuring device underwater at different cross-sectional positions and the tilt angle of the device during measurement are collected; S4: After the parameter measuring device is pulled out of the water one by one, the water depth at the anchoring location is calculated by integration, thereby obtaining the water depth at which the parameter measuring device is located when collecting data each time; S5: The collected water pressure values ​​and tilt angle data of the same group are transmitted to the data analysis system, and the average density of the water body at each collection record is calculated respectively; and the depth of the collection position obtained by the integral calculation is used to draw a curve of the relationship between the underwater profile density and the depth.

6. The measuring method according to claim 5, characterized in that In step S3, the parameter measuring device collects the underwater water pressure values ​​and inclination angles at different cross-sectional positions as follows: S301: After the parameter measuring device is sunk to the depth to be measured, the parameters at different depths are collected. The water pressure values ​​of the two water pressure gauges and the tilt angle of the inclinometer; S302: Lifting the measurement and control transmission rope according to the evenly spaced and continuous markings, driving the parameter measurement device to slide up along the wire rope, and collecting the water pressure value and tilt angle of the same group after each lift; S303: After the parameter measuring device is lifted to the measuring top, it is lowered again one by one according to the mark, and the water pressure value and tilt angle of the same group after each lowering are collected; S304: Grouping data collected at the same water depth for data processing to reduce errors when the wire rope curve changes significantly due to drifting.

7. The measuring method according to claim 5, characterized in that The step of determining the water depth at each acquisition in step S4 is as follows: S401: After the parameter measurement device is brought out of the water, the water depth at the time of initial anchoring is obtained by integrating the collected data over multiple times; S402: The water depth of the device at each collection is obtained by calculating the water depth in the initial state.

8. The measuring method according to claim 5, characterized in that The calculation steps of different depths and average water density in S5 are as follows: S501: The position during acquisition is recorded as Y i , record the water pressure value P of the upper water pressure gauge at this time i1 , lower water pressure value P i2 , the inclination angle is α i , the depth H of the upper water pressure gauge from the water surface i1 , the depth H of the lower water pressure gauge from the water surface i2 , L is the distance between the two water pressure gauges; then: <h2 style=";text-align:left;direction:ltr">ΔY<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> =H<h2 style=";text-align:left;direction:ltr"> i2 <h2 style=";text-align:left;direction:ltr"> -H<h2 style=";text-align:left;direction:ltr"> i1 <h2 style=";text-align:left;direction:ltr"> =L / tan(α<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> (4); S502: The anchor head is taken as the reference point O, and the coordinates are recorded as (X0, Y0). The depth of each measuring point of the wire rope is determined as follows: in, L—the distance between two water pressure gauges; i—measurement point number, i=1, 2, ..., j; S503: Calculate and determine Y i ~Y i +ΔY i The corresponding average density within the range is Continue to pull the measurement and control transmission rope ΔY to the fixed distance mark point Y i+1 When the upper water pressure value P is recorded again i+1,1 , lower water pressure value P i+1,2 , tilt angle α i+1 , Y i+1 ~Y i+1 +ΔY i The corresponding average density within the range is And so on; The water depth H of the water area to be measured can be determined by calculation: The depth of a certain acquisition measurement point is: S504: To eliminate the error caused by drift of the parameter measurement device, calculate ρ for the water pressure value and tilt angle value data measured during the lifting and lowering process. wi ,Right now 9. The measuring method according to claim 1, characterized in that The data analysis system is a MATLAB data system.

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