Suspended sediment concentration inversion method capable of resisting particle size interference

Abstract

The invention provides a suspended sediment concentration inversion method capable of resisting particle size interference, which comprises the following steps of: standardizing the original acoustic echo intensity of each observation grid to obtain the standardized volume back scattering intensity; establishing a sonar equation considering the sound wave attenuation of the sediment particles, and performing explicit processing on the sonar equation considering the sound wave attenuation of the sediment particles to obtain an explicit inversion model which resists particle size interference and considers the on-way change of the sediment particle size; and performing model parameter calibration on the explicit inversion model, and performing suspended sediment concentration inversion on the river observation section based on the suspended sediment concentration inversion value of each observation grid. According to the method, the dependence of ADCP inversion of the suspended sediment concentration on suspended sediment particle size distribution is effectively eliminated, and the stability and accuracy of suspended sediment concentration inversion are improved. The particle size interference resistant explicit method can realize continuous and real-time suspended sediment concentration monitoring, and is suitable for various water environments such as rivers, lakes, reservoirs and the like.

Description

Technical Field

[0001] This invention relates to the field of suspended sediment concentration inversion technology, and specifically to a suspended sediment concentration inversion method that is resistant to particle size interference. Background Technology

[0002] Suspended sediment concentration is an important parameter in river dynamics research and water and sediment regulation engineering. Traditional methods for obtaining suspended sediment concentration mainly rely on field sampling and experimental analysis, which cannot achieve long-term, continuous and large-scale monitoring.

[0003] Acoustic Doppler Current Profiler (ADCP) can indirectly invert suspended sediment concentration by measuring the intensity of acoustic backscattering in water, and is therefore widely used in rivers, reservoirs, and nearshore environments. However, the acoustic signal measured by ADCP is affected not only by the suspended sediment concentration but also by the significant interference from the suspended sediment particle size distribution. When the suspended sediment particle size distribution in the water body varies greatly, the inversion method based solely on the empirical relationship between acoustic backscattering intensity and suspended sediment concentration is prone to bias, affecting the accuracy of suspended sediment concentration acquisition.

[0004] Therefore, there is an urgent need for a suspended sediment concentration inversion method that can effectively weaken or eliminate the influence of particle size interference in order to improve the accuracy and applicability of ADCP monitoring. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a suspended sediment concentration inversion method that is resistant to particle size interference, which can effectively solve the above problems.

[0006] The technical solution adopted in this invention is as follows:

[0007] This invention provides a method for retrieving suspended sediment concentration that is resistant to particle size interference, comprising the following steps:

[0008] Step S1: The original acoustic echo intensity of each observation grid of the river observation section is measured using an acoustic Doppler current profiler; several observation grids are selected as reference grids, and the measured value of suspended sediment concentration of each reference grid is obtained.

[0009] Step S2: Standardize the raw acoustic echo intensity of each observation grid to obtain the standardized volume backscatter intensity.

[0010] Step S3: Establish a sonar equation that considers the attenuation of sound waves by sediment particles, and explicitly process the sonar equation that considers the attenuation of sound waves by sediment particles to obtain an explicit inversion model that is resistant to particle size interference and considers the variation of sediment particle size along the path.

[0011] Step S4: Using the measured values ​​of suspended sediment concentration and the relationship between the normalized volume backscattering intensity of each of the reference grids, the explicit inversion model is calibrated to obtain the explicit inversion model after model parameter calibration.

[0012] Step S5: Input the standardized volume backscatter intensity of each observation grid into the explicit inversion model after model parameter calibration to obtain the suspended sediment concentration inversion value of each observation grid, thereby realizing the suspended sediment concentration inversion of the river observation section.

[0013] Furthermore, the raw acoustic echo intensity of each observation grid is normalized to obtain the normalized volumetric backscatter intensity, specifically as follows:

[0014] The original acoustic echo intensity of each observation grid is corrected for distance attenuation, fluid absorption, and noise subtraction to obtain the normalized volumetric backscatter intensity.

[0015] Furthermore, the raw acoustic echo intensity of each observation grid is standardized using formula (1):

[0016] (1)

[0017] in: The normalized volumetric backscattering intensity of the observation grid; The original acoustic echo intensity of the observed grid; This is background noise; The radial distance between the observation grid and the acoustic Doppler current profiler; The transducer temperature used in the acoustic Doppler current profiler; The transmission pulse length of the acoustic Doppler current profiler; The transmission power of the acoustic Doppler current profiler; The instrument gain parameter of the acoustic Doppler current profiler; The spherical expansion parameter in the near field of the transducer; The correction coefficient is used to comprehensively consider the effects of fluid absorption and sediment particles on sound wave attenuation.

[0018] Furthermore, Expressed by formula (2):

[0019] (2)

[0020] in: The fluid absorption coefficient; The attenuation coefficient of sound waves by sediment particles is denoted as ρ.

[0021] Furthermore, the fluid absorption coefficient The expression is:

[0022] (3)

[0023] (4)

[0024] (5)

[0025] in: , and This is an empirical coefficient; The water temperature of the observed grid; The salinity of the water body in the observation grid; The water body of the observation grid value; The ADCP acoustic frequency of the acoustic Doppler current profiler; This represents the relaxation frequency of boric acid. is the relaxation frequency of magnesium sulfate.

[0026] Furthermore, the effect of sediment particles on the sound wave attenuation coefficient The expression is:

[0027] (6)

[0028] in:

[0029] The meaning is: the radial distance from the acoustic Doppler current profiler is The radial distance along the path between the observation grid and the acoustic Doppler current profiler is... The suspended sediment concentration in the intermediate observation grid;

[0030] The radial distance is The scattering attenuation coefficient of suspended sand on sound waves per unit volume within the intermediate observation grid along the route.

[0031] The radial distance is The viscous absorption attenuation coefficient of suspended sand on sound waves per unit volume in the intermediate observation grid along the route.

[0032] The radial distance is The total attenuation coefficient of suspended sand on sound waves per unit volume within the intermediate observation grid along the path. .

[0033] Furthermore, the sonar equation considering the attenuation of sound waves by sediment particles is as follows:

[0034] (7)

[0035] in:

[0036] The meaning is: the radial distance from the acoustic Doppler current profiler is When the observation grid is standardized using formula (1), the attenuation coefficient of the sediment particles on the sound waves is set to... The normalized volume backscatter intensity obtained when it is 0, that is: the normalized volume backscatter intensity obtained without considering the attenuation correction of sound waves by sediment particles.

[0037] The radial distance is The suspended sediment concentration of the observation grid;

[0038] The radial distance is The scattering characteristics of suspended sand in the observation grid.

[0039] Furthermore, the explicit inversion model that resists particle size interference and considers the variation of sediment particle size along the path is as follows:

[0040] (8)

[0041] in:

[0042] The radial distance is The exponential form of the normalized volumetric backscattering intensity obtained by neglecting the correction for acoustic attenuation by sediment particles in the aforementioned observation grid. ;

[0043] The radial distance to be calibrated is The model parameters of the observation grid, ;

[0044] The radial distance is The model parameters to be calibrated for the intermediate observation grid along the process;

[0045] The radial distance is The exponential form of the normalized volumetric backscatter intensity obtained when the intermediate observation grid along the path does not consider the correction of sound wave attenuation by sediment particles.

[0046] Furthermore, it also includes:

[0047] Step S6: Collect water samples periodically at set intervals to obtain the measured values ​​of suspended sediment concentration in the reference grid; based on the measured values ​​of suspended sediment concentration in the reference grid, calibrate the model parameters of the explicit inversion model again, and update the explicit inversion model after model parameter calibration.

[0048] The suspended sediment concentration inversion method resistant to particle size interference provided by this invention has the following advantages:

[0049] 1. It effectively eliminates the dependence of ADCP inversion of suspended sediment concentration on suspended sediment particle size distribution, improving the stability and accuracy of suspended sediment concentration inversion;

[0050] 2. By combining on-site water sample calibration with acoustic theory correction, the explicit method reduces the difficulty and intensity of on-site sampling, and has physical rationality and scalability;

[0051] 3. Explicit methods that resist particle size interference can achieve continuous and real-time monitoring of suspended sediment concentration, and are applicable to various water environments such as rivers, lakes, and reservoirs. Attached Figure Description

[0052] Figure 1 A flowchart of a suspended sediment concentration inversion method that resists particle size interference provided by the present invention;

[0053] Figure 2 This is an empirical relationship diagram between volumetric backscattering intensity and suspended sediment concentration obtained based on traditional methods, which assume that the sediment particle size is uniform over time.

[0054] Figure 3 This is a comparison chart of the inversion results and the measured results of the method proposed in this invention. Detailed Implementation

[0055] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] To overcome the dependence of existing technologies on suspended sediment particle size distribution in acoustic inversion of suspended sediment concentration, this invention provides a suspended sediment concentration inversion method that is resistant to particle size interference. It can establish an explicit inversion model by combining on-site measured water sample calibration and ADCP original acoustic echo intensity, effectively reducing the impact of suspended sediment particle size distribution characteristics on the accuracy of suspended sediment concentration inversion.

[0057] This invention provides a method for retrieving suspended sediment concentration that is resistant to particle size interference, comprising the following steps:

[0058] Step S1: The original acoustic echo intensity of each observation grid of the river observation section is measured using an acoustic Doppler current profiler; several observation grids are selected as reference grids, and the measured value of suspended sediment concentration of each reference grid is obtained.

[0059] In this invention, the river observation section is gridded to generate several observation grids. The number of reference grids selected is not limited, nor is the location of the selected reference grids within the river observation section; adjustments are made based on actual needs.

[0060] This invention does not limit the measurement method using an acoustic Doppler current profiler or the method for obtaining the measured values ​​of suspended sediment concentration. As one implementation method, the following approach can be used:

[0061] Sampling points were set up at the ADCP measurement section, and water samples were collected simultaneously. The collected water samples were analyzed in the laboratory to obtain the actual measured values ​​of suspended sediment concentration and particle size distribution characteristics.

[0062] Furthermore, on-site sampling requires at least two sampling points in the vertical direction, with the preferred sampling locations being one water sample from the surface and one near the riverbed; a further preferred option is to simultaneously deploy a turbidity meter or a single-point sediment characteristic measuring instrument such as LISST and ADCP for simultaneous sampling, and match the original acoustic echo intensity of ADCP with the measured value of suspended sediment concentration based on the instrument time and sampling depth.

[0063] Step S2: Standardize the raw acoustic echo intensity of each observation grid to obtain the standardized volume backscatter intensity.

[0064] Specifically, based on the acoustic wave scattering and attenuation characteristics of ADCP, a series of correction methods are used to preprocess the original acoustic echo intensity to achieve standardization.

[0065] For example, the raw acoustic echo intensity of each observation grid is corrected for distance attenuation, fluid absorption, and noise subtraction to obtain the normalized volumetric backscatter intensity. Among them, distance attenuation correction is used to compensate for the geometric diffusion loss of sound waves during propagation in water; absorption correction considers the absorption loss of sound wave energy by water and sediment particles; and noise subtraction removes instrument background noise and environmental interference signals.

[0066] Furthermore, the raw acoustic echo intensity of each observation grid is standardized using formula (1):

[0067] (1)

[0068] in: The normalized volumetric backscattering intensity of the observation grid, in dB; The original acoustic echo intensity of the observed grid; This is background noise; The radial distance, in meters, is the distance between the observation grid and the acoustic Doppler current profiler. The transducer temperature used in the acoustic Doppler current profiler is ℃; The transmission pulse length of the acoustic Doppler current profiler is given in meters (m). The transmission power of the acoustic Doppler current profiler is expressed in W. The instrument gain parameter of the acoustic Doppler current profiler; The spherical expansion parameter in the near field of the transducer; The correction factor, dB / m, is used to comprehensively consider the effects of fluid absorption and sediment particles on sound wave attenuation. Expressed by formula (2):

[0069] (2)

[0070] in: The fluid absorption coefficient; The attenuation coefficient of sound waves by sediment particles is denoted as ρ.

[0071] Fluid absorption coefficient The expression is:

[0072] (3)

[0073] (4)

[0074] (5)

[0075] in: , and These are empirical coefficients, for example, 0.106, 0.52, and... ; The water temperature of the observed grid; The salinity of the water body in the observation grid; The water body of the observation grid value; The ADCP acoustic frequency of the acoustic Doppler current profiler; This represents the relaxation frequency of boric acid. is the relaxation frequency of magnesium sulfate.

[0076] The effect of sediment particles on sound wave attenuation coefficient The expression is:

[0077] (6)

[0078] in:

[0079] The meaning is: the radial distance from the acoustic Doppler current profiler is The radial distance along the path between the observation grid and the acoustic Doppler current profiler is... The suspended sediment concentration in the intermediate observation grid;

[0080] The radial distance is The scattering attenuation coefficient of suspended sand on sound waves per unit volume within the intermediate observation grid along the route.

[0081] The radial distance is The viscous absorption attenuation coefficient of suspended sand on sound waves per unit volume in the intermediate observation grid along the route.

[0082] The radial distance is The total attenuation coefficient of suspended sand on sound waves per unit volume within the intermediate observation grid along the path. .

[0083] Step S3: Establish a sonar equation that considers the attenuation of sound waves by sediment particles, and explicitly process the sonar equation that considers the attenuation of sound waves by sediment particles to obtain an explicit inversion model that is resistant to particle size interference and considers the variation of sediment particle size along the path.

[0084] In this invention, the sonar equation considering the attenuation of sound waves by sediment particles is:

[0085] (7)

[0086] in:

[0087] The meaning is: the radial distance from the acoustic Doppler current profiler is When the observation grid is standardized using formula (1), the attenuation coefficient of the sediment particles on the sound waves is set to... The normalized volume backscatter intensity obtained when it is 0, that is: the normalized volume backscatter intensity obtained without considering the attenuation correction of sound waves by sediment particles.

[0088] The radial distance is The suspended sediment concentration of the observation grid;

[0089] The radial distance is The scattering characteristics of suspended sand in the observation grid.

[0090] The explicit inversion model that resists particle size interference and considers the variation of sediment particle size along the path is as follows:

[0091] (8)

[0092] in:

[0093] The radial distance is The exponential form of the normalized volumetric backscattering intensity obtained by neglecting the correction for acoustic attenuation by sediment particles in the aforementioned observation grid. ;

[0094] The radial distance to be calibrated is The model parameters of the observation grid are attenuation correction model parameters related to sediment particle size, taking into account the variation of sediment particle size along the path. ;

[0095] The radial distance is The model parameters to be calibrated for the intermediate observation grid along the process;

[0096] The radial distance is The exponential form of the normalized volumetric backscatter intensity obtained when the intermediate observation grid along the path does not consider the correction of sound wave attenuation by sediment particles.

[0097] The explicit inversion model shown in Formula 8 established in this invention has 0 to... The integral term of the term therefore takes into account the effect of uneven particle size variation along the path.

[0098] Step S4: Using the measured values ​​of suspended sediment concentration and the relationship between the normalized volume backscattering intensity of each of the reference grids, the explicit inversion model is calibrated to obtain the explicit inversion model after model parameter calibration.

[0099] The explicit inversion model established by this invention after parameter calibration is an explicit inversion model resistant to particle size interference: considering the variation of the scattering characteristics of suspended sand particles in the fluid to sound waves along the path, the sonar equation is re-derived, and the relationship between the particle size correction term, the measured value of suspended sand concentration of the reference grid, and the standardized volume backscattering intensity is introduced to establish an explicit inversion model that homogenizes the particle size distribution of sediment along the path.

[0100] Step S5, Suspended sediment concentration inversion:

[0101] The standardized volumetric backscattering intensity of each observation grid is input into the explicit inversion model after model parameter calibration to obtain the suspended sediment concentration inversion value of each observation grid, thereby realizing the suspended sediment concentration inversion of the river observation section.

[0102] Therefore, by calculating the suspended sediment concentration profile on a grid-by-grid basis, the spatial distribution can be obtained, and the result can reflect the changes in suspended sediment concentration at different water depths and lateral locations.

[0103] Step S6, Dynamic Update:

[0104] Water samples are collected periodically at set intervals to obtain the measured values ​​of suspended sediment concentration in the reference grid. Based on the measured values ​​of suspended sediment concentration in the reference grid, the explicit inversion model is calibrated again, and the explicit inversion model is updated after the model parameters are calibrated.

[0105] Specifically, in long-term monitoring, in order to cope with seasonal or sudden changes in water and sediment conditions, water samples are collected periodically or during special periods such as floods to update the model parameters of the explicit inversion model, thereby maintaining the accuracy and stability of the suspended sediment concentration inversion results.

[0106] The following is a specific example:

[0107] The suspended sediment concentration inversion method resistant to particle size interference described in this invention includes the following steps:

[0108] Step 1: Select a suitable ADCP model for on-site observation in the measured river section. The observation equipment used is a Nortek Signature 1000 Acoustic Doppler Current Profiler (ADCP), which is downward-facing and has four lateral beams at a 25° angle to the vertical and one vertical beam. All beams operate at a frequency of 1000 kHz.

[0109] Step 2: During on-site deployment, the ADCP is fixed within a rigid frame designed on the survey vessel. During sampling, the survey vessel is anchored in a pre-set position to maintain stability, and the water sampler and turbidity meter are also fixed within a designed sampling frame to ensure spatial consistency between the water sampler, turbidity meter, and ADCP measurement.

[0110] Step 3: While sampling, the original acoustic echo intensity obtained by the ADCP beam is averaged for 2 minutes to remove interference signals from non-mud and sand targets for subsequent calibration.

[0111] Step 4: The collected water samples were brought back to the laboratory for suspended sediment concentration and particle size analysis. Particle size distribution was measured using a Mastersizer-3000 laser particle size analyzer. During the analysis, the stirring speed was set to 1400 rpm, supplemented with a chemical dispersant and ultrasonic vibration to ensure sufficient particle dispersion and obtain the true suspended sediment particle size distribution. Suspended sediment mass concentration was determined using the membrane filtration method (0.45 μm pore size filter membrane). The obtained suspended sediment concentration and particle size distribution data were used to calibrate the explicit inversion model.

[0112] Step 5: Based on the original acoustic echo intensity recorded by ADCP, the normalized volume backscatter intensity is obtained using formula (1).

[0113] Step 6: Using the relationship between the standardized volume backscatter intensity of the collected water samples and the measured values ​​of suspended sediment concentration, the explicit inversion model is calibrated to obtain the explicit inversion model after model parameter calibration.

[0114] Step 7: Input the standardized volume backscatter intensity obtained based on ADCP into the explicit inversion model after parameter calibration to obtain the suspended sediment concentration inversion value of each grid, thereby realizing the suspended sediment concentration inversion of the river observation section.

[0115] like Figure 2 The figure shows an empirical relationship between volumetric backscattering intensity and suspended sediment concentration, obtained based on the traditional method, which assumes uniform sediment particle size over time. Figure 2 It can be seen that traditional methods are difficult to establish an empirical relationship between suspended sediment concentration and backscattering intensity under non-uniform particle size interference.

[0116] The suspended sediment concentration was inverted using the method of this invention, and the results are as follows: Figure 3 As shown. Figure 3 The left figure shows the relationship between normalized volumetric backscattering intensity and water depth, obtained after normalizing the original acoustic echo intensity measured by ADCP. This yields a normalized volumetric backscattering intensity profile distributed along the water depth direction. Based on this normalized volumetric backscattering intensity profile, the suspended sediment concentration profile retrieved by this invention is compared with the measured results. Figure 3 As shown in the right figure, the suspended sediment concentration profile retrieved by this invention is in good agreement with the measured results. Therefore, it is proven that the suspended sediment concentration retrieval method based on ADCP that is resistant to particle size interference meets the actual needs and has high feasibility. It can provide a new approach for the measurement of suspended sediment concentration.

[0117] This invention provides a method for retrieving suspended sediment concentration that is resistant to particle size interference, and has the following advantages:

[0118] 1. It effectively eliminates the dependence of ADCP inversion of suspended sediment concentration on suspended sediment particle size distribution, improving the stability and accuracy of suspended sediment concentration inversion;

[0119] 2. By combining on-site water sample calibration with acoustic theory correction, the explicit method reduces the difficulty and intensity of on-site sampling, and has physical rationality and scalability;

[0120] 3. Explicit methods that resist particle size interference can achieve continuous and real-time monitoring of suspended sediment concentration, and are applicable to various water environments such as rivers, lakes, and reservoirs.

[0121] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for inverting suspended sediment concentration that is resistant to particle size interference, characterized in that, Includes the following steps: Step S1: The original acoustic echo intensity of each observation grid of the river observation section is measured using an acoustic Doppler current profiler; several observation grids are selected as reference grids, and the measured value of suspended sediment concentration of each reference grid is obtained. Step S2: Standardize the raw acoustic echo intensity of each observation grid to obtain the standardized volume backscatter intensity. Step S3: Establish a sonar equation that considers the attenuation of sound waves by sediment particles, and explicitly process the sonar equation that considers the attenuation of sound waves by sediment particles to obtain an explicit inversion model that is resistant to particle size interference and considers the variation of sediment particle size along the path. Step S4: Using the measured values ​​of suspended sediment concentration and the relationship between the normalized volume backscattering intensity of each of the reference grids, the explicit inversion model is calibrated to obtain the explicit inversion model after model parameter calibration. Step S5: Input the standardized volume backscatter intensity of each observation grid into the explicit inversion model after model parameter calibration to obtain the suspended sediment concentration inversion value of each observation grid, thereby realizing the suspended sediment concentration inversion of the river observation section.

2. The suspended sediment concentration inversion method resistant to particle size interference according to claim 1, characterized in that, The raw acoustic echo intensity of each observation grid is normalized to obtain the normalized volumetric backscatter intensity, specifically as follows: The original acoustic echo intensity of each observation grid is corrected for distance attenuation, fluid absorption, and noise subtraction to obtain the normalized volumetric backscatter intensity.

3. The suspended sediment concentration inversion method resistant to particle size interference according to claim 1, characterized in that, The raw acoustic echo intensity of each observation grid is standardized using formula (1): （1） in: The normalized volumetric backscattering intensity of the observation grid; The original acoustic echo intensity of the observed grid; This is background noise; The radial distance between the observation grid and the acoustic Doppler current profiler; The transducer temperature used in the acoustic Doppler current profiler; The transmission pulse length of the acoustic Doppler current profiler; The transmission power of the acoustic Doppler current profiler; The instrument gain parameter of the acoustic Doppler current profiler; The spherical expansion parameter in the near field of the transducer; The correction coefficient is used to comprehensively consider the effects of fluid absorption and sediment particles on sound wave attenuation.

4. The suspended sediment concentration inversion method resistant to particle size interference according to claim 3, characterized in that, Expressed by formula (2): （2） in: The fluid absorption coefficient; The attenuation coefficient of sound waves by sediment particles is denoted as ρ.

5. The suspended sediment concentration inversion method resistant to particle size interference according to claim 4, characterized in that, Fluid absorption coefficient The expression is: （3） （4） （5） in: , and This is an empirical coefficient; The water temperature of the observed grid; The salinity of the water body in the observation grid; The water body of the observation grid value; The ADCP acoustic frequency of the acoustic Doppler current profiler; This represents the relaxation frequency of boric acid. is the relaxation frequency of magnesium sulfate.

6. The suspended sediment concentration inversion method resistant to particle size interference according to claim 5, characterized in that, The effect of sediment particles on sound wave attenuation coefficient The expression is: （6） in: The meaning is: the radial distance from the acoustic Doppler current profiler is The radial distance along the path between the observation grid and the acoustic Doppler current profiler is... The suspended sediment concentration in the intermediate observation grid; The radial distance is The scattering attenuation coefficient of suspended sand on sound waves per unit volume within the intermediate observation grid along the route. The radial distance is The viscous absorption attenuation coefficient of suspended sand on sound waves per unit volume in the intermediate observation grid along the route. The radial distance is The total attenuation coefficient of suspended sand on sound waves per unit volume within the intermediate observation grid along the path. .

7. The suspended sediment concentration inversion method resistant to particle size interference according to claim 6, characterized in that, The sonar equation considering the attenuation of sound waves by sediment particles is as follows: （7） in: The meaning is: the radial distance from the acoustic Doppler current profiler is When the observation grid is standardized using formula (1), the attenuation coefficient of the sediment particles on the sound waves is set to... The normalized volume backscatter intensity obtained when it is 0, that is: the normalized volume backscatter intensity obtained without considering the attenuation correction of sound waves by sediment particles. The radial distance is The suspended sediment concentration of the observation grid; The radial distance is The scattering characteristics of suspended sand in the observation grid.

8. The suspended sediment concentration inversion method resistant to particle size interference according to claim 7, characterized in that, The explicit inversion model that resists particle size interference and considers the variation of sediment particle size along the path is as follows: （8） in: The radial distance is The exponential form of the normalized volumetric backscattering intensity obtained by neglecting the correction for acoustic attenuation by sediment particles in the aforementioned observation grid. ; The radial distance to be calibrated is The model parameters of the observation grid, ; The radial distance is The model parameters to be calibrated for the intermediate observation grid along the process; The radial distance is The exponential form of the normalized volumetric backscatter intensity obtained when the intermediate observation grid along the path does not consider the correction of sound wave attenuation by sediment particles.

9. The suspended sediment concentration inversion method resistant to particle size interference according to claim 1, characterized in that, Also includes: Step S6: Collect water samples periodically at set intervals to obtain the measured value of suspended sediment concentration of the reference grid; Based on the measured suspended sediment concentration values ​​of the reference grid, the explicit inversion model is calibrated again, and the explicit inversion model after parameter calibration is updated.

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