Method for calculating cross-section sediment flux

Abstract

This invention discloses a method for calculating cross-sectional sediment flux, comprising: acquiring topographic, flow, sediment, and environmental parameters of the target cross-section; performing parameter spatial interpolation to construct a continuous distribution field of cross-sectional flow velocity and sediment concentration; calculating suspended and bedload transport parameters of the cross-section; and, based on the mass conservation principle, using spatially varying exchange coefficients to perform bidirectional synchronous correction of the suspended and bedload parameters to obtain the corrected parameters and synthesize the total sediment flux output of the cross-section. Based on the technical solution proposed in this application, adaptive calculation of sediment transformation under different aquatic environments can be achieved, effectively improving the accuracy of total sediment flux measurement under complex conditions.

Description

Technical Field

[0001] This invention belongs to the field of river dynamics technology, and more specifically, relates to a method for calculating cross-sectional sediment flux. Background Technology

[0002] Cross-sectional sediment flux is a crucial indicator characterizing the intensity of sediment transport in water bodies, and its measurement accuracy directly impacts the scientific validity of delta evolution simulations, reservoir sedimentation assessments, and waterway management planning. Achieving high-precision real-time monitoring of total sediment transport across cross-sections under complex hydrodynamic environments provides vital technical support for revealing watershed material transport patterns, ensuring the safe operation of water conservancy projects, and optimizing river regulation design schemes.

[0003] Currently, the calculation of cross-sectional sediment flux mostly employs a block-weighted method combined with empirical formulas, or uses historical monitoring data to establish correlation models for extrapolation. In suspended sediment measurement, existing technologies often use simple linear interpolation when dealing with irregularly topographically irregular cross-sections, making it difficult to accurately reproduce the nonlinear distribution characteristics of sediment concentration and velocity in the vertical and lateral directions. In bedload measurement, existing methods are mostly based on empirical formulas under fixed conditions, lacking adaptability to dynamic changes in hydrological conditions. Furthermore, existing calculation architectures typically treat suspended and bedload as unrelated independent components and simply superimpose them, failing to fully consider the dynamic transformation relationship between the two components near the bed surface. This results in an insufficiently rigorous description of the overall cross-sectional mass balance relationship under conditions of significant dynamic environmental fluctuations, hindering further improvement in the overall accuracy of total sediment flux measurement.

[0004] Therefore, how to solve the technical problems caused by the independent calculation of sediment components in existing technologies, such as calculation loop inconsistencies, distortion of physical field space reconstruction, and insufficient adaptability under varying dynamic environments, has become a common challenge that urgently needs to be addressed in the field of cross-sectional sediment monitoring. It is necessary to study a calculation method that can improve the accuracy and robustness of cross-sectional total sediment flux measurement under complex working conditions. Summary of the Invention

[0005] Therefore, this application provides a method for calculating cross-sectional sediment flux, which can achieve adaptive calculation of sediment transformation under different aquatic environments, effectively improve the accuracy of total sediment flux measurement under complex working conditions, and has important engineering application value.

[0006] According to one aspect of this application, a method for calculating cross-sectional sediment flux includes:

[0007] Acquire basic data for the target cross section, including topographic parameters, water flow parameters, sediment parameters, and environmental parameters;

[0008] Based on the basic data, parameter space interpolation is performed to construct a continuous distribution field of cross-sectional flow velocity and a continuous distribution field of cross-sectional sediment concentration.

[0009] Based on the continuous distribution field of cross-sectional velocity, the continuous distribution field of cross-sectional sediment concentration, and environmental parameters, the suspended sediment transport parameters of the cross-section are calculated.

[0010] Based on the basic data, calculate the bedload transport parameters of the cross section;

[0011] Based on the mass conservation principle, the cross-sectional suspended sediment transport parameters and cross-sectional bedload transport parameters are simultaneously corrected in two directions using the exchange coefficient that varies with space, so as to obtain the corrected cross-sectional suspended sediment transport parameters and corrected cross-sectional bedload transport parameters.

[0012] Based on the corrected suspended sediment transport parameters and the corrected bedload transport parameters of the cross section, the total sediment flux of the target cross section is synthesized and output.

[0013] Optionally, the vertical interpolation process for constructing the continuous distribution field of sediment concentration in the cross section includes:

[0014] The reference elevation is determined based on the sediment particle size and the water depth in the topographic parameters.

[0015] Obtain the sand content at the reference elevation;

[0016] A sediment concentration distribution model based on flocculation effective settling velocity correction was adopted, and the sediment concentration at the reference elevation and the corrected Rouse number were combined to calculate the sediment concentration distribution at each vertical depth of the target section.

[0017] Optionally, the lateral interpolation process for constructing the continuous distribution field of cross-sectional velocity and the continuous distribution field of cross-sectional sediment concentration includes:

[0018] Obtain the vertical average parameters corresponding to each velocity measuring line;

[0019] The vertical average parameters are fitted laterally using the first boundary cubic spline function;

[0020] In the fitting process, the spline function is forced to satisfy the third derivative continuity at the second and penultimate nodes near the two ends of the cross section by using non-node end conditions, thus obtaining the continuous distribution field of the entire cross section.

[0021] Optionally, calculate the suspended sediment transport parameters of the cross-section, including:

[0022] Spatial integration of the continuous distribution field of cross-sectional velocity and the continuous distribution field of cross-sectional sediment concentration yields the basic suspended sediment transport rate.

[0023] Based on the environmental parameters of temperature and salinity, the environmental correction coefficient is calculated using a preset environmental coupling correction function.

[0024] The suspended sediment transport parameters of the cross section are obtained by weighting the basic suspended sediment transport rate using environmental correction coefficients.

[0025] Optionally, calculate the bedload transport parameters of the cross-section, including:

[0026] Obtain the cross-sectional average flow velocity of the target section at each lateral coordinate.

[0027] The density difference term is calculated based on the sediment density in the sediment parameter and the water density in the environmental parameter.

[0028] The instantaneous bedload transport rate per unit width at each lateral coordinate is obtained by multiplying the density difference term, the sediment particle size in the sediment parameters, the difference between the cross-sectional average flow velocity and the sediment initiation velocity, the ratio of the cross-sectional average flow velocity to the sediment initiation velocity, and the ratio of the sediment particle size to the water depth in the topographic parameters.

[0029] Optionally, the initial flow velocity of sediment is determined in the following way:

[0030] The equivalent roughness height is determined based on the particle size of the sediment.

[0031] A logarithmic calculation term is constructed using the equivalent roughness height and water depth;

[0032] By combining logarithmic calculation terms with explicit calculations, the sediment initiation velocity corresponding to different water depths is obtained.

[0033] Optionally, the exchange coefficient can be used to perform bidirectional synchronous correction of the suspended sediment transport parameters and the bedload transport parameters of the cross section, including:

[0034] Calculate the suspended exchange amount based on the exchange coefficient and cross-sectional bedload transport parameters;

[0035] The suspended sediment transport parameters of the cross section are added to the suspended exchange rate to obtain the corrected suspended sediment transport parameters of the cross section.

[0036] Subtracting the suspended exchange rate from the cross-sectional bedload transport parameters yields the corrected cross-sectional bedload transport parameters.

[0037] Among them, the sum of the corrected cross-sectional suspended sediment transport parameters and the corrected cross-sectional bedload transport parameters is equal to the sum of the parameters of the two before the correction.

[0038] Optionally, when the target section is located in a tidal-controlled area, after outputting the total sand flux of the section, the following is also included:

[0039] The total sediment flux at the cross section was decomposed using the flux mechanism decomposition method to obtain the horizontal flux contribution term and the tidal pump flux contribution term, so as to quantify the contribution ratio of different sediment transport mechanisms to the total flux.

[0040] Optionally, when calculating the density difference term, the water density is determined in real time based on the environmental parameters of temperature and salinity, using a preset density lookup table or fitting function.

[0041] Optionally, the threshold for sediment particle size is a dynamically determined, non-fixed value;

[0042] Specifically, based on the measured water flow intensity and sediment settling characteristics, the particle size division boundary between suspended and bedloaded sediments under the current operating conditions is dynamically identified. Attached Figure Description

[0043] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0044] Figure 1 This is a schematic diagram of a method for calculating cross-sectional sediment flux provided in this application.

[0045] Figure 2 This is a schematic diagram of the process for constructing a continuous distribution field of sand content in the cross section provided in this application.

[0046] Figure 3 This is a schematic diagram of the vertical interpolation process in the continuous distribution field of sediment content in the construction section provided in this application.

[0047] Figure 4 This is a schematic diagram of the calculation process for suspended sediment transport parameters at the cross-section provided in this application.

[0048] Figure 5 This is a schematic diagram of the process for bidirectional synchronous correction of cross-sectional suspended sediment transport parameters and cross-sectional bedload transport parameters using the exchange coefficient provided in this application. Detailed Implementation

[0049] Unless otherwise specified, in the embodiments of the present invention:

[0050] g _b_y_t g b (y,t) represent the instantaneous sediment transport rate per unit width at each lateral coordinate.

[0051] U _c_prime U c 'These all represent the initial flow velocity of sediment;'

[0052] C avg , All of these represent the average sand content of the cross section.

[0053] Example 1

[0054] This embodiment provides a method for calculating cross-sectional sediment flux, such as... Figure 1 As shown, the method may include the following steps:

[0055] Step 101: Obtain basic data of the target section, including topographic parameters, water flow parameters, sediment parameters, and environmental parameters.

[0056] Specifically, target cross-sections are typically selected in waterways such as rivers, estuaries, reservoirs, or pumping station navigation channels where sediment monitoring is required. Topographic parameters may include the cross-sectional water surface width B and the water depth h(y) corresponding to each lateral coordinate y, as measured by a depth sounder. Flow parameters are obtained using Doppler current meters along a vertically arranged line along the cross-section, including the instantaneous velocity u(y,z,t) (t being time) at different relative water depths z / h (z being the vertical coordinate) and the instantaneous flow rate Q(t). Sediment parameters are obtained through synchronous sampling using a sampler, and may include the instantaneous sediment concentration c(y,z,t) and sediment particle size d at different relative water depths. For complex waterways involving estuaries or tidal zones, environmental parameters also include water temperature T and salinity S. Obtaining this multi-dimensional basic data provides a data foundation for subsequently constructing a high-precision continuous distribution field.

[0057] Step 102: Perform parameter space interpolation based on the basic data to construct a continuous distribution field of cross-sectional flow velocity and a continuous distribution field of cross-sectional sediment concentration. That is, perform parameter space interpolation based on topographic parameters, water flow parameters, sediment parameters and environmental parameters to construct a continuous distribution field of cross-sectional flow velocity and a continuous distribution field of cross-sectional sediment concentration.

[0058] The continuous distribution fields of cross-sectional velocity and sediment concentration typically refer to the continuous numerical distributions of velocity and sediment concentration formed in the two-dimensional space of the target cross-section in the transverse and vertical directions. Specifically, the cross-section is divided into n sub-sections according to the transverse position of the velocity measurement vertical line. For interpolation in the vertical dimension, the velocity is usually calculated using a logarithmic function interpolation method, while the sediment concentration is calculated using a model corrected for the effective settling velocity after flocculation. For interpolation in the transverse dimension, a cubic spline function with non-node end constraints is used to fit the vertical average parameters of each vertical line.

[0059] The aforementioned spatial interpolation method transforms discrete data from a limited number of measuring points into a continuous parameter field covering the entire cross section, effectively reducing the calculation deviation caused by excessive vertical spacing in the traditional block weighting method, thereby reproducing the spatial distribution characteristics of water flow and sediment.

[0060] Step 103: Calculate the suspended sediment transport parameters of the cross section based on the continuous distribution field of cross section velocity, the continuous distribution field of cross section sediment concentration, and environmental parameters.

[0061] In this embodiment, the suspended sediment transport parameters at the cross-section specifically include the instantaneous suspended sediment transport rate and the total flux over a given period. Specifically, the basic suspended sediment transport rate is obtained by performing vertical integration and lateral summation on the continuous distribution fields of velocity and sediment concentration at the cross-section in the cross-sectional space. Furthermore, a weighted correction coefficient k1 based on pre-fitted environmental parameters such as temperature and salinity is used to correct the basic transport rate. This three-level calculation model, coupled with environmental coupling correction, effectively quantifies the impact of temperature and salinity factors on sediment flocculation and settling velocity in complex environments such as estuaries, thereby improving the accuracy of suspended sediment flux measurement.

[0062] Step 104: Calculate the cross-sectional bedload transport parameters based on the basic data, namely the topographic parameters, water flow parameters, sediment parameters, and environmental parameters.

[0063] In some embodiments, the bedload transport parameters of the cross section are calculated based on the continuous distribution field of cross-sectional velocity, topographic parameters, and sediment parameters.

[0064] The bedload transport parameters at the cross-section include the instantaneous bedload transport rate and the total flux over a given period. In practice, the bedload transport width B' is determined based on sediment particle size and flow parameters; this width represents the actual lateral range of bedload movement within the cross-section. Within this transport width, a modified formula with dimensionless consistency is used to calculate the instantaneous bedload transport rate per unit width. This formula comprehensively considers the density difference between sediment and water, the average flow velocity at the cross-section, and the initial sediment velocity. The instantaneous bedload transport rate at the cross-section is then synthesized through lateral integration.

[0065] Based on a physical mechanism and a dimensionless calculation method, this method solves the problem of poor universality of traditional empirical formulas and can be adapted to different particle sizes and water flow conditions.

[0066] Step 105: Based on the mass conservation principle, the suspended sediment transport parameters and bedload transport parameters of the cross section are synchronously corrected in both directions using a preset exchange coefficient that varies with space, so as to obtain the corrected suspended sediment transport parameters and the corrected bedload transport parameters of the cross section.

[0067] The mass conservation criterion states that the total sand flux remains constant before and after correction. The exchange coefficient k3 is a coefficient that dynamically changes with the transverse coordinate of the cross section and time, representing the conversion intensity between suspended and bedload.

[0068] Specifically, the exchange coefficient is used to synchronously correct both the suspended sediment transport parameters and the bedload transport parameters of the cross-section, such as... Figure 5 As shown, the calculation process is as follows:

[0069] The suspended sediment transport volume is calculated based on the exchange coefficient and the cross-sectional bedload transport parameters. Specifically, the suspended sediment transport volume is calculated by multiplying the exchange coefficient k3 by the cross-sectional bedload transport parameters. The cross-sectional suspended sediment transport parameters are then added to the suspended sediment transport volume to obtain the corrected cross-sectional suspended sediment transport parameters. Correspondingly, the suspended sediment transport volume is subtracted from the cross-sectional bedload transport parameters to obtain the corrected cross-sectional bedload transport parameters. The sum of the corrected cross-sectional suspended sediment transport parameters and the corrected cross-sectional bedload transport parameters is equal to the sum of the two parameters obtained before the correction.

[0070] This bidirectional synchronous correction mechanism simulates the dynamic equilibrium of sediment at the bed surface interface in nature, i.e., the conversion of suspended sediment into bedload or the resuspension of bedload into suspended sediment. By introducing a modified Rouse number that varies with spatial location to dynamically determine the exchange coefficient, adaptive calculation of suspended-bedload conversion can be achieved. Because a one-addition-one-subtraction logic is used when calculating the corrected parameters, the total synthesized amount before and after correction is consistent.

[0071] Step 106: Based on the corrected suspended sediment transport parameters and the corrected bedload transport parameters of the cross section, synthesize and output the total sediment flux of the target cross section.

[0072] Specifically, the corrected suspended sediment transport parameters and the corrected bedload transport parameters of the cross-section are summed to obtain the instantaneous sediment transport rate curve of the target cross-section and the total flux value over the time period. The final output can include a dynamic curve of the instantaneous sediment transport rate over time, a statistical table of individual fluxes, and an accuracy verification report. By outputting multi-dimensional measurement results, accurate data support can be provided for water conservancy project design, river regulation assessment, and water environment management.

[0073] Example 2

[0074] Based on the above embodiment 1, this embodiment further describes in detail the data reconstruction process in scenarios with data shortage or limited monitoring conditions.

[0075] In one possible implementation, when acquiring basic data for the target cross-section, if real-time measured data is missing, a continuous distribution field of sediment concentration in the cross-section is constructed as follows: A correlation model is established between the sediment concentration of a single sample and the average sediment concentration of the cross-section using real-time collected individual sample sediment concentrations and pre-stored historical measured data; based on the correlation model, the average sediment concentration of the target cross-section is estimated using the individual sample sediment concentrations; using a preset allocation model, the average sediment concentration of the cross-section is numerically allocated in the vertical and horizontal directions to obtain a continuous distribution field of sediment concentration in the cross-section, such as... Figure 2 As shown.

[0076] In this embodiment, the data shortage scenario specifically refers to a situation where, due to severe hydrological weather, partial damage to monitoring equipment, or geographical limitations of the monitoring station, it is difficult to perform synchronous sampling on all preset vertical lines of the target cross section. Under this condition, a single sample of sediment concentration is collected by selecting a representative fixed measuring point within the cross section, and the deficiencies of real-time spatial monitoring are compensated for by utilizing historically accumulated patterns.

[0077] Specifically, the process of establishing the correlation model includes: extracting the single-sample sediment concentration sequence and the corresponding average sediment concentration sequence of the target cross-section collected synchronously during historical periods. The average sediment concentration sequence is the true value calculated from historical full-section intensified monitoring data using a flow-weighted average. Statistical regression analysis is then used to perform correlation analysis on the two sets of sequences to determine the mapping relationship between them.

[0078] In a preferred embodiment, the association model can take the form of a linear regression equation:

[0079] C avg =a'*C s +b;

[0080] Among them, C avg To deduce the average sediment content of the cross-section; C s denoted as , where is the real-time collected single-sample sediment content; a' is the regression coefficient; and b is the regression constant.

[0081] In other alternative implementations, for water bodies where sediment concentration fluctuates drastically with flow rate, the correlation model can also adopt a power function or exponential function form to improve the robustness of the fit under extremely high sediment concentration conditions. Typically, a goodness-of-fit R-value of the correlation model is required. 2 ≥0.9, to ensure the reliability of subsequent flux calculations.

[0082] After obtaining the cross-sectional average sediment concentration, the allocation model performs the operation of restoring the point data to a spatial field. Specifically, the vertical allocation process uses the modified Rouse sediment concentration distribution model mentioned in the previous embodiment, with the derived cross-sectional average sediment concentration as a constraint operator, to determine the reference sediment concentration value at the reference elevation, thereby calculating the sediment concentration distribution of each velocity measuring vertical at different relative water depths.

[0083] Correspondingly, the lateral allocation process utilizes a cubic spline function with non-node end constraints to perform lateral smoothing interpolation of the average sediment concentration of each vertical line generated by the vertical allocation. During this process, the model dynamically fine-tunes the interpolation weights based on historically measured lateral velocity distribution characteristics, ultimately constructing a continuous distribution field of cross-sectional sediment concentration that conforms to hydraulic characteristics.

[0084] The reconstruction mechanism based on single-sample data can generate a spatial field of sediment content with physical meaning even under low-frequency or low-density monitoring conditions. This effectively solves the problem in existing technologies where single-point measurements are insufficient to reflect the uneven distribution of sediment across a cross-section, reducing the labor intensity and economic cost of fieldwork while ensuring measurement accuracy.

[0085] Furthermore, as another form of the above scheme, the allocation model can also be optimized by combining the measured cross-sectional shear stress distribution. Specifically, the magnitude of shear stress at each lateral position is calculated in real time, and the corrected Rouse number of the corresponding vertical line is adjusted accordingly, so that the reconstructed sediment load field can more sensitively capture high sediment areas caused by abrupt changes in local riverbed topography.

[0086] In another alternative implementation, for estuary sections significantly affected by tides, the correlation model can incorporate the rate of water level rise and fall as a correction factor. By analyzing the drift patterns of representative samples during tidal cycles, the regression coefficient 'a' is corrected across different time periods, further reducing measurement errors during complex alternating hydrological conditions.

[0087] Example 3

[0088] Based on the above embodiments 1 and 2, this embodiment further details the vertical and horizontal high-precision interpolation links in constructing the continuous distribution field of cross-sectional flow velocity and the continuous distribution field of cross-sectional sediment content.

[0089] One possible implementation is, such as Figure 3 As shown, the vertical interpolation process for constructing the continuous distribution field of sediment concentration in a cross-section includes: determining the reference elevation based on the sediment particle size and water depth in the topographic parameters; interpolating the measured sediment concentration data closest to the reference elevation based on the sediment parameters to obtain the sediment concentration at the reference elevation; calculating the corrected Rouse number based on the sediment particle size in the sediment parameters, the frictional velocity in the flow parameters, and the environmental parameters; and using a sediment concentration distribution model corrected based on the effective settling velocity of flocculation, combined with the sediment concentration at the reference elevation and the corrected Rouse number, calculating the sediment concentration distribution of the target cross-section at each vertical depth.

[0090] Specifically, vertical interpolation is used to determine the continuous variation characteristics of sediment concentration from the riverbed to the water surface along each velocity measurement vertical line. Since the distribution of sediment in water is influenced by both gravitational settling and turbulent diffusion, its vertical distribution exhibits a high degree of nonlinearity. In this embodiment, the reference elevation is a characteristic height used to define the sediment exchange state near the bed surface, serving as the physical starting point for calculating the sediment concentration distribution along the entire vertical line. The sediment concentration at the reference elevation is typically obtained by linear or nonlinear interpolation of the measured data from the nearest point to the reference elevation.

[0091] Furthermore, the sediment concentration distribution model based on the correction for effective settling velocity caused by flocculation is an improvement upon the traditional Rouse theory. Because fine-grained sediment undergoes flocculation in estuaries or high-sediment-content waters, its actual settling velocity deviates from the physical settling velocity of a single particle. Therefore, introducing a flocculation correction term can more accurately reflect the motion characteristics of particle clusters. The sediment concentration distribution model incorporates a spatially distributed correction Rouse number Z. R * To characterize the gradient of sediment distribution.

[0092] Corrected Rouse number Z R * The calculation method is as follows:

[0093] Z R * =ω eff / (κ·u * );

[0094] Among them, Z R * To correct the Rouse number; ω eff κ represents the effective settling velocity of sediment flocculation; κ is the von Kármán constant, with a value of 0.4; u * The local frictional velocity at the cross section is obtained by converting the average velocity at water depth to the Chevron coefficient.

[0095] Effective settling rate ω of flocculation eff The flocculation correction factor ffloc is determined based on the product of the sediment particle settling velocity ω0 and the flocculation correction factor ffloc.

[0096] ω eff =ω0×ffloc;

[0097] The single-particle settling velocity ω0 is calculated based on the sediment particle size d using the Stokes settling velocity formula or the Dietrich empirical formula. The flocculation correction factor ffloc is determined based on the salinity in the environmental parameters through a preset empirical relationship. In this embodiment, ffloc is set to 1.3. For pure freshwater scenarios without salinity influence, ffloc is set to 1.0, in which case the corrected Rouse number degenerates into the classic Rouse number.

[0098] By calculating the geometric relationship between the corrected Rouse number and relative depth, the instantaneous sediment concentration at different water levels can be accurately deduced.

[0099] In one possible embodiment, determining the reference elevation includes comparing a multiple of the sediment particle size with a preset ratio of the water depth, and selecting the larger value as the reference elevation for the corresponding spatial location.

[0100] Specifically, to ensure that the selected reference elevation reflects both the movement space of coarse particles at the bottom layer and is suitable for physical field calculations in deep water areas, this embodiment employs dynamic discrimination logic. When determining the reference elevation, the system calculates twice the sediment particle size in real time and simultaneously calculates a value 0.05 times the water depth. By comparing the two values, the larger value is selected as the reference elevation.

[0101] a(y,t)=max(2*d,0.05*h(y));

[0102] Where a(y,t) is the reference elevation at time t at the horizontal coordinate y; d is the particle size of the sediment; and h(y) is the water depth at the corresponding horizontal coordinate.

[0103] The aforementioned dynamic discrimination method effectively addresses the problem of singular values ​​or physical distortions in mathematical models caused by excessively small reference elevations in shallow water areas or under conditions of extremely fine particles. For example, when the sediment particle size is very small, the reference elevation is determined by the water depth ratio, ensuring the physical width of the bottom mixing layer; while when the water depth is shallow and the particles are coarse, it is determined by the particle size multiple, ensuring that the surface roughness directly constrains the sediment distribution. This improves the stability of the vertical interpolation model under different hydrodynamic conditions.

[0104] In one optional embodiment, the lateral interpolation process for constructing the continuous distribution field of cross-sectional velocity and the continuous distribution field of cross-sectional sediment concentration includes: performing depth-weighted average calculations on the vertical velocity of each velocity measurement line in the flow parameters and the vertical sediment concentration of each velocity measurement line in the sediment parameters to obtain the vertical average parameters corresponding to each velocity measurement line; and using a first boundary cubic spline function to perform lateral fitting on the vertical average parameters (in this embodiment, the first derivative values ​​of the endpoints required by the first boundary conditions are automatically determined by the non-node end conditions, without the need for manual specification); wherein, during the fitting process, the non-node end conditions are used to force the spline function to satisfy the continuity of the third derivative at the second node and the penultimate node near both ends of the cross-section, thereby obtaining the continuous distribution field of the entire cross-section.

[0105] The vertically averaged parameter refers to the cross-sectional parameter obtained by performing a depth-weighted integral on the interpolation results for each velocity measurement vertical line. After obtaining the discretely distributed average flow velocity or average sediment concentration for each vertical line, it is necessary to extend it to the entire cross-sectional width range through lateral interpolation. The first boundary cubic spline function used in this embodiment is a piecewise cubic polynomial interpolation method, which has excellent smoothness with continuous global second derivative.

[0106] In this embodiment, due to the complex boundary conditions on both sides of the river channel, traditional natural boundary conditions (i.e., the second derivative at the endpoints is 0) or clamping boundary conditions (i.e., the first derivative at the endpoints is a known value) often fail to accurately reflect the flow characteristics near the bank slope. Therefore, this embodiment introduces non-node end condition constraints. Non-node end conditions refer to forcing the spline function to maintain the continuity of its third derivative at the second and penultimate nodes near both ends of the cross-section by extending the cubic polynomial continuity of adjacent interior points.

[0107] Therefore, the interpolation system can determine the spline function expression of the entire cross section without requiring additional assumptions about boundary derivatives. This technique can automatically adapt to the edge morphology of irregular cross sections such as estuaries and meandering channels, effectively solving the numerical oscillation problem caused by abrupt changes in flow velocity or uneven distribution of sediment concentration along the bank, and ensuring the physical consistency and numerical stability of the generated continuous distribution field of flow velocity and sediment concentration in the transverse direction.

[0108] In an alternative implementation, for water bodies with a cross-sectional width greater than 100 meters and relatively irregular topography, the density of velocity measuring verticals can be increased, and combined with the aforementioned non-nodal end conditional spline interpolation, a locally high-precision fitting surface with multi-node constraints can be constructed to further capture subtle flow field changes in the deep trench region. Simultaneously, the computational residuals generated during the lateral interpolation process can serve as a reference for subsequent accuracy verification steps.

[0109] By introducing cubic spline interpolation with non-node end condition constraints in the parameter field construction process, the problem of data reconstruction distortion near the cross-section edge and bank slope is effectively solved, and the parameter field is transformed from discrete points to a continuous spatial field with high precision, providing a robust basic data environment for flux calculation.

[0110] Example 4

[0111] Based on the above determination of the cross-sectional topographic structure, the continuous distribution field of velocity, and the continuous distribution field of sediment concentration, the environmental coupling correction logic involved in the calculation of the suspended sediment transport parameters of the cross-section is further explained in detail.

[0112] One possible implementation, such as Figure 4 As shown, the process of calculating the suspended sediment transport parameters of the cross-section includes:

[0113] Spatial integration is performed on the continuous distribution fields of cross-sectional velocity and sediment concentration to obtain the basic suspended sediment transport rate. Based on the environmental parameters of temperature and salinity, the environmental correction coefficient is calculated using a preset environmental coupling correction function. The basic suspended sediment transport rate is then weighted and corrected using the environmental correction coefficient to obtain the cross-sectional suspended sediment transport parameters.

[0114] Specifically, the calculation of suspended sediment transport parameters at the cross-section follows a three-level model: vertical integration, lateral summation, and time integration. The instantaneous velocity at each coordinate point in the continuous velocity distribution field of the cross-section is multiplied by the instantaneous sediment concentration at the corresponding point in the continuous sediment concentration distribution field of the cross-section, and then integrated vertically along the water depth to obtain the instantaneous suspended sediment transport rate per unit width. The sub-cross-section widths between each velocity measurement vertical are used as weights to laterally accumulate the unit width sediment transport rates, thus synthesizing the basic suspended sediment transport rate for the entire cross-section.

[0115] In this embodiment, the environmental coupling correction function is used to quantify the measurement deviation caused by changes in the hydrological environment in estuaries or nearshore areas. Because the flocculation characteristics of sediment differ significantly under different salinity and temperature conditions, the actual sediment settling velocity deviates from the theoretical distribution. Introducing an environmental correction coefficient k1 can dynamically compensate for the nonlinear deformation of sediment concentration distribution caused by environmental factors.

[0116] Specifically, the environmental correction factor k1 is calculated using a temperature-salinity coupled quadratic polynomial function:

[0117] k1 = a0 + a1*T + a2*S + a3*T 2 +a4*S 2 +a5*T*S;

[0118] Where k1 is the environmental correction coefficient; T is the real-time water temperature; S is the real-time water salinity; and a0, a1, a2, a3, a4, and a5 are pre-fitted coefficients to be calibrated.

[0119] In other alternative implementations, the environment coupling correction function may also take the form of an exponential function or a BP neural network model.

[0120] In practical applications, the aforementioned coefficients to be calibrated are obtained by least squares fitting of historical measured data, and the goodness of fit R is required to be... 2 The salinity is no less than 0.95. For pure freshwater river scenarios where salinity has no effect, the salinity S is set to 0. In this case, the environmental coupling correction function is automatically simplified to a correction polynomial containing only the temperature term, ensuring the algorithm's universality in different aquatic environments.

[0121] After completing the weighted correction of the basic suspended sediment transport rate, the total suspended sediment flux within the target time period can be obtained by further integrating the corrected instantaneous sediment transport rate over time.

[0122] In one alternative implementation, for flash flood channels with drastic flow fluctuations, the calculation of total suspended sediment flux can be simplified using a flow-weighted method. Specifically, a flow-weighting coefficient is determined by fitting a flow change curve over a time period, and the instantaneous sediment transport rate at the cross-section is multiplied by the flow-weighting coefficient at the corresponding moment, and then accumulated over time. This method, while ensuring calculation accuracy, can reduce the data processing overhead caused by high-frequency sampling and improve the real-time feedback capability of the system.

[0123] In another alternative implementation, for estuarine sections affected by tidal currents, the calculation of the basic suspended sediment transport rate needs to consider the sign of the flow direction. That is, during high tide, the transport rate is recorded as positive, indicating sediment transport towards land; during low tide, the transport rate is recorded as negative, indicating sediment transport towards the sea. Finally, by integrating over a complete tidal cycle, the net suspended sediment flux of the section is obtained, providing data support for the analysis of estuarine evolution patterns.

[0124] Example 5

[0125] Based on the above embodiments, the calculation process of cross-sectional bedload transport parameters is further described, focusing on the calculation model with consistent physical dimensions and its parameter adaptation in dynamic environments.

[0126] In one possible implementation, the process of calculating the bedload transport parameters of the cross section includes:

[0127] The depth-averaged vertical velocity at each transverse coordinate in the continuous velocity distribution field of the cross section is calculated to obtain the cross-sectional average velocity at each transverse coordinate of the target section.

[0128] The density difference term is calculated based on the sediment density in the sediment parameter and the water density in the environmental parameter.

[0129] Based on the sediment particle size in the sediment parameters and the water depth in the topographic parameters, the sediment initiation velocity is calculated. The instantaneous bedload transport rate per unit width is obtained by multiplying the density difference term, the sediment particle size in the sediment parameters, the difference between the cross-sectional average velocity and the sediment initiation velocity, the ratio of the cross-sectional average velocity to the sediment initiation velocity, and the ratio of the sediment particle size to the water depth in the topographic parameters. The instantaneous bedload transport rate per unit width is then integrated transversely over the bedload transport width to obtain the cross-sectional bedload transport parameters.

[0130] Specifically, the cross-sectional average velocity U(y) is obtained by depth averaging the vertical velocity at the corresponding transverse coordinate y in the continuous velocity distribution field of the cross-section. In this embodiment, the instantaneous bedload transport rate g per unit width is... _b_y_t The calculation uses the modified Szamov formula:

[0131] g _b_y_t=k2*C0*(ρ s -ρ w )*d*(U(y)-U _c_prime )*(U(y) / U _c_prime ) 3 *(d / h(y)) 1 / 4 ;

[0132] Among them, g _b_y_t ρ is the instantaneous bedload transport rate per unit width at each lateral coordinate; k2 is the preset bedload correction coefficient, which is 1.0 in this embodiment; C0 is the dimensionless Shamov empirical constant, which is 0.27 in this embodiment; ρ s The density of silt is typically taken as 2650 kg / m³ for natural quartz sand. 3 ;ρ w d is the density of the water; d is the particle size of the sediment; U(y) is the average cross-sectional velocity at the lateral coordinate y; U _c_prime denoted as ρ, where ρ is the initial velocity of the sediment flow; h(y) is the water depth at the lateral coordinate y.

[0133] The density difference term is obtained by calculating the difference between the density of sediment and the density of water, and then combined with the velocity difference term (U(y) - U... _c_prime The calculation method, including the addition of nonlinear influence terms, accurately characterizes the transport intensity of sediment on the bed surface under the shearing action of water flow. By introducing density difference and geometric ratio terms, this method ensures that the output results are in units of mass flux, i.e., kilograms per meter per second.

[0134] In one possible embodiment, the sediment initiation velocity is determined by: determining the equivalent roughness height based on the sediment particle size; constructing a logarithmic calculation term using the equivalent roughness height and water depth; determining the critical friction velocity based on the sediment particle size and water density in the sediment parameters; and performing explicit calculation by combining the logarithmic calculation term and the critical friction velocity to obtain the sediment initiation velocity corresponding to different water depths.

[0135] Specifically, the sediment initiation velocity U _c_prime This determines the critical state of bedload motion. In this embodiment, the equivalent roughness height k s The calculation method is as follows: k s =2.5*d; where k s d represents the Nikuradse equivalent roughness height; d is the particle size of the sediment.

[0136] Based on the equivalent roughness height, the critical frictional velocity u is determined using the Soulsby critical Shields numerical formula. *c By combining the logarithmic velocity distribution law, the starting velocity at each vertical position is determined.

[0137] U _c_prime=(u *c / κ)*ln(h(y) / (e*k s ));

[0138] Among them, U _c_prime The initial flow velocity of the sediment; u *c κ is the critical frictional velocity; h(y) is the von Kármán constant; e is the water depth at the corresponding location; and e is the base of the natural logarithm, which is 2.718.

[0139] Critical frictional velocity u *c The calculation formula is as follows:

[0140] ;

[0141] Where, θ c The critical Shields number is γ, which can be found on the Shields curve by calculating the particle Reynolds number or related auxiliary parameters. s =ρ s ·g is the bulk density of the sediment, γ=ρ w ·g is the specific weight of water, g is the acceleration due to gravity, ρ w d represents the density of the water body, and d represents the particle size of the sediment.

[0142] This explicit calculation method avoids human error in traditional graphical methods and can adapt to changes in water depth at different locations within the cross-section in real time.

[0143] In one possible implementation, when calculating the density difference term, the water density is determined in real time based on environmental parameters such as temperature and salinity, using a preset density lookup table or fitting function.

[0144] In this embodiment, considering the unique characteristics of the saline dynamic environment in the estuary area, the water density ρ w It is not a fixed constant. Specifically, the system receives environmental parameters such as temperature (T) and salinity (S) in real time, and retrieves a density lookup table pre-stored in the database, or calls the corresponding state equation fitting function. For example, in freshwater areas, ρ w The value is 1000 kg / m 3 In seawater, density increases with increasing salinity or decreasing temperature. By dynamically determining the water density, the density difference term (ρ) in the formula can be accurately calculated. s -ρ w This eliminates biases in the bedload measurement system caused by environmental changes.

[0145] In one possible implementation, the calculation range of the cross-sectional bedload transport parameters is limited to the bedload transport width; the bedload transport width is determined based on the criterion that the average flow velocity at each transverse coordinate is greater than the sediment initiation velocity; wherein, in the tidal-controlled area, the bedload transport width is dynamically adjusted laterally with the change of the measured tidal level.

[0146] Wherein, the bedload transport width B' refers to the actual effective lateral range within the cross-section where sediment particles slide, roll, or leap along the bed surface. In specific implementation, it is determined based on the real-time flow velocity U(y) and the starting flow velocity U at each lateral coordinate. _c_prime The relationship determines the transport band boundary, that is, only when U(y) > U _c_prime The region implements a sediment transport rate integral.

[0147] In tidal-affected areas, the submerged boundary and deep channel velocity distribution of the cross-section shift significantly with tidal rise and fall. Correspondingly, the bedload transport width B' dynamically adjusts laterally with the measured tidal level. This dynamic boundary control effectively avoids including still water areas or low-velocity shoals in the integration range, ensuring the accuracy of the synthesized instantaneous bedload transport rate. By integrating the instantaneous values ​​over time, the total bedload flux within the time period is obtained.

[0148] Example 6

[0149] Based on the determination of suspended sediment transport parameters and bedload transport parameters in the aforementioned embodiments, this embodiment further elaborates on the implementation method of bidirectional synchronous correction of suspended sediment and bedload based on the mass conservation criterion, solving the problem of logical non-closed loop caused by independent calculation of the two components in the traditional method.

[0150] Step 601: Based on the mass conservation principle, the cross-sectional suspended sediment transport parameters and cross-sectional bedload transport parameters are simultaneously corrected in both directions using the exchange coefficient that varies with space, so as to obtain the corrected cross-sectional suspended sediment transport parameters and the corrected cross-sectional bedload transport parameters.

[0151] Specifically, the mass conservation criterion means that during the execution of the coordinated correction logic, the total flux of all sand in the cross section remains constant. That is, the correction process only changes the distribution ratio of suspended sediment and bedload in the total sand, without changing the total mass. Bidirectional synchronous correction is achieved by introducing exchange quantities.

[0152] In practice, the calculated cross-sectional bedload transport parameters are quantified using the exchange coefficient to determine the sediment flux transferred from the bed layer to the suspended layer, i.e., the suspended bedload exchange rate. The suspended bedload exchange rate is then compensated into the cross-sectional suspended bedload transport parameters, and an equal amount is simultaneously deducted from the cross-sectional bedload transport parameters.

[0153] To further illustrate the physical conservation of this correction process, a simplified normalization example is used below. Assume that at a certain sub-section, the initial suspended sediment transport rate after normalization is 10.0, and the initial bedload transport rate is 1.0. If the calculated exchange coefficient k3 is 0.02, then by calculating the product of the exchange coefficient and the bedload transport rate, the suspended sediment exchange amount is 1.0 * 0.02 = 0.02. After performing bidirectional synchronous correction, the corrected section suspended sediment transport rate is 10.0 + 0.02 = 10.02; simultaneously, the corrected section bedload transport rate is 1.0 - 0.02 = 0.98. Upon verification, the corrected instantaneous total sediment transport rate is 10.02 + 0.98 = 11.0, which is equal to the original total sediment transport rate of 10.0 + 1.0 = 11.0. This simultaneous addition and subtraction ensures that the computation process meets the mass conservation requirements in terms of physical mechanisms.

[0154] In some embodiments, the exchange coefficient is a coefficient that dynamically changes with the transverse coordinate of the cross section and time; the exchange coefficient is calculated based on a preset exchange intensity coefficient and a corrected Rouse number corresponding to the current spatial position; wherein, the corrected Rouse number is calculated based on the sediment particle size in the sediment parameters, the frictional velocity in the flow parameters, and the temperature and salinity in the environmental parameters.

[0155] The exchange coefficient k3 characterizes the vertical exchange intensity between suspended and bedload sediment, and its value is dynamically adjusted according to the lateral distribution of the cross-section and the evolution of sediment-laden water flow conditions. In this embodiment, the exchange coefficient k3 is calculated as follows:

[0156] k3=η*(1-Z R * ) / (1+α*(Z R * -1) 2 );

[0157] Wherein, k3 is the spatially varying exchange coefficient; η is a preset dimensionless exchange intensity coefficient, used to characterize the sediment exchange benchmark intensity of the predetermined water area. In this embodiment, η is set to 0.5, and its specific value can be determined by those skilled in the art through least squares calibration based on historical measured thrust-to-slip ratio data of the target water area. Z R * α represents the corrected Rouse number corresponding to the spatial coordinate position and the current time; α is a preset nonlinear control parameter.

[0158] The nonlinear control parameter α is used to adjust the sensitivity of the exchange coefficient to changes in the modified Rouse number. Its specific value can be determined by those skilled in the art through nonlinear least squares fitting of historical measured thrust-to-suspension ratio data. In an optional embodiment, the value of α is 1.0.

[0159] In one possible implementation, the exchange coefficient is non-linearly mapped to the modified Rouse number when calculating the exchange coefficient. Specifically, when the modified Rouse number is small, the exchange coefficient is positive and decreases as the modified Rouse number increases, indicating a decreasing intensity of sediment conversion from bedload to suspended sediment. When the modified Rouse number exceeds 1, the exchange coefficient becomes negative, indicating a return of suspended sediment to bedload. As the modified Rouse number continues to increase, the absolute value of the exchange coefficient gradually approaches zero, indicating that vertical exchange tends to stop under extreme conditions where sediment is transported entirely as bedload.

[0160] Specifically, the modified Rouse number Z R * The exchange coefficient (k3) is a key physical quantity characterizing the vertical distribution gradient of sediment. The nonlinear mapping between the exchange coefficient and the modified Rouse number reflects the physical mechanism of sediment transport. When the water flow is strong or the sediment particles are fine, the modified Rouse number is small, and the calculated exchange coefficient k3 is large, indicating that bedload is more easily converted into suspended sediment under turbulent diffusion. Conversely, when the modified Rouse number increases, it indicates that the influence of gravity settling on sediment particles is enhanced or the sediment-carrying capacity of the water flow is weakened. At this point, the absolute value of the exchange coefficient k3 gradually approaches zero, indicating that vertical exchange tends to cease.

[0161] By constructing a spatially varying exchange coefficient, this embodiment achieves adaptive adjustment of the suspended sediment conversion coefficient with respect to water flow, sediment, and environmental conditions. Compared to traditional methods that treat suspended and bedload as unrelated independent components, the collaborative correction mechanism provided in this embodiment can more realistically simulate the movement process of the entire sediment within the cross section, solving the problem of large deviations in the calculation of the entire sediment flux under high sediment content or complex terrain cross sections.

[0162] In some alternative implementations, for cross-sections with severe sediment deposition, the exchange intensity coefficient η can be modified, and a riverbed scouring and deposition state feedback factor can be introduced to further refine the sediment exchange logic at the interface. Furthermore, when the modified Rouse number reaches a certain critical threshold, the exchange coefficient can be set to a preset minimum value to simulate the extreme condition where sediment exchange completely ceases.

[0163] It should be noted that in actual calculations, the exchange coefficients calculated based on the locally corrected Rouse number at each lateral coordinate can be first averaged using flow weighting to obtain the cross-sectional comprehensive exchange coefficient. This comprehensive exchange coefficient can then be applied to the integrated cross-sectional bedload transport parameters to simplify the calculation process. Alternatively, those skilled in the art can choose to perform point-by-point suspension correction at each lateral coordinate before integrating and synthesizing the cross-sectional corrected parameters. Both methods satisfy the mass conservation criterion.

[0164] To address the logical conflicts caused by the independent calculation of sediment components in traditional schemes, this invention utilizes an exchange coefficient that dynamically changes with spatial location to perform bidirectional synchronous correction. This mechanism physically simulates the sediment transformation law at the bed surface interface, ensuring that the total sediment flux before and after correction is strictly conserved, and reducing the measurement system deviation caused by the non-closed-loop logic of the algorithm.

[0165] Example 7

[0166] Based on the cross-sectional sediment flux calculation system described in Examples 1 to 6 above, this example further details the flux mechanism decomposition method for complex dynamic environments such as estuaries and tidal-controlled areas.

[0167] In one possible implementation, when the target section is located in a tidal-controlled area, after outputting the total sediment flux of the section, the method further includes: decomposing the total sediment flux of the section using a flux mechanism decomposition method to obtain the horizontal flux contribution term and the tidal pump flux contribution term, so as to quantify the contribution ratio of different sediment transport mechanisms to the total flux.

[0168] Specifically, tidal-controlled areas refer to estuarine or tidal river sections subjected to both runoff and tidal forces. In these areas, sediment transport depends not only on the average flow motion but also on mechanisms such as the nonlinear coupling of velocity and sediment load within the tidal cycle, the tidal pump effect, and density flow. To further analyze the net sediment transport characteristics, this embodiment introduces the Dyer flux mechanism decomposition method, which integrally decomposes instantaneous flux over one or more complete tidal cycles.

[0169] In this embodiment, the average flow flux contribution term reflects sediment migration caused by the average cross-sectional flow, while the tidal pump flux contribution term reflects net sediment transport caused by the correlation between water level, velocity, and sediment concentration fluctuations during the tidal cycle. By decomposing the total sediment flux of the cross-section into components with different physical meanings, the dynamic response characteristics of sediment during the ebb and flow of tides can be quantitatively analyzed.

[0170] Specifically, the flux mechanism is decomposed as follows:

[0171] S net =S1+S2+S3+S4+S5+S6+S7;

[0172] Among them, S net S1 represents the total net sediment flux of the cross section within one tidal cycle; S2 represents the convection term caused by the average flow rate, which is classified as the mean flow flux contribution term; S3 represents the term related to tidal level and flow velocity, i.e., the Stokes drift term; S4 represents the term related to tidal level and sediment concentration; S5, S6, and S7 represent the residual terms of the interaction between each component.

[0173] In practical applications, such as at a tidal estuary section, the specific flux composition can be obtained by collecting and decomposing data from a complete 12-hour tidal cycle. If the calculation results show that the advection flux contribution is 172.5t and the tidal pump flux contribution is 22.8t, it can be determined that sediment transport during this period is mainly driven by advection, with the tidal pump effect providing an additional contribution of about 12%.

[0174] By decomposing the data, not only are numerical values ​​of the total flux provided, but the physical dynamic mechanisms of sediment transport are also revealed. For example, by comparing the proportions of each contributor under different seasons or tidal patterns, it is possible to determine whether the sediment at this cross-section exhibits a seaward transport trend or a landward deposition trend. This has significant scientific guiding value for estuarine channel management, saltwater intrusion early warning, and estuarine delta evolution analysis.

[0175] Furthermore, in some alternative implementations, for density flow regions with significant salinity gradients, the decomposition process can further extract the vertical shear term caused by vertical velocity shear and sediment concentration gradient, thereby quantifying the contribution of vertical circulating flow to net sediment flux.

[0176] In addition, for scenarios with long data sequences, long-term time-series decomposition across tidal cycles can be performed to analyze the trend evolution of sediment transport mechanisms under different dynamic dominance during the wet and dry seasons.

[0177] Accordingly, in addition to the total net flux, the output of this embodiment also includes a flux component ratio chart and a sediment transport mechanism analysis report, providing users with a deeper level of decision-making support. By modularizing the analysis of complex physical transport processes, this embodiment enhances the professional depth and adaptability of the invention in tidal waters.

[0178] Example 8

[0179] Based on the above embodiments 1 to 7, the accuracy verification feedback mechanism of the measurement system, the preprocessing of key correction coefficients, and the dynamic identification process of sediment particle size threshold are further described to achieve closed-loop control and accuracy optimization of the entire process.

[0180] In one possible implementation, after synthesizing the total sediment flux of the target section, an accuracy verification step is also included: obtaining the measured sediment transport rate obtained by directly sampling a local area of ​​the target section; comparing the measured sediment transport rate with the corresponding corrected suspended sediment transport parameters and corrected bedload transport parameters to obtain the calculation relative error; determining whether the calculation relative error is greater than a preset accuracy threshold; if it is greater than the preset accuracy threshold, then recalibrating at least one of the environmental correction coefficient, the bedload correction coefficient in the product operation, and the exchange coefficient according to the calculation relative error to obtain updated coefficients for use in flux calculation in subsequent time periods.

[0181] Specifically, the accuracy verification step is used to quantitatively assess the reliability of the calculation results. After synthesizing the total sediment flux, the measured sediment transport rate is obtained by directly sampling a representative velocity measurement vertical line within the cross section. For example, using vertical lines at y=20m, 40m, and 60m as verification points, the suspended sediment concentration and bedload capture at these points are measured using a sampler, and the corresponding measured sediment transport rate is then calculated.

[0182] E _rel =|Q _calc -Q _meas | / Q _meas ;

[0183] Among them, E _rel To calculate the relative error; Q _calc For the corresponding points, the corrected cross-sectional suspended sediment transport parameters or the corrected cross-sectional bedload transport parameters; Q _meas This represents the measured sediment transport rate at the corresponding location.

[0184] In this embodiment, the preset accuracy threshold used in the determination process is set to 5%. If the relative calculation error is greater than 5%, the applicability of the current correction coefficient is deemed insufficient, and a recalibration command is automatically triggered. The calibration process adjusts the values ​​of the environmental correction coefficient k1, the bedload correction coefficient k2, and the exchange coefficient k3 to reduce the relative calculation error in subsequent time periods to within 5%. This closed-loop feedback mechanism helps improve the robustness of the measurement system under drastic changes in water conditions.

[0185] In one possible implementation, the threshold for sediment particle size is a dynamically determined, non-fixed value; specifically, based on the measured water flow intensity and sediment settling characteristics, the particle size boundary between suspended and bedload under the current operating conditions is dynamically identified.

[0186] The particle size division boundary between suspended and bedload in sediment parameters is a dynamically determined, non-fixed value. Specifically, based on the frictional velocity in the flow parameters and the sediment settling velocity calculated based on the sediment particle size in the sediment parameters, the particle size division boundary between suspended and bedload under the current working conditions is dynamically identified. The particle size division boundary is used to determine the calculation range of the suspended sediment transport parameters and the bedload transport parameters of the cross section.

[0187] In this embodiment, the particle size classification boundary no longer relies on a fixed 0.05mm reference value. Specifically, the system acquires the instantaneous flow velocity from the water flow parameters and the sediment settling velocity from the sediment parameters in real time. The motion state of the sediment particles is determined by calculating the ratio of the local water flow shear stress to the critical shear stress of the sediment, i.e., the Shields parameter.

[0188] When the probability of a certain particle size of sediment being suspended in the current flow field exceeds a preset confidence level, that particle size is dynamically classified as suspended matter. Specifically, whether sediment particles have entered a suspended state can be determined by comparing the frictional velocity u. * The ratio of u to sediment settling velocity ω is used to determine when u is used to determine sediment settling velocity ω. * When the velocity (ω) exceeds a preset threshold (typically a threshold value in the range of 0.8 to 1.2 in the art), the sediment particle size is determined to be in a suspended state. Those skilled in the art can determine the specific threshold value based on the sediment movement characteristics of the target water area and well-known sediment initiation and suspension discrimination criteria. Conversely, if the sediment mainly moves near the bed layer and does not diffuse into the water body, it is classified as bedload. The preset confidence level can be determined by those skilled in the art based on the sediment movement characteristics under actual working conditions. This dynamic identification mechanism can effectively address the problem of blurred boundaries between suspended and bedload components in high-sediment-laden water flows or non-uniform sediment scenarios, providing more physically accurate component input data for subsequent steps.

[0189] In one possible implementation, the coefficients to be calibrated in the environmental coupling correction function and the exchange coefficients involved in the weighted correction of the basic suspended sediment transport rate in the environmental correction coefficient are obtained through the following preprocessing method: acquiring historical measured data of the target section or similar water bodies; fitting the historical measured data using the least squares method to determine the coefficients to be calibrated in the environmental coupling correction function, thus obtaining the calculation model of the environmental correction coefficient; and determining the initial values ​​of the bedload correction coefficient and the exchange coefficient based on the sampling calibration results in the historical measured data.

[0190] Specifically, the preprocessing method improves the accuracy of initial values ​​for real-time calculations by utilizing long-term accumulated data patterns. First, historical measured data is extracted from the database, including the distribution field of sediment concentration across the entire cross-section under different tidal levels and flow rates, as well as the corresponding measured sediment transport rates.

[0191] When determining the environmental correction coefficient k1, the least squares method is used to perform regression fitting on historically measured temperature, salinity, and sediment transport deviation to solve for each coefficient to be calibrated in the polynomial, and the goodness of fit R is required. 2 ≥0.95.

[0192] In this embodiment, in dealing with complex dynamic environments, by introducing a temperature-salinity coupling correction function and dynamic particle size threshold identification technology, the present invention can sensitively capture the influence of flocculation in the estuary on the distribution of sediment concentration, enabling the calculation model to adapt to the working conditions of tidal zones and high sediment concentration flows, and controlling the relative error of the total sediment flux calculation to within 5%.

[0193] According to one aspect of this application, a method for calculating cross-sectional sediment flux further includes the following steps:

[0194] Step 1: Obtain basic cross-sectional parameters and measured data. Select the target cross-section and obtain its basic topographic parameters, flow parameters, sediment parameters, and environmental parameters, specifically including:

[0195] Basic topographic parameters: The water surface width B and the water depth h(y) corresponding to each lateral coordinate y are obtained by actual measurement using a depth sounder, and the topographic profile of the cross section is constructed.

[0196] Flow parameters: The instantaneous flow velocity u(y,z,t) at different relative water depths z / h was measured using a Doppler current meter on the velocity measuring vertical lines arranged along the cross section. At the same time, the instantaneous flow rate Q(t) of the cross section was also measured. The arrangement of the velocity measuring vertical lines followed the principle of uniform distribution with key densification. The vertical lines were densely arranged in areas of abrupt changes in flow velocity (such as the bank and deep channels) to ensure full coverage of the flow velocity distribution.

[0197] Sediment parameters: Sediment samples are taken simultaneously on each velocity measurement vertical line using a sediment sampler to measure the instantaneous sediment concentration c(y,z,t) and sediment particle size d at different relative water depths z / h. The distinction between suspended and bedload is not based on a fixed particle size threshold, but is dynamically determined according to the measured flow conditions and sediment initiation / settling characteristics. In engineering applications, 0.05mm can be used as a preliminary distinction reference, and then corrected based on actual working conditions.

[0198] Environmental parameters: For complex water areas such as estuaries and tidal zones, additional seawater temperature (T) and salinity (S) are measured to correct for the impact of sediment flocculation on settling velocity; for meandering and confluenced channels, additional cross-sectional curvature and tributary inflow are measured to correct for velocity distribution deviations.

[0199] Step 2 involves optimizing the cross-sectional division and parameter interpolation, specifically including:

[0200] Section division: Based on the velocity measuring vertical lines obtained in step 1, the target section is divided into n sub-sections. Two adjacent velocity measuring vertical lines, the bottom of the section, and the water surface enclose a sub-section. The lateral width of the i-th sub-section is Δy. i =y i+1 -y i , where y i y i+1 These are the horizontal coordinates of the i-th and (i+1)-th velocity measuring vertical lines, respectively.

[0201] Vertical parameter interpolation: For each velocity measurement vertical line, logarithmic function interpolation is used to interpolate the flow velocity u(y,z,t) at different relative water depths; sediment concentration is calculated using the Rouse formula, which corrects for the effective settling velocity of flocculation, and the expression is:

[0202] ;

[0203] Where: reference elevation ; The reference sediment concentration at elevation a is obtained by interpolation using data from the nearest measured point to a; To correct the Rouse number, z is the vertical coordinate.

[0204] Lateral parameter interpolation: Using the cubic spline function of the first boundary, the vertical average velocity and vertical average sediment concentration of each velocity measurement line are interpolated laterally to obtain the continuous distribution field of velocity and sediment concentration throughout the cross section; wherein, the endpoint derivative values ​​of the first boundary condition are determined using non-node end conditions (not-a-knot).

[0205] For the boundary points at both ends of the section, by extending the continuity of the cubic spline polynomial of the adjacent interior points, the third derivative of the spline function at the second and penultimate nodes is forced to be continuous, thus uniquely determining the endpoint derivative values;

[0206] This method does not require additional assumptions about endpoint derivatives, avoiding interpolation deviations under complex cross-sectional morphologies under traditional fixed boundary conditions (such as natural boundaries and clamping boundaries), and is suitable for parameter distribution interpolation of irregular cross-sections such as river channels and estuaries.

[0207] Step 3: Calculate the suspended sediment flux using a three-stage calculation model of vertical integration, lateral summation, and time integration, combined with a dynamic correction mechanism, to calculate the instantaneous suspended sediment transport rate and the total flux over a given period:

[0208] Calculate the instantaneous sediment transport rate per unit width of suspended mass: For each velocity measurement vertical line, obtain the instantaneous sediment transport rate q per unit width of suspended mass through vertical integration. si (y,t), the calculation formula is:

[0209] ;

[0210] In the formula: dz is the differential element along the water depth direction (vertical), and k1(T,S) is the environmental coupling correction coefficient, used to correct the influence of sediment flocculation caused by temperature and salinity in the estuary area on the sediment concentration calculation. Its functional form adopts a quadratic polynomial of temperature-salinity coupling:

[0211] ;

[0212] In the formula: T is the water temperature, which can be selected from 0 to 30℃; S is the water salinity, which can be selected from 0 to 35‰; a0, a1, a2, a3, a4, and a5 are coefficients to be calibrated, determined by fitting measured data, and the goodness of fit R is... 2 ≥0.95; For river scenarios where salinity has no effect, S can be 0, and the formula simplifies to a polynomial containing only a temperature term.

[0213] Calculate the instantaneous suspended sediment transport rate of the sub-section: the instantaneous suspended sediment transport rate q of the i-th sub-section. si (t)=qsi (y,t)×Δy i , where q si (y,t) represents the instantaneous suspended sediment transport rate per unit width at the center of the sub-section;

[0214] The instantaneous suspended sediment transport rate of the composite cross-section is obtained by summing the instantaneous suspended sediment transport rates of all sub-sections, resulting in the instantaneous suspended sediment transport rate Q of the cross-section. s (t):

[0215] ;

[0216] Where n represents the total number of sub-sections into which the river cross-section is divided;

[0217] Calculate the total flux of suspended sediment over a given period: This is based on the instantaneous suspended sediment transport rate Q at the cross-section. s (t) is integrated over time to obtain the total suspended mass flux S during time interval T. s :

[0218] ;

[0219] Where dt is the differential element along the time direction;

[0220] In practice, the flow weighting method is used instead of direct integration to reduce the computational difficulty and improve the computational accuracy. The flow weighting coefficients are determined by fitting the flow change curve within a time period.

[0221] Step 4: Calculate the bedload flux, construct a calculation model based on measured calibration, empirical formulas, and collaborative correction, and calculate the instantaneous bedload transport rate and total flux over a given period by combining the interconversion relationship between suspended and bedload:

[0222] Determine the bedload transport zone: Based on the sediment particle size d and water flow parameters obtained in step 1, determine the bedload transport width B' (i.e., the lateral range of bedload movement within the cross section), and conduct more frequent sampling within the transport zone to verify and avoid missed measurements;

[0223] The instantaneous sediment transport rate per unit width is calculated using the dimensionlessly consistent modified Szamov formula:

[0224] ;

[0225] In the formula: k2 is the bedload correction coefficient, which is calibrated by fitting measured sampling data, and is set to 1.0 in this embodiment; C0 is the Szamov empirical constant (dimensionless), which is determined by measured bedload sampling, and is set to 0.27 in this embodiment; ρ s The density of sediment (kg / m³) 3 ), Natural quartz sand is taken at 2650 kg / m³ 3 ;ρ w Water density (kg / m³)3 Freshwater intake: 1000 kg / m³ 3 The seawater velocity is determined by referring to tables based on temperature and salinity. U(y) is the average cross-sectional velocity at this horizontal coordinate. c 'The initial flow velocity of the sediment is calculated based on the sediment particle size d and the water depth h(y);

[0226] Starting flow rate U c 'The following is obtained through explicit calculation using the critical Shields number combined with the logarithmic velocity distribution law:'

[0227] ;

[0228] In the formula k s =2.5d is the Nikuradse equivalent roughness height, and e=2.718 is the natural constant base.

[0229] Instantaneous bedload transport rate at the composite cross section: Instantaneous bedload transport rate g per unit width b (y,t) is integrated laterally over the bedload transport width B' to obtain the instantaneous bedload transport rate Q at the cross section. sb (t):

[0230] ;

[0231] Where dy is the differential element along the cross-sectional direction (lateral direction) of the river;

[0232] Calculate the total bedload flux over a given period: This is based on the instantaneous bedload transport rate Q at the cross section. sb (t) is integrated over time to obtain the total bedload flux S during time interval T. sb :

[0233] ;

[0234] Collaborative correction: Introducing a spatial variation exchange coefficient k3(y) based on the corrected Rouse number. i ,t), to achieve bidirectional conservation correction of suspended mass and bedload:

[0235] ;

[0236] In the formula: η is the exchange strength coefficient (dimensionless), which is calibrated by actual measured suspension-thrust ratio.

[0237] Mass conservation bidirectional correction is adopted:

[0238] ;

[0239] ;

[0240] Where, q sb,i(t) represents the instantaneous sediment transport rate per unit width at time t at the location of the i-th sub-section;

[0241] Corrected instantaneous suspended sediment transport rate of cross section and the corrected instantaneous bedload transport rate satisfy:

[0242] ;

[0243] The total flux of the sand remains constant, strictly satisfying the law of conservation of mass.

[0244] Step 5, total sand flux synthesis and accuracy verification, specifically includes:

[0245] Synthetic total sediment flux: Instantaneous sediment transport rate of the entire cross section The total flux S of the entire sand during time period T t =S s +S sb ;

[0246] Accuracy verification: The calculation results are verified by comparing measured values ​​with error analysis. A portion of the velocity measurement verticals are selected, and the suspended sediment and bedload transport rates are measured by direct sampling. The results are compared with those calculated by this method to calculate the relative error. If the relative error is greater than 5%, the correction coefficients k1, k2, and k3 are recalibrated until the error meets the requirements (relative error ≤ 5%).

[0247] Flux mechanism decomposition: For tidal zones, the DYER flux mechanism decomposition method is adopted to decompose the total sediment flux into the contributions of different sediment transport mechanisms such as horizontal flux and tidal pump flux, quantifying the proportion and contribution of each sediment transport item during the tidal cycle change process, and providing support for the analysis of sediment transport mechanism.

[0248] Step 6: Output the calculation results. Organize the parameters, correction coefficients and calculation results in the calculation process. Output the instantaneous suspended sediment transport rate curve, the instantaneous bedload transport rate curve and the instantaneous total sediment transport rate curve of the target section, as well as the total suspended sediment flux, total bedload flux and total total sediment flux within the time period T. At the same time, output the accuracy verification report, clarify the error range and correction basis, and provide a reference for practical applications.

[0249] In this embodiment, in step 1, the number of velocity measuring vertical lines is determined according to the cross-sectional width: when the cross-sectional width is ≤50m, 5 to 8 vertical lines are arranged; when the cross-sectional width is >50m and ≤100m, 8 to 12 vertical lines are arranged; when the cross-sectional width is >100m, 12 to 20 vertical lines are arranged, and the arrangement is denser in areas where the flow velocity and water depth change abruptly to ensure the representativeness of the parameter collection.

[0250] In this embodiment, in step 2, the correction coefficient of the modified Rouse sediment concentration distribution formula is obtained by fitting the measured sediment concentration data using the least squares method, and the goodness of fit R is... 2 ≥0.95, to ensure consistency between the interpolation curve and the measured data;

[0251] In this embodiment, in step 4, the initial flow velocity of the sediment is U c The revised formula is used to calculate the accuracy of the calculation under different sediment types and different flow conditions by incorporating parameters such as sediment unit weight and water viscosity.

[0252] In this embodiment, for scenarios with data shortages, the single-sand-fractured-sand relationship method can be used as an alternative to the main solution. The following process achieves interface compatibility with the spatial interpolation in step 2:

[0253] (1) Establishing a single-sand-sedimentary relationship model: Based on historical measured data, a single-sample sediment concentration C model was established. s Compared with the average sand content of the cross section The regression relationship, for example (a' is the regression coefficient, b is the regression constant), or a power function / exponential function model, with a goodness-of-fit R². 2 ≥0.9;

[0254] (2) Estimate the average sediment content of the cross section: Measure the sediment content C of each sample on site. s Substituting into the above model, we obtain the average sediment concentration of the cross section. ;

[0255] (3) Vertical-horizontal distribution to generate c(y,z,t):

[0256] Vertical distribution: A modified Rouse sediment concentration distribution model is adopted to... The formula for assigning the vertical water depth position to each vertical line is:

[0257] ;

[0258] Where c a (y,t) is derived from the average sediment content of the cross section. Constraints determined;

[0259] Lateral distribution: Using the first boundary cubic spline function from step 2, the vertical average sediment concentration of each vertical line is interpolated laterally to generate a continuous sediment concentration distribution field for the entire cross section.

[0260] (4) Access the main scheme process: The allocated c(y,z,t) can be directly input into the vertical / horizontal interpolation process in step 2, and the subsequent calculation is consistent with the main scheme.

[0261] In another embodiment of this application, a cross-section in the middle reaches of a natural river is used as the target. This cross-section has a water surface width of 80m, a water depth of 2-6m, and the sediment is mainly medium-fine sand (particle size 0.02-0.1mm). There is no tidal influence. The method of this invention is used to calculate the sediment flux of the cross-section during the time period T=24h. The specific steps are as follows:

[0262] Step 1: Obtain the basic parameters and measured data of the cross-section.

[0263] Basic topographic parameters: The transverse coordinates y (0~80m) and corresponding water depth h (y) of the cross section were obtained by actual measurement with a depth sounder. The water depth distribution is as follows: h=2m at the shore and h=6m at the center of the cross section, showing a symmetrical distribution.

[0264] Flow parameters: Ten velocity measuring vertical lines (lateral coordinates y=0, 10, 20, 30, 40, 50, 60, 70, 80 m) were arranged along the cross-section. The instantaneous flow velocity u(y,z,t) at different relative water depths (0.2, 0.4, 0.6, 0.8) along each vertical line was measured using a Doppler current meter. The measured instantaneous flow rate Q(t) of the cross-section ranged from 120 to 150 m³ / h. 3 / s;

[0265] Sediment parameters: Samples were taken simultaneously along each velocity measuring vertical line, and the instantaneous sediment concentration c(y,z,t) at different relative water depths was measured, ranging from 0.05 to 0.2 kg / m³. 3 The particle size of sediment is d=0.03~0.08mm, and the particle size threshold for suspended and bedload sediment is determined to be 0.05mm.

[0266] Environmental parameters: This section is a natural river with no tidal influence, so there is no need to measure temperature and salinity. Only the water viscosity is measured for calibration correction coefficients.

[0267] Step 2: Perform optimized calculations of cross-sectional division and parameter interpolation.

[0268] Section division: Based on 10 velocity measuring vertical lines, the section is divided into 9 sub-sections, each with a transverse width Δy. i =10m;

[0269] Vertical parameter interpolation: Logarithmic function interpolation was used to interpolate the flow velocity and sediment concentration along each vertical line. The goodness of fit R of the corrected Rouse sediment concentration distribution formula was determined. 2 =0.96, ensuring the accuracy of the vertical distribution curve;

[0270] Lateral parameter interpolation: The cubic spline function of the first boundary is used to perform lateral interpolation on the vertical average flow velocity and vertical average sediment concentration of each vertical line, so as to obtain the continuous distribution field of flow velocity and sediment concentration of the entire cross section, thus eliminating the parameter abrupt change caused by excessive vertical spacing.

[0271] Step 3: Calculate the suspended sediment flux.

[0272] Calculate the instantaneous suspended sediment transport rate per unit width: The suspended sediment correction coefficient k1 is calibrated based on measured data and taken as 1.02. Substitute this value into the formula to calculate the instantaneous suspended sediment transport rate q per unit width for each vertical line. si (y,t);

[0273] Calculate the instantaneous suspended sediment transport rate of each sub-section: the instantaneous suspended sediment transport rate q of each sub-section. si (t)=q si (y,t)×10m;

[0274] Instantaneous suspended sediment transport rate at the composite cross-section: The instantaneous suspended sediment transport rate Q at the cross-section is obtained by summing. s (t), ranging from 6.0 to 7.5 kg / s;

[0275] Calculate the total flux of suspended matter over time: Use the flow-weighted method to calculate Q. s (t) is integrated over time to obtain the total suspended mass flux S over 24 hours. s =622.08t.

[0276] Step 4: Calculate bedload flux.

[0277] Determine the bedload transport zone: Based on sediment particle size and flow parameters, determine the bedload transport width B' = 60m (lateral coordinate 10~70m);

[0278] Calculate the instantaneous bedload transport rate per unit width: The bedload correction factor k2 is calibrated to 0.98. Substitute this into the corrected Shamov formula to calculate the instantaneous bedload transport rate g per unit width at each lateral coordinate. b (y,t);

[0279] Instantaneous bedload transport rate at the composite cross-section: The instantaneous bedload transport rate Q at the cross-section is obtained by integrating over the transport width B'. sb (t), ranging from 0.3 to 0.45 kg / s;

[0280] Calculate the total bedload flux over a 24-hour period: Integrate over time to obtain the total bedload flux S. sb =30.24t;

[0281] Synergistic correction: The suspended-bedload conversion coefficient k3 is calibrated to 0.02, the suspended-bedload exchange flux is 0.02 × 30.24 = 0.60t, the corrected total suspended load flux is 622.08 + 0.60 = 622.68t, and the corrected total bedload flux is 30.24 - 0.60 = 29.64t. The total amount of sand before and after correction is 652.32t, satisfying the law of conservation of mass.

[0282] Step 5: Synthesis and accuracy verification of total sand flux.

[0283] Synthetic total sand flux: Total sand flux S within 24 hours t =622.68 + 29.64 = 652.32t;

[0284] Accuracy verification: In this embodiment, three velocity measurement vertical lines (y=20, 40, 60m) were selected, and the suspended sediment and bedload transport rates were measured by direct sampling method. The results were compared with those calculated by this method, and the relative error of the calculation was ≤5%, which meets the accuracy requirements.

[0285] Step 6: Output the calculation results.

[0286] Output the instantaneous suspended sediment transport rate curve (range 6.0~7.5 kg / s), the instantaneous bedload transport rate curve (range 0.3~0.45 kg / s), and the instantaneous total sediment transport rate curve (range 6.3~7.95 kg / s) for the cross section over 24 hours, as well as the corrected total suspended sediment flux of 622.68 t, the corrected total bedload flux of 29.64 t, and the total total sediment flux of 652.32 t. At the same time, output the accuracy verification report, specifying the correction coefficients and error range.

[0287] According to one aspect of this application, in other scenarios, taking a river estuary section as the target, this section is affected by both runoff and tides, with a water surface width of 120m, a water depth of 3-8m, and sediment mainly consisting of fine sand and cohesive sediment (particle size 0.005-0.06mm), a temperature of T=15-20℃, and a salinity of S=10-25‰. The method of this invention is used to calculate the net sediment flux of the section with a tidal period of T=12h. The specific steps are as follows:

[0288] Step 1: Obtain the basic parameters and measured data of the cross-section.

[0289] Basic topographic parameters: The transverse coordinate y (0~120m) and corresponding water depth h (y) of the cross section were measured by a depth sounder. The water depth varies with the tide level from 3 to 8m.

[0290] Water flow parameters: Fifteen velocity measuring verticals were arranged along the cross-section. The instantaneous flow velocity u(y,z,t) at different relative water depths along each vertical was measured using a Doppler current meter. The instantaneous flow rate Q(t) of the cross-section was measured simultaneously (positive during high tide and negative during low tide).

[0291] Sediment parameters: Instantaneous sediment concentration c(y,z,t) at different relative water depths along each vertical line, ranging from 0.1 to 0.3 kg / m³. 3 The particle size of sediment is d=0.005~0.06mm, and the particle size threshold for suspended and bedload sediment is 0.05mm.

[0292] Environmental parameters: seawater temperature T and salinity S at different time points of the measured cross-section were used to correct for the influence of sediment flocculation on sediment content.

[0293] Step 2: Perform optimized calculations of cross-sectional division and parameter interpolation.

[0294] Section division: The cross section is divided into 14 sub-sections, each with a transverse width Δy. i =8.57m (excluding the two end sections), adapting to changes in cross-sectional topography;

[0295] Vertical parameter interpolation: Logarithmic function interpolation was used to vertically interpolate the flow velocity and sediment concentration. The goodness of fit R of the corrected Rouse sediment concentration distribution formula was determined. 2 =0.97;

[0296] Lateral parameter interpolation: Lateral interpolation is performed using the first boundary cubic spline function to eliminate the error caused by uneven parameter distribution due to tides.

[0297] Step 3: Calculate the suspended sediment flux.

[0298] Calculate the instantaneous suspended sediment transport rate per unit width: The suspended sediment correction coefficient k1 is obtained by fitting temperature T and salinity S, with a value range of 1.03~1.08, to correct the sediment content deviation caused by flocculation.

[0299] Calculate the instantaneous suspended sediment transport rate of the sub-section and the section: Calculate the instantaneous suspended sediment transport rate Q of the section using the method described above. s (t) (positive during high tide, negative during low tide);

[0300] Calculate the net flux of suspended mass during the tidal cycle: for Q s (t) is integrated over the tidal period to obtain the net suspended mass flux S. s =185.2t (positive, indicating sediment transport to the sea).

[0301] Step 4: Calculate bedload flux.

[0302] Determine the bedload transport zone: Bedload transport width B' = 90m, dynamically adjusted according to tidal level changes;

[0303] Calculate the instantaneous sediment transport rate per unit width: The sediment transport correction factor k2 is calibrated to 1.05 and substituted into the corrected Shamov formula for calculation;

[0304] Synthesis and time integration of instantaneous bedload transport rate at cross-sections: yielding the net bedload tidal flux S during the tidal cycle. sb =9.8t (positive);

[0305] Synergistic correction: The suspended-bedmass conversion coefficient k3 is calibrated to 0.03, the suspended-bedmass exchange rate is 0.03 × 9.8 = 0.29t, the corrected net suspended mass flux is 185.2 + 0.29 = 185.49t, and the corrected net bedmass flux is 9.8 - 0.29 = 9.51t. The total net flux of sand before and after correction is 195.0t, satisfying the law of conservation of mass.

[0306] Step 5: Synthesis and accuracy verification of total sand flux.

[0307] Synthetic total sand flux: Net flux S throughout the entire sand tide cycle t =185.49+9.51=195.0t (positive direction).

[0308] Flux Mechanism Decomposition: The net sediment flux was decomposed using the DYER flux mechanism to obtain the advection flux contribution term and the tidal pump flux contribution term. The decomposition results show that sediment transport during this period was mainly driven by advection, with the tidal pump effect providing an additional contribution of about 10% to 15%. The sum of the terms of different sediment transport mechanisms equals the net sediment flux, satisfying the completeness requirement of the decomposition.

[0309] Accuracy verification: In this embodiment, the measured relative error is 4.1%, which meets the accuracy requirements.

[0310] Step 6: Output the calculation results.

[0311] Output the instantaneous sediment transport rate curves of suspended sediment, bedload, and total sediment during the tidal cycle of this section, as well as the corrected net flux during the tidal cycle (suspended sediment 185.49t, bedload 9.51t, total sediment 195.0t). At the same time, output the flux mechanism decomposition results and accuracy verification report to provide accurate data support for the analysis of sediment transport in the estuary.

[0312] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A method for calculating cross-sectional sediment flux, characterized in that, include: Acquire basic data for the target cross section, including topographic parameters, water flow parameters, sediment parameters, and environmental parameters; Based on the basic data, parameter space interpolation is performed to construct a continuous distribution field of cross-sectional flow velocity and a continuous distribution field of cross-sectional sediment concentration. Based on the continuous distribution field of cross-sectional velocity, the continuous distribution field of cross-sectional sediment concentration, and environmental parameters, the suspended sediment transport parameters of the cross-section are calculated. Based on the basic data, calculate the bedload transport parameters of the cross section; Based on the mass conservation principle, the cross-sectional suspended sediment transport parameters and cross-sectional bedload transport parameters are simultaneously corrected in two directions using the exchange coefficient that varies with space, so as to obtain the corrected cross-sectional suspended sediment transport parameters and corrected cross-sectional bedload transport parameters. Based on the corrected suspended sediment transport parameters and the corrected bedload transport parameters of the cross section, the total sediment flux of the target cross section is synthesized and output.

2. The method according to claim 1, characterized in that, The vertical interpolation process for constructing a continuous distribution field of sediment content in a cross section includes: The reference elevation is determined based on the sediment particle size and the water depth in the topographic parameters. Obtain the sand content at the reference elevation; A sediment concentration distribution model based on flocculation effective settling velocity correction was adopted, and the sediment concentration at the reference elevation and the corrected Rouse number were combined to calculate the sediment concentration distribution at each vertical depth of the target section.

3. The method according to claim 1, characterized in that, The transverse interpolation process for constructing the continuous distribution field of cross-sectional velocity and the continuous distribution field of cross-sectional sediment concentration includes: Obtain the vertical average parameters corresponding to each velocity measuring line; The vertical average parameters are fitted laterally using the first boundary cubic spline function; In the fitting process, the spline function is forced to satisfy the third derivative continuity at the second node and the penultimate node near both ends of the cross section by using the non-node end condition, so as to obtain the continuous distribution field of the entire cross section.

4. The method according to claim 1, characterized in that, Calculate the suspended sediment transport parameters of the cross-section, including: Spatial integration of the continuous distribution field of cross-sectional velocity and the continuous distribution field of cross-sectional sediment concentration yields the basic suspended sediment transport rate. Based on the environmental parameters of temperature and salinity, the environmental correction coefficient is calculated using a preset environmental coupling correction function. The suspended sediment transport parameters of the cross section are obtained by weighting the basic suspended sediment transport rate using environmental correction coefficients.

5. The method according to claim 1, characterized in that, Calculate the bedload transport parameters of the cross section, including: Obtain the cross-sectional average flow velocity of the target section at each lateral coordinate. The density difference term is calculated based on the sediment density in the sediment parameter and the water density in the environmental parameter. The instantaneous bedload transport rate per unit width at each lateral coordinate is obtained by multiplying the density difference term, the sediment particle size in the sediment parameters, the difference between the cross-sectional average flow velocity and the sediment initiation velocity, the ratio of the cross-sectional average flow velocity to the sediment initiation velocity, and the ratio of the sediment particle size to the water depth in the topographic parameters.

6. The method according to claim 5, characterized in that, The initial flow velocity of sediment is determined in the following way: The equivalent roughness height is determined based on the particle size of the sediment. A logarithmic calculation term is constructed using the equivalent roughness height and water depth; By combining logarithmic calculation terms with explicit calculations, the sediment initiation velocity corresponding to different water depths is obtained.

7. The method according to claim 1, characterized in that, The exchange coefficient is used to perform bidirectional synchronous correction of the suspended sediment transport parameters and the bedload transport parameters of the cross section, including: Calculate the suspended exchange amount based on the exchange coefficient and cross-sectional bedload transport parameters; The suspended sediment transport parameters of the cross section are added to the suspended exchange rate to obtain the corrected suspended sediment transport parameters of the cross section. Subtracting the suspended exchange rate from the cross-sectional bedload transport parameters yields the corrected cross-sectional bedload transport parameters. Among them, the sum of the corrected cross-sectional suspended sediment transport parameters and the corrected cross-sectional bedload transport parameters is equal to the sum of the parameters of the two before the correction.

8. The method according to claim 1, characterized in that, When the target section is located in a tidal-controlled region, after outputting the total sand flux of the section, it also includes: The total sediment flux at the cross section was decomposed using the flux mechanism decomposition method to obtain the horizontal flux contribution term and the tidal pump flux contribution term, so as to quantify the contribution ratio of different sediment transport mechanisms to the total flux.

9. The method according to claim 5, characterized in that, When calculating the density difference term, the water density is determined in real time based on environmental parameters such as temperature and salinity, using a preset density lookup table or fitting function.

10. The method according to claim 1, characterized in that, The threshold for sediment particle size is a dynamically determined, non-fixed value; Specifically, based on the measured water flow intensity and sediment settling characteristics, the particle size boundary between suspended and bedloaded sediments under the current operating conditions is dynamically identified.

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