A method for evaluating and predicting the accuracy effect of tidal flat-tidal creek

Abstract

The application discloses a kind of tidal flat-tidal ditch precision effect evaluation prediction method, first selected research area, according to the physical parameter of research area to determine grid scale, boundary condition and dynamic parameter, based on Delft3D hydrodynamic-sediment coupling model, combined with parameterization scheme and structured processing, by constructing the numerical model of different grid resolution simulates tidal flat geomorphology evolution situation, using structured processing procedure realizes the automation extraction and analysis of tidal ditch topographic feature, output each level total length and branch number, and through color coding visualization tidal ditch spatial distribution characteristics;To effectively evaluate the simulation precision and stability of complex hydrodynamic process tidal flat-tidal ditch, reveal the influence law of different grid resolution on tidal ditch development location, plane morphological characteristics and sediment dynamics process, and propose grid configuration strategy based on error propagation constraint;For estuary and coast comprehensive management, ecological restoration and water resources management provide scientific basis and technical support.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computational fluid dynamics and estuarine dynamics, in particular to a tidal flat-tidal creek precision effect evaluation and prediction method. BACKGROUND

[0002] Tidal creek refers to the trench formed between the coastline and the ocean under the action of tides, which usually occurs in estuaries, tidal flats and other areas. The formation of tidal creek is due to the complex interaction between hydrodynamic force, sediment transport and biological process. These interactions drive the balanced evolution of the tidal flat-tidal creek topography. The tidal flat-tidal creek system is a key zone of sea-land interaction, which has important ecological function and economic value.

[0003] Although great progress has been made in tidal flat evolution in recent years, the development of tidal creek has always been a difficult problem in research. In recent years, with the development of marine science and ecology, the study of tidal creek has gradually deepened, but little is known about the influence of grid scale on the development of tidal creek. In recent years, two-dimensional shallow water models have gradually attracted attention because they can analyze tidal creek. Although two-dimensional shallow water models can theoretically provide more detailed information about tidal creek generation, including the length of the tidal creek, the spatial distribution of flow velocity, and sediment transport, in practical operation, the choice of grid scale often becomes the main obstacle to its widespread application. Grids are used to subdivide the entire calculation area. The grid scale not only concerns the calculation efficiency, but also directly affects the accuracy and physical reality of the simulation results, so finding a suitable grid scale is crucial for tidal creek simulation.

[0004] Currently, the industry is generally faced with a problem that when facing a specific research area, how to choose a grid resolution to most accurately simulate the tidal creek under the premise of controllable cost. Too low resolution will cause secondary small tidal creek to be ignored, and the accuracy is insufficient; too high resolution will have large simulation cost, low processing efficiency, and may introduce too many unnecessary details. The tidal flat topography is complex and variable, and how to accurately capture the topographic details and consider the calculation efficiency is a difficult problem in numerical simulation. Different grid sizes have different effects on the treatment of topographic complexity, and how to choose a suitable grid resolution to accurately simulate the topographic complexity is a problem to be solved.

[0005] Therefore, there is an urgent need in the art for an evaluation and prediction method that can predict the precision effect before numerical simulation and provide a scientific basis for optimal resolution selection. SUMMARY

[0006] To solve the above technical problems, the present application provides a tidal flat-tidal creek precision effect evaluation and prediction method, comprising the following steps:

[0007] S1, select a target tidal flat-tidal creek system as a research area, collect physical parameters of the area, including topography, water depth, tidal level, flow velocity, flow direction, sediment concentration and bottom type; and based on the collected physical parameters, determine the dynamic parameters of numerical simulation, including boundary conditions, bottom friction coefficient and sediment parameters;

[0008] S2, based on the parameters determined in the previous step, a Delft3D modeling system is used to build a hydrodynamic-sediment coupling model, which includes a cluster of numerical models with different grid resolutions, all models have the same physical parameters, initial conditions and boundary conditions except for grid resolution, so that the difference in simulation results is only caused by the change of grid resolution;

[0009] S3, run the built hydrodynamic-sediment coupling model cluster with multiple sets of different grid resolutions to simulate the dynamic evolution process of the tidal flat topography for a specified time; after the simulation is completed, the underwater digital elevation model data of each model at the final time is output;

[0010] S4, automatically calculate and output a set of tidal creek shape and dynamic characteristic parameters, including the total length, branch number and tidal creek density of each level tidal creek; and superimpose the extracted tidal creek edge polygon, center line skeleton and watershed distribution on the original topography for multi-dimensional visual expression;

[0011] S5, compare the simulation results of each resolution grid model with the simulation results of the highest resolution grid model to evaluate the influence of different grid resolutions on the spatial distribution characteristics of the tidal creek, the planar shape characteristics of the tidal creek, the sedimentation dynamics process and the numerical stability of the model;

[0012] S6, based on the quantitative evaluation results, a grid configuration strategy based on error constraint is proposed; a comprehensive evaluation report is generated, which includes comparison charts of simulation results of different resolutions, quantitative evaluation table of precision and recommended grid configuration strategy.

[0013] The further defined technical solution of the application is:

[0014] Further, in step S1, the length and width of the research area are both 5km, the hydrodynamic-sediment coupling model is only set to the right side as an open boundary, the boundary condition is set to S2 tidal, the period is 12h, the amplitude is 0.6m, and the average sea level elevation is 0m.

[0015] As the tidal flat-tidal creek precision effect evaluation prediction method described above, in step S1, the roughness along the path in the hydrodynamic-sediment coupling model is uniformly taken as a constant, the Manning coefficient is adopted, and the values of U direction and V direction are both 0.015.

[0016] The method for evaluating and predicting the precision effect of a tidal flat-tidal creek, as described above, in step S2, the water-sediment coupling model comprises a water flow module and a sediment module, the water flow module solves the Navier-Stokes equation of an incompressible fluid based on the Boussinesq approximation and the static pressure assumption, and the continuity equation is as follows:

[0017] ;

[0018] The momentum conservation equation is as follows:

[0019] ;

[0020] ;

[0021] wherein x and y represent Cartesian coordinates, u and v represent the vertical line average flow velocities in the x and y directions respectively, t represents time; h represents water depth, η represents water level relative to a certain datum, f represents the Coriolis parameter, v represents the horizontal eddy viscosity coefficient, C f represents the friction coefficient.

[0022] The method for evaluating and predicting the precision effect of a tidal flat-tidal creek, as described above, the sediment module transports viscous sand and non-viscous sand, the transportation of the viscous sand is calculated according to the suspended sediment, and the erosion and deposition of the viscous sand are described by a convection-diffusion equation with source and sink terms:

[0023] ;

[0024] wherein c represents the vertical average concentration of sediment; Q mud,e and Q mud,d represent the erosion amount and the deposition amount respectively.

[0025] The method for evaluating and predicting the precision effect of a tidal flat-tidal creek, as described above, the erosion amount and the deposition amount are calculated using the following Patheniades-Krone formula:

[0026] ;

[0027] ;

[0028] wherein M e represents the erosion coefficient; represents the critical incipient shear stress of sediment; represents the sediment settling velocity; represents the sediment settling shear stress.

[0029] A method for predicting the effect of a tidal flat-tidal creek accuracy evaluation as described above, the transport of non-cohesive sand is calculated in combination of suspended load and bed load. In a one-dimensional model, the transport of non-cohesive sand is simulated using Soulsby-van Rijn transport formula, and the transport amount is described by the following formula:

[0030] ;

[0031] ;

[0032] ;

[0033] ;

[0034] wherein A sb represents a bed sand load coefficient; A ss represents a suspended sand load coefficient; A cal represents a calibration coefficient; C D represents a resistance coefficient generated only by tidal flow; represents a median particle size of the sediment; and g represents a gravitational acceleration; , represents the root mean square of the wave point orbit flow velocity; U cr represents a threshold value of the flow velocity, which depends on the median particle size of the sediment and the river bed slope; represents the relative density of the sediment, represents the density of the sediment, represents the density of water; represents a dimensionless particle size.

[0035] A method for predicting the effect of a tidal flat-tidal creek accuracy evaluation as described above, in a two-dimensional model, the sediment formula is simulated using the Engelund and Hansen total sand transport formula:

[0036] ;

[0037] wherein, represents the total sediment transport rate, represents the flow velocity, D 50 represents the median particle size, and C represents the resistance coefficient.

[0038] A method for predicting the effect of a tidal flat-tidal creek accuracy evaluation as described above, in the sediment formula, the size of the sediment flux is modified according to Bagnold's formula:

[0039] ;

[0040] ;

[0041] wherein, Indicates the correction parameter; This indicates the corrected sediment flux; Indicates a dimensionless coefficient; the default value is 1. This represents the internal friction angle of the bed sediments, with a default value of 30°. Indicates the longitudinal slope, where Indicates the difference in elevation of the bottom slope. Indicates horizontal distance.

[0042] As described above, in the method for evaluating and predicting the accuracy of tidal flat-channel analysis, an orthogonal sediment flux is introduced into the sediment formula to adjust the sediment flux. Direction:

[0043] ;

[0044] Among them, S n The magnitude is the orthogonal sediment flux, and the direction is downward sloping; Indicates a dimensionless coefficient; the default value is 1.5. Indicates the lateral slope, which is orthogonal to the streamline direction;

[0045] Therefore, sediment flux for:

[0046] ;

[0047] in, Indicates total sediment flux; This represents orthogonal sediment flux.

[0048] The beneficial effects of this invention are:

[0049] (1) In this invention, the entire process of extracting topographic data into morphological parameters is automated based on Python scripts, which avoids the subjectivity of manual interpretation and has the advantages of high efficiency and repeatability; it integrates computational geometry methods and hydrological methods to accurately characterize the overall structure of tidal channels;

[0050] (2) In this invention, the results of different grid resolutions obtained by the Delft3D hydrodynamic-sediment coupling model are compared and analyzed by the tidal channel visualization system, and a numerical simulation evaluation system suitable for the accuracy problem of tidal flat landform simulation is constructed, which provides a scientific basis for the evaluation and prediction method for the optimal resolution selection of tidal flat-tidal channel grid simulation.

[0051] (3) In the present application, by constructing different grid resolution simulation groups, the system analyzes the influence of water power simulation grid resolution on tidal flat-tidal ditch landform, so as to reveal the change law of tidal ditch length, tidal ditch density and spatial distribution of tidal ditch under different grid resolutions, and provide theoretical support for optimizing grid resolution configuration strategy.

[0052] (4) In the present application, the dynamic process of tidal ditch development, morphological evolution and dynamic response can be accurately captured under the condition of reasonable control of computing resources, which is suitable for tidal flat system simulation under large-scale and complex topographic conditions, and provides a system evaluation accuracy and prediction tool for tidal flat-tidal ditch geomorphological evolution mechanism research and engineering application. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 It is the overall flowchart of the present application;

[0054] Figure 2 It is the precision verification schematic diagram in the embodiment of the present application;

[0055] Figure 3 It is the bed surface elevation schematic diagram in the embodiment of the present application;

[0056] Figure 4 It is the tidal ditch visualization schematic diagram in the embodiment of the present application;

[0057] Figure 5 It is the hierarchical tidal ditch length comparison schematic diagram in the embodiment of the present application;

[0058] Figure 6 It is the tidal ditch relative error rate schematic diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0059] The tidal flat-tidal ditch precision effect evaluation and prediction method provided in the embodiment, as shown in Figure 1 The steps include:

[0060] S1, select the target tidal flat-tidal ditch system as the research area, collect the topography, water depth, tidal level, flow velocity, flow direction, sediment concentration and bottom type and other physical parameters of the area; and based on the collected physical parameters, determine the boundary conditions, bottom friction coefficient and sediment parameters and other dynamic parameters of numerical simulation. The selection of grid size needs to meet the generation of tidal ditch and the stability of numerical model, and reasonable boundary conditions need to be set to meet the physical reality.

[0061] The length and width of the study area are both 5 km. The hydrodynamic-sediment coupling model is only set on the right side as an open boundary. The boundary condition is set as semi-diurnal tide (S2 component), with a period of 12 h, an amplitude of 0.6 m, and a MSL (Mean Sea Level) of 0 m. The Manning coefficient is used in the model, and the uniform constant is taken as 0.015 in the U direction and the V direction.

[0062] S2, based on the parameters determined in step S1, a hydrodynamic-sediment coupling model is constructed using the Delft3D modeling system. The model includes a cluster of numerical models with different grid resolutions. All models have consistent physical parameters, initial conditions, and boundary conditions except for the grid resolution, so that the differences in simulation results are only due to the change in grid resolution. By constructing a cluster of numerical models with different grid resolutions and keeping all other parameters consistent, a comparative experiment of control variables is constructed, which ensures that the differences in subsequent evaluation results are due to the grid scale effect, rather than other interference factors, making the conclusion more scientific and rigorous.

[0063] The Flow module of Delft3D solves the N-S equation (Navier-Stokes equation) of incompressible fluid based on the Boussinesq approximation and the static pressure assumption. The continuity equation is as follows:

[0064] ;

[0065] The momentum conservation equation is as follows:

[0066] ;

[0067] ;

[0068] Where x and y represent Cartesian coordinates, u and v represent the vertical average flow velocities in the x and y directions, respectively, and t represents time. h represents water depth, η represents water level relative to a certain reference, f represents the Coriolis parameter, v represents the horizontal eddy viscosity coefficient, and C f represents the friction coefficient.

[0069] The hydrodynamic-sediment coupling model also includes a sediment module, which has an intermediary role connecting the hydrodynamic module and the geomorphological evolution module. Sediment transport is usually divided into bed load and suspended load and discussed separately. Bed load moves near the bed surface and is immediately affected by the terrain. Bed load particles move near the bed surface in a rolling, sliding, or saltation manner, such as gravel rolling along the riverbed in mountainous rivers. Suspended load is supported by turbulent diffusion of the flow and suspended in the water for a long time, such as the large amount of suspended silt and clay in the Yellow River, which makes the water turbid.

[0070] For cohesive sediment, the erosion and deposition are described by the advection-diffusion equation with source and sink terms:

[0071]

[0072] where c is the vertical average concentration of sediment; Q mud,e and Q mud,d are the erosion and deposition rates, respectively.

[0073] The erosion and deposition rates are usually calculated using the following Patheniades-Krone formula:

[0074]

[0075]

[0076] where M e is the erosion coefficient (kg / m 2 / s); is the critical incipient shear stress of sediment (Pa); is the settling velocity of sediment (m / s 2 ); is the settling shear stress of sediment (Pa).

[0077] For non-cohesive sediment, the combined calculation of suspended load and bed load is required. In one-dimensional models, the transport of non-cohesive sediment is simulated using the Soulsby-van Rijn transport formula, which describes the transport rate as follows:

[0078]

[0079]

[0080]

[0081]

[0082] where A sb is the bed load coefficient; A ss is the suspended load coefficient; A cal is the calibration coefficient; C D is the drag coefficient due to tidal current only; is the median particle size of sediment; g is the acceleration due to gravity; , is the root mean square of the orbital velocity of wave mass points; U cr is the threshold value of flow velocity (m / s), which depends on the median particle size of sediment and the bed slope; ​​​​​​​represents the relative density of the sediment, where the density of the sediment , the density of water ; represents the dimensionless grain size.

[0083] In the two-dimensional model, to generate the tidal creek as soon as possible and explore the effect of consolidation on the tidal creek evolution, the sediment formula is simulated using Engelund and Hansen's total sediment transport formula:

[0084] ;

[0085] where, represents the total sediment transport rate (m 2 / s), represents the flow velocity (m / s), D 50 represents the median grain size, and C represents the resistance coefficient.

[0086] Considering the effect of the bottom slope, the size of the sediment flux is corrected according to Bagnold's formula:

[0087] ;

[0088] ;

[0089] where, represents the correction parameter; represents the sediment flux to be corrected (m 2 / s); represents the dimensionless coefficient, and the default value is 1; represents the internal friction angle of the bed sediment, and the default value is 30°; represents the longitudinal bottom slope, where represents the elevation difference of the bottom slope, represents the horizontal distance.

[0090] The direction of the sediment flux is further adjusted by introducing an orthogonal sediment flux to consider the transverse bottom slope:

[0091] ;

[0092] where, S n is the size of the orthogonal sediment flux (m 2 / s), and the direction is downward inclination; represents the dimensionless coefficient, and the default value is 1.5; represents the transverse slope, which is orthogonal to the flow direction.

[0093] Therefore, the sediment flux is:

[0094] ;

[0095] wherein, represents the total sediment flux; represents the orthogonal sediment flux.

[0096] S3, running the constructed water dynamics-sediment coupling model cluster of different grid resolutions, simulating the dynamic evolution process of the tidal flat topography for a set time length; after the simulation is completed, the underwater digital elevation model data of each model at the final time is output respectively.

[0097] By extracting the flow velocity after the tidal creek is completely formed and stable, and comparing and analyzing with the actual physical experiment data, the size and trend change are evaluated, so as to verify the precision of the model, as shown in Figure 2 , the average absolute error is 0.014 m / s after calculation, and the simulation result can show that the flow velocities of the five measuring points of the mathematical model constructed by the method of the embodiment are basically consistent with the flow velocities of the measuring points of the physical experiment, and the verification result is good.

[0098] S4, automatically calculating and outputting a set of comprehensive tidal creek morphology and dynamic characteristic parameters, including the total length, the number of branches and the density of the tidal creek of each grade; and superimposing the extracted tidal creek edge polygon, center line skeleton and watershed distribution on the original terrain to perform multi-dimensional visual expression, and intuitively displaying the spatial distribution characteristics and rules, realizing the transformation from complex geographic information to quantifiable indicators, and making the evaluation work from qualitative to quantitative. Combined with multi-dimensional visualization, the analysis efficiency of the result is greatly improved.

[0099] Since the topography of the tidal flat environment is relatively flat, the traditional watershed division method based on terrain gradient is invalid. The method of the embodiment adopts a virtual terrain method to accurately calculate the tidal creek area of each point along the center line skeleton: a virtual terrain surface is generated, data analysis is performed on the virtual terrain, and the tidal creek center skeleton line is accurately outlined.

[0100] The water dynamics-sediment coupling model constructed is used to simulate the sediment transport of the tidal flat in the research area, different groups are simulated in view of the change of the grid resolution, and the initial output result of the Delft3D model is as shown in Figure 3 , from which it can be roughly seen that the tidal flat elevation and the tidal creek contour. Then the terrain elevation data of the Delft3D result is input into the visualization process, and the spatial distribution characteristics of the tidal creek are intuitively displayed.

[0101] The hierarchical tidal creek length is visualized, as shown in Figure 4 , wherein the orange skeleton line represents the first grade tidal creek, the green skeleton line represents the second grade tidal creek, and the red skeleton line represents the third grade tidal creek; the visualization process extracts the skeleton of each grade tidal creek, and outputs the total length of each grade tidal creek, and finally displays as Figure 5The corresponding hierarchical gully length and number of bars are shown.

[0102] S5, comparing the simulation results of each resolution grid group with the simulation results of the model of the highest resolution grid, evaluating the influence of different grid resolutions on the spatial distribution characteristics of gullies, the planar morphological characteristics of gullies, the sediment dynamics process and the numerical stability of the model.

[0103] Under different grid resolutions, the simulation structure is visualized, and the spatial distribution characteristics of each group of gullies are compared and analyzed to reveal the variation characteristics of the spatial distribution of gullies at each level, such as Figure 4 As shown in the figure, the orange skeleton line represents the first-order gully, the green skeleton line represents the second-order gully, and the red skeleton line represents the third-order gully. It can be seen from the figure that the gully system presents a typical dendritic morphology in the plane, and has obvious hierarchical phenomenon. The distribution of gullies on the tidal flat is not uniform, and the gully density of each group is significantly different.

[0104] Under different grid resolutions, the obtained visualized gully result data is analyzed to compare the length and density variation characteristics of gullies at each level, such as Figure 5 As shown in the figure. It can be seen that the gully density under the 10m grid resolution is the largest, the total number of gullies is 40, and the total length of gullies is the longest, which is 50676.9m; the gully density under the 60m grid resolution is the smallest, the total number of gullies is 12, and the total length of gullies is the shortest, which is 27164.9m; among them, the gully density decreases the fastest between 10m-30m grid resolutions, with an average decrease of 26.25%, and the gully density and total length gradually stabilize after 30m. Specifically, the higher the grid resolution, that is, the smaller the simulation grid size, the greater the number of gully branches and the total length.

[0105] Under different grid resolutions, based on the 10m grid simulation results, the error of each group of gully length and the base group is calculated, and the error variation curve is drawn to reveal the advantages and disadvantages of gully simulation accuracy, such as Figure 6 As shown in the figure. The results show that the accuracy of the first-order and second-order gullies under the 20m grid is very high, and the error of the 10m grid accuracy is only 1.90% and 2.92%, the error of the first-order gully under the 30m grid is 4.37%, and the error of the second-order gully is 15.31%. The error of the main gullies of the 20m grid accuracy group is less than 5%, which meets the expectation and the error is within the acceptable range, indicating that the grid accuracy under this grid resolution is high and meets the requirements.

[0106] S6, based on the quantitative evaluation results, an error constraint-based grid configuration strategy is proposed; a comprehensive evaluation report is generated, which contains comparison charts of simulation effects of different resolutions, precision quantitative evaluation table and recommended grid configuration strategy, which is used to guide the comprehensive management planning, ecological restoration engineering design and water resource management decision of estuary and coastal areas, and provides scientific basis and technical support. By comparing the real tidal creek features extracted from the measured terrain data with the simulation results of different resolutions, the simulation results of the highest resolution grid and the simulation results of the low resolution grid, and by drawing the comparison chart of the length and density of each level of tidal creek from the visualization results of the tidal creek, the length and density of each level of tidal creek are obtained.

[0107] The method of the embodiment first selects a research area, determines the grid scale, boundary conditions and dynamic parameters according to the physical parameters of the research area, based on the Delft3D hydrodynamic-sediment coupling model, combines the parameterization scheme and the structured processing, simulates the tidal flat geomorphological evolution by constructing numerical models with different grid resolutions, realizes the automatic extraction and analysis of the tidal creek terrain features by using the structured processing flow, outputs the total length and the number of branches of each level, and visualizes the spatial distribution characteristics of the tidal creek by color coding.

[0108] The method of the embodiment can effectively evaluate the simulation accuracy and stability of the tidal flat-tidal creek of the complex hydrodynamic process, reveal the influence law of different grid resolutions on the development location, planar morphological characteristics and sediment dynamics process of the tidal creek, and propose a grid configuration strategy based on the error propagation constraint. It provides scientific basis and technical support for the comprehensive management, ecological restoration and water resource management of estuary and coastal areas.

[0109] In addition to the above embodiments, the present application can have other implementation manners. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A method for evaluating and predicting the accuracy of tidal flat-tidal channel effects, characterized in that: Includes the following steps: S1. Select the target tidal flat-tidal channel system as the study area, collect the physical parameters of the area, including topography, water depth, tidal level, flow velocity, flow direction, sediment content and bottom type; and based on the collected physical parameters, determine the dynamic parameters of the numerical simulation, including boundary conditions, bottom friction coefficient and sediment parameters. S2. Based on the parameters determined in the previous step, a hydrodynamic-sediment coupling model is constructed using the Delft3D modeling system. This model contains a cluster of numerical models with different grid resolutions. Except for the grid resolution, all physical parameters, initial conditions and boundary conditions of all models are kept consistent, so that the difference in simulation results is only due to the change in grid resolution. S3. Run the constructed cluster of multiple sets of hydrodynamic-sediment coupling models with different grid resolutions to simulate the dynamic evolution of tidal flat landforms over a set period of time. After the simulation is completed, the underwater digital elevation model data of each model at the final moment will be output. S4. Automatically calculate and output a set of tidal channel morphology and dynamic characteristic parameters, including the total length of tidal channels of each grade, the number of tributaries and the density of tidal channels; The extracted tidal channel edge polygons, centerline skeletons, and watershed distribution are then overlaid on the original terrain for multi-dimensional visualization. S5. Compare the simulation results of the models with each resolution grid with the simulation results of the model with the highest resolution grid to evaluate the impact of different grid resolutions on the spatial distribution characteristics of tidal channels, the planar morphological characteristics of tidal channels, the sedimentation dynamics process, and the numerical stability of the model. S6. Based on the quantitative evaluation results, a grid configuration strategy based on error constraints is proposed. Generate a comprehensive evaluation report, which includes comparison charts of simulation results at different resolutions, a quantitative accuracy evaluation table, and recommended grid configuration strategies.

2. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 1, characterized in that: In step S1, the length and width of the study area are both 5km. The hydrodynamic-sediment coupling model is set with only the right side as an open boundary. The boundary condition is set as S2 tidal constituent, with a period of 12h, an amplitude of 0.6m, and a mean sea level elevation of 0m.

3. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 2, characterized in that: In step S1, the friction roughness in the hydrodynamic-sediment coupling model is uniformly taken as a constant, using the Manning coefficient, with values ​​of 0.015 in both the U and V directions.

4. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 1, characterized in that: In step S2, the hydrodynamic-sediment coupling model includes a flow module and a sediment module. The flow module solves the Navier-Stokes equations for incompressible fluids based on the Boussinesq approximation and the static pressure assumption. The continuity equation is as follows: ； The equation for the conservation of momentum is as follows: ； ； Where x and y represent Cartesian coordinates, u and v represent the vertical average flow velocities in the x and y directions respectively, t represents time; h represents water depth, η represents water level relative to a certain reference, f represents the Coriolis parameter, v represents the horizontal eddy viscosity coefficient, and C f This represents the coefficient of friction.

5. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 4, characterized in that: The sediment module transports both cohesive and non-cohesive sand. The transport of cohesive sand is calculated as suspended sediment, and its scouring and deposition are described by a convection-diffusion equation including source and sink terms. ； Where c represents the vertical average concentration of sediment; Q mud,e and Q mud,d These represent the amount of scouring and the amount of sediment settling, respectively.

6. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 5, characterized in that: The scouring and sedimentation volumes are calculated using the following Patheniades-Krone formula: ； ； Among them, M e Indicates the erosion coefficient; This indicates the critical initiation shear stress of the sediment. Indicates the sediment settling velocity; This represents the shear stress caused by sediment settling.

7. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 5, characterized in that: The transport of non-cohesive sand is calculated as a combination of suspended and bedload. In the one-dimensional model, the transport of non-cohesive sand is simulated using the Soulsby-van Rijn transport formula, and its transport volume is described by the following formula: ； ； ； ； Among them, A sb Indicates the bed sand load factor; A ss Indicates the suspended sediment load factor; A cal Indicates the calibration factor; C D This represents the drag coefficient generated solely by tidal currents. Indicates the median particle size of sediment; g represents the acceleration due to gravity; , representing the root mean square velocity of the wave particle's orbit; U cr The threshold representing flow velocity depends on the median grain size of the sediment and the riverbed slope; This indicates the relative density of the sediment. Indicates the density of sediments, Indicates the density of water; This indicates the dimensionless particle size.

8. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 7, characterized in that: In the two-dimensional model, the sediment formula for the non-cohesive sand is simulated using Engelund and Hansen's total sediment transport formula: ； in, Indicates the total sediment transport rate. D represents the flow velocity. 50 The median particle size is represented by , and C represents the drag coefficient.

9. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 8, characterized in that: In the sediment formula, the magnitude of the sediment flux is modified according to Bagnold's formula as follows: ； ； in, Indicates the correction parameter; This indicates the corrected sediment flux; Indicates a dimensionless coefficient; the default value is 1. This represents the internal friction angle of the bed sediments, with a default value of 30°. Indicates the longitudinal slope, where Indicates the difference in elevation of the bottom slope. Indicates horizontal distance.

10. The method for evaluating and predicting the accuracy of tidal flat-tidal channel performance according to claim 9, characterized in that: In the sediment formula, an orthogonal sediment flux is introduced to adjust the sediment flux. Direction: ； Among them, S n The magnitude is the orthogonal sediment flux, and the direction is downward sloping. Indicates a dimensionless coefficient; the default value is 1.

5. Indicates the lateral slope, which is orthogonal to the streamline direction; Therefore, sediment flux for: ； in, Indicates total sediment flux; This represents orthogonal sediment flux.

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