Method and system for calculating wave dissipation effect of different gradient salt marsh vegetation under varying tidal level

Abstract

The application discloses a kind of calculation method and system of different gradient salt marsh vegetation wave-damping effect under varying tidal level.The method includes physical model test of wave incidence to salt marsh vegetation in tidal flat area, to obtain energy dissipation amount after wave through vegetation area and wave reflection amount in vegetation area;According to the arrangement specification of salt marsh vegetation in tidal flat area, energy dissipation amount and wave reflection amount, determine vegetation energy dissipation.The system includes input, calculation, calibration, output and the like module, for recording tidal level, height difference gradient and vegetation data, calculating wave energy attenuation rate, calibrating calculation model, to accurately calculate the wave-damping effect of salt marsh vegetation under different tidal level gradient.The calculation method and system proposed by the application have the characteristics of science, practicality, accuracy, efficiency and the like, and are suitable for port, coastal protection engineering, ecological restoration and coastal zone management and the like fields.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of coastal engineering and ecological environment protection, and particularly relates to a method and system for calculating the wave dissipation effect of salt marsh vegetation at different gradients under changing tidal levels. BACKGROUND

[0002] Currently, the protection and ecological restoration of tidal flat areas have become an important issue in coastal regions. In particular, in estuaries and coastal zones, tidal level changes and wave erosion have a serious impact on shoreline stability and ecological systems. Traditional hard structure protection methods, such as seawalls and retaining walls, while effective in resisting wave erosion, often damage the natural ecological environment, leading to a decrease in biodiversity and potentially causing other environmental problems. Therefore, there is an urgent need for a solution that can protect the shoreline while restoring and enhancing the ecological system.

[0003] Salt marsh vegetation, as a natural wave-dissipating structure, has a significant wave energy dissipation effect. Salt marsh vegetation interacts with waves through its stem and leaf structure, dissipating wave energy and reducing the impact of waves on the shoreline. However, the wave dissipation effect of salt marsh vegetation is greatly influenced by tidal level changes and tidal flat gradients. Tidal level changes result in changes in water depth, affecting wave propagation paths and energy dissipation efficiency; tidal flat gradients affect the degree of wave attenuation during propagation. Therefore, accurately calculating the wave dissipation effect of salt marsh vegetation under different tidal levels and gradients is of great significance for ecological protection and management in coastal regions.

[0004] To better understand and predict the wave dissipation effect of salt marsh vegetation under different tidal levels and gradients, an accurate wave energy attenuation model needs to be established. This model should consider factors such as tidal level changes, tidal flat gradients, vegetation types, densities, and heights, and calibrate and verify model parameters through physical model tests and numerical simulations, thereby providing scientific basis and technical support. SUMMARY

[0005] The present application provides a method and system for calculating the wave dissipation effect of salt marsh vegetation at different gradients under changing tidal levels.

[0006] To achieve the above-mentioned purpose, the following technical solutions are adopted:

[0007] A method for calculating the wave dissipation effect of salt marsh vegetation at different gradients under changing tidal levels, characterized by the following steps:

[0008] Performing a physical model test of wave incidence on salt marsh vegetation in the tidal flat area to obtain the energy dissipation amount of waves after passing through the vegetation area and the wave reflection amount in the vegetation area;

[0009] Determining the vegetation energy dissipation based on the arrangement specifications of salt marsh vegetation in the tidal flat area, the energy dissipation amount, and the wave reflection amount.

[0010] To optimize the above technical solutions, the specific measures taken also include:

[0011] Further, the construction process of the physical model is as follows:

[0012] Select suitable salt marsh vegetation species in the tidal flat area, and classify them according to the tidal level;

[0013] Adjust the density and height of the vegetation according to the change of the tidal level, so that it can dissipate wave energy at different tidal levels.

[0014] Further, the classification according to the tidal level is specifically: the selected vegetation species are classified into low-tidal flat vegetation, middle-tidal flat vegetation, high-tidal flat vegetation and near-shore vegetation according to the tidal level from low to high.

[0015] Further, the formula of the vegetation energy dissipation is as follows:

[0016]

[0017] In the formula, D v represents the vegetation energy dissipation, is the vegetation stem and leaf correction coefficient, ρ is the fluid density, C d is the drag coefficient, d is the vegetation diameter, H is the wave height, T is the wave period, k is the wave number, h is the water depth, h v is the vertical position, and N is the vegetation density per unit area.

[0018] Further, in the process of determining the vegetation energy dissipation, the change of the tidal level and the tidal level gradient are considered, and the formula of the vegetation energy dissipation is as follows:

[0019]

[0020] In the formula, D v represents the vegetation energy dissipation, is the vegetation stem and leaf correction coefficient, ρ is the fluid density, C d is the drag coefficient, d is the vegetation diameter, H is the wave height, T is the wave period, k is the wave number; h(t,x) represents the water depth at position x and time t, h0 is the initial tidal level, A i is the amplitude of the i-th tidal component, ω i is the frequency of the i-th tidal component, φ i is the phase angle of the i-th tidal component, n is the number of tidal components, and G(x) represents the tidal level gradient, h vi and N irespectively are the vertical position and the vegetation density per unit area corresponding to the i th tidal component.

[0021] Further, the vegetation diameter d and the vegetation density N per unit area are determined according to the salt marsh vegetation arrangement specification. i According to the salt marsh vegetation arrangement specification;

[0022] The drag coefficient C d According to the wave dissipation efficiency, the simulated wave dissipation efficiency of the salt marsh vegetation is calculated according to the initial drag coefficient, and it is judged whether the simulated wave dissipation efficiency of the salt marsh vegetation is equal to the actual wave dissipation efficiency; if equal, the initial drag coefficient is taken as the drag coefficient C d , otherwise the initial drag coefficient is adjusted until the simulated wave dissipation efficiency is equal to the actual wave dissipation efficiency, and the adjusted drag coefficient is taken as the drag coefficient C d .

[0023] Correspondingly, the present application provides a calculation system for the wave dissipation effect of different gradient salt marsh vegetation under varying tidal level, characterized in that it comprises:

[0024] An input module is configured to input tidal level variation data, tidal flat gradient data and salt marsh vegetation arrangement specification data, and generate a mathematical model of tidal level variation and tidal flat gradient;

[0025] A calculation unit is configured to obtain a calculation model of vegetation energy dissipation according to the mathematical model of tidal level variation and tidal flat gradient, in combination with the salt marsh vegetation arrangement specification data;

[0026] A calibration module is configured to calibrate the calculation model to ensure that the calculation result of the calculation model is consistent with the actual result;

[0027] An output module is configured to output the calculation result, including the vegetation energy dissipation of the salt marsh vegetation under different tidal levels and gradients.

[0028] Further, the mathematical model of tidal level variation and tidal flat gradient is generated, specifically as follows:

[0029] Record and input the variation data h(t) of the tidal level with time t, and generate the tidal level variation rate

[0030] Record and input the water depth data h(x) of the tidal flat at different positions x, and generate the tidal level gradient

[0031] The salt marsh vegetation arrangement specification data includes the type, density, height and distribution mode of the vegetation.

[0032] Further, the calculation model of vegetation energy dissipation is as follows:

[0033]

[0034] In the formula, D v represents the vegetation energy dissipation, is a vegetation stem leaf correction coefficient, p is a fluid density, C d is a drag coefficient, d is a vegetation diameter, H is a wave height, T is a wave period, k is a wave number; h(t, x) represents a water depth at a position x and a time t, h0 is an initial tidal level, A i is an amplitude of an i-th tidal component, ω i is a frequency of the i-th tidal component, φ i is a phase angle of the i-th tidal component, n is a number of tidal components, G(x) represents a tidal level gradient, h vi and N i are a vertical position and a vegetation density per unit area corresponding to the i-th tidal component, respectively.

[0035] Further, the calibration module obtains an energy dissipation amount and a wave reflection amount in the vegetation area after the wave passes through the vegetation area by performing a physical model test of wave incidence on the salt marsh vegetation of the tidal flat area, and calibrates the vegetation diameter d, the vegetation density N i per unit area, and the drag coefficient C d in the calculation model based on the physical model test results.

[0036] The present application has the beneficial effects that: the present application establishes a mathematical model of tidal level change and tidal flat gradient, combines the physical properties of vegetation, calculates the water depth at different times and positions, and further calculates the energy dissipation effect of salt marsh vegetation under different tidal levels and gradient conditions. Such design can calculate the salt marsh vegetation wave dissipation effect under different tidal gradients while considering the tidal level change, tidal flat gradient and salt marsh vegetation wave dissipation efficiency, and improve the calculation accuracy. The present application can not only accurately predict the wave dissipation effect of vegetation, but also provide effective technical support for the protection and restoration of coastal ecosystems. The proposed calculation method and system have the characteristics of science, practicality, accuracy, efficiency and the like, and are suitable for port, coastal protection engineering, ecological restoration and coastal zone management fields. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a flow chart of a calculation method of salt marsh vegetation wave dissipation effect under different gradients of varying tidal levels.

[0038] Figure 2 is an architecture diagram of a calculation system of salt marsh vegetation wave dissipation effect under different gradients of varying tidal levels.

[0039] Figure 3 is a physical model diagram of salt marsh vegetation established.

[0040] Figure 4 It is a schematic diagram of tidal changes, gradients, and vegetation distribution. Detailed Implementation

[0041] The invention will now be described in further detail with reference to the accompanying drawings.

[0042] Example 1

[0043] like Figure 1 As shown in this embodiment, a method for calculating the wave dissipation effect of salt marsh vegetation with different gradients under varying tidal levels is proposed. The technical concept is as follows: for salt marsh vegetation layouts with different tidal levels and gradients, considering the influence of tidal level changes and tidal flat gradients on the wave dissipation effect, the energy dissipation under different vegetation types and densities is determined as the basic parameters for calculating the wave dissipation effect; based on the wave dissipation characteristics of vegetation, different vegetation types are numerically generalized and parameterized to determine the parameterization scheme of vegetation wave dissipation; combining the parameterization schemes of tidal level changes, tidal flat gradients, and vegetation wave dissipation, and using the wave energy dissipation formula as the calculation carrier, a method for calculating the wave dissipation effect of salt marsh vegetation with different gradients under varying tidal levels is constructed.

[0044] The calculation method specifically includes the following steps:

[0045] S1: Considering tidal changes and tidal flat gradients, and combining the layout of salt marsh vegetation under different tidal levels and gradients, determine the energy dissipation under different vegetation types and densities; the vegetation layout specifications include the type, density, height and distribution pattern of vegetation.

[0046] (1) Vegetation Selection: Select suitable salt marsh vegetation species in the tidal flat area. Classify them according to tidal level from low to high, including low-tide flat vegetation, mid-tide flat vegetation, high-tide flat vegetation, and nearshore vegetation. For example, low-tide flat vegetation includes submerged plants such as *Scirpus maritimus*. Mid-tide flat vegetation includes salt-tolerant plants such as *Suaeda salsa* and *Tamarix chinensis*. High-tide flat vegetation includes emergent plants such as reeds (*Phragmites australis*). Nearshore vegetation includes mangroves (*Rhizophora stylosa*) and coastal pines (*Casuarina equisetifolia*).

[0047] (2) Adjust the density and height: Adjust the density and height of the vegetation according to the change of tidal level, so that it can effectively dissipate wave energy under different tidal levels. The specific method includes: first, collect the tidal level change data through the tidal level monitoring system, and establish the tidal level change model; then, according to the tidal level change model, determine the optimal density and height combination of the vegetation under different tidal levels. The method of adjusting the density of vegetation includes planting vegetation with different densities in the laboratory or on site, and evaluating its wave dissipation effect through wave tank experiment or field monitoring to determine the optimal density. The method of adjusting the height of vegetation includes selecting vegetation varieties with different heights to adapt to different tidal level conditions, and verifying their wave dissipation effect through experiment or monitoring.

[0048] (3) Simulate the wave dissipation process of vegetation: Through physical model test, determine the energy dissipation and wave dissipation effect of vegetation. Place the physical model of salt marsh vegetation in the water tank, and collect the designed wave, which includes wave height, wave period and wave incidence direction. According to the designed wave, carry out artificial wave making to carry out physical model test of wave incidence, and determine the energy dissipation amount of wave after passing through the salt marsh vegetation area and the wave reflection amount in the salt marsh vegetation area. Specifically, arrange the vegetation model with selected and adjusted density and height in the water tank, set different wave height and period conditions, and record the wave dissipation change data before and after the vegetation area through wave height instrument.

[0049] S2: Considering the wave dissipation effect of salt marsh vegetation, determine the calculation formula of wave energy dissipation rate caused by salt marsh vegetation in the wave energy dissipation model. Under certain numerical constraint conditions (such as vegetation height, density and arrangement spacing, etc.), according to the arrangement specifications of salt marsh vegetation in the tidal flat area, determine the energy dissipation through energy dissipation amount and wave reflection amount.

[0050] Considering the influence of salt marsh vegetation arrangement density and tidal level change on wave energy dissipation, determine the energy dissipation under different vegetation types and densities. The higher the vegetation density, the greater the energy dissipation. The value of energy dissipation is based on the principle of wave energy conservation to ensure the rationality of energy dissipation. The reasonable value of energy dissipation can be determined through comprehensive analysis of physical model test results and vegetation arrangement in the tidal flat area, and the determined energy dissipation is taken as the basic parameter for calculating the wave dissipation effect.

[0051] The process of determining the parameterization scheme of the salt marsh vegetation wave dissipation includes: based on the wave dissipation characteristics of the salt marsh vegetation, the wave dissipation efficiency of the vegetation is numerically generalized and parameterized, and the parameterization scheme of the vegetation wave dissipation is determined. The wave energy attenuation caused by the vegetation can be obtained by calculating the work done by the resistance of the vegetation to the fluid, which is similar to the traditional wave dissipation process. Therefore, the wave energy attenuation caused by the vegetation can be obtained by calculating the work done by the resistance of the vegetation to the fluid. When this method is used, it is assumed that the resistance of the vegetation to the fluid plays a dominant role, and the influence of the inertial force is ignored. The specific calculation process is as follows:

[0052] ①The density of wave energy is the sum of potential energy density and kinetic energy density, and the formula is:

[0053]

[0054] Where, ρ is the fluid density, g is the acceleration of gravity, and H is the wave height.

[0055] ②The speed of energy transmission of wave energy in the propagation process is equal to the group velocity c g , and the calculation formula is:

[0056] c g =n·c

[0057] Where, c is the speed of a single wave, and n is usually expressed as:

[0058]

[0059] ③The expression of wave number k is:

[0060]

[0061] Where, L is the wavelength, and the expression of the wavelength is:

[0062]

[0063]

[0064] ④The energy dissipation has a negative term, represented by -D, and has:

[0065]

[0066] Where, x is the length of the wave passing through the vegetation area.

[0067] ⑤The wave energy dissipation of the vegetation is represented by D v :

[0068]

[0069] ⑥The total energy dissipation formula is:

[0070]

[0071] ⑦Wave horizontal orbital velocity U orb (z) The formula changes with depth:

[0072]

[0073] U orb is the amplitude of the horizontal orbital velocity; ω = 2π / T is the angular frequency, where T is the period of the wave; a = H / 2 is the wave amplitude, H is the wave height.

[0074] ⑧The final energy dissipation formula is:

[0075]

[0076] In the formula, D v represents the energy dissipation of vegetation, is the vegetation stem-leaf correction factor, ρ is the fluid density, C d is the drag coefficient, d is the vegetation diameter, H is the wave height, T is the wave period, k is the wave number, h is the water depth, h v is the vertical position, and N is the vegetation density per unit area. The vegetation stem-leaf correction factor is determined by measuring the ratio of the volume of vegetation with stems and leaves to the volume of vegetation without stems and leaves.

[0077] Under the influence of tidal level gradient, the wave energy attenuation rate caused by salt marsh vegetation can be transformed in the wave direction by the above formula, and the specific calculation process is as follows:

[0078] ①Tidal level change rate G(t)

[0079] The tidal level change rate G(t) can be understood as the rate of change of tidal level with respect to time, which is a key parameter in the study of tidal and wave processes. In order to express the tidal level change rate G(t), it can be defined as the derivative of the tidal level h(t) with respect to time, that is:

[0080]

[0081] ②Tidal level gradient G(x)

[0082] The tidal level gradient refers to the change of water depth (tidal level) at different positions on the tidal flat, which can be described by the relationship between water depth and horizontal distance. For example, set a reference point (such as the high tide line or low tide line), and the horizontal distance from the reference point to the specified position is x, and the water depth is h(x). The tidal level gradient can be expressed as the rate of change of water depth with respect to horizontal distance, that is:

[0083]

[0084] To incorporate the effects of tidal level change rate and gradient in the formula, both time and water depth can be combined to obtain the variation of tidal level with time and horizontal distance through experiments or observational data. It can be considered to combine the tidal level change rate G(t) with the gradient G(x) at the horizontal position x to form a comprehensive tidal level change model.

[0085] Assuming that the tidal level change can be represented as a function h(t, x), which is the tidal level varying with time and position. The tidal level change rate G and the horizontal gradient can be represented as:

[0086]

[0087]

[0088] The astronomical tide can be approximated as a sinusoidal wave model to describe the periodic variation of tidal level with time. This model is commonly used for simple tidal analysis and prediction, and a comprehensive model is used to represent the variation of water depth with time and position:

[0089]

[0090] where h0 is the initial tidal level, A i is the amplitude of the i-th tidal component, ω i is the frequency of the i-th tidal component, φ i is the phase angle of the i-th tidal component, and n represents the number of tidal components.

[0091] ③The influence of tidal level on the energy dissipation formula

[0092] To incorporate the influence of tidal level change in the energy dissipation formula, the time factor can be considered when calculating the water depth h, so that the energy dissipation formula is more accurate. The specific formula is as follows:

[0093]

[0094] Figure 4 The variation of tidal level with time and the variation of water depth at different positions on the tidal flat are shown, the tidal level change rate G(t) and the tidal level gradient G(x) are generated, and the arrangement of different salt marsh vegetation is shown.

[0095] In the above formula, only the vegetation drag coefficient, vegetation diameter and the number of vegetation per square meter are unknown, so in this embodiment, a specific determination method is given: in the wave energy attenuation rate calculation formula, the vegetation diameter d and the number of vegetation per square meter N can be set according to the specifications of salt marsh vegetation (i.e. the type, quantity, size, arrangement position and spacing of vegetation), and the vegetation drag coefficient C dThe calibration needs to be made according to the wave dissipation efficiency. According to the existing research results of the physical model test of the salt marsh vegetation wave dissipation efficiency, the specifications and arrangement modes of the vegetation result in certain differences in the wave dissipation efficiency, and the wave height attenuation percentage caused by the vegetation is between 85% and 95%. The types, quantity, size, layout position and spacing of the salt marsh vegetation in the tidal flat area to be researched are collected, the wave dissipation efficiency of the vegetation is determined according to the existing research results of the physical model test of the salt marsh vegetation wave dissipation efficiency, the relationship between the wave energy attenuation and the vegetation drag coefficient is analyzed by using the selected wave calculation model in combination with the wave dissipation efficiency of the vegetation, the reasonable value of the vegetation drag coefficient C d is determined, and on this basis, the parameterization scheme of the salt marsh vegetation wave dissipation is determined.

[0096] Specifically, the determination method of the vegetation drag coefficient, the vegetation diameter and the vegetation quantity per square meter includes:

[0097] (1) The vegetation diameter d and the vegetation quantity per square meter N are determined according to the salt marsh vegetation specifications in the planar arrangement of the tidal flat area, and the vegetation specifications include the types, quantity, size, layout position and spacing of the vegetation.

[0098] Specifically, the size of the salt marsh vegetation is taken as the vegetation diameter, and the density of the salt marsh vegetation is taken as the vegetation quantity per square meter.

[0099] (2) The physical model of the salt marsh vegetation is established based on the vegetation specifications, the physical model of the vegetation (as shown in FIG. 1) is subjected to the physical model test of wave incidence, and the actual wave dissipation efficiency of the vegetation is determined. Figure 3

[0100] The physical model of the salt marsh vegetation is constructed by proportionally reducing the vegetation specifications, the physical model of the salt marsh vegetation is placed in a water tank, artificial wave making is made according to the designed wave to determine the actual wave dissipation efficiency of the salt marsh vegetation.

[0101] (3) The initial vegetation drag coefficient is determined: the wave energy attenuation rate calculation formula containing the initial vegetation drag coefficient is input into the wave calculation model to obtain a first calculation model, the simulation wave dissipation efficiency of the salt marsh vegetation is calculated by using the first calculation model, it is judged whether the simulation wave dissipation efficiency is equal to the actual wave dissipation efficiency, if yes, the initial vegetation drag coefficient is taken as the vegetation drag coefficient, if no, the initial vegetation drag coefficient is adjusted to obtain an adjusted value, and the adjusted value is taken as the initial vegetation drag coefficient of the next cycle, and the step of “the wave energy attenuation rate calculation formula containing the initial vegetation drag coefficient is input into the wave calculation model” is returned.

[0102] It needs to be noted that in the wave energy attenuation rate calculation formula containing the initial vegetation drag coefficient, the vegetation diameter and the vegetation quantity per square meter are the vegetation diameter and the vegetation quantity per square meter determined according to the salt marsh vegetation specifications in the tidal flat area.​

[0103] Next, the method proposed in this embodiment will be illustrated in combination with a specific application case.

[0104] An experiment was conducted in a tidal flat area, aiming to calculate the energy dissipation of a certain salt marsh vegetation under different tidal levels and tidal flat gradients. The selected vegetation type was Phragmites australis, and its related parameters were as follows:

[0105] Vegetation diameter d = 0.01 meters; vegetation density N = 200 plants per square meter; drag coefficient C d = 1.0; fluid density p = 1000 kg / m3; wave height H = 0.5 meters; wave period T = 8 seconds; vertical position h v = 0.5 meters; tidal flat length L = 100 meters; height difference H tide = 2 meters.

[0106] In addition, the tidal level change rate G(x) was calculated, with the wave period of the tidal level changing over time being T tide and the wave amplitude being A. The parameters were as follows: initial tidal level h0 = 1.0 meters; tidal level change amplitude A = 0.5 meters; wave period T tide = 12 hours.

[0107] The change of the tidal level over time can be represented as:

[0108]

[0109] The tidal level change rate G(t) is:

[0110]

[0111] The tidal flat gradient G(x) is:

[0112]

[0113] Assuming that at a specific time point t = 3 hours, the tidal level h(t) and the tidal level change rate G(t) are respectively:

[0114]

[0115]

[0116] Substituting the tidal level h = 1.5 meters and the tidal flat gradient G(x) = 0.02 into the formula to calculate:

[0117] The wave number k is calculated as follows:

[0118]

[0119] The wavelength l is calculated as:

[0120]

[0121] The wave number k is calculated as follows:

[0122]

[0123] Then, the energy dissipation D of the vegetation is calculated as follows: v

[0124]

[0125] Therefore, under the given conditions, the energy dissipation of the reed vegetation is about 1.54.

[0126] The calculation of the above example shows how to calculate the energy dissipation of the salt marsh vegetation under different tidal levels according to the changes of tidal level and gradient. This method provides a scientific basis for studying and applying the wave dissipation effect of salt marsh vegetation.

[0127] Example Two

[0128] As shown in the following figure, the present example proposes a calculation system for the wave dissipation effect of salt marsh vegetation under different gradients with changing tidal levels, which corresponds to the calculation method proposed in Example One. The system mainly includes the following modules: Figure 2

[0129] (1) Input module

[0130] The input module is used to input the tidal level change data, the tidal flat gradient data and the salt marsh vegetation specification data to generate a mathematical model of tidal level change and tidal flat gradient. Specifically, the input module includes the following parts:

[0131] Tidal level change input unit: records and inputs the data h(t) of the change of tidal level with time, and generates the rate of change of tidal level

[0132] Tidal flat gradient input unit: records and inputs the water depth (tidal level) data h(x) of different positions of the tidal flat, and generates the tidal level gradient

[0133] Vegetation specification input unit: records and inputs the type, density, height and distribution method of the salt marsh vegetation, and generates the arrangement specification of the salt marsh vegetation.

[0134] (2) Calculation module

[0135] The calculation module is used to calculate the wave energy attenuation rate according to the tidal level change and tidal flat gradient model, combined with the vegetation drag coefficient, vegetation diameter and the number of vegetation per square meter. Specifically, the calculation module includes the following parts:

[0136] ​​Tide level change calculation unit: calculates the rate of tide level change G(t) and the tide level gradient G(x).

[0137] Wave energy attenuation calculation unit: based on the input data and formula Calculate the wave energy attenuation rate D v .

[0138] (3) Calibration module

[0139] The calibration module is used to calibrate the calculation model according to the physical model test results, to ensure that the calculation results are consistent with the actual situation. Specifically, the calibration module includes the following parts:

[0140] Physical model test unit: through physical model test, get the wave energy attenuation data and reflection data under different vegetation arrangement.

[0141] Data calibration unit: based on the physical model test results, calibrate the drag coefficient C d , vegetation diameter d and the number of vegetation per square meter N in the calculation model, to ensure the accuracy of the calculation results.

[0142] (4) Output module

[0143] The output module is used to output the calculation results, including the wave energy attenuation effect of salt marsh vegetation under different tide levels and gradients. Specifically, the output module includes the following parts:

[0144] Result display unit: display the wave energy attenuation effect under different tide levels and gradients in the form of charts.

[0145] Data export unit: export the calculation results as a report for users to further analyze and make decisions.

[0146] (5) Database module

[0147] The database module is used to store and manage input data, calculation results and calibration data, to ensure the continuity of the system and the traceability of the data. Specifically, the database module includes the following parts:

[0148] Data storage unit: store tide level change data, tidal flat gradient data, salt marsh vegetation specification data and physical model test data.

[0149] Data management unit: classify and manage the stored data to ensure data integrity and availability.

[0150] In this system, the functions, principles and workflows of each module and unit are the same as the calculation method proposed in embodiment one, so the repeated content will not be repeated here.

[0151] The above are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical scheme falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled in the art, some improvements and refinements without departing from the principles of the present application shall be considered as the protection scope of the present application.

Claims

1. A method for calculating the wave-dissipation effect of different gradient salt marsh vegetation under varying tidal levels, characterized in that, The method comprises the following steps: A physical model test of wave incidence on salt marsh vegetation in a tidal flat area is performed to obtain energy dissipation and wave reflection in the vegetation area after wave passing through the vegetation area; Vegetation energy dissipation is determined according to the arrangement specification of salt marsh vegetation in the tidal flat area, the energy dissipation and the wave reflection, and the process of determining the vegetation energy dissipation considers the tidal level change and the tidal level gradient, and a formula of the vegetation energy dissipation is as follows: wherein represents the energy dissipation of vegetation, is the correction coefficient of vegetation stem and leaf, is the fluid density, is the drag coefficient, is the diameter of vegetation, is the wave height, is the wave period, is the wave number; represents the water depth at position and time , , is the initial tidal level, is the amplitude of the i th tidal component, is the frequency of the i th tidal component, is the phase angle of the i th tidal component, n is the number of tidal components, represents the tidal level gradient, ; and are the vertical position and the vegetation density per unit area corresponding to the i th tidal component, respectively.

2. The method for calculating the wave-dissipating effect of salt marsh vegetation with different gradients under varying tidal levels as described in claim 1, characterized in that: The construction process of the physical model is as follows: Suitable salt marsh vegetation species are selected in the tidal flat area, and the vegetation is classified according to the tidal level; The density and height of the vegetation are adjusted according to the tidal level change, so that the vegetation can dissipate wave energy under different tidal levels.

3. The method according to claim 2, wherein the tidal range is 2.0 m or more. The classification according to the tidal level is specifically that the selected vegetation species are classified into low-tidal flat vegetation, middle-tidal flat vegetation, high-tidal flat vegetation and near-shore vegetation according to the tidal level from low to high. ​ 4. The method according to claim 1, wherein the tidal range is different. 1 The vegetation diameter And the vegetation density per unit area According to the salt marsh vegetation arrangement specification; The drag coefficient According to the calibration of the wave dissipation effect: according to the initial drag coefficient, the simulated wave dissipation effect of the salt marsh vegetation is calculated, and it is judged whether the simulated wave dissipation effect of the salt marsh vegetation is equal to the actual wave dissipation effect; if equal, the initial drag coefficient is taken as the drag coefficient , otherwise, the initial drag coefficient is adjusted until the simulated wave dissipation effect is equal to the actual wave dissipation effect, and the adjusted drag coefficient is taken as the drag coefficient .

5. A system for calculating the wave dissipation effect of different gradient salt marsh vegetation under varying tidal levels, characterized in that, The method comprises the following steps: An input module is configured to input tidal level change data, tidal flat gradient data and salt marsh vegetation arrangement specification data, and generate a mathematical model of the tidal level change and the tidal flat gradient; A calculation unit is configured to obtain a calculation model of vegetation energy dissipation according to the mathematical model of the tidal level change and the tidal flat gradient in combination with the salt marsh vegetation arrangement specification data, and the calculation model of the vegetation energy dissipation is as follows: In the formula, This indicates energy dissipation from vegetation. This is the correction factor for vegetation stems and leaves. For fluid density, This is the drag coefficient. The diameter of the vegetation. For wave height, For fluctuation cycle, Wave number; Indicates position and time The water depth at that location , It is the initial tide level. It is the first i The amplitude of each tidal component, It is the first i The frequency of each tidal component, It is the first i The phase angle of each tidal component, n It is the amount of tidal components. Indicates the tidal gradient. ; and They are the first i The vertical position and vegetation density per unit area corresponding to each tidal component; A calibration module is configured to calibrate the calculation model to ensure that the calculation result of the calculation model is consistent with the actual result; An output module is configured to output the calculation result, including vegetation energy dissipation of salt marsh vegetation under different tidal levels and gradients.

6. A system for calculating the wave dissipation effect of different gradient salt marsh vegetation under varying tidal levels according to claim 5, characterized in that: The mathematical model of the tidal level change and the tidal flat gradient is specifically as follows: Record and input tide levels over time Change data And generate the rate of tidal change. ; Record and input different locations of the tidal flats water depth data Generate tidal gradient ; The salt marsh vegetation arrangement specification data includes the species, density, height and distribution mode of the vegetation.

7. A system for calculating the wave dissipation effect of different gradient salt marsh vegetation under varying tidal levels as claimed in claim 5, characterized in that: The calibration module obtains the energy dissipation amount after the wave passes through the vegetation area and the wave reflection amount in the vegetation area by performing a physical model test of wave incidence on the salt marsh vegetation in the tidal flat area, and calibrates the vegetation diameter , the vegetation density per unit area , and the drag coefficient in the calculation model based on the physical model test results.

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