Seabed erosion and deposition risk assessment method and device

Abstract

The invention discloses a seabed erosion and deposition risk assessment method and device. The method comprises the following steps: acquiring underwater topographic data, hydrological observation data and seabed sediment data of an engineering sea area; according to the hydrological observation data and the underwater topographic data, calculating to obtain a hydrodynamic condition by utilizing a tidal current numerical model and a wave numerical model; wherein the hydrodynamic conditions comprise tidal flow velocity, tidal cycle, wave height and wave cycle; inputting seabed sediment data into the trained sediment starting model, and outputting to obtain sediment starting conditions; wherein the sediment starting condition comprises a starting flow rate and a starting wave height; and carrying out risk grade division on the engineering sea area according to the underwater topographic data, the hydrodynamic condition and the sediment starting condition to obtain a seabed erosion and deposition risk assessment result. According to the seabed erosion and deposition risk assessment method and device provided by the invention, the accuracy of seabed erosion and deposition risk assessment is improved, the risk grade index is clearly quantified, and engineering practice can be directly guided.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering and offshore wind power technology, and specifically relates to a method and device for assessing seabed erosion and siltation risks. Background Technology

[0002] Offshore wind power is an important clean energy source, and its sites are often located in nearshore areas with strong hydrodynamics and active sediment movement. Changes in the seabed due to erosion and deposition directly threaten the long-term stability and safety of facilities such as wind turbine foundations, submarine cables, and substations. Traditional methods for assessing the risk of pile foundation scour often have the following limitations:

[0003] 1. Due to the lack of clear technical standards, the standards and methods for determining the scour protection range are not uniform in actual offshore wind farm projects.

[0004] 2. Judgments are often based solely on historical topographic comparisons or simple dynamic parameters (such as flow velocity and wave height), resulting in limited judgment elements and low accuracy.

[0005] 3. The conclusions are mostly qualitative descriptions, such as "severe scouring and silting" and "relatively stable," lacking quantitative and gradable risk assessment standards, making it difficult to directly guide engineering design.

[0006] 4. It mainly relies on historical data and lacks the ability to predict future evolution trends, making it unable to provide a forecast of scour risks within the design service life.

[0007] Therefore, there are currently no clear regulations on the methods for scour risk zoning of offshore wind farms, and existing engineering practices are not conducive to the economical and rational planning of offshore wind turbine locations. Summary of the Invention

[0008] Objective: In order to overcome the shortcomings of the existing technology, the present invention provides a method and apparatus for assessing seabed erosion and sedimentation risks.

[0009] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0010] Firstly, a method for assessing seabed erosion and deposition risks is provided, the method including:

[0011] Acquire underwater topographic data, hydrological observation data, and seabed sediment data of the engineering area;

[0012] Based on hydrological observation data and underwater topographic data, hydrodynamic conditions are calculated using tidal current numerical models and wave numerical models; wherein, the hydrodynamic conditions include tidal current velocity, tidal current period, wave height and wave period;

[0013] Seabed sediment data is input into a trained sediment initiation model, and sediment initiation conditions are output; wherein, the sediment initiation conditions include initiation flow velocity and initiation wave height;

[0014] Based on underwater topographic data, hydrodynamic conditions, and sediment initiation conditions, the risk level of the project area is classified, resulting in a risk assessment of seabed erosion and deposition.

[0015] This scheme first establishes numerical models for tidal currents and waves, using underwater topographic data as the topographic input for the computational domains of these models. After verification with measured hydrological data, hydrodynamic conditions are simulated. Second, sediment initiation conditions are calculated, and the hydrodynamic and sediment initiation conditions are compared to analyze sediment mobility. Combined with underwater topographic data, historical topographic evolution is analyzed. This multi-dimensional assessment based on the above factors enhances the accuracy of the evaluation results. Simultaneously, risk levels are clearly quantified, risk zones are planned from low to high, and facility layout suggestions are provided, directly guiding engineering practice.

[0016] In some embodiments, the underwater topographic data includes underwater slope, erosion rate, and isobath movement speed;

[0017] And / or, the hydrological observation data includes tidal level, current velocity, current direction, observed wave height, and wave number;

[0018] And / or, the seabed sediment data includes the diameter of sediment particles.

[0019] In some embodiments, the calculation of hydrodynamic conditions based on hydrological observation data and underwater topographic data using tidal current numerical models and wave numerical models includes:

[0020] Underwater topographic data is used as the computational domain for the tidal current numerical model and the wave numerical model;

[0021] Hydrological observation data will be used to validate numerical models of tidal currents and waves.

[0022] Hydrodynamic conditions were calculated using the validated numerical models of tidal current and waves.

[0023] In some embodiments, the governing equations of the power flow numerical model include:

[0024] Continuity equation:

[0025] ;

[0026] Momentum equation in the X-axis direction:

[0027] ;

[0028] Y-axis momentum equation:

[0029] ;

[0030] Z-axis momentum equation:

[0031] ;

[0032] Where x, y, and z are the spatial coordinates along the X, Y, and Z axes, u is the flow velocity along the X-axis, v is the flow velocity along the Y-axis, w is the flow velocity along the Z-axis, t is time, and f is the Coriolis parameter. , The angular velocity of Earth's rotation. Latitude For reference density, For pressure, The vertical eddy viscosity coefficient is... The horizontal eddy viscosity coefficient. For the horizontal gradient operator, , Where is the actual density, and g is the acceleration due to gravity.

[0033] In some embodiments, the governing equations of the wave numerical model include:

[0034] Boussinesq-like equations describe the nonlinear propagation, refraction, diffraction, and shallowing processes of waves from deep water to shallow water (until they break apart):

[0035] ;

[0036] ;

[0037] Phase-averaged model (spectral model): The spatiotemporal evolution of the wave spectrum is the industry standard for wind and wave forecasting and propagation simulation. The governing equations are the wave action balance equations:

[0038] ;

[0039] in, For function At horizontal position (x, y) and time t, the vertical height of the actual water surface relative to the still water surface, where h is the water depth. Let be the horizontal velocity vector representing the average water depth or reference water depth in the vertical direction, g be the acceleration due to gravity, and D be a vector including higher-order dispersion, dissipation, and bottom friction dissipation. Higher-order terms are introduced to correct the frequency dispersion relation, making it applicable to finite water depths. N is the wave action density spectrum. F is the energy spectral density, and f is the frequency. The wave direction is represented by x and y, which are the spatial coordinates along the X and Y axes, respectively, and t is the time interval. The natural angular frequency, , Group velocity controls the spatial propagation of wave energy. The frequency translation velocity is caused by the background flow field and wind. The directional translational velocity is caused by the background flow field and wind. The source and sink terms include wind energy input, wave-wave nonlinear interaction, dissipation, and low-friction dissipation. For vertical gradient operators; For the vector gradient operator, the three-dimensional form is: Two-dimensional form is The dot product of a scalar function and a vector function is a scalar; The horizontal gradient operator in the X-axis direction. .

[0040] In some embodiments, the formula for calculating the starting flow rate is as follows:

[0041] ;

[0042] in, To start the flow rate, Where is the diameter of the sediment particles, and h is the water depth. For the specific density of water, It is the bulk density of silt.

[0043] And / or, the formula for calculating the starting wave height is as follows:

[0044] ;

[0045] in, For the starting wave height, Where L is the wavelength, g is the acceleration due to gravity, and h is the water depth. For wave number, For the specific density of water, The bulk density of silt, The diameter of the sediment particles. for , is the adhesion coefficient.

[0046] In some embodiments, the criteria for classifying risk levels include:

[0047] If the underwater slope is greater than 1:30, the downcutting rate is greater than 0.2 m / a or the isobath movement speed is greater than 40 m / a, the period when the tidal current velocity is greater than the sediment initiation velocity is greater than 4 hours / tidal cycle, and the frequency when the wave height is greater than the initiation wave height is greater than 20%, it is judged as high risk.

[0048] The underwater slope is 1:(30~50), the downcutting rate is 0.1~0.2 m / a or the isobath movement speed is 20~40 m / a, the period when the tidal current velocity is greater than the sediment initiation velocity is 2~4 hours / tidal cycle, and the wave height is greater than the initiation wave frequency is 5%~20%, which is judged as medium risk.

[0049] If the underwater slope gradient is less than 1:50, the downcutting rate is less than 0.1 m / a or the isobath movement speed is less than 20 m / a, the period during which the tidal current velocity is greater than the sediment initiation velocity is less than 2 hours / tidal cycle, and the frequency of wave height being greater than the initiation wave height is less than 5%, it is judged as low risk.

[0050] In some embodiments, the risk assessment results are automatically presented in the form of a visualized comprehensive risk zoning map, while providing optimization suggestions for the layout of wind farm facilities to directly guide engineering practices.

[0051] Secondly, a seabed erosion and deposition risk assessment device is provided, comprising:

[0052] Acquisition module: used to acquire underwater topographic data, hydrological observation data, and seabed sediment data of the engineering area;

[0053] The calculation module is used to calculate hydrodynamic conditions based on hydrological observation data and underwater topographic data, using tidal current numerical models and wave numerical models; wherein, the hydrodynamic conditions include tidal current velocity, tidal current period, wave height and wave period;

[0054] Seabed sediment data is input into a trained sediment initiation model, and sediment initiation conditions are output; wherein, the sediment initiation conditions include initiation flow velocity and initiation wave height;

[0055] Risk assessment module: This module is used to classify the risk level of the engineering sea area based on underwater topographic data, hydrodynamic conditions, and sediment initiation conditions, and obtain the seabed erosion and deposition risk assessment results.

[0056] Thirdly, a computer-readable storage medium is provided having a computer program / instructions stored thereon, which, when executed by a processor, implements the steps of the seabed erosion and deposition risk assessment method described in any one of the first aspects.

[0057] Fourthly, a computer device / system / apparatus is provided, comprising:

[0058] Memory, used to store computer programs / instructions;

[0059] A processor for executing the computer program / instructions to implement the steps of the seabed erosion and sedimentation risk assessment method described in any one of the first aspects.

[0060] Beneficial effects: The seabed erosion and sedimentation risk assessment method and apparatus provided by this invention have the following advantages:

[0061] 1. By combining topographic evolution with sediment mobility, a two-dimensional risk assessment system was constructed, resulting in more comprehensive and reliable assessment results. Clear and quantitative risk classification indicators and thresholds were proposed, and the output results can directly guide engineering practice.

[0062] 2. By combining historical data and numerical models to predict future scouring and sedimentation trends, we can provide forward-looking protection for the safety of wind farm facilities throughout their entire life cycle;

[0063] 3. It integrates data processing, model calculation, risk assessment, and visualization output into a complete assessment system, thereby improving efficiency. Attached Figure Description

[0064] Figure 1 This is a flowchart of the seabed erosion and deposition risk assessment according to an embodiment of the present invention;

[0065] Figure 2 This is a location map of the engineering project site according to an embodiment of the present invention;

[0066] Figure 3 This is a distribution diagram of the median particle size of sediment in an embodiment of the present invention;

[0067] Figure 4 This is a distribution diagram of mud and clay content in an embodiment of the present invention;

[0068] Figure 5 This is a topographic map of the marine beach and channel area in an embodiment of the present invention.

[0069] Figure 6 This is a map showing the variation of the -10 m isobath in the engineering sea area according to an embodiment of the present invention;

[0070] Figure 7 This is a map showing the variation of the -5 m isobath in the engineering sea area according to an embodiment of the present invention;

[0071] Figure 8 This is a map showing the variation of the 0 m isobath in the engineering sea area according to an embodiment of the present invention;

[0072] Figure 9 This is a map showing the distribution of tidal current velocity during high tide in the engineering sea area according to an embodiment of the present invention.

[0073] Figure 10 This is a map showing the tidal current velocity distribution in the engineering sea area according to an embodiment of the present invention.

[0074] Figure 11 This is a contour map showing the distribution of seabed sediment initiation velocity in the engineering sea area according to an embodiment of the present invention.

[0075] Figure 12This is a contour map showing the distribution of significant wave height in the engineering sea area according to an embodiment of the present invention.

[0076] Figure 13 This is a comprehensive risk zoning map of the engineering project site according to an embodiment of the present invention. Detailed Implementation

[0077] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0078] The present invention will be further described below with reference to specific embodiments.

[0079] Example 1: Taking an offshore wind power project as an example. The seabed erosion and deposition risk assessment process is as follows: Figure 1 As shown. The project site location is as follows. Figure 2 As shown, an offshore wind power project is planned to be built in this area (within curves ABCDE), including four sites: F1, F2, F3, and F4.

[0080] We collected underwater topographic maps of this sea area from 1979, 1986, 2006, and 2022, as well as recent hydrological observation data and seabed sediment sampling data. Specific applications are as follows:

[0081] like Figure 3 and Figure 4 The diagram shows the sediment characteristics of the seabed. The sediment grain size is coarser in the shallow shoal area and finer in the deep channel area. In most areas of the sea, the median sediment grain size is above 0.15 mm, reaching 0.2 mm in the area between the F2 and F4 fields in the western part of the sea. The seabed sediment on the east and west sides is mainly composed of highly mobile sandy silt and clayey silt, with a median grain size mostly between 0.05 and 0.1 mm. The sediment grain size in the deep channel area is relatively finer, with the median grain size in the main channel area at depths of -15 m and above mostly less than 0.05 mm.

[0082] like Figure 2 and Figure 5 As shown, the project area exhibits a general topographic pattern of low elevations in the east and west, and high elevations in the middle, with water depths ranging from +1 to -40m, showing significant variation. Areas F1 and F2 are primarily located in deep water, with relatively stable overall channel depths, although some erosion and sedimentation have occurred on the western side of these areas in recent years. Areas F3 and F4 show a topographic distribution that is generally higher in the west and lower in the east. Using ArcGIS and MATLAB software, the underwater bank slope at different locations within the project area can be calculated based on the spatial variation of the isobaths, serving as a condition for judging the topographic pattern.

[0083] Based on underwater topographic maps from 1979 and 2022, a comparative analysis was conducted on the characteristic isobaths at -10m, -5m, and 0m (reference). Figure 6 , Figure 7 and Figure 8 The study referenced recent measured erosion and deposition changes in topographic cross-sections, primarily focusing on downcutting. Then, the horizontal and vertical downcutting rates were calculated based on the time-varying rates of specific isobaths. The vertical downcutting rate was prioritized, as it relates to the pile foundation's depth and stability.

[0084] Data on tidal level, current velocity, current direction, and sediment content, as well as wave observation data, were collected simultaneously from 4 tidal gauge stations and 12 vertical lines in the project area in 2022.

[0085] Underwater topographic data was used as the topographic input to the computational domain to construct numerical models for tidal currents and waves. The governing equations of the tidal current numerical model include:

[0086] Continuity equation:

[0087] ;

[0088] Momentum equation in the X-axis direction:

[0089] ;

[0090] Y-axis momentum equation:

[0091] ;

[0092] Z-axis momentum equation:

[0093] ;

[0094] Where x, y, and z are the spatial coordinates along the X, Y, and Z axes, u is the flow velocity along the X-axis, v is the flow velocity along the Y-axis, w is the flow velocity along the Z-axis, t is time, and f is the Coriolis parameter. , The angular velocity of Earth's rotation. Latitude For reference density, For pressure, The vertical eddy viscosity coefficient is... The horizontal eddy viscosity coefficient. For the horizontal gradient operator, , Where is the actual density, and g is the acceleration due to gravity.

[0095] The governing equations of the wave numerical model include:

[0096] ;

[0097] ;

[0098] ;

[0099] in, Where h is the vertical height of the actual water surface relative to the still water surface, and h is the water depth. Let g be the horizontal velocity vector representing the average water depth or reference water depth in the vertical direction, D be the gravitational acceleration, D be the vector including higher-order dispersion, dissipation, and bottom friction dissipation, and N be the wave action density spectrum. F is the energy spectral density, and f is the frequency. The wave direction is represented by x and y, which are the spatial coordinates along the X and Y axes, respectively, and t is the time interval. The natural angular frequency, , Group velocity controls the spatial propagation of wave energy. The frequency translation velocity is caused by the background flow field and wind. The directional translational velocity is caused by the background flow field and wind. The source and sink terms include wind energy input, wave-wave nonlinear interaction, dissipation, and low-friction dissipation. For vertical gradient operators; For vector gradient operators; This is the horizontal gradient operator in the X-axis direction.

[0100] Hydrological observation data were input into the tidal current numerical model and wave numerical model for verification. Then, the hydrodynamic conditions of the engineering sea area were calculated, including tidal current velocity, tidal current period, wave height, and wave period. Seabed sediment data were input into the trained sediment initiation model, and the sediment initiation conditions, including initiation current velocity and initiation wave height, were output.

[0101] The formula for calculating the starting flow rate is as follows:

[0102] ;

[0103] in, To start the flow rate, Where is the diameter of the sediment particles, and h is the water depth. For the specific density of water, It is the bulk density of silt.

[0104] The formula for calculating the starting wave height is as follows:

[0105] ;

[0106] in, For the starting wave height, Where L is the wavelength, g is the acceleration due to gravity, and h is the water depth. For wave number, For the specific density of water, The bulk density of silt, The diameter of the sediment particles. for , is the adhesion coefficient.

[0107] Call the validated power flow numerical model, such as Figure 9 , Figure 10 As shown, the distribution of tidal current velocities during high and low tides in the region, calculated using a tidal current numerical model, is illustrated. The tidal current velocities at various points in the region during high tides are recorded. Using the sediment initiation formula, with water depth and bottom sediment particle size as parameters, the sediment initiation velocity distribution map for the engineering area is calculated, as shown below. Figure 11 As shown, the sediment initiation status at each point is determined by comparing the magnitude of the tidal current velocity and the initiation velocity obtained from the numerical model. After sediment initiation, the severity of scouring and the duration of initiation affect how long the sediment can be transported. Using the tidal current numerical model, the cumulative time for the current velocity to exceed the initiation velocity within each tidal cycle (mainly the spring tide cycle) is calculated to make a judgment; the longer the duration, the stronger the sediment mobility.

[0108] Similarly, call the validated wave numerical model, such as Figure 12 The diagram shows the distribution of significant wave heights in the strong wave direction within the engineering area. The wave height was calculated using the initiation wave height formula, and the relationship between the significant downward wave height (Hs) derived from the model and the magnitude of the initiation wave height (Hc) was compared to determine whether initiation was possible. These determinations collectively constitute the sediment mobility index.

[0109] The sediment activity at each point was comprehensively rated based on underwater slope gradient, erosion rate, isobath movement speed, tidal current initiation period, and wave initiation wave height frequency, as shown in Table 1.

[0110] High-risk areas exhibit strong sediment activity, alternating beach-channel topography, frequent and active tidal channels and sluices, and significant variations in erosion and deposition. These areas also require steep slopes, high downcutting rates, or rapid movement of isobaths with long initiation periods, and a high frequency of Hs>Hc.

[0111] The medium-risk area exhibits moderate sediment activity, showing an erosion trend, and the seabed topography is subject to certain changes. It also meets the following criteria: moderate slope, moderate downcutting rate or moderate isobath movement speed, moderate initiation period, and low frequency of Hs>Hc occurrence.

[0112] Low-risk areas exhibit weak sediment activity, flat seabed topography, greater water depth, and less erosion and deposition fluctuations. They also typically meet the following criteria: gentle slope, low erosion rate or low isobath movement speed, short initiation period, and low frequency of Hs>Hc.

[0113] Table 1: Classification Standards for Seabed Erosion and Sedimentation Risk Levels

[0114] Risk level Sediment mobility Topographical evolution High risk The start-up cycle is greater than 4 hours per tide, and the frequency of Hs > Hc is greater than 20%. A slope greater than 1:30, a downcutting rate greater than 0.2 m / a, or a contour line movement speed greater than 40 m / a. Medium risk The starting cycle is 2-4 hours per tidal cycle, and the frequency of Hs>Hc is 5%-20%. The slope is 1:(30~50), the downcutting rate is 0.1~0.2 m / a or the isobath movement speed is 20~40 m / a. Low risk The start-up cycle is less than 2 hours per tide, and the frequency of Hs>Hc is less than 5%. The slope is less than 1:50, the downcutting rate is less than 0.1 m / a, or the isobath movement speed is less than 20 m / a.

[0115] Taking project site F2 as an example, the application conditions are judged as follows: the historical water depth variation data of the deep pit in the southeast of site F2 is as follows: Figure 6 , Figure 7 and Figure 8 Since 1979, the tidal channel has migrated northward by approximately 1.5 km, with the water depth increasing from -5 m to -10.5 m. Its planar morphology has expanded rapidly, with its length increasing from 6 km to 8 km and its width from 0.5 km to 1.1 km. The north-south extension rate is approximately 50 m / year, and the east-west widening rate is approximately 15 m / year. The maximum water depth has increased from -38 m to -40 m, and the underwater bank slope is steep (1:31). These areas, with their steep bank slopes and active tidal channels, exhibit an average annual downcutting rate greater than 0.2 m / year, reflecting strong topographic instability.

[0116] Hydrodynamic conditions further amplify the area's scour sensitivity. The maximum tidal current velocities during high and low tides reach 1.72–2.27 m / s, significantly exceeding the initial sediment initiation velocity (0.6–1.0 m / s) in the region, and the duration exceeding the critical value generally exceeds 4 hours, indicating that sediment remains in a transportable state for extended periods. Regarding waves, the initial wave height in this area is approximately 0.8–1.0 m, and the frequency of significant wave heights exceeding 1.0 m reaches 20% annually. Strong north-northwest oriented waves in winter can completely uplift bottom sediment, intensifying scouring.

[0117] In summary, the area meets the dual characteristics of drastic topographic changes and high sediment mobility, and is therefore identified as a high-risk area where wind turbine locations are not suitable.

[0118] Similarly, risk classification was carried out within the four site areas of the project's sea area, such as... Figure 13 As shown in the figure, (+) indicates the location of the fan.

[0119] Based on the different capacities of the four sites in this project, 24, 35, 18, and 23 wind turbines were installed in sites F1, F2, F3, and F4, respectively.

[0120] In terms of overall planar distribution, 7 wind turbines in the F1 area are located in the medium-risk zone; 1 wind turbine in the F2 area is located in the high-risk zone and 7 turbines in the medium-risk zone; 8 wind turbines in the F3 area are located in the medium-risk zone; and 12 wind turbines in the F4 area are located in the medium-risk zone. The overall turbine layout is consistent with the topography and seabed stability. Turbines in the high-risk zone of the F2 area were moved out of the high-risk zone, and the planar layout was slightly adjusted accordingly. Three turbines in the F1 area were moved from the medium-risk zone to the low-risk zone. Facilities in the medium-risk zone are designed with a buffer depth for scour, which is the greater of "scour volume calculated from historical scour rates to the design service life" and "the maximum water depth that has occurred historically," and is recommended to be no less than 5 m. The low-risk zone is the preferred layout area, and the foundation design considers a 1-2 m allowance for natural scour.

[0121] Example 2: Based on the same inventive concept as Example 1, this embodiment of the invention discloses a seabed erosion and deposition risk assessment device, comprising:

[0122] Acquisition module: used to acquire underwater topographic data, hydrological observation data, and seabed sediment data of the engineering area;

[0123] The calculation module is used to calculate hydrodynamic conditions based on hydrological observation data and underwater topographic data, using tidal current numerical models and wave numerical models; wherein, the hydrodynamic conditions include tidal current velocity, tidal current period, wave height and wave period;

[0124] Seabed sediment data is input into a trained sediment initiation model, and sediment initiation conditions are output; wherein, the sediment initiation conditions include initiation flow velocity and initiation wave height;

[0125] Risk assessment module: This module is used to classify the risk level of the engineering sea area based on underwater topographic data, hydrodynamic conditions, and sediment initiation conditions, and obtain the seabed erosion and deposition risk assessment results.

[0126] Example 3: This example provides a computer-readable storage medium storing a computer program / instruction thereon. When the computer program / instruction is executed by a processor, it implements the steps of the seabed erosion and deposition risk assessment method described in any one of Examples 1.

[0127] Example 4: This example provides a computer device / system / equipment, including:

[0128] Memory, used to store computer programs / instructions;

[0129] A processor is used to execute the computer program / instructions to implement the steps of the seabed erosion and sedimentation risk assessment method described in any one of Embodiments 1.

[0130] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for assessing seabed erosion and deposition risk, characterized in that, include: Acquire underwater topographic data, hydrological observation data, and seabed sediment data of the engineering area; Based on hydrological observation data and underwater topographic data, hydrodynamic conditions are calculated using tidal current numerical models and wave numerical models; wherein, the hydrodynamic conditions include tidal current velocity, tidal current period, wave height and wave period; Seabed sediment data is input into a trained sediment initiation model, and sediment initiation conditions are output; wherein, the sediment initiation conditions include initiation flow velocity and initiation wave height; Based on underwater topographic data, hydrodynamic conditions, and sediment initiation conditions, the risk level of the project area is classified, resulting in a risk assessment of seabed erosion and deposition.

2. The seabed erosion and deposition risk assessment method according to claim 1, characterized in that, The underwater topographic data includes underwater bank slope, erosion rate, and isobath movement speed. And / or, the hydrological observation data includes tidal level, current velocity, current direction, observed wave height, and wave number; And / or, the seabed sediment data includes the diameter of sediment particles.

3. The seabed erosion and deposition risk assessment method according to claim 1, characterized in that, The hydrodynamic conditions calculated based on hydrological observation data and underwater topographic data, using tidal current numerical models and wave numerical models, include: Underwater topographic data is used as the computational domain for the tidal current numerical model and the wave numerical model; Hydrological observation data will be used to validate numerical models of tidal currents and waves. Hydrodynamic conditions were calculated using the validated numerical models of tidal current and waves.

4. The seabed erosion and deposition risk assessment method according to claim 3, characterized in that, The governing equations of the power flow numerical model include: Continuity equation: ； Momentum equation in the X-axis direction: ； Y-axis momentum equation: ； Z-axis momentum equation: ； Where x, y, and z are the spatial coordinates along the X, Y, and Z axes, u is the flow velocity along the X-axis, v is the flow velocity along the Y-axis, w is the flow velocity along the Z-axis, t is time, and f is the Coriolis parameter. , The angular velocity of Earth's rotation. Latitude For reference density, For pressure, The vertical eddy viscosity coefficient is... The horizontal eddy viscosity coefficient. For the horizontal gradient operator, Where is the actual density, and g is the acceleration due to gravity.

5. The seabed erosion and deposition risk assessment method according to claim 3, characterized in that, The governing equations of the wave numerical model include: ； ； ； in, Where h is the vertical height of the actual water surface relative to the still water surface, and h is the water depth. Let g be the horizontal velocity vector representing the average water depth or reference water depth in the vertical direction, D be the gravitational acceleration, D be the vector including higher-order dispersion, dissipation, and bottom friction dissipation, and N be the wave action density spectrum. F is the energy spectral density, and f is the frequency. The wave direction is represented by x and y, which are the spatial coordinates along the X and Y axes, respectively, and t is the time interval. The natural angular frequency, For group velocity, Frequency translation speed, The directional translation velocity, The source and sink terms include wind energy input, wave-wave nonlinear interaction, dissipation, and low-friction dissipation. For vertical gradient operators; For vector gradient operators; This is the horizontal gradient operator in the X-axis direction.

6. The seabed erosion and deposition risk assessment method according to claim 1, characterized in that, The formula for calculating the starting flow rate is as follows: ； in, To start the flow rate, Where is the diameter of the sediment particles, and h is the water depth. For the specific density of water, The bulk density of silt; And / or, the formula for calculating the starting wave height is as follows: ； in, For the starting wave height, Where L is the wavelength, g is the acceleration due to gravity, and h is the water depth. For wave number, For the specific density of water, The bulk density of silt, The diameter of the sediment particles. for , is the adhesion coefficient.

7. The seabed erosion and deposition risk assessment method according to claim 2, characterized in that, The criteria for classifying risk levels include: If the underwater slope is greater than 1:30, the downcutting rate is greater than 0.2 m / a or the isobath movement speed is greater than 40 m / a, the period when the tidal current velocity is greater than the sediment initiation velocity is greater than 4 hours / tidal cycle, and the frequency when the wave height is greater than the initiation wave height is greater than 20%, it is judged as high risk. The underwater slope is 1:(30~50), the downcutting rate is 0.1~0.2 m / a or the isobath movement speed is 20~40 m / a, the period when the tidal current velocity is greater than the sediment initiation velocity is 2~4 hours / tidal cycle, and the wave height is greater than the initiation wave frequency is 5%~20%, which is judged as medium risk. If the underwater slope gradient is less than 1:50, the downcutting rate is less than 0.1 m / a or the isobath movement speed is less than 20 m / a, the period during which the tidal current velocity is greater than the sediment initiation velocity is less than 2 hours / tidal cycle, and the frequency of wave height being greater than the initiation wave height is less than 5%, it is judged as low risk.

8. A seabed erosion and siltation risk assessment device, characterized in that, include: Acquisition module: used to acquire underwater topographic data, hydrological observation data, and seabed sediment data of the engineering area; The calculation module is used to calculate hydrodynamic conditions based on hydrological observation data and underwater topographic data, using tidal current numerical models and wave numerical models; wherein, the hydrodynamic conditions include tidal current velocity, tidal current period, wave height and wave period; Seabed sediment data is input into a trained sediment initiation model, and sediment initiation conditions are output; wherein, the sediment initiation conditions include initiation flow velocity and initiation wave height; Risk assessment module: This module is used to classify the risk level of the engineering sea area based on underwater topographic data, hydrodynamic conditions, and sediment initiation conditions, and obtain the seabed erosion and deposition risk assessment results.

9. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that, When the computer program / instruction is executed by the processor, it implements the steps of the seabed erosion and deposition risk assessment method according to any one of claims 1 to 7.

10. A computer device / system / equipment, characterized in that, include: Memory, used to store computer programs / instructions; A processor for executing the computer program / instructions to implement the steps of the seabed erosion and sedimentation risk assessment method according to any one of claims 1 to 7.

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