Method for analyzing three-dimensional structure of submarine turbidity current based on underwater monitoring cable networking system

Abstract

The application provides a submarine turbidity current three-dimensional structure analysis method based on an underwater monitoring cable networking system, which comprises an underwater monitoring cable network (1) formed by a plurality of underwater monitoring cables (10) arranged along the direction of a submarine canyon, a comprehensive acquisition station (2), a marine wireless relay buoy (3), a satellite communication system (4) and a remote data receiving terminal (5). The technical scheme of the application provides a solution for the in-situ tracing of the form identification and dynamic process of the submarine turbidity current. Based on the system, a calculation method combining resistivity field inversion and motion field analysis is provided, three-dimensional form identification and vector motion determination of the submarine turbidity current process are realized, and the quantitative analysis of the submarine turbidity current structure from the geometric form to the dynamic behavior is realized.

Description

Technical Field

[0001] This invention relates to the field of marine disaster monitoring technology and computational analysis technology, and more specifically, to a method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system. Background Technology

[0002] Submarine turbidity currents are high-speed underwater currents carrying large amounts of sediment that occur in submarine canyons and slopes. They possess extremely strong erosion and transport capabilities, posing a devastating threat to marine engineering facilities such as submarine cables, pipelines, and platform foundations. Submarine turbidity currents have complex three-dimensional dynamic structures; understanding their internal velocity vector field and sediment concentration distribution evolution is crucial for accurately assessing their disaster-causing mechanisms and providing effective early warnings. Achieving in-situ, real-time, and transparent understanding of the three-dimensional spatial morphology and movement processes of turbidity currents has become a core challenge urgently needing to be addressed in the field of marine engineering geology and disaster monitoring.

[0003] Currently, research on submarine turbidity currents mainly relies on techniques such as acoustic-optical detection and in-situ monitoring. Acoustic techniques such as multibeam bathymetry can identify the extent of scouring and deposition caused by turbidity currents by comparing the terrain before and after their occurrence. However, this technique is only a post-event inference and cannot capture the dynamic occurrence and movement process of turbidity currents. While the marine bottom-mounted platform represented by patent CN109278962B has the advantages of long-term, continuous, and in-situ monitoring, and can obtain valuable time-series data during the occurrence of turbidity currents, it has fundamental limitations. First, it is deployed at a single point or locally in space, and cannot reconstruct the complete three-dimensional morphology of submarine turbidity currents, let alone analyze its three-dimensional velocity field. Second, its core sensors (such as acoustic Doppler current profilers and optical sensors) suffer severe signal attenuation and scattering in the core area of ​​turbidity currents containing high concentrations of sediment, resulting in the loss or distortion of key data and making it difficult to accurately reflect the true physical state inside the turbidity current.

[0004] The fundamental limitations of existing technologies can be summarized as follows: in terms of spatiotemporal resolution, they cannot simultaneously achieve large-scale three-dimensional coverage and fine capture of high-speed dynamic processes; in terms of monitoring capabilities, they struggle to effectively penetrate the core region of turbidity currents and obtain reliable internal information parameters; and in terms of analytical dimensions, they fail to achieve simultaneous calculation of the three-dimensional morphology of turbidity currents and their full-space motion characteristics. Ultimately, this results in the inability to form a dynamic understanding of the entire process of turbidity current events.

[0005] In summary, although existing technologies have made significant strides in monitoring submarine turbidity currents, there are still significant technological gaps in areas such as three-dimensional monitoring and dynamic process analysis. There is an urgent need in this field for a systematic solution that can overcome the limitations of single-point static monitoring and establish a complete technical system encompassing underwater networking, dynamic data acquisition, and simultaneous inversion of three-dimensional morphology and motion field. Ultimately, this system should enable three-dimensional, real-time, and quantitative analysis of submarine turbidity current transport information, providing core technical support for marine engineering safety and geological disaster prevention. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a three-dimensional structural analysis method for seabed turbidity currents based on an underwater monitoring cable network system. This method aims to solve the technical challenge of existing technologies being unable to perform in-situ tracing and dynamic structural analysis of high-speed dynamic processes such as seabed turbidity currents. Specifically, it proposes an in-situ monitoring system for the three-dimensional structure of seabed turbidity currents based on an underwater monitoring cable network system, providing a solution for morphological identification and in-situ tracing of dynamic processes in seabed turbidity currents. Based on this system, a calculation method integrating "resistivity field inversion" and "motion field analysis" is proposed to achieve three-dimensional morphological identification and vector motion determination of seabed turbidity current processes, realizing the quantitative analysis of seabed turbidity current structures from "geometric morphology" to "dynamic behavior."

[0007] The present invention is achieved through the following technical solution: a three-dimensional structural analysis method for seabed turbidity currents based on an underwater monitoring cable network system. The in-situ monitoring system based on the underwater monitoring cable network includes an underwater monitoring cable network formed by multiple underwater monitoring cables laid along the seabed canyon, an integrated acquisition station, a marine wireless relay buoy, a satellite communication system, and a remote data receiving terminal.

[0008] The underwater monitoring cable includes a flexible main cable, with rigid measuring sections evenly spaced on the flexible main cable. The beginning and end of the rigid measuring sections are vertically connected to the flexible main cable by an elastic connecting cable. A buoy is connected to the top of the underwater monitoring cable, and a counterweight anchor is connected to the bottom of the underwater monitoring cable through an acoustic release device. A main control compartment is also installed between the flexible main cable and the buoy assembly to store and send monitoring data to the integrated acquisition station.

[0009] The rigid measuring section includes an electrode assembly using the four-electrode Wenner method. A head-end positioning sensor and a tail-end positioning sensor are installed at both ends of the rigid measuring section, with the head end being the end closer to the counterweight anchor and the tail end being the end closer to the float. A temperature, salinity, and depth sensor is also installed on the rigid measuring section.

[0010] Specifically, the following steps are included:

[0011] Step S1, Three-dimensional network layout of the seabed canyon: based on the direction of the main axis of the seabed canyon. The axis is defined by the horizontal direction perpendicular to the canyon. The axis is oriented vertically upwards from the seabed. Axis, along axial direction with spacing Multiple underwater monitoring cables were deployed, their serial numbers are as follows: ,exist The axis is in the same water depth At the interval Multiple underwater monitoring cables were deployed, their serial numbers are as follows: Then the first The planar reference position of the cable is represented as Several rigid measuring sections are installed on each cable, and the section number along the z-axis is defined as follows: , No. The serial number of the positioning sensor at the front end of the short section is defined as follows: The tail-end positioning sensor serial number is defined as follows: The rigid measurement short section's structural length is defined as... The cable spacing between the center points of adjacent short sections is defined as And the height of the first short segment above the seabed is also... Therefore, the net space distance between adjacent short sections is By deploying an underwater monitoring cable network, a globally unique index is assigned to the resistivity measurement point of each short section. ;

[0012] Step S2, Monitoring Data Acquisition and Preprocessing: The initial apparent resistivity of the monitored data... Environmental compensation and inversion software processing is performed to obtain the resistivity of the environmental medium. The coordinates of the measurement points in the middle of the short section are calculated by combining spatial relationships. and overall spatial posture And based on the statistical fitting results, an empirical model of resistivity-sediment concentration was established;

[0013] Step S3, Reconstruction of the Three-Dimensional Resistivity Field of the Submarine Turbidity Current: Based on the results obtained in the above steps and indexed in the short section... Resistivity of the registered ambient medium and their corresponding coordinates Reconstruct a three-dimensional continuous resistivity field covering the entire monitoring network;

[0014] Step S4: Spatial distribution inversion of sediment concentration within the turbidity current: Based on the calculated three-dimensional spatial resistivity data of the submarine canyon water body, combined with the resistivity-sediment concentration empirical model, the spatiotemporal distribution of sediment concentration covering the entire monitoring network within the submarine canyon is inverted.

[0015] Step S5: Identification of the core volume of the submarine turbidity current: Based on the three-dimensional data volume of sediment concentration in the submarine canyon water obtained in the above steps. The three-dimensional turbidity core was accurately identified from the background water body using an intelligent image segmentation algorithm. ;

[0016] Step S6, Analysis of Submarine Turbidity Current Morphology: Based on Three-Dimensional Turbidity Current Core By analyzing the spatial distribution and gradient characteristics of the sediment concentration field inside the submarine turbidity current during its occurrence, we can quantify and analyze its geometric structure, identify and parameterize its key structural features.

[0017] Step S7, Analysis of the motion field of the submarine turbidity current: Based on the coordinate sequence obtained from each rigid measurement subsection (11) With attitude sequence The dynamic response of the short section under the impact of the submarine turbidity current was analyzed to characterize the dynamic process of the submarine turbidity current in three-dimensional space.

[0018] As a preferred option, step S2 specifically includes the following steps:

[0019] After the monitoring system is started, the index is The electrode assembly, temperature, salinity, depth sensor, head-end positioning sensor, and tail-end positioning sensor on the rigid measurement section synchronously acquire data according to a unified clock, and all data are timestamped. The electrode assembly uses the Winner method to measure the electrode voltage difference. With current and through device coefficient With system error correction factor After correction, the initial apparent resistivity is obtained:

[0020] ,

[0021] Then, the temperature was simultaneously measured using a temperature, salinity, and depth sensor. With salinity Environmental compensation is applied using the following formula:

[0022] ,

[0023] in, To correct to the reference temperature Compared with reference salinity apparent resistivity, For temperature coefficient, This is the salinity coefficient.

[0024] Finally, it was converted into the resistivity of the environmental medium using inversion software. Used for subsequent calculations;

[0025] Meanwhile, the positioning sensor at the front end of the rigid measurement section records the spatial coordinates. and attitude angle The tail-end positioning sensor records the spatial coordinates. and attitude angle First, calculate the measured distances between the front and rear positioning sensors:

[0026] ,

[0027] Then, through geometric relationships:

[0028] ,

[0029] Solve the Precise coordinates of the measurement point in the middle of the short section Simultaneously, by integrating the attitude angles of the beginning and end of the short segment, the overall spatial attitude of the short segment is obtained:

[0030] ;

[0031] For sediment concentration inversion, at least 30 sediment-containing water bodies with different sediment concentrations are configured, and the laboratory sediment concentration is measured. Resistivity of sediment-containing water in the laboratory And perform statistical fitting to determine the empirical coefficients. , , An empirical model of resistivity-sediment concentration was established, which is defined as follows: ,

[0032] in, The resistivity of the seawater within the submarine canyon is typically set to [value missing]. In the subsequent inversion calculation from the resistivity field to the sediment concentration field inside the turbidity flow, and Using the sediment concentration inside the turbidity flow to be inverted respectively and the resistivity of grid nodes To replace;

[0033] As a preferred option, step S3 specifically includes the following steps:

[0034] The water space of the monitoring system is placed in a three-dimensional rectangular coordinate system. The internal discretization is performed into regular rectangular mesh elements, whose dimensions in the three directions of the coordinate system are defined as ( The coordinates of the measurement points in the middle of each rigid measurement section (11) in the grid division. The grid nodes are set according to the principle that each measurement point can be located at the center of a grid cell, so that each measurement point can represent the electrical characteristics of its grid cell. The grid node coordinates are as follows: ,in For the grid index; for the current grid node to be interpolated, within its defined search range. within, share If there are several effective short-node measurement points, then the resistivity value of that node is determined by these... The grid nodes are calculated by weighted calculation of each point. The mathematical expression for resistivity is: ,

[0035] in It is to give the first Kriging weight coefficients for each measurement point; by traversing all grid nodes, a time-related parameter can be generated. Three-dimensional spatial resistivity data of the water body in the submarine canyon .

[0036] As a preferred option, step S4 specifically includes the following steps:

[0037] For each grid node At every moment resistivity value By directly substituting these values ​​into the empirical model described above and iterating through all grid nodes and time series, the coordinates can be calculated. In Sediment concentration at time , expressed as: .

[0038] As a preferred option, step S5 specifically includes the following steps:

[0039] Obtain typical sediment concentration levels in the marine environment within the submarine canyon when no submarine turbidity current event occurs. and its standard deviation Determine the sediment concentration threshold for submarine turbidity currents. , represented as:

[0040] ,

[0041] in The sensitivity coefficient, selected based on the historical intensity of submarine turbidity currents within the submarine canyon, is between 2.0 and 3.0, and all parameters in the concentration field that satisfy this value are considered. Grid nodes Mark as a candidate node;

[0042] At the same time, a sediment concentration tolerance is set. Its value is based on the maximum sediment concentration inside the submarine turbidity current within the submarine canyon. Compared with the background water sediment concentration The gradient is determined, expressed as: ;

[0043] Subsequently, a 3D region growing algorithm is executed, starting from the candidate node, checking the nodes within its 26-neighborhood. If the neighboring nodes satisfy... Furthermore, the difference between its sediment concentration value and the current candidate node is within the sediment concentration tolerance range. Then it will be merged into the core of the submarine turbidity current. The above operation is repeated, with each node acting as a new node, until no more nodes are added, ultimately generating a complete three-dimensional turbidity core. .

[0044] As a preferred option, step S6 specifically includes the following steps:

[0045] Step S6.1: Analyze the core of the submarine turbidity current. sediment concentration By performing differential calculations, its spatial gradient field is obtained. And further calculate its gradient magnitude field. The spatial variation rate of sediment concentration within a turbidity current is used to quantify the degree of drastic change in sediment concentration at a certain point in the core of the submarine turbidity current. Its high value area usually corresponds to the boundary between the submarine turbidity current and the marine environment or the abrupt change zone in the internal structure of the turbidity current.

[0046] Step S6.2: Identify and classify the morphology and structure of submarine turbidity currents. First, identify the head of the submarine turbidity current, which is the strong impact front as the current advances through the canyon. In three-dimensional space, the direction of the submarine turbidity current is initially determined based on the axis from shallow sea to deep sea within the canyon. The head is the core of the submarine turbidity current. The foremost part along the dominant migration direction strongly impacts the boundary surface, and within this boundary surface... Local maxima regions were identified as the head. ;main body Defined as satisfying and The set of grid cells, where Core of submarine turbidity currents The average sediment concentration of all grid nodes within the grid. Standard deviation The median of the gradient; the edge It is defined as satisfying and A set of grid cells;

[0047] Step S6.3: Based on the above division, further calculate the quantization parameters of each morphological unit, which are derived from the mesh units of each morphology. Accumulated; the volume of a mesh cell is represented as:

[0048] ,

[0049] The head volume of a submarine turbidity current can be expressed as:

[0050] ,

[0051] Similarly, the main volume can be expressed as

[0052] ,

[0053] The edge volume can be expressed as

[0054] ,

[0055] The volume of the core of the submarine turbidity current is then... , , The sum of the three.

[0056] As a preferred option, step S7 specifically includes the following steps:

[0057] Step S7.1, Motion Response Data Volume Construction: The data will be constructed from the index. The discrete rigid measurement segments (11) are asynchronously acquired and time-dependent. The relevant motion data is structured and integrated to construct a unified motion response data volume; based on the short segment rectangular coordinates obtained in the above steps... and the three-axis attitude angles describing the axial rotation of the short section Perform first-order difference calculation, that is, for each sampling interval The displacement vector is then:

[0058] ,

[0059] The instantaneous angular velocity vector is then:

[0060] ;

[0061] Finally, for each rigid measurement segment (11) at each time... Generate a complete motion record, which is represented as a data volume bound to a spatiotemporal index. ;

[0062] Step S7.2, Submarine Turbidity Current Impact Tracing: Based on the constructed motion response data volume, the movement trajectory of the submarine turbidity current head in the canyon is accurately captured by identifying abrupt changes in motion parameters; for each index... The angular velocity recorded by the rigid measuring section (11) Perform vector magnitude calculation when the short section First time using background values ​​of angular velocity without the influence of submarine turbidity currents Continuously exceeding the angular velocity threshold When the head of the turbidity flow arrives at the short section, the time is determined and recorded. Short-section angular velocity threshold Represented as: ,

[0063] in This represents the standard deviation of the background angular velocity values ​​obtained from historical data without the influence of submarine turbidity currents. The confidence coefficient, selected based on the monitoring accuracy requirements, is between 2.0 and 3.0; based on the time set recorded in all short sections. The three-dimensional propagation path of the turbidity current head in the submarine canyon was traced; on the migration path of the turbidity current head, any two short segments that were impacted by the submarine turbidity current one after the other were selected. and Record the corresponding moments of impact from the submarine turbidity current. and Its spatial distance The coordinates of the two at the instant of impact and The calculation yields the following result:

[0064] ;

[0065] Therefore, considering the time difference between their arrival times:

[0066] ,

[0067] Calculate the average propulsion velocity of the head of the submarine turbidity current in this short section:

[0068] .

[0069] Step S7.3, Three-dimensional distribution of submarine turbidity current movement direction: based on the rectangular coordinates measured at each short section during the submarine turbidity current movement stage. and displacement changes Data is used to quantitatively determine the overall direction of movement of submarine turbidity currents and analyze their spatial distribution characteristics; during periods of stable movement of submarine turbidity currents... Within this segment, the total net displacement vector is defined as:

[0070] ,

[0071] Its direction is: ,

[0072] The final coordinates of the seabed turbidity current in three-dimensional space Above, it is visualized in the form of 3D arrows, the direction of which represents... The direction, the length of the arrow and The magnitude of the displacement is proportional to the modulus, and at the same time, the unit vector in the direction of all short sections is calculated. vector average This characterizes the overall transport direction of the turbidity flow, and its calculation can be expressed as: ,in, The total number of short sections whose indices are involved in the calculation.

[0073] By employing the above technical solutions, this invention has the following beneficial effects compared to existing technologies:

[0074] (1) Realize three-dimensional monitoring of submarine turbidity currents. This invention overcomes the shortcomings of existing single-point monitoring technologies such as seabed bases in terms of insufficient spatial coverage by deploying a three-dimensional monitoring network in submarine canyons, and can simultaneously acquire information on the development process of turbidity currents in three-dimensional space.

[0075] (2) It has the ability to effectively identify the internal structure of high-concentration turbidity flow. This invention utilizes the characteristic that electrical signals are less affected by the turbidity of water to solve the problem of signal attenuation failure of acoustic and optical methods in the core area of ​​turbidity flow. It can directly obtain the resistivity data inside the turbidity flow and identify its three-dimensional structure and sediment concentration accordingly.

[0076] (3) Simultaneous analysis of the morphology and motion characteristics of turbidity flow. By fusing resistivity field and motion field data, this invention can simultaneously identify the geometric morphology of the head and core of turbidity flow and calculate its three-dimensional motion vector field, thereby achieving a complete quantitative analysis of the dynamic behavior of turbidity flow.

[0077] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0078] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0079] Figure 1 This is the in-situ monitoring system based on underwater monitoring cable networking as described in the embodiments of the present invention;

[0080] Figure 2 This is a schematic diagram of the underwater monitoring cable structure based on an electrical sensor according to an embodiment of the present invention;

[0081] Figure 3 Flowchart of the method for quantitative analysis of three-dimensional structure of submarine turbidity currents provided by the present invention;

[0082] Figure 4 A diagram illustrating the effect of three-dimensional spatial resistivity interpolation calculation of water bodies in submarine canyons provided by this invention.

[0083] Figure 5 This is a flowchart of the method for quantitative analysis of submarine turbidity current motion field provided by the present invention.

[0084] in, Figures 1 to 2 The correspondence between the reference numerals and components in the attached drawings is as follows:

[0085] 1: Underwater monitoring cable network; 2: Integrated data acquisition station; 3: Marine wireless relay buoy; 4: Satellite communication system; 5: Remote data receiving terminal; 10: Underwater monitoring cable; 11: Rigid measurement sub; 111: Electrode assembly; 112: Temperature, salinity, and depth sensor; 1131: Bow-end positioning sensor; 1132: Tail-end positioning sensor; 12: Elastic connecting cable; 13: Flexible main cable; 14: Acoustic release device; 15: Counterweight anchor; 16: Main control compartment; 17: Buoy. Detailed Implementation

[0086] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0087] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0088] The following is combined Figures 1 to 5 A method for analyzing the three-dimensional structure of seabed turbidity currents based on an underwater monitoring cable network system, according to an embodiment of the present invention, is described in detail.

[0089] like Figure 1 , Figure 2 As shown, this invention proposes a method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system. The method is characterized by an underwater monitoring cable network 1 formed by multiple underwater monitoring cables 10 laid along the seabed canyon, an integrated data acquisition station 2, a marine wireless relay buoy 3, a satellite communication system 4, and a remote data receiving terminal 5. During underwater operation, data collected by the underwater monitoring cable network 1 is aggregated at the integrated data acquisition station 2 on the seabed via wireless data transmission technology, and the data packets are transmitted wirelessly to the marine wireless relay buoy 3. The satellite communication system 4 enables rapid transmission of in-situ data to the remote data receiving terminal 5.

[0090] The underwater monitoring cable 10, as shown Figure 2 The system includes a flexible main cable 13, on which rigid measurement sections 11 are evenly spaced. To ensure the validity of the measurement data from the rigid measurement sections 11, the ends of the rigid measurement sections 11 are vertically connected to the flexible main cable 13 using elastic connecting cables 12. A buoy 17 is connected to the top of the underwater monitoring cable 10, and a counterweight anchor 15 is connected to the bottom of the underwater monitoring cable 10 via an acoustic release device 14. The underwater monitoring cable 10 relies on the counterweight anchor 15 and the buoy 17 to maintain vertical operation in the near-bottom environment of the seabed. To facilitate later retrieval or maintenance of the cable, the acoustic release device 14 can jettison the counterweight anchor 15 when necessary to allow the cable to float. A main control compartment 16 is also installed between the flexible main cable 13 and the buoy 17 to store and transmit monitoring data to the integrated data acquisition station 2.

[0091] The purpose of the rigid measuring sub 11 is to measure information about the structure of the seabed turbidity current, including an electrode group 111 using the four-electrode Wenner method, which can obtain the resistivity of the environmental medium corresponding to the middle position of the rigid measuring sub 11. At both ends of the rigid measuring sub 11, a bow positioning sensor 1131 and a tail positioning sensor 1132, which can accurately sense instantaneous attitude and motion, are respectively installed, with the bow end being the end closer to the counterweight anchor 15 and the tail end being the end closer to the buoy 17. In order to further calibrate the measured initial apparent resistivity, a temperature, salinity, and depth sensor 112 is also installed on the rigid measuring sub 11 to obtain environmental temperature, salinity, and depth data.

[0092] like Figure 3 Specifically, it includes the following steps:

[0093] Step S1: Three-dimensional network deployment in the submarine canyon: In the submarine canyon where turbidity currents are frequent, multiple underwater monitoring cables 10 are deployed in a three-dimensional network to form an underwater monitoring cable network 1. Specifically, the network is deployed along the main axis of the submarine canyon. The axis is defined by the horizontal direction perpendicular to the canyon. The axis is oriented vertically upwards from the seabed. Axis, along axial direction with spacing 10 underwater monitoring cables were deployed.

[0094] Its serial number is ,exist The axis is in the same water depth At the interval Ten underwater monitoring cables were deployed, their serial numbers being... Then the first The planar reference position of the cable is represented as Several rigid measuring sections 11 are installed on each cable, and the section numbers along the z-axis are defined as follows: , No. The serial number of the head-end positioning sensor 1131 on the short section is defined as follows: The tail-end positioning sensor (1132) is defined as follows: The rigid measurement short section (11) has a structural length defined as follows: The cable spacing between the center points of adjacent short sections is defined as And the height of the first short segment above the seabed is also... Therefore, the net space distance between adjacent short sections is When the Winner method is used for measurement, the four electrodes of the electrode group (111) are fixed at equal intervals on the short section, and the measured resistivity represents the electrical characteristics of the environmental medium at the middle position of the short section; through the deployment of the underwater monitoring cable network 1, a globally unique short section index is assigned to the resistivity measurement point of each short section. This ensures the system's ability to capture the three-dimensional spatial structure of turbidity;

[0095] Step S2, Monitoring Data Acquisition and Preprocessing:

[0096] After the monitoring system is started, the index is The electrode assembly 111, temperature, salinity, and depth sensor 112, the head-end positioning sensor 1131, and the tail-end positioning sensor 1132 on the rigid measuring section 11 synchronously acquire data according to a unified clock, and stamp all data with a unified timestamp. Electrode group 111 uses the Winner method to measure the electrode voltage difference. With current and through device coefficient With system error correction factor After correction, the initial apparent resistivity is obtained:

[0097] ,

[0098] The temperature was then simultaneously measured using the temperature-salinity depth sensor (112). With salinity Environmental compensation is applied using the following formula:

[0099] ,

[0100] in, To correct to the reference temperature Compared with reference salinity apparent resistivity, For temperature coefficient, This is the salinity coefficient.

[0101] Finally, it is converted into the resistivity of the ambient medium using inversion software (such as EarthImager, Res2D / 3Dinv, etc.). Used for subsequent calculations;

[0102] Meanwhile, the positioning sensor (1131) at the head end of the rigid measuring section (11) records the spatial coordinates. and attitude angle The tail-end positioning sensor (1132) records the spatial coordinates. and attitude angle First, calculate the measured distance between the front positioning sensor (1131) and the rear positioning sensor (1132):

[0103] ,

[0104] Then, through geometric relationships:

[0105] ,

[0106] Solve the Precise coordinates of the measurement point in the middle of the short section Simultaneously, by integrating the attitude angles of the beginning and end of the short segment, the overall spatial attitude of the short segment is obtained:

[0107] ;

[0108] For sediment concentration retrieval, on-site water and sediment samples are collected, combined with historical data on submarine turbidity currents, and at least 30 sediment-containing water bodies with different sediment concentrations are prepared in the laboratory to determine the laboratory sediment concentration. Resistivity of sediment-containing water in the laboratory And perform statistical fitting to determine the empirical coefficients. , , An empirical model of resistivity-sediment concentration was established, which is defined as follows: ,

[0109] in, The resistivity of the seawater in the study area can usually be set as . In the subsequent inversion calculation from the resistivity field to the sediment concentration field inside the turbidity flow, and Using the sediment concentration inside the turbidity flow to be inverted respectively and grid node resistivity To replace it.

[0110] Step S3, Reconstruction of the Three-Dimensional Resistivity Field of the Submarine Turbidity Current: Based on the results obtained in the above steps and indexed in the short section... Resistivity of precisely registered environmental medium and their corresponding coordinates Reconstruct a three-dimensional continuous resistivity field covering the entire monitoring network; and visualize the water body space of the monitoring system in a three-dimensional rectangular coordinate system. The internal discretization is performed into regular rectangular mesh elements, whose dimensions in the three directions of the coordinate system are defined as ( The coordinates of the measurement points in the middle of each rigid measurement section 11 in the grid division. The grid nodes are set according to the principle that each measurement point can be located at the center of a grid cell, so that each measurement point can represent the electrical characteristics of its grid cell. The grid node coordinates are as follows: ,in For the grid index; for the current grid node to be interpolated, within its defined search range. within, share If there are several effective short-node measurement points, then the resistivity value of that node is determined by these... The grid nodes are calculated by weighted calculation of each point. The mathematical expression for resistivity is: ,

[0111] in It is to give the first Kriging weight coefficients for each measurement point; by traversing all grid nodes, a time-related parameter can be generated. Three-dimensional spatial resistivity data of the water body in the submarine canyon Its computational effect in this patent is as follows: Figure 4 As shown.

[0112] Step S4: Spatial Distribution Inversion of Sediment Concentration within the Turbidity Current: Based on the calculated three-dimensional spatial resistivity data of the submarine canyon water, combined with the resistivity-sediment concentration empirical model, the spatiotemporal distribution of sediment concentration covering the entire monitoring network within the submarine canyon is inverted; for each grid node... At every moment resistivity value By directly substituting these values ​​into the empirical model described above and iterating through all grid nodes and time series, the coordinates can be calculated. In Sediment concentration at time , expressed as: .

[0113] Step S5: Identification of the core volume of the submarine turbidity current: Based on the three-dimensional data volume of sediment concentration in the submarine canyon water obtained in the above steps. The three-dimensional turbidity core was accurately identified from the background water body using an intelligent image segmentation algorithm. By combining historical data on submarine turbidity currents, typical sediment concentration levels in the marine environment of the submarine canyon when no submarine turbidity current events occurred were obtained. and its standard deviation Determine the sediment concentration threshold for submarine turbidity currents. , represented as:

[0114] ,

[0115] in The sensitivity coefficient, empirically selected based on the historical intensity of submarine turbidity currents in the target area, is between 2.0 and 3.0, and all parameters in the concentration field that satisfy this value are considered. Grid nodes Mark as a candidate node;

[0116] At the same time, a sediment concentration tolerance is set. Its value is based on the maximum sediment concentration within the submarine turbidity current in the target study area. Compared with the background water sediment concentration The gradient is determined, expressed as: ;

[0117] Subsequently, a 3D region growing algorithm is executed, starting from the candidate node, checking the nodes within its 26-neighborhood. If the neighboring nodes satisfy... Furthermore, the difference between its sediment concentration value and the current candidate node is within the sediment concentration tolerance range. Then it will be merged into the core of the submarine turbidity current. The above operation is repeated, with each node acting as a new node, until no more nodes are added, ultimately generating a complete three-dimensional turbidity core. .

[0118] Step S6, Analysis of Submarine Turbidity Current Morphology: Based on Three-Dimensional Turbidity Current Core By analyzing the spatial distribution and gradient characteristics of the sediment concentration field within submarine turbidity currents during their formation, the geometric structure is quantitatively analyzed, and key structural features are identified and parameterized. Specifically, the following steps are included:

[0119] Step S6.1: Analyze the core of the submarine turbidity current. sediment concentration By performing differential calculations, its spatial gradient field is obtained. And further calculate its gradient magnitude field. The spatial variation rate of sediment concentration within a turbidity current is used to quantify the degree of drastic change in sediment concentration at a certain point in the core of the submarine turbidity current. Its high value area usually corresponds to the boundary between the submarine turbidity current and the marine environment or the abrupt change zone in the internal structure of the turbidity current.

[0120] Step S6.2: Identify and classify the morphology and structure of submarine turbidity currents. First, identify the head of the submarine turbidity current, which is the strong impact front as the current advances through the canyon. In three-dimensional space, the direction of the submarine turbidity current is initially determined based on the axis from shallow sea to deep sea within the canyon. The head is the core of the submarine turbidity current. The foremost part along the dominant migration direction strongly impacts the boundary surface, and within this boundary surface... Local maxima regions were identified as the head. Subsequently, the main body and edges of the submarine turbidity current were finely divided based on the uniformity of sediment concentration and interfacial characteristics within the core; main body It is a stable region within the submarine turbidity current with the highest sediment concentration and the most concentrated material transport, defined as meeting the following criteria: and The set of grid cells, where Core of submarine turbidity currents The average sediment concentration of all grid nodes within the grid. Standard deviation The median of the gradient; the edge It is a dynamic transition zone where submarine turbidity currents and the surrounding marine environment undergo intense mixing, diffusion, and shearing, with sediment concentrations intermediate between the main seawater and the surrounding environment. Between the background water body and the concentration changes drastically, therefore, in this patent, it is defined as satisfying... and A set of grid cells;

[0121] Step S6.3: Based on the above division, further calculate the quantization parameters of each morphological unit, which are derived from the mesh units of each morphology. Accumulated; the volume of a mesh cell is represented as:

[0122] ,

[0123] The head volume of a submarine turbidity current can be expressed as:

[0124] ,

[0125] Similarly, the main volume can be expressed as

[0126] ,

[0127] The edge volume can be expressed as

[0128] ,

[0129] The volume of the core of the submarine turbidity current is then... , , The sum of the three;

[0130] Taking the main body of the submarine turbidity current as an example, in this patent, its distribution in three-dimensional space can be represented as follows: , , The aspect ratio of the submarine turbidity current used to describe the flatness or sharpness of the main body is then... .

[0131] Step S7, Analysis of the motion field of the submarine turbidity current: Based on the coordinate sequence obtained from each rigid measurement subsection (11) With attitude sequence This study analyzes the dynamic response of short sections under the impact of submarine turbidity currents to characterize the dynamic process of submarine turbidity currents in three-dimensional space; specifically, it includes the following steps:

[0132] Step S7.1, Motion Response Data Volume Construction: The data will be constructed from the index. The discrete rigid measurement segments (11) are asynchronously acquired and time-dependent. The relevant motion data is structured and integrated to construct a unified motion response data volume; based on the short segment rectangular coordinates obtained in the above steps... and the three-axis attitude angles describing the axial rotation of the short section Perform first-order difference calculation, that is, for each sampling interval The displacement vector is then:

[0133] ,

[0134] The instantaneous angular velocity vector is then:

[0135] ;

[0136] Finally, for each rigid measurement segment (11) at each time... Generate a complete motion record, which is represented as a data volume bound to a spatiotemporal index. ;

[0137] Step S7.2, Submarine Turbidity Current Impact Tracing: Based on the constructed motion response data volume, the migration trajectory of the submarine turbidity current head in the canyon is accurately captured by identifying abrupt changes in motion parameters; to characterize the severity of attitude changes of the sub-section under the impact of the submarine turbidity current, each index is... The angular velocity recorded by the rigid measuring section (11) Perform vector magnitude calculation when the short section First time using background values ​​of angular velocity without the influence of submarine turbidity currents Continuously exceeding the angular velocity threshold When the head of the turbidity flow arrives at the short section, the time is determined and recorded. Short-section angular velocity threshold Represented as: ,

[0138] in This represents the standard deviation of the background angular velocity values ​​obtained from historical data without the influence of submarine turbidity currents. The confidence coefficient, selected based on the monitoring accuracy requirements, is between 2.0 and 3.0; based on the time set recorded in all short sections. It can trace the three-dimensional propagation path of the turbidity current head in the submarine canyon; on the migration path of the turbidity current head, any two short segments that are impacted by the submarine turbidity current one after the other can be selected. and Record the corresponding moments of impact from the submarine turbidity current. and Its spatial distance The coordinates of the two at the instant of impact can be used to determine their positions. and The calculation yields the following result:

[0139] ;

[0140] Therefore, considering the time difference between their arrival times:

[0141] ,

[0142] Calculate the average propulsion velocity of the head of the submarine turbidity current in this short section:

[0143] .

[0144] Step S7.3, Three-dimensional distribution of submarine turbidity current movement direction: based on the rectangular coordinates measured at each short section during the submarine turbidity current movement stage. and displacement changes Data is used to quantitatively determine the overall direction of movement of submarine turbidity currents and analyze their spatial distribution characteristics; during periods of stable movement of submarine turbidity currents... Within this segment, the total net displacement vector is defined as:

[0145] ,

[0146] Its direction is: ,

[0147] The final coordinates of the seabed turbidity current in three-dimensional space Above, it is visualized in the form of 3D arrows, the direction of which represents... The direction, the length of the arrow and The magnitude of the displacement is proportional to the modulus, and at the same time, the unit vector in the direction of all short sections is calculated. vector average This characterizes the overall transport direction of the turbidity flow, and its calculation can be expressed as: ,in, The total number of short sections whose indices are involved in the calculation.

[0148] In the description of this invention, the term "a plurality of" refers to two or more. Unless otherwise explicitly defined, the terms "upper," "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0149] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0150] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for analyzing three-dimensional structure of a submarine turbidity current based on a network system of underwater monitoring cables, characterized by The in-situ monitoring system based on underwater monitoring cable network includes an underwater monitoring cable network (1) formed by underwater monitoring cables (10) laid along multiple coastal canyons, an integrated acquisition station (2), a marine wireless relay buoy (3), a satellite communication system (4), and a remote data receiving terminal (5). The underwater monitoring cable (10) includes a flexible main cable (13), with rigid measuring sections (11) evenly spaced on the flexible main cable (13). The ends of the rigid measuring sections (11) are vertically connected to the flexible main cable (13) by an elastic connecting cable (12). A float (17) is connected to the top of the underwater monitoring cable (10), and a counterweight anchor (15) is connected to the bottom of the underwater monitoring cable (10) through an acoustic release device (14). A main control compartment (16) is also installed between the flexible main cable (13) and the float (17) group to store and send monitoring data to the integrated acquisition station (2). The rigid measuring section (11) includes an electrode group (111) using the four-electrode Wenner method. A head-end positioning sensor (1131) and a tail-end positioning sensor (1132) are respectively installed at both ends of the rigid measuring section (11). The head end is the end closer to the counterweight anchor (15), and the tail end is the end closer to the float (17). A temperature, salinity and depth sensor (112) is also installed on the rigid measuring section (11). Specifically, the following steps are included: Step S1, Three-dimensional network layout of the seabed canyon: based on the direction of the main axis of the seabed canyon. The axis is defined by the horizontal direction perpendicular to the canyon. The axis is oriented vertically upwards from the seabed. Axis, along axial direction with spacing Multiple underwater monitoring cables (10) are laid, numbered i, i=1, 2, 3, ..., in The axis is in the same water depth At the interval Multiple underwater monitoring cables (10) are laid out, with serial numbers j, j=1, 2, 3, ..., then the number of the cables is... The planar reference position of the cable is represented as Several rigid measuring sections (11) are arranged on each cable. The section number along the z-axis is defined as k, k=1, 2, 3, ..., the number of the sections. The serial number of the head-end positioning sensor (1131) on the short section is defined as follows: The tail-end positioning sensor (1132) is defined as follows: The rigid measurement short section (11) has a structural length defined as follows: The cable spacing between the center points of adjacent short sections is defined as And the height of the first short segment above the seabed is also... Therefore, the net space distance between adjacent short sections is By deploying the underwater monitoring cable network (1), a globally unique short section index is assigned to the resistivity measurement point of each short section. ; Step S2, Monitoring Data Acquisition and Preprocessing: The acquired initial apparent resistivity... Environmental compensation and inversion software processing is performed to obtain the resistivity of the environmental medium. The coordinates of the measurement points in the middle of the short section are calculated by combining spatial relationships. and overall spatial posture And based on the statistical fitting results, an empirical model of resistivity-sediment concentration was established; Step S3, Reconstruction of the Three-Dimensional Resistivity Field of the Submarine Turbidity Current: Based on the results obtained in the above steps and indexed in the short section... Resistivity of the registered ambient medium and their corresponding coordinates Reconstruct a three-dimensional continuous resistivity field covering the entire monitoring network; Step S4: Spatial distribution inversion of sediment concentration within the turbidity current: Based on the calculated three-dimensional spatial resistivity data of the submarine canyon water body, combined with the resistivity-sediment concentration empirical model, the spatiotemporal distribution of sediment concentration covering the entire monitoring network within the submarine canyon is inverted. Step S5: Identification of the core volume of the submarine turbidity current: Based on the three-dimensional data volume of sediment concentration in the submarine canyon water obtained in the above steps. The three-dimensional turbidity core was accurately identified from the background water body using an intelligent image segmentation algorithm. ; Step S6, Analysis of Submarine Turbidity Current Morphology: Based on Three-Dimensional Turbidity Current Core By analyzing the spatial distribution and gradient characteristics of the sediment concentration field inside the submarine turbidity current during its occurrence, we can quantify and analyze its geometric structure, identify and parameterize its key structural features. Step S7, Analysis of the motion field of the submarine turbidity current: Based on the coordinate sequence obtained from each rigid measurement subsection (11) With attitude sequence The dynamic response of the short section under the impact of the submarine turbidity current was analyzed to characterize the dynamic process of the submarine turbidity current in three-dimensional space.

2. The method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system according to claim 1, characterized in that... Step S2 specifically includes the following steps: After the monitoring system is started, the index is The electrode assembly (111), temperature, salinity, and depth sensor (112), head-end positioning sensor (1131), and tail-end positioning sensor (1132) on the rigid measuring section (11) synchronously acquire data according to a unified clock and stamp all data with a unified timestamp. Electrode group (111) uses the Winner method to measure the electrode voltage difference. With current and through device coefficient With system error correction factor After correction, the initial apparent resistivity is obtained: ， The temperature was then simultaneously measured using the temperature-salinity depth sensor (112). With salinity Environmental compensation is applied using the following formula: ， in, To correct to the reference temperature Compared with reference salinity apparent resistivity, For temperature coefficient, This is the salinity coefficient. Finally, it was converted into the resistivity of the environmental medium using inversion software. Used for subsequent calculations; Meanwhile, the positioning sensor (1131) at the head end of the rigid measuring section (11) records the spatial coordinates. and attitude angle The tail-end positioning sensor (1132) records the spatial coordinates. and attitude angle First, calculate the measured distance between the front positioning sensor (1131) and the rear positioning sensor (1132): ， Then, through geometric relationships: ， Solve the Precise coordinates of the measurement point in the middle of the short section Simultaneously, by integrating the attitude angles of the beginning and end of the short segment, the overall spatial attitude of the short segment is obtained: ； For sediment concentration inversion, at least 30 sediment-containing water bodies with different sediment concentrations are configured, and the laboratory sediment concentration is measured. Resistivity of sediment-containing water in the laboratory And perform statistical fitting to determine the empirical coefficients. , , An empirical model of resistivity-sediment concentration was established, which is defined as follows: , in, The resistivity of the seawater within the submarine canyon is typically set to [value missing]. In the subsequent inversion calculation from the resistivity field to the sediment concentration field inside the turbidity flow, and Using the sediment concentration inside the turbidity flow to be inverted respectively and grid node resistivity To replace it.

3. The method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system according to claim 1, characterized in that... Step S3 specifically includes the following steps: The water space of the monitoring system is placed in a three-dimensional rectangular coordinate system. The internal discretization is performed into regular rectangular mesh elements, whose dimensions in the three directions of the coordinate system are defined as ( The coordinates of the measurement points in the middle of each rigid measurement section (11) in the grid division. The grid nodes are set according to the principle that each measurement point can be located at the center of a grid cell, so that each measurement point can represent the electrical characteristics of its grid cell. The grid node coordinates are as follows: ,in For the grid index; for the current grid node to be interpolated, within its defined search range. within, share If there are several effective short-node measurement points, then the resistivity value of that node is determined by these... The grid nodes are calculated by weighted calculation of each point. The mathematical expression for resistivity is: , in It is to give the first Kriging weight coefficients for each measurement point; by traversing all grid nodes, a time-related parameter can be generated. Three-dimensional spatial resistivity data of the water body in the submarine canyon .

4. The method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system according to claim 1, characterized in that... Step S4 specifically includes the following steps: For each grid node At every moment resistivity value By directly substituting these values ​​into the empirical model described above and iterating through all grid nodes and time series, the coordinates can be calculated. In Sediment concentration at time , expressed as: .

5. The method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system according to claim 1, characterized in that... Step S5 specifically includes the following steps: Obtain typical sediment concentration levels in the marine environment within the submarine canyon when no submarine turbidity current event occurs. and its standard deviation Determine the sediment concentration threshold for submarine turbidity currents. , represented as: ， in The sensitivity coefficient, selected based on historical submarine turbidity current intensities, is between 2.0 and 3.0, and all parameters in the concentration field that satisfy this value are considered. Grid nodes Mark as a candidate node; At the same time, a sediment concentration tolerance is set. Its value is based on the maximum sediment concentration inside the submarine turbidity current within the submarine canyon. Compared with the background water sediment concentration The gradient is determined, expressed as: ; Subsequently, a 3D region growing algorithm is executed, starting from the candidate node, checking the nodes within its 26-neighborhood. If the neighboring nodes satisfy... Furthermore, the difference between its sediment concentration value and the current candidate node is within the sediment concentration tolerance range. Then it will be merged into the core of the submarine turbidity current. The above operation is repeated, with each node acting as a new node, until no more nodes are added, ultimately generating a complete three-dimensional turbidity core. .

6. The method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system according to claim 1, characterized in that... Step S6 specifically includes the following steps: Step S6.1: Analyze the core of the submarine turbidity current. sediment concentration By performing differential calculations, its spatial gradient field is obtained. And further calculate its gradient magnitude field. The spatial variation rate of sediment concentration within a turbidity current is used to quantify the degree of drastic change in sediment concentration at a certain point in the core of the submarine turbidity current. Its high value area usually corresponds to the boundary between the submarine turbidity current and the marine environment or the abrupt change zone in the internal structure of the turbidity current. Step S6.2: Identify and classify the morphology and structure of submarine turbidity currents. First, identify the head of the submarine turbidity current, which is the strong impact front as the current advances through the canyon. In three-dimensional space, the direction of the submarine turbidity current is initially determined based on the axis from shallow sea to deep sea within the canyon. The head is the core of the submarine turbidity current. The foremost part along the dominant migration direction strongly impacts the boundary surface, and within this boundary surface... Local maxima regions were identified as the head. ;main body Defined as satisfying and The set of grid cells, where Core of submarine turbidity currents The average sediment concentration of all grid nodes within the grid. Standard deviation The median of the gradient; the edge It is defined as satisfying and A set of grid cells; Step S6.2: Based on the above division, further calculate the quantization parameters of each morphological unit, which are derived from the mesh units of each morphology. Accumulated; the volume of a mesh cell is represented as: ， The head volume of a submarine turbidity current can be expressed as: ， Similarly, the main volume can be expressed as ， The edge volume can be expressed as ， The volume of the core of the submarine turbidity current is then... , , The sum of the three.

7. The method for three-dimensional structural analysis of seabed turbidity currents based on an underwater monitoring cable network system according to claim 3, characterized in that... Step S7 specifically includes the following steps: Step S7.1, Motion Response Data Volume Construction: The data will be constructed from the index. The discrete rigid measurement segments (11) are asynchronously acquired and time-dependent. The relevant motion data is structured and integrated to construct a unified motion response data volume; based on the short segment rectangular coordinates obtained in the above steps... and the three-axis attitude angles describing the axial rotation of the short section Perform first-order difference calculation, that is, for each sampling interval The displacement vector is then: ， The instantaneous angular velocity vector is then: ； Finally, for each rigid measurement segment (11) at each time... Generate a complete motion record, which is represented as a data volume bound to a spatiotemporal index. ; Step S7.2, Submarine Turbidity Current Impact Tracing: Based on the constructed motion response data volume, the movement trajectory of the submarine turbidity current head in the canyon is accurately captured by identifying abrupt changes in motion parameters; for each index... The angular velocity recorded by the rigid measuring section (11) Perform vector magnitude calculation when the short section First time using background values ​​of angular velocity without the influence of submarine turbidity currents Continuously exceeding the angular velocity threshold When the head of the turbidity flow arrives at the short section, the time is determined and recorded. Short-section angular velocity threshold Represented as: , in This represents the standard deviation of the background angular velocity values ​​obtained from historical data without the influence of submarine turbidity currents. The confidence coefficient, selected based on the monitoring accuracy requirements, is between 2.0 and 3.0; based on the time set recorded in all short sections. The three-dimensional propagation path of the turbidity current head in the submarine canyon was traced; on the migration path of the turbidity current head, any two short segments that were impacted by the submarine turbidity current one after the other were selected. and Record the corresponding moments of impact from the submarine turbidity current. and Its spatial distance The coordinates of the two at the instant of impact and The calculation yields the following result: ； Therefore, considering the time difference between their arrival times: ， Calculate the average propulsion velocity of the head of the submarine turbidity current in this short section: ； Step S7.3, Three-dimensional distribution of submarine turbidity current movement direction: based on the rectangular coordinates measured at each short section during the submarine turbidity current movement stage. and displacement changes Data is used to quantitatively determine the overall direction of movement of submarine turbidity currents and analyze their spatial distribution characteristics; during periods of stable movement of submarine turbidity currents... Within this section, the total net displacement vector of the short section is defined as: ， Its direction is: Finally, the coordinates of the seabed turbidity current in three-dimensional space. Above, it is visualized in the form of 3D arrows, the direction of which represents... The direction, the length of the arrow and The magnitude of the displacement is proportional to the modulus, and at the same time, the unit vector in the direction of all short sections is calculated. vector average This is used to characterize the overall direction of turbidity flow.

Images