A water power model-based channel sedimentation prediction method

Abstract

This invention relates to the field of sediment prediction technology, specifically to a method for predicting sediment deposition in waterways based on a hydrodynamic model. The method includes the following steps: correcting the critical initiation velocity of sediments using the biomass, metabolic rate, and biofilm thickness of the microbial community to obtain a corrected critical initiation velocity; calculating the actual suspended sediment concentration in the waterway based on the corrected critical initiation velocity, combined with the turbulence intensity, propagation distance, and draft of the ship's wake; and calculating the sediment deposition volume in the waterway based on the suspended sediment concentration, combined with the cementation strength, water content, and organic matter decomposition rate of the surface sediments. This invention comprehensively considers ecological and navigation-related influencing factors and improves prediction accuracy in complex scenarios.

Description

Technical Field

[0001] This invention relates to the field of sediment prediction technology, specifically to a method for predicting sediment deposition in waterways based on a hydrodynamic model. Background Technology

[0002] In waterway maintenance and management, sediment deposition prediction is a crucial step in ensuring navigation capacity. Existing methods for predicting sediment deposition in waterways are mostly based on traditional hydrodynamic models, primarily considering conventional physical factors such as flow velocity, sediment particle size, and gravity settling, and achieving predictions by establishing a correlation between flow and sediment movement. However, existing technologies have significant limitations in complex waterway environments: they do not fully consider the implicit impacts of waterway ecosystems and navigation activities on sediment movement. For example, biofilms formed by microbial communities in eutrophic waterways alter sediment cohesion characteristics; unsteady wakes generated by low-speed ship traffic exacerbate local sediment suspension; and the cementation strength of surface sediments due to changes in water content affects sediment stability. The combined effect of these factors results in significant discrepancies between existing predictions and actual sedimentation conditions, making it difficult to meet the needs of precise maintenance.

[0003] Based on the above problems, there is an urgent need for a method to predict sediment deposition in waterways that can comprehensively consider ecological and navigation-related influencing factors and improve the prediction accuracy in complex scenarios. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a method for predicting sediment deposition in waterways based on a hydrodynamic model, comprising the following steps:

[0005] S1: The critical initiation velocity of sediments is corrected by the biomass, metabolic rate and biofilm thickness of the microbial community to obtain the corrected critical initiation velocity.

[0006] S2: Based on the corrected critical starting velocity, combined with the turbulence intensity, propagation distance and draft of the ship wake, calculate the actual suspended sediment concentration in the channel;

[0007] S3: Based on the suspended sediment concentration, combined with the cementation strength, water content and organic matter decomposition rate of the surface sediments of the riverbed, the amount of sediment deposition in the waterway is calculated.

[0008] Preferably, step S1 includes: obtaining the critical initiation velocity of sediments without biological disturbance, and correcting the critical initiation velocity of sediments without biological disturbance by combining the biomass, metabolic rate, biofilm thickness, average spacing between sediment particles, organic matter content in sediments, and total sediment concentration.

[0009] The biomass of the microbial community was obtained by collecting sediment samples from different monitoring points at the bottom of the channel and then culturing and counting them in the laboratory.

[0010] The metabolic rate was calculated by monitoring the oxygen consumption of sediment samples per unit time.

[0011] Biofilm thickness was obtained by observing and measuring the surface of sediments using microscopic imaging techniques.

[0012] More preferably, step S2 includes: obtaining the suspended sediment concentration and the actual water flow velocity in the channel when there is no ship interference; determining the velocity difference by combining the corrected critical starting velocity; and then correcting the basic value of suspended sediment concentration calculated from the velocity difference based on the turbulence intensity of the ship wake, the wake propagation distance, the ship draft, the ship speed, and the water flow velocity to obtain the actual suspended sediment concentration.

[0013] The turbulence intensity of the ship's wake is obtained in real time by turbulence sensors installed on both sides of the waterway; the wake propagation distance is calculated by the ship's position obtained by the ship positioning system and the position of the monitoring point.

[0014] More preferably, step S3 includes: obtaining the theoretical sedimentation amount without cementation, determining the concentration influence coefficient by combining the ratio of the actual suspended sediment concentration to the suspended sediment concentration without ship interference, and then correcting the basic value of sedimentation amount calculated by the concentration influence coefficient based on the cementation strength, water content, saturated water content of sediment, organic matter decomposition rate and time of the riverbed surface sediments to obtain the final sedimentation amount;

[0015] The cementation strength of the surface sediments in the riverbed was determined by indoor shear tests;

[0016] Moisture content was obtained by measuring the moisture content of sediment samples using the drying method;

[0017] The rate of organic matter decomposition was calculated by monitoring the change in organic matter content in sediment samples over time.

[0018] More preferably, the modified critical start-up flow rate is calculated using the modified critical start-up flow rate calculation formula:

[0019] ;

[0020] in, The corrected critical start-up flow rate; The critical initiation velocity without biological disturbance; The coefficient representing the influence of biological disturbance; Microbial biomass; Microbial metabolic rate; The thickness of the biofilm; The average spacing between sediment particles; The organic matter influence coefficient; This refers to the organic matter content in the sediment; This represents the total concentration of sediments.

[0021] More preferably, the actual suspended sediment concentration is calculated using the suspended sediment concentration formula:

[0022] ;

[0023] in, This represents the actual concentration of suspended sediment. The concentration of suspended sediment when there is no ship interference; This refers to the actual water flow velocity in the waterway; The corrected critical start-up flow rate; This is the flow velocity sensitivity coefficient; The wake effect coefficient; The intensity of turbulence in the ship's wake; This refers to the wake propagation distance. This is the wake attenuation coefficient; The ship's draft; The coefficient representing the influence of ship speed; For ship speed; The velocity is the water flow velocity.

[0024] More preferably, the final amount of siltation is calculated using the following formula:

[0025] ;

[0026] in, This represents the final amount of silt deposited. This represents the theoretical amount of sediment accumulation without cementing. This represents the actual concentration of suspended sediment. The concentration of suspended sediment when there is no ship interference; This is the concentration sensitivity coefficient; This is the bonding strength coefficient; The cementation strength of the surface sediments in the riverbed; The water content of the sediment; This represents the saturated water content of the sediment. The coefficient of organic matter decomposition; The rate of organic matter decomposition; For time.

[0027] In a further preferred embodiment, when obtaining the biomass of the microbial community, at least five different monitoring points are selected at the bottom of the channel, and three sediment samples are collected from each monitoring point. The collected samples are cultured and counted in the laboratory using the plate counting method. After removing outliers, the average value is taken as the microbial biomass of the monitoring point. Then, the weighted average of the microbial biomass of all monitoring points is taken as the biomass of the microbial community in the channel. The weight of the weighted average is determined according to the channel width and water flow velocity at the location of each monitoring point. The larger the channel width and the slower the water flow velocity, the greater the weight of the monitoring point.

[0028] In a further preferred embodiment, when acquiring the turbulence intensity of the ship's wake, three turbulence sensors are installed on each side of the ship's navigation path. The sensors are installed at a height of 1 / 2 of the channel depth, and the sampling frequency of the sensors is set to 100Hz. Turbulence signals are continuously collected for 2 minutes as the ship passes by. The collected signals are subjected to Fourier transform to obtain the frequency spectrum, and the signal energy value in the frequency range of 0.5-5Hz is extracted. The ratio of this energy value to the background turbulence energy value before the ship passes is taken as the turbulence intensity of the ship's wake.

[0029] Further preferred, sediment samples were collected from the surface layer of the riverbed at a depth of 0-20 cm. The samples were prepared into cylindrical specimens with a diameter of 5 cm and a height of 10 cm. A triaxial shear test was conducted on the specimens. During the test, the confining pressure was maintained at 100 kPa and the shear rate was 0.5 mm / min. The test was stopped when the shear displacement reached 15% of the specimen height. The maximum shear stress during the shear process was taken as the cementation strength of the surface sediments of the riverbed.

[0030] Technical effects:

[0031] This invention incorporates biological disturbance, ship wake, and sediment cementation strength into the prediction through a three-level progressive calculation logic, which is its innovative technical point. It solves the problem of large prediction deviations in existing methods that fail to consider these factors, accurately capturing the impact of biofilm, wake, and cementation strength on siltation, improving prediction accuracy in complex waterway environments, and providing a reliable basis for waterway maintenance. Attached Figure Description

[0032] Figure 1 This is a flowchart of a method for predicting sediment deposition in waterways based on a hydrodynamic model, as proposed in this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] Traditional methods for predicting sediment deposition have the following technical problems: existing methods mainly rely on conventional parameters such as water flow velocity and sediment particle size, without considering the influence of microbial activity on sediment characteristics, resulting in large deviations in the calculation of critical starting flow velocity; they ignore the unsteady turbulent effects of ship wakes, and cannot accurately reflect the sediment suspension patterns in navigation scenarios; they do not incorporate the dynamic changes in the cementation strength of riverbed sediments, and lack a basis for judging sedimentation stability, making it difficult for the overall prediction accuracy to meet practical needs in complex waterway environments.

[0035] Based on this, this embodiment provides a method for predicting sediment deposition in waterways based on a hydrodynamic model, including the following steps:

[0036] S1: First, the critical initiation velocity of the sediment is corrected by the biomass, metabolic rate and biofilm thickness of the microbial community to obtain the corrected critical initiation velocity.

[0037] S2: Based on the corrected critical starting velocity, combined with the turbulence intensity, propagation distance and draft of the ship wake, calculate the actual suspended sediment concentration in the channel.

[0038] S3: Finally, based on the suspended sediment concentration, combined with the cementation strength, water content and organic matter decomposition rate of the surface sediments of the riverbed, the amount of sediment deposition in the waterway is calculated.

[0039] This scheme incorporates multi-dimensional factors such as biological, ship, and sediment characteristics into the prediction model through a three-level progressive calculation logic. It solves the prediction bias problem caused by traditional methods that rely on only a single water flow parameter, and achieves accurate prediction of siltation in complex waterway environments, providing reliable data support for the formulation of waterway maintenance plans.

[0040] Traditional techniques for calculating the critical initiation velocity of sediments do not consider the influence of biological activity, resulting in the following technical problems: relying solely on physical parameters such as sediment particle size and specific gravity cannot reflect the enhancing effect of biofilm formed by microbial communities on sediment cohesion, leading to a significant deviation between the theoretical and actual values ​​of the critical initiation velocity in eutrophic waterways, which in turn affects the subsequent judgment of sediment suspension patterns; at the same time, the lack of standardized methods for obtaining biological parameters makes it difficult to guarantee the reliability and repeatability of the correction process.

[0041] Based on this, step S1 includes: obtaining the critical initiation velocity of sediments without biological disturbance, and correcting the critical initiation velocity of sediments using the biomass, metabolic rate, and biofilm thickness of the microbial community. Specifically, this includes: obtaining the critical initiation velocity of sediments without biological disturbance, and correcting the critical initiation velocity of sediments without biological disturbance by combining the biomass, metabolic rate, biofilm thickness, average spacing between sediment particles, organic matter content in the sediment, and total sediment concentration; wherein, the biomass of the microbial community is obtained by collecting sediment samples at different monitoring points at the bottom of the channel and counting them in the laboratory; the metabolic rate is calculated by monitoring the oxygen consumption of sediment samples per unit time; and the biofilm thickness is obtained by observing and measuring the sediment surface using microscopic imaging technology.

[0042] This scheme introduces a biological disturbance correction mechanism, filling the gap in the consideration of biological factors in traditional hydrodynamic models. Through a standardized biological parameter acquisition process, the scientific nature and operability of the correction process are ensured, making the calculation of the critical start-up velocity more consistent with the actual waterway environment and providing accurate basic parameters for subsequent suspended concentration calculations.

[0043] Traditional analyses of the impact of ship wakes on sediment suspension suffer from the following technical problems: using only the average ship speed as an influencing factor fails to quantify the spatiotemporal distribution characteristics of wake turbulence intensity, resulting in insufficient accuracy in predicting sediment suspension concentration in densely trafficked areas; simultaneously, the lack of a correlation mechanism with the critical initiation velocity after bio-disturbance correction makes it difficult to reflect the actual suspension effect after wake turbulence breaks through biofilm constraints; furthermore, the methods for collecting wake parameters lack standardization, making it difficult to guarantee data reliability.

[0044] Based on this, the steps of S2 include: obtaining the suspended sediment concentration and the actual water flow velocity in the channel when there is no ship interference; calculating the actual suspended sediment concentration in the channel based on the corrected critical starting velocity, combined with the turbulence intensity, propagation distance, and ship draft of the ship wake; specifically, obtaining the suspended sediment concentration and the actual water flow velocity in the channel when there is no ship interference; determining the velocity difference based on the corrected critical starting velocity; and then correcting the basic value of suspended sediment concentration calculated from the velocity difference based on the turbulence intensity, wake propagation distance, ship draft, ship speed, and water flow velocity to obtain the actual suspended sediment concentration; wherein, the turbulence intensity of the ship wake is obtained by real-time monitoring through turbulence sensors installed on both sides of the channel; and the wake propagation distance is calculated by the ship position obtained by the ship positioning system and the monitoring point position.

[0045] This scheme establishes a linkage analysis mechanism between ship wake and biological disturbance. Through standardized wake parameter acquisition methods, it achieves dynamic and accurate calculation of suspended sediment concentration, solving the problem of insufficient consideration of navigation interference in traditional methods. It can accurately capture the peak value of suspended sediment when ships pass by, providing support for the refined prediction of waterway sediment deposition.

[0046] Traditional methods for calculating sediment deposition have the following technical problems during the sediment deposition stage: they rely solely on suspended sediment concentration and settling velocity, failing to consider the impact of the cementation strength of surface sediments on sediment redeposition stability. This leads to significant discrepancies between predicted and actual deposition values ​​in waterways where water content and organic matter content vary considerably. Furthermore, the lack of consideration for dynamic factors such as organic matter decomposition prevents the reflection of stability changes during long-term deposition. In addition, the lack of standardized methods for obtaining parameters such as cementation strength affects the reliability of the calculation results.

[0047] Based on this, step S3 includes: obtaining the theoretical sedimentation volume without cementation; calculating the sedimentation volume in the channel based on the suspended sediment concentration, combined with the cementation strength, water content, and organic matter decomposition rate of the surface sediments; specifically, obtaining the theoretical sedimentation volume without cementation; determining the concentration influence coefficient based on the ratio of the actual suspended sediment concentration to the suspended sediment concentration without ship interference; and then correcting the basic value of sedimentation volume calculated by the concentration influence coefficient based on the cementation strength, water content, saturated water content of the sediments, organic matter decomposition rate, and time of the surface sediments to obtain the final sedimentation volume; wherein, the cementation strength of the surface sediments is determined by indoor shear tests; the water content is obtained by measuring the moisture content of the sediment samples using the drying method; and the organic matter decomposition rate is calculated by monitoring the change in organic matter content in the sediment samples over time.

[0048] This scheme introduces a cementation strength regulation mechanism, incorporates the physicochemical properties of sediments into the sedimentation calculation model, and ensures the scientific nature and repeatability of the calculation process through a standardized parameter acquisition process. It can accurately reflect the actual situation of sedimentation under different waterway environments, especially in areas with significant seasonal changes in water content, where the prediction accuracy is effectively improved.

[0049] Traditional techniques lack quantitative models for calculating critical start-up flow rates after biological disturbance correction, resulting in the following technical problems: Qualitative descriptions of the impact of biological factors fail to accurately reflect the quantitative relationship between parameters such as biomass and metabolic rate and the critical start-up flow rate, leading to insufficient accuracy and reliability of the correction results; Furthermore, the synergistic effects among various influencing factors are not fully considered, making it difficult to reflect the comprehensive enhancing effect of parameters such as biofilm thickness and organic matter content on cohesion, thus affecting the scientific rigor and traceability of the correction process.

[0050] Based on this, the corrected critical start-up flow rate is calculated using the following formula:

[0051] ;

[0052] in, The corrected critical start-up flow rate; The critical initiation velocity without biological disturbance; The coefficient representing the influence of biological disturbance; Microbial biomass; Microbial metabolic rate; The thickness of the biofilm; The average spacing between sediment particles; The organic matter influence coefficient; This refers to the organic matter content in the sediment; This represents the total concentration of sediments.

[0053] in, The revised critical initiation velocity, obtained by comprehensively considering various biological disturbance factors, is used to more accurately reflect the water flow velocity at which sediment initiation begins in actual waterways. It uses the same units as the critical initiation velocity calculated in the traditional method to facilitate connection and comparison in subsequent hydrodynamic calculations. This is the critical initiation velocity under undisturbed biological conditions. It is calculated based on traditional hydrodynamic theory, considering only the physical properties of sediments, and serves as the fundamental value for the entire modified formula. In practical applications, it can be calculated using classic hydrodynamic models combined with basic data such as local channel topography and current flow.

[0054] The bio-disturbance influence coefficient is obtained through fitting extensive experimental and actual monitoring data. It is used to quantify the comprehensive influence of biological factors such as microbial biomass, metabolic rate, and biofilm thickness on the critical start-up velocity. Its value range was determined through long-term research and multiple sets of comparative experiments. Under different waterway ecological environments, this coefficient may be adjusted, but it generally varies within a predictable range to ensure the accuracy and applicability of the formula in different scenarios.

[0055] Representing microbial biomass, it is obtained by collecting sediment samples from different monitoring points at the bottom of the waterway and then culturing and counting them in the laboratory. In practice, the selection of sampling points follows certain distribution rules to ensure a comprehensive reflection of the distribution of microorganisms within the waterway.

[0056] For example, sampling points are set up in different water depth areas, different water flow speed areas, and different geological conditions areas of the waterway. Then, multiple samples are collected from each sampling point, and multiple incubation and counting are performed. The average value is taken as the microbial biomass of that point. Finally, the microbial biomass data of the entire waterway is obtained by weighted averaging and other methods, thereby ensuring the accuracy and representativeness of the data.

[0057] The microbial metabolic rate is calculated by monitoring the oxygen consumption of sediment samples per unit time. During the experiment, collected sediment samples are placed in a specific culture device to simulate the actual environmental conditions within the waterway. High-precision oxygen sensors monitor oxygen consumption, and the oxygen consumption is converted into the microbial metabolic rate based on relevant chemical reaction equations and conversion factors. The experimental setup and operating procedures are standardized to ensure accurate and comparable results for different researchers conducting experiments at different times.

[0058] This refers to the thickness of the biofilm, which is obtained by observing and measuring the surface of the sediment using microscopic imaging techniques. In actual measurement, the sediment sample is first sliced, and then the slices are photographed using a high-resolution microscope. The thickness of the biofilm is then measured using image analysis software.

[0059] To reduce measurement errors, multiple slices of each sample are measured, and the average value is taken as the biofilm thickness for that sample. Throughout the measurement process in the waterway, sediment samples from multiple locations are measured to reflect the spatial distribution differences in biofilm thickness.

[0060] The average spacing between sediment particles is a parameter calculated based on the physical properties of sediments, such as particle size distribution. It reflects the spatial relationship between sediment particles. In practical applications, physical analyses such as sieving of sediment samples are performed to determine the proportion of particles of different sizes, and then the average spacing between sediment particles is calculated using relevant mathematical models. This parameter is crucial for understanding the adhesion and interaction mechanisms of biofilms between sediment particles, as the presence of biofilms alters the cohesion between sediment particles, thereby affecting the critical initiation velocity. The organic matter influence coefficient and the biological disturbance influence coefficient are respectively. Similarly, this value, determined through experiments and data analysis, is used to quantify the impact of organic matter content in sediments on the critical initiation velocity. Its value is also adjusted according to different waterway environments to ensure the accuracy of the formula.

[0061] The source and content of organic matter in sediments within waterways vary depending on geographical region and degree of water pollution. Adjustments can be made to address these variations. Values ​​allow formulas to better adapt to these changes.

[0062] The organic matter content in sediments is obtained through chemical analysis of sediment samples. In the laboratory, standard chemical analysis methods such as the agitation method are used. The sediment sample is first dried to remove moisture, then agitated at a high temperature. The organic matter content is calculated by measuring the change in mass of the sample before and after agitation. This method has high accuracy and repeatability, providing reliable organic matter content data for formulas.

[0063] Total sediment concentration (TSC) is calculated by measuring the mass and volume of a sediment sample to determine the total mass of sediment per unit volume. During the measurement process, the sample is precisely weighed and its volume is measured to ensure data accuracy. This parameter, along with organic matter content, is used to calculate the proportion of organic matter in the entire sediment, thus reflecting the degree of influence of organic matter on sediment properties.

[0064] This formula establishes a quantitative relationship between bio-disturbance parameters and critical initiation velocity. It reflects the influence of biofilm thickness and organic matter content through exponential functions and proportional relationships, respectively, and achieves accurate correction under the synergistic effect of multiple factors. This upgrades the calculation of critical initiation velocity from qualitative description to quantitative analysis, providing accurate basic parameters for subsequent prediction of sediment suspension and deposition. At the same time, the parameters of the formula are clearly defined, making it easy for those skilled in the art to understand and apply.

[0065] Traditional techniques lack scientific quantitative models for calculating suspended sediment concentration under the influence of ship wakes, resulting in the following technical problems: estimations rely solely on empirical formulas, failing to consider the spatiotemporal attenuation characteristics of ship wake turbulence intensity, thus failing to accurately reflect the differences in wake interference between ships with different drafts and speeds; furthermore, the lack of correlation with the critical initiation velocity after bio-disturbance correction makes it difficult for calculation results to reflect the dynamic suspension process of biofilm binding and wake breakthrough in actual waterways; additionally, the definitions of formula parameters are vague, and the logic of the effects of various influencing factors is unclear, hindering understanding and application by those skilled in the art.

[0066] Based on this, the actual suspended sediment concentration is calculated using the following formula:

[0067] ;

[0068] in, This represents the actual concentration of suspended sediment. The concentration of suspended sediment when there is no ship interference; This refers to the actual water flow velocity in the waterway; The corrected critical start-up flow rate; This is the flow velocity sensitivity coefficient; The wake effect coefficient; The intensity of turbulence in the ship's wake; This refers to the wake propagation distance. This is the wake attenuation coefficient; The ship's draft; The coefficient representing the influence of ship speed; For ship speed; The velocity is the water flow velocity.

[0069] As the actual suspended sediment concentration, it is a value that truly reflects the suspended sediment concentration in the waterway, obtained after considering various factors such as the influence of ship wakes, the difference between water flow velocity and the corrected critical starting velocity. In waterway management and maintenance, this parameter is of great significance for assessing the risk of sediment deposition and predicting changes in waterway depth. This represents the suspended sediment concentration under conditions of no ship interference. It is calculated using a traditional sediment transport model based on local water flow, sediment characteristics, and riverbed topography, without considering the impact of ship traffic. This value can serve as a baseline reference for analyzing the additional impact of ship traffic on suspended sediment concentration.

[0070] The actual water flow velocity in the waterway is obtained through real-time monitoring using equipment such as current meters installed within the waterway. In practical applications, multiple current velocity monitoring points are set up at different locations and water depths along the waterway to obtain the distribution of water flow velocity across the entire waterway cross-section. The data from these monitoring points is transmitted in real-time to a data processing center via a data transmission system. After data fusion and analysis, accurate data on the actual water flow velocity in the waterway is obtained.

[0071] The critical starting velocity formula has been explained in detail above, and it is used here in conjunction with the actual water flow velocity in the channel. A comparison was made to calculate the effect of the difference in water flow velocity on the concentration of suspended sediment.

[0072] The velocity sensitivity coefficient was determined using a combination of statistical analysis and numerical simulation based on a large amount of experimental and actual monitoring data.

[0073] It reflects the sensitivity of suspended sediment concentration to differences in water flow velocity. This coefficient varies depending on different channel topography, sediment characteristics, and water flow conditions. For example, in narrow channels, changes in water flow velocity may have a more significant impact on suspended sediment concentration. The value will be relatively large; while in wide and calm waterways, The value is relatively small. The wake influence coefficient, similar to the velocity sensitivity coefficient, is also determined based on experimental and actual monitoring data. It is used to quantify the degree of influence of ship wakes on suspended sediment concentration. Ship wakes have complex flow field structures and turbulent characteristics, and the impact of ship wakes on sediment suspension varies depending on the type of ship, draft, and speed.

[0074] By monitoring and analyzing a large number of different ship navigation conditions, and combining this with hydrodynamic experiments, the wake influence coefficients under different scenarios were determined. This ensures that the formula accurately reflects the effect of ship wake on suspended sediment concentration. The intensity of ship wake turbulence is measured in real time by turbulence sensors installed on both sides of the waterway. High-precision, high-sensitivity turbulence sensors are selected to accurately capture turbulence signals in the ship wake. The sensor installation locations are carefully designed, typically in areas where the ship wake has a significant impact, and multiple sensors are placed at different heights and distances to obtain the spatial distribution of wake turbulence intensity.

[0075] The signals collected by the sensors are amplified, filtered, and then transmitted to the data acquisition system for analysis and calculation to obtain accurate data on the intensity of ship wake turbulence. The wake propagation distance is expressed in units of 1 / 2 oz. It is calculated by using the ship's position obtained through the ship positioning system and the position of the monitoring point.

[0076] In practice, the ship positioning system records the ship's navigation trajectory and position information in real time, and sets up multiple fixed monitoring points in the waterway to record their position coordinates.

[0077] By calculating the distance between the ship's position and the monitoring point, the distance the wake travels to that monitoring point can be determined. As the ship sails, the wake gradually weakens during propagation; therefore, the wake propagation distance is an important factor affecting the concentration of suspended sediment. The wake attenuation coefficient is determined based on extensive experimental and observational data, considering the attenuation characteristics of wakes from different types of ships. It reflects the gradual weakening of the ship's wake intensity during propagation; different waterway conditions and ship parameters all affect the wake attenuation coefficient.

[0078] For example, in shallower waterways, the wake is more easily weakened by the riverbed. The value will be relatively large; while in deep and wide channels, the wake decays relatively slowly. The value is relatively small. Draft, measured in meters (m), is a crucial parameter of a ship and is known during its design and operation. The draft affects the flow field structure and intensity of the ship's wake, thus influencing the suspension of sediment. A greater draft can result in a stronger disturbance of sediment at the bottom by the ship's wake, therefore it is considered an important parameter in the formula. The ship speed influence coefficient, determined through experiments and data analysis, is used to quantify the impact of ship speed on suspended sediment concentration. Changes in ship speed alter characteristics such as wake velocity and turbulence intensity, thus affecting suspended sediment concentration differently. By monitoring and analyzing ship wake and suspended sediment concentration at different speeds, a quantitative relationship between ship speed and suspended sediment concentration was established, and the ship speed influence coefficient was determined. This is to ensure that the formula accurately reflects this effect. This refers to the ship's speed, measured in m / s, and is obtained through the ship's own speed measuring equipment. During navigation, the speed measuring equipment monitors the ship's speed in real time and transmits the data to the ship's control system and related monitoring platforms. This refers to the water flow velocity, which is different from the actual water flow velocity in the channel mentioned earlier. Correspondingly, the unit is also m / s, which reflects the influence of water flow on ship wake and suspended sediment movement. The ratio of ship speed to water flow speed affects the propagation characteristics of ship wake in the water flow and the suspension effect on sediment, and therefore is considered as an important parameter combination in the formula.

[0079] This formula constructs a three-level calculation logic for basic velocity difference, wake attenuation, and speed ratio. It quantifies the impact of wake propagation distance and ship draft by using exponential functions and attenuation terms, respectively, and realizes the organic linkage between ship wake and biological disturbance correction parameters, thus upgrading the calculation of suspended sediment concentration from empirical estimation to precise quantitative analysis.

[0080] The parameters in the formula are clearly defined and have clear physical meanings. They can not only accurately capture the suspension patterns of sediment under different ship navigation scenarios, but also provide reliable basic data for subsequent sedimentation calculation. This makes it easy for those skilled in the art to adjust the parameters according to actual waterway conditions, and has strong practicality and operability.

[0081] Traditional techniques lack standardized methods for obtaining microbial community biomass, resulting in the following technical problems: arbitrary selection of sampling points without considering the differences in biological distribution in different areas of the waterway, leading to insufficient representativeness of biomass data; small sample size and lack of outlier handling, resulting in poor data stability and reliability; and failure to set weights based on the waterway characteristics of monitoring points, failing to reflect the degree of impact of biological disturbance in different areas on the overall waterway, thus affecting the accuracy of subsequent critical start-up velocity correction.

[0082] Based on this, when obtaining the biomass of the microbial community, at least five different monitoring points were selected at the bottom of the channel. Three sediment samples were collected from each monitoring point. The collected samples were cultured and counted in the laboratory using the plate counting method. After removing outliers, the average value was taken as the microbial biomass of that monitoring point. Then, the weighted average of the microbial biomass of all monitoring points was taken as the biomass of the microbial community in the channel. The weight of the weighted average was determined according to the channel width and water flow velocity at the location of each monitoring point. The larger the channel width and the slower the water flow velocity, the greater the weight of the monitoring point.

[0083] This scheme addresses the issues of insufficient representativeness and poor data stability in traditional sampling methods by standardizing the number of sampling points, sample size, and data processing procedures. The introduction of a weighted calculation mechanism based on channel width and water flow velocity enables biomass data to more accurately reflect the actual impact of biological disturbance in different areas, avoiding the problem of local biases masking overall patterns caused by simple averaging. The standardized operating procedures not only ensure data reliability and repeatability but also provide high-quality basic parameters for the subsequent precise correction of critical initiation flow velocities, transforming the biological disturbance correction mechanism from a theoretical concept into an operational technical solution.

[0084] Traditional methods for obtaining the intensity of ship wake turbulence lack uniformity and scientific rigor, resulting in the following technical problems: unreasonable sensor placement, making it impossible to accurately capture turbulence signals in the core wake region; excessively low sampling frequency, easily missing instantaneous peak values ​​of turbulence intensity; and simplistic signal processing methods that fail to distinguish between wake turbulence and background turbulence, leading to turbulence intensity data containing numerous interference components and failing to accurately reflect the actual interference intensity of the ship wake.

[0085] Based on this, when obtaining the turbulence intensity of the ship's wake, three turbulence sensors are set on each side of the ship's navigation path. The sensors are installed at a height of 1 / 2 of the channel depth, and the sampling frequency of the sensors is set to 100Hz. Turbulence signals are continuously collected for 2 minutes as the ship passes by. The collected signals are subjected to Fourier transform to obtain the frequency spectrum. The signal energy value in the frequency range of 0.5-5Hz is extracted, and the ratio of this energy value to the background turbulence energy value before the ship passes is taken as the turbulence intensity of the ship's wake.

[0086] This scheme optimizes sensor placement and height to ensure the capture of typical characteristic signals of wake turbulence; employs a high sampling frequency of 100Hz to completely record instantaneous changes in turbulence intensity, avoiding the loss of crucial information; and introduces Fourier transform for frequency spectrum analysis to accurately extract characteristic frequency components of wake turbulence, effectively eliminating background turbulence interference and making turbulence intensity calculations more targeted and accurate. The standardized signal acquisition and processing workflow not only ensures data reliability and consistency but also provides high-quality parameters for wake influence correction in subsequent suspended sediment concentration calculations, upgrading the analysis of the impact of ship wakes on sediment suspension from qualitative description to quantitative calculation.

[0087] Traditional techniques for obtaining the cementation strength of surface sediments in riverbeds lack standardization and present the following technical problems: unclear sample collection depth, making it impossible to guarantee the collection of samples that reflect the characteristics of surface sediments; inconsistent sample preparation specifications, leading to a lack of comparability of test results from different laboratories; unreasonable shear test parameter settings, failing to consider the actual stress environment of the waterway, resulting in significant deviations between test results and actual cementation strength; and failure to control moisture content changes during the test, affecting the stability and reliability of the test results.

[0088] Based on this, when obtaining the cementation strength of surface sediments in the riverbed, sediment samples were collected from a depth of 0-20 cm in the surface layer of the riverbed. The samples were prepared into cylindrical specimens with a diameter of 5 cm and a height of 10 cm. A triaxial shear test was conducted on the specimens. During the test, the confining pressure was maintained at 100 kPa and the shear rate was 0.5 mm / min. The test was stopped when the shear displacement reached 15% of the specimen height. The maximum shear stress during the shear process was taken as the cementation strength of the surface sediments in the riverbed. At the same time, the water content of the specimens was monitored in real time during the test to ensure that the change in water content did not exceed 5%.

[0089] This scheme ensures that samples accurately reflect the sedimentary characteristics of the riverbed surface by specifying the sample collection depth; it improves the standardization and comparability of test results by standardizing sample specifications and test parameters; it sets reasonable confining pressure and shear rate to make the test conditions closer to the actual stress environment of the waterway, reducing test deviations; and it strictly controls changes in water content to ensure the stability of test results. The standardized test procedure not only provides technical support for the accurate acquisition of cementation strength but also makes the correction of cementation strength in subsequent sedimentation calculations more scientific, providing a unified data basis for comparative analysis of sediment deposition characteristics in different waterways.

[0090] Traditional techniques lack a dynamic correction mechanism for calculating the final sediment deposition volume, resulting in the following technical problems: relying solely on suspended sediment concentration without considering the impact of the cementation strength of surface sediments on sediment redeposition stability leads to significant deviations between predicted and actual deposition volumes in waterways where water content and organic matter content vary considerably; the time effect of organic matter decomposition is not incorporated, failing to reflect stability changes during long-term sedimentation; and the logical relationships between formula parameters are unclear, with the weights of each influencing factor not defined, hindering accurate quantitative analysis.

[0091] Based on this, the final amount of sediment deposition is calculated using the following formula:

[0092] ;

[0093] in, This represents the final amount of silt deposited. This represents the theoretical amount of sediment accumulation without cementing. This represents the actual concentration of suspended sediment. The concentration of suspended sediment when there is no ship interference; This is the concentration sensitivity coefficient; This is the bonding strength coefficient; The cementation strength of the surface sediments in the riverbed; The water content of the sediment; This represents the saturated water content of the sediment. The coefficient of organic matter decomposition; The rate of organic matter decomposition; The formula constructs a three-level correction logic for the effects of concentration, cementation strength regulation, and organic matter decomposition time. By using proportional and product terms to quantify the degree of influence of each factor, it achieves an organic linkage between suspended concentration, sediment physicochemical properties, and time factors.

[0094] As the actual suspended sediment concentration, it is a value that truly reflects the suspended sediment concentration in the waterway, obtained after considering various factors such as the influence of ship wakes, the difference between water flow velocity and the corrected critical starting velocity. In waterway management and maintenance, this parameter is of great significance for assessing the risk of sediment deposition and predicting changes in waterway depth.

[0095] This represents the suspended sediment concentration under conditions of no ship interference. It is calculated using a traditional sediment transport model based on local water flow, sediment characteristics, and riverbed topography, without considering the impact of ship traffic. This value can serve as a baseline reference for analyzing the additional impact of ship traffic on suspended sediment concentration.

[0096] The actual water flow velocity in the waterway is obtained through real-time monitoring using equipment such as current meters installed within the waterway. In practical applications, multiple current velocity monitoring points are set up at different locations and water depths along the waterway to obtain the distribution of water flow velocity across the entire waterway cross-section. The data from these monitoring points is transmitted in real-time to a data processing center via a data transmission system. After data fusion and analysis, accurate data on the actual water flow velocity in the waterway is obtained.

[0097] The critical starting velocity formula has been explained in detail above, and it is used here in conjunction with the actual water flow velocity in the channel. A comparison was made to calculate the effect of the difference in water flow velocity on the concentration of suspended sediment.

[0098] The velocity sensitivity coefficient was determined using a combination of statistical analysis and numerical simulation based on a large amount of experimental and actual monitoring data.

[0099] It reflects the sensitivity of suspended sediment concentration to differences in water flow velocity. This coefficient varies depending on different channel topography, sediment characteristics, and water flow conditions. For example, in narrow channels, changes in water flow velocity may have a more significant impact on suspended sediment concentration. The value will be relatively large; while in wide and calm waterways, The value is relatively small.

[0100] The wake influence coefficient, similar to the velocity sensitivity coefficient, is determined based on experimental and actual monitoring data and is used to quantify the impact of ship wakes on suspended sediment concentration. Ship wakes possess complex flow field structures and turbulent characteristics; the impact of wakes on sediment suspension varies depending on the type of ship, draft, and speed. Through monitoring and analysis of numerous different ship navigation scenarios, combined with hydrodynamic experiments, wake influence coefficients under different scenarios were determined. This ensures that the formula accurately reflects the effect of ship wake on suspended sediment concentration.

[0101] The intensity of ship wake turbulence is measured in real time by turbulence sensors installed on both sides of the waterway. High-precision, high-sensitivity turbulence sensors are selected to accurately capture turbulence signals in the ship wake. The sensor installation locations are carefully designed, typically in areas where the ship wake has a significant impact, and multiple sensors are placed at different heights and distances to obtain the spatial distribution of wake turbulence intensity.

[0102] The signals collected by the sensors are amplified, filtered, and then transmitted to the data acquisition system for analysis and calculation to obtain accurate data on the intensity of ship wake turbulence. The wake propagation distance is expressed in units of 1 / 2 oz. It is calculated by using the ship's position obtained through the ship positioning system and the position of the monitoring point.

[0103] In practice, the ship positioning system records the ship's navigation trajectory and position information in real time, while setting up multiple fixed monitoring points within the waterway and recording their coordinates. By calculating the distance between the ship's position and the monitoring point, the distance the wake travels to that monitoring point can be determined. As the ship sails, the wake gradually attenuates during propagation; therefore, the wake propagation distance is a crucial factor affecting the concentration of suspended sediment.

[0104] The wake attenuation coefficient is determined based on extensive experimental and observational data, considering the attenuation characteristics of wakes from different types of ships. It reflects the gradual weakening of the ship's wake intensity during propagation; different waterway conditions and ship parameters all affect the wake attenuation coefficient.

[0105] For example, in shallower waterways, the wake is more easily weakened by the riverbed. The value will be relatively large; while in deep and wide channels, the wake decays relatively slowly. The value is relatively small. The ship's draft, in units of Draft is an important parameter of a ship and is known during ship design and operation. A ship's draft affects the flow field structure and intensity of its wake, thus influencing its ability to suspend sediment. A greater draft can result in a stronger disturbance of sediment at the bottom by the ship's wake, therefore it is considered an important parameter in the formula. The ship speed influence coefficient, determined through experiments and data analysis, is used to quantify the impact of ship speed on suspended sediment concentration. Changes in ship speed alter characteristics such as wake velocity and turbulence intensity, thus affecting suspended sediment concentration differently. By monitoring and analyzing ship wake and suspended sediment concentration at different speeds, a quantitative relationship between ship speed and suspended sediment concentration was established, and the ship speed influence coefficient was determined. This is to ensure that the formula accurately reflects this effect. The ship's speed is obtained through its own speed measuring equipment. During navigation, the speed measuring equipment monitors the ship's speed in real time and transmits the data to the ship's control system and related monitoring platforms. This refers to the water flow velocity, which is different from the actual water flow velocity in the channel mentioned earlier. Correspondingly, it reflects the influence of water flow on ship wake and the movement of suspended sediment. The ratio of ship speed to water flow speed affects the propagation characteristics of ship wake in the water flow and its suspension effect on sediment, and is therefore considered as an important parameter combination in the formula.

[0106] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for predicting sediment deposition in waterways based on a hydrodynamic model, characterized in that, Includes the following steps: S1: The critical initiation velocity of sediments is corrected by the biomass, metabolic rate and biofilm thickness of the microbial community to obtain the corrected critical initiation velocity. S2: Based on the corrected critical starting velocity, combined with the turbulence intensity, propagation distance and draft of the ship wake, calculate the actual suspended sediment concentration in the channel; S3: Based on the suspended sediment concentration, combined with the cementation strength, water content and organic matter decomposition rate of the surface sediments of the riverbed, the amount of sediment deposition in the waterway is calculated.

2. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 1, characterized in that, The steps of S1 include: obtaining the critical initiation velocity of sediments without biological disturbance, and correcting the critical initiation velocity of sediments without biological disturbance by combining the biomass, metabolic rate, biofilm thickness, average spacing between sediment particles, organic matter content in sediments and total sediment concentration. The biomass of the microbial community was obtained by collecting sediment samples from different monitoring points at the bottom of the channel and then culturing and counting them in the laboratory. The metabolic rate was calculated by monitoring the oxygen consumption of sediment samples per unit time. Biofilm thickness was obtained by observing and measuring the surface of sediments using microscopic imaging techniques.

3. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 1, characterized in that, The steps of S2 include: obtaining the suspended sediment concentration and the actual water flow velocity in the channel when there is no ship interference; determining the velocity difference by combining the corrected critical starting velocity; and then correcting the basic value of suspended sediment concentration calculated from the velocity difference based on the turbulence intensity of the ship wake, the wake propagation distance, the ship draft, the ship speed, and the water flow velocity to obtain the actual suspended sediment concentration. The turbulence intensity of the ship's wake is obtained in real time by turbulence sensors installed on both sides of the waterway; the wake propagation distance is calculated by the ship's position obtained by the ship positioning system and the position of the monitoring point.

4. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 1, characterized in that, The steps in S3 include: obtaining the theoretical sedimentation amount without cementation, determining the concentration influence coefficient by combining the actual suspended sediment concentration with the suspended sediment concentration without ship interference, and then correcting the basic value of sedimentation amount calculated by the concentration influence coefficient based on the cementation strength, water content, saturated water content of sediment, organic matter decomposition rate and time of the riverbed surface sediments to obtain the final sedimentation amount. The cementation strength of the surface sediments in the riverbed was determined by indoor shear tests; Moisture content was obtained by measuring the moisture content of sediment samples using the drying method; The rate of organic matter decomposition was calculated by monitoring the change in organic matter content in sediment samples over time.

5. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 2, characterized in that, The corrected critical start-up velocity is calculated using the corrected critical start-up velocity calculation formula: ; in, The corrected critical start-up flow rate; The critical initiation velocity without biological disturbance; The coefficient representing the influence of biological disturbance; Microbial biomass; Microbial metabolic rate; The thickness of the biofilm; The average spacing between sediment particles; The organic matter influence coefficient; This refers to the organic matter content in the sediment; This represents the total concentration of sediments.

6. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 3, characterized in that, The actual suspended sediment concentration is calculated using the suspended sediment concentration formula: ； in, This represents the actual suspended sediment concentration. The concentration of suspended sediment when there is no ship interference; This refers to the actual water flow velocity in the waterway; The corrected critical start-up flow rate; The velocity sensitivity coefficient; The wake effect coefficient; The intensity of turbulence in the ship's wake; This refers to the wake propagation distance. This is the wake attenuation coefficient; The ship's draft; The coefficient representing the influence of ship speed; For ship speed; The velocity is the water flow velocity.

7. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 4, characterized in that, The final amount of siltation is calculated using the following formula: ； in, This represents the final amount of silt deposited. This represents the theoretical amount of sediment accumulation without cementing. This represents the actual suspended sediment concentration. The concentration of suspended sediment when there is no ship interference; This is the concentration sensitivity coefficient; This is the bonding strength coefficient; The cementation strength of the surface sediments in the riverbed; The water content of the sediment; This represents the saturated water content of the sediment. The coefficient of organic matter decomposition; The rate of organic matter decomposition; For time.

8. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 2, characterized in that, When obtaining the biomass of the microbial community, at least 5 different monitoring points were selected at the bottom of the channel. Three sediment samples were collected from each monitoring point. The collected samples were cultured and counted in the laboratory using the plate counting method. After removing outliers, the average value was taken as the microbial biomass of the monitoring point. The weighted average of the microbial biomass of all monitoring points was then taken as the biomass of the microbial community in the channel. The weights for calculating the weighted average are determined based on the channel width and water flow velocity at the location of each monitoring point. The larger the channel width and the slower the water flow velocity, the greater the weight of the monitoring point.

9. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 3, characterized in that, To obtain the turbulence intensity of the ship's wake, three turbulence sensors are installed on each side of the ship's path. The sensors are installed at a height of 1 / 2 of the channel depth, and the sampling frequency is set to 100Hz. Turbulence signals are continuously collected for 2 minutes as the ship passes by. The collected signals are subjected to Fourier transform to obtain the frequency spectrum. The signal energy value in the frequency range of 0.5-5Hz is extracted, and the ratio of this energy value to the background turbulence energy value before the ship passes is taken as the turbulence intensity of the ship's wake.

10. The method for predicting sediment deposition in waterways based on a hydrodynamic model according to claim 4, characterized in that, To obtain the cementation strength of surface sediments in the riverbed, sediment samples were collected from a depth of 0-20 cm in the surface layer. The samples were prepared into cylindrical specimens with a diameter of 5 cm and a height of 10 cm. A triaxial shear test was conducted on the specimens. During the test, the confining pressure was maintained at 100 kPa and the shear rate was 0.5 mm / min. The test was stopped when the shear displacement reached 15% of the specimen height. The maximum shear stress during the shear process was taken as the cementation strength of the surface sediments in the riverbed.

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