A mountain torrent beach sediment concentration monitoring method

Abstract

The application discloses a mountain torrent beach sediment concentration monitoring method, which comprises the following steps: filling water to an artificial water grass device arranged at the bottom of a riverbed of a control section of a torrent beach, obtaining multiple vertical jets sprayed from water outlet holes of the flexible water grass when the water grass stands up, forming an additional turbulent zone, determining an equivalent Manning roughness coefficient in the additional turbulent zone, adjusting the equivalent Manning roughness coefficient by adjusting the operation power of the artificial water grass device until the adjusted equivalent Manning roughness coefficient is greater than a basic Manning roughness coefficient, forming a state beneficial to uniform distribution of suspended solids, obtaining turbidity of multiple measuring points in the state, determining a turbidity variation coefficient of the section after water filling, and when the turbidity variation coefficient of the section after water filling decreases relative to an original section turbidity variation coefficient and decreases to a preset threshold range, determining that uniform distribution is formed, obtaining turbidity of at least one measuring point in the control section, and converting the turbidity of the measuring point into suspended sediment concentration. The method can improve the measurement accuracy of the sediment concentration.

Description

Technical Field

[0001] This invention relates to the field of river sediment monitoring technology, and more specifically to a method for monitoring sediment content in mountain rapids. Background Technology

[0002] Due to the topography and geomorphology, many rivers in mountainous areas of my country have small cross-sections in some sections, resulting in rapid flow and steep slopes. The distribution of water and sediment on the cross-section is extremely uneven. At the same time, due to the different particle sizes of suspended sediment, some large-particle suspended sediment will be deposited downwards, causing siltation of the riverbed and making it difficult for bottom-dwelling fish to migrate.

[0003] Currently, the monitoring of river sediment content by hydrological stations both domestically and internationally is based on field sampling and laboratory determination of suspended sediment. The conventional method used is to obtain sediment-containing water samples by setting up measuring lines and vertical lines at control sections, and then using point sampling, depth sampling, or width sampling. After indoor filtration, drying, and weighing, the suspended sediment content is calculated, and the sediment transport rate and sediment transport volume are estimated by combining flow data.

[0004] In recent years, foreign countries have widely adopted alternative monitoring technologies such as turbidity sensors and acoustic Doppler instruments to achieve continuous online estimation of sediment content based on the calibration of measured samples. However, the uneven distribution of water and sediment in mountain rapids is particularly prominent, resulting in large representative errors of turbidity sensors and acoustic Doppler instruments.

[0005] Domestically, manual standardized testing still dominates, while gradually moving towards automation and online monitoring. Due to the influence of factors such as the undulation of the main current, the undulation of the bed, the complex turbulent structure of the water flow, and the uneven distribution of local velocity in natural rapids, the suspended sediment concentration in the control section usually shows significant differences in the lateral and vertical directions, resulting in uneven turbidity distribution. Existing automated monitoring equipment is mostly designed for plain rivers or low-velocity river sections. Under the special hydraulic conditions of mountain rapids, the cross-section of the rapids is small, the flow velocity is high, and the slope is steep. The distribution of suspended sediment in the lateral and vertical directions is extremely uneven, and large-diameter suspended sediment is prone to sinking and accumulating, resulting in large measurement errors and failing to provide a suitable aquatic ecological environment for fish migration and plankton settlement. Summary of the Invention

[0006] To address the problems existing in the above-mentioned fields, this invention proposes a method for monitoring sediment content in mountain rapids. The method utilizes a multi-hole jet formed by an artificial aquatic plant device to uniformly distribute suspended sediment within the control section, thereby accurately measuring the sediment content of the river within the control section.

[0007] To address the aforementioned technical problems, this invention discloses a method for monitoring sediment content in mountain rapids, comprising the following steps: The turbidity of multiple measuring points along the water depth direction within the control section of the rapids is obtained, and the original turbidity variation coefficient is determined. By filling the artificial aquatic plant device installed at the bottom of the riverbed at the control section of the rapids with water, multiple vertical jets are ejected from the water outlet when the flexible aquatic plants stand upright, thereby forming an additional turbulence zone; wherein, the artificial aquatic plant device includes a pipe network laid at the bottom of the riverbed, and flexible aquatic plants connected to the pipe network, the flexible aquatic plants having a hollow inner cavity and a water outlet at the top. In the additional turbulent zone, the equivalent Manning roughness coefficient is determined based on the current relative submersion height and relative plant density of the flexible aquatic plants. The mechanical morphology of the flexible aquatic plants is changed by adjusting the operating power of the artificial aquatic plant device to adjust the equivalent Manning roughness coefficient until the adjusted equivalent Manning roughness coefficient is greater than the basic Manning roughness coefficient when the artificial aquatic plant device is not installed, thus forming a state conducive to the uniform distribution of suspended matter. Under conditions conducive to uniform distribution of suspended sediment, the turbidity at multiple measuring points within the control section is obtained to determine the coefficient of variation of turbidity at the section after the artificial aquatic plant device is filled with water. When the turbidity variation coefficient of the cross section after filling with water decreases relative to the original cross section turbidity variation coefficient, and decreases to within a preset threshold range, it is determined that the suspended sediment concentration forms a uniform distribution within the control cross section, and the turbidity of at least one measuring point within the control cross section is obtained. Based on the preset calibration relationship between water turbidity and suspended sediment content, the turbidity at this measuring point is converted into suspended sediment content.

[0008] Preferably, the current relative submersion height reached by the flexible aquatic plant is determined based on the ratio of the current average effective height reached by the flexible aquatic plant to the design water depth of the control section, specifically: In jet mode, the average effective height is the sum of the actual height reached by the flexible aquatic plant in the water flow and the vertical height of the jet ejected through the outlet hole; The actual height reached by the flexible aquatic plant in the water flow is determined based on the plant's uprightness, which is the ratio of the actual height reached by the flexible aquatic plant in the water flow to its average upright height in the air.

[0009] Preferably, the equivalent Manning roughness coefficient is obtained by substituting the plant species parameters of the flexible aquatic plants, the current relative submergence height of the flexible aquatic plants, and the relative density of the plants into the empirical formula for the equivalent Manning roughness coefficient of the submerged flexible aquatic plant channel.

[0010] Preferably, the step of obtaining the turbidity at multiple measuring points within the control section under conditions conducive to uniform distribution of suspended matter, and determining the coefficient of variation of turbidity at the section after the artificial aquatic plant device is filled with water, specifically includes: By setting up several vertical lines along the transverse direction on the control section, and setting multiple measuring points along each vertical line along the water depth direction, the turbidity of each measuring point is measured simultaneously after the artificial aquatic plant device is filled with water. Based on the turbidity at each measuring point after filling with water, determine the mean turbidity and standard deviation of the turbidity of the control section after filling with water; The ratio of the standard deviation of turbidity to the mean turbidity of the control section after water filling is used as the coefficient of variation of turbidity of the section after water filling of the artificial aquatic plant device.

[0011] Preferably, the additional turbulence zone satisfies the mixing time criterion; the mixing time criterion is that the lateral mixing time and the vertical mixing time within the control section are both less than the residence time of the water body through the artificial aquatic plant device in the effective mixing zone, and the effective mixing zone refers to the spatial range in which the vertical jet generated by the artificial aquatic plant device can significantly enhance the lateral and vertical turbulence diffusion.

[0012] Preferably, the preset threshold range includes the threshold requirement for the improvement rate of cross-sectional turbidity homogenization; The turbidity homogenization improvement rate of the cross section is determined based on the original cross section turbidity variation coefficient and the cross section turbidity variation coefficient after water filling; When the turbidity variation coefficient of the cross-section after water filling decreases to within the first preset threshold range, and the turbidity homogenization improvement rate of the cross-section reaches the second preset threshold, it is determined that the suspended solids concentration forms a uniform distribution within the control cross-section.

[0013] Preferably, the preset calibration relationship between water turbidity and suspended sediment content is a linear mapping relationship.

[0014] Preferably, the water source for filling the rapids is the natural water body of the river channel where the rapids are located.

[0015] Preferably, it also includes an artificial aquatic plant device for monitoring sediment content in mountain rapids, comprising: Pipeline network, laid at the bottom of the riverbed at the control section of the rapids; The biomimetic aquatic plant component is connected to the pipe network and has a hollow inner cavity with a water outlet at the top. A water inlet device, connected to the pipe network, is used to fill the pipe network and the hollow cavity of the biomimetic aquatic plant component with water; The pipeline network is laid in sections, and the sections are connected by fasteners. The pipeline network is connected to the biomimetic aquatic plant component by adapters.

[0016] Preferably, the flexible aquatic plant is made of flexible carbon fiber.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a method for monitoring sediment concentration in mountain rapids. It utilizes a jet stream formed by an artificial aquatic plant device to actively manage water flow, forcibly homogenizing the suspended sediment concentration across the entire cross-section. Once homogenization is determined, the turbidity at only one measuring point within the control section can accurately represent the average sediment concentration across the entire cross-section. This completely solves the industry pain point of data distortion and poor representativeness caused by uneven water and sediment distribution in rapids. The complex flow field changes after artificial aquatic plant jet intervention are transformed into a quantifiable equivalent Manning roughness coefficient, providing a macroscopic fluid dynamics quantitative indicator for the slowing and mixing effects in the additional turbulent zone. This not only confirms the effective formation of the additional turbulent zone but also guides the system to dynamically adjust the water-filling jet power according to the hydraulic conditions of different rapids, avoiding energy waste or insufficient mixing caused by blind jetting. The obtained cross-sectional turbidity variation coefficient provides an objective statistical measure reflecting the degree of data dispersion. By comparing the cross-sectional turbidity variation coefficients before and after water filling and setting a clear threshold range as the triggering condition for flow measurement, a rigorous mathematical standard is provided for determining the fuzzy physical phenomenon of whether suspended sediment is homogenized. This closed-loop feedback mechanism ensures that turbidity is collected only during the golden window period when water and sediment are truly and evenly mixed, eliminating misjudgments caused by the pulsation of rapids and greatly improving the stability and reliability of monitoring. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method for monitoring sediment content in mountain rapids proposed in this invention; Figure 2 This is a schematic diagram of the structure of the artificial aquatic plant device provided in an embodiment of the present invention; Figure 3 This is a multi-view structural diagram illustrating the connection between flexible aquatic plants and a pipe network, provided in an embodiment of the present invention. Detailed Implementation

[0019] The following will refer to the appendices in the embodiments of the present invention. Figures 1-3 The technical solutions in the embodiments of the present invention will be clearly and completely described. It should be understood that the terminology used in the present invention is only for describing particular implementation methods and is not intended to limit the present invention.

[0020] The present invention proposes a method for monitoring sediment content in mountain rapids, the design principle of which is as follows: Artificial aquatic plant devices are laid at the bottom of the riverbed at the control section of the rapids. By laying flexible aquatic plants with a certain submersion height and relative plant density at the bottom of the riverbed, and connecting the water pump and pipeline network to the hollow inner cavity of the flexible aquatic plants to jet, the uprightness of the flexible aquatic plants is controlled, the water flow velocity is slowed down, and the water flow is temporarily turbulent, so that the water and sediment can be temporarily and locally evenly distributed.

[0021] By using a hydraulic artificial aquatic plant device and a turbidity sensor, a multi-hole jet is formed by the hollow cavity of the flexible aquatic plant, which makes the suspended sediment in the control section evenly distributed. The turbidity sensor can easily and accurately measure the sediment content of the river in the control section.

[0022] A hydraulic artificial aquatic plant system slows down the flow at the bottom of the river, meeting the requirements for fish migration. By utilizing the attachment of flexible aquatic plants to microorganisms and plankton in the river, a small ecosystem is constructed, providing a suitable aquatic ecological environment for fish migration and plankton settlement.

[0023] The method proposed in this invention can not only homogenize suspended sediments of different particle sizes at different depths in a river cross section, but also separate the influence of riverbed sediment on river sediment content, making the determination of sediment content more accurate.

[0024] Example like Figure 1 As shown in the figure, an embodiment of the present invention discloses a method for monitoring the sediment content of rapids in mountainous areas, including the following steps: S1: Obtain the turbidity at multiple measuring points along the water depth direction within the control section of the rapids and determine the original section turbidity variation coefficient; S2: By filling the artificial aquatic plant device at the bottom of the riverbed at the control section of the rapids with water, multiple vertical jets are ejected from the outlet when the flexible aquatic plants stand upright, so as to form an additional turbulence zone. The artificial aquatic plant device includes a pipe network laid on the bottom of the riverbed and flexible aquatic plants connected to the pipe network. The flexible aquatic plants have a hollow inner cavity and a water outlet at the top. like Figure 2 As shown, the pipeline network (in) Figure 2 The corresponding section (corresponding to the plastic-steel composite bottom pipe) adopts a segmented splicing structure and is laid along the bottom of the riverbed (or the bottom of the water body). The pipe segments are connected end-to-end by fixing devices to form a pipe network extending along the direction of water flow. Above each pipe segment, flexible aquatic plants are vertically connected via adapters. Figure 2 The corresponding type is flexible carbon fiber aquatic plant. Flexible aquatic plants have a hollow inner cavity and a water outlet at the top (in... Figure 2 (The corresponding point is the dot or opening at the top of the aquatic plant). The outer ends of each pipe section are connected to the water pump via inlet pipes to receive external water.

[0025] like Figure 3The diagram shows a multi-view structural schematic of the connection between the flexible aquatic plant and the pipe network. The top left corner is the main view, the top right corner is the left view, the bottom left corner is the sectional view, and the bottom right corner is the top view. The main view shows the flexible aquatic plant connected to the pipe network via an adapter; the left view shows the flexible aquatic plant standing vertically above the pipe network; the sectional view shows the inner cavity of the pipe network connected to the hollow inner cavity of the flexible aquatic plant via an adapter, allowing water to be filled into the hollow inner cavity of the flexible aquatic plant; the top of the flexible aquatic plant has multiple water outlets, through which water is ejected after filling, forming a multi-jet stream. The top view shows that the multiple water outlets are evenly distributed circumferentially along the top of the flexible aquatic plant.

[0026] S3: In the additional turbulent zone, the equivalent Manning roughness coefficient is determined based on the current relative submersion height and relative plant density of the flexible aquatic plants. The mechanical morphology of the flexible aquatic plants is changed by adjusting the operating power of the artificial aquatic plant device to adjust the equivalent Manning roughness coefficient until the adjusted equivalent Manning roughness coefficient is greater than the basic Manning roughness coefficient when the artificial aquatic plant device is not installed, thus forming a state conducive to the uniform distribution of suspended matter. S4: Under conditions conducive to uniform distribution of suspended matter, obtain the turbidity at multiple measuring points within the control section and determine the coefficient of variation of turbidity at the section after the artificial aquatic plant device is filled with water. S5: When the turbidity variation coefficient of the cross section after filling with water decreases relative to the original cross section turbidity variation coefficient and decreases to within the preset threshold range, it is determined that the suspended solids concentration forms a uniform distribution within the control cross section, and the turbidity of at least one measuring point within the control cross section is obtained. S6: Based on the preset calibration relationship between water turbidity and suspended sediment content, convert the turbidity of this measuring point into suspended sediment content.

[0027] Specifically, in step S1, several vertical lines are laid out laterally along the control section, and multiple measuring points are set along each vertical line in the direction of water depth. The turbidity at each measuring point is monitored synchronously using sensors when no artificial aquatic plant devices are installed. Based on the turbidity at each measuring point, determine the mean turbidity and standard deviation of the turbidity at the control section when no artificial aquatic plant device is installed; The ratio of the standard deviation of turbidity to the mean turbidity of the control section without artificial aquatic plants is used as the turbidity variation coefficient of the control section without artificial aquatic plants, i.e., the original turbidity variation coefficient of the control section.

[0028] In this embodiment, the original cross-sectional turbidity variation coefficient at the bottom of the riverbed of the rapids beach control section and the cross-sectional turbidity variation coefficient after the artificial aquatic plant device is filled with water adopt the same measurement point layout. The difference is that it needs to be measured in advance before the artificial aquatic plant device is filled with water.

[0029] In step S2, the artificial aquatic plant device deployed at the bottom of the riverbed at the rapids control section in this embodiment consists of four components: a pipe network, adapters, fixers, and flexible aquatic plants. The pipe network, i.e., the rigid pipes at the bottom, is made of steel-plastic composite pipe, laid in sections to adapt to the riverbed topography, and the modules are fixed together by fixers. The bottom pipes are connected to the flexible aquatic plants via adapters. The flexible aquatic plants have a hollow inner cavity and a water outlet at the top. The flexible aquatic plants are made of flexible carbon fiber.

[0030] Water is pumped into the hollow interior of the flexible aquatic plants via a network of pipes to control their uprightness and increase the roughness of the riverbed. The water source is the natural water body of the river where the rapids are located.

[0031] When water is pumped into the artificial aquatic plant device, the flexible aquatic plants stand upright, increasing river resistance, slowing down the sediment in the riverbed, and balancing the concentration of suspended matter in the cross-section.

[0032] The water jets are generated through the outlet holes of the flexible aquatic plants, forming a multi-nozzle jet that further slows down the water flow above the plants. The navigation aid vessel's solar-powered batteries supply power to the water pumps. This embodiment utilizes a clean energy generation design, reducing energy consumption and achieving sustainable use.

[0033] The method proposed in this invention can intelligently control the water and sediment flow velocity at the cross-section of a rapid current, wherein: 1) When flow measurement is not required, the flow-slowing efficiency of the hydraulic artificial aquatic plant device only ensures the migratory ability of fish. By adjusting the operating power of the artificial aquatic plant device, the mechanical morphology of the flexible aquatic plants is changed to adjust the equivalent Manning roughness coefficient. That is, under the first operating power condition, the hydraulic artificial aquatic plant device is filled with water only, without jetting from the top, to keep the flexible aquatic plants upright. The porous structure of the flexible aquatic plants is conducive to providing a more suitable habitat for plankton and microorganisms, and can adsorb harmful substances that easily cause water pollution and eutrophication, providing a basic guarantee for improving the local ecology.

[0034] 2) When flow measurement is required, i.e., under the second operating power condition, water is pumped into the artificial aquatic plant device, and water jets are emitted from the outlet holes at the top of the flexible aquatic plants, temporarily and locally uniformly distributing the water and sediment. Turbidity sensors continuously record the turbidity at multiple measuring points, and the suspended sediment concentration is then calculated using the turbidity-sediment content calibration relationship. This process is particularly common in rivers where suspended sediment is dominant. The United States Geological Survey (USGS) explicitly uses turbidity as a commonly used proxy indicator for suspended sediment concentration. Since this step is only performed when flow measurement is required, it does not affect long-term flow velocity.

[0035] In step S3, the equivalent roughness coefficient is determined by designing experiment 1. The dual-power operating scheme is a multi-dimensional design to realize sediment concentration measurement, fish migration and small ecosystem construction.

[0036] In this embodiment, to demonstrate the effect of the artificial aquatic plant device under various hydraulic conditions, Experiment 1 is designed to provide a specific value for the equivalent roughness coefficient. Experiment 1 uses the equivalent roughness coefficient as the target object and controls the relative planting density of the plants. N The experiment was conducted to verify the actual improvement effect without changing the original parameters.

[0037] Existing technology uses fitting of flume test data points to determine a general basic Manning roughness coefficient empirical formula applicable to submerged flexible aquatic plant channels of different plant species i. ; in, For plant species i The uprightness, ( This refers to the height of the flexible aquatic plants after they have fallen over in the water flow. (meaning the average height of the object standing upright in the air) h To control the design water depth of the cross-section, The Manning roughness coefficient of the selected water tank test bench is given. , , This indicates that they are for different plant species. i The parameters related to growth status need to be determined through hydraulic experiments or field observations on specific aquatic plants. Among these, The value should be taken between 1.0 and 2.0. For plants with high flexibility, a value of 1.1 to 1.5 should be used, while for plants with high stiffness, a value of 1.5 to 2.0 can be used. For important projects, it is advisable to determine the value through hydraulic testing.

[0038] The equivalent Manning roughness coefficient affecting the aquatic plant channel can be obtained. The main parameters are: plant species i The current relative submersion height of the flexible aquatic plants and relative density of plants N The result is obtained by substituting the empirical formula for the general basic equivalent Manning roughness coefficient.

[0039] In this embodiment, the design water depths for three different control sections are given, respectively. h For each design water depth (30cm, 35cm, 40cm), three different flow rate data points were collected. Control velocities were then set for each design water depth. Q =0.04 0.07 0.10 A total of 9 sets of experimental results were obtained.

[0040] In this embodiment, the average upright height of artificial aquatic plants in the air is taken as... =10cm, taking the average effective height of flexible aquatic plants under the first operating power condition, i.e., the migratory condition. Equivalent to the height of flexible aquatic plants after they have collapsed in the water flow, the relative submersion height of the plants is... Under the second operating power condition, the vertical ejection height of the jet is The average effective height of the flexible aquatic plant at this operating power is the sum of the height of the flexible aquatic plant after it has collapsed in the water flow and the height of the jet ejected vertically through the outlet. The relative submersion height of the flexible aquatic plants corresponding to this operating power is: .

[0041] To optimize the experimental results, this embodiment uses a water level probe to measure the average effective height of flexible aquatic plants under different flow rates and velocities. , .

[0042] This innovative design is a hydraulic artificial aquatic plant, taking into account parameters related to plant species and growth status. i The coefficients are constant in both sets of tests with different operating power, and are derived from the data points under both sets of operating power based on the aforementioned equivalent Manning roughness coefficient. The calculation formulas were fitted to obtain the equivalent Manning roughness coefficient, which provides data support for the flow measurement effect of the artificial aquatic plant device deployed in this invention under different operating power.

[0043] Before obtaining the turbidity at multiple measuring points within the control section, the equivalent Manning roughness coefficient of the current state must be greater than the basic Manning roughness coefficient when no artificial aquatic plant device is installed, in order to confirm that the additional turbulent zone has formed an effective slow flow and mixing condition.

[0044] Turbidity of suspended matter was determined in Experiment 2. Due to the influence of factors such as the swing of the main current, the undulation of the bed, the complex turbulent structure of the water flow, and the uneven distribution of local velocity, the suspended sediment concentration in the control section usually varies significantly in both the lateral and vertical directions, resulting in uneven turbidity distribution.

[0045] ① Experimental Principle Turbidity and suspended solids concentration have a corresponding relationship. Under the conditions of relatively stable sediment gradation and water properties, it can be approximately considered that changes in turbidity can characterize changes in suspended solids concentration.

[0046] According to the HEC-RAS 2D Sediment Technical Reference Manual, the transport process of suspended matter in water flow follows the classical convection-diffusion law, and its governing equation is: ; In the formula, C This refers to the concentration of suspended solids. u , v , w These are the velocity components in the downstream, lateral, and vertical directions, respectively. These are the turbulent diffusion coefficients in the downstream, lateral, and vertical directions, respectively. For sediment settling speed; S This refers to the additional mixing effect generated by the artificial aquatic plant device.

[0047] This invention creates an additional turbulence zone by installing a hydraulic artificial aquatic plant device at the bottom of the control section and spraying water columns from bottom to top.

[0048] During its ascent, the jet entrains and disturbs the surrounding water, significantly enhancing the turbulent diffusion capacity in both the lateral and vertical directions within the cross-section. This increases the exchange rate of suspended matter within the cross-section, thereby reducing the turbidity gradient and gradually bringing the high-turbidity and low-turbidity zones closer together. The effect can be expressed as follows: ; That is, the concentration of suspended matter within the cross-section tends to be uniform. Due to turbidity T With suspended concentration C There is a linear or near-linear relationship: ; Therefore, when the concentration of suspended solids tends to be uniform, the turbidity of the cross section also tends to be uniform.

[0049] ② Theoretical Criteria To characterize the enhancing effect of the jet from the artificial aquatic plant device on the lateral and vertical mixing capabilities, this invention, after filling the artificial aquatic plant device with water, shows that the equivalent diffusion coefficients in the lateral and vertical directions within the cross-section increase as follows: ; ; In the formula, The initial velocity of the jet of water ejected from the outlet; The equivalent diameter of the outlet hole; , This is an empirical correction factor; These are the equivalent diffusion coefficients in the lateral and vertical directions after the artificial aquatic plant device is filled with water.

[0050] The suspended mass transport equation employs classical convection-diffusion theory, where the turbulent diffusion coefficients in the lateral and vertical directions are... All of these originate from the gradient diffusion closure of the turbulent flux term.

[0051] The vertical diffusion coefficient can be written based on Rouse theory. And combined with the distribution of eddy viscosity coefficient of open channel flow An estimation is performed; its depth-averaged form can be further approximated as: Frictional flow velocity can be calculate.

[0052] Lateral diffusion coefficient Usually according to Estimate the scale relationship and write it as follows: ,in, These are empirical coefficients. Based on the classical diffusion timescale. and the advection residence time scale The present invention further establishes a criterion for the homogenization of cross-sectional turbidity.

[0053] In this embodiment, in the additional turbulence zone, the mixing time criterion also needs to be met; the mixing time criterion is that the lateral mixing time and the vertical mixing time in the control section are both less than the residence time of the water body through the artificial aquatic plant device in the effective mixing zone. The effective mixing zone refers to the spatial range in which the vertical jet generated by the artificial aquatic plant device can significantly enhance the lateral and vertical turbulence diffusion.

[0054] The transverse mixing time and vertical mixing time within the control section can be expressed as follows: ; ; In the formula, B The effective water surface width of the cross section; H The average water depth of the cross section.

[0055] If the effective mixing zone length of the artificial aquatic plant device is If the average flow velocity across the cross section is U, then the residence time of the water in this mixing zone is: ; When satisfied This indicates that both lateral and vertical mixing can be basically completed before the water flows through the control section, demonstrating that the artificial aquatic plant device can achieve the homogenization requirement of suspended turbidity at the control section and form an additional turbulence zone.

[0056] ③ Test methods In step S4, the present invention controls the cross-section to be arranged with several vertical lines in a state conducive to uniform distribution of suspended sediment. Each vertical line is equipped with multiple measuring points along the water depth direction. The cross-sectional turbidity variation coefficient of the artificial aquatic plant device before and after filling with water is measured simultaneously. Specifically, this includes: The turbidity at each measuring point is recorded as follows: A total of There are 10 measurement points.

[0057] Determine the mean turbidity of the cross section for: ; Determine the standard deviation of cross-sectional turbidity for: ; Then determine the coefficient of variation of turbidity at the cross-section after filling with water. ,Right now for: ; in, Used to characterize the dispersion of turbidity distribution after water filling of the control section. The smaller the value, the more uniform the turbidity after the control section is filled with water.

[0058] Similarly, the above method was used to determine the coefficient of variation of turbidity at the original cross-section when filling the artificial aquatic plant installation device with water. .

[0059] In step S5, when the condition is met... and When the concentration drops to within a preset threshold range that characterizes the uniform distribution of suspended matter, it can be determined that the suspended matter concentration has formed a uniform distribution within the control section. The artificial aquatic plant device has a significant effect on the homogenization of suspended matter turbidity in the control section.

[0060] The preset threshold range includes the threshold requirement for the improvement rate of cross-sectional turbidity homogenization.

[0061] Based on the original cross-sectional turbidity variation coefficient and the cross-sectional turbidity variation coefficient after water filling, the cross-sectional turbidity homogenization improvement rate is defined. for: ; When the turbidity variation coefficient of the cross-section after water filling decreases to within the first preset threshold range, and the turbidity homogenization improvement rate of the cross-section reaches the second preset threshold, it is determined that the suspended solids concentration forms a uniform distribution within the control cross-section.

[0062] The preset threshold can be set according to the experimental accuracy requirements. In this embodiment, the preset threshold is set to 10% or 5%.

[0063] ④ Judgment Result If, after the artificial aquatic plant device is filled with water, the deviation between the turbidity at each measuring point in the control section and the average turbidity of the section is significantly reduced, and the standard deviation of the turbidity and the coefficient of variation of the turbidity of the section decrease significantly, it indicates that the device enhances the water-sediment mixing capacity in the rapid current section, weakens the lateral and vertical distribution differences of suspended turbidity, and transforms the turbidity of the control section from the original uneven distribution to a uniform distribution.

[0064] As the turbidity of the cross section tends to be uniform, the difference between the turbidity at local measuring points and the average turbidity of the cross section is significantly reduced. Therefore, the turbidity measurements at a single point or a few points can be used to represent the average suspended sediment concentration of the control section, thereby improving the representativeness, stability and efficiency of sediment content measurement in the rapidshoal section.

[0065] In step S6, based on the preset calibration relationship between water turbidity and suspended sediment concentration, the measurement point is converted into suspended sediment concentration, wherein the calibration relationship is a linear mapping relationship.

[0066] Under the condition of relatively stable sediment gradation and water properties, this embodiment uses turbidity as a proxy index of suspended sediment concentration. By obtaining the turbidity of at least one measuring point within the control section as the average turbidity of the control section, the average suspended sediment content of the control section can be calculated.

[0067] This invention also proposes an artificial aquatic plant device for monitoring sediment content in mountain rapids, comprising: Pipeline network, laid at the bottom of the riverbed at the control section of the rapids; The biomimetic aquatic plant component is connected to a pipe network and has a hollow inner cavity with a water outlet at the top. The water inlet device, connected to the pipe network, is used to fill the hollow cavity of the pipe network and the biomimetic aquatic plant components with water; The pipeline network is laid in sections, and the sections are connected by fasteners. The pipeline network is connected to the biomimetic aquatic plant components through adapters.

[0068] Specifically, in this embodiment, the biomimetic aquatic plant component is a flexible aquatic plant.

[0069] This invention, by deploying a hydraulic artificial aquatic plant device at the bottom of the control section of a rapid current, and combining water-filled erection with top jetting, can increase the roughness of the river channel, reduce local flow velocity, and enhance water-sediment mixing. This effectively improves the uneven distribution of water flow and suspended sediment in the cross-section of a rapid current river section in mountainous areas, and enhances the stability of water-sediment distribution at the control section.

[0070] The system employs an intermittent jetting mode for the artificial aquatic plant device, which can be activated on demand. When flow measurement is not required, the flexible aquatic plants can simply remain upright (balancing ecological considerations and basic slow flow). When flow measurement is needed, the jetting is activated instantly to homogenize the flow, avoiding long-term high-load operation of the equipment and significantly reducing energy consumption. At the same time, turbidity is used as a proxy indicator for suspended sediment concentration for calculation, eliminating the cumbersome process of traditional manual sampling, laboratory filtration and drying, and realizing long-term, continuous, and automated online estimation of sediment content under complex water conditions.

[0071] By utilizing the multi-nozzle jets and additional turbulence zones formed by artificial aquatic plants, the exchange and mixing capacity of suspended sediment within the control section is enhanced in both the lateral and vertical directions, thus making the turbidity distribution of the section more uniform. After the turbidity of the section is homogenized, the difference between the turbidity at local measuring points and the average turbidity of the section is significantly reduced. It is possible to use the turbidity measurements at a single point or a few points to represent the average suspended sediment concentration of the control section, and to calculate the sediment concentration by combining the calibration relationship between turbidity and sediment concentration, thereby improving the representativeness, stability, and efficiency of sediment concentration measurement in the rapid current section.

[0072] This invention employs a dual-power operation mode. When flow measurement is not required, the artificial aquatic plant device is simply filled with water to maintain its upright state. When flow measurement is needed, the artificial aquatic plant device is activated to achieve cross-sectional water and sediment homogenization through top jet. Thus, it takes into account multiple needs such as flow and sediment measurement, energy-saving operation, and ecological regulation. At the same time, the artificial aquatic plant device can also slow down the bottom flow velocity, improve fish migration conditions, and provide an environmental basis for microorganisms and plankton to attach and settle, which has good ecological benefits and sustainable application value.

[0073] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0074] Furthermore, unless otherwise stated, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All references to this specification are incorporated by way of citation to disclose and describe methods relating to those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

Claims

1. A mountain torrent bed sediment concentration monitoring method characterized by, Includes the following steps: The turbidity of multiple measuring points along the water depth direction within the control section of the rapids is obtained, and the original turbidity variation coefficient is determined. By filling the artificial aquatic plant device installed at the bottom of the riverbed at the control section of the rapids with water, multiple vertical jets are ejected from the water outlet when the flexible aquatic plants stand upright, thereby forming an additional turbulence zone; wherein, the artificial aquatic plant device includes a pipe network laid at the bottom of the riverbed, and flexible aquatic plants connected to the pipe network, the flexible aquatic plants having a hollow inner cavity and a water outlet at the top. In the additional turbulent zone, the equivalent Manning roughness coefficient is determined based on the current relative submersion height and relative plant density of the flexible aquatic plants. The mechanical morphology of the flexible aquatic plants is changed by adjusting the operating power of the artificial aquatic plant device to adjust the equivalent Manning roughness coefficient until the adjusted equivalent Manning roughness coefficient is greater than the basic Manning roughness coefficient when the artificial aquatic plant device is not installed, thus forming a state conducive to the uniform distribution of suspended matter. Under conditions conducive to uniform distribution of suspended sediment, the turbidity at multiple measuring points within the control section is obtained to determine the coefficient of variation of turbidity at the section after the artificial aquatic plant device is filled with water. When the turbidity variation coefficient of the cross section after filling with water decreases relative to the original cross section turbidity variation coefficient, and decreases to within a preset threshold range, it is determined that the suspended sediment concentration forms a uniform distribution within the control cross section, and the turbidity of at least one measuring point within the control cross section is obtained. Based on the preset calibration relationship between water turbidity and suspended sediment content, the turbidity at this measuring point is converted into suspended sediment content.

2. The mountain torrent rapids sediment concentration monitoring method according to claim 1, characterized by, The current relative submersion height of the flexible aquatic plant is determined based on the ratio of the current average effective height of the flexible aquatic plant to the design water depth of the control section, specifically: In jet mode, the average effective height is the sum of the actual height reached by the flexible aquatic plant in the water flow and the vertical height of the jet ejected through the outlet hole; The actual height reached by the flexible aquatic plant in the water flow is determined based on the plant's uprightness, which is the ratio of the actual height reached by the flexible aquatic plant in the water flow to its average upright height in the air.

3. The method for monitoring sediment content in mountain rapids according to claim 1, characterized in that, The equivalent Manning roughness coefficient is obtained by substituting the plant species parameters of the flexible aquatic plants, the current relative submergence height of the flexible aquatic plants, and the relative density of the plants into the empirical formula for the equivalent Manning roughness coefficient of the submerged flexible aquatic plant channel.

4. The method for monitoring sediment content in mountain rapids according to claim 1, characterized in that, Under conditions conducive to uniform distribution of suspended sediment, the turbidity at multiple measuring points within the control section is obtained, and the coefficient of variation of turbidity at the section after the artificial aquatic plant device is filled with water is determined. Specifically, this includes: By setting up several vertical lines along the transverse direction on the control section, and setting multiple measuring points along each vertical line along the water depth direction, the turbidity of each measuring point is measured simultaneously after the artificial aquatic plant device is filled with water. Based on the turbidity at each measuring point after filling with water, determine the mean turbidity and standard deviation of the turbidity of the control section after filling with water; The ratio of the standard deviation of turbidity to the mean turbidity of the control section after water filling is used as the coefficient of variation of turbidity of the section after water filling of the artificial aquatic plant device.

5. The method for monitoring sediment content in mountain rapids according to claim 1, characterized in that, The additional turbulence zone satisfies the mixing time criterion; the mixing time criterion is that the lateral mixing time and the vertical mixing time within the control section are both less than the residence time of the water body through the artificial aquatic plant device in the effective mixing zone, and the effective mixing zone refers to the spatial range in which the vertical jet generated by the artificial aquatic plant device can significantly enhance the lateral and vertical turbulence diffusion.

6. The method for monitoring sediment content in mountain rapids according to claim 1, characterized in that, The preset threshold range includes the threshold requirement for the improvement rate of cross-sectional turbidity homogenization. The turbidity homogenization improvement rate of the cross section is determined based on the original cross section turbidity variation coefficient and the cross section turbidity variation coefficient after water filling; When the turbidity variation coefficient of the cross-section after water filling decreases to within the first preset threshold range, and the turbidity homogenization improvement rate of the cross-section reaches the second preset threshold, it is determined that the suspended solids concentration forms a uniform distribution within the control cross-section.

7. The method for monitoring sediment content in mountain rapids according to claim 1, characterized in that, The preset calibration relationship between water turbidity and suspended sediment content is a linear mapping relationship.

8. The method for monitoring sediment content in mountain rapids according to claim 1, characterized in that, The water source for the filling is the natural water body of the river channel where the rapids are located.

9. An artificial aquatic plant device for monitoring sediment content in mountain rapids, applied to the method for monitoring sediment content in mountain rapids as described in any one of claims 1-8, characterized in that, include: Pipeline network, laid at the bottom of the riverbed at the control section of the rapids; The biomimetic aquatic plant component is connected to the pipe network and has a hollow inner cavity with a water outlet at the top. A water inlet device, connected to the pipe network, is used to fill the pipe network and the hollow cavity of the biomimetic aquatic plant component with water; The pipeline network is laid in sections, and the sections are connected by fasteners. The pipeline network is connected to the biomimetic aquatic plant component by adapters.

10. The artificial aquatic plant device according to claim 9, characterized in that, The flexible aquatic plant is made of flexible carbon fiber.

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