A method for observing small and medium scale tidal flat deposition rate

Abstract

The application discloses a kind of small and medium scale tidal flat deposition rate observation method, it is related to the technical field of automatic observation of tidal flat area silt deposition rate, comprising the following steps: step one, in tidal flat observation area, multiple tidal flat field automation measuring devices are arranged;Step two: the deposition rate is measured and calculated by tidal flat field automation measuring device;Step three, target component is used to provide image control point information for unmanned aerial vehicle aerial survey;Step four, unmanned aerial vehicle aerial survey data is collected and small and medium scale area deposition rate model is established;Unmanned aerial vehicle aerial survey photo is imported into three-dimensional modeling software, then the image control point information obtained in step three is used to carry out puncture, obtain the three-dimensional point cloud data of research area, and establish small and medium scale area deposition rate model;Step five, the deposition rate of the entire tidal flat observation area is obtained by using the tidal flat deposition rate calculated by tidal flat field automation measuring device to calibrate the small and medium scale area deposition rate model established.

Description

Technical Field

[0001] This invention relates to the field of automatic observation technology of sediment deposition rate in tidal flat areas, and more specifically to a method for observing sediment deposition rate in small and medium-scale tidal flats. Background Technology

[0002] Tidal flats, located at the confluence of land and sea, are broad, flat shallows formed under hydrodynamic conditions primarily driven by tidal currents and composed of fine-grained sediments. They are widely distributed across various environments, from sheltered bays and lagoons to fully exposed estuaries and deltas. Tidal flats are a valuable natural resource, providing numerous important ecosystem services, such as buffering sea-level rise, storm action, and coastal erosion; carbon sequestration; and providing natural habitats for a wide variety of rare and endangered flora and fauna. They can also be transformed into potential land resources through techniques such as reclamation.

[0003] Studying sediment deposition rates in tidal flat areas is crucial for understanding coastal protection capabilities, increasing potential land resources, and protecting biodiversity. For example, researching deposition rates in tidal flat areas and the dynamic evolution of tidal flat landforms under the combined influence of humans and nature can provide a basis for understanding the modern sedimentary processes in nearshore tidal flats of radiating sandbars, the appropriate utilization of tidal flat resources, and ecological environmental protection, thus possessing positive scientific significance and practical value.

[0004] In this invention, the large, medium, and small scales of tidal flat observations are mainly determined by the size of the observation area. Generally, large scale refers to tidal flat areas of hundreds or thousands of square kilometers observed through satellite remote sensing images; medium scale refers to high-resolution data of observation areas of tens of square kilometers obtained through low-altitude UAV remote sensing; and small scale refers to observations of tidal flat areas using manual beach running methods. Due to the limitations of manual beach running methods, the observation area is often concentrated at a few points or a few specific cross-sections.

[0005] Most existing studies rely on the analysis of field observation data. In terms of small-scale observation, long-term field tracking and measurement are not possible due to the muddy surface and difficult walking conditions of the tidal flats. Meanwhile, mesoscale UAV aerial surveys of tidal flats lack sufficient accuracy and effective data to calibrate the survey results. Therefore, how to provide a method for long-term continuous and accurate observation of sedimentation rates at small and medium scales is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] Purpose of the invention: To address the problems in the existing technology, a method for observing the deposition rate of small- to medium-scale tidal flats is provided.

[0007] Technical solution: A method for observing sedimentation rates in small- to medium-scale tidal flats, comprising the following steps:

[0008] Step 1: Deploy multiple automated on-site measurement devices in the tidal flat observation area; each automated on-site measurement device includes a measurement component, a target component, and a fixing component, which are fixed in the tidal flat observation area by the fixing component; the measurement component includes a pressure gauge and a laser rangefinder, which are connected as a whole by a data cable.

[0009] Step 2: Measure and calculate the sedimentation rate using an automated on-site measurement device for the tidal flat; record the flood pressure and time information of the observation area using a pressure gauge, and record the thickness information of the tidal flat sediments using a laser rangefinder; calculate the sedimentation rate measured by the automated on-site measurement device for the tidal flat based on the information recorded by the pressure gauge and the laser rangefinder.

[0010] Step 3: Use the target component to provide ground control point information for UAV aerial surveying;

[0011] Step 4: Collect UAV aerial survey data and establish a sedimentation rate model for small and medium-scale regions; import the UAV aerial survey photos into 3D modeling software, and then use the control point information obtained in Step 3 to perform point aggregator analysis to obtain 3D point cloud data of the study area and establish a sedimentation rate model for small and medium-scale regions.

[0012] Step 5: Use the tidal flat sedimentation rate calculated by the automated on-site measurement device to calibrate the established small-to-medium scale regional sedimentation rate model, and use the calibrated small-to-medium scale regional sedimentation rate model to obtain the sedimentation rate of the entire tidal flat observation area.

[0013] Furthermore, the pressure gauge is a self-recording pressure gauge, and the laser rangefinder is a self-recording laser rangefinder. Both the self-recording pressure gauge and the self-recording laser rangefinder are powered by a battery.

[0014] Furthermore, the target assembly includes a first target assembly and a second target assembly arranged in parallel; the first target assembly and the second target assembly have the same structure, each including two strip plates located in the same plane, the ends of the strip plates are fixedly connected in an L shape by mortise and tenon joints, and each of the upper and lower surfaces of the strip plates is provided with two pin-type cross joints.

[0015] The fixing assembly includes eight bidirectional support rods, both ends of which are cross-shaped female connectors that match the pin-type cross connectors. The first target assembly and the second target assembly are fixed by splicing four of the bidirectional support rods, and the remaining four bidirectional support rods are spliced ​​on the lower side of the first target assembly. The four bidirectional support rods on the lower side of the first target assembly are inserted into the tidal flat, and the first target assembly is in close contact with the tidal flat surface.

[0016] The pressure gauge is fixed on the upper surface of the first target assembly, and the sensing surface of the pressure gauge is placed parallel to the tidal flat surface; the laser rangefinder is installed on the bidirectional support rod between the first target assembly and the second target assembly, and the laser probe of the laser rangefinder is placed downward along the plumb line.

[0017] Furthermore, the fixing assembly also includes several unidirectional support rods; one end of each unidirectional support rod is a female cross-shaped connector, and the other end is a male cross-shaped connector; the male cross-shaped connectors are all matched with the female cross-shaped connectors; the unidirectional support rods are spliced ​​with the bidirectional support rods to increase the height of the bidirectional support rods.

[0018] Furthermore, the specific content of step two is as follows:

[0019] 1) Use a pressure gauge to record the flood pressure and time information of the observed area;

[0020] During high tide, when the water level rises and the pressure gauge and the first target component are submerged, the pressure gauge senses the water pressure and begins to automatically record the pressure value P and the corresponding time information; the formula for calculating the pressure value P is as follows:

[0021] p = ρgw

[0022] Where: p is the water pressure sensed by the pressure gauge; ρ is the density of seawater, generally between 1.02-1.07 g / cm3; g is the acceleration due to gravity; w is the water depth above the pressure sensor, that is, the distance from the water surface to the upper surface of the first target component;

[0023] 2) Use a laser rangefinder to record the thickness information of tidal flat sediments;

[0024] As the tide recedes, the pressure gauge senses the change in water pressure and transmits the signal to the laser rangefinder via a data cable. Upon receiving the signal, the laser rangefinder begins operation and records the deposition thickness d on the second target assembly after the tide recedes; the calculation formula is as follows:

[0025] d=hs

[0026]

[0027] Where: d is the thickness of the deposited layer on the first target assembly; h is the distance from the laser probe of the laser rangefinder to the upper surface of the first target assembly; s is the distance from the laser probe of the laser rangefinder to the top of the deposit; c is the speed of light; t is the time from when the laser probe emits the laser signal to when it receives the laser signal reflected from the top of the deposit.

[0028] 3) Calculate the sedimentation rate measured by the automated on-site measurement device of the tidal flat;

[0029] After one high and low tide, the time interval ΔT between two measurements of sediment thickness by a self-recording laser rangefinder is:

[0030] ΔT=T2-T1

[0031] T1 = T(p0)

[0032]

[0033] Where: ΔT is the time interval between two measurements of sediment thickness by the laser rangefinder; T2 is the time of the second measurement of sediment thickness by the laser rangefinder; T1 is the time of the first measurement of sediment thickness by the laser rangefinder; T(p0) is the time when the pressure p is recorded by the pressure gauge. The pressure p is recorded by the pressure gauge as ρ. s The time when g(dr); ρ s ρ is the density of the sediment; g is the gravitational acceleration; d is the deposition thickness on the first target assembly; r is the pressure gauge thickness;

[0034] The sedimentation rate δ measured by the automated on-site measurement device on the tidal flat is:

[0035]

[0036] Furthermore, the method for obtaining control point information in step three is as follows:

[0037] Using a handheld RTK, determine the RTK information (x, y, z) of the L-shaped outer corner point near the second target component; measure the vertical distance between the first and second target components and record it as D; then the control point information is (x, y, zD).

[0038] Furthermore, in step four, the method for taking aerial photos using a drone is as follows: a drone is used to conduct 5-camera oblique aerial photography within the tidal flat observation area, with the 5 cameras recording forward-looking, backward-looking, left-looking, right-looking, and downward-looking images respectively; the tilt angle of the side-view camera should be kept fixed during shooting, and the camera tilt angle should be set within the range of 40° to 50° for shooting.

[0039] Furthermore, in step five, the calibration method is as follows: statistical regression analysis is performed on the sediment rate information of the observation area recorded by multiple automated measurement devices in the tidal flat area and the three-dimensional point cloud data obtained in step four to construct a mesoscale sediment rate inversion model. The mesoscale sediment rate inversion model is then used to calibrate the UAV aerial survey data, thereby obtaining a more accurate tidal flat sediment rate after calibration.

[0040] Further, in step five, the specific calibration operations are as follows: Using multiple automated on-site measurement devices in the tidal flats, the average value and standard deviation of sediment rate data in the observation area are recorded to establish a log-normal distribution of 1000 sediment rate values. Using δ as the sediment rate parameter, a regression model relating δ to UAV aerial survey RTK elevation information is applied to each δ value in the random sediment rate distribution to obtain the matching distribution of the UAV aerial survey RTK elevation information. In these simulated UAV aerial survey RTK elevation information samples, a Gaussian random error equal to the residual standard error of the regression model is introduced to analyze the image and determine the required number of correction points, ultimately obtaining the sediment rate situation for the entire study area.

[0041] Furthermore, the target assembly and the fixing assembly are made of corrosion-resistant metal materials.

[0042] Beneficial effects: The method for observing sedimentation rates in small- and medium-scale tidal flats provided by this invention can continuously and accurately observe sedimentation rates over long periods. It is suitable for measuring sedimentation rates in small- and medium-scale tidal flats and solves the problem of small data volume obtained by manual beach running in general small-scale tidal flat areas. It also solves the problem of insufficient accuracy of sedimentation rates obtained by UAV aerial surveys in general medium-scale tidal flat areas. Attached Figure Description

[0043] Figure 1 This is a flowchart of a method for observing sedimentation rates in small- to medium-scale tidal flats according to the present invention;

[0044] Figure 2 This is a schematic diagram of the automated on-site measurement device for tidal flats of the present invention after it has been installed and fixed on the tidal flats;

[0045] Figure 3 This is a three-dimensional structural schematic diagram of the first target component in this invention;

[0046] Figure 4 This is a top view of the structure of the first target component in this invention;

[0047] Figure 5 This is a schematic diagram of the left-side structure of the first target component in this invention;

[0048] Figure 6 This is a schematic diagram of the pin-type cross joint in this invention;

[0049] Figure 7 This is a schematic diagram of the bidirectional support rod in the fixing component of the present invention;

[0050] Figure 8 This is a schematic diagram of the unidirectional support rod in the fixing component of the present invention;

[0051] Figure 9 This is a schematic diagram of the splicing process of a unidirectional support rod and a bidirectional support rod according to the present invention;

[0052] Figure 10 This is a schematic diagram of the splicing process of the three unidirectional support rods and the bidirectional support rods of the present invention;

[0053] Figure 11 This is a schematic diagram of the measurement component;

[0054] Figure 12 This is a cross-sectional view of the tidal flat deposition rate process recorded by an automated on-site measurement device.

[0055] Numbered in the diagram: Measurement component 1; Pressure gauge 101; Laser rangefinder 102; Data cable 103; Target component 2; First target component 201; Second target component 202; Strip plate 2021; Mortise and tenon joint 2023; Pin-type cross joint 2023; Fixing component 3; Two-way support rod 301; One-way support rod 302; Cross-shaped female connector 4; Cross-shaped male connector 5; Tidal flat surface 6. Detailed Implementation

[0056] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the embodiments.

[0057] This invention discloses a method for observing the deposition rate of small- to medium-scale tidal flats, the flowchart of which is shown below. Figure 1 As shown in the figure, this embodiment takes the Dongtai Tiaozi mudflat in Yancheng, Jiangsu Province as an example to describe the method for observing the sedimentation rate of small and medium-scale tidal flats.

[0058] Step 1: Deploy 9 automated on-site measurement devices in the tidal flat observation area;

[0059] like Figure 1 As shown, the automated on-site measurement device for tidal flats includes a measurement component 1, a target component 2, and a fixing component 3. The measurement component 1 and the target component 2 are fixed in the tidal flat observation area by the fixing component 3. The measurement component 1 includes a pressure gauge 101 and a laser rangefinder 102, which are connected as a whole by a data cable 103. The pressure gauge 101 is a self-recording pressure gauge, and the laser rangefinder 102 is a self-recording laser rangefinder.

[0060] The pressure gauge 101 is used to record the flooding time information of the observation area; the laser rangefinder 102 is used to record the tidal flat sediment thickness information of the observation area; the target component 2 provides image control point information for UAV aerial surveying;

[0061] The target component 2 includes a first target component 201 and a second target component 202 arranged in parallel; the first target component 201 and the second target component 202 have the same structure, such as... Figure 3-6As shown, each includes two strip plates 2021 located in the same plane. The ends of the strip plates 2021 are fixedly connected in an L-shape by mortise and tenon joints 2022. Each of the upper and lower surfaces of the strip plates 2021 is provided with two pin-type cross joints 2023.

[0062] The fixing component 3 includes eight bidirectional support rods 301, such as... Figure 7 As shown, both ends of the bidirectional support rod 301 are cross-shaped female connectors 4, and the pin-type cross connector 2023 matches the cross-shaped female connector 4; the first target assembly 201 and the second target assembly 202 are fixed by splicing four bidirectional support rods 301, and the remaining four bidirectional support rods 301 are spliced ​​on the lower side of the first target assembly 201. The four bidirectional support rods 301 on the lower side of the first target assembly 201 are inserted into the tidal flat, and the first target assembly 201 is in close contact with the tidal flat surface 6; the fixing component 3 also includes several unidirectional support rods 302; as Figure 8 As shown, one end of the unidirectional support rod 302 is a cross-shaped female connector 4, and the other end is a cross-shaped male connector 5; the cross-shaped male connector 5 is matched with the cross-shaped female connector 4.

[0063] like Figures 9-10 As shown, the unidirectional support rod 302 is spliced ​​with the bidirectional support rod 301 to increase the height of the bidirectional support rod 301.

[0064] In typical UAV aerial surveying operations, target components can be directly deployed on the ground for UAV photography. However, on tidal flats, due to the unique environmental characteristics, the surface experiences intermittent flooding, i.e., regular tidal rise and fall. This causes the target components to be periodically submerged, making them invisible to the UAV. Therefore, this invention incorporates a second target component 202 to prevent tidal fluctuations from affecting target clarity during UAV aerial surveying. The number of unidirectional support rods 302 can be increased or decreased based on actual conditions.

[0065] The pressure gauge 101 is fixed to the upper surface of the first target assembly 201, and the sensing surface of the pressure gauge 102 is placed parallel to the tidal flat surface. The laser rangefinder 102 is mounted on a bidirectional support rod 301 or a unidirectional support rod 302 between the first target assembly 201 and the second target assembly 202, and the laser probe of the laser rangefinder 103 is placed downwards along the plumb line. The pressure gauge 101 and the laser rangefinder 102 are powered by a battery.

[0066] The target assembly 2 and the fixing assembly 3 are made of corrosion-resistant metal materials. Coastal wetland silty tidal flats are highly corrosive due to frequent flooding. Corrosion-resistant metal materials can ensure the stability of the instrument during observation and facilitate recycling and reuse in the next field operation.

[0067] A total of nine automated on-site measurement devices were installed in this implementation, distributed throughout the tidal flat observation area. The required density of these devices in the study area depends on the topography, area, and accuracy requirements; a density of no less than 500 m² is recommended for coastal wetland tidal flat areas. 2 / each, and in areas with large terrain undulations and complex landforms, the number of on-site automated measurement devices for tidal flats can be increased by 20%.

[0068] Step 2: Measure and calculate the sedimentation rate using an automated on-site measurement device for the tidal flats;

[0069] A pressure gauge was used to record the flood pressure and time information of the observation area, and a laser rangefinder was used to record the thickness information of the tidal flat sediments. Based on the information recorded by the pressure gauge and the laser rangefinder, the sedimentation rate measured by the automated on-site measurement device of the tidal flat was calculated.

[0070] 1) Use a pressure gauge to record the flood pressure and time information of the observed area;

[0071] When the tide comes in during high tide and the pressure gauge 103 and the first target assembly 201 are submerged, the self-recording pressure gauge senses the water pressure on them and begins to automatically record the pressure value; throughout the process, waterproof protection must be ensured for the electrical components of the pressure gauge. When the self-recording pressure gauge and the first target assembly 201 are submerged, the water pressure value p sensed by the self-recording pressure gauge is:

[0072] p = ρgw

[0073] Where: p is the water pressure sensed by the pressure gauge; ρ is the density of seawater, typically between 1.02 and 1.07 g / cm³. 3 Between; g is the acceleration due to gravity; w is the water depth above the pressure sensor, that is, the distance from the water surface to the upper surface of the first target component 201.

[0074] 2) Use a laser rangefinder to record the thickness information of tidal flat sediments;

[0075] When the tide recedes, pressure gauge 101 senses the change in water pressure and transmits the signal to laser rangefinder 102 via data cable 103. Laser rangefinder 102 receives the signal, begins operation, and records the deposition thickness d on the first target assembly after the tide recedes. The calculation formula is as follows:

[0076] d=hs

[0077]

[0078] Where: d is the thickness of the deposited layer on the first target assembly; h is the distance from the laser probe of the laser rangefinder to the upper surface of the first target assembly; s is the distance from the laser probe of the laser rangefinder to the top of the deposit; c is the speed of light; t is the time from when the laser probe emits the laser signal to when it receives the laser signal reflected from the top of the deposit.

[0079] 3) Calculate the sedimentation rate measured by the automated on-site measurement device of the tidal flat;

[0080] After one high and low tide, the time interval ΔT between two measurements of sediment thickness by a self-recording laser rangefinder is:

[0081] ΔT=T2-T1

[0082] T1 = T(p0)

[0083]

[0084] Where: ΔT is the time interval between two measurements of sediment thickness by the laser rangefinder; T2 is the time of the second measurement of sediment thickness by the laser rangefinder; T1 is the time of the first measurement of sediment thickness by the laser rangefinder; T(p0) is the time when the pressure p is recorded by the pressure gauge. The pressure p is recorded by the pressure gauge as ρ. s The time when g(dr); ρ s ρ is the density of the sediment; g is the gravitational acceleration; d is the deposition thickness on the first target assembly; r is the pressure gauge thickness;

[0085] The sedimentation rate δ measured by the automated on-site measurement device on the tidal flat is:

[0086]

[0087] The specific letters represent the same meanings as above. Throughout the process, it is necessary to ensure the waterproof protection of the electrical components of the self-recording laser rangefinder.

[0088] Step 3: Use the target component to provide ground control point information for UAV aerial surveying.

[0089] The method for obtaining the image control point information is as follows: using a handheld RTK, determine the RTK information (x, y, z) at the outer corner of the L-shape near the second target component 202; measure the vertical distance between the first target component and the second target component and record it as D; then the image control point information is (x, y, zD).

[0090] Step 4: Collect UAV aerial survey data and establish a sedimentation rate model for small- to medium-scale regions;

[0091] Import the UAV aerial survey photos into the 3D modeling software, and then use the control point information obtained in step three to perform point pricking to obtain the 3D point cloud data of the study area and establish a small-to-medium scale regional sedimentation rate model.

[0092] The specific operation method is as follows: DJI Phantom 4 Pro drones are used to conduct 5-camera oblique aerial survey photography in the study area. The 5 cameras record front-view, rear-view, left-view, right-view and downward-view images respectively. The tilt angle of the side-view camera should be kept fixed during shooting. The camera tilt angle is set to 45° for shooting. The drone aerial survey photos are then imported into 3D modeling software. Then, the image control point information (x, y, zD) obtained by the target component in step 4 is used to prick points to obtain 3D point cloud data of the study area and establish a small-to-medium scale regional deposition rate model.

[0093] Step 5: Use the tidal flat sedimentation rate calculated by the automated on-site measurement device to calibrate the small-to-medium scale regional sedimentation rate model established in Step 4, and use the calibrated small-to-medium scale regional sedimentation rate model to obtain the sedimentation rate of the entire tidal flat observation area.

[0094] In this invention, the principle behind the calculation of sedimentary change rate using the small-to-medium scale regional sedimentary rate model established in step four is as follows: First, the elevation information of the entire tidal flat topography is obtained through UAV aerial surveying. Assuming the time for the two UAV flights is from t1 to t2, the change in tidal flat surface elevation *a* during the time from t1 to t2 can be calculated. Then, *a* / (t2-t1) is the sedimentary change rate. However, due to the limited accuracy of UAV aerial surveying, to determine whether the sedimentary rate calculated by the UAV is accurate, it is necessary to calibrate the entire model using the tidal flat sedimentary rate recorded by an automated on-site measurement device.

[0095] In this embodiment, the method for calibrating the sedimentation rate model in small and medium-scale regions is as follows: the sedimentation rate information of the observation area recorded by the nine automated on-site measurement devices of the tidal flats and the three-dimensional point cloud data obtained in step four are obtained and statistical regression analysis is performed to construct a mesoscale sedimentation rate inversion model. The constructed mesoscale sedimentation rate inversion model can be used to calibrate the UAV aerial survey data, thereby obtaining a more accurate tidal flat sedimentation rate after calibration.

[0096] The specific calibration procedure is as follows: The average and standard deviation of sediment rate data in the observation area were recorded using nine automated on-site tidal flat measurement devices to establish a log-normal distribution of 1000 sediment rate values. Using δ as the sediment rate parameter, a regression model relating δ to UAV aerial survey RTK elevation information was applied to each δ value in the random sediment rate distribution to obtain the matching distribution of the UAV aerial survey RTK elevation information. A Gaussian random error equal to the residual standard error of the regression model was introduced into these simulated UAV aerial survey RTK elevation information samples to analyze the images and determine the required number of correction points, ultimately obtaining the sediment rate situation for the entire study area.

[0097] This invention uses sedimentation rate data acquired by an automated on-site measurement device in tidal flats to calibrate a sedimentation rate model established for small- to medium-scale regions based on UAV aerial survey data. This allows for a more accurate overall sedimentation rate of the study area using the small- to medium-scale sedimentation rate model. This invention overcomes the problems of insufficient accuracy in sedimentation rates obtained from UAV aerial surveys in general medium-scale tidal flat areas and the limited amount of observational data obtained from manual beach surveys in general small-scale tidal flat areas.

[0098] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for observing sedimentation rates in small- to medium-scale tidal flats, characterized in that, Includes the following steps: Step 1: Deploy multiple automated on-site measurement devices for tidal flats in the tidal flat observation area; The automated on-site measurement device for tidal flats includes a measurement component (1), a target component (2), and a fixing component (3). The measurement component (1) and the target component (2) are fixed in the tidal flat observation area by the fixing component (3). The measurement component (1) includes a pressure gauge (101) and a laser rangefinder (102). The pressure gauge (101) and the laser rangefinder (102) are connected as a whole by a data cable (103). The target assembly (2) includes a first target assembly (201) and a second target assembly (202) arranged in parallel; the first target assembly is in close contact with the tidal flat surface, and the pressure gauge (101) is fixed on the upper surface of the first target assembly (201); the laser rangefinder (102) is installed on a bidirectional support rod (301) or a unidirectional support rod (302) between the first target assembly (201) and the second target assembly (202); the pressure gauge (101) is used to sense the arrival and receding of the tide, and the laser rangefinder (102) starts working after the tide recedes and records the deposition thickness deposited on the first target assembly after the tide recedes; Step 2: Measure and calculate the sedimentation rate using an automated on-site measurement device for the tidal flats; A pressure gauge was used to record the flood pressure and time information of the observation area, and a laser rangefinder was used to record the thickness information of the tidal flat sediments. Based on the information recorded by the pressure gauge and the laser rangefinder, the sedimentation rate measured by the automated on-site measurement device of the tidal flat was calculated. Step 3: Use the target component to provide ground control point information for UAV aerial surveying; Step 4: Collect UAV aerial survey data and establish a sedimentation rate model for small and medium-scale regions; Import the UAV aerial survey photos into the 3D modeling software, and then use the control point information obtained in step three to perform point pricking to obtain the 3D point cloud data of the study area and establish a small-to-medium scale regional sedimentation rate model. Step 5: Use the tidal flat sedimentation rate calculated by the automated on-site measurement device to calibrate the established small-to-medium scale regional sedimentation rate model, and use the calibrated small-to-medium scale regional sedimentation rate model to obtain the sedimentation rate of the entire tidal flat observation area.

2. The method for observing the sedimentation rate of small-to-medium scale tidal flats according to claim 1, characterized in that, The pressure gauge (101) is a self-recording pressure gauge, and the laser rangefinder (102) is a self-recording laser rangefinder. The self-recording pressure gauge and the self-recording laser rangefinder are powered by a battery.

3. The method for observing the sedimentation rate of small-to-medium scale tidal flats according to claim 1, characterized in that, The target assembly (2) includes a first target assembly (201) and a second target assembly (202) arranged in parallel; the first target assembly (201) and the second target assembly (202) have the same structure, each including two strip plates (2021) located in the same plane, the ends of the strip plates (2021) are fixedly connected into an L shape by mortise and tenon joints (2022), and the upper and lower surfaces of the strip plates (2021) are each provided with two pin-type cross joints (2023). The fixing component (3) includes eight bidirectional support rods (301), both ends of which are cross-shaped female connectors (4), which are matched with the pin-type cross connectors (2023); the first target component (201) and the second target component (202) are fixed by splicing four bidirectional support rods (301), and the remaining four bidirectional support rods (301) are spliced ​​on the lower side of the first target component (201); the four bidirectional support rods (301) on the lower side of the first target component (201) are inserted into the tidal flat, and the first target component (201) is in close contact with the tidal flat surface (6). The pressure gauge (101) is fixed on the upper surface of the first target assembly (201), and the sensing surface of the pressure gauge (101) is placed parallel to the tidal flat surface; the laser rangefinder (102) is installed on the bidirectional support rod (301) between the first target assembly (201) and the second target assembly (202), and the laser probe of the laser rangefinder (102) is placed downward along the plumb line.

4. The method for observing the sedimentation rate of small-to-medium scale tidal flats according to claim 3, characterized in that, The fixing component (3) also includes several unidirectional support rods (302); one end of the unidirectional support rod (302) is a cross-shaped female connector (4), and the other end is a cross-shaped male connector (5); the cross-shaped male connector (5) is matched with the cross-shaped female connector (4); the unidirectional support rod (302) is spliced ​​with the bidirectional support rod (301) to increase the height of the bidirectional support rod (301).

5. The method for observing the sedimentation rate of small-to-medium scale tidal flats according to claim 3, characterized in that, The specific content of step two is as follows: 1) Use a pressure gauge to record the flood pressure and time information of the observed area; During high tide, when the water level rises and the pressure gauge (101) and the first target assembly (201) are submerged, the pressure gauge senses the water pressure on them and begins to automatically record the pressure value P and the corresponding time information; the formula for calculating the pressure value P is as follows: in: The water pressure sensed by the pressure gauge; The density of seawater is generally between 1.02 and 1.07 g / cm³. 3 between; is the acceleration due to gravity; w is the water depth above the pressure sensor, i.e., the distance from the water surface to the upper surface of the first target component (201); 2) Use a laser rangefinder to record the thickness information of tidal flat sediments; When the tide recedes, the pressure gauge (101) senses the change in water pressure and transmits the signal to the laser rangefinder via the data line (103). The laser rangefinder (102) receives the signal, starts working, and records the deposition thickness d on the first target assembly after the tide recedes; the calculation formula is as follows: ， ； Where: d is the thickness of the deposited layer on the first target assembly; h is the distance from the laser probe of the laser rangefinder to the upper surface of the first target assembly; s is the distance from the laser probe of the laser rangefinder to the top of the deposit; c is the speed of light; t is the time from when the laser probe emits the laser signal to when it receives the laser signal reflected from the top of the deposit. 3) Calculate the sedimentation rate measured by the automated on-site measurement device of the tidal flat; The time interval between two measurements of sediment thickness using a self-recording laser rangefinder after one high and low tide. for: ， ， ； in: The time interval between two measurements of sediment thickness using a laser rangefinder; The time of the second measurement of sediment thickness by the laser rangefinder; The time when the laser rangefinder first measured the thickness of the sediment; Record the time when the pressure p is 0 using the pressure gauge; The pressure p is recorded by the pressure gauge. The time of the hour; The density of the sediment; d is the acceleration due to gravity; d is the deposition thickness on the first target component; r is the pressure gauge thickness; Sedimentation rate measured by automated on-site measurement device in tidal flats for: 。 6. The method for observing the sedimentation rate of small-to-medium scale tidal flats according to claim 5, characterized in that, The method for obtaining control point information in step three is as follows: Using a handheld RTK, determine the RTK information (x, y, z) of the L-shaped outer corner point near the second target component (202); measure the vertical distance between the first target component (201) and the second target component (202) and record it as D; then the control point information is (x, y, zD).

7. The method for observing the sedimentary rate of small-to-medium scale tidal flats according to claim 6, characterized in that, In step four, the method for taking aerial photos using a UAV is as follows: Use a drone to conduct 5-camera oblique aerial photography within the tidal flat observation area. The 5 cameras will record images from the front, back, left, right and down views respectively. The tilt angle of the side-view camera should be kept fixed during shooting, and the camera tilt angle should be set within the range of 40° to 50°.

8. The method for observing the sedimentation rate of small-to-medium scale tidal flats according to claim 7, characterized in that, In step five, the calibration method is as follows: statistical regression analysis is performed on the sediment rate information of the observation area recorded by multiple automated measurement devices in the tidal flats and the three-dimensional point cloud data obtained in step four to construct a mesoscale sediment rate inversion model. The mesoscale sediment rate inversion model is then used to calibrate the UAV aerial survey data to obtain a more accurate tidal flat sediment rate after calibration.

9. The method for observing the sedimentation rate of small-to-medium scale tidal flats according to claim 8, characterized in that, In step five, the specific calibration procedures are as follows: Log-normal distribution of 1000 sediment rate values ​​was established by recording the mean and standard deviation of sediment rate data in the observation area using multiple automated on-site tidal flat measurement devices. δ was used as the sediment rate parameter, and a regression model relating δ to UAV aerial survey RTK elevation information was applied to each δ value in the random sediment rate distribution to obtain the matching distribution of the UAV aerial survey RTK elevation information. Gaussian random errors equal to the residual standard error of the regression model were introduced into these simulated UAV aerial survey RTK elevation information samples to analyze the images and determine the required number of correction points, ultimately obtaining the sediment rate situation of the entire study area.

10. The method for observing the sedimentary rate of small-to-medium scale tidal flats according to claim 1, characterized in that, The target component (2) and the fixing component (3) are made of corrosion-resistant metal materials.

Images