Experimental device for simulating coastal aquifer pollutant migration and transformation under influence of sluice-controlled sea-entering river and experimental method thereof

Abstract

The invention discloses an experimental device for simulating coast aquifer pollutant migration and transformation under the influence of a gate-controlled sea-entering river and an experimental method thereof. Comprising a simulation water tank, a terrestrial surface-underground runoff simulation system, a pollutant simulation system and a simulation water gate system, wherein the simulation water tank is divided into a terrestrial surface-underground runoff generation area, a gate-controlled sea-entering river-coastal aquifer simulation area and a nonlinear tidal signal generation area from left to right; the simulation water gate system is located in the gate-controlled sea-entering river-coastal aquifer simulation area; the non-linear tide simulation system is connected with the non-linear tide signal generation area, and the tide-gate linkage system is used for associating a gate with tide; the pollutant monitoring system is used for carrying out in-situ monitoring on pollutants of a coast reservoir and an adjacent aquifer; and the camera shooting system is used for shooting a coast aquifer pollutant migration and transformation process under the influence of a gate-controlled sea-entering river in an experiment operation process. According to the invention, the pollutant migration and transformation process can be qualitatively and quantitatively simulated.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering technology, and in particular to an experimental apparatus and method for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice gate-controlled rivers flowing into the sea. Background Technology

[0002] Coastal areas, as the intersection of the terrestrial and marine hydrospheres, exhibit extremely complex water cycle processes. To meet the needs of flood control, drainage, freshwater storage, and tidal barrier, most river estuaries worldwide have tidal gates. The construction of these gates artificially alters the natural hydrodynamic conditions of rivers: when the gates are closed, the water level rises, creating a weak hydrodynamic environment; when they are opened, the water level drops sharply and the flow velocity increases dramatically. This drastic anthropogenic fluctuation not only alters the exchange relationship between surface water and groundwater but also, by controlling seawater upwelling, causes drastic spatial and temporal changes in salinity within the river channel, thus profoundly affecting the density current field and geochemical environment of coastal aquifers.

[0003] Unlike inland rivers, rivers flowing into the sea are constrained by both upstream runoff and downstream tides, resulting in a strong tidal correlation in sluice gate operation. In practical engineering, sluice gate opening and closing typically follow a phase coupling pattern: opening for flood discharge at low tide and closing for saltwater retention at high tide. This tidal-driven sluice gate control pulse mechanism causes dramatic and discontinuous step-like fluctuations in river levels, with the phase difference relative to tidal peaks and troughs varying depending on the estuary characteristics. This unique hydrodynamic process alters the hydraulic gradient of coastal aquifers, significantly driving the migration and transformation of pollutants within them.

[0004] Indoor experiments are an important means of reconstructing the migration and transformation of pollutants in coastal aquifers. However, most existing devices focus on seawater intrusion under simple sinusoidal tidal action (such as CN115266521B and CN113405830B), and the generation of tides requires the installation of a complex gantry system and damage to the laboratory ground (CN105241804A). They lack simulations of the opening and closing process of river gates flowing into the sea that are closely coupled with tidal phases, and cannot reproduce the dual effects of sudden changes in water level and salinity fluctuations caused by gate control, making it difficult to truly reflect their impact on the migration and transformation of pollutants in coastal aquifers. Summary of the Invention

[0005] Purpose of the invention: The first purpose of this invention is to provide an experimental device for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice gates controlling rivers flowing into the sea. This device is capable of qualitatively observing the tracer characteristics of the migration and mixing of fresh and saltwater interfaces in coastal groundwater under the influence of nonlinear tides, different gate opening and closing amplitudes, and gate response modes.

[0006] The second objective of this invention is to provide an experimental method for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice gates controlling rivers flowing into the sea. This method quantitatively measures the pore water pressure fluctuations and salinity spatiotemporal distribution at characteristic locations of the aquifer during the tidal-sluice gate linkage process, and establishes the response relationship between sluice gate control parameters (gear transmission ratio), groundwater recharge flux, and seawater intrusion distance under nonlinear tidal boundary conditions.

[0007] Technical Solution: To achieve the above objectives, the present invention provides an experimental device for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea. The device includes a simulated flume divided from left to right by a fully permeable partition into a land-based surface-ground runoff generation zone, a sluice-controlled river-coastal aquifer simulation zone, and a nonlinear tidal signal generation zone; a land-based surface-ground runoff simulation system connected to the land-based surface-ground runoff generation zone and used to simulate the lateral runoff replenishment process of groundwater; a pollutant simulation system for the fixed-point and quantitative input of pollutants into the aquifer and surface river channels; a simulated sluice gate system located within the sluice-controlled river-coastal aquifer simulation zone; a nonlinear tidal simulation system connected to the nonlinear tidal signal generation zone; a tidal-gate linkage system for linking the gate and the tide; a pollutant monitoring system for in-situ monitoring of pollutants in the coastal reservoir and adjacent aquifers; and a camera system for capturing the migration and transformation process of pollutants in the coastal aquifer under the influence of sluice-controlled rivers during the experimental operation.

[0008] Optionally, the land-based surface-to-ground runoff simulation system includes a surface water simulation system and a land-based groundwater recharge system. The surface water simulation system includes a platform, a surface water storage tank located on the platform and storing deionized water simulating surface water, a high-flow-rate variable frequency pump connected to the surface water storage tank via an inlet, and a water supply pipeline connecting the outlet of the high-flow-rate variable frequency pump to the surface water inlet of the land-based surface-to-ground runoff generation area. The land-based groundwater recharge system includes a groundwater storage tank storing deionized water simulating groundwater, a BW100 peristaltic pump whose inlet is connected to the groundwater storage tank via a transparent hose, and a transparent hose connecting the outlet of the BW100 peristaltic pump to the aquifer inlet of the land-based surface-to-ground runoff generation area.

[0009] Optionally, the pollutant simulation system includes a first standard solution tank storing a first colored pollutant solution for simulating the release of organic oil pollutants, a second standard solution tank storing a second colored pollutant for simulating the release of nutrient-rich domestic sewage or agricultural non-point source pollution, a third standard solution tank storing a third colored pollutant for simulating the release of high-salinity plumes of variable-density chemical pollutants, a first BW100 peristaltic pump with its inlet connected to the first standard solution tank, a second BW100 peristaltic pump with its inlet connected to the second standard solution tank, a third BW100 peristaltic pump with its inlet connected to the third standard solution tank, and a pollutant injection probe inserted into the sand layer inside the coastal aquifer of the simulated water tank.

[0010] Optionally, the simulated sluice gate system includes, from left to right, a gate channel device, a gate chamber assembly, and a porous energy dissipation apron plate. The gate channel device includes a channel body, permeable holes evenly distributed in the channel body, a stainless steel mesh on the inner wall of the channel body, a stainless steel slide rail at the bottom of the channel body, an impermeable adjusting slide plate connected to the stainless steel slide rail, and a flexible water-stop rubber sleeve at the end of the channel body and sealed to the gate chamber assembly. The gate chamber assembly includes a gate pier body with a flow passage in the middle, a gate guide groove embedded in the center of the inner side of the gate pier body, and a standard flange interface on the right side of the gate pier body. The porous energy dissipation apron plate is connected to the standard flange interface, and the surface of the porous energy dissipation apron plate is distributed with several staggered trapezoidal protrusions and energy dissipation holes.

[0011] Optionally, the nonlinear tidal simulation system includes a simulated seawater tank, a first pump connected to the outlet of the simulated seawater tank and acting as a constant-flow inlet pump connected to the inlet and outlet of a small-diameter simulated water tank to inject water into the simulated water tank at a constant flow rate, a second pump whose inlet is connected to the inlet and outlet of a large-diameter simulated water tank via a water supply pipe and whose outlet is connected to the simulated seawater tank via a water supply pipe for simulating low tide drainage, a flow regulating valve installed on the pipeline between the inlet and outlet of the large-diameter water tank and the second pump, a horizontal main gear disk horizontally installed at the top of the valve stem of the flow regulating valve, an input vertical gear meshing with the horizontal main gear disk, an input drive shaft coaxially arranged with the input vertical gear, a drive motor whose output shaft is connected to the input drive shaft, a water level sensor for detecting the water level, and a main controller for controlling the drive motor and having a built-in transformer signal generator. The main controller is based on the target tidal water level curve. The voltage signal controlling the drive motor is calculated and transmitted to the drive motor through a transformer signal generator.

[0012] Optionally, in the nonlinear tidal simulation system, the main controller is based on the target tidal level curve. To determine the voltage signal controlling the drive motor, the specific reverse solution is as follows: Within the nonlinear tidal signal generation region of the simulated water tank, the first water pump operates at a constant flow rate. Water is continuously injected into the body, and the second water pump discharges water at the required flow rate via a flow regulating valve. The water body is drained, and the simulated water tank is considered to have a cross-sectional area of A limited volume of water, for the target water level curve Perform time differentiation to calculate the required drainage flow rate at each moment. The calculation formula is: , Determine the required valve rotation angle: , , in The comprehensive flow characteristic function of the pump-valve system The inverse function of the pump-valve system's comprehensive flow characteristic function Established in advance through system calibration experiments; For the obtained By performing the time derivative, the required valve rotation angular velocity is obtained: , Considering gear ratio , To input the pitch circle radius of the vertical gear, Given the pitch circle radius of the horizontal main gear, the required angular velocity of the motor is: , According to the electromechanical characteristic equation of a DC motor, the relationship between the motor angular velocity and the terminal voltage is as follows: , in The motor speed constant is For armature resistance, This is the load current; The drive motor is based on the voltage signal The polarity controls the direction of rotation, and the rotation speed is controlled according to the voltage amplitude; The water level sensor collects the actual water level in real time. The data is then transmitted to the main controller, which compares the actual water level with the target water level and calculates the water level deviation. , The pre-calculated voltage signal is corrected in real time based on a PID feedback control algorithm. , in , , These are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

[0013] Optionally, the tidal gate linkage system includes a vertical drive shaft coaxially arranged at the bottom with the horizontal main gear disk, a horizontal driven gear turntable located at the top of the vertical drive shaft, a variable speed vertical gear set in which any gear meshes perpendicularly with the horizontal driven gear turntable, a top transverse drive shaft for passing through the variable speed vertical gear set, a stainless steel frame for supporting the top transverse drive shaft, a hub passing through the top transverse drive shaft via a tightening sleeve, a steel strand wound on the hub, and a water-blocking baffle located at the end of the steel strand and capable of opening and closing vertically to simulate the gate of a sluice gate system.

[0014] Optionally, the pollutant monitoring system includes a sampling port located on the back of the simulated water tank, a sensor deployment port located on the back of the simulated water tank, a pollutant sensor located in the sensor deployment port, a pollutant data processor connected to the pollutant sensor, and a display connected to the pollutant data processor.

[0015] Optionally, the camera system includes a high-definition camera located in front of the simulated water tank, a computer connected to the high-definition camera, a light-blocking curtain surrounding the camera and the simulated water tank, and lighting fixtures located directly above the simulated water tank.

[0016] The experimental method of the experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in this invention, includes the following steps: S1. Sieve white quartz sand according to experimental requirements. The simulated seawater in the simulated seawater tank is prepared by mixing deionized water and industrial salt in a mass ratio and stirring thoroughly until completely dissolved before use. S2. White quartz sand is filled into the simulated area of ​​the sluice-controlled river-coastal aquifer using a saturated method, ensuring that the water level remains above the sand surface throughout the filling process. Sand is filled in layers while water is being injected. According to the experimental design, a sluice-controlled river channel device is installed inside the simulated area of ​​the sluice-controlled river-coastal aquifer. The channel body is fixed above the simulated water tank using an angle adjustment bracket, with the permeable holes at the bottom of the channel body facing downwards and in contact with the aquifer. The position of the impermeable adjustment slide is adjusted, and the length of the permeable area is controlled within the range of 40cm to 100cm according to experimental requirements. The inclination angle of the channel body is adjusted, and the gate chamber assembly is installed at the downstream end of the channel body. The gate pier body is sealed to the end of the channel body using a flexible water-stop rubber sleeve. The porous energy dissipation abutment plate is fixed to the flange interface on the downstream side of the gate pier body. S3. Inject deionized water into the surface water storage tank and the groundwater storage tank respectively; prepare standard pollutant solutions into the first standard solution tank, the second standard solution tank and the third standard solution tank respectively; insert the pollutant injection probe into the simulated water tank, and adjust the position of the probe tip to near the upstream, midstream or downstream interface of the aquifer according to the experimental design. S4. Pour the prepared simulated seawater into the simulated seawater tank, start the first water pump, and adjust its flow rate to a constant value. The second water pump is started, and the main controller operates according to the target tidal water level curve. The voltage signal controlling the drive motor is obtained and transmitted to the drive motor through a transformer signal generator. The drive motor rotates forward and backward according to the voltage signal, driving the input vertical gear to rotate, which in turn causes the horizontal main gear to rotate. Through gear meshing, the opening of the flow regulating valve changes, thus changing the actual drainage flow of the second water pump 502. Observe whether the water level in the nonlinear tidal signal generation area exhibits periodic rises and falls, ensuring that the water level change amplitude meets the design requirements. According to the experimental requirements, select a suitable gear in the variable speed vertical gear set to mesh with the horizontal driven gear turntable, and set different mechanical transmission ratios. Fix one end of the steel strand in the spiral groove of the hub, and connect the other end to the top of the water-blocking baffle. Adjust the length of the steel strand so that the lower edge of the water-blocking baffle is a certain distance from the bottom of the river channel. Start the transformer signal generator, set the tidal waveform parameters, and ensure that the tidal water level change and the gate lifting and lowering action can be synchronized. Verify that during low tide, the flow regulating valve opens, the water-blocking baffle rises, and the gate opens; during high tide, the flow regulating valve closes, the water-blocking baffle falls, and the gate closes. S5. According to the experimental design, install pollutant sensors in the sensor mounting holes on the back of the simulated water tank; lead the cables of the pollutant sensors out through the wiring holes on the back of the simulated water tank and connect them to the pollutant data processor; connect the pollutant data processor to the monitor, set the data acquisition frequency, and display the pollutant concentration change curves at each monitoring point in real time; set up a high-definition camera on the front of the simulated water tank, and adjust the focus to ensure that the entire simulated area of ​​the sluice-controlled river-coastal aquifer is within the field of view; evenly arrange lighting panels directly above the simulated water tank; connect the high-definition camera to the computer via a data cable; build a light-blocking curtain around the simulated water tank to surround the high-definition camera, lighting fixtures, and the simulated water tank, creating a darkroom environment; S6. Activate the terrestrial surface-subsurface runoff simulation system. Inject the designed flow rate of surface runoff into the river channel using a high-flow-rate variable frequency pump, and inject the designed flow rate of subsurface runoff into the aquifer inlet using a BW100 peristaltic pump to simulate terrestrial hydrological processes. Activate the nonlinear tidal simulation system. Start the first and second pumps, and control the drive motors using a transformer signal generator to generate the designed nonlinear tidal waveform. The inlet and outlet of the small-diameter and large-diameter flumes operate simultaneously, creating periodic water level fluctuations within the nonlinear tidal signal generation zone. After the river flow, groundwater runoff, and tidal waveforms have stabilized for a period of time, the pollutant simulation system is activated. Based on the experimental design, one, two, or three BW100 peristaltic pumps are selected. Different colored pollutant solutions are injected into the aquifer or designed location in the river channel via the pollutant injection probe. During the experiment, water samples are periodically collected from different depths and locations of the aquifer using a syringe through the sampling port on the back of the simulated flume. The complete pollutant injection-migration-dilution-transformation process is recorded. The specific steps are as follows: S6.1. Without activating the nonlinear tidal simulation system and the tidal-gate linkage system, record the initial reference water level after the water level in the simulation tank stabilizes. and background concentration at each monitoring point ,in The spatial coordinates of the pollutant sensor in the simulated zone of the sluice-controlled river flowing into the sea and the coastal aquifer. The horizontal distance from the landside boundary. , The vertical height from the bottom of the tank. ; S6.2. Start the terrestrial surface-subsurface runoff simulation system and record the input flux; inject the designed flow rate of surface runoff into the river channel using a high-flow-rate variable frequency pump and record the surface runoff input flow rate. Groundwater recharge flow rate was injected into the aquifer inlet using a BW100 peristaltic pump at the designed flow rate, and the flow rate was recorded. After the river flow, groundwater runoff, and aquifer water level have stabilized, proceed to the next step. S6.3. Start the nonlinear tidal simulation system, record the tidal water level time series, start the first and second water pumps, and control the drive motor through the transformer signal generator to generate a nonlinear tidal waveform; deploy water level sensors in the nonlinear tidal signal generation area to record the real-time tidal water level time series. ; S6.4. Start the tidal gate linkage system, record the gate status parameters, and record the gear transmission ratio set in the current experiment. Measure the displacement of the water-blocking baffle and record the time series of the gate opening in real time. And calculate the gate state function accordingly. : , Simultaneously record the moment when the gate switches from closed to open during each tidal cycle. and the moment of switching from on to off Calculate the gate opening duration in a single cycle. ; S6.5. Start the pollutant simulation system, record the injection parameters, and select to start the first BW100 peristaltic pump (or the second or third BW100 peristaltic pump) according to the experimental design. Insert the pollutant probe into the simulated water tank at the designed position and record the pollutant injection flow rate. and injection concentration The injection location coordinates are ; S6.6. Run the experiment continuously for a period of time, and collect the following parameter data synchronously: River water level: Recording the time series of river water levels in variable permeability channels. ; Pollutant concentration field: Pollutant sensors collect pollutant concentrations at each monitoring point. The pollutant data processor and display show the concentration-time curve in real time; the spatial average concentration of the pollutants from the sensors within the river channel is calculated respectively. Spatial average concentration of sensors within the aquifer ; Salinity distribution: Conductivity at each monitoring point is collected synchronously using pollutant sensors and converted into salinity. Used to identify the location of the brackish water interface; Pollutant plume optical images: High-resolution cameras periodically capture frontal images of the simulated aquifer area at time intervals to obtain the spatial distribution grayscale field of the stained pollutants. Convert grayscale values ​​into a two-dimensional concentration field Pollutant concentration based on pollutant sensor (702) Concentration field obtained by correcting optical images ; During the experimental operation, the following key exchange fluxes were estimated online based on the collected water level data: River-aquifer infiltration exchange flow: Because the river water level is always higher than the aquifer groundwater level, river water continuously replenishes the aquifer through unidirectional downward infiltration of the riverbed medium. River-aquifer infiltration exchange flow... The value is always positive; according to Darcy's law, the vertical infiltration exchange flow from the river channel to the aquifer is: , in, The riverbed permeability coefficient, The effective infiltration area between the riverbed and the aquifer. The thickness of the permeable layer in the riverbed. This refers to the elevation of the riverbed. The water level in the permeable channel becomes the river level. Gate discharge flow rate: calculated according to the gate hydraulic formula: , in, For the clear width of the gate, The real-time tidal water level downstream of the sluice gate. It is the acceleration due to gravity; S7. After the experiment, all collected data were processed, and a quantitative analysis of the migration and transformation of pollutants in the coastal aquifer under the influence of the sluice gate-controlled river flowing into the sea was conducted. All pollutant sensor data were then standardized to the same time reference. For concentration time series Perform median filtering for noise reduction; A set of mass conservation equations for a coupled two-region system of sluice-controlled river channels and coastal aquifers was established. The sluice-controlled river-coastal aquifer system was divided into two coupled subsystems: the river channel region and the coastal aquifer region. Pollutant mass conservation equations were established for each subsystem. River channel mass conservation equation: , Mass conservation equation for coastal aquifer regions: , in The volume of water in the river channel; The volume of the aquifer; The average pollutant concentration in the river channel. The average pollutant concentration in the aquifer. For surface input flow, Inputting pollutant concentrations to the surface; For groundwater recharge flow, The concentration of pollutants in groundwater. This refers to the infiltration exchange flow between the river channel and the aquifer. The discharge flow rate of the gate; This is the gate state function. This refers to the discharge flow from the aquifer to the sea. This refers to the seawater intrusion flow into the aquifer. The concentration of pollutants in seawater, Porosity To inject pollutants into the river flow, Injecting aquifer flow to pollutants, To determine the concentration of injected pollutants; The rate of change of pollutant mass in the river over time; The pollutant flux carried in by surface runoff, The flux of pollutants carried away by the aquifer is replenished by the infiltration of river water. The amount of pollutants discharged when the gate is opened. The flux of tracer pollutants injected into the river during the experiment; The rate of change of the mass of pollutants in the pore water of the aquifer over time. Porosity; The flux of pollutants carried by terrestrial groundwater replenishment. This refers to the flux of pollutants carried by river water as it infiltrates into the aquifer. This refers to the pollutant flux carried away by the aquifer as it discharges towards the sea. This refers to the flux of pollutants brought in by seawater intrusion into the aquifer. The flux of tracer pollutants injected into the aquifer during the experiment; pass The project achieves coupling between two subsystems: the river channel and the aquifer. The river channel is the source of pollutants, and the aquifer is the sink. The gate state function... The total amount of pollutants entering the aquifer is indirectly regulated by controlling the discharge flow rate.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) This invention can intuitively simulate and characterize the synergistic effect of tidal dynamics and sluice gate regulation on the salinity transport of coastal aquifers through a mechanical linkage mechanism; (2) This invention realizes the physical simulation of different sluice gate control strategies through an adjustable variable speed gear transmission system, providing a flexible experimental platform for studying the groundwater dynamics process under the influence of sluice gate control. (3) The multi-physics field monitoring system and high-resolution camera system integrated in this invention realize comprehensive in-situ monitoring of groundwater dynamic field and chemical field, and can simultaneously acquire the spatiotemporal distribution of pollutant concentration and hydrodynamic parameters; (4) By precisely controlling the pollutant injection flow rate, this invention can simulate the emission rate of pollution sources of different intensities; by selectively turning on or off specific peristaltic pumps, it can achieve flexible switching between single pollutant or mixed pollutant emissions; by adjusting the position of the probe, it can simulate the migration and diffusion patterns of point source pollution at different locations. (5) This invention can generate nonlinear tidal waves with asymmetry, uneven high and low tides and non-stationary characteristics, and truly reproduce the tidal wave characteristics of complex estuaries. Under conditions that are closer to the real hydrodynamic environment of estuaries, it can conduct in-depth research on the hysteresis effect of groundwater level, tidal filtration effect and nonlinear law of salt transport under the combined action of nonlinear tides and sluice gates, and provide a scientific basis for the protection of coastal water resources and engineering scheduling under complex sea conditions. Attached Figure Description

[0018] Figure 1 This is a schematic front view of the device of the present invention; Figure 2 This is a schematic diagram simulating a sluice gate and energy dissipation plate; Figure 3 This is a schematic diagram of the sluice gate river channel device of the present invention; Figure 4 This is a schematic diagram of the nonlinear tidal simulation system of the present invention; Figure 5 This is a schematic diagram of the tidal gate linkage system of the present invention; Figure 6 This is a schematic diagram of the gate of the present invention; Figure 7 This is a schematic diagram of the pollutant monitoring system and high-resolution camera device of the present invention; Figure 8 This is a flowchart of the reverse control of the nonlinear tidal simulation system in this invention; Figure 9 This is the complete process of the five-stage reverse chain of shallow water deformation tides in this invention; The attached diagrams are labeled as follows: 1. Simulated water tank; 101. Transparent tempered glass plate; 102. Metal plate; 103. Fully permeable partition plate; 104. Acrylic plate; 105. Mesh; 106. Surface water inlet; 107. Underground water inlet; 108. Small-diameter water tank inlet and outlet; 109. Large-diameter water tank inlet and outlet; 110. Terrestrial surface-underground runoff generation zone; 111. Sluice-controlled river-coastal aquifer simulation zone; 112. Nonlinear tidal signal generation zone. 2. Terrestrial Surface-Subsurface Runoff Simulation System, 201. Surface Water Simulation System, 202. Terrestrial Subsurface Recharge System, 203. Surface Water Storage Tank, 204. High-Flow Variable Frequency Pump, 205. Water Transmission Pipeline, 206. Storage Platform, 207. Subsurface Water Storage Tank, 208. BW100 Peristaltic Pump, 209. Silicone Transparent Flexible Hoses. 3. Pollutant simulation system; 301. First standard solution tank; 302. Second standard solution tank; 303. Third standard solution tank; 304. First BW100 peristaltic pump; 305. Second BW100 peristaltic pump; 306. Third BW100 peristaltic pump; 307. Pollutant injection probe. Simulated sluice gate system 4, sluice gate channel device 401, sluice chamber assembly 402, porous energy dissipation guard plate 403, channel body 4011, permeable hole 4012, stainless steel mesh 4013, impermeable adjusting slide plate 4014, stainless steel slide rail 4015, flexible water-stop rubber sleeve 4016, sluice gate pier body 4021, gate guide groove 4022, flange interface 4023, rubber sealing strip 4024, trapezoidal protrusion 4031, energy dissipation hole 4032, bolt 4033; Nonlinear tidal simulation system 5, first water pump 501, second water pump 502, flow regulating valve 503, horizontal main gear disk 504, input vertical gear 505, input transmission shaft 506, drive motor 507, transformer signal generator 508, simulated seawater tank 509, water level sensor 510, main controller 511; Tidal gate linkage system 6, vertical drive shaft 601, horizontal driven gear turntable 602, variable speed vertical gear set 603, top horizontal drive shaft 604, stainless steel frame 605, hub 606, expansion sleeve 607, steel strand 608, water-blocking baffle 609. Pollutant monitoring system 7, sampling port 701, pollutant sensor 702, pollutant data processor 703, display 704, sensor deployment port 705; Camera system 8, high-definition camera 801, computer 802, blackout curtain 803, lighting panel 804, LED light strip 805. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0020] like Figures 1 to 7 As shown, the present invention provides an experimental device for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice gate-controlled rivers flowing into the sea. The device includes a simulated water tank 1, a land-based surface-to-ground runoff simulation system 2, a pollutant simulation system 3, a simulated sluice gate system 4, a nonlinear tide simulation system 5, a tide-gate linkage system 6, a pollutant monitoring system 7, and a camera system 8.

[0021] The simulated water tank 1 is placed vertically, with a length of 350cm, a width of 10cm, and a height of 70cm. The front of the simulated water tank 1 is a transparent tempered glass plate 101, and the back is a metal plate 102. The interior of the simulated water tank 1 is divided from left to right by two fully permeable partition plates 103 into a terrestrial surface-to-groundwater runoff generation zone 110, a gate-controlled river-coastal aquifer simulation zone 111, and a nonlinear tidal signal generation zone 112. The fully permeable partition plate 103 consists of a perforated acrylic plate 104 and a mesh screen 105. The terrestrial surface-to-groundwater runoff generation zone 110 is 10cm long and is connected to the terrestrial surface-to-groundwater runoff simulation system 2 through one surface inlet 106 and one underground inlet 107. The gate-controlled river-coastal aquifer simulation zone 111 is filled with white quartz sand with a particle size of d. 50 =0.2mm, d 90 / d 10 =2.5. The saturated hydraulic conductivity of the sand used in this invention was determined to be 4.65 × 10⁻³ m / s and the porosity to be 0.45 by the constant head method. The nonlinear tidal signal generation zone 112 is 35 cm long and is connected to the nonlinear tidal simulation system 5 on the right side through a small-diameter water tank inlet / outlet 108 and a large-diameter water tank inlet / outlet 109.

[0022] The terrestrial surface-to-subsurface runoff simulation system 2 is located on the left side of the simulated water tank 1, and mainly consists of two parts: a surface water simulation system 201 and a terrestrial subsurface recharge system 202. The surface water simulation system 201 includes a surface water storage tank 203, a high-flow-rate variable frequency pump 204, a water delivery pipeline 205, and a platform 206. The surface water storage tank 203 is placed on the surface of the platform 206. The surface water storage tank 203 is a five-sided impermeable stainless steel box structure, 25cm long, 25cm wide, and 35cm high, filled with deionized water. The inlet of the high-flow-rate variable frequency pump 204 is connected to the surface water storage tank 203 via a pipe, and the outlet is directly connected to the surface water inlet 106 of the simulated water tank 1 via the water delivery pipeline 205. This system directly controls the water flow injected into the river area of ​​the simulated water tank 1 by adjusting the speed or power of the high-flow-rate variable frequency pump 204. The pump's maximum flow rate is designed to be 100 times that of a groundwater peristaltic pump, enabling it to cover a wide range of flow variations from dry to flood seasons. This allows for direct regulation of river volume and velocity through flow rate adjustments, simulating surface runoff processes under different hydrological conditions. The terrestrial underground recharge system 202 includes a groundwater storage tank 207, a BW100 peristaltic pump 208, and a silicone transparent hose 209. The groundwater storage tank 207 is placed on the ground and is a five-sided impermeable stainless steel box structure, 20cm long, 20cm wide, and 30cm high, filled with deionized water. This tank is connected to the inlet of the BW100 peristaltic pump 208 via the silicone transparent hose 209, and the outlet of the peristaltic pump 208 is connected to the underground aquifer inlet 107 on the left side of the simulated water tank 1 via the silicone transparent hose 209. Using a BW100 peristaltic pump 208 as a power source, the flow rate is precisely controlled by adjusting the speed of the peristaltic pump. Deionized water is injected into the underground aquifer area of ​​the simulated water tank 1 through a silicone transparent hose 209, thereby simulating the lateral runoff recharge process of groundwater.

[0023] The pollutant simulation system 3 aims to achieve targeted and quantitative input of multi-source, multi-type pollutants from underground aquifers and surface rivers. It mainly consists of a first standard solution tank 301, a second standard solution tank 302, a third standard solution tank 303, a first BW100 peristaltic pump 304, a second BW100 peristaltic pump 305, a third BW100 peristaltic pump 306, a pollutant injection probe 307, and a silicone transparent tubing 209. The first standard solution tank 22, the second standard solution tank 23, and the third standard solution tank 24 are identical in size, all being five-sided waterproof stainless steel box structures measuring 10cm in length, 10cm in width, and 5cm in height. The first standard solution tank 301 contains a simulated organic pollutant (such as benzene) solution stained with methylene blue (MB) to simulate the release of organic oil pollutants. The second standard solution tank 302 contains a pollutant (such as ammonia nitrogen) solution stained with brilliant blue (BB) to simulate the release of nutrient-rich domestic sewage or agricultural non-point source pollution. The third standard solution tank 303 contains a high-concentration NaCl solution stained with Allura Red (AR) to simulate the high-salinity plume release of variable-density chemical pollutants. The first, second, and third standard solution tanks 301, 302, and 303 are connected to the inlets of the first, second, and third BW100 peristaltic pumps 304, 305, and 306, respectively, via silicone transparent tubing 209. The outlets of the three BW100 peristaltic pumps are connected to the pollutant injection probe 307 via silicone transparent tubing 209. The pollutant injection probe 307 is a hollow sphere with an inner diameter of 1 cm. Inserting the probe 307 into the sand layer inside the coastal aquifer of the simulated water tank 1 allows for the introduction of pollutants into any area of ​​the aquifer (upstream, midstream, near the seawater wedge interface, etc.) by adjusting the probe's depth and horizontal position. The pollutant injection probe 307 is fixed in the river area above the simulated water tank 1. By adjusting the position of the probe, pollutants can be injected into any cross section of the river.

[0024] The simulated sluice gate system 4 is located within the simulated coastal aquifer zone 111 of the sluice-controlled river flowing into the sea. It mainly consists of an upstream channel device 401, a gate chamber assembly 402, and a protective plate device 403. The upstream channel device 401 includes a variable permeability channel 4011, permeable holes 4012, stainless steel mesh 4013, an impermeable adjusting slide plate 4014, a stainless steel sliding rail 4015, and a flexible water-stop rubber sleeve 4016. The variable permeability channel 4011 is a U-shaped transparent acrylic channel with an open top, measuring 160cm in length, 10cm in width, and 5cm in height. The channel 4011 has a number of evenly distributed permeable holes 4012 with a diameter of 0.5cm, spaced 2cm apart. The inner wall of the channel is lined with a 300-mesh stainless steel mesh 4013 to prevent sediment loss. The impermeable adjusting slide plate 4014 is an opaque acrylic plate 10cm wide and 0.5cm thick. Its length is adjustable according to experimental requirements, ranging from 40cm to 100cm. The impermeable adjusting slide plate 4014 is tightly attached to the outer side of the bottom of the channel body and is connected to the channel body via two stainless steel slide rails 4015 installed at the bottom of the channel body. By changing the length of the slide plate covering the permeable holes 4014, the permeable area of ​​the channel above the gate can be precisely controlled. The end of the channel body 4011 is sealed to the gate chamber assembly 402 via a flexible water-stop rubber sleeve 4016. The flexible water-stop rubber sleeve 4016 is 10cm long, 3cm thick, and 20cm high. It is hollow and made of high-elasticity EPDM rubber. By adjusting the head end of the channel body 4011, the inclination angle of the channel body 4011 relative to the horizontal plane can be adjusted from 0° to 15°. This flexible connection method allows the channel body to deform during the adjustment of the inclination angle without compromising water tightness. The gate chamber assembly 402 is located at the downstream end of the river channel 4011 and includes the gate pier body 4021 and the gate guide groove 4022. The gate pier body 4021 is a solid acrylic block with a length of 12cm, a width of 10cm, and a height of 25cm. It has an 8cm wide flow channel in the center. The gate pier body 4021 has a standard flange interface 4023 on the right side. The gate guide groove 4022 is embedded in the center of the inner side of the gate pier body 4021, with a width of 1.2cm and a depth of 1cm. It is equipped with double rubber sealing strips 4024. The porous energy dissipation apron plate 403 is connected to the downstream side of the gate chamber assembly. It is an acrylic plate with a length of 20cm, a width of 10cm, and a thickness of 1.5cm. The surface is distributed with several staggered trapezoidal protrusions 4031 and energy dissipation holes 4032. The trapezoidal protrusions 4031 are 0.5cm high, and the energy dissipation holes 4032 are 0.8cm in diameter. The plate is directly fixed to the flange interface 4023 on the downstream side of the gate pier body 4021 by bolts 4033. The surface roughness of the plate and the structure of the energy dissipation holes 4032 simulate the energy dissipation and anti-scour function of the apron in actual engineering.

[0025] The nonlinear tidal simulation system 5 mainly consists of a first water pump 501, a second water pump 502, a flow regulating valve 503, a horizontal main gear disk 504, an input vertical gear 505, an input drive shaft 506, a drive motor 507, a transformer signal generator 508, a simulated seawater tank 509, a water level sensor 510, and a main controller 511. It aims to construct a highly realistic tidal environment within the main water tank by precisely controlling the difference between the inlet and outlet flow rates. The simulated seawater tank 509 is a five-sided impermeable stainless steel tank, 50cm long, 50cm wide, and 40cm high, placed on the ground. The first water pump 501 is a low-voltage DC variable frequency submersible pump. As a constant flow inlet pump, the first water pump 501 is connected to the inlet / outlet 108 of the small-diameter water tank via a water delivery pipe, injecting water into the main water tank at a constant flow rate of 1.2 m³ / h. The second water pump 502 is a self-priming centrifugal water pump. Installed at the drain end as an active forced-flow pump, its rated pumping flow rate of 3 m³ / h is designed to be 2.5 times the constant flow rate of the first water pump, ensuring the system has the ability to rapidly lower the water level during low tide. The inlet of the second water pump 502 is connected to the flow regulating valve 503 via a water supply pipe, and its outlet is connected back to the simulated seawater tank 509 via a water supply pipe, forming a closed-loop water circuit. The flow regulating valve 503 is installed on the pipeline between the inlet / outlet 109 of the large-diameter water tank and the second water pump 502, used to precisely control the actual pumping volume of the second water pump 502. The valve body is a DN32 stainless steel flange gate valve, with its core control mechanism located at the top of the valve body. A horizontal main gear disc 504 is horizontally mounted on the top of the valve stem of the flow regulating valve 503, replacing the traditional handwheel. The horizontal main gear disc 504 is made of carbon steel with a diameter of 10 cm and a thickness of 1 cm, and its outer circumference is equipped with standard module teeth. The input vertical gear 505 is located to the left of the horizontal main gear disk 504 and meshes perpendicularly with it. The input vertical gear 505 has a diameter of 0.12m. The input drive shaft 506 is a solid stainless steel rod with a diameter of 5cm and a length of 15cm. One end is connected to the input vertical gear 505, and the other end is connected to the drive motor 507 via a coupling. The drive motor 507 is a low-speed, high-torque DC geared motor with a rated voltage of 12V and a speed range of 0~30rpm. It is installed on the upper right side of the main water tank and is connected to the transformer signal generator 508 via wires. The transformer signal generator 507 receives instructions from the main controller and is installed on the right side of the main water tank. By changing the voltage polarity and magnitude, it controls the forward and reverse rotation and speed of the drive motor 507, thereby driving the input vertical gear 505 to rotate, which in turn drives the horizontal main gear disk 504 to rotate, thus adjusting the valve opening to control the drainage flow. The drive motor 507 is connected to the transformer signal generator 508 via wires. The transformer signal generator 508 has a built-in main controller 511, which incorporates a reverse hydrodynamic model algorithm and can generate a target tidal level curve based on user input. It automatically calculates the voltage signal required to drive motor 507.

[0026] The nonlinear tidal simulation system 5 adopts the principle of constant inflow-variable outflow difference integral tidal water level generation, which differs from existing technologies that rely on physical lifting methods such as gantry-overflow weir raising or piston reciprocating. Its basic principle is as follows: within the nonlinear tidal signal generation zone 112 of the simulated water tank, the first water pump 501 operates at a constant flow rate... Water is continuously injected, and the second water pump 502 adjusts the flow rate via the flow regulating valve 503. Drain the water. Water level in the tank. The change depends on the integral effect of the difference between the inflow and outflow rates over time. Consider the tank as having a cross-sectional area of... For a finite volume of water, the change in water level follows the mass conservation equation: (1) Among them, drainage flow Controlled by flow regulating valve 503: (2) in For the comprehensive flow characteristic function of the pump-valve system, This is the valve rotation angle; this characteristic function The point at which the QH characteristic curve of the second water pump 502 intersects with the valve throttling characteristic determines the relationship between the valve opening and the flow rate under constant speed pump drive.

[0027] Characteristic function It is inherently nonlinear, and its nonlinearity stems from the following three aspects: (a) the effective water passage area of ​​the gate valve. With angle The relationship between them is usually non-linear (equal percentage characteristic or quick-opening characteristic); (b) the QH curve of a centrifugal pump is a non-linear decreasing curve, and different valve openings correspond to different pump operating points; (c) the local head loss in the pipeline is quadratic with the flow rate. The superposition of the above factors makes This cannot be described by a simple linear proportional relationship and must be determined through system calibration experiments. After initial use or replacement of valve components, the system needs to be calibrated to establish the pump-valve system characteristic curve and motor parameters. Pump-valve system characteristic curve calibration method: Keep the second water pump 502 running at a constant speed, while simultaneously turning on the first water pump 501 and the external water supply to maintain a basically constant water level in the tank. Rotate the valve in equal angular steps (5° per step), at each angle... After the flow rate stabilizes, the steady-state drainage flow rate is recorded using a flow meter at the outlet. Establish the comprehensive characteristic function of the pump-valve system: (3) Fit the measurement data to a polynomial Alternatively, it can be stored as a discrete lookup table, and its inverse function can be obtained. Used for reverse engineering.

[0028] Substituting formula (2) into formula (1), we obtain the result regarding the water level. Nonlinear ordinary differential equations: (4) because It is a non-linear function, and the target tidal waveform Complex time series containing multiple frequencies, asymmetry, and non-stationarity still require inverse solutions from target water levels to control signals through nonlinear function inversion, and cannot be achieved through simple linear calculations.

[0029] like Figure 8 and Figure 9 As shown, the transformer signal generator 508 has a built-in main controller 511, which incorporates a reverse hydrodynamic model algorithm and can generate a target tidal level curve based on user input. Automatically calculate the voltage signal required to drive motor 507. Its reverse solution process includes the following five steps: Step 1: Target tidal waveform synthesis; The main controller 511 supports the following three tidal waveform input modes: (a) Harmonic constant input mode: The user inputs the harmonic constant of the main tidal constituents and the amplitude. ,frequency Phase The system automatically overlays and generates the target tidal curve: (5) in The average water level For the first Each tidal phase, N represents the total number of tidal phases, encompassing tidal components such as M2 (major lunar semi-diurnal tidal phase), S2 (major solar semi-diurnal tidal phase), K1 (solar and lunar declination diurnal tidal phase), and O1 (major lunar diurnal tidal phase), as well as nonlinear high-frequency components such as shallow water tidal phases MS4 and M4. (b) Measured data import mode: Directly import measured tide level time series data; (c) Custom composite mode: Based on the harmonic tide, a user-defined non-periodic signal is superimposed, including storm surge pulse signal, shallow water deformation factor and random disturbance term, to generate a non-linear irregular tidal waveform containing semi-diurnal tide, shallow water tide, storm surge and their superposition.

[0030] Step 2: Calculate the required drainage flow rate; For the target water level curve By performing time differentiation and combining it with formula (1), the required drainage flow rate at each moment can be calculated: (6) Meet key design constraints: When Take the largest positive value (the moment of fastest tide rise). When the minimum value is reached, the valve tends to close, and the water body maintains a constant inflow. Accumulation increases under the influence of the action; when Take the largest negative value (the moment when the tide recedes the fastest). The maximum value is taken, at which point the valve is fully opened for rapid drainage. The system design specifies the rated flow rate of the second water pump 502. This ensures sufficient drainage capacity even under maximum ebb tide conditions, while The continuous injection ensured the maximum tidal rate. The physical feasibility of (the valve does not require reverse water injection).

[0031] Step 3: Calculate the required valve opening angle; Substituting formula (6) into the inverse function of formula (2), we can obtain the required valve rotation angle:

[0032] (7) in The comprehensive flow characteristic function of the pump-valve system The inverse function. This inverse function is pre-established through system calibration experiments (see part of formula (3) for details), because It is nonlinear, and its inverse function Similarly, it is non-linear, meaning that the change in valve angle corresponding to a constant change in drainage flow differs across different operating ranges. For example, when the valve is near the fully closed or fully open position, the flow rate is less sensitive to angle (an inherent non-linear characteristic of gate valves), while the sensitivity is higher in the intermediate opening range. Therefore, even with the required flow rate... It varies sinusoidally, and the required angle It also exhibits a non-sinusoidal waveform. This non-linear mapping is the fundamental technical reason why this system must use an inverse model to solve the problem instead of simple linear proportional control.

[0033] Step 4: Calculate the required motor angular velocity; For the obtained By performing the time derivative, the required valve rotation angular velocity is obtained: (8) Considering gear ratio ,in To input the pitch circle radius of the vertical gear 505, Given the pitch circle radius of the horizontal main gear disk 504, the required angular velocity of the motor is: (9) Step 5: Generating the drive voltage signal; According to the electromechanical characteristic equation of a DC motor, the relationship between the motor angular velocity and the terminal voltage is as follows: (10) in This is the motor speed constant, which can be obtained by purchasing the motor instruction manual; The armature resistance can be obtained by purchasing the motor instruction manual; This represents the load current. Under low-speed, high-torque conditions, the armature resistance voltage drop is relatively small, approximately: (11) Drive motor 507 according to voltage signal The polarity controls the rotation direction (forward valve opening / reverse valve closing), and the rotation speed is controlled according to the voltage amplitude, thereby accurately tracking the required valve angle trajectory. .

[0034] Combining steps one through five, the main controller 511 built into the transformer signal generator 508 performs the following reverse chain solution:

[0035] In the above five-level reverse solution chain, the third step ( This involves the inversion of the nonlinear characteristic function of the pump-valve system and is the core nonlinear link in the entire chain. The nonlinear characteristics of this link affect the output voltage signal. With target water level There is no simple proportional, differential, or any linear mapping relationship between them, and they can only be correctly solved through the complete inverse hydrodynamic model described above.

[0036] The water level sensor 510 is a miniature pressure water level gauge, installed at the bottom of the water tank in the nonlinear tidal signal generation area 112, to collect real-time data on the actual water level. The data is then transmitted to the main controller 511. The main controller 511 compares the actual water level with the target water level and calculates the water level deviation. (12) The pre-calculated voltage signal is corrected in real time based on the PID (proportional-integral-derivative) feedback control algorithm. (13) in , , These are the proportional coefficient, integral coefficient, and derivative coefficient, respectively, determined through initial system debugging. This feedback correction mechanism compensates for the following error sources: (a) the pump-valve system characteristic function. (a) Slow drift caused by valve wear; (b) angular lag caused by gear transmission clearance and friction; (c) slight fluctuations in the actual inflow of the first water pump 501; (d) leakage deviation caused by changes in the sealing of pipeline connections. Through a dual-loop control architecture of feedforward (inverse model pre-calculation) + feedback (PID real-time correction), the system can maintain high-precision target waveform tracking under long-term operating conditions, with the water level tracking error controlled within ±2mm.

[0037] This invention proposes a constant inflow-variable outflow difference integral nonlinear tidal water level generation method. The system employs a pump-driven active drainage scheme to ensure consistent control capability across the entire tidal range. Its core lies in establishing a five-level inverse solution chain from the target tidal water level curve to the motor drive voltage signal. Through the inverse inversion of the nonlinear characteristic function of the pump-valve system, arbitrarily complex tidal waveforms are transformed into precise time-varying voltage control signals. Combining real-time feedback from the water level sensor and a PID correction algorithm to form a feedforward feedback dual-loop control architecture, high-precision indoor reproduction of nonlinear irregular tidal waveforms is achieved, overcoming the shortcomings of existing technologies that can only simulate simple sinusoidal tides and lose control capability at low water levels.

[0038] The tidal-gate linkage system 6 utilizes the rotational motion of the horizontal main gear disk 504 from the nonlinear tidal simulation system 5 as a power source, synchronously driving the raising and lowering of the sluice gate through multi-stage gear transmission. The system mainly consists of a vertical drive shaft 601, a horizontal driven gear disc 602, a variable-speed vertical gear set 603, a top horizontal drive shaft 604, a stainless steel frame 605, a hub 606, a shrink sleeve 607, steel strands 608, and a water-blocking baffle 609. The vertical drive shaft 601 is a solid 304 stainless steel shaft with a diameter of 6mm and a length of 45cm. Its bottom end is coaxially connected to the central axis of the horizontal main gear disk 504 via a coupling, and the top end is fixed to the horizontal driven gear disc 602. The horizontal driven gear disc 602 has a diameter of 10cm and is designed as a bevel gear disc structure. The variable-speed vertical gear set 603 is located to the right of the horizontal driven gear disc 602 and contains four standard bevel gears with different modules and numbers of teeth. These gears are designed to be detachable and replaceable. Each time, one gear is selected to mesh perpendicularly with the horizontal driven gear turntable 602 according to experimental needs, achieving a 90-degree reversal and setting a mechanical transmission ratio of 1:1 to 1:3. The stainless steel frame 605 is welded from 30mm × 30mm square tubing and spans the 10cm wide opening of the main water tank, with a height of 80cm to allow space for gate lifting. The top transverse drive shaft 604 is horizontally mounted on top of the stainless steel frame 605, with a shaft length of 300cm and a diameter of 5cm. One end extends out of the bracket and connects to the variable speed vertical gear set 603, while the other end is suspended directly above the center of the main water tank and connects to the hub 606 of the sluice gate. The hub 606 is a 10cm diameter aluminum alloy winding reel, mounted on the top transverse drive shaft 604 via a type expansion sleeve 607. When the expansion sleeve 607 is loosened, the hub can slide axially to precisely align with the center line of the gate pier body 4021. After tightening the high-strength bolts of the expansion sleeve 607, the huge friction force generated by the conical surface locks the hub 606 and the transverse drive shaft 604 in place, allowing them to rotate synchronously with the shaft. The hub 606 is connected to the water-blocking baffle 609 by steel strands 608 wound in the spiral grooves on the surface. The steel strands 608 have a diameter of 1.5mm and are made of 316 stainless steel. The water-blocking baffle 609 is a transparent acrylic plate with dimensions of 9.8cm wide, 22cm high, and 10mm thick. A precision fit gap of 1mm on each side is reserved between this width (9.8cm) and the inner width of the main water channel (10cm), ensuring smooth gate sliding and effectively blocking water in conjunction with the rubber sealing strips on the edges. When the tide simulation system 5 adjusts the valve to change the water level, the rotational motion of the valve is transmitted to the top transverse transmission shaft 604 via the vertical transmission shaft 601, which in turn drives the hub 606 to rotate. During low tide, the flow regulating valve 503 opens and drives the water-blocking baffle 609 to rise (i.e., the gate opens to release water), and during high tide, the flow regulating valve 503 closes and drives the water-blocking baffle 609 to fall (i.e., the gate closes to store water).By replacing different gears in the variable speed vertical gear set 603, the mechanical transmission ratio of the system can be changed, thereby obtaining different gate lifting and lowering amplitudes under the same tidal water level change amplitude, simulating the gate response characteristics under different water conservancy scheduling rules.

[0039] The pollutant monitoring system 7 consists of a sampling port 701, a pollutant sensor 702, a pollutant data processor 703, a display 704, and a sensor mounting hole 705. The sampling port 701 is located on the back of the simulated water tank 1, and is filled with white silicone to prevent water leakage and facilitate needle puncture for sampling. The pollutant sensor 702 is installed in the sensor mounting hole 705 on the back of the simulated water tank 1. One end of the pollutant data processor 703 is connected to the pollutant sensor 702, and the other end is connected to the display 704. The pollutant sensors 702 employ a non-uniform deployment strategy. In this embodiment, 20 sensor holes in 8 rows are arranged at 10cm, 30cm, 45cm, 50cm, and 55cm from the bottom of the simulated water tank 1. The lateral positions of the pollutant sensors 702 are 40cm, 100cm, 140cm, 180cm, 190cm, 210cm, 250cm, and 290cm from the left fully permeable partition plate 103. Among them, the three rows of nine pollutant sensors 702 at 180cm, 190cm, and 210cm from the left fully permeable partition plate 103 constitute a high-density monitoring area. By increasing the deployment density with a lateral spacing of approximately 15cm, the rapid changes in pollutant concentration near the gate and partition plate in the simulated water tank 1 can be monitored at high frequency and with precision, especially the pollutant migration and transformation mechanism in the area most affected by the gate-controlled river. The sensors at the remaining positions constitute the background and diffusion monitoring area. The pollutant data processor 703 records this data in real time and visualizes the high-frequency data change curves through the display 704, enabling in-situ monitoring of pollutants in coastal reservoirs and adjacent aquifers.

[0040] The high-resolution imaging device 8 consists of a high-definition camera 801, a desktop computer 802, a blackout curtain 803, and an illumination panel 804. The desktop computer 802 is connected to the high-definition camera 801 and uses software to adjust the shooting frequency and duration of the high-definition camera 801. The high-definition camera 801 is positioned in front of the simulated water tank 1, and the illumination panel 804 is located directly above the simulated water tank 1, consisting of evenly distributed LED light strips 805. To create a darkroom environment, the high-definition camera 801, the illumination panel 804, and the simulated water tank 1 are surrounded by a blackout curtain 803 that is 4 meters long and 2 meters high.

[0041] The present invention discloses an experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea. The method includes the following steps: S1. Prepare experimental sand and simulated seawater: Sieve white quartz sand according to experimental requirements, with a particle size of d. 50 =0.2mm, d 90 / d 10 =2.5; After sieving, the sand was washed multiple times with deionized water and placed in a water-saturated bucket for later use to ensure that air bubbles inside the quartz sand were completely expelled. The saturated hydraulic conductivity of the experimental sand was determined to be 4.65 × 10⁻³ m / s and the porosity to be 0.45 by the constant head method. The simulated seawater in simulated seawater tank 509 was prepared by mixing deionized water and industrial salt in a certain mass ratio, with the salinity set at 35 g / L and the density at 1024 kg / m³. It was stirred thoroughly until completely dissolved before use. S2. Arrange experimental sand, channel device, and gate chamber components: Fill the gate-controlled river-coastal aquifer simulation zone 111 with white quartz sand using a saturated water method, ensuring the water level is always at least 10cm above the sand surface during filling. Fill the sand in layers while adding water, gently tapping the tank wall with a glass rod every 5cm to remove air bubbles, until the predetermined height is reached. According to the experimental design, install the gate-controlled river channel device 401 inside the gate-controlled river-coastal aquifer simulation zone 111. Fix the variable permeability channel 4011 above the simulation tank 1 using an angle adjustment bracket 4013. 1. The bottom permeable hole 4015 faces downward and contacts the aquifer. Adjust the position of the impermeable regulating slide plate 4012 to control the length of the permeable area from 40cm to 100cm according to the experimental requirements. Adjust the inclination angle of the channel body 4011. Install the gate chamber assembly 402 at the downstream end of the channel body 4011. Seal the gate pier body 4021 to the end of the channel body 4011 with a flexible water-stop rubber sleeve 4016 through the flange interface 4023 to ensure that the connection is leak-proof. Fix the porous energy dissipation abutment plate 403 to the flange interface 4023 on the downstream side of the gate pier body 4021 with bolts 4033. S3. Debug the land-based surface-to-ground runoff simulation system and the pollutant simulation system: Fill the surface water storage tank 203 and the groundwater storage tank 207 with deionized water to 80% of their volumes; prepare standard pollutant solutions in the first standard solution tank 301, the second standard solution tank 302, and the third standard solution tank 303 respectively. Prepare a 50 mg / L methylene blue MB solution in the first standard solution tank 301 to simulate organic pollutants, a 100 mg / L brilliant blue BB solution in the second standard solution tank 302 to simulate nutrient pollutants, and a 100 g / L Allura Red AR solution in the third standard solution tank 303 to simulate high-salinity pollutants; insert the pollutant injection probe 307 into the simulation tank 1, and adjust the position of the probe tip to near the upstream, midstream, or downstream interface of the aquifer according to the experimental design. S4. Debugging the nonlinear tidal simulation system and the tidal-gate linkage system: Inject prepared simulated seawater into the simulated seawater tank 509 to 90% of its volume. Start the first water pump 501 and adjust its flow rate to a constant value of 1.2 m³ / h; start the second water pump 502, preset the nonlinear tidal voltage signal V(t) in the transformer signal generator 508, start the drive motor 507, the drive motor 507 rotates forward and reverse according to the voltage signal and drives the input vertical gear 505 to rotate, which in turn causes the horizontal main gear disk 504 to rotate, driving the flow regulating valve 503 to change the opening degree through gear meshing, thus changing the actual drainage flow of the second water pump 502; observe whether the water level in the nonlinear tidal signal generation area 112 shows periodic rise and fall, and ensure that the water level change amplitude meets the design requirements; select the appropriate gear in the variable speed vertical gear set 603 according to the experimental requirements. The appropriate gear meshes with the horizontal driven gear turntable 602, and the mechanical transmission ratio is set to 1:1, 1:2 or 1:3; one end of the steel strand 608 is fixed in the spiral groove of the hub 606, and the other end is connected to the top of the water-blocking baffle 609. The length of the steel strand 608 is adjusted so that the lower edge of the water-blocking baffle 609 is 1cm away from the bottom of the river channel 4011; the transformer signal generator 508 is started, the tidal waveform parameters are set, and the tidal water level change and the gate lifting action can be synchronized to verify the linkage logic of the flow regulating valve 503 opening and the water-blocking baffle 609 rising (gate opening) during low tide, and the flow regulating valve 503 closing and the water-blocking baffle 609 falling (gate closing) during high tide; S5. Deployment of the pollutant monitoring and camera system: According to the experimental design, install pollutant sensor 702 in the sensor mounting hole 705 on the back of the simulated water tank 1; lead the cable of pollutant sensor 702 out through the wiring hole on the back of the simulated water tank 1 and connect it to pollutant data processor 703; connect pollutant data processor 703 to display 704, set the data acquisition frequency to once every 5 seconds, and display the pollutant concentration change curve of each monitoring point in real time; set up a high-definition camera 801 1.5 meters in front of the simulated water tank 1, and adjust the focus to make the entire gate control... The simulated aquifer zone 111 of the Haihe River-Coastal Aquifer is within the field of view; lighting panels 804 are evenly arranged directly above the simulated water tank 1; a high-definition camera 801 is connected to a desktop computer 802 via a data cable, camera control software is installed, and the shooting mode is set to interval timed shooting with a time interval of 10 seconds; a light-blocking curtain 803 with a length of 4 meters and a height of 2 meters is erected around the simulated water tank 1 to surround the high-definition camera 801, lighting panels 804 and simulated water tank 1, creating a darkroom environment to eliminate external light interference and ensure that the images of the dyed pollutants captured have clear contrast; S6. Run the experiment and monitor the pollutant migration and transformation process: Turn on the terrestrial surface-subsurface runoff simulation system 2, inject the designed flow rate of surface runoff into the river channel 4011 through the high-flow-rate variable frequency pump 204, and inject the designed flow rate of subsurface runoff into the aquifer inlet 107 through the BW100 peristaltic pump 208 to simulate the terrestrial hydrological process; turn on the nonlinear tidal simulation system 5, start the first pump 501 and the second pump 502, and control the drive motor 507 through the transformer signal generator 508 to generate the designed nonlinear tidal waveform. The small-diameter flume inlet / outlet 108 and the large-diameter flume inlet / outlet 109 work simultaneously to form periodic water level fluctuations in the nonlinear tidal signal generation zone 112; after the river flow, subsurface runoff and tidal waveform have all stabilized for 10 minutes... The pollutant simulation system 3 is started. According to the experimental design, the first BW100 peristaltic pump 304, the second BW100 peristaltic pump 305, or the third BW100 peristaltic pump 306 are selected. The pollutant solution labeled with methylene blue (MB), brilliant blue (BB), or allura red (AR) is injected into the aquifer or the designed location of the river channel through the pollutant injection probe 307. During the experiment, water samples at different depths and locations of the aquifer are collected periodically through the sampling port 701 on the back of the simulated water tank 1 using a syringe. The samples are collected once every 2 hours. The experiment is run continuously for 20 to 40 hours to record the complete pollutant injection-migration-dilution-transformation process and to capture the coupled effects of tidal cycle (high tide-low tide), gate control cycle (opening-closing), and river flow change (dry water-flood) on the pollutant transport pattern. Step S6 involves running the experiment and establishing a parameter monitoring system. This includes running the experiment and monitoring the pollutant migration and transformation process, assigning unified symbols to the physical quantities collected throughout the experiment. Specifically, this includes the following sub-steps: S6.1. Reference State Calibration: Without activating the tidal system and gate linkage system, after the water level in the simulated water tank 1 stabilizes, record the initial reference water level. (Unit: cm) and background concentration at each monitoring point (Unit: mg / L), where The spatial coordinates of sensor 702 in the simulated zone 111 of the sluice-controlled river-coastal aquifer. The horizontal distance from the landside boundary ( ), The vertical height from the bottom of the tank ( ).

[0042] S6.2. Start the terrestrial surface-subsurface runoff simulation system 2 and record the input flux: Start the terrestrial surface-subsurface runoff simulation system 2, and inject the designed flow rate of surface runoff into the river channel 4011 through the high-flow-rate variable frequency pump 204, and record the surface runoff input flow rate. (Unit: mL / min); Groundwater recharge flow rate is recorded as the designed flow rate is injected into the aquifer inlet 107 using a BW100 peristaltic pump 208. (Unit: mL / min). The next step will proceed after the river flow, groundwater runoff, and aquifer water level have stabilized.

[0043] S6.3. Start the nonlinear tidal simulation system 5 and record the tidal water level time series: Start the first water pump 501 and the second water pump 502, and drive the motor 507 through the transformer signal generator 508 to generate a nonlinear tidal waveform. Deploy the water level sensor 510 in the nonlinear tidal signal generation area 112 to record the real-time tidal water level time series. (Unit: cm)

[0044] S6.4. Start the tidal gate linkage system 6 and record the gate status parameters: record the gear transmission ratio set for this experiment. (Range range is 1:1, 1:2, or 1:3), activate the tidal-gate linkage system 6. Measure the displacement of the baffle plate 609 and record the gate opening time series in real time. (Unit: cm), and calculate the gate state function accordingly: (14) Simultaneously record the moment when the gate switches from closed to open during each tidal cycle. and the moment of switching from on to off Calculate the gate opening duration in a single cycle. .

[0045] S6.5. Start the pollutant simulation system 3 and record the injection parameters: Select and start the first BW100 peristaltic pump 304 (or 305, 306) according to the experimental design, insert the pollutant probe 307 into the simulation water tank 1 at the designed position, and record the pollutant injection flow rate. (Unit: mL / min) and injection concentration (Unit: mg / L), injection location coordinates are The injection concentrations of the three tracers were as follows: methylene blue (MB) solution concentration... mg / L, Brilliant Blue (BB) solution concentration mg / L, Allura Red (AR) labeled NaCl solution concentration g / L.

[0046] S6.6. Multi-parameter collaborative continuous monitoring: run the experiment continuously for 20 to 24 hours, and collect the following parameter quantitative data simultaneously: River water level: Time series of water levels in 4011 inlet channels of variable permeability river channel. (cm); Pollutant concentration field: Sensor 702 collects pollutant concentrations at each monitoring point. (Unit: mg / L), the pollutant data processor 703 and display 704 display the concentration-time curve in real time; the spatial average concentration of the sensors in the river channel is calculated respectively. Spatial average concentration of sensors within the aquifer ; Salinity distribution: The conductivity of each monitoring point is collected synchronously using sensor 702 and converted into salinity. (Unit: g / L), used to identify the location of the brackish water interface; Optical images of pollutant plumes: High-resolution camera 801 captured frontal images of the aquifer simulation zone 111 at 10-second intervals to obtain the spatial distribution grayscale field of the stained pollutants. Convert grayscale values ​​into a two-dimensional concentration field Pollutant concentrations collected by sensor 702 Concentration field obtained by correcting optical images .

[0047] S6.7. Estimation of Key Fluxes: During the experimental operation, based on the water level data collected in step S6.5, the following key exchange fluxes are estimated online: River-aquifer infiltration exchange flow: Because the river water level is always higher than the aquifer groundwater level, river water continuously replenishes the aquifer through unidirectional downward infiltration of the riverbed medium. It is always a positive value. According to Darcy's law, the vertical infiltration exchange flow from the river channel to the aquifer is: (15) in, The riverbed permeability coefficient is determined by the constant head test in step S1; The effective infiltration area (unit: cm²) between the bottom of the river channel and the aquifer is determined by the geometric dimensions of the bottom of the river channel 4011. The thickness of the permeable layer in the riverbed (unit: cm) is the thickness of the medium between the bottom of the river channel and the top of the aquifer, which is determined by the filling thickness during model construction. Here is the elevation of the riverbed (unit: cm), and here are the known parameters of the model's geometry. The water level of the 4011 inland river channel was changed to a permeable channel body; The gate discharge flow rate is calculated according to the gate hydraulic formula: (16) in, The gate's net width is 10cm. and Recorded in real time by step S6.4. Data is collected in real time as per step S6.5. The real-time tidal water level downstream of the sluice gate is recorded by water level sensor 510, unit: cm. It is the acceleration due to gravity; S7. Stop the experiment, data processing, and quantitative analysis of gated pollutant migration and transformation, specifically including the following sub-steps: After the experiment, shut down the pollutant simulation system 3 and all subsystems, organize all the data collected in step S6, and establish a quantitative analysis model of pollutant migration and transformation in the coastal aquifer under the influence of the sluice-controlled river flowing into the sea according to the following sub-steps: Experimental data preprocessing and time alignment: Unifying all sensor data from step S6 to the same time base. For concentration time series Perform median filtering for noise reduction; Establish a set of mass conservation equations for a coupled two-region system of gate-controlled river channels and coastal aquifers: The sluice-controlled river-coastal aquifer system is divided into two coupled subsystems: the channel region and the coastal aquifer region. Pollutant mass conservation equations are established for each subsystem. River channel mass conservation equation: (17) Mass conservation equation for coastal aquifer regions: (18) in The volume of the river channel water is determined by the geometric dimensions of the 4011 channel body and... calculate; The volume of the aquifer is determined by the geometric dimensions of the aquifer simulation zone 111. The average pollutant concentration in the river channel is spatially averaged by the pollution sensor 702 in step S6.5; The average pollutant concentration in the aquifer is spatially averaged by the pollutant sensor 702 in step S6.5; The surface input flow rate is determined by the set value of the high-flow-rate variable frequency pump 204 in step S6.2; The pollutant concentration input to the surface is determined by the value prepared in the standard solution tank in step S6.5; The groundwater recharge flow rate is determined by the set value of the BW100 peristaltic pump 208 in step S6.2; The groundwater pollutant concentration is determined by the standard solution tank preparation value in step S6.5; The infiltration exchange flow rate between the river channel and the aquifer is calculated in real time using formula (15) and is always a positive value. The discharge flow rate of the gate is calculated in real time using formula (16); The gate state function is determined in real time by formula (14); The discharge flow from the aquifer to the sea is estimated by fitting the formula (18); The intrusion flow rate of seawater into the aquifer is estimated by fitting the formula (18); The concentration of seawater pollutants is determined by the known concentration of the seawater prepared in step S1; Porosity , The flow rate of pollutants injected into the river is determined by a peristaltic pump; The flow rate for injecting pollutants into the aquifer is determined by a peristaltic pump; The concentration of the injected contaminant is determined by the standard solution tank preparation value; The rate of change of pollutant mass in the river over time; The pollutant flux carried in by surface runoff, The flux of pollutants carried away by the aquifer is replenished by the infiltration of river water. The amount of pollutants discharged when the gate is opened. The flux of tracer pollutants injected into the river during the experiment; The rate of change of the mass of pollutants in the pore water of the aquifer over time. Porosity; The flux of pollutants carried by terrestrial groundwater replenishment. This refers to the flux of pollutants carried by river water as it infiltrates into the aquifer. This refers to the pollutant flux carried away by the aquifer as it discharges towards the sea. This refers to the flux of pollutants brought in by seawater intrusion into the aquifer. The flux of tracer pollutants injected into the aquifer during the experiment; This invention is achieved through The project achieves coupling between two subsystems: the river channel and the aquifer. The river channel is the source of pollutants (losing the flux), and the aquifer is the sink (gaining the flux). The gate state function... The total amount of pollutants entering the aquifer is indirectly regulated by controlling the discharge flow rate.

Claims

1. An experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, characterized in that, The system includes a simulation flume (1) divided from left to right by a fully permeable baffle (103) into a terrestrial surface-subsurface runoff generation zone (110), a gate-controlled river-coastal aquifer simulation zone (111), and a nonlinear tidal signal generation zone (112); a terrestrial surface-subsurface runoff simulation system (2) connected to the terrestrial surface-subsurface runoff generation zone and used to simulate the lateral runoff recharge process of groundwater; and a pollutant simulation system for the fixed-point and quantitative input of pollutants into the aquifer and surface river channels. (3) A simulated sluice gate system located in the simulated area of ​​the sluice-controlled river flowing into the sea and the coastal aquifer (4) A nonlinear tide simulation system connected to the nonlinear tide signal generation area (103) (5) A tide-gate linkage system for associating gates and tides (6) A pollutant monitoring system for in-situ monitoring of pollutants in coastal reservoirs and adjacent aquifers (7) A camera system for filming the migration and transformation process of pollutants in the coastal aquifer under the influence of the sluice-controlled river flowing into the sea during the experimental operation (8).

2. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 1, is characterized in that... The terrestrial surface-to-ground runoff simulation system (2) includes a surface water simulation system (201) and a terrestrial underground recharge system (202). The surface water simulation system (201) includes a platform (206), a surface water storage tank (203) located on the platform (206) and storing deionized water that simulates surface water, a high-flow-rate variable frequency pump (204) with its inlet connected to the surface water storage tank (203), and a connection between the outlet of the high-flow-rate variable frequency pump (204) and the terrestrial surface-to-ground runoff generation zone (110). The surface water inlet (106) of the land-based underground recharge system (202) includes a groundwater storage tank (207) storing deionized water that simulates groundwater, a BW100 peristaltic pump (208) whose inlet is connected to the groundwater storage tank (207) via a transparent hose (209), and a transparent hose (209) connecting the outlet of the BW100 peristaltic pump (208) to the inlet (107) of the underground aquifer of the land-based surface-underground runoff generation zone (110).

3. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 1, is characterized in that... The pollutant simulation system (3) includes a first standard solution tank (301) storing a first colored pollutant solution and used to simulate the release of organic oil pollutants, a second standard solution tank (302) storing a second colored pollutant and used to simulate the release of nutrient-rich domestic sewage or agricultural non-point source pollution, a third standard solution tank (303) storing a third colored pollutant and used to simulate the release of high-salinity plumes of variable-density chemical pollutants, a first BW100 peristaltic pump (304) with its inlet connected to the first standard solution tank (301), a second BW100 peristaltic pump (305) with its inlet connected to the second standard solution tank (302), a third BW100 peristaltic pump (306) with its inlet connected to the third standard solution tank (303), and a pollutant injection probe (307) inserted into the sand layer inside the coastal aquifer of the simulation tank (1).

4. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 1, is characterized in that... The simulated sluice gate system (4) includes, from left to right, a gate-upper channel device (401), a gate chamber assembly (402), and a porous energy-dissipating protective plate (403). The gate-upper channel device (401) includes a channel body (4011), permeable holes (4012) evenly distributed on the channel body (4011), a stainless steel mesh (4013) located on the inner wall of the channel body (4011), a stainless steel slide rail (4015) located at the bottom of the channel body (4011), an impermeable adjusting slide plate (4014) connected to the stainless steel slide rail (4015), and a section located on the channel body (4011). 11) A flexible water-stop rubber sleeve (4016) at the end and sealed to the gate chamber assembly (402); the gate chamber assembly (402) includes a gate pier body (4021) with a flow passage in the middle, a gate guide groove (4022) embedded in the center of the inner side of the gate pier body (4021), and a standard flange interface (4023) located on the right side of the gate pier body (4021). The porous energy dissipation plate (403) is connected to the standard flange interface (4023). The surface of the porous energy dissipation plate is distributed with several staggered trapezoidal protrusions (4031) and energy dissipation holes (4032).

5. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 1, is characterized in that... The nonlinear tidal simulation system (5) includes a simulated seawater tank (509), a first water pump (501) connected to the outlet of the simulated seawater tank (509) and acting as a constant flow water pump connected to the small-diameter inlet / outlet (108) of the simulated water tank (1) to inject water into the simulated water tank at a constant flow rate, a second water pump (502) whose inlet is connected to the large-diameter inlet / outlet (109) of the simulated water tank (1) via a water supply pipe and whose outlet is connected to the simulated seawater tank (509) via a water supply pipe and is used to simulate low tide drainage, and a pipeline installed between the large-diameter inlet / outlet (109) and the second water pump (502). The system comprises a flow regulating valve (503), a horizontal main gear disk (504) horizontally mounted on the top of the valve stem of the flow regulating valve (503), an input vertical gear (505) meshing with the horizontal main gear disk (504), an input drive shaft (506) coaxially arranged with the input vertical gear (505), a drive motor (507) with an output shaft connected to the input drive shaft (506), a water level sensor (510) for detecting water level, and a main controller (511) for controlling the drive motor (507) and having a built-in transformer signal generator (508). The main controller (511) controls the target tidal water level curve. The voltage signal of the control drive motor (507) is solved and transmitted to the drive motor (507) through the transformer signal generator (508).

6. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 5, is characterized in that... In the nonlinear tidal simulation system (5), the main controller (511) calculates the target tidal level curve. To solve for the voltage signal controlling the drive motor (507), the specific reverse solution is as follows: Within the nonlinear tidal signal generation zone (112) of the simulated water tank (1), the first water pump (501) operates at a constant flow rate. Water is continuously injected, and the second water pump (502) discharges water at the required flow rate via the flow regulating valve (503). The water body is drained, and the simulated water tank is considered to have a cross-sectional area of A limited volume of water, for the target water level curve Perform time differentiation to calculate the required drainage flow rate at each moment. The calculation formula is: ， Determine the required valve rotation angle: ， ， in The comprehensive flow characteristic function of the pump-valve system The inverse function of the pump-valve system's comprehensive flow characteristic function Established in advance through system calibration experiments; For the obtained By performing the time derivative, the required valve rotation angular velocity is obtained: ， Considering gear ratio , To input the pitch circle radius of the vertical gear (505), Given the pitch circle radius of the horizontal main gear disk (504), the required angular velocity of the motor is: ， According to the electromechanical characteristic equation of a DC motor, the relationship between the motor angular velocity and the terminal voltage is as follows: ， in Let be the motor speed constant. For armature resistance, This is the load current; The drive motor (507) is based on the voltage signal The polarity controls the direction of rotation, and the rotation speed is controlled according to the voltage amplitude; The water level sensor (510) collects the actual water level in real time. The data is transmitted to the main controller (511), which compares the actual water level with the target water level and calculates the water level deviation. ， The pre-calculated voltage signal is corrected in real time based on a PID feedback control algorithm. ， in , , These are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

7. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 5, is characterized in that... The tidal gate linkage system (6) includes a vertical drive shaft (601) coaxially arranged at the bottom with the horizontal main gear disk (504), a horizontal driven gear turntable (602) located at the top of the vertical drive shaft (601), a variable speed vertical gear set (603) in which any gear meshes vertically with the horizontal driven gear turntable (602), a top transverse drive shaft (604) for passing through the variable speed vertical gear set (603), a stainless steel frame (605) for supporting the top transverse drive shaft (604), a hub (606) passing through the top transverse drive shaft (604) via a tightening sleeve (607), a steel strand (608) wound around the hub (606), and a water-blocking baffle (609) located at the end of the steel strand (608) and capable of opening and closing the gate of the simulated sluice gate system (4).

8. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 1, is characterized in that... The pollutant monitoring system (7) includes a sampling port (701) located on the back of the simulated water tank (1), a sensor placement port (705) located on the back of the simulated water tank (1), a pollutant sensor (702) located in the sensor placement port (705), a pollutant data processor (703) connected to the pollutant sensor (702), and a display (705) connected to the pollutant data processor (703).

9. The experimental apparatus for simulating the migration and transformation of pollutants in coastal aquifers under the influence of sluice-controlled rivers flowing into the sea, as described in claim 1, is characterized in that... The camera system (8) includes a high-definition camera (801) located in front of the simulated water tank (1), a computer (802) connected to the high-definition camera (801), a light-blocking curtain (803) surrounding the camera and the simulated water tank, and a lighting fixture located directly above the simulated water tank.

10. An experimental method for an experimental apparatus simulating the migration and transformation of pollutants in a coastal aquifer under the influence of a sluice-controlled river flowing into the sea, characterized in that, Includes the following steps: S1. Sieve white quartz sand according to experimental requirements. The simulated seawater in the simulated seawater tank (509) is prepared by mixing deionized water and industrial salt in a mass ratio and stirring thoroughly until completely dissolved before use. S2. White quartz sand was filled into the simulated zone (111) of the sluice-controlled river-coastal aquifer using a saturated water method, ensuring that the water level was always higher than the sand surface during the filling process, and sand was filled in layers while water was being injected; according to the experimental design, a sluice-controlled river channel device (401) was installed inside the simulated zone (111) of the sluice-controlled river-coastal aquifer, and the channel body (4011) was fixed above the simulated water tank (1) by means of an angle adjustment bracket (4013), with the permeable holes (4015) at the bottom of the channel body (4011) facing downwards and in contact with the aquifer. Adjust the position of the impermeable regulating slide plate (4012) and control the length of the permeable area from 40cm to 100cm according to the experimental requirements; adjust the inclination angle of the channel body (4011), install the gate chamber assembly (402) at the downstream end of the channel body (4011), and seal the gate pier body (4021) and the end of the channel body (4011) with a flexible water-stop rubber sleeve (4016); fix the porous energy dissipation abutment plate (403) at the flange interface (4023) on the downstream side of the gate pier body (4021); S3. Deionized water is injected into the surface water storage tank (203) and the groundwater storage tank (207) respectively; standard pollutant solutions are prepared into the first standard solution tank (301), the second standard solution tank (302) and the third standard solution tank (303) respectively; the pollutant injection probe (307) is inserted into the simulated water tank (1), and the position of the probe tip is adjusted to near the upstream, midstream or downstream interface of the aquifer according to the experimental design; S4. Pour the prepared simulated seawater into the simulated seawater tank (509), start the first water pump (501), and adjust its flow rate to a constant value. The second water pump (502) is started, and the main controller (511) adjusts the target tidal level curve accordingly. The voltage signal of the control drive motor (507) is obtained and transmitted to the drive motor (507) through the transformer signal generator (508). The drive motor (507) rotates forward and reverse according to the voltage signal and drives the input vertical gear (505) to rotate, which in turn causes the horizontal main gear disk (504) to rotate. Through gear meshing, the opening of the flow regulating valve (503) changes, thereby changing the actual drainage flow of the second water pump (502). It is observed whether the water level in the nonlinear tidal signal generation area (112) shows periodic rise and fall to ensure that the water level change amplitude meets the design requirements. According to the experimental requirements, a suitable gear is selected in the variable speed vertical gear set (603) to rotate with the horizontal driven gear. The disc (602) is engaged, and different mechanical transmission ratios are set; one end of the steel strand (608) is fixed in the spiral groove of the hub (606), and the other end is connected to the top of the baffle plate (609). The length of the steel strand (608) is adjusted so that the lower edge of the baffle plate (609) is a certain distance from the bottom of the channel body (4011); the transformer signal generator (508) is started, the tidal waveform parameters are set, and the tidal water level change and the gate lifting action can be synchronized. It is verified that when the tide recedes, the flow regulating valve (503) opens, the baffle plate (609) rises, and the gate opens; when the tide rises, the flow regulating valve (503) closes, the baffle plate (609) falls, and the gate closes. S5. According to the experimental design, install pollutant sensors (702) in the sensor mounting holes (705) on the back of the simulated water tank (1); lead out the cable of the pollutant sensor (702) through the wiring hole on the back of the simulated water tank (1) and connect it to the pollutant data processor (703); connect the pollutant data processor (703) to the display (704), set the data acquisition frequency, and display the pollutant concentration change curves of each monitoring point in real time; set up a high-definition camera (801) on the front of the simulated water tank (1), adjust the focal length so that the entire gate-controlled river-coastal aquifer simulation area (111) is within the field of view; evenly arrange lighting panels directly above the simulated water tank (1); connect the high-definition camera (801) to the computer (802) through the data cable; build a light-blocking curtain (803) around the simulated water tank (1) to surround the high-definition camera (801), lighting fixtures and the simulated water tank (1) to create a darkroom environment; S6. Activate the terrestrial surface-subsurface runoff simulation system (2), inject the designed flow rate of surface runoff into the river channel (4011) through a high-flow-rate variable frequency pump (204), and inject the designed flow rate of subsurface runoff into the aquifer inlet (107) through a BW100 peristaltic pump (208) to simulate the terrestrial hydrological process; activate the nonlinear tidal simulation system (5), start the first pump (501) and the second pump (502), control the drive motor (507) to run through the transformer signal generator (508), generate the designed nonlinear tidal waveform, and the small-diameter flue inlet / outlet (108) and the large-diameter flue inlet / outlet (109) work simultaneously in the nonlinear tidal signal generation area. (112) Periodic water level fluctuations are formed within the water; after the river flow, groundwater runoff and tidal waveforms have been running stably for a period of time, the pollutant simulation system (3) is started. According to the experimental design, the first BW100 peristaltic pump (304), the second BW100 peristaltic pump (305) or the third BW100 peristaltic pump (306) are selected, and pollutant solutions with different color markings are injected into the aquifer or the designed location of the river through the pollutant injection probe (307); during the experiment, water samples at different depths and locations of the aquifer are collected periodically through the sampling hole (701) on the back of the simulated water tank (1) using a syringe, and the complete pollutant injection-migration-dilution-conversion process is recorded. The specific steps are as follows: S6.

1. Without starting the nonlinear tidal simulation system (5) and the tidal-gate linkage system (6), record the initial reference water level after the water level in the simulation tank (1) stabilizes. and background concentration at each monitoring point ,in The spatial coordinates of the pollutant sensor (702) in the simulated zone (111) of the sluice-controlled river-coastal aquifer. The horizontal distance from the landside boundary. , The vertical height from the bottom of the tank. ; S6.

2. Start the land-based surface-subsurface runoff simulation system (2) and record the input flux; inject the designed flow rate of surface runoff into the river channel (4011) through a high-flow-rate variable frequency pump (204) and record the surface runoff input flow rate. Groundwater at the designed flow rate is injected into the aquifer inlet (107) using a BW100 peristaltic pump (208), and the groundwater recharge flow rate is recorded. After the river flow, groundwater runoff, and aquifer water level have stabilized, proceed to the next step. S6.

3. Start the nonlinear tidal simulation system (5), record the tidal water level time series, start the first water pump (501) and the second water pump (502), control the drive motor (507) through the transformer signal generator (508) to generate a nonlinear tidal waveform; deploy a water level sensor (510) in the nonlinear tidal signal generation area (112) to record the real-time tidal water level time series. ; S6.

4. Start the tidal gate linkage system (6), record the gate status parameters, and record the gear transmission ratio set in the current experiment. Measure the displacement of the baffle plate (609) and record the gate opening time series in real time. And calculate the gate state function accordingly. : ， Simultaneously record the moment when the gate switches from closed to open during each tidal cycle. and the moment of switching from on to off Calculate the gate opening duration in a single cycle. ; S6.

5. Start the pollutant simulation system (3), record the injection parameters, and select to start the first BW100 peristaltic pump (304), the second BW100 peristaltic pump (305), or the third BW100 peristaltic pump (306) according to the experimental design. Insert the pollutant probe (307) into the simulation tank (1) at the designed position and record the pollutant injection flow rate. and injection concentration The injection location coordinates are ; S6.

6. Run the experiment continuously for a period of time, and collect the following parameter data synchronously: River water level: Time series of river water levels in a variable permeability channel (4011) ; Pollutant concentration field: Pollutant sensor (702) collects pollutant concentration data at each monitoring point. The pollutant data processor (703) and display (704) display the concentration-time curve in real time; the spatial average concentration of the sensors in the river channel is calculated respectively. Spatial average concentration of sensors within the aquifer ; Salinity distribution: The conductivity of each monitoring point was simultaneously collected using a pollutant sensor (702) and converted into salinity. Used to identify the location of the brackish water interface; Optical images of pollutant plumes: A high-resolution camera (801) takes frontal images of the simulated aquifer zone (111) at time intervals to obtain the spatial distribution grayscale field of the stained pollutants. Convert grayscale values ​​into a two-dimensional concentration field Pollutant concentration based on pollutant sensor (702) Concentration field obtained by correcting optical images ; During the experimental operation, the following key exchange fluxes were estimated online based on the collected water level data: River-aquifer infiltration exchange flow: Because the river water level is always higher than the aquifer groundwater level, river water continuously replenishes the aquifer through unidirectional downward infiltration of the riverbed medium. River-aquifer infiltration exchange flow... The value is always positive; according to Darcy's law, the vertical infiltration exchange flow from the river channel to the aquifer is: ， in, The riverbed permeability coefficient, The effective infiltration area between the riverbed and the aquifer. The thickness of the permeable layer in the riverbed. This refers to the elevation of the riverbed. The water level in the inner channel of the permeable channel body (4011) is changed; Gate discharge flow rate: calculated according to the gate hydraulic formula: ， in, For the clear width of the gate, The real-time tidal water level downstream of the sluice gate. It is the acceleration due to gravity; S7. After the experiment, all collected data were processed, and a quantitative analysis of the migration and transformation of pollutants in the coastal aquifer under the influence of the sluice gate-controlled river flowing into the sea was conducted. All pollutant sensor data were then standardized to the same time reference. For concentration time series Perform median filtering for noise reduction; A set of mass conservation equations for a coupled two-region system of sluice-controlled river channels and coastal aquifers was established. The sluice-controlled river-coastal aquifer system was divided into two coupled subsystems: the river channel region and the coastal aquifer region. Pollutant mass conservation equations were established for each subsystem. River channel mass conservation equation: ， Mass conservation equation for coastal aquifer regions: ， in The volume of water in the river channel; The volume of the aquifer; The average pollutant concentration in the river channel. This represents the average pollutant concentration in the aquifer. For surface input flow, Inputting pollutant concentrations onto the surface; For groundwater recharge flow, The concentration of pollutants in groundwater. This refers to the infiltration exchange flow between the river channel and the aquifer. The discharge flow rate of the gate; For the gate state function, This refers to the discharge flow from the aquifer to the sea. This refers to the seawater intrusion flow into the aquifer. The concentration of pollutants in seawater, Porosity To inject pollutants into the river flow, Injecting aquifer flow to pollutants, To determine the concentration of pollutants injected; The rate of change of pollutant mass in the river over time; The pollutant flux carried in by surface runoff, The flux of pollutants carried away by the aquifer is replenished by the infiltration of river water. The amount of pollutants discharged when the gate is opened. The flux of tracer pollutants injected into the river during the experiment; The rate of change of the mass of pollutants in the pore water of the aquifer over time. Porosity; The flux of pollutants carried by terrestrial groundwater replenishment. This refers to the flux of pollutants carried by river water as it infiltrates into the aquifer. This refers to the pollutant flux carried away by the aquifer as it discharges towards the sea. This refers to the flux of pollutants brought in by seawater intrusion into the aquifer. The flux of tracer pollutants injected into the aquifer during the experiment; pass The project achieves coupling between two subsystems: the river channel and the aquifer. The river channel is the source of pollutants, and the aquifer is the sink. The gate state function... The total amount of pollutants entering the aquifer is indirectly regulated by controlling the discharge flow rate.

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