CN106840975B - Device and method for monitoring undercurrent exchange flux - Google Patents

Abstract

The invention discloses a device for monitoring undercurrent exchange flux, which comprises a water tank, wherein two sand baffles which are parallel to each other are vertically arranged along the inner wall of the water tank, an area between the two sand baffles is a ground surface water tank, an upstream water tank and a downstream water tank are respectively arranged on two sides of the ground surface water tank, the bottom of the upstream water tank is sequentially communicated with a water pump and an outlet tee joint through pipelines, the outlet tee joint is respectively communicated with a pipeline heating device and a pipeline cooling device through pipelines, the pipeline heating device and the pipeline cooling device are jointly communicated with an inlet tee joint through pipelines, the inlet tee joint is communicated with the bottom of the downstream water tank through pipelines, the inlet tee joint is also connected with a water supply pipeline, and the water supply pipeline is communicated with a water supply tank. The transient process problem of the undercurrent exchange can be researched by controlling the surface water heating and cooling of the water tank. The invention also discloses a method for monitoring the undercurrent exchange flux.

Description

Device and method for monitoring subsurface exchange flux

technical field

The invention belongs to the technical field of hydraulic engineering test equipment, and relates to a device for monitoring subsurface exchange flux, and also relates to a method for monitoring subsurface exchange flux by using the device.

Background technique

The hyporheic zone is a water-saturated sediment layer in the river bed. It is an area where river water and groundwater interact. There is an exchange and transition of material and energy between the overlying water body and groundwater. It is an important part of the river ecosystem. As an excellent carrier of heat, water will carry information on energy changes during the flow of water. Observing the temporal and spatial distribution of the temperature field at the bottom of rivers, lakes, wetlands, and canals can determine the exchange process between groundwater and surface water.

At present, most of the methods for studying the process mode of subsurface flow exchange in the river bed are realized by laboratory experiments. According to domestic and foreign literature, in the past, the flume device was mostly used for solute tracing, surface water hydrodynamic changes, changes in river bed morphology and sediment permeability changes, etc., to study the subsurface exchange process model of the river bed. However, the anisotropy of the sediment and the heterogeneity of the solute distribution in the test process make it difficult to measure its concentration accurately and the error is large, and it cannot accurately simulate the transient process of the subsurface flow exchange between surface water and groundwater.

Contents of the invention

The purpose of the present invention is to provide a device for monitoring the flux of subsurface exchange, which solves the problem in the prior art that the heating and cooling of the surface water in the tank cannot be controlled to study the transient process of subsurface exchange.

Another object of the present invention is to provide a method of monitoring subsurface exchange flux.

The technical solution adopted in the present invention is a device for monitoring the exchange flux of subsurface flow, which includes a water tank, and two mutually parallel sand baffles are arranged vertically along the inner wall of the water tank, and the sand baffles divide the water tank into an upstream water tank and a surface water tank. , the downstream water tank, the area between the two sand baffles is the surface water tank, the interior of the surface water tank is divided into a water layer and a sediment layer from top to bottom, and the bottom of the upstream water tank is connected to a water pump through a pipeline, and the water pump is connected to a water tank through a pipeline. The outlet tee, the outlet tee is respectively connected with the pipeline heating device and the pipeline cooling device through the pipeline, the pipeline heating device and the pipeline cooling device are connected through the pipeline together with the inlet tee, the inlet tee is connected with the bottom of the downstream water tank through the pipeline, and the inlet tee It is also connected with a water supply pipeline, and the water supply pipeline is connected with a water supply tank. A temperature sensor array is arranged on the inner wall of the sediment layer, and the temperature sensor is connected to a temperature recorder through a wire. The circulation valve is provided with a water supply valve on the water supply pipeline.

The pipeline cooling device includes a cooling water tank, the outlet tee is connected to the cooling water tank through the pipeline, the cooling water tank is connected to the inlet tee through the pipeline, the cooling water tank is also connected to the cooling circulating water inlet pipe and the cooling circulating water return pipe, and the cooling circulating water inlet pipe is connected to There is a circulating water pump, the cooling circulating water pump is connected to the water supply tank, the cooling circulating water return pipe is connected to the cooling circulating water return pump, the cooling circulating water return pump is connected to the water supply tank, and the cooling circulating water return pipe is provided with a return valve , between the upstream water tank and the water-passing layer, there is an energy-dissipating orifice plate, and a plurality of holes are evenly opened on the energy-dissipating orifice plate, and the energy-dissipating orifice plate is fixed on the sand baffle, and a tailgate is arranged between the downstream water tank and the water-passing layer. The door device and the tailgate device are fixed on the sand baffle, and a water level regulating plate is arranged in the downstream water tank.

The pipeline between the upstream water tank and the water pump and the pipeline between the inlet tee and the downstream water tank are all set as plastic flexible hoses, the pipeline between the upstream water tank and the water pump is equipped with an electromagnetic flowmeter, and the outlet tee and the pipeline heating device A first valve is set on the pipeline between the outlet tee and the cooling water tank, a second valve is set on the pipeline between the outlet tee and the cooling water tank, a third valve is set on the pipeline between the pipeline heating device and the inlet tee, the cooling water tank and the inlet The pipeline between the tees is provided with a fourth valve.

The bottom of the downstream water tank is also connected with a return pipe, the other end of the return pipe is connected to the water supply tank, and the return pipe is provided with a normally closed valve.

The surface water tank is set as a cuboid. Two sand baffles are arranged sequentially along the length direction of the surface water tank. The temperature sensors are distributed at equal intervals at 5m in the middle of the length direction of the surface water tank. The temperature sensors are placed 10 and 20 meters below the sediment layer along the depth direction of the surface water tank , 30, and 50cm positions are arranged in sequence.

Both the upstream water tank and the downstream water tank are provided with temperature monitoring devices.

A hydraulic support rod and a rotatable support rod are arranged at the bottom of the water tank, a recorder placement board is fixedly installed on the outer wall of the water tank, and the temperature recorder is fixed on the recorder placement board.

The pipeline heating device includes a temperature controller and a temperature heating rod.

Another technical solution of the present invention is a method for monitoring subsurface exchange flux, which adopts a device for monitoring subsurface exchange flux, and is specifically implemented according to the following steps:

Step 1, add sediment to the surface water tank, then close the self-circulation valve, open the water supply valve, turn on the water pump, and supply water to the water tank from the water supply tank until the surface water level in the surface water tank is constant;

Step 2, close the water supply valve, open the self-circulation valve, change the opening of the water pump until the flow rate meets the experimental requirements, and stabilize the surface water level;

Step 3, adjust the surface water temperature, and save the temperature data and time data recorded by the temperature recorder during the water temperature change process;

Step 3.1, turn on the pipeline heating device to heat the surface water to the highest temperature required by the test, and turn off the pipeline heating device after the surface water is heated to the highest temperature required by the test;

Step 3.2, open the pipeline cooling device, cool down the surface water to the minimum temperature required by the experiment, and close the pipeline cooling device after the surface water is cooled to the minimum temperature required by the experiment;

Step 3.3, save the temperature data and time data recorded by the temperature recorder during the water temperature change process.

Step 4. Calculate the subsurface exchange volume of the surface water tank according to the temperature data and time data recorded by the temperature recorder. The formula for calculating the subsurface exchange volume per unit area is:

Where: κ _e is the effective thermal diffusivity m ² /s, C is the specific heat capacity of sediment J/m ³ /℃, C _w is the specific heat capacity of water J/m ³ /℃, Ar is the temperature of two temperature sensors at different depths amplitude ratio,

P为温度变化的周期，Δz为不同深度的两个测量点之间的直线距离。v is the infiltration rate of the river bed;

P is the period of temperature change, and Δz is the linear distance between two measurement points at different depths.

The present invention is also characterized in that,

Step 1 is specifically implemented according to the following steps:

Step 1.1, add sediment to the surface water tank, close the self-circulation valve, open the water supply valve, turn on the water pump, open the first valve, open the third valve, add clear water to the sediment layer of the water tank from the water supply tank to make the sediment layer Saturation is reached, that is, the water level just submerges the surface of the sediment layer, and the water level does not drop within hours;

Step 1.2, adjust the angle of the water level regulating plate so that the water depth of the water layer reaches the water level required by the experiment;

Step 3.1 is specifically implemented according to the following steps:

Step 3.1.1, turn on the pipeline heating device, set the maximum temperature required for the test on the temperature controller, and heat at a constant temperature;

Step 3.1.2, observe the temperature monitoring device, after the surface water is heated to the highest temperature required by the test, turn off the pipeline heating device, close the first valve, and close the third valve;

Step 3.2 is specifically implemented according to the following steps:

Step 3.2 is specifically implemented according to the following steps:

Step 3.2.1, open the second valve and the fourth valve to allow water to flow into the cooling water tank;

Step 3.2.1, after the cooling water tank is full, turn on the cooling circulating water pump and open the cooling circulating water outlet valve;

Step 3.2.2, turn on the cooling circulating water return pump;

Step 3.2.3, observe the temperature monitoring device, when the temperature drops to the minimum temperature required by the test, turn off the cooling cycle to pump water;

Step 3.2.4, when the water in the cooling water tank is exhausted, turn off the cooling circulation return water pump, at this time, it is a cycle.

The beneficial effects of the present invention are: a device for monitoring the exchange flux of the subsurface flow of the present invention can simulate the self-circulation of the subsurface flow exchange between the surface water and the underground water by setting the self-circulating water system between the upstream and downstream water tanks, and in the case of accurate temperature control The coupling test of surface water and groundwater is completed; the temperature at different positions is measured by the temperature sensor arranged inside the side wall of the surface water tank, so that the influence of groundwater on subsurface flow exchange can be studied by using the temperature tracer method. Through the qualitative analysis method of the temperature time series curve, the pore water temperature at the designated location is indirectly measured, and then the subsurface exchange flux is obtained.

Description of drawings

Fig. 1 is a structural representation of a device for monitoring subsurface exchange flux of the present invention;

Fig. 2 is the top view of Fig. 1;

Fig. 3 is the bottom view of Fig. 1;

Fig. 4 is a schematic diagram of the connection relationship between a temperature sensor and a temperature recorder of a device for monitoring subsurface exchange flux of the present invention;

Fig. 5 is a structural schematic diagram of a pipeline cooling device of a device for monitoring subsurface exchange flux of the present invention;

Fig. 6 is a schematic diagram of the installation relationship between the energy dissipation orifice and the sand retaining plate of a device for monitoring subsurface exchange flux of the present invention;

Fig. 7 is a partial pipeline connection schematic diagram of a device for monitoring subsurface exchange flux of the present invention;

Fig. 8 is a structural schematic diagram of a pipeline heating device of a device for monitoring subsurface exchange flux according to the present invention.

In the figure, 1. Water tank, 2. Water-passing layer, 3. Sediment layer, 4. Upstream water tank, 5. Downstream water tank, 6. Energy dissipation orifice, 7. Tailgate device, 8. Water level regulating plate, 9. First valve, 10. Temperature monitoring device, 11. Second valve, 12. Electromagnetic flowmeter, 13. Water pump, 14. Outlet tee, 15. Pipeline heating device, 16. Pipeline cooling device, 17. Inlet tee, 18. Self-circulation valve, 19. Cooling circulating water inlet pipe, 20. Cooling circulating water return pipe, 21. Cooling circulating water pump, 22. Return water valve, 23. Cooling circulating water return pump, 24. Water supply tank, 25 .Water supply pipe, 26. Water supply valve, 27. Temperature sensor, 28. Hydraulic support rod, 29. Rotatable support rod, 30. Return water pipe, 31. Temperature controller, 32. Temperature heating rod, 33. Temperature recorder, 34. Sand retaining plate, 35. Recorder placement plate, 36. Surface water tank, 37. The third valve, 38. The fourth valve, 39. Cooling water tank.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

A device for monitoring undercurrent exchange flux according to the present invention, as shown in Fig. 1-Fig. 1 is divided into upstream water tank 4, surface water tank 36, and downstream water tank 5. The area between the two sand retaining plates 34 is the surface water tank 36. The interior of the surface water tank 36 is divided into the water-passing layer 2 and the sediment layer from top to bottom. 3. The bottom of the upstream water tank 4 is connected with a water pump 13 through a pipeline, and the water pump 13 is connected with an outlet tee 14 through a pipeline, and the outlet tee 14 is respectively connected with a pipeline heating device 15 and a pipeline cooling device 16 through a pipeline, and the pipeline heating device 15 and pipeline cooling The device 16 is connected with the inlet tee 17 through the pipeline, the inlet tee 17 is connected with the bottom of the downstream water tank 5 through the pipeline, the inlet tee 17 is also connected with the water supply pipeline 25, and the water supply pipeline 25 is connected with the water supply tank 24, which is located in the sediment layer 3 The inner wall of the inner wall is provided with a temperature sensor 27 array, as shown in Figure 4, the temperature sensor 27 is connected with a temperature recorder 33 by a wire, and the pipeline between the inlet tee 17 and the downstream water tank 5 is provided with a self-circulation valve 18, and the water supply pipeline 25 is provided with water supply valve 26.

As shown in Figure 5, the pipeline cooling device 16 includes a cooling water tank 39, the outlet tee 14 is connected to the cooling water tank 39 through the pipeline, the cooling water tank 39 is connected to the inlet tee 17 through the pipeline, and the cooling water tank 39 is also connected to the cooling water inlet pipe 19 and the cooling circulating water return pipe 20, the cooling circulating water inlet pipe 19 is connected with a circulating water pump 21, the cooling circulating water pump 21 is connected to the water supply tank 24, and the cooling circulating water return pipe 20 is connected with a cooling circulating water return pump 23, The cooling circulating water return pump 23 is connected to the water supply tank 24, the cooling circulating water return pipe 20 is provided with a return valve 22, as shown in Figure 6, an energy dissipation orifice 6 is provided between the upstream water tank 4 and the water passing layer 2, A plurality of holes are evenly opened on the energy dissipation orifice plate 6, and the energy dissipation orifice plate 6 is fixed on the sand retaining plate 34, and a tailgate device 7 is arranged between the downstream water tank 5 and the water passing layer 2, and the tailgate device 7 is fixed on the barrier On the sand board 34 , a water level regulating plate 8 is arranged in the downstream water tank 5 .

As shown in Figure 7, the pipeline between the upstream water tank 4 and the water pump 13 and the pipeline between the inlet tee 17 and the downstream water tank 5 are all set as plastic flexible hoses, and the pipeline between the upstream water tank 4 and the water pump 13 is provided with The electromagnetic flowmeter 12, the pipeline between the outlet tee 14 and the pipeline heating device 15 is provided with a first valve 9, and the pipeline between the outlet tee 14 and the cooling water tank 39 is provided with a second valve 11, and the pipeline heating device 15 and the inlet tee 17 are provided with a third valve 37 , and the pipeline between the cooling water tank 39 and the inlet tee 17 is provided with a fourth valve 38 .

The bottom of the downstream water tank 5 is also connected with a return pipe 30 , the other end of the return pipe 30 is connected to the water supply tank 24 , and the return pipe 30 is provided with a normally closed valve.

The surface water tank 36 is arranged as a cuboid, and two sand baffles 34 are arranged successively along the length direction of the surface water tank 36. The temperature sensors 27 are distributed at equal intervals at 5 m in the middle of the length direction of the surface water tank 36. The temperature sensors 27 are located along the surface water tank 36 depth direction. The positions 10, 20, 30, and 50 cm below the sediment layer 3 are arranged in sequence.

Both the upstream water tank 4 and the downstream water tank 5 are provided with a temperature monitoring device 10 .

The bottom of the water tank 1 is provided with a hydraulic support rod 28 and a rotatable support rod 29 , a recorder placement plate 35 is fixedly installed on the outer wall of the water tank 1 , and a temperature recorder 31 is fixed on the recorder placement plate 35 .

As shown in FIG. 8 , the pipe heating device 15 includes a temperature controller 31 and a temperature heating rod 32 .

The working principle of a device for monitoring subsurface exchange flux of the present invention is as follows: when working, add sediment to the surface water tank 36, then close the self-circulation valve 18, open the water supply valve 26, open the water pump 13, open the first valve 9, The third valve 37 adds clear water to the sediment layer 3, so that the sediment layer reaches a saturated state, that is, the water surface just submerges the surface of the sediment layer 3, and the water level does not drop in 1 hour, and the angle of the water level regulating plate 8 is adjusted to make the The water depth of water layer 2 reaches the water level required by the experiment; then, close the water supply valve 25, open the self-circulation valve 18, change the opening degree of the water pump 13 and wait for the flow to reach the experimental requirement, so that the surface water level is stable; After the highest temperature required by the test is set on the device 31, adjust the second valve 11 and the fourth valve 38 to allow water to flow into the cooling water tank 39. At the same time, turn on the cooling circulation pump 21. When the water in the pipeline cooling water tank 39 is full, turn on the cooling water circulation. The water outlet valve 22 and the cooling circulating water return pump 23 are opened. By observing the temperature monitoring device 10, when the temperature drops to the minimum temperature required by the test, the cooling circulating water pumping 21 is closed. When the water in the cooling water tank 39 is pumped out, the cooling circulating returning water pump is closed. 23; Then observe and record the temperature data and time data recorded by the temperature recorder, and calculate the subsurface exchange volume of the surface water tank according to the temperature data and time data recorded by the temperature recorder. The temperature of the surface water in the surface water tank 36 is periodically changed by the pipeline heating device 15 and the pipeline cooling device 16, and the temperature of the pore water at the designated position is measured by the array of temperature sensors 27 arranged on the inner wall of the surface water tank 36, and then according to the temperature sequence Curve qualitative analysis method, the subsurface exchange flux between surface water and groundwater is studied by the temperature curve phase and amplitude changes of temperature sensors at different depths.

A kind of device of monitoring undercurrent exchange flux of the present invention is by setting pipeline heating device 15 and pipeline cooling device 16, and pipeline heating device 15 and cooling device 16 are connected in parallel, and temperature controller 31 is set on pipeline heating device 15, and cooling device 16 is connected with the cooling circulating water inlet pipe 19 and the cooling circulating water return pipe 20, the cooling circulating water inlet pipe 19 is connected with a circulating water pump 21, and the circulating water pump 21 is connected to the water supply tank 24, and the cooling circulating water return pipe 20 is connected with The circulating water return pump 23, the circulating water return pump 23 is connected to the water supply tank 24, and the cooling circulating water return pipe 20 is provided with a return valve 22, which can solve the problem of circulating water heating and cooling. When heating: adjust each matching valve so that The water passes through the pipeline heating device 15, and the water passes through the pipeline heating device installed on the pipeline, and the temperature required by the test is set by the temperature controller, so as to achieve the purpose of heating; when cooling: adjust the outlet tee of each valve to make the circulating water pass through the pipeline Cooling device 16, open the cooling circulating water pump 21 after this, pump water in the pipeline cooling device 16, wait to be filled with water in the pipeline cooling device, open the return water valve 22, open the cooling circulating water return water pump 20 simultaneously, pass through and pipeline cooling device The pipes in it form heat transfer, so that the temperature of the circulating water can be reduced, and then the temperature monitoring device installed in the upstream and downstream water tanks can choose the time to close the cooling device. The tailgate device 7 of the present invention is a sailing door blade, which is fixed on the sand retaining plate, and the water depth of the water layer 2 can be adjusted by adjusting the angle of the water level regulating plate 8; the diameter of the temperature heating device 15 of the present invention is 0.5m, and the length is 1.5m. m, the diameter of the pipeline cooling device is 0.5m, the length is 1.5m, the diameter of the cooling circulating water inlet pipe 19 and the cooling circulating water return pipe 20 is 0.1m; the temperature sensor 27 is TMC50-HD type, and the temperature recorder 33 adopts 4-channel UX120- 006 type, a temperature recorder 33 is connected with 4 temperature sensors 27, the range of the electromagnetic flowmeter 12 is 0-60L/s to monitor the flow of the surface water circulation system, the water pump 13 provides power for the surface water circulation; the water supply tank 24 provides the power for the entire system Provide water; at the end of the test, or when the water level in the surface water tank was too high during the experiment, the normally closed valve provided on the return pipe 30 could be opened to return the water in the water tank 1 to the water supply tank through the return pipe 30, thereby forming the whole Circulation of the system; the length, width and height of the surface water tank 36 can be 7m, 0.4m and 1.2m respectively, and the height of the surface water tank 36 is set to 1.2m mainly to consider to meet the subsurface exchange and not bump into the surface water tank 36 The lower boundary, and the setting of the width is to eliminate the problem of backflow of the side wall caused by the too narrow surface water tank; the connection between the upstream water tank 4 and the downstream water tank 5 and the surface water tank are all waterproof connections; the energy dissipation orifice 6 is a plexiglass plate with a thickness of 50mm , 192 holes with a diameter of 20mm are evenly drilled, and the energy dissipation orifice plate 6 can dissipate energy and guide the water flow into the surface water tank stably; the thickness of the sediment layer 3 is set to 70cm; The cooling circulating water pipe adopts a stainless steel pipe with a diameter of 100mm, and the water supply pipeline 25 adopts a stainless steel pipe with a diameter of 150mm; the water supply tank adopts a plastic box with a length, width and height of 2m, 1.4m and 1.2m; The pipeline between the inlet tee 17 and the downstream water tank 5 is a plastic telescopic hose mainly to consider the force on the pipeline after the slope is changed, and the use of the telescopic pipeline can effectively solve the problem of slope change; the hydraulic support rod 28 and the rotatable support rod 29. The angle of the water tank can be fine-tuned to simulate a certain slope situation. The temperature monitoring device 10 is a temperature measuring instrument, which can directly observe and measure the temperature of the water in the upstream and downstream water tanks.

In a device for monitoring subsurface exchange flux in the present invention, the energy dissipation orifice 6 can dissipate energy and guide the water flow in the upstream water tank 4 to stably enter the surface water tank 36, and the tailgate device 7 can control the flow from the surface water tank 36 into the downstream water tank 5 and fine-tune the flow rate, the water level regulating plate 8 can control the water level in the surface water tank 36 by adjusting its angle, the pipeline between the upstream water tank 4 and the water pump 13 and the pipeline between the inlet tee 17 and the downstream water tank 5 are made of plastic The setting of the telescopic hose can effectively adapt to the impact of the force on the pipeline due to the slope change. The temperature of the surface water in the surface water tank 36 is monitored by the temperature monitoring device 10. The electromagnetic flowmeter 12 is used to monitor the flow of the pipeline. The water pump 13 provides power for the surface water circulation, the pipeline heating device 15 heats the circulating water, the pipeline cooling device 16 cools the circulating water, the self-circulation valve 18 is used to control the opening and closing of the water in the circulating pipeline, and the cooling circulating water inlet pipe 19 is used to The water in the water supply tank is delivered to the pipeline cooling device, the cooling circulating water pump 21 pumps the water in the water supply tank to the pipeline cooling device, the return water valve 22 is used to control the water in the pipeline cooling device to enter the water supply tank, and the cooling cycle The water return pump 23 is used to pump the water in the pipeline cooling device to the water supply tank, the water supply tank 24 provides water for the whole system, the temperature sensor 24 is used to measure the pore water temperature at the designated position, the hydraulic support rod 28 and the rotatable support rod 29 plays the role of changing the slope, and at the same time as the support structure of the water tank, the return pipe 30 is used to recycle the water in the water tank to the water supply tank after the test is over, and the temperature controller 31 is used to control the temperature of the temperature heating rod in the pipeline heater, the temperature The heating rod 32 can transfer the heat generated by the alternating current to the circulating water in the pipe heater, the temperature recorder 33 is used to record the temperature measured by the temperature sensor, and the sand baffle 34 is used to block the sediment and prevent the sediment from entering the upper In the downstream water tank, the recorder placement plate 35 is used for fixedly placing the temperature recorder 27 .

A method for monitoring subsurface exchange flux of the present invention adopts a device for monitoring subsurface exchange flux, and is specifically implemented according to the following steps:

Step 1, add sediment in the surface water tank 36, then close the self-circulation valve 18, open the water supply valve 26, open the water pump 13, supply water to the surface water level in the surface water tank 36 by the water supply tank 24 to the water tank 1 constant;

Step 2, close the water supply valve 26, open the self-circulation valve 18, change the opening of the water pump 13 until the flow rate reaches the experimental requirements, and stabilize the surface water level;

Step 3, adjust the surface water temperature, and save the temperature data and time data recorded by the temperature recorder during the water temperature change process;

Step 3.1, turn on the pipeline heating device 15 to heat the surface water to the highest temperature required by the test, and turn off the pipeline heating device 15 after the surface water is heated to the highest temperature required by the test;

Step 3.2, open the pipeline cooling device 16, cool the surface water to the minimum temperature required by the experiment, and close the pipeline cooling device 16 after the surface water is cooled to the minimum temperature required by the experiment;

Step 3.3, save the temperature data and time data recorded by the temperature recorder 33 during the water temperature change process.

Step 4. Calculate the subsurface exchange volume of the surface water tank according to the temperature data and time data recorded by the temperature recorder. The formula for calculating the subsurface exchange volume per unit area is:

Where: κ _e is the effective thermal diffusivity m ² /s, C is the specific heat capacity of sediment J/m ³ /℃, C _w is the specific heat capacity of water J/m ³ /℃, Ar is the temperature of two temperature sensors at different depths amplitude ratio,

P为温度变化的周期，Δz为不同深度的两个测量点之间的直线距离。v is the infiltration rate of the river bed;

P is the period of temperature change, and Δz is the linear distance between two measurement points at different depths.

Step 1 is specifically implemented according to the following steps:

Step 1.1, add sediment in surface water tank 36, close self-circulation valve 18, open water supply valve 26, open water pump 13, open first valve 9, open the 3rd valve 37, by water supply tank 24 to the sediment layer of tank 1 Add clear water to 3 to make the sediment layer reach a saturated state, that is, the water surface just submerges the surface of the sediment layer 3, and the water level does not drop within 1 hour;

Step 1.2, adjust the angle of the water level regulating plate 8 so that the water depth of the water-passing layer 2 reaches the water level required by the experiment;

Step 3.1 is specifically implemented according to the following steps:

Step 3.1.1, turn on the pipeline heating device 15, and set the maximum temperature required for the test on the temperature controller 31, and heat at a constant temperature;

Step 3.1.2, observe the temperature monitoring device 10, after the surface water is heated to the highest temperature required by the test, turn off the pipeline heating device 15, close the first valve 9, and close the third valve 37;

Step 3.2 is specifically implemented according to the following steps:

Step 3.2 is specifically implemented according to the following steps:

Step 3.2.1, open the second valve 11 and the fourth valve 38 to allow water to flow into the cooling water tank 39;

Step 3.2.1, after the cooling water tank 39 is full, turn on the cooling circulating water pump 21, and open the cooling circulating water outlet valve 22;

Step 3.2.2, turn on the cooling circulating water return pump 23;

Step 3.2.3, observe the temperature monitoring device 10, when the temperature drops to the minimum temperature required by the test, turn off the cooling cycle pumping water 21;

Step 3.2.4, when the water in the cooling water tank 39 is pumped out, the cooling cycle return water pump 23 is turned off, and at this time, it is a cycle.

The temperature change period P of the present invention is obtained by analyzing the temperature measured by a sensor and drawing a corresponding temperature change curve.

When the present invention determines the effective thermal diffusivity κ _e , for the data measured by the same group of temperature sensors, the water velocity represented by the amplitude and the phase should be consistent, and the equation of the river bed infiltration rate about the amplitude is:

The equation of riverbed infiltration rate with respect to phase is:

That is: v _Ar = v _ΔΦ , then the effective thermal diffusivity κ _e is obtained;

in,

When the present invention determines the infiltration rate v of the river bed, for the data measured by the same group of temperature sensors, the water flow velocity represented by the amplitude and phase should be consistent, that is: v _Ar =v _ΔΦ , at this time, v _Ar =v _ΔΦ = v is the infiltration rate of the riverbed.

Example

Assuming that the room temperature is 16°C, that is, the initial temperature of the water is 16°C, the experiment requires heating to 26°C and cooling to 16°C;

Step 1, add sediment to the surface water tank 36, then close the self-circulation valve 18, open the water supply valve 26, turn on the water pump 13, and supply water to the water tank 1 by the water supply tank 24 until the surface water level in the surface water tank 36 is constant, specifically according to The following steps are implemented:

Step 1.1, add sediment in surface water tank 36, close self-circulation valve 18, open water supply valve 26, open water pump 13, open first valve 9, open the 3rd valve 37, by water supply tank 24 to the sediment layer of tank 1 Add clear water to 3 to make the sediment layer reach a saturated state, that is, the water surface just submerges the surface of the sediment layer 3, and the water level does not drop within 1 hour;

Step 1.2, adjust the angle of the water level regulating plate 8 so that the water depth of the water-passing layer 2 reaches the water level required by the experiment;

Step 2, close the water supply valve 26, open the self-circulation valve 18, change the opening of the water pump 13 until the flow rate reaches the experimental requirements, and stabilize the surface water level;

Step 3, adjust the surface water temperature, and save the temperature data and time data recorded by the temperature recorder during the water temperature change process;

Step 3.1: Turn on the pipeline heating device 15 to heat the surface water to the highest temperature required for the test. After the surface water is heated to 26°C, turn off the pipeline heating device 15. Specifically, follow the steps below:

Step 3.1.1, turn on the pipeline heating device 15, and set a constant temperature of 26°C on the temperature controller 31 for constant temperature heating;

Step 3.1.2, observe the temperature monitoring device 10, after the surface water is heated to 26°C, turn off the pipeline heating device 15, close the first valve 9, and close the third valve 37;

Step 3.2, turn on the pipeline cooling device 16, and close the pipeline cooling device 16 after the surface water cools down to 16°C, specifically follow the steps below:

Step 3.2.1, open the second valve 11 and the fourth valve 38 to allow water to flow into the cooling water tank 39;

Step 3.2.1, after the cooling water tank is full, turn on the cooling circulation pump 21, and when the water in the pipeline cooling device 16 is full, open the cooling circulation water outlet valve 22;

Step 3.2.2, turn on the cooling circulating water return pump 23;

Step 3.2.3, observe the temperature monitoring device 10, when the temperature drops to 16°C, turn off the cooling cycle pumping water 21;

Step 3.2.4, when the water in the cooling water tank 39 is pumped out, the cooling cycle return water pump 23 is turned off, and at this time, it is a cycle.

Step 3.3, save the temperature data and time data recorded by the temperature recorder 33 during the water temperature change process.

Step 4. Calculate the subsurface exchange volume of the surface water tank according to the temperature data and time data recorded by the temperature recorder. The formula for calculating the subsurface exchange volume per unit area is:

Where: κ _e is the effective thermal diffusivity m ² /s, C is the specific heat capacity of sediment J/m ³ /℃, C _w is the specific heat capacity of water J/m ³ /℃, Ar is the temperature of two temperature sensors at different depths amplitude ratio,

P为温度变化的周期，Δz为不同深度的两个测量点之间的直线距离。v is the infiltration rate of the river bed;

P is the period of temperature change, and Δz is the linear distance between two measurement points at different depths.

Claims (2)

1. A method for monitoring subsurface exchange flux, is characterized in that, specifically implements according to the following steps: Step 1, add sediment in the surface water tank (36), then close the self-circulation valve (18), open the water supply valve (26), turn on the water pump (13), and supply water to the tank (1) by the water supply tank (24) to The surface water level in the surface water tank (36) is constant; Step 2, close the water supply valve (26), open the self-circulation valve (18), change the opening of the water pump (13) until the flow rate meets the experimental requirements, so that the surface water level is stable; Step 3, adjust the surface water temperature, and save the temperature data and time data recorded by the temperature recorder (33) during the water temperature change process; Step 3.1, turn on the pipeline heating device (15) to heat the surface water to the highest temperature required by the test, and turn off the pipeline heating device (15) after the surface water is heated to the highest temperature required by the test; Step 3.2, open the pipeline cooling device (16), cool the surface water to the minimum temperature required by the experiment, and close the pipeline cooling device (16) after the surface water is cooled to the minimum temperature required by the experiment; Step 3.3, save the temperature data and time data of the temperature recorder record (33) in the water temperature change process; Step 4. Calculate the subsurface exchange volume of the surface water tank according to the temperature data and time data recorded by the temperature recorder. The formula for calculating the subsurface exchange volume per unit area is:

Where: κ _e is the effective thermal diffusivity (m ² /s), C is the specific heat capacity of sediment (J/m ³ /℃), C _w is the specific heat capacity of water (J/m ³ /℃), Ar is the different depth The temperature amplitude ratio of the 2 temperature sensors,

v is the infiltration rate of the river bed;

P is the period of temperature change, and Δz is the linear distance between two measurement points at different depths. 2. A kind of method for monitoring subsurface exchange flux according to claim 1, is characterized in that, step 1 is specifically implemented according to the following steps: Step 1.1, add sediment to the surface water tank (36), close the self-circulation valve (18), open the water supply valve (26), open the water pump (13), open the first valve (9), open the third valve (37) , add clear water to the sediment layer (3) of the water tank (1) from the water supply tank (24), so that the sediment layer reaches a saturated state, that is, the water surface just submerges the surface of the sediment layer (3), and the water level does not drop within 1 hour ; Step 1.2, adjust the angle of the water level regulating plate (8) to make the water depth of the water-passing layer (2) reach the water level required by the experiment; Step 3.1 is specifically implemented according to the following steps: Step 3.1.1, turn on the pipeline heating device (15), and set the maximum temperature required for the test on the temperature controller (31), and heat at a constant temperature; Step 3.1.2, observe the temperature monitoring device (10), after the surface water is heated to the highest temperature required by the test, turn off the pipeline heating device (15), close the first valve (9), and close the third valve (37); Step 3.2 is specifically implemented according to the following steps: Step 3.2.1, open the second valve (11) and the fourth valve (38), so that water flows into the cooling water tank (39); Step 3.2.1, after the cooling water tank (39) is full, turn on the cooling circulation pump (21), and open the cooling circulation water outlet valve (22); Step 3.2.2, turn on the cooling circulating water return pump (23); Step 3.2.3, observe the temperature monitoring device (10), when the temperature drops to the minimum temperature required by the test, turn off the cooling cycle pumping water (21); Step 3.2.4, when the water in the cooling water tank (39) is pumped out, the cooling cycle return pump (23) is closed, and at this time, it is a cycle.

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