An experimental device and method for simulating seawater intrusion in a coastal aquifer

Abstract

The application discloses an experimental device and method for simulating seawater intrusion in a coastal aquifer, which comprises a central water tank, a fresh water constant temperature water tank and a salt water constant temperature water tank, fresh water storages and salt water storages are arranged at two ends of the central water tank respectively, a fresh water inlet pipe and a fresh water outlet pipe are arranged between the fresh water constant temperature water tank and the fresh water storage, and a salt water inlet pipe and a salt water outlet pipe are arranged between the salt water constant temperature water tank and the salt water storage. The device has the characteristics of reasonable structure, low manufacturing cost, accurate monitoring and the like, and can easily realize similar simulation experiments of seawater intrusion in a coastal aquifer, has the advantages of less investment, flexible use, good experimental effect, repeated use, convenient recovery and the like, and can realize accurate simulation of seawater intrusion in a coastal aquifer through simple experimental method steps and low implementation cost.

Description

Technical Field

[0001] This invention belongs to the field of indoor physical similarity simulation experiments, and relates to seawater intrusion simulation experiments, specifically to an experimental device and method for simulating seawater intrusion in coastal aquifers. Background Technology

[0002] Water is an indispensable resource for humankind, and groundwater, as a crucial component of water resources, is one of the main sources of water supply for many cities and agricultural irrigation. With increasing human demand for water resources, the extraction of groundwater is also constantly increasing. However, there is insufficient understanding of groundwater resources, and a lack of scientific evaluation of groundwater distribution and reserves. Coastal aquifers are the main source of freshwater resources in coastal areas, and their management is of great significance to the socio-economic development of these regions. Seawater intrusion, a common natural disaster in coastal areas, has a significant impact on the development and utilization of groundwater resources in coastal aquifers.

[0003] In many coastal areas, excessive groundwater extraction has led to a significant drop in groundwater levels. The lowered groundwater level is unable to withstand the osmotic pressure of seawater, causing it to infiltrate the land through underground pores, fissures, or dissolution cavities. This seawater intrusion transforms freshwater areas into saline areas, resulting in soil salinization, abandonment of drinking water wells, and reduced crop yields. Due to the complexity of geological strata and the fluctuations in seawater levels, the scale and process of seawater intrusion are highly complex, and existing theoretical calculation models and testing methods are insufficient to accurately reflect the phenomenon. Therefore, developing an experimental device and method to simulate seawater intrusion in coastal aquifers is of great significance in helping to reveal the mechanisms, causes, and development processes of seawater intrusion.

[0004] Currently, indoor simulation methods are an important approach for simulating seawater intrusion and studying its mechanisms. However, traditional indoor experiments have several problems: ignoring the influence of temperature; difficulty in adjusting water levels during experiments; high cost of traditional simulation devices, which cannot be easily modified; and difficulty in accurately obtaining some data during experiments.

[0005] Therefore, a new technological solution is needed to address these issues. Summary of the Invention

[0006] Objective of the Invention: To overcome the shortcomings of existing technologies, this invention provides an experimental apparatus and method for simulating seawater intrusion in coastal aquifers. The apparatus features a reasonable structure, low manufacturing cost, and accurate monitoring, making it easy to conduct similar simulation experiments of seawater intrusion in coastal aquifers. The method is simple in procedure, low in implementation cost, and can achieve accurate simulation of seawater intrusion in coastal aquifers.

[0007] Technical solution: To achieve the above objectives, the present invention provides an experimental device for simulating seawater intrusion in coastal aquifers, comprising a central water tank, a freshwater constant-temperature tank, and a brine constant-temperature tank. Freshwater and brine tanks are respectively provided at both ends of the central water tank. A freshwater inlet pipe and a freshwater outlet pipe are provided between the freshwater constant-temperature tank and the freshwater tank. A brine inlet pipe and a brine outlet pipe are provided between the brine constant-temperature tank and the brine tank.

[0008] The freshwater tank and the brine tank are connected to both ends of the central water tank, respectively, and are used to supply freshwater and brine to the central water tank.

[0009] The central water tank is equipped with several temperature sensors, which are used to measure the temperature distribution in the aquifer within the central water tank.

[0010] Furthermore, a freshwater buffer tank is provided between the freshwater tank and the central water tank, and a brine buffer tank is provided between the brine tank and the central water tank.

[0011] Furthermore, the central water tank includes a water tank frame, two first acrylic plates respectively disposed at the left and right ends of the water tank frame, a second acrylic plate disposed at the bottom of the water tank frame, a third acrylic plate disposed at the front of the water tank frame, and a fourth acrylic plate disposed at the rear of the water tank frame.

[0012] The first acrylic plate has several evenly arranged water inlet holes; the second acrylic plate located at the bottom of the water tank frame has drainage holes; the third acrylic plate is double-layered and vacuum-sealed inside for easy heat insulation; the fourth acrylic plate has several evenly arranged prefabricated mounting holes, through which the temperature sensor is installed on the central water tank.

[0013] Furthermore, the freshwater constant temperature water tank is connected to the upper part of the freshwater tank via a freshwater inlet pipe, and the freshwater tank is connected to the lower part of the freshwater constant temperature water tank via a freshwater outlet pipe; the brine constant temperature water tank is connected to the upper part of the brine tank via a brine inlet pipe, and the brine tank is connected to the lower part of the brine constant temperature water tank via a brine outlet pipe.

[0014] Furthermore, the freshwater drain pipe is equipped with an overflow device at its end inside the freshwater tank; the brine drain pipe is also equipped with an overflow device at its end inside the brine tank.

[0015] Furthermore, both the freshwater inlet pipe and the brine inlet pipe are equipped with water pumps and flow meters.

[0016] Furthermore, both the freshwater drain pipe and the brine drain pipe are equipped with valves.

[0017] This invention also provides an experimental method for simulating seawater intrusion in coastal aquifers, comprising the following steps:

[0018] S1: Before the experiment, clean the freshwater tank, freshwater buffer tank, central water tank, brine buffer tank and brine tank, and fill the central water tank with quartz sand with certain gradation parameters.

[0019] S2: Prepare the required deionized water and inject it into the fresh water and salt water constant temperature tanks respectively. Add a certain amount of NaCl to the salt water constant temperature tank to make its salinity meet the experimental requirements. Add a staining agent to the salt water constant temperature tank to stain the salt water.

[0020] S3: Turn on the indoor air conditioner, turn on the heating switches for the freshwater constant temperature water tank and the brine constant temperature water tank, and set the heating temperature;

[0021] S4: After the room temperature and the water temperature in the freshwater and brine constant temperature water tanks reach the set value, pump the freshwater in the freshwater constant temperature water tank into the freshwater tank, and make the freshwater level in the freshwater tank slightly lower than the set brine side water level.

[0022] S5: Adjust the water pump flow rate of the freshwater tank side pump to the required flow rate, use the water pump to pump the brine in the brine constant temperature water tank into the brine tank, and open the brine drain pipe at the bottom of the brine tank so that the overflowing brine in the brine tank flows back into the brine constant temperature water tank.

[0023] S6: Turn on the temperature sensor system, activate all temperature sensors, and turn on the camera. The experiment officially begins.

[0024] S7: During the experiment, add high-concentration salt water to the constant temperature salt water tank to maintain the salinity of the salt water in the constant temperature salt water tank at the level required for the experiment.

[0025] S8: After the experiment, turn off the temperature sensor system, turn off the camera, turn off all water pumps, close the fresh water drain pipe and the brine drain pipe, open the drain pipe of the central water tank to drain all the water in the central water tank, brine buffer tank and fresh water buffer tank, take out the water-containing quartz sand in the central water tank, rinse it with fresh water and let it dry to prepare for the next experiment.

[0026] In this invention, the freshwater constant temperature water tank consists of a water tank and a heating device; the brine constant temperature water tank consists of a water tank and a heating device; the freshwater constant temperature water tank is supplied with water to the freshwater tank by a water pump through a water pipe, and the water supply flow rate can be controlled by a flow meter or the water level can be controlled by an overflow device; the brine constant temperature water tank is supplied with water to the brine tank by a water pump through a water pipe, and the water level is controlled by an overflow device.

[0027] Beneficial effects: Compared with existing technologies, this invention can accurately simulate the seawater intrusion process in coastal aquifers. Furthermore, compared with traditional simulation methods, it can consider the influence of different freshwater and seawater temperatures on seawater intrusion. The method of this invention can not only visually demonstrate seawater intrusion through staining, but also measure the temperature distribution in the aquifer using temperature sensors, thereby further deepening the research on seawater intrusion. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the device of the present invention;

[0029] Figure 2 This is a schematic diagram of the central water tank structure;

[0030] Figure 3 yes Figure 1 Floor plan;

[0031] Figure 4 yes Figure 1 The left view;

[0032] Figure 5 yes Figure 1 The right view;

[0033] Figure 6 yes Figure 1 Top view;

[0034] Figure 7 This is a schematic diagram showing the usage state of the experimental method of the present invention. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0036] like Figures 1-6 As shown, the present invention provides an experimental device for simulating seawater intrusion in a coastal aquifer, including a central water tank 3, a freshwater constant-temperature water tank 7, and a brine constant-temperature water tank 5. A freshwater tank 11 and a brine tank 10 are respectively installed at both ends of the central water tank 3. A freshwater buffer tank 6 is installed between the freshwater tank 11 and the central water tank 3, and a brine buffer tank 4 is installed between the brine tank 10 and the central water tank 3. There are no barriers between the freshwater buffer tank 6 and the freshwater tank 11, and no barriers between the brine buffer tank 4 and the brine tank 11. A freshwater inlet pipe 13 and a freshwater outlet pipe 9 are installed between the freshwater constant-temperature water tank 7 and the freshwater tank 11, and a brine inlet pipe 16 and a brine outlet pipe 17 are installed between the brine constant-temperature water tank 5 and the brine tank 10.

[0037] The central water tank 3 is located on the upper part of the bottom support frame 1. The overall structure of the central water tank 3 is a rectangular iron frame. The central water tank 3 includes a water tank frame 3.1, two first acrylic plates 3.3 respectively set at the left and right ends of the water tank frame 3.1, a second acrylic plate 3.2 set at the bottom of the water tank frame 3.1, a third acrylic plate 3.4 set at the front of the water tank frame 3.1, and a fourth acrylic plate 3.5 set at the rear of the water tank frame 3.1. The first acrylic plate 3.3 has several evenly arranged water inlet holes 3.8. The second acrylic plate 3.2 at the bottom of the water tank frame 3.1 has a drain hole 3.7, which is connected to the water tank drain pipe 2. The fourth acrylic plate 3.5 has several evenly arranged prefabricated installation holes 3.6.

[0038] Each prefabricated mounting hole 3.6 has a corresponding temperature sensor 8 installed. All the temperature sensors 8 form a temperature sensor system, which is used to measure the temperature distribution in the aquifer within the central water tank 3.

[0039] The freshwater constant temperature water tank 7 is connected to the upper part of the freshwater tank 11 via the freshwater inlet pipe 13, and the freshwater tank 11 is connected to the lower part of the freshwater constant temperature water tank 7 via the freshwater outlet pipe 9; the brine constant temperature water tank 5 is connected to the upper part of the brine tank 10 via the brine inlet pipe 16, and the brine tank 10 is connected to the lower part of the brine constant temperature water tank 5 via the brine outlet pipe 17; the end of the freshwater outlet pipe 9 located inside the freshwater tank 11 is equipped with an overflow device 12, and similarly, the end of the brine outlet pipe 17 located inside the brine tank 10 is also equipped with an overflow device 12; both the freshwater inlet pipe 13 and the brine inlet pipe 16 are equipped with a water pump 15 and a flow meter 14, and both the freshwater outlet pipe 9 and the brine outlet pipe 17 are equipped with valves;

[0040] In this embodiment, to improve the versatility of the system, the power and diameter of the water pump 15, fresh water inlet pipe 13, and brine inlet pipe 16 can be selected according to experimental requirements; in order to ensure good sealing performance of the central water tank 3, the contact position between the water tank frame 3.1 and the acrylic plate is filled with sealant.

[0041] The experimental apparatus for simulating seawater intrusion in coastal aquifers provided by this invention can simulate both constant and non-constant water head conditions as needed. The method for setting a constant water head involves adjusting the overflow device 12 to a predetermined position, adding freshwater / saltwater from the freshwater tank 11 / saltwater tank 10, ensuring the water flow covers the overflow device 12, and flows towards the freshwater buffer tank 6 / saltwater buffer tank 4. This ensures a continuous flow of freshwater / saltwater from the freshwater tank 11 / saltwater tank 10 into the freshwater buffer tank 6 / saltwater buffer tank 4, maintaining a constant water head. The method for setting a non-constant water head involves adjusting the height of the overflow device 12 during the experiment to simulate a non-constant water head.

[0042] Based on the above-mentioned seawater intrusion simulation experimental apparatus, the present invention also provides an experimental method for simulating seawater intrusion in coastal aquifers, comprising the following steps:

[0043] S1: Before the experiment, clean the freshwater tank 11, freshwater buffer tank 6, central water tank 3, brine buffer tank 4 and brine tank 10, and fill the central water tank 3 with quartz sand with certain gradation parameters.

[0044] S2: Prepare the required deionized water and inject it into the fresh water constant temperature tank 7 and the saline constant temperature tank 5 respectively. Add a certain amount of NaCl to the saline constant temperature tank 5 to make its salinity meet the experimental requirements. Add a staining agent to the saline constant temperature tank 5 to stain the saline.

[0045] S3: Turn on the indoor air conditioner, turn on the heating switches of the freshwater constant temperature water tank 7 and the brine constant temperature water tank 5, and set the heating temperature;

[0046] S4: Wait for the indoor temperature. After the water temperature in the freshwater constant temperature tank 7 and the brine constant temperature tank 5 reaches the set value, use the water pump 15 to pump the freshwater in the freshwater constant temperature tank 7 into the freshwater tank 11, and make the freshwater level in the freshwater tank 11 slightly lower than the set brine side water level.

[0047] S5: Adjust the water pump flow rate of the freshwater tank side pump to the required flow rate, use the water pump 15 to pump the brine in the brine constant temperature water tank 5 into the brine tank 10, and open the brine drain pipe 17 at the bottom of the brine tank 10 so that the brine overflowing in the brine tank 10 flows back into the brine constant temperature water tank 5.

[0048] S6: Turn on the temperature sensor system, activate all temperature sensors 8, and turn on the camera. The experiment officially begins.

[0049] S7: During the experiment, add high-concentration salt water to the constant temperature water tank 5 to maintain the salinity of the salt water in the constant temperature water tank 5 at the level required for the experiment.

[0050] S8: After the experiment, turn off the temperature sensor system, turn off the camera, turn off all water pumps, close the valves of fresh water drain pipe 9 and brine drain pipe 17, open the drain pipe 2 below the central water tank 3 to drain all the water in the central water tank 3, brine buffer tank 4 and fresh water buffer tank 6, take out the water-containing quartz sand in the central water tank 3, rinse it with fresh water and let it dry to prepare for the next experiment.

[0051] To verify the effectiveness of the above scheme, this embodiment applies the seawater intrusion simulation experimental device to a specific example, taking seawater intrusion in a coastal aquifer in a certain coastal area as an example. Figure 7 As shown, the specific experimental procedure is as follows:

[0052] Step 1: According to the experimental design requirements, a central water tank 3 with dimensions of 2.2m × 1.0m × 0.1m (length × height × width) is selected. The dimensions of the iron rectangular water tank frame 3.1 are slightly larger than those of the central water tank 3. Thermal insulation material is laid on the outside of the freshwater tank 11, freshwater buffer tank 6, central water tank 3, brine buffer tank 4, and brine tank 10. Before the experiment, the freshwater tank 11, freshwater buffer tank 6, central water tank 3, brine buffer tank 4, and brine tank 10 are cleaned. Quartz sand with certain gradation parameters is filled into the central water tank 3 to a height of 0.9m. It is compacted while being filled to make its compaction degree as close as possible to the actual geological conditions on site.

[0053] Step 2: Prepare the required deionized water and pour it into the fresh water constant temperature tank 7 and the brine constant temperature tank 5. Add a certain amount of NaCl to the brine constant temperature tank 5 to make its salinity reach 35ppt. Add red dye to the brine constant temperature tank 5 to stain the brine.

[0054] Step 3: Turn on the indoor air conditioner and set the temperature to 25℃. Turn on the heating switches of the freshwater constant temperature water tank 7 and the brine constant temperature water tank 5, and set the heating temperature of the freshwater constant temperature water tank 7 to 25℃ and the heating temperature of the brine constant temperature water tank 5 to 40℃.

[0055] Step 4: After the indoor temperature reaches 25℃ and the water temperature in the freshwater constant temperature tank 7 and the brine constant temperature tank 5 reaches the set value, pump the freshwater in the freshwater constant temperature tank 7 into the experimental freshwater chamber using the water pump 15, and make the freshwater level in the freshwater chamber 11 slightly lower than the set brine side water level.

[0056] Step 5: Adjust the water pump flow rate of the freshwater tank side pump to the required flow rate. Use pump 15 to pump the brine from the brine constant temperature water tank 5 into the brine tank 10. Open the brine drain pipe 17 at the bottom of the brine tank 10 to allow the overflowing brine to flow back into the brine constant temperature water tank 5. Adjust the overflow device 12 and the water pump flow rate of pump 15 to make the water level in the brine tank reach the predetermined height.

[0057] Step Six: Turn on the temperature sensor system and the camera; the experiment officially begins.

[0058] Step 7: During the experiment, add high-concentration salt water to the constant temperature water tank 5 and start the stirring device in the constant temperature water tank 5 to maintain the salinity of the salt water in the constant temperature water tank 5 at the required level for the experiment.

[0059] Step 8: After recording and organizing the experimental data, proceed with the final steps. Turn off the temperature sensor system, turn off the camera, turn off all water pumps, close the valves of the freshwater drain pipe 9 and the brine drain pipe 17, and open the drain pipe 2 below the central water tank 3 to drain all the water from the central water tank 3, the brine buffer tank 4, and the freshwater buffer tank 6. Remove the water-containing quartz sand from the central water tank 3, rinse it with fresh water, and let it dry in preparation for the next experiment.

Claims

1. An experimental apparatus for simulating seawater intrusion in a coastal aquifer, for implementing an experimental method for simulating seawater intrusion in a coastal aquifer, characterized by, The experimental device for simulating seawater intrusion in a coastal aquifer comprises a central water tank, a fresh water constant temperature water tank and a salt water constant temperature water tank, the two ends of the central water tank are respectively provided with a fresh water bin and a salt water bin, a fresh water inlet pipe and a fresh water outlet pipe are arranged between the fresh water constant temperature water tank and the fresh water bin, and a salt water inlet pipe and a salt water outlet pipe are arranged between the salt water constant temperature water tank and the salt water bin; The fresh water bin and the salt water bin are respectively communicated with the two ends of the central water tank and are respectively used for providing fresh water and salt water into the central water tank; A plurality of temperature sensors are arranged on the central water tank and are used for measuring the temperature distribution in the aquifer in the central water tank; A fresh water buffer bin is arranged between the fresh water bin and the central water tank, and a salt water buffer bin is arranged between the salt water bin and the central water tank; Water pumps and flow meters are arranged on the fresh water inlet pipe and the salt water inlet pipe; The experimental method for simulating seawater intrusion in a coastal aquifer comprises the following steps: S1: before the experiment, the fresh water bin, the fresh water buffer bin, the central water tank, the salt water buffer bin and the salt water bin are cleaned, and quartz sand is filled into the central water tank; S2: prepare the required deionized water, and inject it into the fresh water constant temperature water tank and the salt water constant temperature water tank respectively, add NaCl into the salt water constant temperature water tank to make the salinity meet the experimental requirements, and add a dye into the salt water constant temperature water tank to dye the salt water; S3: turn on the indoor air conditioner, turn on the heating switches of the fresh water constant temperature water tank and the salt water constant temperature water tank, and set the heating temperature; S4: wait for the indoor temperature, after the water temperature in the fresh water constant temperature water tank and the salt water constant temperature water tank reaches the set value, pump the fresh water in the fresh water constant temperature water tank into the fresh water bin by using the water pump, and make the water level of the fresh water in the fresh water bin lower than the set water level on the salt water side; S5: adjust the water pumping flow rate of the water pump on the fresh water bin side to the required flow rate, pump the salt water in the salt water constant temperature water tank into the salt water bin by using the water pump on the salt water bin side, and open the salt water outlet pipe at the lower part of the salt water bin to make the overflowed salt water in the salt water bin flow back into the salt water constant temperature water tank; S6: open the temperature sensor system, start all the temperature sensors, and open the camera, and the experiment starts formally; S7: during the experiment, add high-concentration salt water into the salt water constant temperature water tank to maintain the salinity of the salt water in the salt water constant temperature water tank at the required level; S8: after the experiment, close the temperature sensor system, close the camera, close all the water pumps, close the fresh water outlet pipe and the salt water outlet pipe, open the water tank outlet pipe at the lower part of the central water tank, and drain all the water in the central water tank, the salt water buffer bin and the fresh water buffer bin, take out the quartz sand containing water in the central water tank, wash it with fresh water and dry it, and prepare for the next experiment.

2. The experimental apparatus for simulating seawater intrusion in a coastal aquifer according to claim 1, wherein The central water tank comprises a water tank frame body, two first acrylic plates arranged at the left and right ends of the water tank frame body, a second acrylic plate arranged at the bottom of the water tank frame body, a third acrylic plate arranged at the front of the water tank frame body, and a fourth acrylic plate arranged at the rear of the water tank frame body. The first acrylic plate is provided with a plurality of water inlet holes arranged uniformly; the second acrylic plate at the bottom of the sink frame body is provided with a water outlet hole; the third acrylic plate is double-layered and internally vacuumized; the fourth acrylic plate is provided with a plurality of prefabricated mounting holes arranged uniformly, and the temperature sensor is mounted on the central sink through the prefabricated mounting holes.

3. The experimental apparatus for simulating seawater intrusion in a coastal aquifer according to claim 1, wherein The fresh water constant temperature water tank is connected with the upper part of the fresh water bin through a fresh water inlet pipe, and the fresh water bin is connected with the lower part of the fresh water constant temperature water tank through a fresh water outlet pipe; the salt water constant temperature water tank is connected with the upper part of the salt water bin through a salt water inlet pipe, and the salt water bin is connected with the lower part of the salt water constant temperature water tank through a salt water outlet pipe.

4. The experimental apparatus for simulating seawater intrusion in a coastal aquifer according to claim 3, wherein The end of the fresh water outlet pipe in the fresh water bin is provided with an overflow device; the end of the salt water outlet pipe in the salt water bin is provided with an overflow device.

5. The experimental apparatus for simulating seawater intrusion in a coastal aquifer according to claim 1, wherein Valves are arranged on the fresh water outlet pipe and the salt water outlet pipe.

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