Marine near-surface underground water level monitoring system

Abstract

The invention provides an ocean near-ground underground water level monitoring system which comprises a glass tube, a photovoltaic panel, a storage battery, a saline water power generation set, an inner tube, a spiral tube, a socket, a dustproof sponge, a sand prevention sponge, a modulation circuit and a chip. The chip is a single-chip microcomputer chip or a micro-control chip with data processing capability and operational capability, various program modules required by the device for processing data are pre-burnt in the chip, and the program modules comprise an initialization program of a counter / a setter, a measurement program of the output frequency of the oscillating circuit and a conversion program of converting the oscillation frequency to the water level position. An interlayer is formed between the outer tube and the inner tube, the interlayer of the glass tube is vacuumized, the inner tube is wound into a spiral tube by an enameled wire, saline water and the spiral tube form a variable inductor, water and salt have diamagnetism, the change of the surface of the saline water can cause the change of the inductance value of the variable inductor, and the spiral tube is packaged by the vacuum glass tube so as to prevent salt corrosion and biological attachment.

Description

Technical Field

[0001] The present invention relates to a groundwater level detection device, and particularly to a marine nearshore groundwater level monitoring system, belonging to the technical field of marine nearshore environmental monitoring. Background Art

[0002] Taking tidal flat farmland as an example, there is a great contradiction between the depth of the groundwater level and agricultural water demand. When the groundwater level is too high, that is, the burial depth is less than 1.5 - 1.8 meters, the capillary action of the soil will cause the salt to move upward. After the water evaporates, the salt remains in the surface soil, resulting in an increase in salinization and an increase in the salt concentration in the root zone soil of plants. However, in a high-salt environment, if the soil water potential is reduced, it will lead to difficulty in crop root water absorption, triggering physiological drought, and the plants may wilt. Therefore, the groundwater level in tidal flat farmland is usually preferably controlled at a depth of 1.8 - 2.5 meters.

[0003] The traditional groundwater level monitoring technology is the observation well. The water level in the well is measured by manually lowering a water level gauge such as a tape water level gauge or a float water level gauge. The advantage is low cost, and the disadvantage is low efficiency and inability to monitor in real time. A more advanced monitoring technology is the pressure water level gauge, which uses an underwater pressure sensor to convert water pressure into water level data. The advantage is that it can be laid out for a long time and adapt to tidal dynamic changes. The disadvantage is that it needs to be maintained regularly to prevent salt corrosion and biological attachment. With the development of technology, there are currently many new technologies, such as water level gauges using ultrasonic or radar detection, which can achieve automatic telemetry. There is also satellite remote sensing technology, which detects changes in groundwater storage through gravity inversion or radar interferometry, and is suitable for large-scale and shallow groundwater surveys, but the resolution is affected by soil salinity. There is also the Internet of Things sensor network technology, which uses multi-node pressure sensors and wireless real-time transmission to achieve dynamic early warning through a cloud platform, eliminating the risk of salinization in tidal flat farmland. Additionally, there is fiber optic sensing technology, which uses changes in fiber optic temperature or fiber optic stress to invert the water level. The advantage is anti-electromagnetic interference and suitability for long-distance layout. The defect of the above new technologies is high cost and difficulty in popularization, and some are only used for scientific research or key projects. Summary of the Invention

[0004] The purpose of the present invention is to provide a marine nearshore groundwater level monitoring system that is conducive to popularization and can prevent salt corrosion and biological attachment.

[0005] The technical problems to be solved by the present invention are achieved through the following technical solutions: The system includes a water inlet 1, a glass tube 2, a flood prevention platform 3, a chassis 4, a waterproof baffle 5, an antenna 6, a circuit board 7, a photovoltaic panel 8, a storage battery 10, the ground 13, a cable 14, a saline water power generation group 15, an outgoing line segment 16, an inner tube 17, a spiral tube 18, an incoming line segment 19, a socket 20, pins 21, a dust-proof sponge 22, a seal 23, a saline water surface 24, a sand-proof sponge 25, a modulation circuit 26, capacitors C1 - C9, a diode D, a variable inductor L, a transistor Q1, a field effect transistor Q2, resistors R1 - R8, and a chip U.

[0006] The photovoltaic panel 8 and the saline water power generation group 15 constitute a power supply mechanism. The circuit board 7 includes a power supply voltage stabilization circuit and an LC oscillation circuit. The chip U is a single-chip microcomputer chip or a microcontroller chip with data processing and computing capabilities, and various program modules required for the system to process data are pre-burned in the chip, including the initialization program of the counter / constant counter, the measurement program of the output frequency of the oscillation circuit, and the conversion program of the oscillation frequency to the water level position.

[0007] A flood prevention platform 3 higher than the ground is provided on the ground 13. A circular waterproof baffle 5 is provided on the bottom plate of the chassis 4. The glass tube 2 and the saline water power generation group 15 are provided under the ground 13. The saline water power generation group 15 is composed of eight units and is connected in series. The saline water power generation group 15 and the photovoltaic panel 8 are respectively connected to the storage battery 10 through the cable 14 and their respective directional diodes. The directional diode can isolate the connection between the saline water power generation group 15 and the photovoltaic panel 8 and prevent the voltage of the two from crosstalking from high to low when they are not equal. Most of the glass tube 2 is embedded in the soil, and its top passes through the flood prevention platform 3 and enters the cavity of the chassis 4.

[0008] The glass tube 2 is divided into an outer tube and an inner tube. The top and bottom ends of the outer tube and the inner tube are both connected through a seal 23. A sandwich layer is formed between the outer tube and the inner tube. The sandwich layer of the glass tube is evacuated. A socket 20 is provided at the evacuation nozzle during evacuation. Two pins 21 are provided on the socket 20. The two pins 21 penetrate into the sandwich layer of the glass tube. A spiral tube 18 is wound around the inner tube 17 of the glass tube 2 with enameled wire. The two ends of the spiral tube 18 are respectively connected to the bottom ends of the two pins 21 through its own incoming line segment 19 and outgoing line segment 16. The top ends of the pins 21 are connected to the circuit board 7 through wires. The evacuated sandwich layer of the glass tube can prevent the spiral tube 18 from getting moldy or being soaked in water, so as to eliminate the interference of impurities or moisture on the inductance of the spiral tube 18. A sand-proof sponge 25 is provided at the water inlet 1 at the bottom end of the inner tube 17. The groundwater in the tidal flat farmland seeps into the inner tube 17 through the sand-proof sponge 25 to form a saline water surface 24. The height of the saline water surface 24 can change with the change of the groundwater level. The saline water in the inner tube 17 and the spiral tube 18 constitute a variable inductor L. The saline water and its height serve as variable magnetic media. A breathable dust-proof sponge 22 is provided inside the top end of the inner tube 17.

[0009] When the groundwater level changes, the height of the salt water surface 24 in the spiral tube 18 changes accordingly, that is, the length of the salt water section in the spiral tube 18 is different. The beach groundwater contains salt, and both water and salt are diamagnetic. The change of the salt water surface 24 will cause the change of the inductance of the variable inductor L. When the height of the salt water surface 24 is relatively low, the salt water section is shorter, and the inductance of the variable inductor L is larger. When the height of the salt water surface 24 is relatively high, the salt water section is longer, and the inductance of the variable inductor L is smaller, so that the oscillation circuit has different output frequencies. According to the different output frequencies, through the frequency calculation and numerical conversion of the chip U, the depth value of the groundwater level of the beach farmland can be obtained.

[0010] The capacitor C5, resistor R5 and capacitor C9 form a π-shaped power supply filtering circuit. The capacitors C1-C4, resistors R1-R4, variable inductor L and transistor Q1 constitute a capacitor three-point oscillation circuit. The capacitors C3, C4 and variable inductor L form an LC loop. The output frequency of the oscillation circuit is determined by the LC value of the LC loop. The capacitors C6-C7, resistors R6-R8 and field effect transistor Q2 constitute a follower circuit with a high input impedance. The output signal of the oscillation circuit is coupled to the gate of the field effect transistor Q2 through the capacitor C6. The output signal of the follower circuit is coupled to the diode D through the capacitor C7, and after being half-wave rectified by the diode D and filtered by the capacitor C8 to remove the clutter, it is sent to the chip U. The output end of the chip U is connected to the input end of the modulation circuit 26, and the output end of the modulation circuit 26 is connected to the antenna 6 through a wire. The chip U measures the output frequency of the oscillation circuit and converts it into water level depth information, and then it is modulated into an amplitude modulation signal by the modulation circuit 26 and transmitted through the antenna 6.

[0011] A wireless signal receiving base station needs to be set separately near this system, and several measurement points of this system are set around the base station. The modulation circuits 26 in each system have different modulation frequencies. Different measurement points at different positions are identified according to the different modulation frequencies. The base station takes turns to receive the groundwater level information of several measurement points. After being demodulated respectively, it is processed by a separately installed computer with groundwater level information processing software to obtain the average value of the groundwater level in this area, that is, the depth value of the salt water surface 24 from the ground 13, which provides a basis for the field management of the beach farmland.

[0012] Due to the adoption of the above technical solutions, the advantages and positive effects of the present invention are as follows: The manufacturing cost of the system is moderate, which is conducive to popularization. Compared with manual work, the efficiency is higher, and it can monitor in real time. The spiral tube is encapsulated with vacuum glass tubes, which can prevent salt corrosion and biological adhesion. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described below in conjunction with the drawings and embodiments. The present invention has the following 3 drawings:

[0014] Figure 1 It is a schematic structural diagram of this system.

[0015] Figure 2 It is the structure diagram of the glass tube and the spiral tube of this system.

[0016] Figure 3 It is the circuit schematic diagram of this system.

[0017] The numbers marked in the attached drawings respectively represent as follows:

[0018] 1. Water inlet, 2. Glass tube, 3. Flood prevention platform, 4. Chassis, 5. Waterproof baffle, 6. Antenna, 7. Circuit board, 8. Photovoltaic panel, 9. Bracket, 10. Battery, 11. Top cover, 12. Bolt, 13. Ground, 14. Cable, 15. Salt water power generation group, 16. Outlet line segment, 17. Inner tube, 18. Spiral tube, 19. Inlet line segment, 20. Socket, 21. Pin, 22. Dust-proof sponge, 23. Seal, 24. Salt water surface, 25. Sand-proof sponge, 26. Modulation circuit, C1-C9. Capacitor, D. Diode, L. Variable inductor, Q1. Transistor, Q2. Field effect transistor, R1-R8. Resistor, U. Chip, Vcc. Power supply voltage. Detailed implementation manners

[0019] 1. The system includes a water inlet 1, a glass tube 2, a flood prevention platform 3, a chassis 4, a waterproof baffle 5, an antenna 6, a circuit board 7, a photovoltaic panel 8, a bracket 9, a battery 10, a top cover 11, bolts 12, the ground 13, a cable 14, a salt water power generation group 15, an outlet line segment 16, an inner tube 17, a spiral tube 18, an inlet line segment 19, a socket 20, pins 21, a dust-proof sponge 22, a seal 23, a salt water surface 24, a sand-proof sponge 25, a modulation circuit 26, capacitors C1-C9, a diode D, a variable inductor L, a transistor Q1, a field effect transistor Q2, resistors R1-R8, and a chip U.

[0020] 2. The photovoltaic panel 8 and the salt water power generation group 15 constitute a power supply mechanism. The circuit board 7 includes a power supply voltage stabilization circuit. The chip U is a single-chip microcomputer chip or a microcontroller chip with data processing ability and computing ability, and various program modules required for the system to process data are pre-burned in the chip, including the initialization program of the counter / timer, the measurement program of the output frequency of the oscillation circuit, and the conversion program of the oscillation frequency to the water level position.

[0021] 3. According to Figure 1, on the ground 13, there is a flood prevention platform 3 higher than the ground. The bottom of the flood prevention platform 3 is embedded in the ground 13. There is a chassis 4 on the flood prevention platform 3. The top view of the chassis is circular. The bottom plate of the chassis 4 is connected to the flood prevention platform 3 by bolts 12. There is a circular waterproof baffle 5 on the bottom plate of the chassis 4. Outside the waterproof baffle 5 and on the top of the chassis 4, there is a top cover 11. On the top cover 11, there are an antenna 6, a bracket 9, and a photovoltaic panel 8. The photovoltaic panel 8 is connected to the top cover 11 through the bracket 9. Inside the chassis 4, there is a circuit board 7 and a battery 10. When there is sunlight during the day, the photovoltaic panel 8 provides power for the circuit and charges the battery 10. The saline water power generation group 15 can provide power for the circuit and charge the battery 10 both day and night.

[0022] 4. Below the ground 13, there are glass tubes 2 and a saline water power generation group 15. The saline water power generation group 15 consists of eight units and is connected in series. The saline water power generation group 15 and the photovoltaic panel 8 are respectively connected to the battery 10 through cables 14 and their respective directional diodes. The directional diodes can isolate the connection between the saline water power generation group 15 and the photovoltaic panel 8 and prevent the voltage of the two from crosstalking from high to low when they are not equal. The battery 10 can also provide power for the circuit board 7. Most of the glass tubes 2 are embedded in the soil, and their tops pass through the flood prevention platform 3 and enter the cavity of the chassis 4.

[0023] 5. According to Figure 2 , the glass tube 2 is divided into an outer tube and an inner tube. The tops and bottoms of the outer tube and the inner tube are both connected by seals 23. A sandwich layer is formed between the outer tube and the inner tube. The sandwich layer of the glass tube is evacuated. There is a socket 20 at the evacuation nozzle during evacuation. There are two pins 21 on the socket 20. The two pins 21 penetrate into the sandwich layer of the glass tube. A solenoid 18 is wound around the inner tube 17 of the glass tube 2 with enameled wire. The two ends of the solenoid 18 are respectively connected to the bottoms of the two pins 21 through its own incoming line segment 19 and outgoing line segment 16. The tops of the pins 21 are connected to the circuit board 7 through wires. The evacuated sandwich layer of the glass tube can prevent the solenoid 18 from getting moldy or soaked in water, so as to eliminate the interference of impurities or moisture on the inductance of the solenoid 18. At the water inlet 1 at the bottom end of the inner tube 17, there is a sand-proof sponge 25. The groundwater in the tidal flat farmland seeps into the inner tube 17 through the sand-proof sponge 25 to form a salt water surface 24. The height of the salt water surface 24 can change with the change of the groundwater level. The salt water in the inner tube 17 and the solenoid 18 form a variable inductor L. The salt water and its height serve as variable magnetic media. Inside the top end of the inner tube 17, there is a breathable dust-proof sponge 22.

[0024] 6. According to Figure 3, except that the glass tube 2, the spiral tube 18, and the salt water surface 24 are not on the circuit board 7, the rest of the electronic components are on the circuit board 7. The capacitor C5, resistor R5, and capacitor C9 form a π-shaped power filter circuit. The capacitors C1 - C4, resistors R1 - R4, variable inductor L, and transistor Q1 constitute a capacitor three-point oscillator circuit. The capacitors C3, C4, and variable inductor L form an LC circuit. The output frequency of the oscillator circuit is determined by the LC value of the LC circuit. The capacitors C6 - C7, resistors R6 - R8, and field effect transistor Q2 constitute a follower circuit with a high input impedance. The output signal of the oscillator circuit is coupled to the gate of the field effect transistor Q2 through the capacitor C6. The output signal of the follower circuit is coupled to the diode D through the capacitor C7, and after being half-wave rectified by the diode D and filtered by the capacitor C8 to remove the clutter, it is sent to the chip U. The output end of the chip U is connected to the input end of the modulation circuit 26, and the output end of the modulation circuit 26 is connected to the antenna 6 through a wire. The chip U measures the output frequency of the oscillator circuit, converts it into water level depth information, and then modulates it into an amplitude modulation signal by the modulation circuit 26 and transmits it through the antenna 6.

[0025] 7. When the underground water level changes, the height of the salt water surface 24 in the spiral tube 18 changes accordingly, that is, the length of the salt water section in the spiral tube 18 is different. The beach groundwater contains salt, and both water and salt are diamagnetic. Therefore, the change of the salt water surface 24 will cause the change of the inductance of the variable inductor L. When the height of the salt water surface 24 is lower, the salt water section is shorter, and the inductance of the variable inductor L is larger. When the height of the salt water surface 24 is higher, the salt water section is longer, and the inductance of the variable inductor L is smaller, so that the oscillator circuit has different output frequencies. According to the different output frequencies, through the frequency calculation and numerical conversion of the chip U, the depth value of the underground water level of the beach farmland can be obtained.

[0026] 8. A wireless signal receiving base station needs to be placed separately near this system, and several measurement points of this system are set around the base station. The modulation circuits 26 in each system have different modulation frequencies. According to the different modulation frequencies, the measurement points at different positions are identified. The base station takes turns to receive the underground water level information of several measurement points. After demodulation respectively, it is processed by a separately placed computer equipped with underground water level information processing software to obtain the average value of the underground water level in this area, that is, the depth value of the salt water surface 24 from the ground 13, providing a basis for the field management of the beach farmland.

[0027] 9. The height of the flood prevention platform 3 is about 40 cm, half above the ground and half below the ground. The length of the glass tube 2 is about 2.65 m, with about 5 cm left above the flood prevention platform 3 and about 2.2 m left below the flood prevention platform 3. The spiral tube 18 is wound around the inner tube below the flood prevention platform 3. The outer diameter of the inner tube 17 is about 4 cm, the outer diameter of the outer tube is 6.6 - 6.8 cm, and the glass thickness is 0.3 - 0.4 mm. When there is no salt water in the inner tube 17, the spiral tube 18 is approximately a hollow tube, that is, ignoring the influence of the thin glass. At this time:

[0028] 10. The calculation formula for the inductance of an air-core coil is: L = (μ0N 2 πr 2 ) / l, where:

[0029] L is the inductance, with the unit of Henry (H); μ0 is the permeability of free space, which is 4π×10 -7 H / m; N is the number of turns of the coil;

[0030] r is the radius of a single-turn coil, with the unit of meter (m); l is the length of the coil, with the unit of meter (m);

[0031] Set the number of turns of the coil N = 400 turns, the radius of a single-turn coil r = 2 cm = 0.02 m, and the length of the solenoid 18 l = 2 m. Through the above inductance calculation formula, we get: L = 126.2 μH;

[0032] For the LC circuit, its frequency is: f0 = 1 / [2π(LC) 1 / 2 , set C3 = C4 = 0.47 μF, then C 总 = 0.47 μF÷2 = 0.235 μF. Through the above frequency calculation formula, we get: f0 = 29.23 KHz.

[0033] 11. The modulation frequency of the modulation circuit 26 is in the radio amateur band, which is 28.0 - 29.7 MHz. The resistance value of R6 is 2.2 MΩ. The model of Q1 is 2SC1815 or 9014, the model of Q2 is 2N7002 or CJ7002, and the diameter of the enameled wire is 0.5 mm. The saline power generation group 15 is a simple saline battery, which uses saline as the electrolyte and generates electricity through the redox reaction of metal electrodes. Its anode is an active metal, with the material of magnesium or zinc, and the cathode is an inert material, with the material of carbon or copper. The burial depth of the saline power generation group 15 is 1.5 - 1.8 m, the voltage generated by each unit is 0.7 - 1.2 V, and the total output voltage after series connection is 5.6 - 9.6 V. The no-load voltage of the storage battery 10 is 4.8 V.

[0034] 12. To make Figure 3 it concise and clear, the power supply voltage stabilization circuit and its connection with other circuits are not drawn. The model of the chip is PCI 16F or STM 32. Since its technology is very mature and has wide applications, the specific circuit, working principle, programming, and burning are introduced in many books and materials, and a lot of relevant information can also be found online. Moreover, the content in this regard is not within the protection scope of this case, so it will not be elaborated in this specification.

Claims

1. A marine near - surface groundwater level monitoring system, comprising an inlet (1), a glass tube (2), a flood - proof platform (3), a chassis (4), a waterproof baffle (5), an antenna (6), a circuit board (7), a photovoltaic panel (8), a storage battery (10), the ground (13), a cable (14), a saline - water power generation group (15), an outlet line segment (16), an inner tube (17), a spiral tube (18), an inlet line segment (19), a socket (20), pins (21), a dust - proof sponge (22), a seal (23), a saline - water surface (24), a sand - proof sponge (25), a modulation circuit (26), capacitors C1 - C9, a diode D, a variable inductor L, a transistor Q1, a field - effect transistor Q2, resistors R1 - R8, and a chip U; The photovoltaic panel (8) and the saline - water power generation group (15) constitute a power supply mechanism. The circuit board (7) includes a power supply voltage - stabilizing circuit and an LC oscillation circuit. The chip U is a single - chip microcomputer chip or a micro - control chip with data - processing and computing capabilities, and various program modules required for the device to process data are pre - burned in the chip, including the initialization program of the counter / timer, the measurement program of the output frequency of the oscillation circuit, and the conversion program of the oscillation frequency to the water - level position; It is characterized in that: A flood - proof platform (3) higher than the ground is provided on the ground (13). A circular waterproof baffle (5) is provided on the bottom plate of the chassis (4). A glass tube (2) and a saline - water power generation group (15) are provided below the ground (13). The saline - water power generation group (15) consists of eight units and is connected in series. The saline - water power generation group (15) and the photovoltaic panel (8) are respectively connected to the storage battery (10) through cables (14) and their respective directional diodes. The directional diodes can isolate the connection between the saline - water power generation group (15) and the photovoltaic panel (8) and prevent the voltage of the two from cross - interfering from high to low when they are not equal. Most of the glass tube (2) is embedded in the soil, and its top passes through the flood - proof platform (3) and enters the cavity of the chassis (4); The glass tube (2) is divided into an outer tube and an inner tube. The top and bottom ends of the outer tube and the inner tube are both connected by seals (23). A sandwich layer is formed between the outer tube and the inner tube. The sandwich layer of the glass tube is evacuated. A socket (20) is provided at the pumping nozzle during evacuation. Two pins (21) are provided on the socket (20). The two pins (21) penetrate into the sandwich layer of the glass tube. A solenoid (18) is wound around the inner tube (17) of the glass tube (2) with enameled wire. The two ends of the solenoid (18) are respectively connected to the bottom ends of the two pins (21) through lead-in segments (19) and lead-out segments (16). The top ends of the pins (21) are connected to the circuit board (7) through wires. The evacuated sandwich layer of the glass tube can prevent the solenoid (18) from getting moldy or soaked in water, so as to eliminate the interference of impurities or moisture on the inductance of the solenoid (18). A sand-proof sponge (25) is provided at the water inlet (1) at the bottom end of the inner tube (17). The groundwater in the tidal flat farmland seeps into the inner tube (17) through the sand-proof sponge (25) to form a salt water surface (24). The height of the salt water surface (24) can change with the change of the groundwater level. The salt water in the inner tube (17) and the solenoid (18) form a variable inductor L. The salt water and its height serve as variable magnetic media. A breathable dust-proof sponge (22) is provided inside the top end of the inner tube (17); When the groundwater level changes, the height of the salt water surface (24) in the solenoid (18) changes accordingly, that is, the length of the salt water section in the solenoid (18) is different. The tidal flat groundwater contains salt. Both water and salt are diamagnetic. The change of the salt water surface (24) will cause the change of the inductance of the variable inductor L. When the height of the salt water surface (24) is relatively low, the salt water section is shorter and the inductance of the variable inductor L is larger. When the height of the salt water surface (24) is relatively high, the salt water section is longer and the inductance of the variable inductor L is smaller, so that the oscillation circuit has different output frequencies. According to the different output frequencies, through the frequency calculation and numerical conversion of the chip U, the depth value of the groundwater level in the tidal flat farmland can be obtained.

2. The marine near-surface groundwater level monitoring system according to claim 1, wherein: The capacitor C5, resistor R5 and capacitor C9 form a π-shaped power supply filter circuit. The capacitors C1 - C4, resistors R1 - R4, variable inductor L and transistor Q1 constitute a capacitor three-point oscillation circuit. The capacitors C3, C4 and variable inductor L form an LC loop. The output frequency of the oscillation circuit is determined by the LC value of the LC loop. The capacitors C6 - C7, resistors R6 - R8 and field effect transistor Q2 constitute a follower circuit with a high input impedance. The output signal of the oscillation circuit is coupled to the gate of the field effect transistor Q2 through the capacitor C6. The output signal of the follower circuit is coupled to the diode D through the capacitor C7. After being half-wave rectified by the diode D and filtered by the capacitor C8 to remove the clutter, it is sent to the chip U. The output end of the chip U is connected to the input end of the modulation circuit (26). The output end of the modulation circuit (26) is connected to the antenna (6) through a wire.

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