Farmland leaching layering monitoring well system

Abstract

The utility model discloses a farmland leaching layering monitoring well system which comprises a layering monitoring well which comprises an upper well pipe, a middle well pipe and a lower well pipe. The root layer is provided with an upper well pipe, the aeration zone is provided with a middle well pipe, the aquifer is provided with a lower well pipe, and the underground water level is higher than the bottom surface of the lower well pipe. The pipe diameters of the upper, middle and lower well pipes are sequentially reduced. The upper well casing and the middle well casing are connected through connecting plates, and the middle well casing and the lower well casing are connected through connecting plates. At least one soil parameter detection sensor is arranged in the root layer, the aeration zone and the water-bearing layer, a water quality sensor is arranged in underground water in the lower well pipe, and a transmission cable led out of the soil parameter detection sensor penetrates through the well wall of the layered monitoring well, then is converged with a transmission cable led out of the water quality sensor and extends upwards to be connected with an overground monitoring instrument. And the plate for manufacturing the connecting plate is the same as the pipe of the adjacent corresponding well casing. The underground parameter monitoring device is designed according to a root layer-aeration zone-aquifer shallow critical stratum structure, and underground parameters can be comprehensively and accurately monitored in the farmland leaching process.

Description

Technical Field

[0001] The utility model relates to a farmland leaching layered monitoring well system, belonging to the technical field of farmland leaching process monitoring. Background Art

[0002] Monitoring the leaching process of farmland is a crucial link in crop supervision and food income generation. It is also a key task that needs to be carried out in the evaluation of fertilizer effects, pesticide pollution, soil remediation and other topics. The leaching process of farmland is complex, and the parameters that need to be monitored are diverse. However, the current monitoring methods at home and abroad generally have a low degree of automation. For example, with regard to the monitoring of leaching water, most scientific research institutes and production lines still use leaching trays or leaching barrels to obtain parameters. For another example, the water-proof treatment of the soil layer on site is basically missing, or it is usually solved with a simple waterproof cloth, so that the data obtained is not sufficient for reference. In addition, monitoring points such as soil nitrogen, conductivity, and moisture content are generally arranged in artificially excavated pits. Monitoring points are usually arranged in the soil based on experience. It can be seen that the scientific nature of the arrangement methods and processes is insufficient, which can easily lead to a lack of comparability of the monitoring data obtained, causing great uncertainty in the establishment of later models.

[0003] With the continuous development of automation technology, computer technology and drilling technology, smart agricultural monitoring has attracted more and more attention. Currently, the more popular mode is the "root layer-vadose zone-aquifer" shallow critical stratum underground full-profile monitoring of farmland leaching. It can be seen that for the shallow critical stratum structure of "root layer-vadose zone-aquifer", it is an urgent problem to design a technical solution that can comprehensively and accurately monitor underground parameters during farmland leaching. Utility Model Content

[0004] The purpose of the utility model is to provide a farmland leaching stratification monitoring well system, which is designed for the shallow critical stratum structure of "root layer-vadose zone-aquifer", can comprehensively and accurately monitor underground parameters during farmland leaching, and is suitable for promotion.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A farmland leaching stratified monitoring well system, comprising a stratified monitoring well arranged in farmland soil, wherein: the stratified monitoring well comprises an upper well pipe, a middle well pipe and a lower well pipe arranged from top to bottom; the upper well pipe is arranged in the root layer between the surface and the vadose zone, the middle well pipe is arranged in the vadose zone between the root layer and the aquifer, the lower well pipe is arranged in the aquifer below the vadose zone, and the groundwater level of the aquifer is higher than the bottom surface of the lower well pipe; the diameters of the upper well pipe, the middle well pipe and the lower well pipe are reduced in sequence, so that the well wall of the stratified monitoring well is in a step shape; the upper well pipe and the middle well pipe, and the middle well pipe and the lower well pipe are connected by a connecting plate arranged along the radial direction of the stratified monitoring well; the root layer , at least one soil parameter detection sensor is provided in each of the aeration zone and the aquifer, a water quality sensor is provided in the groundwater in the lower well pipe, and the transmission cable led out of the soil parameter detection sensor passes through the well wall of the stratified monitoring well and then merges with the transmission cable led out of the water quality sensor and extends upward to the surface to be connected with the ground monitoring instrument located on the surface; the soil parameter detection sensor is any one of a total nitrogen sensor, an ammonia nitrogen sensor, a soil moisture content sensor, a temperature sensor, a soil EH sensor or a soil water potential sensor, or a combination of any several of them; the plate material for making the connecting plate is the same as the pipe material of the corresponding well pipe adjacent to it, wherein the well pipe is the upper well pipe, the middle well pipe or the lower well pipe.

[0007] The advantages of the utility model are:

[0008] The utility model is designed for the shallow critical stratum structure of "root layer-vadose zone-aquifer", and can comprehensively and accurately monitor underground parameters during the leaching process of farmland, such as the leaching amount, the migration of soil elements such as nitrogen, phosphorus and potassium, and the soil permeability. Compared with the existing technology, the utility model solves the problems of large disturbance to the original soil, inaccurate monitoring results, and data lag, and achieves the purpose of automatic stratified monitoring of the entire underground profile of the farmland root layer-vadose zone-aquifer, which is conducive to the development of agricultural modernization. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of a farmland leaching stratification monitoring well system of the utility model.

[0010] Figure 2 This is a schematic diagram of the well excavation.

[0011] Figure 3 It is a schematic structural diagram of the first embodiment of the stratified monitoring well.

[0012] Figure 4 It is a schematic structural diagram of the second embodiment of the stratified monitoring well.

[0013] Figure 5It is a schematic structural diagram of the third embodiment of the stratified monitoring well.

[0014] Figure 6 It is a schematic structural diagram of the fourth embodiment of the stratified monitoring well. DETAILED DESCRIPTION

[0015] like Figures 1 to 6 As shown, the utility model proposes a farmland leaching stratified monitoring well system, which includes a stratified monitoring well 10 arranged in the farmland soil, wherein: the stratified monitoring well 10 includes an upper well pipe 13, a middle well pipe 14 and a lower well pipe 15 arranged from top to bottom; the upper well pipe 13 is arranged in the root layer 83 between the surface 84 and the vadose zone 82, the middle well pipe 14 is arranged in the vadose zone 82 between the root layer 83 and the aquifer 81, and the lower well pipe 15 is arranged in the aquifer 81 below the vadose zone 82, and the groundwater level of the aquifer 81 is higher than the bottom surface of the lower well pipe 15; the pipe diameters (pipe inner diameters) of the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 are reduced in sequence, so that the well wall of the stratified monitoring well 10 is stepped; a connecting plate arranged along the radial direction (or horizontal direction) of the stratified monitoring well 10 is provided between the upper well pipe 13 and the middle well pipe 14, and between the middle well pipe 14 and the lower well pipe 15. 16 is connected; at least one soil parameter detection sensor 20 is provided in each of the root layer 83, the aeration zone 82 and the aquifer 81; a water quality sensor 30 is provided in the groundwater 85 in the lower well pipe 15; a transmission cable 40 led out of the soil parameter detection sensor 20 passes through the well wall of the stratified monitoring well 10, merges with the transmission cable 40 led out of the water quality sensor 30 and extends upward to the ground surface 84 to be connected with the ground monitoring instrument 50 located on the ground surface 84; the soil parameter detection sensor 20 is any one or a combination of any several of a total nitrogen sensor, an ammonia nitrogen sensor, a soil moisture content sensor, a temperature sensor, a soil EH sensor or a soil water potential sensor (not limited); the plate material for making the connecting plate 16 is the same as the pipe material of the corresponding well pipe adjacent (or closely adjacent) thereto, wherein the well pipe is an upper well pipe 13, a middle well pipe 14 or a lower well pipe 15.

[0016] like Figure 1 and Figure 2 , the well location of the stratified monitoring well 10 is located in the farmland. The utility model is mainly applicable to shallow critical strata, which are composed of three layers from top to bottom: the root layer 83, the aeration zone 82, and the aquifer 81. The top surface of the root layer is the ground surface 84, and the groundwater 85 is in the aquifer 81. The groundwater level will not be higher than the aquifer 81. Therefore, the well depth of the stratified monitoring well 10 should be determined according to the groundwater level in the aquifer 81, that is, the groundwater level should be in the lower well pipe 15. In other words, the height of the upper well pipe 13 should be set according to the height of the root layer 83, the height of the middle well pipe 14 should be set according to the height of the aeration zone 82, and the height of the lower well pipe 15 should be set according to the height of the groundwater 85 in the aquifer 81. Figures 3 to 6As shown, the layered monitoring well 10 of the utility model is a three-layer vertical well structure (or a three-level vertical well structure), the top layer is the first layer, the middle layer is the second layer, and the bottom layer is the third layer. The diameters (inner diameters) of the three layers of well pipes arranged vertically gradually decrease from top to bottom in a step-like shape, and the diameters are R1, R2, and R3 respectively. Correspondingly, the wall 12 of the wellbore 11 excavated in the farmland is also in a step-like shape, as shown in FIG. Figure 2 .

[0017] In actual implementation, the stratified monitoring well 10 is formed by excavating three layers of wellbores at the well location using a rotary drilling process and sequentially laying a lower well pipe 15, a middle well pipe 14 and an upper well pipe 13 in the wellbore using a sinking pipe laying process, wherein the lower well pipe 15, the middle well pipe 14 and the upper well pipe 13 are in close contact with the surrounding farmland soil.

[0018] Specifically, a three-layer wellbore 11 with a stepped hole wall 12 is first excavated at the well formation location in the farmland using a rotary drilling process, and then a lower well pipe 15, a middle well pipe 14 and an upper well pipe 13 are sequentially laid in the lower, middle and upper layers of the wellbore 11 using a sinking pipe laying process. The outer walls of the lower well pipe 15, the middle well pipe 14 and the upper well pipe 13 are in close contact with the hole wall 12 without any gap, forming a layered monitoring well 10.

[0019] Here, the rotary drilling process and the sunken pipe laying process are existing technologies in this field, but these two technologies are used for farmland leaching monitoring for the first time, which is of great significance.

[0020] The general practice of rotary drilling hole-forming technology is to use a barrel drill bucket. After the drill rig is in place, adjust the verticality of the drill rod, inject the prepared mud, and then drill. When the drill bit drops to the predetermined depth, rotate the drill bucket and apply pressure to squeeze the soil into the drill bucket. When the drill rig instrument shows that the barrel is full, the bottom of the drill bucket is closed, and the drill bucket is lifted to unload the soil to the stacking location. During the drilling rig construction process, it should be ensured that the mud surface is never lower than the bottom of the casing to ensure the stability of the hole wall. Through the rotation of the drill bucket, soil cutting, lifting, unloading soil and mud supporting the hole wall, the cycle is repeated until the hole is formed. During construction, the relative density of the mud is 1.02~1.10, the viscosity is 18~22Pa·s, the sand rate is ≤4%, the mud skin thickness is <2mm, and the pH value is greater than 7. During the construction process, the various performance indicators of the mud poured after the hole is cleaned should be tested at any time to ensure the supporting effect of the mud on the hole wall and avoid construction accidents.

[0021] The sinking pipe laying process adopted by the utility model ensures close contact between the well pipe and the soil. Different from the method of filling gravel and clay balls in the annular gap of geological drilling holes, the sinking pipe laying process relies on the well pipe's own gravity and external pressure to press the well pipe into the formation, so the hole size of the rotary drilling hole-making process should be slightly smaller than the outer diameter of the well pipe.

[0022] like Figure 2The apertures of the three-layer wellbore 11 excavated by the rotary drilling process are, from top to bottom, the first opening aperture, the second opening aperture and the third opening aperture, which are slightly smaller than the outer diameters of the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15, respectively.

[0023] In the present invention, the well pipes are divided into upper well pipes 13, middle well pipes 14 and lower well pipes 15 due to different positions. Their pipe materials can be the same or different, depending on the actual monitoring needs. They are connected by connecting plates 16, which are annular and horizontally arranged between the upper and lower layers. For example, the connecting plate 16 connecting the upper well pipe 13 and the middle well pipe 14 is located on the adjacent surface between the root layer 83 and the aeration zone 82, and the connecting plate 16 connecting the middle well pipe 14 and the lower well pipe 15 is located on the adjacent surface between the aeration zone 82 and the aquifer 81.

[0024] In the present invention, the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 are all referred to as well pipes, and the pipe materials of the three can be the same or different. In the present invention, the pipe material of the well pipe is a water-proof pipe or a seepage pipe. In actual design, the diameters of the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 can be determined according to factors such as the type, quantity and position of the soil parameter detection sensor 20.

[0025] Preferably, the diameter R1 of the upper well pipe 13 does not exceed 1.5 meters, and the diameter R2 of the middle well pipe 14 and the diameter R3 of the lower well pipe 15 can be determined according to actual monitoring requirements.

[0026] For example, if Figure 3 In the figure, the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 are respectively shown by dotted lines, dotted lines and double dotted lines. It can be seen from the figure that the connecting plate 16 connecting the upper well pipe 13 and the middle well pipe 14 is made of the pipe material of the upper well pipe 13, and the connecting plate 16 connecting the middle well pipe 14 and the lower well pipe 15 is made of the pipe material of the middle well pipe 14. Here, the pipe material of the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 is preferably a watertight pipe, but of course it is not limited.

[0027] Figure 3 The stratified monitoring well 10 shown realizes a full-profile stratified monitoring. In actual implementation, by arranging corresponding types of soil parameter detection sensors 20 in different layers, independent monitoring of "one hole and multiple layers" can be realized to obtain monitoring data with significant contrast. At the same time, soil parameter detection sensors 20 can be arranged at different radial depths to obtain the seepage law in the horizontal direction of the stratum, providing reliable data support for the establishment of a multi-dimensional underground leaching model.

[0028] In the utility model, the watertight pipe is made of PVC pipe material or HDPE pipe material, and the seepage pipe is made of gravel-attached pipe material.

[0029] Specifically, in the present utility model, the watertight pipe is also called a solid pipe, and its main function is to cut off the seepage in all directions in the soil. The material of the watertight pipe can be designed according to the requirements of water-blocking performance and stress strength. According to the actual needs of farmland leaching monitoring, the utility model preferably uses PVC pipes or HDPE pipes to make watertight pipes. In particular, for small diameter (0-200mm) application environments, PVC-U material can be selected for production, with a tensile strength of not less than 31MPa, a compressive strength of not less than 40MPa, and a softening temperature of 82.5°C. For large diameter (200mm-1600mm) application environments, HDPE material can be selected for production, with reasonable wall thickness and diameter, a tensile strength of not less than 60MPa, a compressive strength of not less than 80MPa, and a softening temperature of 130°C. The watertight pipe has good anti-aging, anti-geological settlement, flame retardancy, and anti-static properties, and its performance does not change over time, and is particularly suitable for long-term monitoring of soil environment.

[0030] In the present invention, the seepage pipe is also called a water filter pipe, and its main function is to achieve the required permeability. Here, since the layered monitoring well 10 needs to be closely combined with the soil when the soil parameter detection sensor 20 is arranged on the wall of the well to achieve in-situ monitoring, the traditional process of clay balls and filter materials on the outer wall of the seepage pipe will affect the combination of the sensor and the soil. Therefore, the present invention selects a gravel-attached pipe as a seepage pipe, and adopts the following sinking pipe laying process to achieve in-situ monitoring of soil leaching.

[0031] The gravel pipe is an existing pipe in the art, which is composed of a substrate, gravel and an adhesive. The substrate is a PVC-U sheet with uniform circular holes. When used for well pipes, the substrate is cylindrical, and when used as a connecting plate, the substrate is an annular flat plate. The thickness of the substrate is determined according to the stress requirements. The gravel material is selected from ceramic balls, which are spherical and made of clay after crushing, extrusion and firing. The main components include silicon dioxide, ferric oxide and aluminum oxide. The ceramic balls are rough in shape and full of tiny pores. During production, the ceramic balls are regularly attached to the outer wall of the substrate through an adhesive. The permeability of the seepage pipe is certain, and the permeability can be adjusted by the size of the ceramic balls, the thickness of the adhesive, etc. The ceramic balls are fixed on the substrate by an adhesive to form a gravel pipe, which has the advantages of light weight, high strength, immersion resistance, and no pollution. The adhesive should have the characteristics of high bonding strength, strong corrosion resistance, and controllable curing speed. Epoxy resin, curing agent or diluent is selected as the adhesive. In addition, the optimal ratio of ceramic balls and adhesive can be reasonably determined based on the construction time and requirements such as pipe strength and permeability coefficient.

[0032] In actual design, the permeability of the seepage pipe is determined by its permeability coefficient. The permeability coefficient of the seepage pipe should be consistent with or in a certain proportion to the soil permeability coefficient of the adjacent layer. After the permeability coefficient of the seepage pipe is designed, the seepage pipe is finally determined by adjusting the ratio of the ceramic balls and adhesive of the gravel pipe.

[0033] In actual design, windows (or openings) (not shown in the figure) are opened on the side walls of the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15, that is, a window structure is designed on each well pipe, and the transmission cable 40 led out of each soil parameter detection sensor 20 arranged underground in the farmland extends along the radial direction of the layered monitoring well 10 and passes through the window on the corresponding well pipe and then merges with the transmission cable 40 led out of the water quality sensor 30, so as to extend upward to the ground surface 84 together.

[0034] In actual application, the soil parameter detection sensor 20 is arranged near the outside of the hole wall 12. The arrangement position of each soil parameter detection sensor 20 can be reasonably designed according to the actual monitoring needs without limitation. Figure 1 For example, all soil parameter detection sensors 20 can be arranged on the same vertical line, so that the leaching conditions of different layers can be obtained and compared through the soil parameter detection sensors 20 arranged at each layer. For another example, for the window of the same well pipe, each soil parameter detection sensor 20 is arranged at different radial depths, so that the seepage law of the layer in the radial direction or horizontal direction can be obtained.

[0035] based on Figure 3 The layered monitoring well 10 shown in the figure, the utility model also proposes some modified designs.

[0036] like Figure 4 The middle well pipe 14 and the lower well pipe 15 both extend upward to the ground surface 84.

[0037] For example, refer to Figure 4 In the figure, the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 are respectively shown by dotted lines, dotted lines and double dotted lines. It can be seen from the figure that the connecting plate 16 connecting the upper well pipe 13 and the middle well pipe 14 is made of the pipe material of the upper well pipe 13, the connecting plate 16 connecting the middle well pipe 14 and the lower well pipe 15 is made of the pipe material of the middle well pipe 14, and the middle well pipe 14 extends upward to the ground surface 84, and the lower well pipe 15 also extends upward to the ground surface 84.

[0038] Here, if the pipe material of the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 is selected as a watertight pipe (solid pipe), the layered monitoring well 10 forms three independent wells, and the watertight pipe shields the interference in the radial direction. Further, the three independent wells are backfilled with original soil under the same conditions, and the in-situ monitoring of multi-dimensional independent soil layers can be realized, that is, the comparison of leaching conditions at different depths in the same well, the comparison of leaching conditions at the same depth in different wells, and the comparison of gradient leaching conditions in three wells can be realized.

[0039] In addition, the pipe materials of the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 can be reasonably designed according to monitoring requirements. For example, the upper well pipe 13 uses a seepage pipe, the middle well pipe 14 and the lower well pipe 15 use a water-proof pipe (solid pipe), and so on, without limitation.

[0040] like Figure 5 When the plate material for making the connecting plate 16 is a seepage pipe, the connecting plate 16 covers the bottom surface of the corresponding adjacent well pipe thereon to separate the two adjacent well pipes above and below.

[0041] For example, refer to Figure 5 In the figure, the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 are respectively shown by dotted lines, dotted lines and double dotted lines. It can be seen from the figure that the connecting plate 16 connecting the upper well pipe 13 and the middle well pipe 14 is made of seepage pipe and covers the bottom surface of the upper well pipe 13, separating the upper well pipe 13 from the middle well pipe 14. Similarly, the connecting plate 16 connecting the middle well pipe 14 and the lower well pipe 15 is made of seepage pipe and covers the bottom surface of the middle well pipe 14, separating the middle well pipe 14 from the lower well pipe 15.

[0042] Figure 5 The layered monitoring well 10 shown can be used to monitor the vertical seepage rate and seepage volume. The existing methods in this industry are the "leaching tube" and "leaching tray" water volume monitoring methods, which use capillaries to pump the leaching water to the surface to calculate the leaching volume. It has two disadvantages: first, the monitoring environment is not intuitive, and it is impossible to verify whether all the water has been pumped to the ground; second, waterproof plastics or waterproof curtains are generally used to shield the horizontal seepage of the formation. This waterproof material is easily damaged, has a short service life, and the waterproof effect cannot be verified. Therefore, the leaching volume measured by the existing methods is not accurate enough. Compared with the existing methods, Figure 5 The stratified monitoring well 10 shown does not have the above-mentioned disadvantages. Figure 5 The upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 are waterproof pipes, which can effectively shield the interference in the radial direction and can be reused repeatedly. In addition, the connecting plate 16 effectively isolates the upper and lower adjacent layers, simulating the actual soil layer permeability rate and seepage volume. In actual production, the upper well pipe 13 and the connecting plate 16 connected to the bottom surface are integrated, and the middle well pipe 14 and the connecting plate 16 connected to the bottom surface are integrated, so they can be directly taken out and recovered from the well, and the seepage volume can be intuitively calculated.

[0043] In addition, if Figure 6 , the upper well pipe 13, the middle well pipe 14 and the lower well pipe 15 are backfilled with original soil 17 to form a backfill monitoring well.

[0044] For example, Figure 4 The three independent wells formed by the layered monitoring well 10 shown can be backfilled with original soil to form backfill monitoring wells.

[0045] For example, refer to Figure 6 , Figure 6The stratified monitoring well 10 is shown in Figure 3 The original soil 17 is backfilled on the foundation to form a backfill monitoring well. The backfill monitoring well can meet the absolute in-situ monitoring requirements and can realize the comparison between in-situ monitoring and backfill monitoring. In actual implementation, after the corresponding soil parameter detection sensor 20 is arranged on the outside of the hole wall 12, the original soil is backfilled, and the same type of sensor is arranged at the same depth of the backfill space. The difference between backfill monitoring and in-situ monitoring can be evaluated by comparing the data obtained by the sensor at the same depth.

[0046] Here, the traditional practice is to dig a pit and then backfill it. This practice is irreversible, and it is difficult to determine whether the backfill monitoring is true in-situ monitoring. The relationship between backfill monitoring and in-situ monitoring is also difficult to scientifically evaluate. Figure 6 The backfill monitoring well shown solves the shortcomings of traditional practices well.

[0047] In the present invention, the water quality sensor 30 is used to monitor the impact of farmland leaching on groundwater 85, and it can detect conventional water quality parameters in groundwater 85 in the aquifer 81, such as conductivity, pH value, dissolved oxygen, and redox potential. The soil parameter detection sensor 20 is used to monitor the content of soil elements during farmland leaching to reflect the migration law.

[0048] The soil parameter detection sensor 20 and the water quality sensor 30 are both existing sensors in the art.

[0049] The utility model realizes layered monitoring of different soil layers through the design of the layered monitoring well 10. The height of the well pipe in each layer is determined according to the thickness of the layer. The number and position of the sensors in each layer and the diameter of the well pipe in each layer are determined according to the monitoring requirements. The layout method and material of the well pipe in each layer are determined according to the penetration requirements to be monitored.

[0050] In the present invention, the ground monitoring instrument 50 is mainly used to receive and store the data fed back by each sensor, perform simple processing on the data, and upload the processed data to the remote monitoring center.

[0051] The layered monitoring well 10 designed in the utility model provides an underground full-profile layered monitoring method, which can truly reflect the impact of farmland leaching process on soil and groundwater. Various types of soil parameter detection sensors 20 arranged in different layers realize the monitoring of the content of multiple soil elements, and achieve the monitoring of the migration law of soil elements in the farmland leaching process. The water quality sensor 30 set in the groundwater 85 realizes the monitoring of the impact of the farmland leaching process on the groundwater 85. Each monitoring data is transmitted to the ground monitoring instrument 50 through the transmission cable 40, and uploaded to the remote monitoring center by the ground monitoring instrument 50 to complete the monitoring task, providing data support for the establishment of a multi-dimensional underground leaching model.

[0052] The advantages of the utility model are:

[0053] The utility model is designed for the shallow critical stratum structure of "root layer-vadose zone-aquifer", and can comprehensively and accurately monitor underground parameters during the leaching process of farmland, such as the leaching amount, the migration of soil elements such as nitrogen, phosphorus and potassium, and the soil permeability. Compared with the existing technology, the utility model solves the problems of large disturbance to the original soil, inaccurate monitoring results, and data lag, and achieves the purpose of automatic stratified monitoring of the entire underground profile of the farmland root layer-vadose zone-aquifer, which is conducive to the development of agricultural modernization.

[0054] The above are preferred embodiments of the present invention and the technical principles used therein. For those skilled in the art, without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformation, simple replacement, etc. based on the technical solution of the present invention are within the protection scope of the present invention.

Claims

1. A farmland leaching stratification monitoring well system, characterized in that: The invention comprises a stratified monitoring well arranged in farmland soil, wherein: the stratified monitoring well comprises an upper well pipe, a middle well pipe and a lower well pipe arranged from top to bottom; the upper well pipe is arranged in the root layer between the surface and the aeration zone, the middle well pipe is arranged in the aeration zone between the root layer and the aquifer, the lower well pipe is arranged in the aquifer below the aeration zone, and the groundwater level of the aquifer is higher than the bottom surface of the lower well pipe; the diameters of the upper well pipe, the middle well pipe and the lower well pipe are reduced in sequence so that the well wall of the stratified monitoring well is in a step shape; the upper well pipe and the middle well pipe, and the middle well pipe and the lower well pipe are connected by connecting plates arranged along the radial direction of the stratified monitoring well; the root layer, the aeration zone, At least one soil parameter detection sensor is provided in each of the aquifers, and a water quality sensor is provided in the groundwater in the lower well pipe. The transmission cable led out of the soil parameter detection sensor passes through the well wall of the stratified monitoring well and then merges with the transmission cable led out of the water quality sensor and extends upward to the surface to be connected with the ground monitoring instrument located on the surface; the soil parameter detection sensor is any one of a total nitrogen sensor, an ammonia nitrogen sensor, a soil moisture content sensor, a temperature sensor, a soil EH sensor or a soil water potential sensor, or a combination of any of the above; the plate material for making the connecting plate is the same as the pipe material of the corresponding well pipe adjacent thereto, wherein the well pipe is the upper well pipe, the middle well pipe or the lower well pipe.

2. The farmland leaching stratification monitoring well system according to claim 1, characterized in that: The stratified monitoring well is formed by excavating three layers of wellbores at the well formation location using a rotary drilling process and sequentially laying the lower well pipe, the middle well pipe and the upper well pipe in the wellbore using a sinking pipe laying process, wherein the lower well pipe, the middle well pipe and the upper well pipe are in close contact with the surrounding farmland soil.

3. The farmland leaching stratification monitoring well system according to claim 2, characterized in that: The well pipe is a watertight pipe or a seepage pipe, wherein: the watertight pipe is made of PVC pipe or HDPE pipe, and the seepage pipe is made of gravel-attached pipe; Windows are provided on the side walls of the upper well pipe, the middle well pipe and the lower well pipe, and the transmission cables led out of each soil parameter detection sensor extend along the radial direction of the layered monitoring well and pass through the corresponding window on the well pipe and then merge with the transmission cable led out of the water quality sensor to extend upward to the surface together, wherein: all the soil parameter detection sensors are arranged on the same vertical line, or, for the windows of the same well pipe, the soil parameter detection sensors are arranged at different radial depths.

4. The farmland leaching stratification monitoring well system according to claim 3, characterized in that: The middle well pipe and the lower well pipe both extend upward to the ground surface.

5. The farmland leaching stratification monitoring well system according to claim 3, characterized in that: When the plate material for making the connecting plate is a seepage pipe, the connecting plate is spread over the bottom surface of the corresponding adjacent well pipe thereon to separate two adjacent well pipes above and below.

6. The farmland leaching stratification monitoring well system according to claim 3 or 4, characterized in that: The upper well pipe, the middle well pipe and the lower well pipe are backfilled with original soil to form a backfill monitoring well.

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