An experimental system for simulating the process of vadose zone moisture transport under the influence of surface water bodies

Abstract

This invention discloses an experimental system for simulating the vadose zone moisture transport process under the influence of surface water bodies. The system includes: a host computer module, a water supply unit, a flow collection unit, and, from top to bottom, an artificial rainfall unit, a surface water simulation unit, a vadose zone simulation unit, and a groundwater control unit connected sequentially. The host computer module receives data from each unit; the artificial rainfall unit adjusts rainfall intensity and duration; the surface water simulation unit simulates surface water bodies; the vadose zone simulation unit simulates different soil types; the groundwater control unit simulates groundwater; the water supply unit supplies water to the artificial rainfall unit, the surface water simulation unit, and the groundwater control unit; and the flow collection unit collects water overflowing from the surface water simulation unit and the groundwater control unit. The system can accurately reflect the vadose zone moisture transport patterns under the influence of surface water bodies.

Description

Technical Field

[0001] This invention relates to the fields of hydrogeology and soil monitoring, and in particular to an experimental system for simulating the vadose zone water transport process under the influence of surface water bodies. Background Technology

[0002] The vadose zone, located between the Earth's surface and the groundwater layer, is an unsaturated zone that serves as a conduit for material exchange and water transport between the surface and groundwater, and is a crucial link between the atmosphere, surface hydrosphere, and groundwater. Water transport within the vadose zone is influenced by various factors, such as stratigraphic lithology, topography, climate, and surface water accumulation. Exploring the temporal and spatial distribution of water in the vadose zone and studying its transport mechanisms are of great significance for understanding the conversion process between surface water and groundwater, accurately assessing water resources, and predicting the extent of soil pollution. Utilizing physical models to investigate the water transport patterns within the vadose zone is an effective means of scientific research on this zone. Soil column devices, due to their simple preparation and convenient operation, have been widely used in simulating vadose zone studies. However, conventional soil column apparatuses also have certain limitations. First, conventional soil column apparatuses are integrated structures, making it inconvenient to change soil layers. When it is necessary to investigate the properties of the vadose zone in different soil layers, this will prolong the experimental cycle and increase the cost. Second, conventional soil column apparatuses mostly use constant head surface water to simulate surface water accumulation, which is not suitable for simulating the water transport process in the vadose zone of surface water bodies with nonlinear changes in water depth. Third, conventional soil column apparatuses can only simulate one type of effect on the vadose zone in rivers or lakes, and often neglect the gas-liquid two-phase flow. When the infiltration interface is not a free drainage boundary, the gas pressure in the soil will rise due to the continuous compression of gas, which will have a significant impact on soil infiltration. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides an experimental system for simulating the vadose zone water transport process under the influence of surface water bodies. This device not only meets the needs of various experiments using conventional soil column devices, but also allows for the investigation of changes in soil infiltration rate and cumulative infiltration volume under different surface water conditions, as well as the redistribution process of water under the influence of surface water bodies after infiltration, considering the gas-liquid two-phase interaction. This system can more accurately reflect the vadose zone water transport patterns under the influence of surface water bodies.

[0004] An experimental system for simulating the influence of surface water bodies on vadose zone moisture transport processes includes: a host computer module, a water supply unit, a flow collection unit, and, from top to bottom, an artificial rainfall unit, a surface water body simulation unit, a vadose zone simulation unit, and a groundwater control unit connected in sequence; wherein, the artificial rainfall unit, the surface water body simulation unit, and the groundwater control unit are all connected to the water supply unit; the artificial rainfall unit, the surface water body simulation unit, the vadose zone simulation unit, and the groundwater control unit are all electrically connected to the host computer module; the flow collection unit is connected to the surface water body simulation unit and the groundwater control unit;

[0005] The artificial rainfall unit is used to adjust the rainfall intensity and duration.

[0006] The surface water body simulation unit is used to simulate surface water bodies, which include rivers and lakes;

[0007] The vadose zone simulation unit is used to simulate different soil types;

[0008] The groundwater control unit is used to simulate groundwater;

[0009] The water supply unit is used to supply water to the artificial rainfall unit, the surface water body simulation unit, and the groundwater control unit.

[0010] The flow collection unit is used to collect the water overflowing from the surface water simulation unit and the underground control unit.

[0011] The host computer module is used to receive data from each unit, perform calculations, and display the data.

[0012] Furthermore, the artificial rainfall unit adopts a top-detachable airtight rainfall box; the top of the rainfall box is sealed to the main body of the rainfall box with a silicone gasket, which ensures the airtightness of the rainfall box and facilitates the replacement of industrial rubber-coated needles; the top of the rainfall box has a diversion structure, and the connection between the diversion structure and the main body of the rainfall box is sealed with a silicone gasket; the diversion structure makes the water pressure flowing into the rainfall box as uniform as possible, thereby ensuring the uniformity of rainfall; the water inlet of the diversion structure is connected to the water supply unit through a conduit; the conduit is equipped with a peristaltic pump, a switch, and a flow meter; a silicone pad is laid at the bottom of the rainfall box; multiple small holes are opened at the bottom of the rainfall box and corresponding to the silicone pad, and industrial rubber-coated needles simulating rainfall are installed in the small holes, which are protected by the silicone pad to ensure the airtightness of the industrial rubber-coated needles; the flow meter sends the collected data to the host computer module. In practical implementation, when the airtight rain box is sealed, the switch on the inlet conduit of the diversion structure is opened, and the water flow rate of the peristaltic pump is adjusted so that the water input into the rain box is greater than the water output through the industrial rubber nozzle. The rain box gradually fills with water, and the initiation of rainfall can be controlled by the switch of the peristaltic pump. Under atmospheric pressure, the switch of the peristaltic pump is turned off, and the rainfall stops. When the rain box is full of water, under water pressure, the simulated rainfall through the industrial rubber nozzle is equal to the flow rate of the peristaltic pump, which is obtained through a flow meter. The diversion structure at the top of the rain box ensures that the water pressure flowing into the rain box is as uniform as possible, thereby ensuring the uniformity of rainfall. By changing the diameter of the industrial rubber nozzle to change the size of the raindrops and adjusting the flow rate of the peristaltic pump, the amount of simulated rainfall can be controlled.

[0013] Furthermore, in simulating a river, the main body of the surface water simulation unit is an open sandbox, with the top of the sandbox sealed to the bottom of the rain box via a silicone gasket; the bottom of the sandbox is filled with sand according to the shape of the simulated river valley; a first water tank and a second water tank are fixedly installed on opposite sides of the outer wall of the sandbox to simulate the upstream and downstream of the river; multiple drainage holes are opened at the top of the connection between the sandbox and the first and second water tanks; the connection between the first and second water tanks and the sandbox is set as a groove; a first plexiglass baffle, a silicone plate, and a second plexiglass baffle are sequentially placed in the groove, that is, the order from the sandbox wall to the water tank wall is sand... The system comprises a tank wall, a first plexiglass baffle, a silicone plate, a second plexiglass baffle, and a water tank wall. The first and second plexiglass baffles are equipped with identical water outlet holes. The silicone plate has overflow holes designed to simulate a river. The inlet of the first water tank is connected to a water supply unit via a conduit equipped with a peristaltic pump, a switch, and a flow meter. The outlet of the first water tank is connected to a flow collection unit via a conduit. The inlet of the second water tank is also connected to the water supply unit via a conduit equipped with a peristaltic pump, a switch, and a flow meter. The outlet of the second water tank is connected to the flow collection unit via a conduit. In practice, coarse sand is filled at the bottom of the sand tank according to experimental requirements, followed by a layer of fine sand and silt to simulate the binary structure of a river valley. Multiple overflow holes are made on the silicone plate to simulate the shape of a river valley, with the hole depth matching the simulated river depth, simulating the lateral replenishment of the river. The peristaltic pump and switch control the water level in the first and second water tanks, simulating the upstream and downstream of a river. When the river depth remains constant, the difference between the flow meter readings connected to the inlets of the first and second water tanks and the flow meter readings connected to the corresponding outlets equals the lateral recharge of the river. If the influence of the river valley shape on the transport of moisture in the vadose zone is to be investigated, the perforated area on the silicone plate should be consistent with the shape of the valley.

[0014] Furthermore, in simulating a lake, the main body of the surface water simulation unit is an open sand box. The top of the sand box is sealed to the bottom of the rainfall box via a silicone gasket. The bottom of the sand box is filled with soil according to the size of the simulated lake, and the simulated lake is approximately ellipsoidal in shape. A pressure sensor is installed at the bottom of the lake. During heavy rainfall, the soil surface infiltration rate is initially controlled by the rainfall intensity, and then the infiltration capacity gradually weakens and is controlled by the soil's own infiltration capacity. At this time, a thin saturation layer will form on the soil surface, and overflow will occur on the surface. Part of the overflow will be discharged from the overflow hole, and part will flow into the lake to form water accumulation, which will exert pressure on the pressure sensor. The host computer module can transmit pressure according to the pressure. The data sent by the sensor determines the water depth of the simulated lake and calculates the water storage volume at that time, thereby calculating the infiltration rate and determining the real-time infiltration rate. A row of overflow holes is opened around the sand box at the same level as the surface of the landfill soil to realize the timely discharge of surface water, which is collected by the overflow collection unit, and the overflow flow rate is read by the flow meter. A third, fourth, fifth, and sixth water tanks are fixedly installed around the sand box to receive the water flowing out of the overflow holes. The outlets of the third, fourth, fifth, and sixth water tanks are all connected to the flow collection unit through conduits. Flow meters are installed on each conduit. The pressure sensor and flow meter send the collected data to the host computer module. In practice, the bottom of the sand box is filled with fine sand or silt to simulate the size of a lake, according to the experimental purpose. The water pressure at different lake depths is converted into lake depth by a pressure sensor installed at the bottom of the lake, and the infiltration rate is calculated. A row of overflow holes with a diameter of 5 mm is opened around the sand box at the same level as the surface of the backfill soil to allow the surface water to be discharged in time and collected by the overflow collection unit. The overflow flow rate is read by a flow meter.

[0015] Furthermore, the vadose zone simulation unit consists of multiple stacked, detachable vadose zone simulation boxes connected by a detachable base plate. The detachable base plate has a locking structure, with its edges secured by nuts, and multiple permeable holes in its central portion. The boxes are filled with soil layers of different properties to simulate vadose moisture transport under various conditions, according to experimental requirements. The device's detachability allows for more convenient and quick changes to the soil properties of the vadose zone simulation area.

[0016] Furthermore, multiple rows of sensor mounting holes are provided around the perimeter of each chamber. These holes are used to install sensors, including but not limited to moisture sensors, matrix potential sensors, and temperature sensors, according to the experimental purpose. The sensors transmit the detected data to the host computer module in real time. The host computer displays the changing trends of soil moisture, matrix potential, and temperature information transmitted by each sensor over time. A pressure measurement hole is provided between two adjacent sensor holes in the same row. The pressure measurement hole is connected to a double U-shaped tube through a measuring tube. The double U-shaped tube contains a low-density liquid, such as kerosene. Changes in pressure are reflected by changes in hydraulic pressure difference.

[0017] Furthermore, the groundwater control unit is a groundwater tank. The inlet of the groundwater tank is connected to the water supply unit via a conduit, which is equipped with a peristaltic pump, a switch, and a flow meter. The outlet of the groundwater tank is connected to the flow collection unit via a conduit, which is also equipped with a switch and a flow meter. The flow meter sends the collected data to the host computer module, which can then calculate the amount of groundwater replenishment. The host computer can calculate the input and output water volume of each unit based on the data sent by all the flow meters. In specific implementation, opening the switch on the inlet conduit and closing the switch on the outlet conduit, and starting the peristaltic pump, will cause the water level in the groundwater tank to rise to the target groundwater level. Closing the switch on the inlet conduit and opening the switch on the outlet conduit will discharge the groundwater and store it in the flow collection unit.

[0018] Furthermore, the surface water simulation unit and the vadose zone simulation unit, as well as the vadose zone simulation unit and the groundwater control unit, are all connected by a detachable base plate; the detachable base plate has a locking structure, the edges of the detachable base plate are fixed by nuts, and the middle part of the detachable base plate is provided with multiple water-permeable holes.

[0019] Beneficial effects

[0020] This invention proposes an experimental system for simulating the vadose zone water transport process under the influence of surface water bodies, which has the following advantages:

[0021] (1) A portable artificial rainmaking device that can precisely control rainfall intensity, rainfall duration, and real-time control of rainfall initiation can meet the needs of various indoor experimental rainfall conditions;

[0022] (2) Convenience Consideration of the vadose zone water transport and redistribution process under the influence of lateral river recharge, valley shape changes and lake water storage, the influence of lake water storage bottom area changes on infiltration process, and the influence of gas-liquid two-phase on water redistribution process, so as to more accurately reflect the vadose zone water transport pattern under the influence of surface water.

[0023] (3) The detachable soil column device can also conveniently change the lithology of the vadose zone simulation layer to meet a variety of experimental needs. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a front view of the experimental system for simulating the vadose zone water transport process under the influence of surface water bodies, provided in an embodiment of the present invention.

[0026] Figure 2 This is a front view of the sandbox device for simulating a lake provided in an embodiment of the present invention;

[0027] Figure 3 This is a top view of the sandbox with the maximum water storage capacity in a simulated lake, as provided in the embodiments of the present invention.

[0028] Figure 4 This is a schematic diagram of the plexiglass baffle provided in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the valley shape provided in an embodiment of the present invention;

[0030] Figure 6 It is a detachable base plate provided in the embodiments of the present invention;

[0031] Figure 7 This is the infiltration curve provided in the embodiments of the present invention;

[0032] Figure 8 This is a curve showing the change of water content at different depths of the vadose zone over time during a simulated lake operation, provided in an embodiment of the present invention.

[0033] Figure Descriptions: 1-Artificial Rainfall Unit; 2-Sand Box; 3, 4-Box of Vacuum Zone Simulation Unit; 5-Groundwater Tank of Groundwater Control Unit; 6, 30-Water Supply Tank; 7, 23, 28, 33-Peristaltic Pump; 8, 24, 25, 27, 34, 35, 38-Switch; 9-Rainfall Box; 10-Industrial Adhesive Needle; 11-First Water Tank; 12-Second Water Tank; 13-Silicone Pad; 14-First Acrylic Glass Baffle; 15-Water Outlet; 16-Silicone Plate; 17-Gas Pressure Measurement Hole; 18-Pressure Measuring Tube; 19-Double U-shaped Tube; 20-Removable Base Plate; 21-Pressure sensor; 22-Host computer module; 26, 29, 36, 52-Flow collection box; 31-Sensor mounting hole; 32-Sensor; 37-Water permeable hole; 39-Flow diversion structure; 40-Lake; 41-Saturation zone; 42-Lake surface; 43-Lake bottom; 44, 45, 46, 47, 48, 49, 50, 51-Flow meter; 53-Overflow hole; 54-Conduit; 55-Third water tank; 56-Fourth water tank; 57-Fifth water tank; 58-Sixth water tank; 59-Nut; 60-Outlet; 61-Second plexiglass baffle. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] In this invention, the use of terms such as "first," "second," etc., is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0038] like Figure 1 As shown, this invention provides an experimental system for simulating the vadose zone moisture transport process under the influence of surface water bodies. The system includes: a host computer module 22, a water supply unit, a flow collection unit, and, from top to bottom, an artificial rainfall unit 1, a surface water body simulation unit, a vadose zone simulation unit, and a groundwater control unit connected in sequence. The artificial rainfall unit 1, the surface water body simulation unit, and the groundwater control unit are all connected to the water supply unit; the artificial rainfall unit 1, the surface water body simulation unit, the vadose zone simulation unit, and the groundwater control unit are all connected to the host computer module 22; and the flow collection unit is connected to the surface water body simulation unit and the groundwater control unit.

[0039] The artificial rain unit 1 is used to adjust the rainfall intensity and duration. Specifically, the artificial rain unit adopts a top-detachable airtight rain box 9. The size and material of the rain box 9 can be adjusted according to actual needs and are not limited. In this application, the rain box is an acrylic glass box with a length of 425mm, a width of 425mm, and a height of 120mm. The top of the rain box 9 has a diversion structure 39, and a silicone gasket is provided at the connection between the diversion structure 39 and the main body of the rain box to ensure the airtightness of the rain box while facilitating the replacement of the industrial adhesive needle 10. The water inlet of the diversion structure is connected to the water supply tank 6 of the water supply unit through a conduit 54. The conduit is provided with a peristaltic... The device includes a pump 7, a switch 8, and a flow meter 44. A silicone pad 13 is laid at the bottom of the rainfall box. The thickness and hardness of the silicone pad can be adjusted according to experimental requirements and are not limited. In this application, the silicone pad has a thickness of 2mm and a hardness of 5. The bottom of the rainfall box and the silicone pad have multiple small holes corresponding to each other. Industrial adhesive needles 10 for simulating rainfall are installed on the small holes. The number and diameter of the small holes can be adjusted according to specific experimental requirements and are not limited. In this application, there are 400 small holes with a diameter of 4mm. The flow meter 44 sends the collected data to the host computer module 22.

[0040] The surface water body simulation unit is used to simulate surface water bodies, which include rivers and lakes.

[0041] Specifically, in combination Figure 1 , 4As shown in Figure 5, when simulating a river, the main body of the surface water simulation unit is an uncovered sand box 2. The size and material of the sand box can be adjusted according to experimental needs. In this application, the sand box is an plexiglass box with a length of 400mm, a width of 400mm, and a height of 300mm. The top of the sand box is sealed to the bottom of the rain box through a silicone gasket. The bottom of the sand box is filled with sand according to the shape of the simulated river valley. Figure 5 The sand box has a first water tank 11 and a second water tank 12 fixedly installed on opposite outer walls to simulate the upstream and downstream of a river. Multiple drainage holes 15 are opened at the top of the connection points between the first water tank 11, the second water tank 12, and the sand box 2. The diameter of the drainage holes can be adjusted according to actual needs and is not limited; in this application, the diameter of the drainage holes is 5mm. A groove is provided at the connection points between the first water tank 11, the second water tank 12, and the sand box 2. A first plexiglass baffle 14, a silicone plate 16, and a second plexiglass baffle are sequentially placed within the groove. Figure 4 As shown, the sequence from the sand tank wall to the water tank wall is: sand tank wall, first plexiglass baffle, silicone plate, second plexiglass baffle, and water tank wall. The hardness and thickness of the plexiglass baffle and silicone plate can be adjusted according to actual needs and are not limited. In this application, the silicone plate has a hardness of 5 and a thickness of 2mm. The first plexiglass baffle 14 and the second plexiglass baffle 61 are respectively provided with the same water outlet holes. The silicone plate 16 has overflow holes according to the experimental requirements of simulating a river. The diameter of the overflow holes can be adjusted according to experimental requirements. In this application, the diameter of the overflow holes is set to 5mm. The setting of 5mm overflow holes ensures that there are enough holes, which is convenient for adjustment when changing the shape of the river valley. If the holes are too large, it will be inconvenient for the silicone plate. The permeable area coincides with the river valley area; if the aperture of the hole is too small, water may accumulate at the orifice, affecting the water flow velocity; the inlet of the first water tank is connected to the water supply tank 6 of the water supply unit through a conduit, and the conduit is equipped with a peristaltic pump 23, a switch 24, and a flow meter 45; the outlet of the first water tank is connected to the flow collection box 26 of the flow collection unit through a conduit; the inlet of the second water tank is connected to the water supply tank 30 of the water supply unit through a conduit, and the conduit is equipped with a peristaltic pump 28, a switch 27, and a flow meter 46; the outlet of the second water tank is connected to the flow collection box 29 of the flow collection unit through a conduit; the silicone plate 16 is perforated according to the experimental requirements of simulating a river; the flow meter sends the collected data to the host computer module 22.

[0042] When simulating lakes, combine Figure 1 , Figure 2 , Figure 3As shown, the main body of the surface water simulation unit is an uncovered sand box 2. The top of the sand box is sealed to the bottom of the rain box through a silicone gasket. The bottom of the sand box is filled with soil according to the size of the simulated lake, and a pressure sensor 21 is installed at the bottom 43 of the lake. The host computer module 22 can determine the water depth of the simulated lake based on the data sent by the pressure sensor 21, calculate the water storage volume at this time, and thus calculate the infiltration rate to determine the real-time infiltration rate. A row of overflow holes 53 is opened around the sand box at the same level as the surface of the landfill soil. The diameter of the overflow holes is... The size can be adjusted according to specific experimental needs and is not limited thereto. The diameter of the overflow hole described in this application is 5mm. A third water tank 55, a fourth water tank 56, a fifth water tank 57, and a sixth water tank 58 are fixedly arranged around the sand box to receive the water flowing out of the overflow hole. The outlets 60 of the third, fourth, fifth, and sixth water tanks are all connected to the flow collection unit through conduits. A flow meter is installed on each conduit. The pressure sensor 21 and the flow meter send the collected data to the host computer module 22.

[0043] In practice, the sandboxes used to simulate lakes and rivers are replaceable because the entire soil column device is detachable, allowing for the replacement of different sandboxes when simulating different surface water bodies.

[0044] The vadose zone simulation unit is used to simulate different soil types.

[0045] Specifically, the vadose zone simulation unit consists of multiple stacked detachable simulated vadose zone boxes. The number of boxes can be adjusted according to experimental needs; in this application, there are two boxes connected by a detachable base plate. The detachable base plate has a locking structure, with its edges secured by nuts. The middle portion of the detachable base plate has multiple water-permeable holes, such as... Figure 6 As shown, the chamber is filled with soil layers of different properties to simulate the vadose and moisture transport under different conditions according to experimental requirements. Multiple rows of sensor mounting holes 31 are opened around the perimeter of each vadose zone simulation chamber. These sensor mounting holes are used to install sensors 32 to monitor soil information according to the experimental purpose, including but not limited to moisture sensors, matrix potential sensors, and temperature sensors. The sensors transmit the detected data to the host computer module 22 in real time. A pressure measurement hole 17 is opened between two adjacent sensor holes in the same row. The pressure measurement hole 17 is connected to a double U-shaped tube 19 through a measuring tube 18. The double U-shaped tube 19 contains a low-density liquid, such as kerosene, and changes in pressure are reflected by changes in hydraulic pressure difference.

[0046] The groundwater control unit is used to simulate groundwater.

[0047] Specifically, the groundwater control unit comprises multiple groundwater tanks. The inlet of each groundwater tank is connected to the water supply tank 6 of the water supply unit via a conduit. The conduit is equipped with a peristaltic pump 33, a switch 34, and a flow meter 49. The outlet of each groundwater tank is connected to the flow collection unit's flow meter box 36 via a conduit. The conduit is equipped with a switch 35 and a flow meter 50. Each flow meter sends the collected data to the host computer module 22.

[0048] The water supply unit is used to supply water to the artificial rainfall unit, the surface water simulation unit, and the groundwater control unit; specifically, the water supply unit consists of multiple water supply tanks.

[0049] The flow collection unit is used to collect the water overflowing from the surface water simulation unit and the groundwater control unit. Specifically, the flow collection unit consists of multiple flow collection boxes.

[0050] Combination Figure 1 and Figure 6 The surface water simulation unit and the vadose zone simulation unit, as well as the vadose zone simulation unit and the groundwater control unit, are all connected by a detachable base plate 20; for example Figure 6 As shown, the detachable base plate 20 has a locking structure, and the edges of the detachable base plate are fixed by nuts 59. The middle part of the detachable base plate is provided with multiple water-permeable holes 37. The number and diameter of the water-permeable holes can be adjusted according to experimental needs and are not limited thereto. In this application, 400 water-permeable holes with a diameter of 5mm are installed in the middle part of the detachable base plate.

[0051] The host computer module 22 is used to receive data from each unit for display and calculation processing.

[0052] Specifically, the host computer module 22 displays the changing trend of soil moisture, matrix potential, temperature and other information sent by the sensors set in the vadose zone simulation unit over time; it counts the water input and output of each unit based on the data sent by all flow meters; it determines the water depth of the simulated lake based on the data sent by the pressure sensor 21, calculates the corresponding water storage, and thus calculates the infiltration rate and determines the real-time infiltration rate.

[0053] Example 1

[0054] This embodiment uses a simulation experiment of moisture transport in the vadose zone under rainfall and lake conditions as an example to illustrate the specific operation method of the system:

[0055] A certain depth of silt and fine sand is filled into the main body of the sandbox. A certain volume of soil is then removed using a fishtail shovel, forming an ellipsoidal shape to simulate the function of a surface lake. When the rainfall intensity exceeds the soil's infiltration capacity, the surface soil becomes saturated (saturation zone 41). Simultaneously, water accumulates in the lake, increasing its depth. At its maximum depth, the lake's surface area is 42, and the area of ​​the lake bottom in contact with the soil is 43. The specific process is as follows:

[0056] S1: Turn off all switches on the system, fill both boxes of the vadose zone simulation unit with sandy loam, install moisture sensors in the sensor mounting holes, and make the groundwater control unit contact the box 4 of the vadose zone simulation unit. The switch 34 at the inlet of the groundwater tank and the switch 35 at the outlet of the groundwater tank are closed throughout the process.

[0057] S2: Fill the bottom of the sand box in the surface water simulation unit with silt, then cover it with fine sand to simulate lake sediments. Use a fishtail shovel to remove a certain volume of soil in an ellipsoidal shape to simulate the function of a surface lake. The size of the lake (40) is set according to the experimental purpose, and the lake satisfies the ellipsoidal equation: Where a, b, and c are the major and minor semi-axes of the 42 ellipse on the lake surface, and the maximum depth of the lake, respectively; x, y, and z correspond to the spatial positions of each point on the lake surface.

[0058] S3: Open switch 8 on the inlet pipe of the diversion structure in the artificial rainfall unit, and adjust the peristaltic pump 7 to the required rainfall intensity; the rainfall intensity is equal to the peristaltic pump flow rate / the surface area A of the sand box, and the rainfall intensity is represented by I; under the action of the diversion structure, the rainfall in the rainfall box 1 is more uniform; the flow meter 44 records the rainfall input W1 in real time and transmits it to the host computer module 22 (i.e., computer); if there is an overflow, the flow meter 51 records the overflow W2 in real time and transmits it to the host computer module 22;

[0059] S4: During the experiment, when the rainfall intensity was low, the water transport pattern was directly displayed by the water sensor reading, and the infiltration rate was equal to the rainfall intensity. When the rainfall intensity was high, the soil infiltration rate was greater than the rainfall intensity in the initial stage of infiltration, and infiltration proceeded according to the soil infiltration rate. As infiltration continued, the infiltration rate gradually decreased and eventually stabilized at the minimum infiltration rate. At the same time, because the rainfall was greater than the infiltration, the water accumulated in the lake, the lake level gradually rose, the water pressure increased, and the infiltration rate in the waterlogged area was greater than that in the non-waterlogged area. The reading of the water pressure sensor 21 gradually increased and transmitted the reading to the host computer module 22. The computer converted the corresponding water pressure into water depth h. When the water depth was h, the approximate equation of the ellipsoid was: The lake's water storage capacity W3 is approximately 2.09a1b1h, and the lake's bottom area S is: The bottom area of ​​the lake's water accumulation zone corresponding to water depth h Where p is a constant, with an approximate value of 1.6075; a1, b1, and c1 refer to the corresponding values ​​of the major semi-axis a, minor semi-axis b, and maximum depth c of the lake surface ellipse when the water depth is h, respectively.

[0060] S5: Based on the principle of water balance, the real-time infiltration rate is: Where: i is the infiltration rate, and s is the soil surface area, which is equal to the top surface area of ​​the soil column device minus the maximum surface area of ​​the lake (i.e., πab) + the bottom area of ​​the lake. max t represents time; the infiltration curve is as follows: Figure 8 As shown;

[0061] S6: After the rainfall ends, due to the water storage capacity of the lake, the water in the lake will diffuse in all directions, with a diffusion rate i. c It is related to the water depth and is a function of h. The infiltration rate per unit time is: I = S1i c S1 refers to the lake floor area at a water depth of h. The lake floor area varies with the lake depth, allowing us to obtain the cumulative infiltration curve of the soil throughout the entire rainfall process and after the rainfall ends, such as... Figure 7 .

[0062] S7: Moisture infiltration in the vadose zone simulation unit includes both saturation infiltration and redistribution. After rainfall begins, moisture temperature and matrix potential sensors are installed in the moisture sensor to record changes in water potential and matrix potential at different depths during moisture transport. Simultaneously, the air pressure measured in the double U-tube 19 is recorded over time. This yields the rainfall intensity, the water transport patterns under lake conditions, and the air pressure changes in the pores. The host computer module displays the moisture changes over time as follows: Figure 8 As shown.

[0063] S8: Adjust the flow rate of peristaltic pump 7 to change the rainfall intensity and lake surface area, while keeping the depth constant, and repeat the above experimental process; simulate the vadose zone water transport process under rainfall and lake conditions to obtain its transport law, such as... Figure 8 As shown.

[0064] Example 2

[0065] This embodiment uses the simulation of the influence of rivers of different shapes on the transport of water in the vadose zone or the lateral replenishment effect of rivers on the vadose zone as examples to illustrate the specific operation method of the system:

[0066] S1: Fill the bottom of the sand box device 2 with coarse sand, and then cover the upper layer with fine sand and silt to simulate the binary structure of the valley. The valley filling shape is set as "U". Make multiple 5mm overflow holes in the silicone plate sandwiched between the plexiglass baffle and the valley shape. Apply a thin layer of Vaseline to the edges of the silicone plate and the wooden board to make them stick together.

[0067] S2: Turn on switches 24 and 27 to create stable upstream and downstream water levels using peristaltic pumps 23 and 28;

[0068] S3: Turn on switch 8 and adjust peristaltic pump 7 to achieve the desired rainfall intensity;

[0069] S4: Use the host computer module 22 to record the changes in sensor 32 readings over time, record the changes in water potential and matrix potential at different depths as water migrates, and simultaneously record the changes in air pressure measured in the double U-tube 19 over time.

[0070] S5: Adjust the flow rate of peristaltic pump 7 to change the rainfall intensity and river shape, and repeat the above experimental process.

[0071] The above steps can be used to simulate the vadose zone water transport process under certain "U"-shaped river conditions and different rainfall intensities. If the entire sand box simulates the vadose zone, and the first and second water tanks simulate the upstream and downstream of the river, the lateral replenishment effect of the river on the vadose zone can be explored.

[0072] In addition to the above embodiments, this device can also be used to investigate the transport patterns of moisture and solutes in the vadose zone under the interaction of surface water, soil water, and groundwater. Furthermore, leveraging the advantages of the artificial rainfall unit of this invention, it can investigate the potential impact of parameters such as rainfall intensity and duration on the infiltration process and moisture transport in the vadose zone. The device's detachability allows for the investigation of vadose zone soil properties and moisture transport patterns under different surface water bodies, rainfall conditions, and groundwater conditions, and facilitates convenient replacement of experimental soil layers. Simultaneously, utilizing the perimeter of the sensor mounting holes, combined with the device's ability to simulate diverse surface water bodies, it can investigate the spatial differences in moisture diffusion in unevenly distributed soil layers, and so on.

[0073] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0074] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An experimental system for simulating the vadose zone moisture transport process under the influence of surface water bodies, characterized in that, include: The system comprises a host computer module, a water supply unit, a flow collection unit, and, from top to bottom, an artificial rainfall unit, a surface water simulation unit, a vadose zone simulation unit, and a groundwater control unit, all connected sequentially. The artificial rainfall unit, surface water simulation unit, and groundwater control unit are all connected to the water supply unit. The artificial rainfall unit, surface water simulation unit, vadose zone simulation unit, and groundwater control unit are all connected to the host computer module. The flow collection unit is connected to the surface water simulation unit and the groundwater control unit. The artificial rainfall unit is used to adjust the rainfall intensity and duration. The vadose zone simulation unit is used to simulate different soil types; The vadose zone simulation unit consists of multiple stacked detachable simulated vadose zone boxes. Each box has multiple rows of sensor mounting holes around its perimeter. These holes are used to install sensors according to the experimental purpose. The sensors transmit the detected data to the host computer module in real time. A pressure measurement hole is provided between two adjacent sensor holes in the same row. The pressure measurement hole is connected to a double U-shaped tube through a measuring tube. The groundwater control unit is used to simulate groundwater; The water supply unit is used to supply water to the artificial rainfall unit, the surface water body simulation unit, and the groundwater control unit. The flow collection unit is used to collect the water overflowing from the surface water simulation unit and the groundwater control unit. The host computer module is used to receive data from each unit, perform calculations, and display the data. The surface water body simulation unit is used to simulate surface water bodies, which include rivers and lakes; In simulating a river, the main body of the surface water simulation unit is an open sandbox. The top of the sandbox is sealed to the bottom of the rain box via a silicone gasket. A first water tank and a second water tank are fixedly installed on opposite sides of the outer wall of the sandbox. Multiple drainage holes are opened at the top of the connections between the first and second water tanks and the sandbox. Grooves are provided at the connections between the first and second water tanks and the sandbox. A first acrylic glass baffle, a silicone plate, and a second acrylic glass baffle are sequentially placed within the grooves. The first acrylic glass baffle and the second acrylic glass baffle... The glass baffles are equipped with identical water outlets; the silicone plate has holes cut according to the experimental requirements of simulating a river; the inlet of the first water tank is connected to the water supply unit via a conduit, which is equipped with a peristaltic pump, a switch, and a flow meter; the outlet of the first water tank is connected to the flow collection unit via a conduit; the inlet of the second water tank is connected to the water supply unit via a conduit, which is equipped with a peristaltic pump, a switch, and a flow meter; the outlet of the second water tank is connected to the flow collection unit via a conduit; the flow meter sends the collected data to the host computer module; In simulating a lake, the main body of the surface water simulation unit is an open sand box. The top of the sand box is sealed to the bottom of the rain box via a silicone gasket. The bottom of the sand box is filled with soil according to the size of the simulated lake, and a pressure sensor is installed at the bottom of the lake. A row of overflow holes is opened around the sand box at the same level as the surface of the backfill soil. A third, fourth, fifth, and sixth water tank are fixedly installed around the sand box to receive the water flowing out of the overflow holes. The outlets of the third, fourth, fifth, and sixth water tanks are all connected to the flow collection unit through conduits. A flow meter is installed on each conduit. The pressure sensor and flow meter send the collected data to the host computer module.

2. The experimental system for simulating the influence of surface water bodies on vadose zone moisture transport processes according to claim 1, characterized in that, The artificial rainfall unit adopts an airtight rainfall box with a detachable top; the top of the rainfall box has a diversion structure; a silicone gasket is provided at the connection between the diversion structure and the main body of the rainfall box; the water inlet of the diversion structure is connected to the water supply unit through a conduit; a peristaltic pump, a switch, and a flow meter are provided on the conduit; a silicone pad is laid at the bottom of the rainfall box, and multiple small holes are opened at the bottom of the rainfall box and the silicone pad, with industrial adhesive needles for simulating rainfall installed on the small holes; the flow meter sends the collected data to the host computer module.

3. The experimental system for simulating the influence of surface water bodies on vadose zone moisture transport processes according to claim 1, characterized in that, The boxes are connected by a detachable bottom plate; the detachable bottom plate has a locking structure, the edges of the detachable bottom plate are fixed by nuts, and the middle part of the detachable bottom plate is provided with multiple water-permeable holes; The chamber is filled with soil layers of different properties according to experimental requirements to simulate the vadose and moisture transport under different conditions.

4. The experimental system for simulating the influence of surface water bodies on vadose zone moisture transport processes according to claim 1, characterized in that, The groundwater control unit is a groundwater tank. The inlet of the groundwater tank is connected to the water supply unit through a conduit. The conduit is equipped with a peristaltic pump, a switch, and a flow meter. The outlet of the groundwater tank is connected to a flow collection box through a conduit. The conduit is equipped with a switch and a flow meter. The flow meter sends the collected data to the host computer module.

5. The experimental system for simulating the influence of surface water bodies on vadose zone moisture transport processes according to claim 1, characterized in that, The surface water simulation unit and the vadose zone simulation unit, as well as the vadose zone simulation unit and the groundwater control unit, are all connected by a detachable base plate. The detachable base plate has a locking structure, and the edges of the detachable base plate are fixed by nuts. The middle part of the detachable base plate is provided with multiple water-permeable holes.

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