Experimental system for simulating aeration zone moisture migration process influenced by surface water body

Abstract

The invention discloses an experimental system for simulating an aeration zone moisture migration process influenced by a surface water body. The experimental system comprises an upper computer module, a water supply unit, a flow collection unit, and an artificial rainfall unit, a surface water body simulation unit, an aeration zone simulation unit and an underground water control unit which are sequentially connected from top to bottom, the upper computer module is used for receiving data of each unit; the artificial rainfall unit is used for adjusting rainfall intensity and rainfall duration; the surface water body simulation unit is used for simulating a surface water body; the aeration zone simulation unit is used for simulating different soil types; the groundwater control unit is used for simulating groundwater; the water supply unit is used for supplying water to the artificial rainfall unit, the surface water body simulation unit and the underground water control unit; and the flow collection unit is used for collecting water overflowing from the surface water body simulation unit and the underground water control unit. The system can accurately reflect the moisture migration rule of the aeration zone under the influence of a surface water body.

Description

Technical Field

[0001] The invention relates to the fields of hydrogeology and soil monitoring, and in particular to an experimental system for simulating a water migration process in a vadose zone affected by surface water. Background Art

[0002] The vadose zone refers to the unsaturated zone between the surface and the aquifer. It is a channel for material exchange and water transport between the surface and groundwater, and is a key link in the connection between the atmosphere, surface hydrosphere and groundwater. The water migration process in the vadose zone is affected by many factors, such as stratum lithology, topography, climate, surface water accumulation, etc. Exploring the distribution of water in the vadose zone over time and space and studying the mechanism of its water migration are of great significance for studying the conversion process of surface water and groundwater, achieving accurate evaluation of water resources, and predicting the scope of soil pollution. Using physical models to explore the laws of water migration in the vadose zone is an effective means of scientific research on the vadose zone. The soil column device has been widely used in the process of simulating the study of the vadose zone due to its simple preparation and convenient operation. However, conventional soil column devices also have certain limitations. First, conventional soil column devices are integrated structures, which are not convenient for replacing soil layers. When it is necessary to explore the properties of the air-filled zones of different soil layers, the experimental period will be extended and the cost of the experiment will be increased. Second, conventional soil column devices mostly use constant head surface water accumulation to simulate surface water accumulation, which is not suitable for simulating the water migration process in the air-filled zone of the surface water body influence area with nonlinear changes in water accumulation depth. Third, conventional soil column devices can only simulate one effect on the air-filled zone in rivers or lakes, and often ignore the effect of gas-liquid two-phase flow. When the infiltration lower interface is not a free drainage boundary, the air pressure in the soil will rise due to the continuous compression of the gas, which will have a great impact on the infiltration of the soil. Summary of the invention

[0003] In view of the above problems, the present invention provides an experimental system for simulating the water migration process in the vadose zone affected by surface water. The device can not only meet the needs of various experiments of conventional soil column devices, but also explore the changes in soil infiltration rate and cumulative infiltration volume when surface water changes dynamically under different surface water conditions, as well as the redistribution process of water under the action of surface water after the infiltration is completed, considering the effect of gas-liquid two-phase nature, so as to more accurately reflect the water migration law in the vadose zone under the influence of surface water.

[0004] An experimental system for simulating the water migration process of the vadose zone affected by surface water, comprising: a host computer module, a water supply unit, a flow collection unit, and an artificial rainfall unit, a surface water simulation unit, a vadose zone simulation unit, and a groundwater control unit connected in sequence from top to bottom; wherein the artificial rainfall unit, the surface water simulation unit, and the groundwater control unit are all connected to the water supply unit; the artificial rainfall unit, the surface water 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 simulation unit and the groundwater control unit;

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

[0006] The surface water simulation unit is used to simulate surface water, wherein the surface water includes 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 simulation unit, and the groundwater control unit;

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

[0011] The host computer module is used to receive data from each unit for calculation, processing and display.

[0012] Furthermore, the artificial rainfall unit adopts an airtight rainfall box with a detachable top; the top of the rainfall box is sealed and connected to the main body of the rainfall box by a silicone gasket, which can ensure the airtightness of the rainfall box while facilitating the replacement of industrial glue needles; the top of the rainfall box is a shunt structure, and the connection between the shunt structure and the main body of the rainfall box is sealed and connected by a silicone gasket; the shunt structure is used to make the water pressure flowing into the rainfall box as uniform as possible, thereby ensuring the uniformity of rainfall; the water inlet end of the shunt structure is connected to the water supply unit through a conduit; a peristaltic pump, a switch, and a flow meter are arranged on the conduit; a silicone pad is laid on the bottom of the rainfall box; a plurality of small holes are opened on the bottom of the rainfall box and the silicone pad correspondingly, and industrial glue needles simulating rainfall are installed on the small holes. Under the action of the silicone pad, the airtightness of the installation of the industrial glue needles is ensured; the flow meter sends the collected data to the upper computer module. In specific implementation, when the airtight rain box is sealed, the switch on the water inlet conduit of the diversion structure is turned on, and the water flow rate of the peristaltic pump is adjusted so that the amount of water input into the rain box is greater than the amount of water output through the industrial glue needle. The rain box is gradually filled with water, and the start of rainfall can be controlled by the switch of the peristaltic pump. Under the action of atmospheric pressure, the switch of the peristaltic pump is turned off and the rainfall stops. When the rain box is full of water, under the action of water pressure, the rainfall simulated by the industrial glue needle is equal to the flow rate of the peristaltic pump, and the flow rate is obtained through a flow meter. The diversion structure at the top of the rain box can make the water pressure flowing into the rain box as uniform as possible, thereby ensuring the uniformity of rainfall; by changing the diameter of the industrial glue needle to change the size of the raindrops, and adjusting the flow rate of the peristaltic pump, the size of the simulated rainfall can be controlled.

[0013] Furthermore, when simulating a river, the main body of the surface water simulation unit is an uncovered sand box, and the top of the sand box is sealed and connected to the bottom of the rainfall box through a silicone gasket; the bottom of the sand box is filled with sand and soil according to the shape of the simulated river valley; the first water tank and the second water tank are fixedly arranged on the outer walls on both sides of the opposite sides of the sand box, respectively, for simulating the upstream and downstream of the river; multiple drainage holes are opened on the top of the connection between the sand box and the first water tank and the second water tank; the connection between the first water tank, the second water tank and the sand box is configured as a groove; the first organic glass baffle, the silicone plate, and the second organic glass baffle are sequentially placed in the groove, that is, the order from the sand box wall to the water tank wall is sand. Box wall, first organic glass baffle, silicone plate, second organic glass baffle, water tank wall; wherein, the first organic glass baffle and the second organic glass baffle are provided with the same water outlet holes; the silicone plate is provided with overflow holes according to the experimental requirements of simulating rivers; the water inlet of the first water tank is connected to the water supply unit through a conduit, and the conduit is provided with a peristaltic pump, a switch, and a flow meter; the water outlet of the first water tank is connected to the flow collection unit through a conduit; the water inlet of the second water tank is connected to the water supply unit through a conduit, and the conduit is provided with a peristaltic pump, a switch, and a flow meter; the water outlet of the second water tank is connected to the flow collection unit through a conduit. In specific implementation, coarse sand is filled at the bottom of the sand box according to the experimental requirements, and then the upper layer is covered with fine sand and silt to simulate the binary structure of the river valley. According to the needs of simulating the river valley shape of the river, multiple overflow holes are opened on the silicone plate, and the opening depth is consistent with the simulated river depth to simulate the lateral recharge effect of the river. The water level height in the first water tank and the second water tank is controlled by the peristaltic pump and the switch to simulate the upstream and downstream of the river. When the river depth remains constant, the flow meter reading connected to the water inlets of the first water tank and the second water tank minus the flow meter reading connected to the corresponding water outlets is equal to the lateral recharge of the river; if the influence of the river valley shape on the migration of water in the vadose zone is to be investigated, the opening area on the silica gel plate can be consistent with the shape of the valley.

[0014] Furthermore, when simulating a lake, the main body of the surface water simulation unit is a sand box without a cover, and the top of the sand box is sealed and connected to the bottom of the rainfall box through a silicone gasket; the bottom of the sand box is filled with soil according to the size of the simulated lake, the shape of the simulated lake is approximately an ellipsoid, and a pressure sensor is installed at the bottom of the lake; when the rainfall is heavy, the infiltration rate of the soil surface is initially controlled by the rainfall intensity, and then the infiltration capacity gradually weakens and is controlled by the infiltration capacity of the soil itself. At this time, a thin saturated layer will be formed on the soil surface. At the same time, overflow will be formed on the surface, part of which will be discharged from the overflow hole, and part of which will flow into the lake to form accumulated water, which will exert pressure on the pressure sensor. The upper computer module can The data sent by the sensor determines the water depth of the simulated lake, calculates the water storage at this time, and thus the infiltration amount can be calculated to determine the real-time infiltration rate; a row of overflow holes are opened around the sand box at the same position as the landfill soil surface to achieve timely discharge of surface water, which is collected by the overflow collection unit, and the overflow volume is read by the flow meter; the third water tank, the fourth water tank, the fifth water tank, and the sixth water tank are fixedly arranged around the sand box to receive the water flowing out of the overflow hole; the water outlets of the third water tank, the fourth water tank, the fifth water tank, and the sixth water tank are connected to the flow collection unit through a conduit; a flow meter is arranged on the conduit; the pressure sensor and the flow meter send the collected data to the upper computer module. During the specific implementation, fine sand or silt is filled at the bottom of the sand box to simulate the size of the lake according to the experimental purpose. The water pressure at different lake water depths is converted into lake water depth through the pressure sensor installed at the bottom of the lake, and the infiltration rate at this time is calculated. A row of overflow holes with a diameter of 5 mm are opened around the sand box at the same level as the surface of the landfill soil to achieve timely discharge of surface water, which is collected by the overflow collection unit and the overflow volume is read by the flow meter.

[0015] Furthermore, the aeration zone simulation unit is composed of a plurality of detachable boxes simulating the aeration zone, which are stacked and connected by a detachable bottom plate; the detachable bottom plate is a locking structure, the edge of the detachable bottom plate is fixed by nuts, and the middle part of the detachable bottom plate is provided with a plurality of water-permeable holes; the box is filled with soil layers of different properties according to experimental requirements to simulate the migration of aerated water under different circumstances. The detachability of the device makes it easier and faster to change the soil properties of the aeration zone simulation area.

[0016] Furthermore, multiple rows of sensor installation holes are opened around each box body, and the sensor installation holes are used to install sensors according to the experimental purpose, including but not limited to moisture sensors, matrix potential sensors, and temperature sensors; the sensors send the detected data to the host computer module in real time, and the host computer displays the change trend of the moisture, matrix potential, and temperature information in the soil sent by each sensor over time; an air pressure measurement hole is opened between two adjacent sensor holes in the same row; the air pressure measurement hole is connected to the double U-shaped tube through a measuring tube, and the double U-shaped tube is filled with a low-density liquid, such as kerosene, and the change of air pressure is reflected by the change of hydraulic pressure difference.

[0017] Furthermore, the groundwater control unit is an underground water tank, the water inlet of the underground water tank is connected to the water supply unit through a conduit, and the conduit is provided with a peristaltic pump, a switch, and a flow meter; the water outlet of the underground water tank is connected to the flow collection unit through a conduit, and the conduit is provided with a switch and a flow meter; the flow meter sends the collected data to the upper computer module, and the groundwater recharge can be counted. The upper computer can count the amount of water input and output of each unit based on the data sent by all the flow meters. In specific implementation, turn on the switch on the conduit at the water inlet end, turn off the switch on the conduit at the water outlet end, turn on the peristaltic pump, and the water level in the underground water tank will rise to the target groundwater level; turn off the switch on the conduit at the water inlet end, and turn on the switch on the conduit at the water outlet end, so that the groundwater can be discharged and stored in the flow collection unit.

[0018] Furthermore, the surface water simulation unit and the vadose zone simulation unit, and the vadose zone simulation unit and the groundwater control unit are connected through a detachable bottom plate; the detachable bottom plate is a locking structure, the edge of the detachable bottom plate is fixed by nuts, and a plurality of water-permeable holes are provided in the middle part of the detachable bottom plate.

[0019] Beneficial Effects

[0020] The present invention proposes an experimental system for simulating the water migration process in the vadose zone affected by surface water, which has the following advantages:

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

[0022] (2) Convenience: Considering the migration and redistribution of water in the vadose zone under the influence of river lateral recharge, changes in river valley shape, and lake water storage, considering the impact of changes in lake water storage bottom area on the infiltration process, considering the impact of gas-liquid duality on the water redistribution process, and more accurately reflecting the law of water migration in the vadose zone under the influence of surface water;

[0023] (3) The detachable soil column device can also conveniently change the lithology of the simulated layer of the aeration zone to meet various experimental needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is a front view of an experimental system for simulating the water migration process in the vadose zone affected by surface water provided by an embodiment of the present invention;

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

[0027] Figure 3 It is a top view of a sand box with maximum water storage capacity in a lake when simulating a lake provided by an embodiment of the present invention;

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

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

[0030] Figure 6 is a detachable bottom plate provided by an embodiment of the present invention;

[0031] Figure 7 is an infiltration curve provided by an embodiment of the present invention;

[0032] Figure 8 It is a curve showing the change of water content at different depths in the vadose zone over time when simulating lake action provided by an embodiment of the present invention;

[0033] Description of the drawings: 1-artificial rainfall unit; 2-sand box; 3, 4-box of the air-encapsulating zone simulation unit; 5-underground water tank of the 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 glue needle; 11-first water tank; 12-second water tank; 13-silicone pad; 14-first organic glass baffle; 15-water outlet; 16-silicone plate; 17-air pressure measurement hole; 18-pressure measuring tube; 19-double U-shaped tube; 20-detachable bottom 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-diversion structure; 40-lake; 41-saturated 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-water outlet; 61-second plexiglass baffle. DETAILED DESCRIPTION

[0034] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0035] In the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0036] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] like Figure 1 As shown, the present invention provides an experimental system for simulating the water migration process of the vadose zone affected by the surface water body, the system comprising: an upper computer module 22, a water supply unit, a flow collection unit, and an artificial rainfall unit 1, a surface water body simulation unit, a vadose zone simulation unit, and a groundwater control unit which are sequentially connected from top to bottom; wherein 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 upper computer module 22; the flow collection unit is connected to the surface water body simulation unit and the groundwater control unit;

[0039] The artificial rainfall unit 1 is used to adjust the rainfall intensity and duration. Specifically, the artificial rainfall unit adopts an airtight rainfall box 9 with a detachable top. The size and material of the rainfall box 9 are adjusted according to actual needs and are not limited. The rainfall box described in this application is a plexiglass box with a length of 425mm, a width of 425mm, and a height of 120mm; the top of the rainfall box 9 is a diversion structure 39, and a silicone gasket is provided at the connection between the diversion structure 39 and the main body of the rainfall box, which ensures the airtightness of the rainfall box while facilitating the replacement of the industrial glue needle 10; the water inlet end of the diversion structure is connected to the water supply tank 6 of the water supply unit through a conduit 54, and a creeping gasket is provided on the conduit. A dynamic pump 7, a switch 8, and a flow meter 44; a silicone pad 13 is laid on the bottom of the rainfall box. The thickness and hardness of the silicone pad can be adjusted according to the experimental requirements and are not limited. The thickness of the silicone pad described in this application is 2 mm and the hardness is 5; a plurality of small holes are correspondingly opened on the bottom of the rainfall box and the silicone pad, and an industrial glue needle 10 for simulating rainfall is installed on the small holes. The number of small holes and the diameter of the small holes can be adjusted according to the specific experimental scene requirements and are not limited. In this application, the number of small holes is 400 and the diameter is 4 mm; the flow meter 44 sends the collected data to the host computer module 22.

[0040] The surface water simulation unit is used to simulate surface water, wherein the surface water includes rivers and lakes.

[0041] Specifically, combined Figure 1 , 4As shown in , 5, when simulating a river, 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 the experimental requirements. The sand box in this application is a plexiglass box with a length of 400mm, a width of 400mm, and a height of 300mm; the top of the sand box is sealed and connected to the bottom of the rainfall box through a silicone gasket; the bottom of the sand box is filled with sand and soil according to the shape of the river valley of the simulated river, such as Figure 5 ; The first water tank 11 and the second water tank 12 are fixedly arranged on the outer walls of the opposite sides of the sand box, which are used to simulate the upstream and downstream of the river; the top of the connection between the first water tank 11, the second water tank 12 and the sand box 2 is provided with multiple drainage holes 15, and the diameter of the drainage holes can be adjusted according to actual needs and is not limited. The diameter of the drainage holes described in this application is 5mm; the connection between the first water tank 11, the second water tank 12 and the sand box 2 is provided with a groove shape; the first organic glass baffle 14, the silicone plate 16, and the second organic glass baffle are sequentially placed in the groove, such as Figure 4 As shown, the order from the sand box wall to the water tank wall is the sand box wall, the first organic glass baffle, the silicone plate, the second organic glass baffle, and the water tank wall. The hardness and thickness of the organic glass baffle and the silicone plate can be adjusted according to actual needs and are not limited thereto. The silicone plate described in this application has a hardness of 5 and a thickness of 2 mm; wherein the first organic glass baffle 14 and the second organic glass baffle 61 are correspondingly provided with the same water outlet holes; the silicone plate 16 is provided with overflow holes according to the experimental needs of simulating a river, and the diameter of the overflow holes can be adjusted according to the experimental needs. The diameter of the overflow holes described in this application is set to 5 mm. The setting of the 5 mm overflow holes can make the number of holes sufficient, which is convenient for adjustment when changing the shape of the river valley. If the holes are too large, it is inconvenient for the silicone plate The permeable area is consistent with the river valley area; if the aperture of the hole is too small, water may accumulate at the hole mouth, affecting the water flow rate; the water inlet of the first water tank is connected to the water supply tank 6 of the water supply unit through a conduit, and a peristaltic pump 23, a switch 24, and a flow meter 45 are provided on the conduit; the water outlet of the first water tank is connected to the flow collection box 26 of the flow collection unit through a conduit; the water inlet of the second water tank is connected to the water supply tank 30 of the water supply unit through a conduit, and a peristaltic pump 28, a switch 27, and a flow meter 46 are provided on the conduit; the water outlet of the second water tank is connected to the flow collection box 29 of the flow collection unit through a conduit; the silica gel plate 16 is opened 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, combining Figure 1 , Figure 2 , Figure 3As shown, the main body of the surface water simulation unit is an uncovered sand box 2, and the top of the sand box is sealed and connected to the bottom of the rainfall 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 of the lake 43. The upper computer module 22 can determine the water depth of the simulated lake according to the data sent by the pressure sensor 21, calculate the water storage at this time, and thus calculate the infiltration amount to determine the real-time infiltration rate; a row of overflow holes 53 are opened around the sand box at the same level as the landfill soil surface, and the diameter of the overflow hole is The size can be adjusted according to specific experimental needs and is not limited. The diameter of the overflow hole in this application is 5 mm; 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 water outlets 60 of the third water tank, the fourth water tank, the fifth water tank, and the sixth water tank are connected to the flow collection unit through a conduit; a flow meter is arranged on the conduit; the pressure sensor 21 and the flow meter send the collected data to the upper computer module 22.

[0043] In specific implementation, the corresponding sand boxes when simulating lakes and rivers are replaceable because the entire soil column device is detachable, and different corresponding sand boxes are replaced when simulating different surface water bodies.

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

[0045] Specifically, the aeration zone simulation unit is composed of a plurality of detachable boxes simulating the aeration zone stacked together. The number of boxes can be adjusted according to the experimental requirements. The number of boxes in the present application is 2, and the boxes are connected by a detachable bottom plate; the detachable bottom plate is a locking structure, the edge of the detachable bottom plate is fixed by nuts, and the middle part of the detachable bottom plate is provided with a plurality of water permeable holes, such as Figure 6 As shown; the box is filled with soil layers of different properties according to the experimental requirements to simulate the migration of air-entrained water under different circumstances. Multiple rows of sensor installation holes 31 are opened around each air-entrained zone simulation box, and the sensor installation holes are used to install sensors 32 to monitor soil information according to the purpose of the experiment, including but not limited to moisture sensors, matrix potential sensors, and temperature sensors; the sensors send the detected data to the host computer module 22 in real time; an air pressure measurement hole 17 is opened between two adjacent sensor holes in the same row; the air pressure measurement hole 17 is connected to the double U-shaped tube 19 through a measuring tube 18, and the double U-shaped tube 19 is filled with low-density liquid, such as kerosene, and the change of air pressure is reflected by the change of hydraulic pressure difference.

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

[0047] Specifically, the groundwater control unit is a plurality of underground water tanks, the water inlet of the underground water tank is connected to the water supply tank 6 of the water supply unit through a conduit, and a peristaltic pump 33, a switch 34, and a flow meter 49 are provided on the conduit; the water outlet of the underground water tank body is connected to the flow mobile phone box 36 of the flow collection unit through a conduit, and a switch 35 and a flow meter 50 are provided on the conduit; each flow meter sends the collected data to the upper 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 is a plurality of water supply tanks.

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

[0050] Combination Figure 1 and Figure 6 The surface water simulation unit and the vadose zone simulation unit, and the vadose zone simulation unit and the groundwater control unit are connected via a detachable bottom plate 20; Figure 6 As shown, the removable bottom plate 20 is a locking structure, the edge of the removable bottom plate is fixed by a nut 59, and a plurality of water holes 37 are provided in the middle part of the removable bottom plate. The number and diameter of the water holes can be adjusted according to the experimental requirements and are not limited thereto. In the present application, 400 water holes with a diameter of 5 mm are installed in the middle part of the removable bottom plate.

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

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

[0053] Example 1

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

[0055] The sand box body is filled with a certain depth of silt and fine sand, and a certain volume of soil is excavated with a fishtail shovel. The shape is ellipsoidal, simulating the effect of surface lakes. When the rainfall intensity is greater than the soil infiltration capacity, the soil surface is saturated, that is, saturated zone 41. At the same time, the accumulated water will gather in the lake, and the lake depth will increase. When the maximum water depth is reached, the surface area of ​​the lake is 42. At this time, the area of ​​the lake bottom in contact with the soil is the lake bottom area 43. The specific process is:

[0056] S1: Turn off all switches on the system, fill the two boxes of the vadose zone simulation unit with sandy loam, install a moisture sensor in the sensor installation hole, make the groundwater control unit contact the box 4 of the vadose zone simulation unit, and fully close the switch 34 of the underground water tank inlet and the switch 35 of the underground water tank outlet;

[0057] S2: The bottom of the sand box of the surface water simulation unit is filled with silt, and then the upper layer is covered with fine sand to simulate lake sediments. A certain volume of soil is excavated with a fishtail shovel. The shape is an ellipsoid to simulate the effect of a surface lake. The size of the lake 40 is set according to the experimental purpose. The lake satisfies the ellipsoid equation: Where a, b, and c are the major and minor semi-axes of the 42-dimensional ellipse on the lake surface, and the maximum depth of the lake; x, y, and z correspond to the spatial positions of each point on the lake surface;

[0058] S3: Turn on the switch 8 on the water inlet conduit 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 upper surface area A of the sand box, and the rainfall intensity is represented by I; the diversion structure makes the rainfall box 1 more uniform; the flow meter 44 records the rainfall input W in real time 1 And transmit it to the host computer module 22 (ie, computer); if there is overflow, the flow meter 51 records the overflow volume W in real time 2 And transmit to the host computer module 22;

[0059] S4: During the experiment, when the rainfall intensity is small, the law of water migration is directly displayed by the water sensor reading, and the infiltration rate is equal to the rainfall intensity; when the rainfall intensity is large, the soil infiltration rate is greater than the rainfall intensity at the initial stage of infiltration, and infiltration is carried out according to the soil infiltration rate; as the infiltration proceeds, the infiltration rate gradually decreases and finally stabilizes to the minimum infiltration rate. At the same time, because the rainfall is greater than the infiltration, the accumulated water gathers in the lake, the lake water level gradually rises, the water pressure increases, and the infiltration rate in the water accumulation area will be greater than that in the non-water accumulation area; the water pressure sensor 21 reading gradually increases and transmits the reading to the host computer module 22, and the computer converts the corresponding water pressure into the water depth h; when the water depth is h, the satisfied ellipsoid equation is approximately: Lake water storage volume W 3 Approximately: 2.09a 1 b 1h, the lake bottom area S is: The bottom area of ​​the lake corresponding to the water depth h Among them, p is a constant, the approximate value is 1.6075; a 1 、b 1 、c 1 They respectively refer to the corresponding values ​​of the major semiaxis a, minor semiaxis b of the lake surface ellipse and the maximum depth c of the lake when the water depth is h.

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

[0061] S6: After the rainfall ends, due to the water storage function of the lake, the water in the lake will diffuse to the surroundings, and the diffusion rate is i c It is related to the depth of water and is a function of h. At this time, the infiltration rate per unit time is: I = S 1 i c , S 1 Refers to the bottom area of ​​lake water when the water depth is h. The bottom area of ​​lake water changes with the depth of the lake, and the cumulative infiltration curve of the soil during the entire rainfall process and after the rainfall can be obtained, such as Figure 7 .

[0062] S7: The infiltration of water in the vadose zone simulation unit includes the saturated infiltration process and the water redistribution process. After the rainfall begins, the water temperature and matrix potential sensors are installed in the water sensor to record the changes of water potential and matrix potential at different depths with the water migration process, and at the same time record the changes of air pressure measured in the double U-shaped tube 19 with time. The rainfall intensity and the water migration law under the action of the lake and the law of air pressure change in the pores are obtained; the upper computer module shows the changes of water with time as follows Figure 8 shown.

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

[0064] Example 2

[0065] This embodiment uses the simulation of the influence of rivers of different shapes on the water migration of the vadose zone or the lateral supplementary effect of rivers on the vadose zone as an example 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 river valley. The shape of the river valley is set to be a "U" shape. A plurality of 5mm overflow holes are opened at positions corresponding to the shape of the river valley on the silicone plate sandwiched with organic glass baffles. A thin layer of vaseline is applied to the edge of the silicone plate and the wooden board to make them fit tightly.

[0067] S2: Open switches 24 and 27, and use peristaltic pumps 23 and 28 to create stable upstream and downstream water levels;

[0068] S3: Turn on the switch 8 and adjust the peristaltic pump 7 so that its flow rate is the required rainfall intensity;

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

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

[0071] Through the above steps, the water migration process of a certain "U"-shaped river and the vadose zone under different rainfall intensities can be simulated. If the entire sand box simulates the vadose zone, and the first water tank and the second water tank simulate the upstream and downstream of the river, the lateral recharge effect of the river on the vadose zone can be explored.

[0072] In addition to the above embodiments, the present device can also be used to explore the movement of water and solutes in the vadose zone under the interaction of surface water, soil water and groundwater, and the advantages of the artificial rainfall unit of the present invention can be used to explore the possible effects of parameters such as rainfall intensity and rainfall duration on the infiltration process and the movement of water in the vadose zone. The detachability of the device can be used to explore the properties of the vadose zone soil layer and the movement of water in the vadose zone under different surface water bodies, different rainfall conditions and groundwater conditions, and the experimental soil layer can be replaced conveniently. At the same time, by utilizing the surrounding nature of the sensor installation hole and combining the diversity of the surface water simulation of the present device, the spatial diffusion differences of water in the unevenly distributed soil layer of the surface water body can be explored.

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

[0074] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An experimental system for simulating the water migration process in the vadose zone affected by surface water, characterized in that: include: The upper computer module, the water supply unit, the flow collection unit and the artificial rainfall unit, the surface water simulation unit, the vadose zone simulation unit and the groundwater control unit are connected in sequence from top to bottom; wherein the artificial rainfall unit, the surface water simulation unit and the groundwater control unit are all connected to the water supply unit; the artificial rainfall unit, the surface water simulation unit, the vadose zone simulation unit and the groundwater control unit are all connected to the upper 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 rainfall intensity and rainfall duration; The surface water simulation unit is used to simulate surface water, wherein the surface water includes rivers and lakes; The vadose zone simulation unit is used to simulate different soil types; 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 simulation unit, and the groundwater control unit; The flow collection unit is used to collect the overflowed water from the surface water simulation unit and the groundwater control unit; The host computer module is used to receive data from each unit for calculation, processing and display.

2. The experimental system for simulating the water migration process in the vadose zone affected by surface water 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 is a shunt structure; a silicone gasket is provided at the connection between the shunt structure and the rainfall box body; the water inlet end of the shunt 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 on the bottom of the rainfall box, and a plurality of small holes are opened corresponding to the bottom of the rainfall box and the silicone pad, and industrial rubber needles simulating rainfall are installed on the small holes; the flow meter sends the collected data to the upper computer module.

3. The experimental system for simulating the water migration process in the vadose zone affected by surface water according to claim 1, characterized in that: When simulating a river, the main body of the surface water simulation unit is an uncovered sand box, and the top of the sand box is sealed and connected to the bottom of the rainfall box through a silicone gasket; the first water tank and the second water tank are fixedly arranged on the outer walls of the opposite sides of the sand box; the tops of the connections between the first water tank, the second water tank and the sand box are provided with multiple drainage holes; the connections between the first water tank, the second water tank and the sand box are provided with grooves; the first organic glass baffle, the silicone plate, and the second organic glass baffle are sequentially placed in the grooves; wherein the first organic glass baffle, the second organic glass baffle, The baffle is provided with the same water outlet hole correspondingly; the silicone plate is opened according to the experimental requirements of simulating a river; the water inlet of the first water tank is connected to the water supply unit through a conduit, and a peristaltic pump, a switch, and a flow meter are provided on the conduit; the water outlet of the first water tank is connected to the flow collection unit through a conduit; the water inlet of the second water tank is connected to the water supply unit through a conduit, and a peristaltic pump, a switch, and a flow meter are provided on the conduit; the water outlet of the second water tank is connected to the flow collection unit through a conduit; and the flow meter sends the collected data to the upper computer module.

4. The experimental system for simulating the water migration process in the vadose zone affected by surface water according to claim 1, characterized in that: When simulating a lake, the main body of the surface water simulation unit is an uncovered sand box, and the top of the sand box is sealed and connected to the bottom of the rainfall 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 is installed at the bottom of the lake; a row of overflow holes are opened around the sand box at a position level with the surface of the landfill soil; the third water tank, the fourth water tank, the fifth water tank, and the sixth water tank are fixedly arranged around the sand box to receive the water flowing out of the overflow holes; the water outlets of the third water tank, the fourth water tank, the fifth water tank, and the sixth water tank are all connected to the flow collection unit through a conduit; a flow meter is provided on the conduit; the pressure sensor and the flow meter send the collected data to the upper computer module.

5. The experimental system for simulating the water migration process in the vadose zone affected by surface water according to claim 1, characterized in that: The aeration zone simulation unit is composed of a plurality of detachable boxes simulating aeration zones, which are stacked and connected by a detachable bottom plate; the detachable bottom plate is a locking structure, the edge of the detachable bottom plate is fixed by nuts, and a plurality of water permeable holes are arranged in the middle part of the detachable bottom plate; The box is filled with soil layers of different properties according to experimental requirements to simulate the migration of air-enclosed moisture under different circumstances.

6. The experimental system for simulating the water migration process in the vadose zone affected by surface water according to claim 5, characterized in that: Multiple rows of sensor mounting holes are provided around each box body, and the sensor mounting holes are used to install sensors according to the experimental purpose; the sensors send the detected data to the upper computer module in real time; an air pressure measuring hole is provided between two adjacent sensor holes in the same row; the air pressure measuring hole is connected to the double U-shaped tube through a measuring tube.

7. The experimental system for simulating the water migration process in the vadose zone affected by surface water according to claim 1, characterized in that: The groundwater control unit is an underground water tank, the water inlet of the underground water tank is connected to the water supply unit through a conduit, and a peristaltic pump, a switch, and a flow meter are provided on the conduit; the water outlet of the underground water tank body is connected to the flow collection box through a conduit, and a switch and a flow meter are provided on the conduit; the flow meter sends the collected data to the upper computer module.

8. The experimental system for simulating the water migration process in the vadose zone affected by surface water 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 connected via a detachable base plate; the detachable base plate is a locking structure, the edge of the detachable base plate is fixed by nuts, and a plurality of water-permeable holes are arranged in the middle part of the detachable base plate.

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