An experimental device for studying the influence of surface water pollutants on karst groundwater quality

Abstract

The utility model relates to a kind of experimental device of the influence of surface water pollutant on karst groundwater quality, belong to groundwater simulation experimental device technical field, including river main body, water supply circulation driving device, groundwater fixed head device and groundwater pressure measuring device.The utility model can simulate the influence of surface water pollutant on karst groundwater quality under the different recharge-discharge relationship of surface water and multilayer groundwater, and the water level relationship corresponding to different recharge-discharge relationship includes: surface water>porous water>karst water, surface water>karst water>porous water, porous water>surface water>karst water, porous water>karst water>surface water, karst water>porous water>surface water, karst water>surface water>porous water.It can simulate the influence of surface water pollutant on groundwater under different surface river property conditions, and can simulate the influence of surface water pollutant on groundwater under different aquifer property conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of groundwater simulation experiment device, and particularly relates to an experimental device for studying the influence of surface water pollutants on karst groundwater quality. BACKGROUND

[0002] Establishing a sand tank model for physical experiments is one of the important methods for studying the influence of surface water on groundwater. When studying the influence of surface water pollutants on karst groundwater quality, the influence of different surface water and groundwater recharge and discharge relationships usually needs to be considered. There are three relationships between groundwater and surface water: surface water recharges groundwater, surface water discharges groundwater, and surface water and groundwater have no recharge and discharge relationship. Existing surface water / groundwater exchange sand tank models usually do not consider the case of multiple aquifers, and only consider the recharge / discharge of surface water and single-layer groundwater. The influence of surface water on karst groundwater when different recharge relationships exist between surface water and multiple-layer groundwater with pore water is not studied.

[0003] Therefore, it is of great significance to establish an experimental device that can change the mutual recharge and discharge relationship between surface water and multiple-layer groundwater and study the influence of surface water pollutants on karst groundwater. SUMMARY

[0004] The present application discloses an experimental device for studying the influence of surface water pollutants on karst groundwater quality, which can simulate the influence of surface water pollutants on karst groundwater quality under different recharge and discharge relationships between surface water and multiple-layer groundwater (pore water, karst water).

[0005] To achieve the above-mentioned purpose, the technical solution of the present application is:

[0006] An experimental device for studying the influence of surface water pollutants on karst groundwater quality, comprising a river main body, a water supply circulating driving device, a groundwater constant head device and a groundwater pressure measuring device; the river main body comprises, from top to bottom, a main river water tank for simulating the river main body, a No. 1 sand tank for simulating the pore aquifer, and a No. 2 sand tank for simulating the fissure karst aquifer; the water supply circulating device comprises a water supply tank, one end of which is provided with a first water outlet pipe; the first water outlet pipe is provided with a No. 1 valve; the first water outlet pipe is used to supply water to the main river water tank; one end of the main river water tank is provided with an extendable overflow plate, and the other end is connected with a second water outlet pipe; the extendable overflow plate is connected with a first drainage water tank on the side wall of the main river water tank outside; the first drainage water tank is connected with the water supply tank through a first connecting pipe; the first connecting pipe is provided with a No. 2 centrifugal pump; the main river water tank on one side of the second water outlet pipe is provided with a second drainage water tank; the second water outlet pipe is provided with a No. 2 valve; the second drainage water tank is connected with the water supply tank through a second connecting pipe; the second connecting pipe is provided with a No. 1 centrifugal pump; the No. 1 sand tank and the No. 2 sand tank are respectively connected with a third water outlet pipe and a fourth water outlet pipe on the side wall of the first drainage water tank; the third water outlet pipe is provided with a No. 3 valve; the fourth water outlet pipe is provided with a No. 4 valve; the groundwater constant head device comprises a No. 1 constant head water tank and a No. 2 constant head water tank; the No. 1 constant head water tank is connected with the No. 1 sand tank away from the third water outlet pipe through a third connecting pipe; the No. 2 constant head water tank is connected with the No. 2 sand tank away from the fourth water outlet pipe through a fourth connecting pipe; the third connecting pipe and the fourth connecting pipe are respectively provided with a No. 5 valve and a No. 6 valve; the groundwater pressure measuring device comprises a pressure measuring plate and a pressure measuring pipe; the side walls of the No. 1 sand tank and the No. 2 sand tank are respectively arranged with a plurality of pressure measuring pipe connecting holes in a matrix; each pressure measuring pipe connecting hole is sealingly and fixedly connected with the bottom end of one pressure measuring pipe; the upper part of the pressure measuring pipe is fixedly connected with the outer surface of the side pressure plate in the longitudinal direction.

[0007] The experimental device adjusts the water level of surface water, the water level of pore water and the water level of karst water to simulate different recharge-discharge relationships of surface water, pore water and karst water, and simulates the influence of surface water pollutants on pore groundwater and karst groundwater quality for different recharge-discharge relationships; the water level relationships corresponding to different recharge-discharge relationships include: surface water > pore water > karst water, surface water > karst water > pore water, pore water > surface water > karst water, pore water > karst water > surface water, karst water > pore water > surface water, and karst water > surface water > pore water.

[0008] Preferably, the main river water tank is provided with linear sliding grooves on both sides of one end, the plate body of the telescopic overflow plate is respectively connected with the corresponding linear sliding grooves in a sealing sliding manner, and the inner surface of the plate body is sealingly and slidingly connected with the end of the bottom plate of the main river water tank; the lower end of the plate body extends downward through the bottom end of the linear sliding groove, and the height of the overflow water surface in the main river water tank is adjusted by pulling the plate body up and down.

[0009] Preferably, the pressure measuring pipe distinguishes the water pressure at the connecting hole of each pressure measuring pipe by observing the water level height in the pipe, and the pressure measuring pipe comprises an integrated horizontal section and a vertical section, and the end of the horizontal section is connected with the connecting hole of the pressure measuring pipe through a hose.

[0010] Preferably, the main river water tank, the 1# sand tank, the 2# sand tank, the water supply tank, the first drainage tank, the second drainage tank, the 1# constant head tank and the 2# constant head tank are all made of transparent organic glass plates and are all in the shape of a cuboid; the upper surface of the bottom plate of the main river water tank and the upper surface of the bottom of the 1# sand tank are both paved with a metal screen.

[0011] Preferably, the main river water tank is provided with glass beads for simulating river bottom mud; the 1# sand tank is filled with experimental quartz sand; the 2# sand tank is filled with bricks with gaps between the bricks; the height of the 1# sand tank is significantly smaller than the height of the 2# sand tank, for simulating the large thickness of fissure karst aquifer and the relatively thin thickness of pore aquifer in northern karst areas.

[0012] Preferably, the experimental device is used to simulate the influence of surface water pollutants on groundwater under different surface river conditions, and is used to simulate the influence of surface water pollutants on groundwater under different aquifer conditions, by quantitatively controlling the properties of surface river, such as flow rate and river bottom mud permeability coefficient, and the properties of aquifer, such as permeability coefficient, porosity and solution porosity.

[0013] Preferably, the 1# sand tank and the 2# sand tank are separated only by a layer of metal screen, for simulating that the pore aquifer in northern karst areas develops on the top of the fissure karst aquifer.

[0014] Preferably, the 2# valve is opened to simulate the flow of surface water, and the opening degree of the 2# valve is adjusted to control the size of the surface water flow; the third water outlet pipe and the fourth water outlet pipe are respectively used for sampling the water discharged from the 1# sand tank and the 2# sand tank.

[0015] Preferably, the 1# constant head tank and the 2# constant head tank are respectively provided with a 1# float ball valve and a 2# float ball valve, and the 1# float ball valve and the 2# float ball valve are respectively connected with the first water inlet pipe and the second water inlet pipe.

[0016] The experimental device for studying the influence of surface water pollutants on karst underground water quality has the beneficial effects that:

[0017] The present application can simulate the influence of surface water pollutants (sulfate, nitrate, etc.) on karst underground water quality under different recharge-discharge relationships of surface water and multi-layer underground water (pore water, karst water), and the water level relationships corresponding to different recharge-discharge relationships include: surface water > pore water > karst water, surface water > karst water > pore water, pore water > surface water > karst water, pore water > karst water > surface water, karst water > pore water > surface water, and karst water > surface water > pore water. The influence of surface water pollutants on underground water under different surface river properties (flow rate, river bottom sediment permeability coefficient) can be simulated, and the influence of surface water pollutants on underground water under different aquifer properties (permeability coefficient, porosity, dissolution porosity) can be simulated.

[0018] Drawings

[0019] Figure 1 The front view of the present application;

[0020] Figure 2 The bottom plate diagram of the main river channel water tank of the present application;

[0021] Figure 3 The schematic diagram of the metal screen of the present application;

[0022] Figure 4 The layout diagram of the pressure measuring pipe connecting hole of the present application;

[0023] Figure 5 The side view structure schematic diagram of the telescopic overflow plate of the present application;

[0024] 1, water supply water tank; 2, main river channel water tank; 2-1, straight sliding chute; 3, 1# sand tank; 4, 2# sand tank; 5, beaker; 6, second drainage water tank; 7, 1# constant head water tank; 8, 2# constant head water tank; 9, 1# valve; 10, 2# valve; 11, 3# valve; 12, 4# valve; 13, 5# valve; 14, 6# valve; 15, pressure measuring pipe connecting hole; 16, 1# water outlet; 17, pressure measuring plate; 18, telescopic overflow plate; 19, 1# centrifugal pump; 20, 2# centrifugal pump; 21, leakage hole; 22, 1# floating ball valve; 23, 2# floating ball valve; 24, metal screen; 25, first water inlet pipe; 26, second water inlet pipe. DETAILED DESCRIPTION

[0025] The following description is only a preferred embodiment of the present application, and is not intended to limit the protection scope of the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0026] Example 1

[0027] An experimental apparatus for studying the impact of surface water pollutants on the quality of karst groundwater, such as... Figures 1-5 As shown, the system includes a main river channel, a water supply and circulation drive device, a groundwater head control device, and a groundwater pressure measuring device. The main river channel, from top to bottom, includes a main channel water tank 2 to simulate the main river channel, a No. 1 sand tank 3 to simulate a porous aquifer, and a No. 2 sand tank 4 to simulate a fractured karst aquifer. The water supply and circulation device includes a water supply tank 1, with a first outlet pipe at one end of the water supply tank 1. The first outlet pipe is equipped with a No. 1 valve 9 and is used to supply water to the main channel water tank 2. One end of the main channel water tank 2 is equipped with a retractable overflow plate 18, and the other end is connected to a second outlet pipe. A first drainage tank (not marked in the figure, used to collect overflow water from the main channel water tank) is connected to the side wall of the main channel water tank 2, outside the retractable overflow plate 18. The first drainage tank is connected to the water supply tank via a first connecting pipe. A centrifugal pump 20 (#2) is installed on the first connecting pipe. A second drainage tank 6 is located outside the main channel water tank 2 on one side of the second outlet pipe. The second outlet pipe is equipped with a valve 10 (#2). The second drainage tank 6 is connected to the main channel water tank 2 via a first connecting pipe. The second connecting pipe is connected to the water supply tank 1, and a centrifugal pump 19 is installed on the second connecting pipe; the sand tank 3 and sand tank 4 are located on the side wall of the first drainage tank and are respectively connected to the third outlet pipe and the fourth outlet pipe, respectively. The third outlet pipe is equipped with a valve 11, and the fourth outlet pipe is equipped with a valve 12; the groundwater constant head device includes a constant head tank 7 and a constant head tank 8. The constant head tank 7 is connected to the end of the sand tank 3 away from the third outlet pipe through the third connecting pipe. The #2 constant head water tank 8 is connected to the end of the #2 sand tank 4 away from the fourth outlet pipe via the fourth connecting pipe. The third and fourth connecting pipes are respectively equipped with valve #5 13 and valve #6 14. The groundwater pressure measuring device includes a pressure measuring plate 17 and pressure measuring pipes (not marked in the figure). Several pressure measuring pipe connection holes 15 are arranged in a matrix on the side walls of the #1 sand tank 3 and #2 sand tank 4. Each pressure measuring pipe connection hole 15 is sealed and fixedly connected to the bottom end of a pressure measuring pipe. The upper part of the pressure measuring pipe is fixedly connected longitudinally to the outer surface of the side pressure plate 17. The water supply and circulation device is used for supplying water to the main river water tank and for water circulation between the first and second drainage water tanks and the water supply tank.

[0028] Example 2

[0029] Based on Example 1, this example discloses:

[0030] like Figure 1 , 5As shown, the main river water tank 2 one end of both sides is provided with linear chute 2-1, the plate body of the telescopic overflow plate 18 is respectively connected with corresponding linear chute 2-1 sealing sliding connection, the inner surface of the plate body and the end of the main river water tank 2 bottom plate sealing sliding connection;The lower end of the plate body passes through the bottom end of the linear chute and extends downward, and the height of the overflow water in the main river water tank is adjusted by pulling the plate body up and down;The bottom plate of the main river water tank 2 is evenly distributed with a plurality of leakage holes 21.

[0031] In this embodiment, the sealing sliding connection between the telescopic overflow plate and the linear chute and the end of the bottom plate is prior art, which is not described in detail. Of course, the telescopic overflow plate can also adopt other structures that can realize the above functions.

[0032] Embodiment 3

[0033] Based on embodiments 1 and 2, this embodiment discloses:

[0034] As shown in Figure 1 , 4 , the pressure measuring pipe distinguishes the water pressure at each pressure measuring pipe connecting hole by observing the water level in the pipe, the pressure measuring pipe includes an integrated horizontal section and a vertical section (as shown in Figure 4 , the end of the horizontal section is connected with the pressure measuring pipe connecting hole through a hose. In addition to observing the water level to observe the water pressure, a pressure sensor can also be provided on the pressure measuring pipe body at the same height as the pressure measuring pipe connecting hole to collect the water level pressure at the height of the pressure measuring pipe connecting hole.

[0035] Embodiment 4

[0036] Based on embodiments 1, 2 and 3, this embodiment discloses:

[0037] As shown in Figure 1 , the main river water tank 2, the 1# sand tank 3, the 2# sand tank 4, the water supply tank 1, the first drainage tank, the second drainage tank 6, the 1# constant head tank 7, and the 2# constant head tank 8 are all made of transparent organic glass plates and are all rectangular parallelepiped-shaped, which is convenient for observation during the experiment;The upper surface of the bottom plate of the main river water tank 2 and the upper surface of the bottom of the 1# sand tank 3 are both paved with metal screen 24.

[0038] As shown in Figure 1 , the main river water tank 2 is provided with glass beads for simulating river bottom sand;The 1# sand tank 3 is filled with experimental quartz sand for simulating pore water-bearing layer;The 2# sand tank 4 is filled with bricks with gaps between them for simulating fissure karst water-bearing layer;The height of the 1# sand tank is significantly smaller than the height of the 2# sand tank, which is used to simulate the large thickness of fissure karst water-bearing layer and the relatively thin thickness of pore water-bearing layer in northern karst areas.

[0039] Example 5

[0040] Based on Example 4, this example discloses:

[0041] like Figure 1 As shown, there is no plexiglass partition between the No. 1 sand box 3 and the No. 2 sand box 4. They are separated only by a layer of metal mesh 24, which is used to simulate the development of porous aquifers in the northern karst region at the top of fractured karst aquifers.

[0042] Example 6

[0043] Based on Example 5, this example discloses:

[0044] like Figure 1 As shown, when valve #2 10 is opened, it simulates the flow of surface water; the flow rate of surface water is controlled by adjusting the opening degree of valve #2 10; the third and fourth outlet pipes are used for sampling the water discharged from sand box #1 3 and sand box #2 4, respectively. Through sampling and testing, the impact of surface water pollutants on the quality of karst groundwater and pore water groundwater can be determined.

[0045] like Figure 1 As shown, the groundwater head control device is used for adjusting the head of sand tank #1 and sand tank #2. The left side of the head control tank #1 in the groundwater head control device is connected to sand tank #1 by a rubber tube, and valve #5 is also provided. The left side of the head control tank #2 in the groundwater head control device is connected to sand tank #2 by a rubber tube, and valve #6 is also provided.

[0046] like Figure 1 As shown, the No. 1 constant head water tank 7 and the No. 2 constant head water tank 8 are respectively equipped with a No. 1 float valve 22 and a No. 2 float valve 23, which are connected to the first inlet pipe 25 and the second inlet pipe 26, respectively. In this way, the water level in the No. 1 constant head water tank and the No. 2 constant head water tank can be kept stable.

[0047] Example 7

[0048] Based on the above embodiments, this embodiment discloses a method for using the present invention:

[0049] (1) Before the experiment, water was added to the No. 1 constant head water tank 7 and the No. 2 constant head water tank 8. The No. 5 valve 13 and the No. 6 valve 14 were opened to fill the sand tank with water to simulate the underground aquifer. Then the No. 5 valve 13 and the No. 6 valve 14 were closed.

[0050] (2) Before the experiment, close the 2# valve 10 and open the 1# valve 9, so that the water tank 1 supplies water to the main river tank 2, simulating the surface river water body, and the water level reaches the upper end of the telescopic overflow plate, then close the 1# valve 9.

[0051] (3) At the beginning of the experiment, adjust the vertical height of the 1# constant head tank 7 and the 2# constant head tank 8 as needed, to adjust the water level of the pore aquifer and the fissure karst aquifer.

[0052] (4) At the beginning of the experiment, adjust the telescopic overflow plate 18 as needed, to adjust the surface water level.

[0053] (5) At the beginning of the experiment, when simulating the condition that the surface water in the main river tank 2 recharges the groundwater in the 1# sand tank 3 and the 2# sand tank 4, adjust the groundwater level in the 1# sand tank 3 and the 2# sand tank 4 and the surface water level in the main river tank 2 at the same time, so that the surface water level is higher than the groundwater level; when simulating the condition that the groundwater in the 1# sand tank 3 and the 2# sand tank 4 discharges to the surface water in the main river tank 2, adjust the groundwater level in the 1# sand tank 3 and the 2# sand tank 4 and the surface water level in the main river tank 2 at the same time, so that the surface water level is lower than the groundwater level.

[0054] (6) At the beginning of the experiment, first open the 2# valve 10 to make the surface water flow, then open the 5# valve 13 and the 6# valve 14 to connect the 1# constant head tank 7 and the 2# constant head tank 8, simulate the groundwater level height, according to the law of fluid statics, the height of the water level in the 1# constant head tank 7 and the 2# constant head tank 8 when stable, which corresponds to the groundwater level height in the 1# sand tank 3 and the 2# sand tank 4 respectively.

[0055] (7) During the experiment, the opening degree of the 2# valve 10 can be adjusted as needed to adjust the flow rate of the surface water, and the beaker 5 can be used to collect the surface water in unit time to measure the flow rate of the surface water.

[0056] (8) During the experiment, the 3# valve 11 and the 4# valve 12 can be opened as needed to sample and detect the water samples of the 1# sand tank 3 and the 2# sand tank 4.

[0057] (9) During the experiment, the water level changes in the 1# sand tank 3 and the 2# sand tank 4 can be observed through the pressure measuring tube.

[0058] (10) The size and material of the glass beads at the bottom of the main river tank 2 can be adjusted as needed to change the properties of the river bottom.

[0059] (11) The filling material in the 1# sand tank 3 and the 2# sand tank 4 can be adjusted as needed to change the properties of the aquifer.

[0060] In summary, the present application can simulate the influence of surface water pollutants (sulfate, nitrate, etc.) on karst groundwater quality under different recharge-discharge relationships of surface water and multi-layer groundwater (pore water, karst water), and can meet the needs of various experimental scenarios by quantitatively controlling the properties of surface river (flow rate, river bottom sediment permeability coefficient) and aquifer (permeability coefficient, porosity, solubility), which is simple, economical and practical, and has important significance for the study of the influence of surface water on karst groundwater pollution.

Claims

1. An experimental apparatus for studying the impact of surface water pollutants on the quality of karst groundwater, characterized by: The system includes a main river channel, a water supply and circulation drive device, a groundwater head control device, and a groundwater pressure measuring device. The main river channel, from top to bottom, includes a main channel water tank simulating the main river channel, a No. 1 sand tank simulating a porous aquifer, and a No. 2 sand tank simulating a fractured karst aquifer. The water supply and circulation drive device includes a water supply tank. One end of the water supply tank has a first outlet pipe with a No. 1 valve, which supplies water to the main channel water tank. One end of the main channel water tank has a retractable overflow plate, and the other end is connected to a second outlet pipe. A first drainage tank is connected to the side wall of the main channel water tank outside the retractable overflow plate. The first drainage tank is connected to the water supply tank via a first connecting pipe, and a No. 2 centrifugal pump is installed on the first connecting pipe. A second drainage tank is located outside the main channel water tank on one side of the second outlet pipe, and the second outlet pipe has a No. 2 valve. The second drainage tank is connected to the main channel water tank via a second connecting pipe. The pipe is connected to the water supply tank. A centrifugal pump (#1) is installed on the second connecting pipe. Sand tanks #1 and #2 are located on the side wall of the first drainage tank and are respectively connected to a third and fourth outlet pipe. A valve (#3) is installed on the third outlet pipe, and a valve (#4) is installed on the fourth outlet pipe. The groundwater head control device includes a head control tank (#1) and a head control tank (#2). The head control tank (#1) is connected to the end of sand tank #1 furthest from the third outlet pipe via the third connecting pipe. The No. 2 constant head water tank is connected to the end of the No. 2 sand box away from the fourth outlet pipe through the fourth connecting pipe. The third and fourth connecting pipes are respectively equipped with valve No. 5 and valve No.

6. The groundwater pressure measuring device includes a pressure measuring plate and pressure measuring pipes. The side walls of the No. 1 and No. 2 sand boxes are respectively arranged in a matrix with several pressure measuring pipe connection holes. Each pressure measuring pipe connection hole is sealed and fixedly connected to the bottom end of a pressure measuring pipe. The upper part of the pressure measuring pipe is fixedly connected to the outer surface of the pressure measuring plate along the longitudinal direction. The experimental setup simulates different recharge and discharge relationships between surface water, pore water, and karst water by adjusting the water levels of surface water, pore water, and karst water. It also simulates the impact of surface water pollutants on the water quality of pore groundwater and karst groundwater for different recharge and discharge relationships. The water level relationships corresponding to different recharge and discharge relationships include: surface water > pore water > karst water, surface water > karst water > pore water, pore water > surface water > karst water, pore water > karst water > surface water, karst water > pore water > surface water, and karst water > surface water > pore water.

2. The experimental apparatus for studying the impact of surface water pollutants on karst groundwater quality as described in claim 1, characterized in that: The main channel water tank has straight sliding grooves on both sides at one end. The two ends of the retractable overflow plate are respectively sealed and slidably connected to the corresponding straight sliding grooves. The inner surface of the plate is sealed and slidably connected to the end of the bottom plate of the main channel water tank. The lower end of the plate passes through the bottom end of the straight sliding groove and extends downward. The overflow water level in the main channel water tank can be adjusted by pulling the plate up and down. Several leakage holes are evenly distributed on the bottom plate of the main channel water tank.

3. The experimental apparatus for studying the impact of surface water pollutants on the quality of karst groundwater as described in claim 2, characterized in that: The pressure measuring tube compares the water pressure difference at each pressure measuring tube connection hole by observing the water level height inside the tube. The pressure measuring tube includes an integrally connected horizontal section and a vertical section, and the end of the horizontal section is connected to the pressure measuring tube connection hole through a flexible tube.

4. The experimental apparatus for studying the impact of surface water pollutants on karst groundwater quality as described in claim 3, characterized in that: The main channel water tank, No. 1 sand tank, No. 2 sand tank, water supply tank, first drainage tank, second drainage tank, No. 1 constant head water tank, and No. 2 constant head water tank are all made of transparent plexiglass sheets and are all rectangular in shape; the upper surface of the bottom plate of the main channel water tank and the upper surface of the bottom of No. 1 sand tank are covered with metal screens.

5. The experimental apparatus for studying the impact of surface water pollutants on karst groundwater quality as described in claim 4, characterized in that: The main channel water tank is equipped with glass beads to simulate riverbed sediment; the No. 1 sand tank is filled with experimental quartz sand; the No. 2 sand tank is filled with bricks with gaps between them; the height of the No. 1 sand tank is significantly smaller than the height of the No. 2 sand tank, which is used to simulate the large thickness of the fissure karst aquifer and the relatively thin thickness of the pore aquifer in the northern karst region.

6. The experimental apparatus for studying the impact of surface water pollutants on karst groundwater quality as described in claim 5, characterized in that: The experimental setup described above is used to simulate the impact of surface water pollutants on groundwater under different surface river properties, namely flow velocity, riverbed sediment permeability coefficient, and aquifer properties, namely permeability coefficient, porosity, and dissolution porosity, by quantitatively controlling surface river properties, namely flow velocity, riverbed sediment permeability coefficient, and aquifer properties, and to simulate the impact of surface water pollutants on groundwater under different aquifer properties.

7. The experimental apparatus for studying the impact of surface water pollutants on karst groundwater quality as described in claim 6, characterized in that: There is no plexiglass partition between the No. 1 sand box and the No. 2 sand box; they are separated only by a layer of metal mesh, which is used to simulate the development of porous aquifers at the top of fractured karst aquifers in northern karst areas.

8. The experimental apparatus for studying the impact of surface water pollutants on the quality of karst groundwater as described in claim 7, characterized in that: When valve #2 is opened, it simulates the flow of surface water; the flow rate of surface water is controlled by adjusting the opening degree of valve #2; the third and fourth water outlet pipes are used for sampling the water discharged from sand box #1 and sand box #2, respectively.

9. An experimental apparatus for studying the impact of surface water pollutants on the quality of karst groundwater as described in claim 8, characterized in that: The No. 1 constant head water tank and the No. 2 constant head water tank are respectively equipped with a No. 1 float valve and a No. 2 float valve, which are respectively connected to the first water inlet pipe and the second water inlet pipe.

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