A research method and application for studying soil water recharge and surface vegetation conditions caused by groundwater evaporation.

Abstract

The application discloses a research method of phreatic evaporation recharge soil water and surface vegetation conditions and application thereof in research of ecological restoration of semi-arid grassland open-pit mine area. The method of the application injects a certain amount of hydrogen and oxygen isotope tracer liquid into a to-be-measured soil layer of a certain depth to simulate a phreatic surface of the to-be-measured depth, thereby avoiding the problems of blind search for phreatic levels of different depths in the prior art field test, a very large number of drill holes, huge workload, and certain field phreatic depth which is difficult to change artificially and thus is not easy to carry out target depth phreatic influence test, and greatly facilitating the test research and saving the test cost. In addition, the method of the application has high test result reliability and small engineering implementation difficulty through in-situ test and injection of the hydrogen and oxygen isotope tracer liquid into the to-be-measured soil layer of the certain depth through a plastic hose.

Description

Technical Field

[0001] This invention belongs to the fields of soil science and environmental science, specifically relating to a research method for the recharge of soil water by groundwater evaporation and the condition of surface vegetation, and its application in the study of ecological restoration of semi-arid grassland open-pit mining areas. Background Technology

[0002] Soil water and groundwater are interconvertible. The conversion of soil water into groundwater is mainly manifested by precipitation and irrigation under planting conditions, which infiltrates and replenishes groundwater. The conversion of groundwater into soil water is mainly manifested by groundwater evaporation.

[0003] The formation and rates of groundwater infiltration recharge and evaporation are primarily determined by factors such as the lower interface of the vadose zone (groundwater level), the distribution of soil moisture energy and quantity, and water conduction capacity. Regardless of the complexity of the soil water potential distribution in the vadose zone soil profile, as long as the soil water potential gradient in the adjacent area above the groundwater level is less than zero, soil moisture will migrate upwards, causing groundwater evaporation and the conversion of groundwater into soil water. Studying the interconversion relationship between groundwater and soil water has significant theoretical and practical value for in-depth research on grassland vegetation restoration and the development of rational water-saving irrigation schemes.

[0004] In their article "A Study on Shallow Groundwater and Soil Water Dynamics in the Shihezi Reclamation Area," Xu Chunyan et al. pointed out that under different groundwater depths in wasteland and cultivated land in the Shihezi Reclamation Area of ​​Xinjiang, they determined the soil moisture characteristics of the soil profiles by sampling and drying. They divided the groundwater depth in the Shihezi Reclamation Area into two segments: less than 2m and greater than 3m. Through statistical analysis, they established empirical formulas to describe the relationship between shallow groundwater depth and soil moisture in cultivated land and wasteland. They found that the relationship between depth and soil moisture in cultivated land is a quadratic function, while the relationship between depth and soil moisture in wasteland is a power function, showing a negative correlation. This study roughly describes the characteristics of soil moisture replenishment under different groundwater depths in wasteland and cultivated land in the Shihezi Reclamation Area. However, this experimental design cannot effectively explain the quadratic function relationship between depth and soil moisture in cultivated land, and the method only roughly describes the strength of groundwater replenishment at different depths, without distinguishing or quantifying the sources of soil moisture.

[0005] Patent CN108267562A discloses a soil stable isotope labeling device and method. It involves using an extractor to collect a complete soil column, a soil filler to receive the column, and small holes at different depths. A solution distributor is connected to these holes via multiple plastic tubes. A constant flow pump is connected to the distributor; the pump rotates forward to pump the solution and reverses to draw it in. A reservoir and the pump are included to provide the labeling solution to the soil filler during pumping. While this method can effectively inject stable soil isotopes into the soil layer and is effective for shallow soil isotope labeling experiments, it relies on a soil filler, which isolates the soil from the surrounding strata. Furthermore, the method of using a constant flow pump to draw the soil solution in reverse is difficult to implement in soils with low moisture content, making it difficult to determine the isotope content in the dry surface soil. This method has drawbacks for studying groundwater recharge from evaporation in semi-arid mining dump environments, including the isolation of lateral soil connections, low water content, and difficulty in measuring isotopes in dry surface soil.

[0006] Therefore, developing a research method that can quantitatively study the impact of groundwater evaporation on soil water and surface vegetation is of great significance for in-depth research on ecological restoration in semi-arid grassland areas, especially the ecological management of open-pit mines in semi-arid grassland areas, and for formulating reasonable water-saving irrigation schemes. Summary of the Invention

[0007] To address the problems existing in the prior art, the present invention aims to provide a method for studying the impact of groundwater evaporation on soil water and surface vegetation recharge. This invention employs an in-situ experiment, using hydrogen and oxygen isotopes injected into soil layers at different depths to simulate groundwater levels at different burial depths. After a period of time, the hydrogen and oxygen isotope content at the experimental location and at different depths in the surrounding surface vegetation is analyzed to describe the transport height of groundwater recharge to the soil under different groundwater burial depths, thereby determining the depth threshold for groundwater evaporation recharge to the soil. This method is simple and easy to implement, provides excellent labeling effects for groundwater evaporation recharge to the soil, and the in-situ experiment method maximizes the reproduction of real groundwater and soil water transport characteristics, resulting in reliable and credible experimental results.

[0008] Therefore, the first aspect of the present invention provides a method for studying the recharge of soil water by groundwater evaporation and the condition of surface vegetation, which includes the following steps:

[0009] (1) Delineate the test area at the test site, and take samples to measure the background values ​​of hydrogen and oxygen isotopes of the target burial depth, soil layers at each design depth, and surface vegetation.

[0010] (2) Inject hydrogen and oxygen isotope tracer solution into the soil layer at the target burial depth to simulate the groundwater surface at the target burial depth and set the observation period;

[0011] (3) After the observation period, soil samples were taken from the soil layers at each designed depth in the vertical direction between the injection point of the hydrogen and oxygen isotope tracer liquid and the ground surface. Hydrogen and oxygen isotope measurements were performed on the soil samples and the vegetation at the corresponding ground surface location of the injection point of the hydrogen and oxygen isotope tracer liquid to obtain the hydrogen and oxygen isotope measurement values. Combined with the hydrogen and oxygen isotope background values ​​obtained in step (1), the replenishment of soil water and surface vegetation by groundwater evaporation at the target burial depth was analyzed.

[0012] According to some embodiments of the present invention, the amount of hydrogen and oxygen isotope tracer solution injected into the soil layer at the target burial depth is not less than 1L, preferably 1-1.5L.

[0013] In this invention, "hydrogen and oxygen isotope background value" refers to the information on hydrogen and oxygen isotopes contained in the soil layer and surface vegetation under normal conditions without being labeled with hydrogen and oxygen isotope tracer solution, including but not limited to the distribution and amount of hydrogen and oxygen isotopes contained therein.

[0014] According to the present invention, the "hydrogen isotope tracer injection site" is not limited to a specific injection location. Those skilled in the art will understand that the hydrogen isotope tracer will infiltrate the soil layer at the target burial depth. In the present invention, the infiltration area of ​​the hydrogen isotope tracer in the soil layer at the target burial depth is included within the range of the hydrogen isotope tracer injection site.

[0015] According to some embodiments of the present invention, the replenishment of soil water and surface vegetation by the target depth groundwater evaporation includes: the depth threshold of the target depth groundwater evaporation replenishing soil water, the utilization of the target depth groundwater by surface vegetation, and the transport pattern of the soil water replenished by the target depth groundwater evaporation in the soil layer.

[0016] According to some embodiments of the present invention, soil samples are obtained by sampling at the injection site of the hydrogen and oxygen isotope tracer and at soil layers at various designed depths in the vertical direction between the injection site of the hydrogen and oxygen isotope tracer and the ground surface, and the hydrogen and oxygen isotope values ​​of the soil samples are measured. Combined with the hydrogen and oxygen isotope background values ​​of the soil layers obtained in step (1), the rising height of the soil water labeled by hydrogen and oxygen isotopes is analyzed, thereby determining the depth threshold for the groundwater recharge of the target burial depth by evaporation.

[0017] According to some embodiments of the present invention, the height at which the hydrogen and oxygen isotope tracer solution evaporates in the soil layer to replenish soil water, plus the height of the capillary saturation zone above the groundwater level in the test area, is the depth threshold for groundwater evaporation to replenish soil water, for example, in the case where there is no vegetation growth on the ground surface.

[0018] According to some embodiments of the present invention, the sum of the water isotope rise height shown by the hydrogen and oxygen isotope tracer test, the height of the soil capillary saturation zone above the groundwater level in the test area, and the water absorption depth of the surface vegetation roots is the depth threshold for groundwater evaporation to replenish soil water, for example, when there is vegetation growing on the surface.

[0019] According to some embodiments of the present invention, soil samples are obtained by sampling at the injection site of the hydrogen and oxygen isotope tracer liquid and at various designed depths of soil layers in the vertical direction between the liquid and the surface, and the hydrogen and oxygen isotope values ​​of the soil samples are measured. Combined with the hydrogen and oxygen isotope background values ​​of the soil layer obtained in step (1), the migration pattern of soil water replenished by groundwater evaporation in the soil layer is analyzed.

[0020] According to some embodiments of the present invention, by analyzing the distribution characteristics of the root system of surface vegetation in the soil of the test area, the hydrogen and oxygen isotope values ​​of the vegetation at the corresponding surface location where the hydrogen and oxygen isotope tracer solution was injected are measured. Combined with the background value of hydrogen and oxygen isotopes of the surface vegetation obtained in step (1), the utilization of the surface vegetation for the target burial depth groundwater is analyzed.

[0021] According to some embodiments of the present invention, the target burial depth is 30cm-10m.

[0022] According to some embodiments of the present invention, for soil in which no plants grow, the target burial depth is 50cm-10m.

[0023] According to some embodiments of the present invention, for soil in which plants grow, the target burial depth is 100cm-10m.

[0024] According to some preferred embodiments of the present invention, the target burial depth is 2-5m.

[0025] According to some embodiments of the present invention, the design depth is less than the target burial depth, and the soil layer depth corresponding to at least 5 cm intervals from the ground surface, preferably ≥10 cm intervals.

[0026] According to some embodiments of the present invention, the number of design depths is at least three.

[0027] According to some embodiments of the present invention, the observation period is 24 hours to 12 months, preferably 1 to 9 months, and more preferably 3 to 6 months.

[0028] According to some embodiments of the present invention, the study is conducted during a dry season with little rainfall, and the observation period is 3-6 months of the dry season with little rainfall.

[0029] According to some embodiments of the present invention, the step (2) of injecting the hydrogen and oxygen isotope tracer liquid into the soil layer at the target burial depth is achieved by a method comprising the following steps: drilling a borehole at the same depth as the target burial depth and preserving the complete structure of the drilled soil sample; placing a weight at one end of a plastic hose with a length greater than or equal to the target burial depth into the bottom of the borehole and injecting the hydrogen and oxygen isotope tracer liquid into the soil layer at the depth to be measured through the plastic hose, and then quickly backfilling the drilled soil sample into the borehole.

[0030] According to some embodiments of the present invention, when the plastic hose is lowered into the borehole, a weight is attached to one end of the plastic hose to facilitate its smooth lowering to the bottom of the borehole, and the other end is slightly tightened at the borehole opening to prevent the plastic hose from bending and causing blockage.

[0031] According to some embodiments of the present invention, the diameter of the drill hole is 8-12 cm. In some preferred embodiments, the diameter of the drill hole is 10 cm.

[0032] According to some embodiments of the present invention, in steps (1) and (3), a soil column is obtained by drilling a sampling hole at the same depth as the target burial depth and preserving the complete structure of the drilled soil sample, and soil samples are obtained at each designed depth corresponding to the soil column to determine the background value of hydrogen and oxygen isotopes and / or the measured value of hydrogen and oxygen isotopes.

[0033] According to some embodiments of the present invention, the diameter of the sampling hole is 4-6 cm. In some preferred embodiments, the diameter of the sampling hole is 5 cm.

[0034] According to some embodiments of the present invention, the distance from the center of the sampling hole to the center of the hydrogen and oxygen isotope injection site is <14.5cm, preferably less than 12cm.

[0035] According to some embodiments of the present invention, the surface vegetation is at least one of herbaceous plants and shrubs, preferably at least one of alfalfa, shrubs such as Caragana korshinskii and small-leaved Caragana.

[0036] The second aspect of the present invention provides an application of the method described in the first aspect of the present invention in the study of ecological restoration in semi-arid grassland open-pit mining areas, especially the situation of groundwater evaporation recharge of soil water and surface vegetation in semi-arid grassland open-pit mining areas.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1) This invention injects a certain amount of tracer liquid into the soil layer to form a local saturation zone at the depth to be measured, simulating the capillary saturation zone formed in the soil layer above the water table. Thus, by injecting tracer liquid at different burial depths, the water table at different burial depths can be simulated. This avoids the problems of blindly searching for water table at different burial depths in existing field tests, which requires drilling a large number of holes, resulting in a huge workload, and the difficulty in conducting tests on the impact of water table on the target burial depth due to the fixed burial depth in the field. This invention greatly facilitates experimental research and saves costs.

[0039] 2) The method of the present invention can maximize the reproduction of the influence of soil structure characteristics, climate factors and vegetation type in the study area by conducting in-situ experiments in open spoil heaps in semi-arid grasslands, for example. The experimental results are reliable and have high credibility.

[0040] 3) The method of the present invention simulates the groundwater surface at different depths by injecting hydrogen and oxygen isotope tracer liquid into soil layers at different burial depths, and injects the hydrogen and oxygen isotope tracer liquid into the corresponding depth soil layer through a plastic hose. This avoids the defect of isolating the lateral connection of the soil in the prior art, and can be applied to groundwater at different depths. It has a good marking effect on groundwater evaporation and replenishment of soil water. The method is simple and easy to implement, and the engineering implementation is not difficult.

[0041] 4) The method of this invention utilizes hydrogen and oxygen stable isotope tracing technology to quantitatively analyze the replenishment of soil water and surface vegetation by groundwater at different burial depths. It can study the influence of different groundwater burial depths on the vertical transport height of soil moisture, obtain the distribution characteristics of groundwater replenishment to the vadose zone soil water at different burial depths through isotope transport in the vadose zone, and preliminarily determine the depth threshold for groundwater evaporation replenishment to soil water and the utilization of groundwater at different depths by surface vegetation. This provides a theoretical basis for hydrological factors for the formulation and implementation of future ecological governance plans for mining areas. Attached Figure Description

[0042] Figure 1 A schematic diagram showing the injection of isotope tracer solution into soil layers at different depths in an open spoil heap.

[0043] Figure 2 A schematic diagram showing the upward movement and distribution of isotope tracer solutions injected at different depths.

[0044] Figure 3 A schematic diagram showing the distribution of isotope tracer solutions injected at different depths at the end of the observation period. Detailed Implementation

[0045] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply.

[0046] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0047] Hydrogen and oxygen isotopes (δ¹⁸O) in soil water and plant roots, stems and leaves 2 H, δ 18 O) The determination was performed using a liquid water isotope analyzer.

[0048] Example 1

[0049] A field experiment was conducted at an open-pit mine spoil heap in a semi-arid grassland area in eastern my country. A borehole 100 cm deep and 10 cm in diameter was drilled within the spoil heap, preserving the complete structure of the excavated soil sample. A plastic hose with a diameter of 3 cm and a length greater than the borehole depth was lowered to the bottom of the borehole with a weight attached to one end. The other end of the hose was then tightened slightly at the borehole. 20 L of hydrogen-oxygen isotope liquid was injected through the hose, and the excavated soil sample was backfilled into the borehole.

[0050] At the third and sixth months after the injection of tracer solution, 100cm soil columns with a diameter of 5cm were drilled at the same location in the spoil heap using a drilling machine. Soil samples were obtained at depths of 5cm, 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, and 100cm corresponding to the soil columns. The samples were quickly placed into 250mL plastic bottles, sealed with sealing film, and stored in a refrigerated box. The samples were then brought back to the laboratory as soon as possible for hydrogen and oxygen isotope analysis. The selected surface plants were the herbaceous plant *Alternanthera philoxeroides* and the shrubs *Caragana korshinskii* and *Caragana microphylla*. The plants were manually dug up to preserve their complete root systems and stems and leaves. They were then sealed in sealing bags and stored in a refrigerated box for hydrogen and oxygen isotope analysis.

[0051] The results showed that after three months, soil water replenished by groundwater could migrate vertically upwards by 50 cm, and after six months, it could continue to migrate vertically upwards until reaching the surface. This demonstrates that the in-situ hydrogen and oxygen isotope tracing experiment has a good labeling effect on soil water evaporation and transpiration.

[0052] Example 2

[0053] A field experiment was conducted at an open-pit mine spoil heap in a semi-arid grassland area in eastern my country. Holes with depths of 20cm, 30cm, 50cm, 70cm, 100cm, 200cm, and 300cm, and a diameter of 10cm, were drilled within the spoil heap. The complete structure of the drilled soil samples was preserved. A plastic hose with a diameter of 3cm and a length exceeding the borehole depth was lowered to the bottom of the borehole with a weight attached to one end. The other end was held taut at the borehole. 20L of hydrogen-oxygen isotope liquid was injected through the hose, and the drilled soil samples were then backfilled into the borehole. The observation period was 6 months.

[0054] Six months later, soil columns with a diameter of 5 cm were drilled at the same location in the spoil heap using a drilling machine. Soil samples were taken at 10 cm intervals at the corresponding soil layer depths of the soil columns, quickly placed into 250 mL plastic bottles, sealed with sealing film, and placed in a refrigerated box. The samples were then brought back to the laboratory as soon as possible for hydrogen and oxygen isotope determination and analysis in the soil. The selected surface plants were the herbaceous plant Alternanthera philoxeroides and the shrubs Caragana korshinskii and Caragana microphylla. The plants were manually dug up to preserve their complete root systems and stems and leaves, sealed in sealing bags, and placed in a refrigerated box for hydrogen and oxygen isotope determination and analysis.

[0055] By analyzing the migration and distribution characteristics of hydrogen and oxygen isotopes in soil and plants, the depth threshold for groundwater recharge from evaporation was calculated. Based on soil characteristics, the height of the soil capillary saturation zone was measured in the laboratory. The results showed that the height of the soil capillary saturation zone above the groundwater level in this area was h3 = 1.8 m; the water absorption depth of plant roots was h1 = 2.3 m; and the water isotope rise height shown in the hydrogen and oxygen isotope tracing experiment was h2 = 1.7 m. Therefore, the experimentally obtained depth threshold for groundwater recharge from evaporation was h = h1 + h2 + h3 = 5.8 m.

[0056] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for studying the situation of soil water and surface vegetation replenished by phreatic water evaporation, comprising the following steps: (1) demarcating a test area in a site to be tested, and sampling and measuring the hydrogen and oxygen isotope background values of soil layers at a target depth and each designed depth and the surface vegetation; (2) injecting hydrogen and oxygen isotope tracer liquid into a soil layer at the target depth to simulate a phreatic surface under the target depth, and setting an observation period; (3) after the observation period, sampling soil samples from each designed depth in the vertical direction between the injection site of the hydrogen and oxygen isotope tracer liquid and the surface, measuring the hydrogen and oxygen isotopes of the soil samples and the vegetation at the corresponding surface position of the injection site of the hydrogen and oxygen isotope tracer liquid to obtain hydrogen and oxygen isotope measurement values, combining the hydrogen and oxygen isotope background values obtained in step (1), and analyzing to obtain the situation of soil water and surface vegetation replenished by phreatic water evaporation at the target depth; the situation of soil water and surface vegetation replenished by phreatic water evaporation at the target depth comprises: a depth threshold of soil water replenished by phreatic water evaporation at the target depth, the utilization of the surface vegetation to the phreatic water at the target depth, and the migration rule of the soil water replenished by phreatic water evaporation in the soil layer; in the case of no vegetation growth on the surface, the height of the soil water replenished by phreatic water evaporation in the soil layer plus the height of the soil capillary saturation zone above the phreatic surface in the test area is the depth threshold of the soil water replenished by phreatic water evaporation; in the case of vegetation growth on the surface, the sum of the height of the water isotope rise shown by the hydrogen and oxygen isotope tracer test, the height of the soil capillary saturation zone above the phreatic surface in the test area, and the root water absorption depth of the surface vegetation is the depth threshold of the soil water replenished by phreatic water evaporation; the amount of the hydrogen and oxygen isotope tracer liquid injected into the soil layer at the target depth is not less than 1L. The amount of the hydrogen and oxygen isotope tracer liquid injected into the soil layer at the target depth is 1-1.5L. The soil samples are obtained by sampling in the hydrogen and oxygen isotope tracer liquid injection site and each designed depth soil layer in the vertical direction between the hydrogen and oxygen isotope tracer liquid injection site and the surface, and the hydrogen and oxygen isotope measurement values are obtained by measuring the soil samples, combining the hydrogen and oxygen isotope background values of the soil layers obtained in step (1), and analyzing to obtain the rise height of the soil water labeled by hydrogen and oxygen isotopes, so as to determine the depth threshold of the soil water replenished by phreatic water evaporation at the target depth and / or analyze the migration rule of the soil water replenished by phreatic water evaporation in the soil layer; and / or, the utilization of the surface vegetation to the phreatic water at the target depth is analyzed by analyzing the distribution characteristics of the surface vegetation roots in the soil, measuring the hydrogen and oxygen isotope measurement values of the vegetation at the corresponding surface position of the hydrogen and oxygen isotope tracer liquid injection site, and combining the hydrogen and oxygen isotope background values of the surface vegetation obtained in step (1). The target depth is 30cm-10m. For soil without plant growth, the target depth is 50cm-10m; for soil with plant growth, the target depth is 100cm-10m. The target depth is 2-5m. The designed depth is less than the target depth, and the depth of each corresponding soil layer is at least 5cm apart from the surface, and the number of the designed depths is at least 3. The interval is ≥10cm. The observation period is 24h-12 months. ​ ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein, ​ 3. The method according to claim 1 or 2, characterized in that, ​ ​ 4. The method of claim 3, wherein, ​ 5. The method of claim 4, wherein, ​ 6. The method of claim 4, wherein, ​ 7. The method according to claim 1 or 2, characterized in that, ​ 8. The method of claim 7, wherein, ​ 9. The method of claim 1 or 2, wherein, ​ 10. The method of claim 9, wherein, The observation period is 1-9 months.

11. The method of claim 10, wherein, The observation period is 3-6 months.

12. The method of claim 11, wherein, The observation period is 3-6 months in the dry season with little rain.

13. The method of claim 1 or 2, wherein, The injection of the hydrogen and oxygen isotope tracer into the target soil layer is achieved by a method comprising the following steps: Drilling a hole with the same depth as the target depth and keeping the structure of the drilled soil sample intact; one end of a plastic hose with a length greater than or equal to the target depth is tied with a weight and lowered into the bottom of the hole, and the hydrogen and oxygen isotope tracer is injected into the soil layer at the target depth through the plastic hose, and then the drilled soil sample is quickly backfilled into the hole.

14. The method of claim 13, wherein, The diameter of the hole is 8-12 cm.

15. The method of claim 1 or 2, wherein, In step (1) and step (3), the soil column is obtained by drilling a sampling hole with the same depth as the target depth and keeping the structure of the drilled soil sample intact, and the soil samples are obtained by sampling at the corresponding design depths of the soil column to determine the hydrogen and oxygen isotope background values and / or hydrogen and oxygen isotope determination values.

16. The method of claim 15, wherein, The diameter of the sampling hole is 4-6 cm.

17. The method of claim 1 or 2, wherein, The surface vegetation is at least one of herbaceous plants and shrub plants.

18. The method of claim 17, wherein, The surface vegetation is at least one of Caragana, shrub plant, and small leaf ornamental bird.

19. Use of the method of any one of claims 1-18 in studying the evaporation of groundwater in a semi-arid grassland open-pit mine area and the supply of soil water and surface vegetation.

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