Identification and characterization method of groundwater flow system based on stratified pumping test

Abstract

The present invention relates to a method for identifying and characterizing a groundwater flow system based on a stratified pumping test, comprising: obtaining a typical profile of a survey area; obtaining stratified pumping test data of at least two levels of groundwater flow systems based on distribution information of the groundwater flow system in the typical profile; identifying the groundwater flow system boundary based on water level data and groundwater age data in the stratified pumping test data, and verifying the identification result based on water quality data in the stratified pumping test data to obtain the groundwater flow system boundary; using the water level data and groundwater age data as constraints, establishing a 2D groundwater flow and solute transport numerical model of the profile to simulate the distribution of groundwater flow and groundwater age, and characterizing the circulation characteristics of the groundwater flow system based on the simulation results and the groundwater flow system boundary. The present invention improves the accuracy of identifying the vertical boundary of the groundwater flow system and improves the accuracy of characterizing the circulation characteristics of the groundwater flow system.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater flow system identification and characterization, and in particular to a groundwater flow system identification and characterization method based on a stratified pumping test. Background Art

[0002] Groundwater flow systems reveal a multi-level, nested pattern of local, intermediate, and regional groundwater flows. The study of groundwater flow systems is widely used in many research and application fields, including groundwater utilization and protection, petroleum exploration, geoenvironmental engineering, and waste geological disposal. Therefore, the identification and characterization of groundwater flow systems is a powerful tool for accurately understanding regional groundwater flow and circulation patterns.

[0003] Currently, methods for identifying and characterizing groundwater flow systems, as a key component of theoretical research on groundwater flow systems, have been extensively studied through numerical simulations and laboratory experiments. However, traditional hydrogeological surveys, whether for phreatic or confined water, emphasize the flow of water along the layers (two-dimensional planes). A lack of vertically layered data on the three-dimensional structure of groundwater flow results in insufficient information on the hydrodynamic characteristics of the groundwater flow system's translaminar structure, making it difficult to accurately identify and characterize the structure of groundwater flow systems. Furthermore, existing data rarely demonstrate successful identification from field observations and experiments, limiting our understanding of regional groundwater circulation patterns under practical conditions. Summary of the Invention

[0004] (1) Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for identifying and characterizing groundwater flow systems based on stratified pumping tests, which solves the technical problems that the vertical boundaries of groundwater flow systems are difficult to accurately identify and divide, and the flow circulation characteristics of different groundwater flow systems are difficult to finely characterize.

[0006] (2) Technical solution

[0007] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0008] An embodiment of the present invention provides a method for identifying and characterizing a groundwater flow system based on a stratified pumping test, comprising:

[0009] S100, obtaining a typical profile of the survey area based on groundwater flow field information within the survey area;

[0010] S200, based on the distribution information of the groundwater flow system in the typical profile, obtaining layered pumping test data of at least two levels of the groundwater flow system;

[0011] S300, identifying the groundwater flow system boundary in the typical profile based on the water level data and groundwater age data in the stratified pumping test data, and verifying the identification result based on the water quality data in the stratified pumping test data to obtain the groundwater flow system boundary;

[0012] S400. Using the water level data and the groundwater age data as constraints, a numerical model of two-dimensional groundwater flow and solute transport in a profile is established to simulate the distribution of groundwater flow and groundwater age in a typical profile, and the circulation characteristics of the groundwater flow system in the typical profile are characterized based on the simulation results and the boundary of the groundwater flow system.

[0013] Optionally, the cross-sectional direction of the typical cross-section is along the groundwater flow direction, and the groundwater flow system traversed by the typical cross-section includes a regional groundwater flow system, an intermediate groundwater flow system and a local groundwater flow system.

[0014] Optionally, step S200 includes:

[0015] S210, based on the distribution information of the groundwater flow system in the typical profile, determining the location of the hydrogeological borehole for performing the stratified pumping test in the discharge area of ​​at least two levels of the groundwater flow system;

[0016] S220, obtaining the number of pumping layers for performing a stratified pumping test based on the information on the number of aquifers in the discharge area of ​​the groundwater flow system;

[0017] S230. Control the double packer system installed on the hydrogeological borehole to perform a stratified pumping test according to the number of pumping layers, and obtain stratified pumping test data including permeability coefficients of aquifers at different depths, groundwater level data, water quality data, and groundwater age data.

[0018] Optionally, step S230 includes:

[0019] S231, controlling the double packer system to form a pumping test section at each pumping layer, wherein the water level data of the pumping test section is the groundwater level data of the aquifer to which the pumping layer belongs;

[0020] S232. According to the steady flow pumping test method, obtain the permeability coefficient of the aquifer to which each pumping layer belongs;

[0021] S233, testing the groundwater quality in each pumping test section to obtain water quality data including groundwater hydrochemistry, stable isotopes, and radioactive isotopes;

[0022] S234. Determine the groundwater recharge source and path of the aquifer to which each pumping layer belongs based on the groundwater hydrochemistry and stable isotope composition information;

[0023] S235. Based on the radioactive isotope and in combination with the radioactive isotope half-life calculation formula, the groundwater age data of the aquifer to which each pumping layer belongs is obtained.

[0024] Optionally, step S300 includes:

[0025] S310, obtaining a groundwater head inflection point of a groundwater flow system based on the water level data in the stratified pumping test data;

[0026] S320, based on the groundwater age data in the stratified pumping test data, obtaining a groundwater age mutation point of the groundwater flow system; and comparing the position of the groundwater age mutation point with the position of the groundwater head inflection point, and determining the initial groundwater flow system boundary based on the comparison result;

[0027] S330. Verify the initial groundwater flow system boundary based on the water quality data in the stratified pumping test data to obtain the groundwater flow system boundary.

[0028] Optionally, step S310 includes:

[0029] S311, judging the flow trend of groundwater based on the water level data in the stratified pumping test data;

[0030] S312a, if the water level of the lower groundwater layer is higher than that of the upper groundwater layer, it is determined that the flow trend of the groundwater is an upward flow trend;

[0031] S312b, if the water level of the lower groundwater layer is lower than that of the upper groundwater layer, it is determined that the flow trend of the groundwater is a downward flow trend;

[0032] S313. Based on the determination result of the groundwater flow trend, determine the location point where the flow trend changes as the groundwater head inflection point of the groundwater flow system.

[0033] Optionally, step S320 includes:

[0034] S321, obtaining the groundwater age change gradient of adjacent layers based on the groundwater age data and the number of pumping layers in the stratified pumping test data;

[0035] S322. Based on the groundwater age variation gradients at different layers, calculate the average groundwater age gradient of the groundwater flow system;

[0036] S323, comparing each groundwater age change gradient with the groundwater age average gradient;

[0037] S324. When the comparison result shows that the groundwater age change gradient is greater than the groundwater age average gradient, determining whether the position of the comparison result coincides with the position of the groundwater head inflection point;

[0038] S325: If the position to which the comparison result belongs coincides with the position of the groundwater head inflection point, the position is determined to be the boundary of the initial groundwater flow system.

[0039] Optionally, step S400 includes:

[0040] S410, establishing a groundwater flow conceptual model of the typical section by generalizing the aquifer structure, aquifer parameters, boundary conditions, and source and sink terms of the groundwater flow system in the typical section;

[0041] S420: Based on the groundwater flow conceptual model, using the water level data and the groundwater age data as constraints, establish a numerical model of cross-sectional two-dimensional groundwater flow and solute transport;

[0042] S430, numerical model of two-dimensional groundwater flow and solute transport in control profile simulates the distribution of groundwater flow and groundwater age in a typical profile, and obtains the distribution results of groundwater flow and groundwater age in the typical profile;

[0043] S440. Using the circulation depth, circulation volume and age distribution range as indicators, based on the distribution results of groundwater flow and groundwater age in the typical profile, the groundwater flow system boundary is used to characterize the circulation characteristics of the groundwater flow system in the typical profile.

[0044] Optionally, step S410 includes:

[0045] S411. Generalizing the aquifer structure of the groundwater flow system in the typical profile includes: generalizing the aquifer in the typical profile into a homogeneous anisotropic aquifer based on the type, lithology, and thickness of the aquifer in the survey area;

[0046] S412. Generalize the aquifer parameters of the groundwater flow system in the typical section, wherein the aquifer parameters include permeability, porosity, and anisotropy;

[0047] S413, generalizing the boundary conditions and source-sink terms of the groundwater flow system in the typical section includes: generalizing the bottom boundary of the typical section as a water-retaining boundary, generalizing the side boundaries of the typical section as a zero-flow boundary, and generalizing the upper boundary of the typical section as a constant-head boundary;

[0048] S414. Based on the generalized results of aquifer structure, aquifer parameters, boundary conditions and source and sink terms in the groundwater flow system, a conceptual groundwater flow model of a typical profile is established.

[0049] Optionally, step S420 includes:

[0050] S421. Based on the conceptual model of groundwater flow in a typical section, establish a two-dimensional groundwater flow numerical model and a solute transport numerical model for the section;

[0051] S422, controlling the cross-section two-dimensional groundwater flow numerical model to perform groundwater flow simulation using the water level data as a constraint condition, and correcting the aquifer anisotropy parameters in the cross-section two-dimensional groundwater flow numerical model according to the groundwater flow simulation results;

[0052] S423. The solute transport numerical model is controlled to perform groundwater age simulation using the groundwater age data as a constraint condition, and the model parameters in the solute transport numerical model are modified according to the groundwater age simulation result.

[0053] (3) Beneficial effects

[0054] The beneficial effects of the present invention are as follows: the present invention proposes a method for identifying and characterizing groundwater flow systems based on stratified pumping tests. Since the vertical stratified measured data of the stratified pumping tests are used to identify the boundaries of different types of groundwater flow systems, and the water quality data of different aquifers are combined to verify the boundaries of the groundwater flow systems, compared with the existing technology, the accuracy of groundwater flow system identification is greatly improved.

[0055] At the same time, the present invention improves the two-dimensional simulation results of the groundwater flow system profile by selecting typical profiles and carrying out two-dimensional simulation of the groundwater flow system profile with vertically layered groundwater level data and groundwater age data as constraints, thereby improving the accuracy of the groundwater flow system structure characterization.

[0056] In addition, the present invention realizes the boundary division and characteristic characterization of groundwater flow systems of different types and depths, which can quantitatively reveal and finely characterize the groundwater circulation laws to provide key parameters, and provide key data for the stratified evaluation of groundwater resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic flow chart of a method for identifying and characterizing a groundwater flow system based on a stratified pumping test according to an embodiment of the present invention;

[0058] Figure 2 A typical cross-sectional view of a survey area provided in one embodiment of the present invention;

[0059] Figure 3 A schematic structural diagram of a dual packer system provided by one embodiment of the present invention;

[0060] Figure 4A groundwater flow trend diagram provided by an embodiment of the present invention;

[0061] Figure 5 A cross-sectional diagram including groundwater head, age, and water chemistry provided for one embodiment of the present invention;

[0062] Figure 6 A generalized schematic diagram of a typical cross section provided for an embodiment of the present invention;

[0063] Figure 7 A comparison chart of the measured results (scatter points) and numerical simulation results (curve) of the groundwater age profile provided in one embodiment of the present invention;

[0064] Figure 8 A two-dimensional model diagram of the layered pumping test data and numerical simulation results in a typical section provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0065] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0066] The embodiment of the present invention proposes.

[0067] refer to Figure 1 As shown, an embodiment of the present invention proposes a method for identifying and characterizing a groundwater flow system based on a stratified pumping test. The execution subject of the method of this embodiment may be a groundwater flow system identification device, which is electrically connected to a dual packer system and a database storing groundwater field information in a related area. The method may include:

[0068] S100: Obtain a typical profile of the survey area based on groundwater flow field information in the survey area.

[0069] S200. Based on the distribution information of the groundwater flow system in the typical profile, obtain layered pumping test data of at least two levels of the groundwater flow system.

[0070] S300, identifying the groundwater flow system boundary in the typical profile based on the water level data and groundwater age data in the stratified pumping test data, and verifying the identification result based on the water quality data in the stratified pumping test data to obtain the groundwater flow system boundary.

[0071] S400. Using water level data and groundwater age data as constraints, a numerical model of two-dimensional groundwater flow and solute transport in a profile is established to simulate the distribution of groundwater flow and groundwater age in a typical profile. The circulation characteristics of the groundwater flow system in a typical profile are characterized based on the simulation results and the boundaries of the groundwater flow system.

[0072] In this embodiment, the technical solution of using the vertical stratified measured data of the stratified pumping test to identify the boundaries of different types of groundwater flow systems and combining the water quality data of different aquifers to verify the boundaries of the groundwater flow systems greatly improves the accuracy of groundwater flow system identification compared to the existing technology.

[0073] At the same time, this embodiment improves the two-dimensional simulation results of the groundwater flow system profile by selecting typical profiles and conducting two-dimensional simulation of the groundwater flow system profile with vertically layered groundwater level data and groundwater age data as constraints, thereby improving the accuracy of the groundwater flow system structure characterization.

[0074] In addition, this embodiment realizes the boundary division and characteristic characterization of groundwater flow systems of different types and depths, which can quantitatively reveal and finely characterize the groundwater circulation laws to provide key parameters, and provide key data for the stratified evaluation of groundwater resources.

[0075] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0076] Specifically, refer to Figure 1 As shown, an embodiment of the present invention provides a method for identifying and characterizing a groundwater flow system based on a stratified pumping test, which includes:

[0077] S100: Obtain a typical profile of the survey area based on groundwater flow field information in the survey area.

[0078] For example, if Figure 2 As shown in the figure, first, a certain area in the Ordos Plateau is selected as the exploration area. Then, based on the selected exploration area, a two-dimensional map of the groundwater flow field information of the exploration area is retrieved from the database. Finally, according to the groundwater flow direction and the recharge area, runoff area, and discharge area of ​​the groundwater flow system of different levels in the two-dimensional map, the position line (point A to point B) of the typical section is selected. Among them, the cross-sectional direction of the typical section is along the groundwater flow direction, and the groundwater flow system traversed by the typical section includes the regional groundwater flow system, the intermediate groundwater flow system, and the local groundwater flow system.

[0079] S200. Based on the distribution information of the groundwater flow system in the typical profile, obtain stratified pumping test data of at least two levels of the groundwater flow system. In this embodiment, local groundwater flow systems and regional groundwater flow systems are used as examples for illustration. In practice, in order to better obtain the vertical stratified measured data of the groundwater flow system, the location of the hydrogeological borehole for performing the stratified pumping test can be selected as the groundwater flow system discharge area, and the drilling depth of the hydrogeological borehole can be determined based on the thickness of the aquifer in the survey area or the survey depth. The vertical stratified measured data here may include stratified pumping test data such as the permeability coefficient of aquifers at different depths, groundwater level data, water quality data, and groundwater age data.

[0080] For example, step S200 in this embodiment may include the following sub-steps S210 to S230:

[0081] S210. Based on the distribution information of the groundwater flow system in the typical profile, determine the locations of the hydrogeological boreholes for performing the stratified pumping test in the discharge areas of at least two levels of groundwater flow systems.

[0082] In this embodiment, stratified pumping tests are performed in two levels of groundwater flow systems, namely the local groundwater flow system and the regional groundwater flow system, and the location of the hydrogeological borehole for performing the stratified pumping test is selected in the discharge area of ​​the groundwater flow system, so as to obtain more accurate stratified pumping test data for the groundwater flow system.

[0083] S220: Obtain the number of pumping layers for performing a stratified pumping test based on the number of aquifers in the discharge area of ​​the groundwater flow system, wherein the number of pumping layers is configured to be at least three.

[0084] S230. Control the double packer system installed on the hydrogeological borehole to perform a stratified pumping test according to the number of pumping layers, and obtain stratified pumping test data including permeability coefficients of aquifers at different depths, groundwater level data, water quality data, and groundwater age data.

[0085] Furthermore, step S230 includes:

[0086] S231. Control the double packer system to form a pumping test section at each pumping layer. The water level data of the pumping test section is the groundwater level data of the aquifer to which the pumping layer belongs.

[0087] For example, Figure 3As shown in the figure, when the upper packer and the lower packer in the double packer system move to the corresponding pumping layer, the upper packer and the lower packer are controlled to inflate to form three water level change sections, namely the first water level change section in the upper part of the upper packer, the second water level change section (pumping test section) between the upper packer and the lower packer, and the third water level change section in the lower part of the lower packer; when the three water level change sections are stable, the water level data of the second water level change section (pumping test section) is taken as the groundwater level data of the aquifer to which the pumping layer belongs.

[0088] S232. According to the steady flow pumping test method, obtain the permeability coefficient of the aquifer to which each pumping layer belongs.

[0089] Specifically, the following formula (1) is used to obtain the permeability coefficient of the aquifer to which each pumping layer belongs.

[0090]

[0091] Among them, K is the permeability coefficient of the aquifer to which the pumping layer belongs, Q is the pumping flow rate, S is the water level drawdown, M is the length of the pumping test section, R is the impact radius, and r is the wellbore radius of the hydrogeological borehole.

[0092] S233. Conduct water quality testing on the groundwater in each pumping test section to obtain water quality data including groundwater hydrochemistry, stable isotopes and radioisotopes. Groundwater hydrochemistry includes Cl - 、TDS、Sr 2+ 、TDS / Cl - 、HCO3 - / Cl and SO4 2- / HCO3 - Parameters such as stable isotopes include 2 H. 18 O. 13 C and 34 S, etc. Radioactive isotopes include: 3 H. 40 Ar, 14 C. 4 He, 81 Kr and 36 Cl et al.

[0093] S234. Based on the groundwater hydrochemistry and stable isotope composition information, determine the groundwater recharge source and path of the aquifer to which each pumping layer belongs.

[0094] S235. Based on radioactive isotopes and the calculation formula of radioactive isotope half-life, the groundwater age data of the aquifer to which each pumping layer belongs is obtained.

[0095] For example, using 3 H can identify the age of modern groundwater from 0 to 70 years (since the nuclear explosion); 40 Ar can identify the age of groundwater ranging from hundreds to thousands of years; 14 C can identify the age of groundwater within 40,000 years; 4 He, 81 Kr and 36 The comprehensive analysis of three radioactive isotopes of Cl and the hydrogeological conditions of the region can identify a groundwater age of more than 40,000 years.

[0096] S300, identifying the groundwater flow system boundary in the typical profile based on the water level data and groundwater age data in the stratified pumping test data, and verifying the identification result based on the water quality data in the stratified pumping test data to obtain the groundwater flow system boundary.

[0097] For example, step S300 in this embodiment may include the following sub-steps S310 to S330:

[0098] S310, based on the water level data in the stratified pumping test data, obtain the groundwater head inflection point of the groundwater flow system. In this embodiment, the groundwater head inflection point is determined based on the trend of water level elevation (water head) changing with depth: the position where the water level elevation trend changes, that is, the position where the water level elevation changes from increasing with depth to decreasing with depth (reference Figure 4 ), or the point where the water level changes from decreasing with depth to increasing with depth.

[0099] Furthermore, step S310 includes:

[0100] S311. Determine the flow trend of groundwater based on the water level data in the stratified pumping test data.

[0101] S312a. If the water level of the lower groundwater is higher than that of the upper groundwater, it is determined that the flow trend of the groundwater is an upward flow trend.

[0102] S312b. If the water level of the lower groundwater layer is lower than that of the upper groundwater layer, it is determined that the flow trend of the groundwater is a downward flow trend.

[0103] S313. Based on the determination result of the groundwater flow trend, determine the location point where the flow trend changes as the groundwater head inflection point of the groundwater flow system.

[0104] S320. Based on the groundwater age data in the stratified pumping test data, obtain the groundwater age mutation point of the groundwater flow system; and compare the position of the groundwater age mutation point with the position of the groundwater head inflection point, and determine the initial groundwater flow system boundary based on the comparison result.

[0105] Furthermore, step S320 includes:

[0106] S321. Based on the groundwater age data and the number of pumping layers in the stratified pumping test data, calculate the groundwater age change gradient of adjacent layers.

[0107] Specifically, the following formula (2) is used to obtain the groundwater age change gradient to the adjacent layers.

[0108] I=ΔT / Δd (2)

[0109] Where I is the groundwater age gradient of adjacent horizons, ΔT is the depth of the adjacent horizon, and Δd is the difference in groundwater age between adjacent horizons.

[0110] S322. Based on the groundwater age variation gradients at different layers, calculate the average groundwater age gradient of the groundwater flow system. The average groundwater age gradient is the arithmetic mean of the underground age gradients at different layers.

[0111] S323. Compare each groundwater age change gradient with the average groundwater age gradient to determine the groundwater age mutation point, i.e., the location where the groundwater age change gradient is greater than the average groundwater age gradient.

[0112] S324. When the comparison result shows that the groundwater age change gradient is greater than the groundwater age average gradient, determine whether the position to which the comparison result belongs coincides with the position of the groundwater head inflection point.

[0113] S325. If the position to which the comparison result belongs coincides with the position of the groundwater head inflection point, it is determined that the position is the initial groundwater flow system boundary.

[0114] S330. Verify the initial groundwater flow system boundary based on the water quality data in the stratified pumping test data to obtain the groundwater flow system boundary.

[0115] For example, based on the hydrochemical data of water quality data in aquifers at different depths, hydrochemical profiles of various hydrochemical indicators varying with depth are drawn and compared with the hydraulic head and groundwater age profiles, e.g. Figure 5 As shown in the figure, the green strips represent the boundaries of the groundwater flow system. Specifically, the water chemical indicators selected include Cl - 、TDS、Sr 2+ 、TDS / Cl -、HCO3 - / Cl and SO4 2- / HCO3 - et al., Cl - , TDS and Sr 2+ Used to characterize and identify differences in groundwater transport distances in different groundwater flow systems, TDS / Cl - 、HCO3 - / Cl and SO4 2- / HCO3 - Used to characterize and identify differences in groundwater residence time and potential impacts of water-rock interactions on hydrochemical characteristics.

[0116] S400. Using water level data and groundwater age data as constraints, a numerical model of two-dimensional groundwater flow and solute transport in a profile is established to simulate the distribution of groundwater flow and groundwater age in a typical profile. The circulation characteristics of the groundwater flow system in a typical profile are characterized based on the simulation results and the boundaries of the groundwater flow system.

[0117] For example, step S400 in this embodiment may include the following sub-steps S410 to S440:

[0118] S410. Establish a conceptual groundwater flow model for a typical section by generalizing the aquifer structure, aquifer parameters, boundary conditions, and source and sink terms of the groundwater flow system in the typical section.

[0119] Furthermore, step S410 includes:

[0120] S411. Generalizing the aquifer structure of the groundwater flow system in a typical profile includes: generalizing the aquifer in the typical profile into a homogeneous anisotropic aquifer based on the type, lithology and thickness of the aquifer in the survey area.

[0121] In this embodiment, the strata in the typical profile are Jurassic, Cretaceous and Quaternary strata from bottom to top. The Jurassic strata in the lower part of the typical profile have less pores and fissures, poor permeability, and a permeability coefficient of less than 0.005m / d. The Jurassic strata can be generalized as an aquifer. The surface layer of the typical profile is mostly covered by Quaternary aeolian sand or exposed Cretaceous weathered sandstone. A small part of the surface layer of the lake basin beach is Quaternary lake deposits. The thickness of the Quaternary strata on the profile is relatively small, and most of it is permeable and does not contain water, which has little impact on the groundwater flow field. Therefore, the Quaternary strata and the Cretaceous strata are generalized into a unified homogeneous anisotropic aquifer, wherein the thickness of the homogeneous anisotropic aquifer is 700m based on the thickness of the Quaternary strata and the Cretaceous strata.

[0122] S412. Generalize the aquifer parameters of the groundwater flow system in a typical profile. Aquifer parameters include permeability, porosity, and anisotropy.

[0123] In this example, the generalized permeability coefficient is assigned based on the permeability coefficient values ​​from the stratified pumping test data. The permeability coefficient is the average permeability coefficient of each stratified pumping test data, i.e., 0.3 m / d. Aquifer anisotropy is represented by the ratio of the horizontal permeability coefficient to the vertical permeability coefficient (Kh / Kv).

[0124] S413. Generalizing the boundary conditions and source-sink items of the groundwater flow system in the typical section includes: generalizing the bottom boundary of the typical section to a water-retaining boundary, generalizing the side boundaries of the typical section to a zero-flow boundary, and generalizing the upper boundary of the typical section to a constant-head boundary.

[0125] In this embodiment, the bottom boundary of the typical profile is the Jurassic aquiclude, which can be generalized as an aquiclude boundary; the left boundary of the typical profile is the regional groundwater watershed, and the right boundary is the regional discharge base level, so the boundaries on both sides of the typical profile are generalized as zero flow boundaries; the upper boundary of the typical profile is the groundwater surface, which is recharged by atmospheric precipitation. The regional groundwater level is controlled by the topography, so it is generalized as a constant head boundary.

[0126] S414. Based on the generalized results of aquifer structure, aquifer parameters, boundary conditions and source and sink terms in the groundwater flow system, a conceptual groundwater flow model of a typical profile is established.

[0127] In this embodiment, a typical profile is formed based on a certain exploration area in the Ordos Plateau. The aquifer structure, aquifer parameters, boundary conditions, and source and sink items of the groundwater flow system in the typical profile are generalized in steps S411 to S413. Finally, the following generalization steps are established based on the generalization results: Figure 6 Conceptual model of groundwater flow for a typical section shown.

[0128] S420. Based on the conceptual model of groundwater flow, a cross-sectional two-dimensional groundwater flow numerical model is established with water level data and groundwater age data as constraints.

[0129] Furthermore, step S420 includes:

[0130] S421. Based on the conceptual model of groundwater flow in a typical profile, a two-dimensional groundwater flow numerical model and a solute transport numerical model are established.

[0131] In this embodiment, the cross-sectional two-dimensional groundwater flow numerical model is represented by the following differential equation problem:

[0132]

[0133] Among them, K x is the vertical permeability coefficient, K zis the vertical permeability coefficient, h is the groundwater head (water level), Ω is the seepage area of ​​the typical section, h1 is the hydraulic head on the hydraulic head boundary, and Γ1 is the hydraulic head boundary.

[0134] S422. The control section two-dimensional groundwater flow numerical model simulates groundwater flow using water level data as a constraint condition, and modifies the aquifer anisotropy parameters in the section two-dimensional groundwater flow numerical model based on the groundwater flow simulation results.

[0135] In this embodiment, the cross-sectional two-dimensional groundwater flow numerical model uses the water level data in the stratified pumping test data as a constraint condition to carry out groundwater flow simulation, fits and compares the groundwater flow simulation results with the groundwater head observation results, and then determines the anisotropic parameters of the aquifer of the cross-sectional two-dimensional groundwater flow numerical model through experimental parameter adjustment.

[0136] S423. The solute transport numerical model is controlled to simulate the groundwater age using the groundwater age data as a constraint condition, and the model parameters in the solute transport numerical model are modified according to the groundwater age simulation results.

[0137] In this example, the solute transport numerical model uses the groundwater age data from the stratified pumping test data as a constraint to simulate the migration and decay of radioactive isotopes in groundwater. The concentration is then converted into groundwater age according to the isotope half-life formula to obtain a steady-state distribution of groundwater age. The simulated groundwater age results are then fitted and compared with the measured groundwater age results. The model parameters in the solute transport numerical model are then determined through experimental parameter adjustment. These model parameters include effective porosity, longitudinal diffusivity, the ratio of lateral diffusivity to longitudinal diffusivity, and the effective molecular diffusion coefficient.

[0138] In a specific embodiment, a solute transport numerical model is established using the MT3DMS module (Modular Three-dimensional Transport of Solutes in Groundwater Systems) on the GMS (Groundwater Modeling System). Next, the migration and decay processes of radioactive isotopes in groundwater are simulated over a simulation period of 600 ka to obtain a steady-state distribution of groundwater age. The obtained steady-state distribution of groundwater age is then repeatedly fitted and compared with the measured ages of groundwater stratifications in hydrogeological boreholes, such as Figure 7As shown; finally, through experimental adjustment, the following model parameters in the numerical model of underground solute transport were determined: ratio of horizontal permeability to vertical permeability, Kh / Kv=500; effective porosity, ne=0.2; longitudinal diffusivity, L=10m; ratio of lateral diffusivity to longitudinal diffusivity, L / T=0.1; effective molecular diffusion coefficient, D0=0.06m2 / a.

[0139] S430. The numerical model of two-dimensional groundwater flow and solute transport in the control section simulates the distribution of groundwater flow and groundwater age in the typical section and obtains the distribution results of groundwater flow and groundwater age in the typical section.

[0140] It is worth mentioning that the groundwater flow path in a typical profile was determined based on the simulation results of the two-dimensional groundwater flow numerical model in the profile, combined with the particle tracing technology.

[0141] In the embodiment, particle tracing is performed using the MODPATH module on the GMS. First, the groundwater level, permeability coefficient and porosity on the typical profile of the simulation results of the two-dimensional groundwater flow numerical model of the profile are read; then, according to the horizontal and vertical groundwater flow velocities of each active node, tracer particles are placed on each node using the forward difference method; finally, the groundwater flow path in the typical profile is determined based on the movement trajectory of the tracer particles in the groundwater flow field.

[0142] S440. Using circulation depth, circulation volume and age distribution range as indicators, based on the distribution results of groundwater flow and groundwater age in typical profiles and the boundaries of the groundwater flow system, the circulation characteristics of the groundwater flow system in typical profiles are characterized.

[0143] In this embodiment, Figure 8 As shown in Table 1, the water level data and groundwater age data in the stratified pumping test data, the numerical simulation results of groundwater flow and age distribution in typical profiles, and the identified groundwater flow system boundaries are integrated to determine the circulation depth, circulation volume and age distribution range of the local groundwater flow system, intermediate groundwater flow system and regional groundwater flow system in the typical profile. The specific characteristics are shown in Table 1.

[0144] Table 1. Groundwater flow system characteristics

[0145]

[0146] In summary, the present invention provides a method for identifying and characterizing groundwater flow systems based on stratified pumping tests. Through the mutual verification and comprehensive judgment of multiple data evidence, the method achieves more accurate identification of groundwater flow systems. Utilizing detailed vertically stratified measured data, the multi-level nested structure of the flow system can be successfully identified. In particular, by combining measured data such as hydrodynamics, groundwater level, groundwater age, and hydrochemistry as key data for identifying groundwater flow system boundaries, the method significantly reduces uncertainty in groundwater flow system identification.

[0147] At the same time, the present invention selects typical profiles and comprehensively uses hydrogeological drilling, groundwater stratification pumping tests, and a variety of radioactive isotope combined dating techniques to obtain information such as stratified aquifer parameters, water level, water quality, age, isotopes, etc., and conducts two-dimensional simulation of groundwater flow system profiles under various constraints to achieve a detailed characterization of the groundwater flow system structure.

[0148] In addition, the present invention realizes the boundary division and characteristic characterization of groundwater flow systems at different levels and depths, which can provide key parameters for quantitatively revealing and finely characterizing the laws of groundwater circulation, and provide key data and basis for the stratified evaluation and utilization of groundwater resources. It can serve as a key technology for groundwater stratification exploration.

[0149] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0150] The present invention is described with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions.

[0151] It should be noted that, in the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention may be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In claims enumerating several means, several of these means may be embodied by one and the same hardware. The use of the words first, second, third etc. is for convenience only and does not indicate any order. These words may be understood as part of the component name.

[0152] In addition, it should be noted that, in the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0153] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments after learning the basic creative concept. Therefore, the claims should be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0154] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims and their equivalents, the present invention shall also include such modifications and variations.

Claims

1. A method for identifying and characterizing groundwater flow systems based on stratified pumping tests, characterized in that: include: S100, obtaining a typical profile of the survey area based on groundwater flow field information within the survey area; S200, based on the distribution information of the groundwater flow system in the typical profile, obtaining layered pumping test data of at least two levels of the groundwater flow system; S300, identifying the groundwater flow system boundary in the typical profile based on the water level data and groundwater age data in the stratified pumping test data, and verifying the identification result based on the water quality data in the stratified pumping test data to obtain the groundwater flow system boundary; S400. Using the water level data and the groundwater age data as constraints, a numerical model of two-dimensional groundwater flow and solute transport in a profile is established to simulate the distribution of groundwater flow and groundwater age in a typical profile, and the circulation characteristics of the groundwater flow system in the typical profile are characterized based on the simulation results and the boundary of the groundwater flow system.

2. The method according to claim 1, wherein The cross-sectional direction of the typical cross-section is along the groundwater flow direction, and the groundwater flow system traversed by the typical cross-section includes a regional groundwater flow system, an intermediate groundwater flow system and a local groundwater flow system.

3. The method according to claim 1, wherein The step S200 includes: S210, based on the distribution information of the groundwater flow system in the typical profile, determining the location of the hydrogeological borehole for performing the stratified pumping test in the discharge area of ​​at least two levels of the groundwater flow system; S220, obtaining the number of pumping layers for performing a stratified pumping test based on the information on the number of aquifers in the discharge area of ​​the groundwater flow system; S230. Control the double packer system installed on the hydrogeological borehole to perform a stratified pumping test according to the number of pumping layers, and obtain stratified pumping test data including permeability coefficients of aquifers at different depths, groundwater level data, water quality data, and groundwater age data.

4. The method according to claim 3, wherein The step S230 includes: S231, controlling the double packer system to form a pumping test section at each pumping layer, wherein the water level data of the pumping test section is the groundwater level data of the aquifer to which the pumping layer belongs; S232. According to the steady flow pumping test method, obtain the permeability coefficient of the aquifer to which each pumping layer belongs; S233, testing the groundwater quality in each pumping test section to obtain water quality data including groundwater hydrochemistry, stable isotopes, and radioactive isotopes; S234. Determine the groundwater recharge source and path of the aquifer to which each pumping layer belongs based on the groundwater hydrochemistry and stable isotope composition information; S235. Based on the radioactive isotope and in combination with the radioactive isotope half-life calculation formula, the groundwater age data of the aquifer to which each pumping layer belongs is obtained.

5. The method according to claim 1, wherein The step S300 includes: S310, obtaining a groundwater head inflection point of a groundwater flow system based on the water level data in the stratified pumping test data; S320, based on the groundwater age data in the stratified pumping test data, obtaining a groundwater age mutation point of the groundwater flow system; and comparing the position of the groundwater age mutation point with the position of the groundwater head inflection point, and determining the initial groundwater flow system boundary based on the comparison result; S330. Verify the initial groundwater flow system boundary based on the water quality data in the stratified pumping test data to obtain the groundwater flow system boundary.

6. The method according to claim 5, wherein The step S310 includes: S311, judging the flow trend of groundwater based on the water level data in the stratified pumping test data; S312a, if the water level of the lower groundwater layer is higher than that of the upper groundwater layer, it is determined that the flow trend of the groundwater is an upward flow trend; S312b, if the water level of the lower groundwater layer is lower than that of the upper groundwater layer, it is determined that the flow trend of the groundwater is a downward flow trend; S313. Based on the determination result of the groundwater flow trend, determine the location point where the flow trend changes as the groundwater head inflection point of the groundwater flow system.

7. The method according to claim 5, wherein The step S320 includes: S321, obtaining the groundwater age change gradient of adjacent layers based on the groundwater age data and the number of pumping layers in the stratified pumping test data; S322. Based on the groundwater age variation gradients at different layers, calculate the average groundwater age gradient of the groundwater flow system; S323, comparing each groundwater age change gradient with the groundwater age average gradient; S324. When the comparison result shows that the groundwater age change gradient is greater than the groundwater age average gradient, determining whether the position of the comparison result coincides with the position of the groundwater head inflection point; S325: If the position to which the comparison result belongs coincides with the position of the groundwater head inflection point, the position is determined to be the boundary of the initial groundwater flow system.

8. The method according to claim 1, wherein The step S400 includes: S410, establishing a groundwater flow conceptual model of the typical section by generalizing the aquifer structure, aquifer parameters, boundary conditions, and source and sink terms of the groundwater flow system in the typical section; S420: Based on the groundwater flow conceptual model, using the water level data and the groundwater age data as constraints, establish a numerical model of cross-sectional two-dimensional groundwater flow and solute transport; S430, numerical model of two-dimensional groundwater flow and solute transport in control profile simulates the distribution of groundwater flow and groundwater age in a typical profile, and obtains the distribution results of groundwater flow and groundwater age in the typical profile; S440. Using the circulation depth, circulation volume and age distribution range as indicators, based on the distribution results of groundwater flow and groundwater age in the typical profile, the groundwater flow system boundary is used to characterize the circulation characteristics of the groundwater flow system in the typical profile.

9. The method according to claim 8, wherein The step S410 includes: S411. Generalizing the aquifer structure of the groundwater flow system in the typical profile includes: generalizing the aquifer in the typical profile into a homogeneous anisotropic aquifer based on the type, lithology, and thickness of the aquifer in the survey area; S412. Generalize the aquifer parameters of the groundwater flow system in the typical section, wherein the aquifer parameters include permeability, porosity, and anisotropy; S413, generalizing the boundary conditions and source-sink terms of the groundwater flow system in the typical section includes: generalizing the bottom boundary of the typical section as a water-retaining boundary, generalizing the side boundaries of the typical section as a zero-flow boundary, and generalizing the upper boundary of the typical section as a constant-head boundary; S414. Based on the generalized results of aquifer structure, aquifer parameters, boundary conditions and source and sink terms in the groundwater flow system, a conceptual groundwater flow model of a typical profile is established.

10. The method according to claim 8, wherein The step S420 includes: S421. Based on the conceptual model of groundwater flow in a typical section, establish a two-dimensional groundwater flow numerical model and a solute transport numerical model for the section; S422, controlling the cross-section two-dimensional groundwater flow numerical model to perform groundwater flow simulation using the water level data as a constraint condition, and correcting the aquifer anisotropy parameters in the cross-section two-dimensional groundwater flow numerical model according to the groundwater flow simulation results; S423. The solute transport numerical model is controlled to perform groundwater age simulation using the groundwater age data as a constraint condition, and the model parameters in the solute transport numerical model are modified according to the groundwater age simulation result.

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