Coastal zone vadose zone and aquifer hydrogeological parameter estimation method and system

Abstract

The invention relates to a coastal zone vadose zone and aquifer hydrogeological parameter estimation method and system, and the method comprises the steps: building an underground water flow motion analysis model containing the influence of a vadose zone, and solving to obtain an analytic solution of the underground water level of an aquifer under tide driving; collecting drilling water level monitoring data of a to-be-estimated place, and analyzing a water level time sequence in the drilling water level monitoring data to obtain underground water level fluctuation; fitting the analytic solution of the underground water level with the underground water level fluctuation of the water level monitoring data, and selecting a parameter value corresponding to a fitting curve meeting the requirement; according to the method, on the basis of a Richards equation describing flowing of underground water in an aeration zone, an underground water flow mathematical model of the unsaturated-saturated coupled aquifer under tide driving is established, underground water level analytic solutions of different positions in the aeration zone and the aquifer are obtained through a mathematical analysis method and are matched with drilling observation data, and the underground water level analysis result is obtained. And the hydrogeological parameters of the vadose zone and the aquifer can be effectively inverted and estimated.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogeological parameter evaluation, and more specifically, to a method and system for estimating hydrogeological parameters of a coastal aeration zone and aquifer. Background Art

[0002] Accurate assessment of hydrogeological parameters in coastal zones is crucial for preventing and controlling seawater intrusion and formulating sustainable development plans for coastal zones. To obtain these parameters, hydrogeological parameter estimation methods based on groundwater level tidal response are widely used because they are economical, effective, and more in line with the natural hydrological environment of coastal zones. Compared with traditional pumping experiments, this method is based on long-term natural water level observation data for analysis and parameter inversion. It is not subject to human interference and can be monitored for a long time. Therefore, it has advantages in both economy and practicality. In addition, since ocean tides are common in coastal zones, the scope of application of this method is relatively wide.

[0003] However, existing studies on the tidal response of groundwater levels are usually limited to saturated aquifers, ignoring the unsaturated vadose zone that is ubiquitous in coastal areas. If the influence of the vadose zone is ignored, it will often lead to different degrees of deviation in parameter estimation, thus limiting the promotion and application of groundwater level tidal response methods. In order to solve the above problems, a method and system for estimating hydrogeological parameters of coastal vadose zones and aquifers is needed. Summary of the invention

[0004] The technical problem to be solved by the present invention is that, in view of the above-mentioned defects of the prior art, a method for estimating the hydrogeological parameters of a coastal aeration zone and aquifer is provided, and a system for estimating the hydrogeological parameters of a coastal aeration zone and aquifer is provided.

[0005] The technical solution adopted by the present invention to solve its technical problem is: A method for estimating hydrogeological parameters of aeration zones and aquifers in coastal zones is constructed, wherein the method comprises the steps of: An analytical model of groundwater flow movement including the influence of the vadose zone is established, and the analytical solution of the groundwater level in the aquifer driven by tides is obtained by solving the analytical model of groundwater flow movement. Collect borehole water level monitoring data of the hydrogeological parameters of the area to be estimated, and analyze the water level time series in the borehole water level monitoring data to obtain groundwater level fluctuations; The analytical solution of the groundwater level is fitted with the groundwater level fluctuation of the water level monitoring data, and the parameter values ​​corresponding to the fitting curve that meets the requirements are selected. The obtained parameter values ​​are used as the estimated values ​​of the hydrogeological parameters of the aeration zone and aquifer of the estimated area.

[0006] The method for estimating hydrogeological parameters of the coastal zone aeration zone and aquifer of the present invention, wherein the establishment of an analytical model of groundwater flow movement including the influence of the aeration zone, and the solution of the groundwater level of the aquifer under tidal drive by solving the analytical model of groundwater flow movement comprises: For the groundwater flow driven by tides, the vadose zone and the aquitard are both vertical one-dimensional flows, while the confined aquifer is vertical and horizontal two-dimensional flows; The interface between the saturated zone and the unsaturated zone is coupled by equal head and equal flux, and a coupling model of one-dimensional unsaturated zone, one-dimensional weak permeable layer and two-dimensional confined aquifer is obtained. The coupled model is solved by using mathematical analytical methods to obtain analytical solutions of groundwater levels at different tidal propagation locations and different depths in the aquifer driven by tides.

[0007] In the method for estimating hydrogeological parameters of the coastal aeration zone and aquifer of the present invention, the two-dimensional groundwater flow basic differential equation of the water flow movement in the confined aquifer and its initial and boundary conditions are described by the following control equations: In the formula is the confined aquifer head, is the hydraulic head of the confined aquifer at coordinate (x, y) at time t; and are the permeability coefficients of the confined aquifer in the x and z directions, respectively; is the elastic water storage / release rate of the confined aquifer; is the distance between the river and the inland water divide; is the time-varying hydraulic head at the boundary; is the thickness of the aquitard; is the thickness of the confined aquifer.

[0008] In the method for estimating hydrogeological parameters of the coastal aeration zone and aquifer described in the present invention, the one-dimensional groundwater flow basic differential equation of water flow movement in the aquitard is formulated as follows: Where: represents the aquitard head, is the permeability coefficient of the aquitard; is the elastic water storage rate / release rate of the aquitard; To move the diving surface.

[0009] In the method for estimating hydrogeological parameters of the coastal aeration zone and aquifer described in the present invention, the one-dimensional Richards equation for the motion of water flow in the unsaturated zone and its boundary conditions are as follows: In the formula is the total head of the vadose zone; is the relative permeability coefficient; is the soil volume moisture content; is the water capacity; is the pressure head of the aeration zone; is the thickness of the air-encapsulating zone.

[0010] The method for estimating hydrogeological parameters of the coastal zone aeration zone and aquifer of the present invention, wherein the control equation at the interface between the aeration zone and the weak permeable layer and the control equation at the interface between the weak permeable layer and the confined aquifer adopts the formula: .

[0011] The method for estimating hydrogeological parameters of the coastal aeration zone and aquifer of the present invention comprises linearizing the control equations (1a), (1b), (1c), (1d), (2), (3a), (3b), (4a), (4b), (4c), and (4d) so that the water table position is And apply the Gardner-Kozeny moisture characteristic curve model to the Richards equation, the simplified control equation is: In the formula, and , and are soil volume moisture content at rest Lower relative permeability and water content The zero-order approximation of is the soil moisture retention index, is the relative permeability index, is the water supply degree, and They are the pressure head where air begins to enter the saturated medium and where the relative permeability coefficient begins to equal 1; Expression of water level oscillation caused by ocean tides ,in is the complex amplitude, Angular frequency, is the tidal oscillation period, , convert the periodic head change into complex amplitude form: In the formula, for The complex amplitude of for The complex amplitude of for The complex amplitude of Substituting the above complex amplitude form into the control equations (5a), (5b), (5c), (5d), (5e), ​​(5f), (5g), (5h), (5i), (5j), (5k), we get the new control equations, which are expressed as: In the formula, ; right The variable substitution is performed to make the boundary conditions homogeneous so that the Fourier transform method can be used to solve equation (7h): in, Governed by a partial differential equation with homogeneous boundary conditions, the governing equations (7a), (7b), (7c), (7d), (7e), (7f), (7g), (7h), (7i), (7j), (7k) can be written as: Based on the integral transformation, eliminate The partial differential equation is converted into an ordinary differential equation. At the same time, in order to maintain the consistency of both sides of the equation, and Perform Fourier transform and express it in the following integral form: In the formula For the core, is the characteristic value, , It can be expressed as: Substituting equations (9a), (9b), and (9c) into equations (8a), (8b), (8c), (8d), (8e), (8f), (8g), (8h), (8i), (8j), and (8k) respectively, the control equations after integral transformation are obtained as follows: The general solutions of equations (11a), (11e) and (11h) are: In the formula, , , and They are Bessel functions of the first and second kind; Using equations (11b), (11c), (11d), (11f), (11g), and (11i), we can determine , , , , and The expression is: In the formula, the expressions of the introduced intermediate variables are: The groundwater level at a specific location in the vadose zone, aquitard and confined aquifer is calculated using the formula: .

[0012] The method for estimating hydrogeological parameters of aeration zones and aquifers in the coastal zone described in the present invention, wherein the hydrological parameters include water level data and time series data of boreholes; the time series obtained by monitoring is detrended, the tidal part is extracted, and groundwater level fluctuations are obtained.

[0013] The method for estimating hydrogeological parameters of the coastal zone aeration zone and aquifer of the present invention comprises fitting the analytical solution of the groundwater level with the groundwater level fluctuation of the water level monitoring data, selecting the parameter values ​​corresponding to the fitting curve that meets the requirements, and obtaining the parameter values ​​as the estimated values ​​of the hydrogeological parameters of the aeration zone and aquifer of the estimated area, which include: Draw a graph of the groundwater level changes over time of the monitoring data, and then use the analytical expression of the groundwater level to gradually adjust the hydrogeological parameters involved for fitting until the analytical solution can fit the monitoring data. At this time, the parameter values ​​corresponding to the analytical solution can be used to estimate the hydrogeological parameters of the aeration zone and aquifer in the area.

[0014] A system for estimating hydrogeological parameters of a coastal aeration zone and aquifer, which is applied to the method for estimating hydrogeological parameters of a coastal aeration zone and aquifer as described above, wherein the system comprises: a modeling unit, a data processing unit, a data acquisition unit and an image fitting unit; The modeling unit is used to establish an analytical model of groundwater flow movement including the influence of the vadose zone; The data acquisition unit is used to collect borehole water level monitoring data of the hydrogeological parameters of the site to be estimated; The data processing unit is used to solve the analytical model of groundwater flow movement to obtain an analytical solution of the groundwater level of the aquifer driven by tides, and to analyze the water level time series in the borehole water level monitoring data to obtain groundwater level fluctuations; The image fitting unit is used to fit the analytical solution of the groundwater level with the groundwater level fluctuation of the water level monitoring data, and select parameter values ​​corresponding to the fitting curve that meets the requirements; the obtained parameter values ​​are used as the estimated values ​​of the hydrogeological parameters of the aeration zone and the aquifer of the estimated area.

[0015] The beneficial effects of the present invention are as follows: based on the Richards equation describing the flow of groundwater in the vadose zone, the present invention establishes a mathematical model of groundwater flow in an unsaturated-saturated coupled aquifer driven by tides, obtains analytical solutions of groundwater levels at different locations in the vadose zone and aquifers by mathematical analytical methods, and fits with borehole observation data, which can effectively invert and estimate the hydrogeological parameters of the vadose zone and aquifers. This method helps to promote the further application of technologies based on the tidal response of groundwater levels in the field of hydrogeology, and provides a more accurate and reliable reference basis for the sustainable utilization and management of groundwater resources in coastal zones. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work: Figure 1 It is a flow chart of a method for estimating hydrogeological parameters of a coastal aeration zone and aquifer according to a preferred embodiment of the present invention; Figure 2 It is a schematic diagram of the unsaturated-saturated flow caused by tides in the method for estimating hydrogeological parameters of coastal aeration zone and aquifer in a preferred embodiment of the present invention; Figure 3 It is a time series diagram of water levels of boreholes at different positions in the method for estimating hydrogeological parameters of coastal aeration zone and aquifer in a preferred embodiment of the present invention; Figure 4 It is the best fitting line diagram of groundwater level and analytical solution of boreholes at different positions in the method for estimating hydrogeological parameters of coastal aeration zone and aquifer in a preferred embodiment of the present invention; Figure 5 It is a principle block diagram of the coastal aeration zone and aquifer hydrogeological parameter estimation system of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0018] The method for estimating hydrogeological parameters of the coastal zone aeration zone and aquifer in a preferred embodiment of the present invention is as follows: Figure 1 See also Figure 2-Figure 4 , the method comprises the steps of: S01: Establish an analytical model of groundwater flow movement including the influence of the vadose zone, and solve the analytical model of groundwater flow movement to obtain the analytical solution of the groundwater level of the aquifer driven by tides; S02: Collect borehole water level monitoring data of the hydrogeological parameters of the area to be estimated, and analyze the water level time series in the borehole water level monitoring data to obtain groundwater level fluctuations; S03: Fitting the analytical solution of the groundwater level with the groundwater level fluctuation of the water level monitoring data, selecting the parameter values ​​corresponding to the fitting curve that meets the requirements, and the obtained parameter values ​​are used as the estimated values ​​of the hydrogeological parameters of the aeration zone and the aquifer of the estimated area; Compared with the prior art, the present invention has the following advantages: 1. The method of the tidal response of the groundwater level in the present invention calculates the tidal response of the water level at the borehole, that is, the groundwater level fluctuation, based on the existing borehole water level observation data, and fits it with the analytical expression of the groundwater level obtained by the analytical model. The optimal curve fitting method is used to determine the corresponding hydrogeological parameters of the vadose zone and aquifer, and the measured results are linked to the theoretical results, fully mining the information of the observation data.

[0019] 2. The present invention fully includes the influence of the aeration zone on the tidal response of the groundwater level in the coastal zone, making the analytical model closer to the actual situation. The derivation is rigorous, and the present invention is simple to operate and easy to apply. It can provide a more accurate estimate of the hydrogeological parameters of the aeration zone and aquifer, and improve the traditional parameter estimation method.

[0020] The specific instructions are as follows: Step 1. For the tidally driven groundwater flow, the vadose zone and the aquitard are both vertical one-dimensional flows; the overflow confined aquifer is vertical and horizontal two-dimensional flows; for the interface between the saturated zone and the unsaturated zone, the head equality and flux equality are used for coupling; mathematical analytical methods are used to solve the analytical solutions of the groundwater levels at different tidal propagation positions and different depths of the aquifer under tidal drive.

[0021] Step 2. Collect the borehole water level time series data of the hydrological parameters to be estimated, preprocess the monitored time series (detrend), extract the tidal part, and obtain the groundwater level fluctuation.

[0022] Step 3. The analytical solution of groundwater obtained from the model is used to fit the groundwater level fluctuations of the corresponding data. When the optimal fitting line appears, it can be used to estimate the hydrogeological parameters of the aeration zone and aquifer in the area.

[0023] The specific contents of steps 1-3 are as follows: The tidal-driven groundwater flow model described in step 1 is a coupling model of a one-dimensional unsaturated zone, a one-dimensional weak permeable layer, and a two-dimensional leaky confined aquifer (hereinafter referred to as confined aquifer).

[0024] Furthermore, the two-dimensional groundwater flow basic differential equations and their initial and boundary conditions describing the water flow in the confined aquifer in step 1 can be described by the following governing equations: In the formula is the confined aquifer head [unit: ], is the hydraulic head of the confined aquifer at coordinate (x, y) at time t; and is the permeability coefficient of the confined aquifer in the x direction (horizontal direction) and the z direction (vertical direction) [unit: ]; is the elastic water storage rate / water release rate of the confined aquifer [unit: ]; is the distance between the river and the inland water divide [in L]; is the time-varying hydraulic head at the boundary (i.e., river level) [in L]; is the thickness of the aquitard [in L]; is the thickness of the confined aquifer [in L].

[0025] Furthermore, similar to the leaky confined aquifer, the one-dimensional groundwater flow basic differential equation for water movement in the weak permeable layer in step 1 can be written as: Where: Indicates the water head of the aquitard [unit: ], is the permeability coefficient of the aquitard [unit: ]; is the elastic water storage rate / water release rate of the aquitard [unit: ]; is the position of the mobile water table [unit: ].

[0026] Furthermore, the one-dimensional Richards equation describing the flow in the unsaturated zone and its boundary conditions in step 1 are written as: In the formula is the total head of the aeration zone [unit: ]; is the relative permeability coefficient [-]; is the soil volume moisture content [-]; is the water content [unit: L -1 ]; is the pressure head of the aeration zone [in L]; is the thickness of the vadose zone [unit: L].

[0027] Furthermore, the governing equations describing the interface between the vadose zone and the aquitard and the governing equations describing the interface between the aquitard and the confined aquifer in step 1 are written mainly based on the equality of the hydraulic head and flux at these locations: .

[0028] Furthermore, in order to facilitate the analytical solution, the control equations (1)-(4) are linearized so that the diving surface is located at and apply the Gardner-Kozeny moisture characteristic curve model to the Richards equation. The simplified governing equation can be written as: In the formula, and , and are the soil volume moisture content at rest Lower relative permeability and water content The zero-order approximation of Soil moisture index (reflects soil water holding capacity) [ ], is the relative permeability index (reflecting the permeability of soil) [ ], is the water supply degree, and are the pressure head [L] at the point where air begins to enter the saturated medium and at the point where the relative permeability begins to equal 1; Expression of water level oscillation caused by ocean tides ,in is the complex amplitude, Angular frequency[ ], is the tidal oscillation period [ ], , convert the periodic head change into complex amplitude form: In the formula, for The complex amplitude of for The complex amplitude of for The complex amplitude of Substituting the above complex amplitude form into the control equations (5a), (5b), (5c), (5d), (5e), ​​(5f), (5g), (5h), (5i), (5j), (5k), we get the new control equations, which are expressed as: In the formula, ; right The variable substitution is performed to make the boundary conditions homogeneous so that the Fourier transform method can be used to solve equation (7h): in, Governed by a partial differential equation with homogeneous boundary conditions, the governing equations (7a), (7b), (7c), (7d), (7e), (7f), (7g), (7h), (7i), (7j), (7k) can be written as: Based on the integral transformation, eliminate The partial differential equation is converted into an ordinary differential equation. At the same time, in order to maintain the consistency of both sides of the equation, and Perform Fourier transform and express it in the following integral form: In the formula For the core, is the characteristic value, , It can be expressed as: Substituting equations (9a), (9b), and (9c) into equations (8a), (8b), (8c), (8d), (8e), (8f), (8g), (8h), (8i), (8j), and (8k) respectively, the control equations after integral transformation are obtained as follows: The general solutions of equations (11a), (11e) and (11h) are: In the formula, , , and They are Bessel functions of the first and second kind; Using equations (11b), (11c), (11d), (11f), (11g), and (11i), we can determine , , , , and The expression is: In the formula, the expressions of the introduced intermediate variables are: The groundwater level at a specific location in the vadose zone, aquitard and confined aquifer is calculated using the formula: Furthermore, the hydrogeological data in step 2 include the water level data of the borehole and the time series data with a sufficiently long observation time. The data is detrended and the tidal part is extracted.

[0029] Furthermore, the graph of the groundwater level change over time of the monitoring data is plotted, and then the groundwater level analytical expression in step 1 is used to gradually adjust the various hydrogeological parameters involved for fitting until the analytical solution can better fit the monitoring data. At this time, the parameter values ​​corresponding to the analytical solution can be used to estimate the hydrogeological parameters of the aeration zone and aquifer in the area.

[0030] Combination Figure 2-Figure 4 The instructions are as follows: like Figure 2 As shown, the present invention establishes a groundwater flow model of an unsaturated-saturated coupled leakage aquifer driven by tides. The left boundary of the analytical model is a constant head boundary (tidal water level boundary), the right boundary is a water barrier boundary, the left and right intervals are L, and the interface between the aeration zone and the saturated zone is the water table, located at the origin , the top of the air-enclosing zone is impermeable.

[0031] The above steps are explained below with reference to a specific simulation example of borehole water level data.

[0032] like Figure 3 As shown, this embodiment uses continuous monitoring data of water levels in boreholes at different locations for 6 days with a resolution of 15 minutes. Figure 3 This is a time series diagram of the three boreholes.

[0033] like Figure 4 As shown in the figure, using the same set of parameters, the analytical expression of the groundwater level is compared with the monitoring data for matching. When the optimal matching combination appears, the estimated value of each hydrogeological parameter is determined as: , , , , , , , , .

[0034] In addition, due to the difficulty in obtaining hydrological data, the water level simulation data selected in this method is only used for illustration and is not intended to be limiting.

[0035] A system for estimating hydrogeological parameters of a coastal zone aeration zone and aquifer, applied to the method for estimating hydrogeological parameters of a coastal zone aeration zone and aquifer as described above, such as Figure 5 As shown, the system includes: a modeling unit 100, a data processing unit 101, a data acquisition unit 102 and an image fitting unit 103; A modeling unit 100, for establishing an analytical model of groundwater flow movement including the influence of the vadose zone; A data collection unit 102, for collecting borehole water level monitoring data of the hydrogeological parameters of the site to be estimated; The data processing unit 101 is used to solve the analytical model of groundwater flow movement to obtain the analytical solution of the groundwater level of the aquifer driven by tides, and to analyze the water level time series in the borehole water level monitoring data to obtain the groundwater level fluctuation; The image fitting unit 103 is used to fit the analytical solution of the groundwater level with the groundwater level fluctuation of the water level monitoring data, and select the parameter values ​​corresponding to the fitting curve that meets the requirements; the obtained parameter values ​​are used as the estimated values ​​of the hydrogeological parameters of the aeration zone and the aquifer of the estimated area; Based on the Richards equation describing the flow of groundwater in the vadose zone, the present invention establishes a mathematical model of groundwater flow in unsaturated-saturated coupled aquifers driven by tides. The groundwater level analytical solutions at different locations in the vadose zone and aquifers are obtained by mathematical analytical methods, and are fitted with borehole observation data, which can effectively invert and estimate the hydrogeological parameters of the vadose zone and aquifers. This method helps to promote the further application of technologies based on the tidal response of groundwater levels in the field of hydrogeology, and provide a more accurate and reliable reference basis for the sustainable utilization and management of groundwater resources in coastal zones.

[0036] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for estimating hydrogeological parameters of coastal aeration zone and aquifer, characterized in that: The method comprises the steps of: An analytical model of groundwater flow movement including the influence of the vadose zone is established, and the analytical solution of the groundwater level in the aquifer driven by tides is obtained by solving the analytical model of groundwater flow movement. Collect borehole water level monitoring data of the hydrogeological parameters of the area to be estimated, and analyze the water level time series in the borehole water level monitoring data to obtain groundwater level fluctuations; The analytical solution of the groundwater level is fitted with the groundwater level fluctuation of the water level monitoring data, and the parameter values ​​corresponding to the fitting curve that meets the requirements are selected. The obtained parameter values ​​are used as the estimated values ​​of the hydrogeological parameters of the aeration zone and aquifer of the estimated area.

2. The method for estimating hydrogeological parameters of coastal aeration zone and aquifer according to claim 1, characterized in that: The establishment of the groundwater flow movement analytical model including the influence of the vadose zone and the solution of the groundwater level of the aquifer under tidal drive by solving the groundwater flow movement analytical model include: For the groundwater flow driven by tides, the vadose zone and the aquitard are both vertical one-dimensional flows, while the confined aquifer is vertical and horizontal two-dimensional flows; The interface between the saturated zone and the unsaturated zone is coupled by equal head and equal flux, and a coupling model of one-dimensional unsaturated zone, one-dimensional weak permeable layer and two-dimensional confined aquifer is obtained. The coupled model is solved by using mathematical analytical methods to obtain analytical solutions of groundwater levels at different tidal propagation locations and different depths in the aquifer driven by tides.

3. The method for estimating hydrogeological parameters of coastal aeration zone and aquifer according to claim 2, characterized in that: The interface between the saturated zone and the unsaturated zone is coupled by equal head and flux, and a coupling model of one-dimensional unsaturated zone, one-dimensional weak permeable layer and two-dimensional confined aquifer is obtained; the coupling model is solved by mathematical analytical methods to obtain analytical solutions of groundwater levels at different tidal propagation positions and different depths of the aquifer under tidal drive, including: The basic two-dimensional groundwater flow differential equations for water movement in a confined aquifer and their initial and boundary conditions are described by the following governing equations: In the formula is the confined aquifer head, is the hydraulic head of the confined aquifer at coordinate (x, y) at time t; and are the permeability coefficients of the confined aquifer in the x and z directions, respectively; is the elastic water storage / release rate of the confined aquifer; is the distance between the river and the inland water divide; is the time-varying hydraulic head at the boundary; is the thickness of the aquitard; is the thickness of the confined aquifer; the basic differential equation for groundwater flow in aquitard is: Where: represents the aquitard head, is the permeability coefficient of the aquitard; is the elastic water storage rate / release rate of the aquitard; To move the position of the water table; The one-dimensional Richards equation for unsaturated zone water flow and its boundary conditions are as follows: In the formula is the total head of the vadose zone; is the relative permeability coefficient; is the soil volume moisture content; is the water capacity; is the pressure head of the aeration zone; is the thickness of the vadose zone; The governing equations at the interface between the aeration zone and the aquitard and at the interface between the aquitard and the confined aquifer are as follows: ; The control equations (1a), (1b), (1c), (1d), (2), (3a), (3b), (4a), (4b), (4c), (4d) are linearized to make the diving surface position And apply the Gardner-Kozeny moisture characteristic curve model to the Richards equation, the simplified control equation is: In the formula, and , and are the soil volume moisture content at rest Lower relative permeability and water content The zero-order approximation of is the soil moisture retention index, is the relative permeability index, is the water supply degree, and They are the pressure head where air begins to enter the saturated medium and where the relative permeability coefficient begins to equal 1; Expression of water level oscillation caused by ocean tides ,in is the complex amplitude, Angular frequency, is the tidal oscillation period, , convert the periodic head change into complex amplitude form: In the formula, for The complex amplitude of for The complex amplitude of for The complex amplitude of Substituting the above complex amplitude form into the control equations (5a), (5b), (5c), (5d), (5e), ​​(5f), (5g), (5h), (5i), (5j), (5k), we get the new control equations, which are expressed as: In the formula, ; right The variable substitution is performed to make the boundary conditions homogeneous so that the Fourier transform method can be used to solve equation (7h): in, Governed by a partial differential equation with homogeneous boundary conditions, the governing equations (7a), (7b), (7c), (7d), (7e), (7f), (7g), (7h), (7i), (7j), (7k) can be written as: Based on the integral transformation, eliminate The partial differential equation is converted into an ordinary differential equation. At the same time, in order to maintain the consistency of both sides of the equation, and Perform Fourier transform and express it in the following integral form: In the formula For the core, is the characteristic value, , It can be expressed as: Substituting equations (9a), (9b), and (9c) into equations (8a), (8b), (8c), (8d), (8e), (8f), (8g), (8h), (8i), (8j), and (8k) respectively, the control equations after integral transformation are obtained as follows: The general solutions of equations (11a), (11e) and (11h) are: In the formula, , , and They are Bessel functions of the first and second kind; Using equations (11b), (11c), (11d), (11f), (11g), and (11i), we can determine , , , , and The expression is: In the formula, the expressions of the introduced intermediate variables are: The groundwater level at a specific location in the vadose zone, aquitard and confined aquifer is calculated using the formula: .

4. The method for estimating hydrogeological parameters of coastal aeration zone and aquifer according to claim 1, characterized in that: The hydrological parameters include borehole water level data and time series data; the time series obtained by monitoring is detrended, and the tidal part is extracted to obtain groundwater level fluctuations.

5. The method for estimating hydrogeological parameters of coastal aeration zone and aquifer according to claim 1, characterized in that: The analytical solution of the groundwater level is fitted with the groundwater level fluctuation of the water level monitoring data, and the parameter values ​​corresponding to the fitting curve that meets the requirements are selected. The obtained parameter values ​​are used as the estimated values ​​of the hydrogeological parameters of the aeration zone and aquifer of the estimated area, including: Draw a graph of the groundwater level changes over time of the monitoring data, and then use the analytical expression of the groundwater level to gradually adjust the hydrogeological parameters involved for fitting until the analytical solution can fit the monitoring data. At this time, the parameter values ​​corresponding to the analytical solution can be used to estimate the hydrogeological parameters of the aeration zone and aquifer in the area.

6. A system for estimating hydrogeological parameters of aeration zones and aquifers in coastal zones, applied to the method for estimating hydrogeological parameters of aeration zones and aquifers in coastal zones as claimed in any one of claims 1 to 5, characterized in that: The system comprises: a modeling unit, a data processing unit, a data acquisition unit and an image fitting unit; The modeling unit is used to establish an analytical model of groundwater flow movement including the influence of the vadose zone; The data acquisition unit is used to collect borehole water level monitoring data of the hydrogeological parameters of the site to be estimated; The data processing unit is used to solve the analytical model of groundwater flow movement to obtain an analytical solution of the groundwater level of the aquifer driven by tides, and to analyze the water level time series in the borehole water level monitoring data to obtain groundwater level fluctuations; The image fitting unit is used to fit the analytical solution of the groundwater level with the groundwater level fluctuation of the water level monitoring data, and select parameter values ​​corresponding to the fitting curve that meets the requirements; the obtained parameter values ​​are used as the estimated values ​​of the hydrogeological parameters of the aeration zone and the aquifer of the estimated area.

Images