A method, system, device and medium suitable for the kinetic coupling simulation of four-water transformation and vegetation growth in arid shallow groundwater irrigation areas

Abstract

The present application relates to the technical field of hydrological model, and discloses a kind of dynamics coupling simulation method, system, equipment and medium suitable for four water transformation and vegetation growth of arid shallow groundwater irrigation area, the present application is closely coupled in space-time scale based on the equation of soil water-groundwater-surface water and improved crop growth model, and reasonably consider the influence of various agronomy, land management measures (such as surface covering, earth embankment, channel drain etc.) in irrigation area on water transformation, and the influence of soil salinization caused by shallow groundwater on plant root water absorption and growth, accurately and efficiently simulate the coupling process of four water transformation process and vegetation growth in arid shallow groundwater irrigation area, effectively ensure the accuracy and stability of the space-time dynamics of simulated soil water-groundwater-surface water and their interaction as well as accompanying process (salt migration) and crop growth condition, simulation efficiency is high, operability and practicality are strong.

Description

Technical Field

[0001] This invention relates to the field of hydrological modeling technology, and in particular to a dynamic coupling simulation method, system, equipment, and medium applicable to the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas. Background Technology

[0002] Distributed hydrological simulation is an effective method for elucidating watershed hydrological processes and quantitatively analyzing the complex dynamics of eco-hydrological systems. It is widely used in assessing water use efficiency, water resource management, and hydrological forecasting.

[0003] In arid irrigation areas, artificially modified farmland, scattered natural land, and a crisscrossing multi-level canal network profoundly alter underlying surface conditions. Simultaneously, irrigation and drainage activities create closer hydraulic connections and more frequent water transformations and associated processes (such as soil-groundwater exchange, lateral groundwater movement and exchange with drainage ditches, tiered drainage, and salt migration with water movement). Therefore, agricultural hydrological processes are highly complex and difficult to simulate accurately. Research on agricultural hydrological processes focuses more on the accuracy of farmland soil water (salt)-crop simulations, which is core to agricultural water management. Furthermore, with the implementation of agricultural water-saving measures (increasing canal lining and water-saving irrigation) and the joint management of groundwater and surface water, simulating modern agricultural irrigation areas requires considering more spatiotemporal details and demands higher simulation accuracy than simulating areas using traditional irrigation methods. For irrigation areas with shallow groundwater, efficient and accurate simulation of the four water transformation processes in agriculture not only helps improve the water use efficiency of the irrigation area itself but also plays a crucial role in achieving the rational allocation and utilization of water resources in the basin.

[0004] However, existing simulation methods still have shortcomings when applied to arid irrigation areas with shallow groundwater and significant human impact: (1) Some widely used conceptual models have low accuracy in simulating the spatiotemporal dynamics of soil water, groundwater, and surface water; (2) Most models do not adequately characterize the production-confluence process in arid agricultural watersheds and lack practical methods for simulating the confluence process of drainage ditches at different levels in irrigation areas; (3) When using the surface-subsurface fully coupled method to model agricultural watersheds with shallow groundwater, the strong nonlinearity of the three-dimensional vertical soil hydrodynamic equations makes it impossible to guarantee the accuracy and efficiency of the solution. It can be seen that existing simulation methods lack the ability to uniformly characterize the coupling relationship between soil water (salt)-groundwater-surface water transport and vegetation growth in arid irrigation areas with shallow groundwater from a mechanistic perspective, and are difficult to apply well in practice.

[0005] Therefore, there is an urgent need for a new dynamic coupling simulation method, system, equipment, and medium applicable to the transformation of the four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas. This would allow for a more accurate simulation of the spatiotemporal dynamics of soil water, groundwater, and surface water, as well as their interactions, associated processes (salt migration), and crop growth, thus meeting the needs of quantitative research on the dynamic hydrological cycle in arid irrigation areas. Summary of the Invention

[0006] This invention provides a dynamic coupling simulation method, system, equipment, and medium for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas. This addresses the shortcomings of existing simulation methods, which lack the ability to uniformly characterize the coupling relationship between soil water (salt), groundwater, and surface water transport and vegetation growth in arid, shallowly buried groundwater irrigation areas, making them difficult to apply effectively in practice.

[0007] This invention provides a dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas, comprising:

[0008] S0. Obtain channel drainage data, soil water data, groundwater data, surface water data, and planting structure data of the irrigation area to be simulated;

[0009] S1. Based on the channel drainage data and planting structure data of the irrigation area to be simulated, the irrigation area to be simulated is divided into several sub-basins, and each sub-basin is further divided into several hydrological response units according to land type and planting structure. The unsaturated soil water and salt transport process of each hydrological response unit is simulated.

[0010] S2. Based on the groundwater data of the irrigation area to be simulated, and combined with the impact of channel leakage, drainage ditch and soil water on groundwater, the groundwater dynamics of the irrigation area to be simulated are simulated using an improved groundwater flow model.

[0011] S3. Based on the surface water data of the irrigation area to be simulated, and combined with the surface runoff, low-level drainage volume and groundwater in the sub-basin, the confluence and evolution process of surface water flow in the irrigation area to be simulated is simulated.

[0012] S4. The improved crop growth model was used to simulate the crop growth in the irrigation area to be simulated, and it was closely coupled with the soil water and salt simulation process to obtain the dynamic coupling simulation model of the four water transformations and vegetation growth in the irrigation area to be simulated.

[0013] S5. Based on the simulation results of S1-S4, the interaction between soil water, groundwater and surface water in the irrigation area to be simulated is coupled and simulated using the spatiotemporal coupling method.

[0014] According to the present invention, a dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas is provided, wherein S1 includes:

[0015] The vertical one-dimensional flow motion of each hydrological response unit in several hydrological response units was simulated using the vertical soil hydrodynamic equation.

[0016] The solute transport process in the soil of each of several hydrological response units was simulated using solute transport equations.

[0017] The vertical soil hydrodynamic equation is as follows:

[0018] ,

[0019] In the vertical soil hydrodynamic equation, θ Indicates soil volumetric water content (cm³) 3 cm -3 ); t Indicates time (day); z Indicates the depth below ground level (cm, upward indicates positive); S a Indicates soil water source sink (cm) 3 cm -3 d -1 (i.e., root system water absorption). h s Indicates soil pressure head (cm); K ( h S ) represents soil hydraulic conductivity (cmd) -1 );

[0020] The solute transport equation is:

[0021] ,

[0022] In the solute transport equation, θ Indicates soil volumetric water content (cm³) 3 cm -3 ); ρ b Indicates the dry bulk density of soil (g / cm³) -3 ); q Represents soil water flux between nodes (cmd) -1 ); c Indicates soil salinity concentration (g / L) -1 ); z Indicates the depth below ground level (cm, upward indicates positive); D dif The solute diffusion coefficient (cm) 2 d -1); D dis Indicates the hydrodynamic dispersion length (cm); Q This indicates the amount of solute adsorbed by the soil (gg). -1 ); S s Indicates solute source sink (gcm) -3 d -1 ).

[0023] According to the present invention, a dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas is provided, wherein S2 includes:

[0024] The water yield of the irrigation district to be simulated is updated using a variable water yield formula.

[0025] The leakage rate of low-level channels in the irrigation area to be simulated is obtained using the channel leakage rate formula.

[0026] Combining the updated water supply, the channel leakage of the low-level channels in the irrigation area to be simulated, and the exchange of soil water and groundwater obtained through S1, the groundwater dynamics of the irrigation area to be simulated are simulated using an improved groundwater flow model through a three-dimensional groundwater flow motion equation.

[0027] The formula for variable feedwater concentration is:

[0028] ,

[0029] In the formula for variable water yield, S y This indicates the updated water supply level; θ s , θ r These represent saturated moisture content and residual moisture content (cm). 3 cm -3 ); d Indicates the depth of groundwater (m); α (cm) -1 )and n (-) indicates an empirical parameter for shape; d 0 represents the critical value for groundwater depth. S ycons express exist d The specific yield above 0 is assumed to be expressed as a conventional constant (m);

[0030] The formula for channel leakage is:

[0031] ,

[0032] In the formula for channel leakage, CS kThis represents the channel leakage (mmd) within the k-th hydrological response unit. -1 ); K c,sat Indicates the effective saturated hydraulic conductivity (mmd) of the channel bottom. -1 ); X The wetted perimeter (m) is estimated based on the irrigation water volume given in each hydrological response unit. L c,k This represents the channel length (m) within the kth hydrological response unit. A k This represents the area (m²) of the k-th hydrological response unit. 2 );

[0033] The three-dimensional equations for groundwater flow are:

[0034] ,

[0035] In the three-dimensional equations of groundwater flow, K xx , K yy and K zz Let md represent the hydraulic conductivity along the x, y, and z coordinate axes, respectively. -1 ); h Indicates groundwater head (m); t Indicates time (day); W The source term (m) represents the amount of water flowing into or out of a unit volume of aquifer per unit time. S y and S s These represent the specific yield and storage coefficient of the porous medium, respectively. -1 ).

[0036] According to the present invention, a dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas is provided, wherein S3 includes:

[0037] The surface runoff and low-level drainage volume in the sub-basin were obtained using the Hooghoudt equation.

[0038] The surface runoff, drainage volume of low-level drainage ditches, and aquifer-river section exchange volume obtained through S2 within the sub-basin are combined to simulate the surface water flow in the simulated irrigation area. The confluence and evolution process of surface water flow in the simulated irrigation area is simulated using the one-dimensional diffusion wave equation.

[0039] The Hooghoudt equation is as follows:

[0040] ,

[0041] ,

[0042] ,

[0043] In the Hooghoudt equation, Q g Indicates drainage volume (md) -1 ),in, Q g,hru and Q g,sub These represent the drainage volume of the hydrological response unit and the sub-basin, respectively. GWD The depth of groundwater (m); j For simulated dates (-); K e Indicates lateral hydrotropism (md) -1 ); m m Indicates the groundwater surface drainage elevation (m); d e Indicates the equivalent depth (m); d d Indicates the depth of the impermeable layer (m); L d Indicates the spacing between drainage ditches (m); nHRU This indicates the number of hydrological response units in a sub-basin; A HRU Represents the area (m²) of a hydrological response unit. 2 );

[0044] The equation for a one-dimensional diffused wave is:

[0045] ,

[0046] In the one-dimensional diffusion wave equation, V Represents the volume (m) of any control volume 3 ); t Indicates time (days); nconn Indicates the number of connections to the control unit; A Represents cross-sectional area (m 2 ); H Indicates the surface water level (m) above the reference level; x Represents spatial coordinates (m); Q LAT This represents the source and sink items (i.e., surface runoff and low-level drainage in the sub-basin, in m³). 3 d -1 Volumetric flow rate; Q PR Indicates rainfall (m) 3 d -1 );Q EV Evaporation amount (m 3 d -1 ); Q AQ Indicates the aquifer-river reach exchange rate (m³). 3 d -1 ); D Mi Describes a nonlinear diffusion term (md -1 ).

[0047] According to the present invention, a dynamic coupling simulation method for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas is provided, wherein S4 includes:

[0048] Using an improved crop growth model, the potential root water uptake, actual root water uptake, actual transpiration rate, and plant growth regulators of crops in the simulated irrigation area were obtained through expressions for potential root water uptake, actual root water uptake, actual transpiration rate, and plant growth regulators.

[0049] Based on the potential root water uptake, actual root water uptake, actual transpiration rate, and plant growth regulators of crops in the irrigation area to be simulated, the growth of crops in the irrigation area to be simulated is simulated, and coupled with soil water and salt simulation, a dynamic coupled simulation model of the irrigation area to be simulated is obtained.

[0050] The expression for potential root water absorption is as follows:

[0051] ,

[0052] In the expression for potential root water uptake, S p The potential root water uptake at a specific node z (cm d) -1 ); D root Indicates the deepest root depth on that day (cm); T p Indicates the potential evaporation rate of plants unaffected by water and salt stress (cm d). -1 It uses the leaf area index (LAI) to measure potential evapotranspiration (ET). p , cm d -1 The division represents potential soil evaporation (E) p , cm d -1 ) and plant transpiration (T) p , cm d -1 ) the result; I root Represents the root length density at a specific node at depth z (cm cm) -3 );

[0053] The expression for actual root water absorption is:

[0054] ,

[0055] In the actual root water absorption expression, S a This represents the actual root water absorption (cm d) at a specific node z. -1 ); α rw (-)and α rs (-) represent the reduction coefficients for water stress and salt stress, respectively;

[0056] The actual transpiration rate is expressed as:

[0057] ,

[0058] In the actual transpiration rate expression, T a Indicates the actual transpiration rate (cm d) -1 ); S a This represents the actual root water absorption (cm d) at a specific node z. -1 ); D root Indicates the deepest root depth on that day (cm);

[0059] The expression for plant growth regulators is:

[0060] ,

[0061] In the expression of plant growth regulators, γ reg This refers to plant growth regulators, which are a portion of the potential growth that can be achieved within a given day. α rw (-)and α rs (-) represent the reduction coefficients for water stress and salt stress, respectively; strs t This indicates the temperature stress coefficient (-).

[0062] According to the present invention, a dynamic coupling simulation method for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas is provided, wherein S5 includes:

[0063] Based on the simulation results of S1-S4, the interaction between soil water, groundwater and surface water in the simulated irrigation area is coupled and simulated in the time dimension by combining sequential coupling and iterative coupling.

[0064] In the spatial dimension, the interaction between soil water, groundwater, and surface water in the irrigation area to be simulated is coupled and simulated using mapping expressions.

[0065] The mapping expression is:

[0066] ,

[0067] ,

[0068] ,

[0069] In the mapping expression, RECH grid This represents the daily cumulative net vertical recharge (m) for each groundwater grid in the groundwater simulation. nDHRU This indicates the number of DHRUs that overlap with the groundwater grid. DHRUs represent independent sub-hydrological response units decomposed by HRUs. CS DHRU,p and The soil bottom flux, channel leakage and drainage (mm) are respectively the independent sub-hydrological response units. A overlap Represents the overlapping area (m 2 ); A grid The area of ​​the groundwater grid (m²) 2 ), GWD grid,p Indicates the groundwater depth (m) of each groundwater grid; nGRID Indicates the number of DHRUs that overlap with the groundwater grid; A DHRU,p and A HRU Represent the areas (m²) of DHRU and HRU respectively. 2 ); GWD DHRU,p and GWD HRU These represent the groundwater depth (m) for DHRU and HRU, respectively.

[0070] According to the present invention, a dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas is provided. The method, in the time dimension, combines sequential coupling and iterative coupling to perform a coupled simulation of the interactions between soil water, groundwater, and surface water in the irrigation area to be simulated, including:

[0071] The unsaturated zone soil water and salt transport processes and groundwater dynamics of the irrigation area to be simulated were solved by sequential coupling.

[0072] An iterative coupling approach is used to solve the dynamics of groundwater and the confluence evolution of surface water in the irrigation area to be simulated until the preset convergence criteria are met.

[0073] Using mapping expressions, the interaction between soil water, groundwater, and surface water in the irrigation district to be simulated is coupled in space.

[0074] The expression for the preset convergence criterion is:

[0075] ,

[0076] In the expression for the predefined convergence criterion, Q AQii This represents the aquifer-residence exchange rate (m³) of the current external iteration of the surface water simulation for receptacle ii. 3 d -1 ); Q MFii This represents the aquifer-residence exchange rate (m) of the current external iteration of the groundwater simulation for receptacle ii. 3 d -1 ); f AQmax This indicates the maximum allowable relative difference in aquifer-river section exchange rate across any river section. nr This represents the number of river segments in the surface water dataset.

[0077] This invention also provides a dynamic coupling simulation system for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas, comprising:

[0078] The data acquisition module is used to execute S0: acquire channel drainage data, soil water data, groundwater data, surface water data, and planting structure data of the irrigation area to be simulated;

[0079] The soil water simulation module is used to perform S1: Based on the channel drainage data and planting structure data of the irrigation area to be simulated, the irrigation area to be simulated is divided into several sub-basins, and each sub-basin is divided into several hydrological response units according to land type and planting structure, and the unsaturated zone soil water and salt transport process of each hydrological response unit is simulated.

[0080] The groundwater simulation module is used to execute S2: Based on the groundwater data of the irrigation area to be simulated, and combined with the impact of channel leakage, drainage ditch and soil water on groundwater, the improved groundwater flow model is used to simulate the groundwater dynamics of the irrigation area to be simulated.

[0081] The surface water simulation module is used to execute S3: based on the surface water data of the irrigation area to be simulated, combined with the surface runoff, low-level drainage volume and groundwater in the sub-basin, the confluence and evolution process of surface water flow in the irrigation area to be simulated is simulated.

[0082] The crop growth simulation module is used to execute S4: using an improved crop growth model to simulate the crop growth in the irrigation area to be simulated, and tightly coupling it with the soil water and salt simulation process to obtain a dynamic coupling simulation model of the four water transformations and vegetation growth in the irrigation area to be simulated.

[0083] The coupled simulation module is used to execute S5: based on the simulation results of S1-S4, it uses the spatiotemporal coupling method to couple the interaction between soil water, groundwater and surface water in the irrigation area to be simulated.

[0084] The present invention also provides an electronic device, including a processor and a memory storing a computer program, wherein the processor executes the computer program to implement any of the above-described dynamic coupling simulation methods for the transformation of four types of water and vegetation growth in arid groundwater shallow-buried irrigation areas.

[0085] The present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the dynamic coupling simulation method for the transformation of four waters and vegetation growth in shallow buried irrigation areas of arid groundwater as described above.

[0086] The present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute any of the above-described dynamic coupling simulation methods for the transformation of four types of water and vegetation growth in arid groundwater shallow-buried irrigation areas.

[0087] This invention provides a dynamic coupling simulation method, system, equipment, and medium applicable to the transformation of four water systems and vegetation growth in arid, shallowly buried groundwater irrigation areas. It accurately simulates the dynamics of soil water (salt), groundwater, and surface water using kinetic equations and employs an improved crop growth model to simulate vegetation growth. Furthermore, it relies on an efficient spatiotemporal coupling method to rationally describe the complex interactions of various water systems in time and space, precisely simulating the transformation of four water systems and vegetation growth in arid, shallowly buried groundwater irrigation areas. This invention reasonably considers the impact of various agronomic and land management measures (such as surface cover, earthen embankments, canals, and drainage ditches) on water transformation in arid irrigation areas, while also considering the impact of soil salinization caused by shallow groundwater burial on plant root water absorption and growth. This invention has significant advantages in simulation accuracy and computational efficiency, is simple and convenient to operate, and provides clear results output, making it highly practical. Attached Figure Description

[0088] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0089] Figure 1 This is one of the flowcharts of a dynamic coupling simulation method for the transformation of four types of water and vegetation growth in arid, shallowly buried groundwater irrigation areas provided by the present invention.

[0090] Figure 2 The second schematic diagram of the dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid groundwater shallow-buried irrigation areas provided by the present invention;

[0091] Figure 3 This is a schematic diagram of the "mapping" method between different spatial divisions (hydrological response units, groundwater grid units, and surface water river segments) of the present invention;

[0092] Figure 4 This is a schematic diagram of the geographical location of Embodiment 1 of the present invention;

[0093] Figure 5 The simulation results of soil moisture content and soil salinity in the cornfield in Example 1 of the present invention are shown in the figure, and the comparison with the measured values ​​are also shown.

[0094] Figure 6 This is a comparison chart of the simulated groundwater results and measured values ​​from four observation wells in Embodiment 1 of the present invention.

[0095] Figure 7 This is a diagram showing the dynamic changes of groundwater space before and after irrigation during the simulation of Embodiment 1 of the present invention;

[0096] Figure 8 The simulation results of crop leaf area index in Example 1 of the present invention and the comparison with the measured values ​​are shown in the figure.

[0097] Figure 9 The following is a comparison chart of the simulated soil moisture content and soil salinity at 22 observation points in Example 2 of this invention with the measured values;

[0098] Figure 10 This is a comparison chart of the simulated groundwater levels of 12 wells in Embodiment 2 of the present invention and the measured values.

[0099] Figure 11 This is a comparison chart of the simulated flow rate at six drainage ditch sections in Embodiment 2 of the present invention and the measured values.

[0100] Figure 12 A schematic diagram of a dynamic coupling simulation system for the transformation of four types of water and vegetation growth in arid, shallowly buried groundwater irrigation areas provided by the present invention.

[0101] Figure 13 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0102] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0103] Figure 1 This is a schematic flowchart illustrating a dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas, provided by this invention. The executing entity of this dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas can be any suitable terminal-side device or network-side device, such as a dynamic coupling simulation device for the transformation of four waters and vegetation growth in arid, shallowly buried groundwater irrigation areas.

[0104] See Figure 1 The present invention provides a dynamic coupling simulation method for the transformation of four types of water and vegetation growth in arid, shallowly buried groundwater irrigation areas, which may include:

[0105] S0. Obtain channel and drainage data, soil water data, planting structure data, groundwater level data, and surface water flow (or water level) data for the irrigation area to be simulated.

[0106] In this embodiment, the irrigation area to be simulated is an arid, shallowly buried groundwater irrigation area. The channel drainage data may include data such as channel drainage cross-sectional dimensions, roughness, and geographical location. The soil water data may include data such as soil classification, soil water content, and salinity.

[0107] S1. Based on the channel drainage data of the irrigation area to be simulated (in this embodiment, the geographical location data of the channel drainage), the irrigation area to be simulated is divided into several sub-basins (i.e., irrigation units). The areas with the same land use, soil type and slope in each of the several sub-basins are divided into different hydrological response units (HRUs). The soil profile of each HRU is discretized in the vertical direction into soil layers of the same or different thicknesses (i.e., one-dimensional finite difference grids). The unsaturated soil water and salt transport process of each of the several hydrological response units is simulated by using the vertical soil hydrodynamic equation and the solute-transport equation.

[0108] In one embodiment, S1 includes:

[0109] S101. The vertical one-dimensional flow motion of each hydrological response unit in several hydrological response units is simulated using the vertical soil hydrodynamic equation (Richards equation in this embodiment).

[0110] The vertical Richards equation is as follows:

[0111] ,

[0112] In the vertical Richards equation, θ Indicates soil volumetric water content (cm³) 3 cm -3 ); t Indicates time (day); z Indicates the depth below ground level (cm, upward indicates positive); S a Indicates soil water source sink (cm) 3 cm -3 d -1 (i.e., root system water absorption). h s Indicates soil pressure head (cm); K ( h S ) represents soil hydraulic conductivity (cmd) -1 );

[0113] In this embodiment, for soil water flow, the upper boundary is controlled based on the actual soil evaporation rate and fluxes calculated from irrigation and precipitation, while allowing water accumulation in the field. The soil evaporation rate is adjusted by multiplying the potential soil evapotranspiration by the mulch reduction coefficient to reasonably estimate the impact of surface mulch on soil evaporation. To fully utilize incoming water, earthen embankments are typically constructed around farmland, leading to water accumulation when rainfall or irrigation fails to infiltrate. Water accumulation is only permitted when the water depth exceeds the user-specified maximum water accumulation height (…). z sillSurface runoff only occurs when the temperature reaches a certain level (cm). In this embodiment, the surface runoff volume generated in each HRU is calculated according to the following formula:

[0114] ,

[0115] In the formula, q runoff Surface runoff (cm d) -1 ); γ sill Indicates runoff resistance (d); β sill Indicates an exponential parameter (-); h pond Indicates the depth of the water (cm); z sill Indicates the maximum height of the accumulated water (cm).

[0116] In shallow groundwater basins, the lower soil boundary is typically a variable head boundary determined by the groundwater depth.

[0117] ,

[0118] In the formula, h bot The pressure head (cm) at the bottom node of the soil. z bot Indicates the depth of the bottom node in the soil (cm, upwards indicates positive); GWD Indicates the depth of groundwater (m); j Indicates the date of calculation (-).

[0119] S102. The solute transport process in the soil of each of the several hydrological response units is simulated using the solute transport equation (convection-dispersion equation, ADE in this embodiment).

[0120] The convection-diffusion equation is as follows:

[0121] ,

[0122] In the convection-dispersion equation, θ Indicates soil volumetric water content (cm³) 3 cm -3 ); ρ b Indicates the dry bulk density of soil (g / cm³) -3 ); q Represents soil water flux between nodes (cmd) -1 ); c Indicates soil salinity concentration (g / L) -1 ); zIndicates the depth below ground level (cm, upward indicates positive); D dif The solute diffusion coefficient (cm) 2 d -1 ); D dis Indicates the hydrodynamic dispersion length (cm); Q This indicates the amount of solute adsorbed by the soil (gg). -1 ); S s Indicates solute source sink (gcm) -3 d -1 For solute transport simulation, the upper and lower boundary conditions in this embodiment are set as concentration flux boundaries. A fully implicit finite difference scheme can be used for numerical solution, and the Grid Peclet number and Courant number are utilized to ensure the accuracy and stability of the solution.

[0123] S2. Based on the groundwater data of the irrigation area to be simulated, and combined with the influence of channel leakage and the amount of soil water exchanged with groundwater obtained through S1 on the groundwater, the groundwater dynamics of the irrigation area to be simulated are simulated using an improved groundwater flow model (improved MODFLOW-NWT model).

[0124] In one embodiment, S2 includes:

[0125] The water yield of the irrigation district to be simulated is updated using a variable water yield formula.

[0126] The leakage rate of low-level channels (i.e., farm canals and field canals that mainly serve the function of conveying water to the field) in the irrigation area to be simulated is obtained by using the channel leakage rate formula.

[0127] Combining the updated water supply, the channel leakage of low-level channels in the irrigation area to be simulated, and the exchange of soil water and groundwater obtained through S1, the groundwater dynamics of the irrigation area to be simulated are simulated using an improved groundwater flow model and groundwater dynamic simulation equations.

[0128] The amount of soil water exchanged with groundwater obtained in S1 is:

[0129]

[0130] In the formula, θ bot This represents the amount of water exchanged between soil and groundwater. θ bot For soil upper boundary flux; SW end The water content at the end of the soil hydrodynamic equation calculation; SW ini Calculate the initial water content for the soil hydrodynamic equation;

[0131] The formula for variable feedwater concentration is:

[0132] ,

[0133] In the formula for variable water yield, S y This indicates the updated water supply level; θ s , θ r These represent saturated moisture content and residual moisture content (cm). 3 cm -3 ); d Indicates the depth of groundwater (m); α (cm) -1 )and n (-) indicates an empirical parameter for shape; d 0 represents the critical value for groundwater depth. S ycons express exist d The specific yield above 0 is assumed to be expressed as a conventional constant (m);

[0134] The formula for channel leakage is:

[0135] ,

[0136] In the formula for channel leakage, CS k This represents the channel leakage (mmd) within the k-th hydrological response unit. -1 ); K c,sat Indicates the effective saturated hydraulic conductivity (mmd) of the channel bottom. -1 ); X The wetted perimeter (m) is estimated based on the irrigation water volume given in each hydrological response unit. L c,k This represents the channel length (m) within the kth hydrological response unit. A k This represents the area (m²) of the k-th hydrological response unit. 2 For higher-level channels (such as main canals and branch canals) in the irrigation area, due to their greater burial depth and better connectivity with groundwater, the leakage of the channels is directly set as the flux boundary of the corresponding groundwater grid in the first layer of groundwater simulation. This leakage is usually determined by the flow rate and water use efficiency of the higher-level channels.

[0137] The equations for groundwater dynamics simulation (three-dimensional groundwater flow motion equations) are as follows:

[0138] ,

[0139] In the three-dimensional equations of groundwater flow, K xx , K yy and K zz Let md represent the hydraulic conductivity along the x, y, and z coordinate axes, respectively. -1 ); h Indicates groundwater head (m); t Indicates time (day); W The source term (m) represents the amount of water flowing into or out of a unit volume of aquifer per unit time. S y and S s These represent the specific yield and storage coefficient of the porous medium, respectively. -1 ).

[0140] In aquifer properties that control groundwater flow, specific yield is influenced by various factors such as soil water-holding capacity, groundwater depth, and its rate of change, especially when the groundwater depth is shallow. Therefore, a variable specific yield formula is introduced to update the specific yield of each grid cell before the start of each day's simulation, thereby improving the simulation accuracy in shallow groundwater conditions in this embodiment. Meanwhile, the specific yield can still be specified as a constant value by the user directly in the input file.

[0141] S3. Based on the surface water data of the irrigation area to be simulated, and combined with the influence of surface runoff, low-level drainage volume, and aquifer-river section exchange volume obtained through S2 on the surface water flow of the irrigation area to be simulated, the confluence and evolution process of surface water flow in the irrigation area to be simulated is simulated.

[0142] In one embodiment, S3 includes:

[0143] The surface runoff and drainage volume of low-level drainage ditches (i.e., agricultural ditches) within the sub-basin were obtained using the Hooghoudt equation.

[0144] The surface runoff in the sub-basin, the drainage volume of low-level drainage ditches, and the aquifer-river section exchange volume obtained through S2 are combined to simulate the surface water flow of the simulated irrigation area. The one-dimensional diffusion wave equation is used to simulate the confluence and evolution process of the surface water flow (i.e., receiving drainage from low-level drainage ditches and transporting it to high-level drainage ditches outside the irrigation area, such as main ditches, tributaries, and branch ditches) in the simulated irrigation area.

[0145] The aquifer-river section exchange rate obtained through S2 is as follows:

[0146]

[0147] In the formula, C iiIndicates river section ii The hydraulic conductivity of the aquifer; h ji, Indicates the included river section ii The groundwater unit (the first) j Column, No. i The groundwater level (in the row); H ji Indicates river section ii Surface water level;

[0148] The Hooghoudt equation is:

[0149] ,

[0150] ,

[0151] ,

[0152] In the Hooghoudt equation, Q g Indicates drainage volume (md) -1 ),in, Q g,hru and Q g,sub These represent the drainage volume of the hydrological response unit and the sub-basin, respectively. GWD The depth of groundwater (m); j For simulated dates (-); K e Indicates lateral hydrotropism (md) -1 ); m m Indicates the groundwater surface drainage elevation (m); d e Indicates the equivalent depth (m); d d Indicates the depth of the impermeable layer (m); L d Indicates the spacing between drainage ditches (m); nHRU This indicates the number of hydrological response units in a sub-basin; A HRU Represents the area (m²) of a hydrological response unit. 2 );

[0153] The equation for a one-dimensional diffused wave is:

[0154] ,

[0155] In the one-dimensional diffusion wave equation, V Represents the volume (m) of any control volume 3 ); t Indicates time (days); nconn Indicates the number of connections to the control unit; A Represents cross-sectional area (m 2 ); H Indicates the surface water level (m) above the reference level; x Represents spatial coordinates (m); Q LAT This represents the source and sink items (i.e., surface runoff and low-level drainage in the sub-basin, in m³). 3 d -1 Volumetric flow rate; Q PR Indicates rainfall (m) 3 d -1 ); Q EV Evaporation amount (m 3 d -1 ); Q AQ Indicates the aquifer-river reach exchange rate (m³). 3 d -1 ); D Mi Describes a nonlinear diffusion term (md -1 The ), can be defined using the Manning formula. In arid agricultural watersheds, the drainage ditches of channels and ditches are typically much smaller than finite difference grids, and the effects of rainfall and evaporation have already been considered in the unsaturated zone. Therefore, this embodiment defaults to a for each river segment Q PR and Q EV The value is zero. Furthermore, to solve the one-dimensional spreading wave equation, the user needs to specify the initial water level and upstream boundary conditions in advance (i.e., ...). Q inlet = Q ( t and downstream boundary conditions (e.g., h outlet = h ( t ), Q outlet = Q ( t )and Q outlet = Q ( t The water level-discharge relationship of the downstream boundary conditions can be specified by the user or derived from information on downstream hydraulic structures (such as weirs, pumps, and gates). For example, the improved form of the general weir equation used in this embodiment can describe the free outflow and submerged outflow processes affected by the weir:

[0156] ,

[0157] ,

[0158] In the formula, Q s Indicates free outflow or submerged outflow (m) 3 d -1 ); C D Indicates the weir flow coefficient (-); C F Indicates the flooding coefficient (-); W S The length of the weir (m) is perpendicular to the direction of water flow. h STR Indicates the elevation of the bottom of the weir (m); h max This represents the maximum elevation of the weir bottom (m). g Expressing gravitational acceleration (ms) -2 ).

[0159] S4. The improved crop growth model is used to simulate the crop growth in the irrigation area to be simulated (e.g., leaf area index, crop height, root depth, biomass and yield), and it is coupled with the soil water and salt simulation (i.e. the simulation results of S1) to obtain the dynamic coupling simulation model of the four water transformations and vegetation growth in the irrigation area to be simulated.

[0160] Actual water uptake by plant roots is the primary source and sink factor for calculating soil water movement. Soil water content and salinity also affect actual water uptake by crops. This embodiment quantifies the stress of unsuitable environments (i.e., water, salt, and temperature) on root water uptake, transpiration, and crop growth by calculating soil water-salt, temperature stress coefficients, and plant growth regulators. Crop growth status (LAI, root depth) affects actual root water uptake by influencing potential plant transpiration and root length density.

[0161] In one embodiment, S4 includes:

[0162] Using an improved crop growth model (in this embodiment, the improved EPIC_CG model), the potential root water uptake, actual root water uptake, actual transpiration rate, and plant growth regulators of the crops in the irrigation area to be simulated are obtained through expressions for potential root water uptake, actual root water uptake, actual transpiration rate, and plant growth regulators.

[0163] Based on the potential root water uptake, actual root water uptake, actual transpiration rate, and plant growth regulators of crops in the irrigation area to be simulated, the growth of crops in the irrigation area to be simulated is simulated, and coupled with soil water and salt simulation, a dynamic coupled simulation model of the irrigation area to be simulated is obtained.

[0164] In this embodiment, the potential soil root water uptake at a certain soil node (soil layer) is calculated by distributing the potential plant transpiration rate to each soil layer of the soil profile. It is a function of the specified root length density, i.e., the expression for the potential root water uptake is:

[0165] ,

[0166] In the expression for potential root water uptake, S p The potential root water uptake at a specific node z (cm d) -1 ); D root Indicates the deepest root depth on that day (cm); T p Indicates the potential evaporation rate of plants unaffected by water and salt stress (cm d). -1 It uses the leaf area index (LAI) to measure potential evapotranspiration (ET). p , cm d -1 The division represents potential soil evaporation (E) p , cm d -1 ) and plant transpiration (T) p , cm d -1 ) the result; I root Represents the root length density at a specific node at depth z (cm cm) -3 The value can be specified by the user and determined based on the ratio of the node depth to the node depth where the maximum root length for that day is located.

[0167] The expression for actual root water absorption is:

[0168] ,

[0169] In the actual root water absorption expression, S a This represents the actual root water absorption (cm d) at a specific node z. -1 ); α rw (-)and α rs (-) represent the reduction coefficients for water stress and salt stress, respectively;

[0170] The actual transpiration rate is expressed as:

[0171] ,

[0172] In the actual transpiration rate expression, T a Indicates the actual transpiration rate (cm d) -1 ); Sa This represents the actual root water absorption (cm d) at a specific node z. -1 ); D root Indicates the deepest root depth on that day (cm);

[0173] The effects of environmental stress on plant growth are quantified using plant growth regulators, which are expressed as follows:

[0174] ,

[0175] In the expression of plant growth regulators, γ reg This refers to plant growth regulators, which are a portion of the potential growth that can be achieved within a given day. α rw (-)and α rs (-) represent the reduction coefficients for water stress and salt stress, respectively; strs t This indicates the temperature stress coefficient (-).

[0176] The following two specific embodiments will be used to describe the dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid groundwater shallow-buried irrigation areas provided by the present invention.

[0177] S5. Based on the simulation results of S1-S4, the interaction between soil water, groundwater and surface water in the irrigation area to be simulated is coupled and simulated using the spatiotemporal coupling method.

[0178] In one embodiment, S5 includes:

[0179] S501. The unsaturated zone soil water and salt transport process and groundwater dynamics of the irrigation area to be simulated are solved by sequential coupling.

[0180] S502. The groundwater dynamics and surface water flow confluence evolution process of the irrigation area to be simulated are solved using an iterative coupling method until the preset convergence criterion is met. The expression for the preset convergence criterion is:

[0181] ,

[0182] In the expression for the predefined convergence criterion, Q AQii This represents the aquifer-residence exchange rate (m³) of the current external iteration of the surface water simulation for receptacle ii. 3 d -1 ); Q MFii This represents the aquifer-residence exchange rate (m) of the current external iteration of the groundwater simulation for receptacle ii. 3 d-1 ); f AQmax This indicates the maximum allowable relative difference in aquifer-river section exchange rate across any river section. nr This represents the number of river segments in the surface water dataset.

[0183] The time steps required to solve for the unsaturated zone soil water and salt transport processes and the confluence and evolution of surface water flows are often much shorter than those required to solve for groundwater dynamics. Therefore, this embodiment uses different time steps to solve for soil water flow, groundwater flow, and surface water flow. For example... Figure 2 As shown, groundwater is simulated with days as the time step. When solving the Richards equation and the one-dimensional diffusion wave equation, the calculation day is subdivided into multiple time steps.

[0184] This embodiment employs a sequential coupling method to solve for soil and groundwater flows: When calculating soil water dynamics, it is assumed that the pressure head at the lower boundary of the soil remains constant on any given day. After the calculation of the unsaturated zone process, the daily cumulative net vertical recharge of each HRU is "mapped" to the RCH subroutine package in the groundwater calculation, serving as the source and sink terms for its respective grid (positive or negative values ​​can be considered as recharge or groundwater evaporation, respectively). Surface runoff and low-level drainage in each sub-basin are "mapped" to the inlet of its superior drainage ditch as source and sink terms.

[0185] This embodiment employs an iterative coupling approach to solve for groundwater flow and surface water flow: the surface water flow solution begins with the boundary conditions formed by the groundwater head the previous day. After convergence at the last time step in the diffusion wave equation solution, the groundwater system is solved using new boundary conditions formed by the surface water level. Since the iterations of groundwater level and surface water level always lag each other by one day, to further ensure the convergence between the surface water and groundwater systems, the above process is repeated continuously, even if the solutions to the groundwater equation and the diffusion wave equation have already met their respective convergence criteria, until the user-defined aquifer-river section convergence criterion (preset convergence criterion) is reached.

[0186] When modeling arid irrigation areas with shallow groundwater, a sufficiently deep soil profile needs to be established so that its bottom remains below the groundwater level. The daily updated groundwater depth is used to determine the soil lower boundary conditions for the next simulation day. After updating the groundwater depth, because the matric potential of the soil profile needs to match the updated groundwater depth, the above coupling method can cause sudden inflow or outflow fluxes (pseudo-fluxes) at the bottom of the soil profile, leading to oscillations in the simulation results. Therefore, in this embodiment, the pressure head of the soil profile for the simulation day is adjusted by simultaneously considering the daily net vertical recharge of the unsaturated zone and the updated groundwater depth, thereby eliminating pseudo-fluxes.

[0187] S503. In the spatial dimension, the interaction between soil water, groundwater and surface water in the irrigation area to be simulated is coupled and simulated using mapping expressions.

[0188] The mapping expression is:

[0189] , (Formula 1)

[0190] (Formula 2)

[0191] (Formula 3)

[0192] In the mapping expression, RECH grid This represents the daily cumulative net vertical recharge (m) for each groundwater grid in the groundwater simulation. nDHRU This indicates the number of DHRUs that overlap with the groundwater grid. DHRUs represent independent sub-hydrological response units decomposed by HRUs. CS DHRU,p and The soil bottom flux, channel leakage and drainage (mm) are respectively the independent sub-hydrological response units. A overlap Represents the overlapping area (m 2 ); A grid The area of ​​the groundwater grid (m²) 2 ), GWD grid,p Indicates the groundwater depth (m) of each groundwater grid; nGRID Indicates the number of DHRUs that overlap with the groundwater grid; A DHRU,p and A HRU Represent the areas (m²) of DHRU and HRU respectively. 2 ); GWD DHRU,p and GWD HRU These represent the groundwater depth (m) for DHRU and HRU, respectively.

[0193] See Figure 3In this embodiment, the spatial discretization of surface water flow is consistent with that of groundwater flow, but the spatial discretization scheme of the unsaturated zone (i.e., HRU) differs from that of groundwater and surface water (i.e., grids and river segments / groups). Therefore, the interaction between different water systems needs to be "mapped" through the positional relationships between HRUs and groundwater grids, sub-basins and river segments / groups. When HRUs are not geographically adjacent, they are first decomposed into independent DHRUs. The area overlap rate between DHRUs and groundwater grids can be calculated in ArcGIS and then a file is generated for model input. The net vertical flux at the bottom of the soil for each DHRU is the same as that of its HRU. Then, the flux is "mapped" to the overlapping groundwater grids according to the percentage of area occupied by the DHRU within the groundwater grid (see Equation 1 in the mapping expression).

[0194] A two-dimensional array (ASCII code) matching the rows and columns of the groundwater grid is used for spatial positioning to establish connections between sub-basins and river segments / groups. In this array, the value at the river inlet grid location is assigned the corresponding sub-basin number, thus "mapping" the surface water source and sink (surface runoff and agricultural drainage) generated within each sub-basin to the corresponding river segment / group inlet. After each day's groundwater and surface water simulation, the updated groundwater depth within the grid is "mapped" to the DHRU based on the percentage of the groundwater grid area to its corresponding DHRU area (see Equation 2 in the mapping expression). Then, based on the percentage of the DHRU area to its corresponding HRU area, it is "mapped" to the HRU (see Equation 3 in the mapping expression).

[0195] Example 1

[0196] Utilizing the experimental results from 2012 and 2013 in the Yangchangqu Experimental Area of ​​the Hetao Irrigation District ( Figure 4 The invention was tested by measuring soil moisture content and salinity, crop leaf area index and groundwater depth at four observation points (corn, sunflower, watermelon and natural land) in different soil layers (0-10, 10-20, 20-40, 40-60 and 60-80 cm).

[0197] Based on the location of the canal system and drainage ditches in the Yangchangqu experimental area, it was considered an independent sub-watershed and divided into 68 HRUs (High-Rise Units) according to land use, soil type, and slope. The simulated soil water and salt transport profile was set at 0–300 cm below the surface, uniformly divided into 300 nodes with a node spacing of 1 cm. The simulation period was from early May to late September each year, covering the entire growth period of maize, sunflower, and watermelon. The upper boundary condition for water flow was determined by actual evaporation, irrigation, precipitation, or field waterlogging, while the lower boundary condition was determined by the pressure head derived from the daily updated groundwater depth. The upper and lower boundary conditions for solute transport were based on the measured salt concentrations of irrigation water and groundwater (0.5 and 2.0 g / L, respectively). -1 The initial water head of the soil profile was determined by the hydrostatic equilibrium of the initial groundwater level, and the initial salt concentration was obtained by kriging interpolation of the observed values. The maximum root depths of maize, sunflower, wheat, watermelon, and tamarisk were set to 90, 80, 100, 150, and 90 cm, respectively.

[0198] The groundwater system is vertically divided into a single layer, 30 m thick, and horizontally divided into a uniform 10 m × 10 m grid, consisting of 33 columns and 66 rows. Surface elevation is determined through interpolation of observational data. The aquifer is assumed to be horizontally isotropic, and a permeability coefficient of 10 md is set. -1 The vertical permeability coefficient is one-tenth of the horizontal value, and the water storage coefficient is 1×10⁻⁶. -6 m -1 The water yield of the simulated layer at the start of a new day was calculated using Equation 6. The initial groundwater head for each grid cell was obtained by interpolating the observation data from the first day of the simulation. The diffusion wave equation was used to calculate the irrigation ditch on the southeast side of the study area, and other boundaries were defined as zero flux boundaries.

[0199] Based on the groundwater grid, the agricultural ditch on the southeast side of the study area was divided into 94 segments, and further subdivided into 9 segment groups according to the land use type near the ditch. The cross-sectional shape of these segments is defined as trapezoidal, with a base width of 1 m, a base elevation of 1037.3 m, a slope of 1:1, and a Manning roughness coefficient of 0.045 sm. -1 / 3 The riverbed has a hydraulic conductivity of 2 m. 2 d -1 Since the inflow from the upstream of the study area is not considered, the boundary conditions of the upstream of the agricultural ditch are as follows: Q inlet = Q ( t )=0, downstream boundary condition is Q outlet = Q ( h ), outflow rate ( Q outlet) and river level ( h The relationship was calculated using the Manning formula. Since the irrigation ditch is dry at the beginning of the growing season, the initial water level is the elevation of the riverbed. Furthermore, minor ditches within the study area are not considered.

[0200] Simulation results show that this invention can accurately capture the dynamic changes in water and salt content of stratified soil and its response to environmental changes during the simulation process. Figure 5 For example, after irrigation, soil moisture content increases rapidly, and the salt concentration in the upper layer decreases significantly, while the salt concentration in the deeper layers shows little change. After irrigation or rainfall ends, due to water consumption and redistribution, soil moisture content gradually decreases, and salts accumulate again in the soil surface. When groundwater levels are shallow during the growing season, due to capillary action, soil moisture content in fields that were not irrigated during a particular water inflow remains at a relatively high level. Figure 5 This invention can accurately capture the spatiotemporal dynamic changes of groundwater, and the simulated values ​​show good consistency with the measured values. Figure 6 , Figure 7 Although the shallow groundwater system in the study area is complex and the soil planting structure is fragmented, this invention can still accurately describe the interaction between groundwater and the unsaturated zone in both time and space. The simulation results of groundwater demonstrate the invention's ability to simulate surface water flow and its interaction with groundwater. The simulation of leaf area index of maize and sunflower in the study area also shows a high degree of agreement with the measured values. Figure 8 This demonstrates that the present invention can reasonably simulate crop growth.

[0201] In Example 1, the present invention exhibits satisfactory simulation performance and accuracy, with high numerical stability and the ability to effectively characterize the spatiotemporal dynamics of soil water and salt, shallow groundwater, surface water, and crop growth, as well as their interactions, within shallowly buried arid agricultural watersheds.

[0202] Example 2

[0203] Utilizing the opportunities presented by the 2021 research in the Hetao Irrigation District ( Figure 4 The model was validated and applied at the regional scale by measuring soil moisture content, salt concentration (0-10, 10-20, 20-40, 40-60 and 60-80 cm), groundwater depth and drainage flow at 22 soil observation points, 12 observation wells and 6 water-crossing sections set up along the central and southern tributaries.

[0204] Based on the canal and drainage network layout of the Jiyuan study area, it was divided into 42 sub-basins, and further subdivided into 2307 HRUs according to land use, soil type, and slope. The soil profile of each HRU was discretized into 60 layers, with a spacing of 5 cm between each layer. The upper and lower boundary conditions, initial conditions, and plant growth parameters for soil water and salt transport in the Jiyuan study area were similar to those in the Yangchang Canal experimental area (see Example 1). Horizontally, a uniform 100 m × 100 m grid was used to divide the groundwater system into 109 columns and 133 rows. Vertically, the groundwater system was discretized into three layers, each 10 m thick. A zero-flux boundary was established on the southwest side of the Jiyuan study area, and a flux boundary condition was set on the southeast side. A one-dimensional diffusion wave equation was used to model the drainage ditches in the central and eastern parts of the study area, dividing them into 819 segments, which were further grouped into 49 segment groups based on geographical location. The upstream boundary condition of the drainage ditches was... Q inlet =Q( t =0, downstream boundary conditions at the exit of the study area ( Q outlet = Q ( h The Manning formula was used for estimation, and the drainage volume of the agricultural ditches in the study area was calculated using the Hooghoudt equation.

[0205] Simulation results show that the present invention has high accuracy in simulating soil moisture and salinity concentrations at soil observation points (including typical farmland and natural land) on a larger scale. Figure 9 And efficiency. The simulated groundwater level matches the observed values ​​well. Figure 10 Although the simulated values ​​for some wells (such as Well 2 and Well 11) were lower than the observed values, the simulated fluctuation trends showed good consistency with the observed data, and the results were acceptable. For the simulation of surface water flow, this invention also performed excellently in simulating the drainage volume and water level of the two main drainage ditches in the study area, accurately capturing the changes in drainage flow caused by groundwater fluctuations during each irrigation period. Figure 11 In particular, the simulation results for the B1-B4 observation sections located in the central drainage ditch (which only receive drainage from within the study area) are in high agreement with the observed flow rates.

[0206] Example 2 further verifies the high accuracy of the present invention in simulating soil water and salt transport, groundwater fluctuations, crop growth, and their interactions on a larger regional scale, and provides a detailed evaluation of the accuracy and applicability of the surface water flow module in complex multi-stage drainage systems. Furthermore, this example requires only approximately 18 minutes of computation time on a computer configured with a 16-core 2.90GHz CPU, demonstrating the high computational efficiency of the present invention.

[0207] This invention provides a dynamic coupling simulation method, system, equipment, and medium applicable to the transformation of four water systems and vegetation growth in arid, shallowly buried groundwater irrigation areas. It accurately simulates the dynamics of soil water (salt), groundwater, and surface water using kinetic equations and employs an improved crop growth model to simulate vegetation growth. Furthermore, it relies on an efficient spatiotemporal coupling method to rationally describe the complex interactions of various water systems in time and space, precisely simulating the transformation of four water systems and vegetation growth in arid, shallowly buried groundwater irrigation areas. This invention reasonably considers the impact of various agronomic and land management measures (such as surface cover, earthen embankments, canals, and drainage ditches) on water transformation in arid irrigation areas, while also considering the impact of soil salinization caused by shallow groundwater burial on plant root water absorption and growth. This invention has significant advantages in simulation accuracy and computational efficiency, is simple and convenient to operate, and provides clear results output, making it highly practical.

[0208] The following describes the dynamic coupling simulation system for the transformation of four waters and vegetation growth in arid groundwater shallow-buried irrigation areas provided by this invention. The dynamic coupling simulation system for the transformation of four waters and vegetation growth in arid groundwater shallow-buried irrigation areas described below can be referred to in correspondence with the dynamic coupling simulation method for the transformation of four waters and vegetation growth in arid groundwater shallow-buried irrigation areas described above.

[0209] See Figure 12 This invention provides a dynamic coupling simulation system for the transformation of four types of water and vegetation growth in arid, shallowly buried groundwater irrigation areas, comprising:

[0210] The data acquisition module is used to execute S0: acquire the cross-sectional dimensions, roughness, and geographical location data of the irrigation canals and drainage ditches in the irrigation area to be simulated; soil classification, soil moisture content, and salinity data; planting structure data; groundwater level data; and surface water flow (or water level) data.

[0211] The soil water simulation module is used to perform S1: Based on the geographical location of the irrigation canals and drainage ditches in the irrigation area to be simulated, the irrigation area to be simulated is divided into several sub-basins, and the several sub-basins are divided into several hydrological response units (HRUs) according to land type and planting structure data, and the unsaturated soil water and salt transport process of each hydrological response unit is simulated.

[0212] The groundwater simulation module is used to execute S2: Based on the initial water level data of the irrigation area to be simulated, and combined with the impact of channel leakage, drainage ditch and soil water on groundwater, the improved groundwater flow model is used to simulate the groundwater dynamics of the irrigation area to be simulated.

[0213] The surface water simulation module is used to execute S3: based on the surface water cross-sectional dimensions and roughness of the irrigation area to be simulated, combined with the surface runoff, low-level drainage volume and groundwater in the sub-basin, the confluence and evolution process of surface water flow in the irrigation area to be simulated is simulated.

[0214] The crop growth simulation module is used to execute S4: using an improved crop growth model to simulate the crop growth in the irrigation area to be simulated, and coupling it with soil water and salt simulation to obtain a dynamic coupling simulation model of the four water transformations and vegetation growth in the irrigation area to be simulated.

[0215] The coupled simulation module is used to execute S5: Based on the simulation results of S1-S4, an efficient spatiotemporal coupling method is proposed and used to couple the interaction between soil water, groundwater and surface water in the irrigation area to be simulated.

[0216] Figure 13 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 13 As shown, the electronic device may include a processor 810, a communication interface 820, a memory 830, and a communication bus 840, wherein the processor 810, the communication interface 820, and the memory 830 communicate with each other via the communication bus 840. The processor 810 can call logical instructions in the memory 830 to execute the dynamic coupling simulation method for the transformation of four types of water and vegetation growth in shallowly buried groundwater irrigation areas as described above.

[0217] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0218] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program, the computer program being stored on a non-transitory computer-readable storage medium, and when the computer program is executed by a processor, the computer is able to execute the dynamic coupling simulation method for the transformation of four waters and vegetation growth in shallow buried irrigation areas of arid groundwater as described above.

[0219] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the dynamic coupling simulation method for the transformation of four waters and vegetation growth in shallow buried irrigation areas of arid groundwater as described in any of the preceding claims.

[0220] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0221] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0222] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamic coupling simulation method for the transformation of four types of water and vegetation growth in arid, shallowly buried groundwater irrigation areas, characterized in that, include: S0. Obtain channel drainage data, soil water data, groundwater data, surface water data, and planting structure data of the irrigation area to be simulated; S1. Based on the channel drainage data and planting structure data of the irrigation area to be simulated, the irrigation area to be simulated is divided into several sub-basins, and each sub-basin is further divided into several hydrological response units according to land type and planting structure. The unsaturated soil water and salt transport process of each hydrological response unit is simulated. S2. Based on the groundwater data of the irrigation area to be simulated, and combined with the impact of channel leakage, drainage ditch and soil water on groundwater, the groundwater dynamics of the irrigation area to be simulated are simulated using an improved groundwater flow model. S3. Based on the surface water data of the irrigation area to be simulated, and combined with the surface runoff, low-level drainage volume and groundwater in the sub-basin, the confluence and evolution process of surface water flow in the irrigation area to be simulated is simulated. S4. The improved crop growth model was used to simulate the crop growth in the irrigation area to be simulated, and it was closely coupled with the soil water and salt simulation process to obtain the dynamic coupling simulation model of the four water transformations and vegetation growth in the irrigation area to be simulated. S5. Based on the simulation results of S1-S4, the interaction between soil water, groundwater and surface water in the irrigation area to be simulated is coupled and simulated using the spatiotemporal coupling method.

2. The dynamic coupling simulation method for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas according to claim 1, characterized in that, S1 includes: The vertical one-dimensional flow motion of each hydrological response unit in several hydrological response units was simulated using the vertical soil hydrodynamic equation. The solute transport process in the soil of each of several hydrological response units was simulated using solute transport equations. The vertical soil hydrodynamic equation is as follows: ， In the vertical soil hydrodynamic equation, θ Indicates the soil volumetric moisture content; t Indicates time; z Indicates the depth below the ground; S a Indicates soil water source collection; h S Indicates soil pressure head; K ( h S () indicates the soil's hydraulic conductivity; The solute transport equation is: ， In the solute transport equation, θ Indicates the soil volumetric moisture content; ρ b Indicates the dry bulk density of the soil; q Indicates the soil water flux between nodes; c Indicates soil salinity concentration; z Indicates the depth below the ground; D dif Indicates the solute diffusion coefficient; D dis Indicates the hydrodynamic dispersion length; Q This indicates the amount of solute adsorbed by the soil. S s This indicates a solute source / sink term.

3. The dynamic coupling simulation method for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas according to claim 2, characterized in that, S2 include: The water yield of the irrigation district to be simulated is updated using a variable water yield formula. The leakage rate of low-level channels in the irrigation area to be simulated is obtained using the channel leakage rate formula. By combining the updated water supply, the channel leakage of the low-level channels in the irrigation area to be simulated, and the exchange of soil water and groundwater obtained through S1, the groundwater dynamics of the irrigation area to be simulated are simulated using an improved groundwater flow model through a three-dimensional groundwater flow motion equation. The formula for variable feedwater concentration is: ， In the formula for variable water yield, S y This indicates the updated water supply level; θ s , θ r These represent saturated moisture content and residual moisture content, respectively. d Indicates the depth of groundwater; α and n Represents empirical parameters of shape; d 0 represents the critical value for groundwater depth. S ycons express exist d The specific yield above 0 is assumed to be a conventional constant; The formula for channel leakage is: ， In the formula for channel leakage, CS k This represents the channel leakage within the k-th hydrological response unit; K c,sat This indicates the effective saturated hydraulic conductivity of the canal bottom; X The wetted period is estimated based on the irrigation water volume given in each hydrological response unit. L c,k This represents the channel length within the k-th hydrological response unit; A k This represents the area of ​​the k-th hydrological response unit; The three-dimensional equations for groundwater flow are: ， In the three-dimensional equations of groundwater flow, K xx , K yy and K zz These represent the hydraulic conductivity along the x, y, and z coordinate axes, respectively; h Indicates water head; t Indicates time; W Indicates source and sink terms, representing the amount of water flowing into or out of a unit volume of aquifer per unit time; S y and S s These represent the specific yield and storage coefficient of the porous medium, respectively.

4. The dynamic coupling simulation method for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas according to claim 3, characterized in that, S3 include: The Hooghoudt equation was used to obtain the low-level drainage volume in the sub-basin. The surface runoff, drainage volume of low-level drainage ditches, and aquifer-river section exchange volume obtained through S2 within the sub-basin are combined to simulate the surface water flow in the simulated irrigation area. The confluence and evolution process of surface water flow in the simulated irrigation area is simulated using the one-dimensional diffusion wave equation. The Hooghoudt equation is as follows: ， ， ， In the Hooghoudt equation, Q g This indicates the amount of water discharged, where, Q g,hru and Q g,sub These represent the drainage volume of the hydrological response unit and the sub-basin, respectively. GWD Indicates the depth of groundwater; j Indicates a simulated date; K e Indicates lateral hydrotropism; m m Indicates the groundwater surface drainage elevation; d e Indicates equivalent depth; d d Indicates the depth of the impermeable layer; L d Indicates the spacing between drainage ditches; nHRU This indicates the number of hydrological response units in a sub-basin; A HRU Indicates the area of ​​the hydrological response unit; The equation for a one-dimensional diffused wave is: ， In the one-dimensional diffusion wave equation, V Represents the volume of any control volume; t Indicates time; nconn Indicates the number of connections to the control unit; A Represents the cross-sectional area; H Indicates the surface water level above the reference level; x Represents spatial coordinates; Q LAT This refers to the volumetric flow rate of surface runoff and low-level drainage within a sub-basin. Q PR Indicates rainfall amount; Q EV Indicates the amount of evaporation; Q AQ This indicates the amount of water exchanged between the aquifer and the river section. D Mi This represents a nonlinear diffusion term.

5. The dynamic coupling simulation method for water transformation and vegetation growth in shallowly buried irrigation areas with arid groundwater, as described in claim 4, is characterized in that, S4 include: Using an improved crop growth model, the actual root water uptake and plant growth regulators of crops in the simulated irrigation area were obtained through expressions for potential root water uptake, actual root water uptake, actual transpiration rate, and plant growth regulators. Based on the actual root water uptake and plant growth regulators of crops in the irrigation area to be simulated, the growth of crops in the irrigation area to be simulated is simulated and coupled with soil water and salt simulation. The expression for potential root water absorption is as follows: ， In the expression for potential root water uptake, S p This represents the potential root water uptake at a specific node z; D root Indicates the deepest root depth on that day; T p Indicates the potential transpiration rate of plants unaffected by water and salt stress; I root This represents the root length density at a specific node at depth z. The expression for actual root water absorption is: ， In the actual root water absorption expression, S a This represents the actual water absorption by the roots at a specific node z; α rw and α rs These represent the reduction coefficients for water stress and salt stress, respectively. The actual transpiration rate is expressed as: ， In the actual transpiration rate expression, T a Indicates the actual transpiration rate; S a This represents the actual water absorption by the roots at a specific node z; D root Indicates the deepest root depth on that day; The expression for plant growth regulators is: ， In the expression of plant growth regulators, γ reg This refers to plant growth regulators, which are a portion of the potential growth that can be achieved within a given day. α rw and α rs These represent the reduction coefficients for water stress and salt stress, respectively. strs t This represents the temperature stress coefficient.

6. The dynamic coupling simulation method for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas according to claim 5, characterized in that, S5 include: In the time dimension, the interaction between soil water, groundwater and surface water in the irrigation area to be simulated is coupled by combining sequential coupling and iterative coupling. In the spatial dimension, the interaction between soil water, groundwater, and surface water in the irrigation area to be simulated is coupled and simulated using mapping expressions. The mapping expression is: ， ， ， In the mapping expression, RECH grid This represents the daily cumulative net vertical recharge for each groundwater grid in the groundwater simulation. nDHRU This indicates the number of DHRUs that overlap with the groundwater grid. DHRUs represent independent sub-hydrological response units decomposed by HRUs. CS DHRU,p and These represent the soil bottom flux, channel leakage, and drainage of the independent sub-hydrological response units, respectively. A overlap Indicates the overlapping area; A grid This indicates the area of ​​the groundwater grid. GWD grid，p This indicates the groundwater depth of each groundwater grid. nGRID Indicates the number of DHRUs that overlap with the groundwater grid; A DHRU,P and A HRU These represent the areas of the DHRU and HRU, respectively. GWD DHRU,P and GWD HRU These represent the groundwater depths of DHRU and HRU, respectively.

7. The dynamic coupling simulation method for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas according to claim 6, characterized in that, The simulation, which combines sequential and iterative coupling in the temporal dimension, simulates the interactions between soil water, groundwater, and surface water in the irrigation district to be simulated. This includes: The unsaturated zone soil water and salt transport processes and groundwater dynamics of the irrigation area to be simulated were solved by sequential coupling. An iterative coupling approach is used to solve the dynamics of groundwater and the confluence evolution of surface water in the irrigation area to be simulated until the preset convergence criteria are met. The expression for the preset convergence criterion is: ， In the expression for the predefined convergence criterion, Q AQii This represents the aquifer-residence exchange volume of the current external iteration of the surface water simulation for receptacle ii. Q MFii This represents the aquifer-residence exchange volume of residence ii in the current external iteration of the groundwater simulation. f AQmax This indicates the maximum allowable relative difference in aquifer-river section exchange rate across any river section. nr This represents the number of river segments in the surface water dataset.

8. A dynamic coupling simulation system for water transformation and vegetation growth in arid, shallowly buried groundwater irrigation areas, characterized in that, include: The data acquisition module is used to execute S0: acquire channel drainage data, soil water data, groundwater data, surface water data, and planting structure data of the irrigation area to be simulated; The soil water simulation module is used to perform S1: Based on the channel drainage data and planting structure data of the irrigation area to be simulated, the irrigation area to be simulated is divided into several sub-basins, and each sub-basin is divided into several hydrological response units according to land type and planting structure, and the unsaturated zone soil water and salt transport process of each hydrological response unit is simulated. The groundwater simulation module is used to execute S2: Based on the groundwater data of the irrigation area to be simulated, and combined with the impact of channel leakage, drainage ditch and soil water on groundwater, the improved groundwater flow model is used to simulate the groundwater dynamics of the irrigation area to be simulated. The surface water simulation module is used to execute S3: based on the surface water data of the irrigation area to be simulated, combined with the surface runoff, low-level drainage volume and groundwater in the sub-basin, the confluence and evolution process of surface water flow in the irrigation area to be simulated is simulated. The crop growth simulation module is used to execute S4: using an improved crop growth model to simulate the crop growth in the irrigation area to be simulated, and tightly coupling it with the soil water and salt simulation process to obtain a dynamic coupling simulation model of the four water transformations and vegetation growth in the irrigation area to be simulated. The coupled simulation module is used to execute S5: based on the simulation results of S1-S4, it uses the spatiotemporal coupling method to couple the interaction between soil water, groundwater and surface water in the irrigation area to be simulated.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the dynamic coupling simulation method for the transformation of four waters and vegetation growth in shallow buried irrigation areas with arid groundwater as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the dynamic coupling simulation method for the transformation of four waters and vegetation growth in shallow buried irrigation areas with arid groundwater as described in any one of claims 1 to 7.

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