CN-121980854-A - Groundwater numerical simulation method for coupling vegetation ecology

CN121980854ACN 121980854 ACN121980854 ACN 121980854ACN-121980854-A

Abstract

The invention relates to the technical field of groundwater simulation, in particular to a coupled vegetation ecology groundwater numerical simulation method. The method realizes bidirectional coupling between groundwater and vegetation ecology through iteration, and concretely comprises inversion of vegetation coverage based on groundwater burial depth, inversion of actual evaporation based on groundwater burial depth and vegetation coverage, and updating of net supply of a groundwater model based on evaporation until convergence. The method replaces a complex physical model by establishing a statistical function relation, and corrects the water level of the drain and overflow cells in iteration to ensure stable calculation.

Inventors

HAN PENGFEI
WANG XUSHENG
BAI TAIYA
ZHANG ZHIYUAN

Assignees

中国地质大学（北京）

Dates

Publication Date: 20260505
Application Date: 20260108

Claims (6)

1. The underground water numerical simulation method for coupling vegetation ecology is characterized by comprising the following steps of: step S1, geographical information, groundwater hydrologic characteristics and environmental data of a target area are obtained, and a steady flow MODIFLOW groundwater model of the target area is constructed based on the obtained data; s2, acquiring vegetation coverage remote sensing products, underground water buried grid data and actual evapotranspiration grid data of the same time period and the same spatial resolution of a target area, and performing spatial matching to form a standardized data set; S3, constructing and calibrating a vegetation coverage inversion model by taking the underground water burial depth as an independent variable and the vegetation coverage as a dependent variable based on the standardized data set; S4, based on the standardized data set, constructing and calibrating an actual evapotranspiration inversion model by taking the underground water burial depth and the vegetation coverage as independent variables and taking the actual evapotranspiration as dependent variables; S5, calculating an initial groundwater level field and an initial net compensation amount of the iterative model according to a simulation result of the MODIOW groundwater model; S6, copying the MODIflow groundwater model, deleting a diving evaporation module in the MODIflow groundwater model to obtain an iteration model for subsequent iteration calculation, and inputting an initial groundwater level field and an initial net replenishment quantity into the iteration model; S7, starting iterative computation, running a current iterative model, and obtaining a ground water level field output by the current iterative model; s8, correcting the water level of all overflow cells in the submerged aquifer water level field to the height of an aquifer top plate of the cell based on the underground water level field, and filling the water level value of all drain cells in the submerged aquifer water level field by adopting an interpolation method, so that the corrected submerged aquifer water level field is obtained; Step S9, obtaining a ground water buried depth field by using the corrected water level field of the submerged aquifer with the ground surface height Cheng Jianqu, and assigning all negative values in the ground water buried depth field to be 0, so as to ensure that the ground water level does not exceed the ground surface and obtain the ground water buried depth field of the current iteration; Step S10, inversion calculation is carried out on a vegetation coverage distribution field of the current iteration based on the vegetation coverage inversion model and the underground water burial depth field of the current iteration; S11, inputting the underground water buried depth field of the current iteration and the vegetation coverage distribution field of the current iteration into the actual evapotranspiration inversion model, and performing inversion calculation to obtain the actual evapotranspiration field of the current iteration; Step S12, calculating the net replenishment quantity of the iteration model at the next iteration according to the actual evaporation field of the current iteration, taking the corrected diving aquifer water level field calculated by the iteration model at the current iteration as the initial water level field of the next iteration, returning to the step S7 according to the net replenishment quantity of the next iteration, and carrying out iterative calculation with the updated parameters until the iteration model reaches a preset iteration ending condition; and S13, outputting the underground water level field, the inverted vegetation coverage field and the actual evaporation field which are calculated by the simulation of the iterative model after the iteration model is finished after the iteration model reaches the preset iteration finishing condition.
2. The method according to claim 1, wherein the step S1 comprises: Constructing a MODIOWW model; Obtaining boundary conditions, mesh subdivision, aquifer structure and permeability coefficient of a target area, and inputting the boundary conditions, mesh subdivision, aquifer structure and permeability coefficient into a MODIFLOW model; Setting the groundwater flowing process, the initial water level condition, the solver and the convergence criterion parameters of the MODIflow model, and completing the construction of the steady flow MODIflow groundwater model of the target area.
3. The method according to claim 2, wherein said step S5 comprises: correcting the water level obtained by simulating the MODIflow groundwater model to obtain the initial water level of the iterative model, wherein the correction comprises the steps of interpolating and filling the water level of the drainage cells and correcting the water level of the overflow cells to the top plate elevation of the aquifer; and subtracting the diving evaporation amount from the net supply amount obtained by simulating the MODIOW groundwater model through a grid computing tool to obtain the initial net supply amount of the iterative model.
4. A method according to claim 3, wherein said step S12 comprises: Calculating the net supply quantity of the next iteration of the iteration model according to the inverted actual evaporation field, the current net supply quantity and the relaxation iteration coefficient; taking the corrected diving aquifer water level field calculated by the iteration model at present as an initial water level field of the next iteration; And returning to the step S7, and performing iterative computation with the updated parameters until a preset iteration ending condition is reached.
5. The method according to claim 4, wherein the returning to step S7 for iterative calculation with updated parameters includes: before the next iterative computation is carried out on the iterative model, judging whether the current iterative computation reaches the preset iterative times or whether the computation result meets the convergence condition; and stopping iterative computation if the current iterative computation reaches the preset iterative times or the computation result meets the convergence condition.
6. The method of claim 5, wherein the convergence condition comprises: in all non-drainage cells, whether the maximum value of the absolute value of the water level change of two adjacent iterations is smaller than a first set threshold value or not; The relative change rates of the number of the drainage cells, the number of the overflow cells, the number of the cells overflowed by the drainage change and the number of the cells overflowed by the drainage change are all smaller than a second set threshold value.

Description

Groundwater numerical simulation method for coupling vegetation ecology Technical Field The invention relates to the technical field of groundwater simulation, in particular to a coupled vegetation ecology groundwater numerical simulation method. Background Groundwater numerical modeling is a technique that utilizes mathematical models and numerical methods to model groundwater flow and interactions of groundwater with the surrounding environment. The method is characterized in that a numerical method (finite difference method or finite element method) is adopted to solve a groundwater flow control equation based on Darcy's law, so that the dynamic behavior of a groundwater system is simulated and analyzed. MODFLOW is one of the most commonly used groundwater flow numerical simulation software at present based on its flexibility and wide application. The MODIflow can effectively simulate the flowing process under the conditions of stable groundwater and unstable flow, and can simulate the flowing process by combining a plurality of factors such as atmospheric precipitation, soil, river and the like. However, there is still a large lifting space for the coupling simulation of groundwater and vegetation. In arid areas, vegetation is critical to the function of groundwater hydrologic cycle. On the one hand, the groundwater in drought period is a stable water source for deep-rooted plants, and on the other hand, the change of vegetation coverage can influence land evapotranspiration, thereby indirectly influencing the net supply amount of the groundwater. Therefore, knowing the interaction between groundwater and vegetation is of great importance to the rational management of water resources and ecological restoration in arid regions. Although interactions between groundwater and vegetation in arid regions are not negligible, most groundwater-vegetation coupling models today focus mainly on unidirectional coupling, i.e. only consider the effect of groundwater burial depth on vegetation, for example, using an exponential model or a Gamma function model to describe the response of vegetation coverage, community diversity to groundwater level changes. The unidirectional coupling model ignores the feedback effect of vegetation on groundwater, which may cause deviation of model prediction and limit the accuracy and applicability of the model in an ecological hydrologic system. Disclosure of Invention Therefore, the present invention is directed to a method for simulating the groundwater values coupled to vegetation ecology, so as to overcome the problems of the prior art. In order to achieve the above purpose, the invention adopts the following technical scheme: the application provides a coupled vegetation ecological groundwater numerical simulation method, which comprises the following steps: step S1, geographical information, groundwater hydrologic characteristics and environmental data of a target area are obtained, and a steady flow MODIFLOW groundwater model of the target area is constructed based on the obtained data; s2, acquiring vegetation coverage remote sensing products, underground water buried grid data and actual evapotranspiration grid data of the same time period and the same spatial resolution of a target area, and performing spatial matching to form a standardized data set; S3, constructing and calibrating a vegetation coverage inversion model by taking the underground water burial depth as an independent variable and the vegetation coverage as a dependent variable based on the standardized data set; S4, based on the standardized data set, constructing and calibrating an actual evapotranspiration inversion model by taking the underground water burial depth and the vegetation coverage as independent variables and taking the actual evapotranspiration as dependent variables; S5, calculating an initial groundwater level field and an initial net compensation amount of the iterative model according to a simulation result of the MODIOW groundwater model; S6, copying the MODIflow groundwater model, deleting a diving evaporation module in the MODIflow groundwater model to obtain an iteration model for subsequent iteration calculation, and inputting an initial groundwater level field and an initial net replenishment quantity into the iteration model; S7, starting iterative computation, running a current iterative model, and obtaining a ground water level field output by the current iterative model; s8, correcting the water level of all overflow cells in the submerged aquifer water level field to the height of an aquifer top plate of the cell based on the underground water level field, and filling the water level value of all drain cells in the submerged aquifer water level field by adopting an interpolation method, so that the corrected submerged aquifer water level field is obtained; Step S9, obtaining a ground water buried depth field by using the corrected water level field of the submerged aquifer with