Underground water supply process analysis method

Abstract

The invention discloses a groundwater supply process analysis method, and relates to the technical field of groundwater calculation. Obtaining a rainfall base flow response model; the rainfall base flow response model is constructed according to a relationship among a river base flow formed by a large channel priority flow, a soil priority flow and a soil piston flow, an underground water utilization amount and a base flow of a drainage basin outlet; based on the rainfall data and the basic flow data of the research area, solving model parameters of the rainfall basic flow response model through a genetic algorithm to obtain target values of the model parameters in the rainfall basic flow response model; according to the target value, determining a water recession unit line of the large channel priority flow, the soil priority flow and the soil piston flow of the research area; the recession unit line is used for describing the groundwater supply process of the research area. The method can accurately analyze the groundwater supply process of the loess plateau area large channel priority flow, the soil priority flow and the soil piston flow.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater calculation, and particularly to a method for analyzing the groundwater recharge process. Background Art

[0002] At present, surface water resources are scarce on the Loess Plateau, and atmospheric precipitation is the main water recharge source in this area. Shallow groundwater is the main source of surface runoff on the Loess Plateau and the fresh water resources on which local residents rely for survival, and is of great significance to the sustainable development of the regional social economy. Correctly understanding the groundwater recharge process (including recharge cycle, recharge mode and its contribution) is the basis for clarifying the regional groundwater circulation mechanism and the primary prerequisite for groundwater development and utilization. However, the vadose zone soil layer on the Loess Plateau is thick (usually between 30 m and 100 m), the groundwater recharge cycle is long (ranging from several days to several decades), and the recharge modes are diverse (piston flow, preferential flow or a mixed flow of both). Accurately quantifying the process and mechanism of preferential flow and piston flow recharging groundwater is a hot frontier and challenging problem in groundwater recharge research.

[0003] In recent years, the application of stable isotope and hydrochemical tracer techniques has greatly promoted and enriched the understanding of the groundwater recharge mechanism on the Loess Plateau. Existing studies on the occurrence characteristics and mass balance of tracer elements in precipitation, deep soil water and groundwater at multiple sites can quantify the contributions of regional preferential flow and piston flow to groundwater recharge, but cannot characterize the dynamic process of groundwater recharge. In addition, on the regional scale, preferential flow is not only controlled by the pores in the soil profile, large preferential flow channels and networks such as cracks, fissures and holes in low-lying areas and runoff paths, but also affected by surface and groundwater hydrological processes. The current methods fail to effectively reflect the recharge of preferential flow in large channels on the regional scale to groundwater and cannot characterize the dynamic process of groundwater recharge.

[0004] Therefore, there is an urgent need for a method that can accurately analyze the process of large-channel preferential flow, soil preferential flow and soil piston flow recharging groundwater in the Loess Plateau region. Summary of the Invention

[0005] Based on this, it is necessary to provide a method for analyzing the groundwater recharge process in view of the above technical problems, which can accurately analyze the process of large-channel preferential flow, soil preferential flow and soil piston flow recharging groundwater in the Loess Plateau region.

[0006] The present invention adopts the following technical solutions: The present invention provides a method for analyzing the groundwater recharge process, including: Obtain a rainfall baseflow response model; the rainfall baseflow response model is constructed based on the relationship between the river baseflow volume, groundwater utilization volume, and baseflow volume at the basin outlet formed by macropore preferential flow, soil preferential flow, and soil piston flow; the river baseflow volumes formed by macropore preferential flow, soil preferential flow, and soil piston flow are determined respectively based on the differences in the lag time of groundwater recharge by macropore preferential flow, soil preferential flow, and soil piston flow and the recession unit hydrograph. Based on the rainfall data and baseflow data of the study area, solve the model parameters of the rainfall baseflow response model through a genetic algorithm to obtain the target values of the model parameters in the rainfall baseflow response model. According to the target values, determine the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow in the study area; the recession unit hydrograph is used to describe the groundwater recharge process in the study area.

[0007] Optionally, the rainfall baseflow response model is: ; Wherein, is the baseflow volume at the basin outlet, respectively represent the start time and end time of macropore preferential flow, represents the precipitation in the represents period, represents the proportion of rainfall converted into macropore preferential flow in the period, represents the potential recharge flux of soil preferential flow in the is the weight coefficient of the recession unit hydrograph formed by soil preferential flow in the respectively represent the start time and end time of soil piston flow, is the potential groundwater recharge flux of soil piston flow in the is the weight coefficient of the recession unit hydrograph formed by soil piston flow in the is the groundwater utilization volume, represents the lower incomplete Gamma function, respectively represent the Gamma function of All are model parameters of the rainfall baseflow response model.

[0008] Optionally, ; Among them, is the surface runoff during a time period, is the runoff threshold, indicating the maximum ratio; ; Among them, the subscript represents the agricultural and forestry grassland, represents the coefficient of potential recharge of soil preferential flow to groundwater, represents the land use coefficient corresponding to the agricultural and forestry grassland; represents the precipitation during a time period; ; Among them, is the coefficient of potential recharge of soil piston flow to groundwater, represents the precipitation during a time period.

[0009] Optionally, according to the target value, determine the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow, including: According to the target value, determine the weight coefficients of the recession unit hydrograph formed by macropore preferential flow in the study area, the weight coefficient of the recession unit hydrograph formed by preferential flow, and the weight coefficient of the recession unit hydrograph formed by soil piston flow; According to the weight coefficients of the recession unit hydrograph formed by macropore preferential flow in the study area, the weight coefficient of the recession unit hydrograph formed by preferential flow, and the weight coefficient of the recession unit hydrograph formed by soil piston flow, determine the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow.

[0010] Optionally, the method further includes: According to the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow in the study area, determine the time lag effect, recharge process, and cumulative recharge flux of base flow to macropore preferential flow, soil preferential flow, and piston flow.

[0011] The present invention provides a device for analyzing the groundwater recharge process, including: An acquisition module, configured to acquire a rainfall-base flow response model; the rainfall-base flow response model is constructed based on the relationship between the river base flow volume formed by macropore preferential flow, soil preferential flow, and soil piston flow, the groundwater utilization volume, and the base flow volume at the basin outlet; the river base flow volumes formed by macropore preferential flow, soil preferential flow, and soil piston flow are respectively determined based on the differences in the lag time of groundwater recharge by macropore preferential flow, soil preferential flow, and soil piston flow and the recession unit hydrograph; A solution module, configured to solve the model parameters of the rainfall baseflow response model through a genetic algorithm based on the rainfall data and baseflow data of the study area, so as to obtain the target values of the model parameters in the rainfall baseflow response model; An analysis module, configured to determine the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow in the study area according to the target values; the recession unit hydrograph is used to describe the groundwater recharge process in the study area.

[0012] The present invention provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the above groundwater recharge process analysis method is implemented.

[0013] The present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the above groundwater recharge process analysis method is implemented.

[0014] The above at least one technical solution adopted by the present invention can achieve the following beneficial effects: Based on the lag time differences in the groundwater recharge of the regional macropore preferential flow, soil preferential flow, and piston flow, combined with the recession unit hydrograph method, the river base flow formed by the macropore preferential flow, soil preferential flow, and soil piston flow is linked to the groundwater recharge and base flow, and a rainfall baseflow response model is constructed. The time series of the hydrological signal of the base flow is used to deduce the process and mechanism of the preferential flow and piston flow replenishing groundwater. Compared with the existing environmental isotope and hydrochemical tracer methods, this method overcomes the influence of the heterogeneity, scale effect of the hydrological process, and the uncertainty of tracer input on the results, breaks through the problem that it is difficult to quantitatively characterize the process of preferential flow replenishing groundwater at the regional scale, and realizes the accurate analysis of the process of the macropore preferential flow, soil preferential flow, and soil piston flow replenishing groundwater in the Loess Plateau region. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 It is a schematic flowchart of a method for analyzing the groundwater recharge process provided by the present invention; Figure 2 It is a schematic diagram of the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow, as well as the total recession unit hydrograph; Figure 3 It is a schematic diagram of a computer device for implementing the method for analyzing the groundwater recharge process provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] To make the objectives, technical solutions and advantages of the present invention more clear, the following will clearly and completely describe the technical solutions of the present invention in combination with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0017] Existing environmental isotope and hydrochemical tracing methods can quantify the contributions of preferential flow and piston flow to groundwater recharge, but the results are affected by spatial heterogeneities such as land use, soil, and vegetation, and cannot characterize the process of groundwater recharge by preferential flow and piston flow. Groundwater discharge (base flow) is the main source of river runoff in the Loess Plateau region. Existing studies have shown that rainfall has a decisive effect on it. Even if the rainfall signal becomes smooth after passing through a thick loess layer, groundwater and base flow still record and inherit the characteristics of precipitation. The characteristics of regional groundwater recharge and storage hidden in the long-term base flow signal of the basin have extremely high value for inverting the process and mechanism of groundwater recharge. Therefore, based on the lag time differences in the groundwater recharge by regional large-channel preferential flow, soil preferential flow, and piston flow, combined with the recession unit hydrograph method, the recharge of preferential flow and piston flow to groundwater is linked to the base flow to construct a rainfall-base flow response model, and the process and mechanism of groundwater recharge by preferential flow and piston flow are deduced using the time series of this hydrological signal of base flow. Compared with previous studies based on tracer elements, inferring the process (groundwater recharge) from the result (base flow) and using base flow as a proxy is a new method for analyzing the process and mechanism of groundwater recharge in the Loess Plateau.

[0018] The execution subject of the method provided in the present invention can be a server set up on a business platform, or devices such as desktop computers and laptop computers that can execute the solution of the present invention. For the convenience of description, only the server is used as the execution subject for description below.

[0019] The following will, in combination with the drawings, detail the technical solutions provided by each embodiment of the present invention.

[0020] Figure 1 It is a schematic flow diagram of a method for analyzing the groundwater recharge process in the present invention, specifically including the following steps: S101, obtain a rainfall-base flow response model; the rainfall-base flow response model is constructed based on the relationships among the river base flow, groundwater utilization, and the base flow at the basin outlet formed by large-channel preferential flow, soil preferential flow, and soil piston flow; the river base flows formed by large-channel preferential flow, soil preferential flow, and soil piston flow are determined respectively based on the lag time differences in the groundwater recharge by large-channel preferential flow, soil preferential flow, and soil piston flow and the recession unit hydrograph.

[0021] First, the initial rainfall baseflow response model can be constructed by using the relationships among the stream baseflow formed by macropore preferential flow, soil preferential flow, and soil piston flow, the groundwater utilization, and the baseflow at the watershed outlet.

[0022] The initial rainfall baseflow response model can describe the processes and mechanisms of groundwater recharge by macropore preferential flow, soil preferential flow, and piston flow. Optionally, the initial rainfall baseflow response model is: (1); Where, is the baseflow at the watershed outlet; , , are the stream baseflows formed by macropore preferential flow, soil preferential flow, and soil piston flow respectively; is the groundwater utilization. The units of the baseflow at the watershed outlet, the stream baseflows formed by macropore preferential flow, soil preferential flow, and soil piston flow, and the groundwater utilization are all millimeters.

[0023] Then, substitute the calculation formulas of the stream baseflows formed by macropore preferential flow, soil preferential flow, and soil piston flow into the initial rainfall baseflow response model to determine the rainfall baseflow response model. The calculation formulas of the stream baseflows formed by macropore preferential flow, soil preferential flow, and soil piston flow are constructed based on the differences in the lag times of groundwater recharge by macropore preferential flow, soil preferential flow, and soil piston flow and by combining the recession unit hydrograph method.

[0024] Specifically, the calculation formula for macropore preferential flow is: (2); (3); Where, respectively represent the start time and end time of macropore preferential flow, represents the precipitation in the time period, represents i the weight coefficient of the recession unit hydrograph formed by macropore preferential flow in the g time period, that is, the proportion of the macropore preferential flow generated by the rainfall in the g − i represents the lag time period number of macropore preferential flow relative to rainfall, is the surface runoff in the is the runoff threshold, represents the proportion of rainfall in the Represents the maximum ratio. Among them, the preferential flow in large channels is mainly formed by the low-lying areas within the region and the preferential flow channels in the runoff paths. When there is no surface runoff, this value is 0. As the surface runoff increases, more preferential flow channels are activated, and the proportion of rainfall converted into preferential flow in large channels increases. When the surface runoff q ri reaches the runoff threshold q th all preferential flow channels are activated, and the proportion of rainfall converted into preferential flow in large channels reaches the maximum value f max , that is, the proportion of rainfall converted into preferential flow in large channels is f max a step function.

[0025] The calculation formula for soil preferential flow is: (4); (5); Among them, respectively represent the start time and end time of soil preferential flow, represents the potential recharge flux of soil preferential flow during the is the weight coefficient of the recession unit hydrograph formed by soil preferential flow during the j time period, that is, the proportion of preferential flow generated by rainfall during the p time period in the p − j represents the lag time period number of preferential flow relative to rainfall. The subscript respectively represent farmland, forest land, and grassland, represents the potential coefficient of soil preferential flow to recharge groundwater, represents the land use coefficient corresponding to farmland, forest land, and grassland; represents the precipitation during the time period, with the unit of mm. It should be noted that is a model parameter, and its range can be determined through experiments or literature research, or a multivariate statistical mathematical relationship between it and influencing factors can be attempted to establish to reduce the workload of model parameter inversion.

[0026] The calculation formula for soil piston flow is: (6); (7); Among them, respectively represent the start time and end time of soil piston flow, is Potential recharge groundwater flux of piston flow in the soil during a period, is the weight coefficient of the recession unit hydrograph formed by piston flow in the soil during a period, that is, k the proportion of preferential flow generated by rainfall during a period in w a period, w − k represents the number of lag periods of piston flow relative to rainfall; are respectively the potential recharge groundwater coefficient of piston flow in the soil, represents the precipitation during a period. It should be noted that, is a model parameter, and its range can be determined through experiments or literature research, or a multivariate statistical mathematical relationship between it and influencing factors can be established to reduce the workload of model parameter inversion.

[0027] It should be noted that the groundwater utilization amount is uniform throughout the year and can be obtained from the regional water resources bulletin or estimated based on population and economic data.

[0028] The vadose zone and aquifer with storage and regulation functions can be regarded as a series of linear reservoirs. According to the principle of proportionality and superposition, the rainfall base flow response model determined by the above formulas (1)-(7) is: (8); wherein, represents the lower incomplete Gamma function, respectively represent the Gamma function of, are all model parameters of the rainfall base flow response model.

[0029] S102. Based on the rainfall and base flow data of the study area, the model parameters of the rainfall base flow response model are solved by the genetic algorithm to obtain the target values of the model parameters in the rainfall base flow response model.

[0030] Among them, the study area can be the Loess Plateau, the rainfall data includes the precipitation of each period, and the base flow data includes the outlet base flow and groundwater utilization amount of each period.

[0031] Obtain the outlet base flow of each period in the study area , the groundwater utilization amount of each period , the precipitation of each period, , , , and use the genetic algorithm for the model parameters in formula (8) , , , , , , Optimize to obtain the optimal values of the model parameters, and these optimal values are the target values of the model parameters.

[0032] S103. According to the target values, determine the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow in the study area; the recession unit hydrographs are used to describe the groundwater recharge process in the study area.

[0033] Optionally, according to the target values, determine the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow, including: according to the target values, determine the weight coefficients of the recession unit hydrograph formed by the macropore preferential flow in the study area, the weight coefficients of the recession unit hydrograph formed by the preferential flow, and the weight coefficients of the recession unit hydrograph formed by the soil piston flow; according to the weight coefficients of the recession unit hydrograph formed by the macropore preferential flow in the study area, the weight coefficients of the recession unit hydrograph formed by the preferential flow, and the weight coefficients of the recession unit hydrograph formed by the soil piston flow, determine the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow.

[0034] For the weight coefficients of the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow at any time period, substitute the determined target values of the model parameters into , and the obtained value is the weight coefficient of the recession unit hydrograph formed by the macropore preferential flow in the time period; substitute the determined target values of the model parameters into , and the obtained value is the weight coefficient of the recession unit hydrograph formed by the soil preferential flow in the time period, substitute the determined target values of the model parameters into , and the obtained value is the weight coefficient of the recession unit hydrograph formed by the soil piston flow in the time period.

[0035] According to the weight coefficients of the recession unit hydrograph formed by the macropore preferential flow in the study area, the weight coefficients of the recession unit hydrograph formed by the preferential flow, and the weight coefficients of the recession unit hydrograph formed by the soil piston flow, draw the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow.

[0036] It is also possible to draw the total recession unit hydrograph according to the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow, and the total recession unit hydrograph is the accumulation of the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow at the corresponding time periods.

[0037] As Figure 2 shown, Figure 2 is a schematic diagram of the recession unit hydrographs of the macropore preferential flow, soil preferential flow, and soil piston flow, and the total recession unit hydrograph.

[0038] In one embodiment, based on the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow in the study area, the time lag effect, recharge process, and cumulative recharge flux of base flow on macropore preferential flow, soil preferential flow, and piston flow are determined.

[0039] Specifically, based on the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow, the time lag effect and recharge process of base flow on them can be obtained, and their cumulative recharge fluxes can be statistically calculated. The contributions of the three and the dominant form of regional groundwater recharge can be clarified, and further, the groundwater recharge process and mechanism in the Loess Plateau can be analyzed.

[0040] Specifically, the time lag effect of macropore preferential flow, soil preferential flow, and piston flow is the time when the unit hydrograph approaches 0, that is, g -g1, p - p 1 and w - w 1; the recharge processes of macropore preferential flow, soil preferential flow, and piston flow are respectively: , , .

[0041] The cumulative recharge flux is the sum of the recharge amounts of macropore preferential flow, soil preferential flow, and piston flow in each time period.

[0042] The recharge of groundwater in the Loess Plateau is not only affected by soil preferential flow and piston flow, but also by macropore preferential flow composed of fractures, pores, etc. and the characteristics of the basin. The present invention utilizes the time difference of groundwater recharge by regional macropore preferential flow, soil preferential flow, and piston flow, and combines the recession unit hydrograph method to construct a basin rainfall base flow response model considering land use change, realizing the quantitative characterization of the process of preferential flow and piston flow recharging groundwater in the Loess Plateau. Compared with the existing environmental isotope and hydrochemical tracer methods, this method overcomes the influence of the heterogeneity, scale effect of the hydrological process, and the uncertainty of tracer input on the results, and breaks through the problem that it is difficult to quantitatively characterize the process of preferential flow recharging groundwater at the regional scale. The proposed model method has clear physical meaning, few parameters, and a wide application range, and can be used to evaluate the research on the characteristics of groundwater recharge before and after land use change caused by human activities in the Loess Plateau. This invention has important scientific significance and value for enriching the research methods of groundwater recharge mechanism, and has important application value for ensuring regional water security and the sustainable development and utilization of groundwater resources and serving regional ecological protection.

[0043] When applying the method for analyzing the groundwater recharge process provided by the present invention, it is not necessary to execute according to Figure 1 the order of the steps shown. The specific execution order of each step can be determined as needed, and the present invention does not limit this.

[0044] The above is the method for analyzing the groundwater recharge process provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding device for analyzing the groundwater recharge process, which includes: An acquisition module, configured to acquire a rainfall base flow response model; the rainfall base flow response model is constructed according to the relationship between the river base flow volume, groundwater utilization volume, and base flow volume at the basin outlet formed by macropore preferential flow, soil preferential flow, and soil piston flow; the river base flow volumes formed by macropore preferential flow, soil preferential flow, and soil piston flow are respectively determined based on the differences in the groundwater recharge lag times of macropore preferential flow, soil preferential flow, and soil piston flow and the recession unit hydrograph.

[0045] A solution module, configured to solve the model parameters of the rainfall base flow response model through a genetic algorithm based on the rainfall data and base flow data of the research area, and obtain the target values of the model parameters in the rainfall base flow response model.

[0046] An analysis module, configured to determine the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow in the research area according to the target values; the recession unit hydrograph is used to describe the groundwater recharge process in the research area.

[0047] For the specific limitations of the device for analyzing the groundwater recharge process, reference can be made to the limitations of the method for analyzing the groundwater recharge process in the above text, which will not be elaborated here. Each module in the above device for analyzing the groundwater recharge process can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor of the computer device in hardware form or be independent of it, or can be stored in the memory of the computer device in software form, so as to facilitate the processor to call and execute the operations corresponding to the above modules.

[0048] The present invention also provides a computer-readable storage medium, which stores a computer program, and the computer program can be used to execute the above Figure 1 provided method for analyzing the groundwater recharge process.

[0049] The present invention also provides Figure 3 the structural schematic diagram of the computer device shown in, as Figure 3 shown. At the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for other services. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the above Figure 1 provided method for analyzing the groundwater recharge process.

[0050] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memories. The non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical memory, etc. The volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0051] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope recorded by the present invention.

Claims

1. A method for analyzing the groundwater recharge process, characterized in that, Including: Obtaining a rainfall baseflow response model; the rainfall baseflow response model is constructed based on the relationship between the river baseflow volume, groundwater utilization volume, and baseflow volume at the basin outlet formed by macropore preferential flow, soil preferential flow, and soil piston flow; The river baseflow volumes formed by macropore preferential flow, soil preferential flow, and soil piston flow are respectively determined based on the differences in the lag time of groundwater recharge by macropore preferential flow, soil preferential flow, and soil piston flow and the recession unit hydrograph; Based on the rainfall data and baseflow data of the study area, the model parameters of the rainfall baseflow response model are solved by a genetic algorithm to obtain the target values of the model parameters in the rainfall baseflow response model; According to the target values, determine the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow in the study area; The recession unit hydrograph is used to describe the groundwater recharge process in the study area.

2. The method according to claim 1, wherein The rainfall baseflow response model is: ； Among them, is the base flow at the basin outlet, respectively represent the start time and end time of the macropore preferential flow, represents the precipitation during the represents the proportion of rainfall converted into macropore preferential flow during the represents the weight coefficient of the recession unit hydrograph formed by macropore preferential flow during the respectively represent the start time and end time of the soil preferential flow, represents the potential recharge flux of soil preferential flow during the is the weight coefficient of the recession unit hydrograph formed by soil preferential flow during the respectively represent the start time and end time of the soil piston flow, is the potential groundwater recharge flux of soil piston flow during the is the weight coefficient of the recession unit hydrograph formed by soil piston flow during the is the groundwater utilization amount, represents the lower incomplete Gamma function, respectively represent the Gamma function of All are model parameters of the rainfall base flow response model.

3. The method according to claim 2, wherein ； Among them, is the surface runoff of the time period, is the runoff threshold, indicating the maximum ratio; ； Among them, the subscript represents the agricultural and forestry grassland,[ represents the potential recharge coefficient of groundwater by soil preferential flow,[ represents the land use coefficient corresponding to the agricultural and forestry grassland;[ represents the precipitation during the time period.[ ； Among them, is the potential recharge coefficient of soil piston flow to groundwater, represents the precipitation during the time period.

4. The method according to claim 2, characterized in that, Determining the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow according to the target values includes: According to the target values, determine the weight coefficients of the recession unit hydrograph formed by macropore preferential flow in the study area, the weight coefficient of the recession unit hydrograph formed by preferential flow, and the weight coefficient of the recession unit hydrograph formed by soil piston flow; According to the weight coefficients of the recession unit hydrograph formed by macropore preferential flow in the study area, the weight coefficient of the recession unit hydrograph formed by preferential flow, and the weight coefficient of the recession unit hydrograph formed by soil piston flow, determine the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow.

5. The method according to claim 1, wherein The method further includes: According to the recession unit hydrographs of macropore preferential flow, soil preferential flow, and soil piston flow in the study area, determine the time lag effect, recharge process, and cumulative recharge flux of baseflow on macropore preferential flow, soil preferential flow, and piston flow.

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