A method and system for evaluating carbon dioxide exchange at river water-air interface

Abstract

The present invention discloses a method and system for evaluating the carbon dioxide exchange amount at the water-air interface of a river. The target river space is discretized into a finite number of river sections, and the river section section is generalized to obtain the river section section shape parameters; the water flow characteristics of the section of each river section are calculated by the Saint-Venant equations; the gas transmission rate of each river section is calculated according to a preset gas transmission rate calculation model; the exchange flux of carbon dioxide at the water-air interface of each river section is calculated based on the gas transmission rate of each river section and the block formula; the water surface area of ​​each river section is calculated based on the preset water flow characteristics of each river section and the river section section shape parameters; the product of the water surface area of ​​each river section and the carbon dioxide exchange flux at the water-air interface of the river section is the carbon dioxide exchange amount at the water-air interface of the river section, and the sum of the carbon dioxide exchange amounts at the water-air interface of each river section is the carbon dioxide exchange amount at the water-air interface of the target river. The present invention performs segmented calculations through rivers, and can quickly and accurately evaluate the carbon dioxide exchange amount at the water-air interface of the target river.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon cycle, and in particular to a method and system for evaluating the carbon dioxide exchange amount at a river water-air interface. Background Art

[0002] Rivers connect the land and the ocean. While transporting carbon to the ocean, they also exchange a large amount of carbon dioxide with the atmosphere. Research on carbon exchange at the water-air interface of rivers is of great significance to regional and global carbon cycles. At present, the research on carbon dioxide flux exchange at the water-air interface mainly focuses on waters such as lakes and estuaries. The research on river carbon cycle also focuses on the lateral migration process of river carbon. The research on the carbon dioxide exchange at the water-air interface of rivers is relatively small. At present, the main measurement method is to directly measure the carbon dioxide flux of river water-air in the field by infrared measuring instruments combined with flux boxes. This method requires a lot of manpower, material and financial resources, and has a narrow scope of application. The gas transmission rate at the water-air interface is an important factor affecting the calculation of carbon dioxide exchange at the water-air interface of rivers. At present, the estimation method of the gas transmission rate of carbon dioxide at the water-air interface is mainly obtained through volatile gas tracing, or flux box method and eddy correlation method. Among them, the measurement method of artificially adding tracers is not very applicable under field conditions. The scope of application of flux box method and eddy correlation method is also relatively limited, and it is only applicable to water bodies with slow flow rate. Summary of the invention

[0003] Therefore, the embodiments of the present invention provide a method and system for evaluating the carbon dioxide exchange amount at the water-air interface of a river, which can solve the problems existing in the prior art.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] In a first aspect, an embodiment of the present invention provides a method for evaluating the carbon dioxide exchange amount at a river water-air interface, comprising:

[0006] The target river is spatially discretized into a finite number of river sections, and the river section cross-section is generalized to obtain the river section cross-section shape parameters;

[0007] The flow characteristics of the cross-section of each river section are calculated using the Saint-Venant equations;

[0008] Calculate the gas transmission rate of each river section according to the preset gas transmission rate calculation model;

[0009] Based on the gas transmission rate and bulk formula of each river section, the exchange flux of carbon dioxide at the water-air interface of each river section unit was calculated;

[0010] Calculate the water surface area of ​​each river section based on the preset water flow characteristics and cross-sectional shape parameters of each river section;

[0011] The product of the water surface area of ​​each river section and the carbon dioxide exchange flux at the water-air interface of the river section is the carbon dioxide exchange capacity of the water-air interface of each river section, and the sum of the carbon dioxide exchange capacity of the water-air interface of each river section is the carbon dioxide exchange capacity of the water-air interface of the target river.

[0012] Furthermore, the Saint-Venant equations in the form of partial differential equations are used to describe the water flow characteristics of each river section. The water flow characteristics of each river section are obtained by solving the equations:

[0013]

[0014] Where: A represents the cross-sectional area of ​​the river; Q represents the flow rate of the cross-sectional area; x represents the coordinate along the river channel, with the positive value being in the direction of the water flow; u represents the average flow velocity of the cross-sectional area; g represents the acceleration of gravity; z represents the riverbed elevation of the river section; S0 represents the riverbed slope; S f For friction resistance down the slope.

[0015] Furthermore, the gas transmission rate of each river section is obtained by the following calculation model:

[0016] k=f(u,s,h,W)

[0017] Where: k represents the gas transmission rate; u represents the river flow velocity; s represents the river bottom slope; h represents the river water depth; W represents the river surface width, and f(·) is the correlation function between the gas transmission rate at the water-air interface of the river section and the flow velocity, river bottom slope, water depth and water surface width obtained by the multivariate linear regression method.

[0018] Furthermore, the river flow rate is calculated by the following formula:

[0019]

[0020] Where: u in represents the flow velocity of the inflow section of the river section, which is calculated by the Saint-Venant equations; u out represents the flow velocity of the outflow section of the river section, which is calculated by the Saint-Venant equations;

[0021] The riverbed slope is calculated using the following formula:

[0022]

[0023] Where: z in represents the river water level at the inflow section of the river section, calculated by the Saint-Venant equations; z out represents the river water level at the outflow section of the river section, which is calculated by the Saint-Venant equations; L represents the horizontal distance between the inflow section of the river section and the outflow section of the river section;

[0024] The river depth is calculated using the following formula:

[0025]

[0026] Where: z d,in Indicates the riverbed elevation of the inflow section of a specified river section, z d,out Indicates the riverbed elevation of the outflow section of a specified river section;

[0027] The river surface width is calculated using the following formula:

[0028]

[0029] Where: d in Indicates the bottom width of the trapezoidal section of the river channel at the inflow section; d out Indicates the bottom width of the trapezoidal section of the river channel at the outflow section of the river section; θ in Represents the angle between the slope and the bottom of the trapezoidal section of the inflow section of the river section; θ out It represents the angle between the side slope and the bottom edge of the trapezoidal section at the inflow section of the river section.

[0030] Furthermore, the carbon dioxide flux at the water-air interface of the river section is calculated using the following block formula:

[0031]

[0032] Where k is the gas transmission rate; s is the solubility, which is a function of temperature and salinity; represents the partial pressure of carbon dioxide, which determines the direction of carbon dioxide exchange at the water-air interface. When , it means that the river releases carbon dioxide into the atmosphere; when , indicating that the river absorbs carbon dioxide from the atmosphere.

[0033] Furthermore, the step of calculating the water surface area of ​​each river section based on the preset water flow characteristics of each river section and the cross-sectional shape parameters of the river section includes:

[0034] The water surface area of ​​the river section is calculated by integrating the water surface width of the river section between the inflow section and the outflow section along the river channel, using the following formula:

[0035]

[0036] Where: x represents the coordinate along the river channel, and the positive value is in the direction of the water flow; x in Indicates the coordinate of the inflow section of the river section along the river channel direction; x out Indicates the coordinates of the outflow section of the river along the river channel; W in Indicates the width of the water surface at the inflow section of the river section; W out Indicates the width of the water surface at the outflow section of the river section.

[0037] Furthermore, the carbon dioxide exchange amount at the water-air interface of the target river was calculated by the following formula:

[0038]

[0039] Where: N represents the number of river section units divided into target rivers; i represents the number of river section units; A r,i represents the water surface area of ​​the river section unit numbered i; F co2,i Represents the carbon dioxide exchange flux at the water-air interface of the river section unit numbered i.

[0040] In a second aspect, an embodiment of the present invention provides a system for evaluating carbon dioxide exchange at a river water-air interface, comprising:

[0041] The river section division module is used to spatially discretize the target river into a finite number of river sections and generalize the river section cross-section to obtain the river section cross-section shape parameters;

[0042] The water flow characteristic calculation module of the river section is used to calculate the water flow characteristics of each river section through the Saint-Venant equations;

[0043] A river section gas transmission rate calculation module, used to calculate the gas transmission rate of each river section according to a preset gas transmission rate calculation model;

[0044] The river section gas exchange flux calculation module is used to calculate the carbon dioxide exchange flux of the water-air interface of each river section unit based on the gas transmission rate and bulk formula of each river section;

[0045] A river section water surface area calculation module is used to calculate the water surface area of ​​each river section based on the preset water flow characteristics of each river section and the cross-sectional shape parameters of the river section;

[0046] The carbon dioxide exchange capacity assessment module is used to calculate the product of the water surface area of ​​each river section and the carbon dioxide exchange flux at the water-air interface of the river section as the carbon dioxide exchange capacity of the water-air interface of each river section, and the sum of the carbon dioxide exchange capacity of the water-air interface of each river section is the carbon dioxide exchange capacity of the water-air interface of the target river.

[0047] In a third aspect, an embodiment of the present invention provides a computer device, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor executes the method for evaluating the carbon dioxide exchange amount at the river water-air interface as described in any embodiment of the first aspect of the present invention.

[0048] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the method for evaluating the carbon dioxide exchange amount at the river water-air interface as described in any embodiment of the first aspect of the present invention.

[0049] The technical solution of the present invention has the following advantages:

[0050] The present invention provides a method and system for evaluating the carbon dioxide exchange amount at the water-air interface of a river. The target river space is discretized into a finite number of river sections, and the river section section is generalized to obtain the river section section shape parameters; the water flow characteristics of the section of each river section are calculated by the Saint-Venant equations; the gas transmission rate of each river section is calculated according to the preset gas transmission rate calculation model; the exchange flux of carbon dioxide at the water-air interface of each river section is calculated based on the gas transmission rate of each river section and the block formula; the water surface area of ​​each river section is calculated based on the preset water flow characteristics of each river section and the river section section shape parameters; the product of the water surface area of ​​each river section and the carbon dioxide exchange flux at the water-air interface of the river section is the carbon dioxide exchange amount at the water-air interface of the river section, and the sum of the carbon dioxide exchange amounts at the water-air interface of each river section is the carbon dioxide exchange amount at the water-air interface of the target river. The present invention can quickly and accurately evaluate the carbon dioxide exchange amount at the water-air interface of the target river by performing segmented calculations on the river. Compared with the traditional method, it has the characteristics of low investment, high calculation accuracy, strong physical mechanism, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 A flowchart of a specific example of a method for evaluating the amount of carbon dioxide exchange at a river water-air interface provided in an embodiment of the present invention;

[0053] Figure 2 Figure Schematic diagram of the spatial discretization of target rivers in an embodiment of the present invention;

[0054] Figure 3 FIG. 1 is a schematic diagram of a cross section of a trapezoidal river section of a target river in an embodiment of the present invention;

[0055] Figure 4 FIG. 1 is a module composition diagram of an example of a system for evaluating the carbon dioxide exchange amount at the water-air interface of a river provided in an embodiment of the present invention;

[0056] Figure 5A composition diagram of a specific example of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0059] Example 1

[0060] The present invention provides a method for evaluating the carbon dioxide exchange amount at the water-air interface of a river. Figure 1 As shown, the method comprises the following steps:

[0061] Step S1: spatially discretize the target river into a finite number of river sections, and generalize the river section cross-section to obtain the river section cross-section shape parameters.

[0062] The target river is discretized into a finite number of river sections, and the river sections are connected at the end, such as Figure 2 As shown in , the target river is discretized into 10 river sections, and the river section section is generalized to be approximately a trapezoidal section, as shown in Figure 3 As shown, the shape parameters include: river water surface width W, angle θ between the slope and bottom of the trapezoidal section of the river section, river water depth h, and bottom width d of the trapezoidal section.

[0063] Step S2: Calculate the water flow characteristics of the cross section of each river section through the Saint-Venant equations.

[0064] In the embodiment of the present invention, the Saint-Venant equations in the form of partial differential equations are used to describe the water flow characteristics of each river section, and the water flow characteristics of each river section are obtained by solving the equations:

[0065]

[0066] Where: A represents the cross-sectional area of ​​the river; Q represents the flow rate of the cross-sectional area; x represents the coordinate along the river channel, with the positive value being in the direction of the water flow; u represents the average flow velocity of the cross-sectional area; g represents the acceleration of gravity; z represents the riverbed elevation of the river section; S0 represents the riverbed slope; S f is the friction slope, which can be calculated using Manning's formula.

[0067] Step S3: Calculate the gas transmission rate of each river section according to the preset gas transmission rate calculation model.

[0068] In general, the gas transmission rate at the water-gas interface of a river is significantly correlated with the flow velocity, river bottom slope, water depth and water surface width. The embodiment of the present invention adopts a multivariate linear regression method to establish the correlation between the flow velocity, river bottom slope, water depth and water surface width and the gas interaction rate, and obtains a calculation model for the k value of a specified river. The gas transmission rate of each river section is obtained by the following calculation model:

[0069] k=f(u,s,h,W)

[0070] Where: k represents the gas transmission rate; u represents the river flow velocity; s represents the river bottom slope; h represents the river water depth; W represents the river surface width, and f(·) is the correlation function of the gas transmission rate at the water-air interface of the river section obtained by the multivariate linear regression method with the flow velocity, river bottom slope, water depth and water surface width. Different rivers have different correlation functions.

[0071] The river flow velocity is the average of the inflow section flow velocity and the outflow section flow velocity of the river section, and is calculated using the following formula:

[0072]

[0073] Where: u in represents the flow velocity of the inflow section of the river section, which is calculated by the Saint-Venant equations; u out represents the flow velocity of the outflow section of the river section, which is calculated by the Saint-Venant equations;

[0074] The riverbed slope is calculated using the following formula:

[0075]

[0076] Where: z in represents the river water level at the inflow section of the river section, calculated by the Saint-Venant equations; z out represents the river water level at the outflow section of the river section, which is calculated by the Saint-Venant equations; L represents the horizontal distance between the inflow section of the river section and the outflow section of the river section;

[0077] The river depth is the average of the inflow section depth and the outflow section depth (the section depth is the difference between the section water level and the section river bottom elevation), calculated by the following formula:

[0078]

[0079] Where: z d,in Indicates the riverbed elevation of the inflow section of a specified river section, z d,out Indicates the riverbed elevation of the outflow section of a specified river section;

[0080] The river water surface width is the average of the water surface width of the river section inflow section and the water surface width of the river section outflow section, and is calculated by the following formula:

[0081]

[0082] Where: d in Indicates the bottom width of the trapezoidal section of the river channel at the inflow section; d out Indicates the bottom width of the trapezoidal section of the river channel at the outflow section of the river section; θ in Represents the angle between the slope and the bottom of the trapezoidal section of the inflow section of the river section; θ out It represents the angle between the side slope and the bottom edge of the trapezoidal section at the inflow section of the river section.

[0083] Step S4: Based on the gas transmission rate of each river section and the bulk formula, the exchange flux of carbon dioxide at the water-air interface of each river section unit is calculated.

[0084] The carbon dioxide flux at the water-air interface of the river section in the embodiment of the present invention is calculated using the following block formula:

[0085]

[0086] Where k is the gas transmission rate; s is the solubility, which is a function of temperature and salinity and can be measured in a laboratory environment; represents the partial pressure of carbon dioxide, which determines the direction of carbon dioxide exchange at the water-air interface. When , it means that the river releases carbon dioxide into the atmosphere; when When , it means that the river absorbs carbon dioxide from the atmosphere, and its value can be measured in an experimental environment.

[0087] Step S5: Calculate the water surface area of ​​each river section based on the preset water flow characteristics and cross-sectional shape parameters of each river section.

[0088] The water surface area of ​​the river section in the embodiment of the present invention is calculated by integrating the water surface width of the river section between the inflow section and the outflow section of the river section along the river channel direction, and is calculated by the following formula:

[0089]

[0090] Where: x represents the coordinate along the river channel, and the positive value is in the direction of the water flow; x in Indicates the coordinate of the inflow section of the river section along the river channel direction; x out Indicates the coordinates of the outflow section of the river along the river channel; W in Indicates the width of the water surface at the inflow section of the river section; W out Indicates the width of the water surface at the outflow section of the river section.

[0091] Step S6: The product of the water surface area of ​​each river section and the carbon dioxide exchange flux at the water-air interface of the river section is the carbon dioxide exchange capacity of the water-air interface of each river section, and the sum of the carbon dioxide exchange capacity of the water-air interface of each river section is the carbon dioxide exchange capacity of the water-air interface of the target river.

[0092] The amount of carbon dioxide exchange at the water-air interface of the target river is calculated using the following formula:

[0093]

[0094] Where: N represents the number of river section units divided into target rivers; i represents the number of river section units; A r,i represents the water surface area of ​​the river section unit numbered i; F co2,i Represents the carbon dioxide exchange flux at the water-air interface of the river section unit numbered i.

[0095] The method for evaluating the carbon dioxide exchange amount at the water-air interface of a river provided in an embodiment of the present invention can quickly and accurately evaluate the carbon dioxide exchange amount at the water-air interface of a target river by performing segmented calculations on the river. Compared with traditional methods, this method has the characteristics of low investment, high calculation accuracy, and strong physical mechanism.

[0096] Example 2

[0097] The embodiment of the present invention provides a system for evaluating the carbon dioxide exchange amount at the water-air interface of a river. Figure 4 As shown, including:

[0098] The river section division module 1 is used to spatially discretize the target river into a finite number of river sections, and generalize the river section section to obtain the river section section shape parameters; this module executes the method described in step S1 of embodiment 1, which will not be repeated here.

[0099] The water flow characteristic calculation module 2 of the river section is used to calculate the water flow characteristics of each river section through the Saint-Venant equations; the module executes the method described in step S2 of embodiment 1, which will not be repeated here.

[0100] The gas transmission rate calculation module 3 is used to calculate the gas transmission rate of each river section according to the preset gas transmission rate calculation model. This module executes the method described in step S3 of embodiment 1, which will not be repeated here.

[0101] The river section gas exchange flux calculation module 4 is used to calculate the exchange flux of carbon dioxide at the water-air interface of each river section unit based on the gas transmission rate of each river section and the bulk formula. This module executes the method described in step S4 of embodiment 1, which will not be repeated here.

[0102] The river section water surface area calculation module 5 is used to calculate the water surface area of ​​each river section based on the preset water flow characteristics and cross-sectional shape parameters of each river section; this module executes the method described in step S5 of embodiment 1, which will not be repeated here.

[0103] The carbon dioxide exchange capacity evaluation module 6 is used to calculate the product of the water surface area of ​​each river section and the carbon dioxide exchange flux of the water-air interface of the river section as the carbon dioxide exchange capacity of the water-air interface of each river section, and the sum of the carbon dioxide exchange capacity of the water-air interface of each river section as the carbon dioxide exchange capacity of the water-air interface of the target river. This module executes the method described in step S6 of embodiment 1, which will not be repeated here.

[0104] Example 3

[0105] An embodiment of the present invention provides a computer device, such as Figure 5 As shown, it includes: at least one processor 501, such as a CPU (Central Processing Unit), at least one communication interface 503, a memory 504, and at least one communication bus 502. Among them, the communication bus 502 is used to realize the connection and communication between these components. Among them, the communication interface 503 may include a display screen (Display), a keyboard (Keyboard), and the optional communication interface 503 may also include a standard wired interface and a wireless interface. The memory 504 may be a high-speed RAM memory (Ramdom Access Memory, volatile random access memory), or a non-volatile memory (non-volatile memory), such as at least one disk memory. The memory 504 may also be at least one storage device located away from the aforementioned processor 501. Among them, the processor 501 can execute the river water-air interface carbon dioxide exchange amount evaluation method of Example 1. A set of program codes are stored in the memory 504, and the processor 501 calls the program code stored in the memory 504 to execute the river water-air interface carbon dioxide exchange amount evaluation method of Example 1.

[0106] The communication bus 502 may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus. The communication bus 502 may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 Although only one line is used in the diagram, it does not mean that there is only one bus or only one type of bus.

[0107] Among them, the memory 504 may include a volatile memory (English: volatile memory), such as a random access memory (English: random-access memory, abbreviated: RAM); the memory may also include a non-volatile memory (English: non-volatile memory), such as a flash memory (English: flash memory), a hard disk drive (English: hard disk drive, abbreviated: HDD) or a solid-state drive (English: solid-state drive, abbreviated: SSD); the memory 504 may also include a combination of the above types of memory.

[0108] The processor 501 may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and a NP.

[0109] The processor 501 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0110] Optionally, the memory 504 is also used to store program instructions. The processor 501 can call the program instructions to implement the method for evaluating the carbon dioxide exchange amount at the river water-air interface in Example 1 of the present application.

[0111] The embodiment of the present invention also provides a computer-readable storage medium, on which computer-executable instructions are stored, and the computer-executable instructions can execute the method for evaluating the carbon dioxide exchange amount at the river water-air interface of embodiment 1. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk (HDD) or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above-mentioned types of memory.

[0112] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for evaluating the carbon dioxide exchange amount at the water-air interface of a river, characterized in that: include: The target river is spatially discretized into a finite number of river sections, and the river section cross-section is generalized to obtain the river section cross-section shape parameters; The Saint-Venant equations in the form of partial differential equations are used to describe the water flow characteristics of each river section. The water flow characteristics of each river section are obtained by solving the equations: Where: A represents the cross-sectional area of ​​the river; Q represents the flow rate of the cross-sectional area; x represents the coordinate along the river channel, with the positive value being in the direction of the water flow; u represents the average flow velocity of the cross-sectional area; g represents the acceleration of gravity; z represents the riverbed elevation of the river section; S0 represents the riverbed slope; S f For friction resistance, slope descent; According to the preset gas transmission rate calculation model, the gas transmission rate of each river section is calculated. The gas transmission rate of each river section is obtained by the following calculation model: k=f(u,s,h,W) Where: k represents the gas transmission rate; u represents the river flow velocity; s represents the river bottom slope; h represents the river water depth; W represents the river surface width, and f(·) is the correlation function between the gas transmission rate at the water-air interface of the river section and the flow velocity, river bottom slope, water depth and water surface width obtained by the multivariate linear regression method; Where: The river flow rate is calculated by the following formula: Where: u in represents the flow velocity of the inflow section of the river section, which is calculated by the Saint-Venant equations; u out represents the flow velocity of the outflow section of the river section, which is calculated by the Saint-Venant equations; The riverbed slope is calculated using the following formula: Where: z in represents the river water level at the inflow section of the river section, calculated by the Saint-Venant equations; z out represents the river water level at the outflow section of the river section, which is calculated by the Saint-Venant equations; L represents the horizontal distance between the inflow section of the river section and the outflow section of the river section; The river depth is calculated using the following formula: Where: z d,in Indicates the riverbed elevation of the inflow section of a specified river section, z d,out Indicates the riverbed elevation of the outflow section of a specified river section; The river surface width is calculated using the following formula: Where: d in Indicates the bottom width of the trapezoidal section of the river channel at the inflow section; d out Indicates the bottom width of the trapezoidal section of the river channel at the outflow section of the river section; θ in Represents the angle between the slope and the bottom of the trapezoidal section of the inflow section of the river section; θ out It represents the angle between the slope and the bottom of the trapezoidal section of the inflow section of the river section; Based on the gas transmission rate and block formula of each river section, the exchange flux of carbon dioxide at the water-air interface of each river section unit is calculated. The exchange flux of carbon dioxide at the water-air interface of the river section is calculated using the following block formula: Where: k represents the gas transmission rate; s represents the solubility, which is a function of temperature and salinity; represents the partial pressure of carbon dioxide, which determines the direction of carbon dioxide exchange at the water-air interface. When , it means that the river releases carbon dioxide into the atmosphere; when When , it means that the river absorbs carbon dioxide from the atmosphere; Based on the preset flow characteristics and cross-sectional shape parameters of each river section, the water surface area of ​​each river section is calculated, including: The water surface area of ​​the river section is calculated by integrating the water surface width of the river section between the inflow section and the outflow section along the river channel, using the following formula: Where: x represents the coordinate along the river channel, and the positive value is in the direction of the water flow; x in Indicates the coordinate of the inflow section of the river section along the river channel direction; x out Indicates the coordinates of the outflow section of the river along the river channel; W in Indicates the width of the water surface at the inflow section of the river section; W out Indicates the width of the water surface at the outflow section of the river section; The product of the water surface area of ​​each river section and the carbon dioxide exchange flux at the water-air interface of the river section is the carbon dioxide exchange capacity of the water-air interface of each river section. The sum of the carbon dioxide exchange capacity of the water-air interface of each river section is the carbon dioxide exchange capacity of the water-air interface of the target river. The carbon dioxide exchange capacity of the water-air interface of the target river is calculated by the following formula: Where: N represents the number of river section units divided into target rivers; i represents the number of river section units; A r,i represents the water surface area of ​​the river section unit numbered i; F co2,i Represents the carbon dioxide exchange flux at the water-air interface of the river section unit numbered i.

2. A system for evaluating carbon dioxide exchange at a river water-air interface, used to implement the method of claim 1, characterized in that: include: The river section division module is used to spatially discretize the target river into a finite number of river sections and generalize the river section cross-section to obtain the river section cross-section shape parameters; The water flow characteristic calculation module of the river section is used to calculate the water flow characteristics of each river section through the Saint-Venant equations; A river section gas transmission rate calculation module, used to calculate the gas transmission rate of each river section according to a preset gas transmission rate calculation model; The river section gas exchange flux calculation module is used to calculate the carbon dioxide exchange flux of the water-air interface of each river section unit based on the gas transmission rate and bulk formula of each river section; A river section water surface area calculation module is used to calculate the water surface area of ​​each river section based on the preset water flow characteristics of each river section and the cross-sectional shape parameters of the river section; The carbon dioxide exchange capacity assessment module is used to calculate the product of the water surface area of ​​each river section and the carbon dioxide exchange flux at the water-air interface of the river section as the carbon dioxide exchange capacity of the water-air interface of each river section, and the sum of the carbon dioxide exchange capacity of the water-air interface of each river section is the carbon dioxide exchange capacity of the water-air interface of the target river.

3. A computer device, characterized in that: include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor executes the method for evaluating the carbon dioxide exchange amount at the river water-air interface as described in claim 1.

4. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the method for evaluating the carbon dioxide exchange amount at the river water-air interface as described in claim 1.

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