River health state assessment method for diffusion analysis

Abstract

The invention relates to the technical field of river health state assessment, and discloses a river health state assessment method for diffusion analysis, and the method comprises the steps: obtaining the position of a potential pollution source of a target river and the pollutant discharge amount, and carrying out the pollution propagation path analysis of the target river; and collecting an evaluation index value sequence of the target river in the river health evaluation index system, and evaluating the river health state of the sampling position by using the evaluation index value sequence. According to the method, diffusion analysis is carried out on pollutant emission, pollutant concentration propagation values of pollutants at different target river nodes are obtained, river pollution propagation path extraction based on diffusion analysis is realized, river health state evaluation is carried out on different sampling positions, and the evaluation accuracy is improved. And performing interpolation fitting on the river health states of the continuous sampling positions by adopting an interpolation fitting mode to obtain river overall health state assessment distribution describing the river health states of the target river at different positions, and accurately positioning a river region with a relatively low health state.

Description

Technical Field

[0001] The invention relates to the technical field of river health status assessment, and in particular to a river health status assessment method based on diffusion analysis. Background Art

[0002] With the development of social economy and population growth, the global demand for water resources is increasing, and the rational management and protection of water resources has become more important. As a key part of the earth's water cycle, rivers not only provide important functions such as water source, irrigation, transportation, and energy, but also carry rich ecosystems. River health refers to the ability of a river to maintain its physical, chemical, and ecological functions in its natural state or through appropriate human intervention. Assessing the health of a river helps to identify problems in a timely manner, guide management decisions, and formulate reasonable river restoration and protection measures. Traditionally, river health assessment is mainly carried out through water quality monitoring, ecological surveys, and other means. However, these methods can often only partially reflect the health of the river, lack comprehensiveness, systematicness, and sustainability, and it is difficult to accurately reflect the overall health of the river ecosystem. Summary of the invention

[0003] In view of this, the present invention provides a river health status assessment method based on diffusion analysis, which can more comprehensively reflect the ecological function and pollution diffusion status of the river by analyzing the interaction and transmission process between various factors in the river health status, and provide a new perspective and tool for the assessment of river health.

[0004] To achieve the above object, the present invention provides a method for evaluating river health status by diffusion analysis, comprising the following steps: S1: Construct a river health assessment indicator system; S2: Obtain the location of potential pollution sources and pollutant emissions of the target river, build a river pollution propagation path analysis model, and perform pollution propagation path analysis on the target river; S3: Sampling the pollution propagation path according to the preset path interval, obtaining the evaluation index value sequence of the target river in the river health evaluation index system, and using the evaluation index value sequence to evaluate the river health status at the sampling location; S4: Perform interpolation fitting on the river health status of consecutive sampling locations in the pollution propagation path to obtain the overall river health status assessment distribution of the target river.

[0005] As a further improvement method of the present invention: Optionally, constructing a river health evaluation index system in step S1 includes: The river health evaluation index system includes chemical property evaluation indicators and physical property evaluation indicators. The chemical property indicators include pH value index, dissolved oxygen content index, biochemical oxygen demand index, chemical oxygen demand index, nitrogen content index, phosphorus content index, ammonia nitrogen content index and heavy metal concentration index. The physical property evaluation indicators include temperature index, turbidity index, transparency index and conductivity index.

[0006] Optionally, obtaining the location of potential pollution sources and pollutant discharge of the target river in step S2 includes: The potential pollution source of the target river is a source that can directly discharge pollutants into the target river through a fixed discharge location, and the fixed discharge location includes a pipeline and a discharge port; The pollutant emission amount of the potential pollution source of the river is the mass of pollutants discharged into the target river by the potential pollution source of the river, wherein the pollutants are the wastewater discharged by the potential pollution source of the river.

[0007] Optionally, the constructing of a river pollution propagation path analysis model and performing pollution propagation path analysis on a target river includes: The river pollution propagation path analysis model takes the location of the potential pollution source of the river as input, takes the pollutant emission as the intermediate value, and takes the path where the pollutant concentration gradient change is less than the preset threshold as the pollution propagation path of the potential pollution source location of the river; The river pollution propagation path analysis model includes a target river node graph construction module, a pollutant concentration propagation module, a pollutant concentration gradient change module and a pollution propagation path generation module; The target river node graph construction module is used to construct the target river into a node graph, wherein the node graph is composed of nodes and edges. The nodes include the source of the target river, the confluence point of the tributaries, the river branch points and the location of the potential pollution source of the river. The edges describe the river flow relationship between the nodes. If there is a river between the nodes, the flow of the river is represented by an arrow. The pollutant concentration propagation module uses the pollutant discharge of the potential pollution source of the river as the intermediate value and the pollutant concentration propagation value of the downstream node of the potential pollution source position of the river in the node graph as the output; The pollutant concentration gradient change module is used to calculate the pollution gradient change value of the pollutant concentration propagation value of the adjacent nodes. The pollution gradient change value of the pollutant concentration propagation value of the adjacent nodes Node1 and Node2 is : ; in: Represents the pollutant concentration propagation value of node Node1, Indicates the pollutant concentration propagation value of node Node2; The pollution propagation path generation module is used to evaluate the pollution gradient change values ​​between multiple consecutive adjacent nodes. If the pollution gradient change values ​​are all less than a preset threshold, the river path formed by the multiple consecutive adjacent nodes is used as a set of pollution propagation paths for the potential pollution source locations of the river.

[0008] Optionally, the expression of pollutant concentration propagation in the pollutant concentration propagation module is: ; in: represents an exponential function with a natural constant as base, represents the pollutant discharge of the potential pollution source of the river, t represents the preset propagation time, s represents the river flow velocity, Represents the downstream node The distance from the potential pollution source of the river, G represents the diffusion coefficient, Indicates the downstream node The pollutant concentration propagation value after propagation time t.

[0009] Optionally, in step S3, sampling the pollution propagation path according to a preset path interval includes: The sampling weight of the pollution propagation path is calculated based on the path length of the pollution propagation path and the importance of the nodes, and the pollution propagation path is sampled in descending order of the sampling weight; The starting node of the pollution propagation path is used as the initial sampling position, and the preset path interval is used as the distance interval between adjacent sampling positions to sample the target river, obtain river water samples of the target river at different sampling positions, measure the evaluation index values ​​of different indicators of the river water samples in the river health evaluation index system, and form an evaluation index value sequence of the target river at the sampling position. The river water sample at each sampling position is 100 ml.

[0010] Optionally, the evaluating the river health status at the sampling location using the evaluation index value sequence includes: The evaluation index value sequence of the rth sampling position of the pollution propagation path is : ; in: These are the evaluation index values ​​of pH value, dissolved oxygen content, biochemical oxygen demand, chemical oxygen demand, nitrogen content, phosphorus content, ammonia nitrogen content and heavy metal concentration of the river water sample at the rth sampling position; They are the evaluation index values ​​of the temperature index, turbidity index, transparency index and conductivity index of the river water sample at the rth sampling position; , R represents the number of sampling locations along the pollution propagation path; The evaluation index value sequence is standardized by minimum-maximum normalization; A linear function is used to map the standardized evaluation index value sequence into the river health status, and the river health status of all sampling locations in the pollution propagation path is obtained. The river health status of the rth sampling location in the pollution propagation path is : ; in: Represents the evaluation index value sequence The standardized processing result of , w represents the weight coefficient in the linear function, b represents the bias coefficient in the linear function, and T represents transposition; The weight coefficient and bias coefficient in the linear function are solved by using the loss function training method. The expression of the loss function is: : ; in: Represents the parameters to be solved, including weight coefficients and bias coefficients, represents the L2 norm; represents the real river health status of the hth group of training samples, Indicates the parameters to be solved The estimated river health status of the hth group of training samples is, , H represents the total number of training samples, represents the control coefficient.

[0011] Optionally, in step S4, interpolation fitting is performed on the river health status of continuous sampling positions in the pollution propagation path, including: The interpolation fitting process is: Obtain the river health status of continuous sampling locations in the pollution propagation path to form a discrete sequence of river health status; Initializing an interpolation fitting function of a pollution propagation path, wherein the interpolation fitting function takes the distance between the river position and the position of a potential pollution source in the river as an independent variable and takes the river health status at the river position as an output; Calculate the error value of the initialized interpolation fitting function, and iterate the coefficients of the interpolation fitting function until the error value of the interpolation fitting function obtained by iteration is lower than a preset error threshold; The interpolation fitting function obtained by iteration is used to generate the river health status of different river locations, and the lowest river health status of each river location is retained to obtain the overall river health status assessment distribution of the target river.

[0012] In order to solve the above problem, the present invention provides an electronic device, the electronic device comprising: A memory storing at least one instruction; Communication interface, enabling electronic equipment to communicate; and The processor executes the instructions stored in the memory to implement the river health status assessment method based on diffusion analysis as described above.

[0013] In order to solve the above problems, the present invention also provides a computer-readable storage medium, in which at least one instruction is stored. The at least one instruction is executed by a processor in an electronic device to implement the river health status assessment method based on diffusion analysis as described above.

[0014] Compared with the prior art, the present invention proposes a river health status assessment method based on diffusion analysis, which has the following advantages: First, this scheme proposes a diffusion analysis method for river pollution. Based on the location of the potential pollution source of the target river, the pollutant emission is diffused and analyzed to obtain the pollutant concentration propagation value of the pollutants at different target river nodes, and the pollution gradient change value of the adjacent target river nodes is calculated. The river path composed of multiple target river nodes whose pollution gradient change is less than the preset threshold is used as a group of pollution propagation paths of the potential pollution source location of the river, so as to realize the extraction of river pollution propagation paths based on diffusion analysis, and obtain the sampling weight based on the importance calculation of the pollution transmission path. The pollution propagation paths are sampled in the order of sampling weight from high to low, and the river water samples of each group of pollution propagation paths at different sampling locations are obtained.

[0015] At the same time, this scheme proposes a method for evaluating the overall health status of rivers. River water samples are measured based on the river health evaluation index system to obtain evaluation index values ​​that characterize the health of the target river, and the evaluation index values ​​are converted into the river health status of the sampling location. The interpolation fitting method is used to interpolate and fit the river health status of continuous sampling locations. The radial basis function is introduced in the interpolation process to improve the smoothness of the interpolation result. There is no high-order polynomial in the interpolation fitting function, and the oscillation problem of high-order polynomial interpolation will not occur. The result is more stable. The interpolation fitting function is composed of polynomials and radial basis functions. The polynomial part can provide a supplement to the global trend, and the radial basis function part can dynamically adjust the local characteristics according to the distance between points, thereby improving the accuracy of the interpolation fitting results, and obtaining the overall river health status assessment distribution that describes the river health status of the target river at different locations, and accurately locating the river area with a lower health status. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic flow chart of a river health status assessment method based on diffusion analysis provided in one embodiment of the present invention.

[0017] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0018] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0019] The embodiment of the present application provides a method for evaluating the health status of a river by diffusion analysis. The execution subject of the method for evaluating the health status of a river by diffusion analysis includes but is not limited to at least one of the electronic devices such as a server and a terminal that can be configured to execute the method provided by the embodiment of the present application. In other words, the method for evaluating the health status of a river by diffusion analysis can be executed by software or hardware installed on a terminal device or a server device, and the software can be a blockchain platform. The server includes but is not limited to: a single server, a server cluster, a cloud server or a cloud server cluster, etc.

[0020] Reference Figure 1 , Embodiment 1 of the present invention is: A river health status assessment method based on diffusion analysis includes the following steps: S1: Construct a river health assessment indicator system.

[0021] The river health evaluation index system is constructed in step S1, including: The river health evaluation index system includes chemical property evaluation indexes and physical property evaluation indexes. The chemical property indexes include pH value index, dissolved oxygen content index, biochemical oxygen demand index, chemical oxygen demand index, nitrogen content index, phosphorus content index, ammonia nitrogen content index and heavy metal concentration index. The physical property evaluation indexes include temperature index, turbidity index, transparency index and conductivity index. Specifically, a thermometer, turbidity meter, Secchi disk and conductivity meter can be used to measure the evaluation index values ​​of physical properties of river water samples; pH test paper can be used to measure the evaluation index values ​​of pH value of river water samples; a dissolved oxygen meter can be used to measure the evaluation index values ​​of dissolved oxygen content of river water samples; potassium dichromate method can be used to measure the evaluation index values ​​of chemical oxygen demand of river water samples; the reduction in dissolved oxygen in river water samples after 5 days of cultivation can be measured as the evaluation index value of biochemical oxygen demand.

[0022] S2: Obtain the location of potential pollution sources and pollutant emissions of the target river, build a river pollution propagation path analysis model, and conduct pollution propagation path analysis on the target river.

[0023] The step S2 obtains the location of the potential pollution source and the amount of pollutant discharged of the target river, including: The potential pollution source of the target river is a source that can directly discharge pollutants into the target river through a fixed discharge location, and the fixed discharge location includes a pipeline and a discharge port; As an embodiment of the present invention, the sources include chemical plants, paper mills, pharmaceutical factories, textile factories, residential areas, livestock and poultry farms, aquaculture farms, and power plants located near the target river; The pollutant emission amount of the potential pollution source of the river is the mass of pollutants discharged into the target river by the potential pollution source of the river, wherein the pollutants are the wastewater discharged by the potential pollution source of the river.

[0024] The construction of the river pollution propagation path analysis model and the analysis of the pollution propagation path of the target river include: The river pollution propagation path analysis model takes the location of the potential pollution source of the river as input, takes the pollutant emission as the intermediate value, and takes the path where the pollutant concentration gradient change is less than the preset threshold as the pollution propagation path of the potential pollution source location of the river; The river pollution propagation path analysis model includes a target river node graph construction module, a pollutant concentration propagation module, a pollutant concentration gradient change module and a pollution propagation path generation module; The target river node graph construction module is used to construct the target river into a node graph, wherein the node graph is composed of nodes and edges. The nodes include the source of the target river, the confluence point of the tributaries, the river branch points and the location of the potential pollution source of the river. The edges describe the river flow relationship between the nodes. If there is a river between the nodes, the flow of the river is represented by an arrow. The pollutant concentration propagation module uses the pollutant discharge of the potential pollution source of the river as the intermediate value and the pollutant concentration propagation value of the downstream node of the potential pollution source position of the river in the node graph as the output; The pollutant concentration gradient change module is used to calculate the pollution gradient change value of the pollutant concentration propagation value of the adjacent nodes. The pollution gradient change value of the pollutant concentration propagation value of the adjacent nodes Node1 and Node2 is : ; in: Represents the pollutant concentration propagation value of node Node1, Indicates the pollutant concentration propagation value of node Node2; The pollution propagation path generation module is used to evaluate the pollution gradient change values ​​between a plurality of consecutive adjacent nodes. If the pollution gradient change values ​​are all less than a preset threshold, the river path formed by the plurality of consecutive adjacent nodes is used as a set of pollution propagation paths for the potential pollution source location of the river. As an embodiment of the present invention, if a pollution propagation path completely contains another shorter pollution propagation path, the shorter path is regarded as a part of the longer path, and only the longer path is retained as a representative to avoid duplicate records.

[0025] The expression of pollutant concentration propagation in the pollutant concentration propagation module is: ; in: represents an exponential function with a natural constant as base, represents the pollutant discharge of the potential pollution source of the river, t represents the preset propagation time, s represents the river flow velocity, Indicates the downstream node The distance from the potential pollution source of the river, G represents the diffusion coefficient, Indicates the downstream node The pollutant concentration propagation value after propagation time t.

[0026] S3: Sample the pollution propagation path according to the preset path interval to obtain the evaluation index value sequence of the target river in the river health evaluation index system, and use the evaluation index value sequence to evaluate the river health status at the sampling location.

[0027] In the step S3, sampling the pollution propagation path according to the preset path interval includes: The sampling weight of the pollution propagation path is calculated based on the path length of the pollution propagation path and the importance of the nodes, and the pollution propagation path is sampled in descending order of the sampling weight; The starting node of the pollution propagation path is used as the initial sampling position, and the preset path interval is used as the distance interval between adjacent sampling positions to sample the target river, obtain river water samples of the target river at different sampling positions, measure the evaluation index values ​​of different indicators of the river water samples in the river health evaluation index system, and form an evaluation index value sequence of the target river at the sampling position. The river water sample at each sampling position is 100 ml.

[0028] As a preferred embodiment of the present invention, based on the number of pollution propagation paths associated with nodes in the pollution propagation path, the larger the number, the more likely the node is a super pollution propagator of a potential pollution source in the river, thereby measuring the importance of the pollution propagation path in the pollution propagation process, and using the proportion of river paths passing through the pollution propagation path as the proportion of river flow tasks undertaken by the pollution propagation path in the target river node graph. The higher the proportion, the more target river nodes connected by the pollution propagation path. The sampling weight calculation formula of the pollution propagation path Load is: ; in: Represents the sampling weight of the pollution propagation path Load; represents the number of pollution propagation paths that include the mth node in the pollution propagation path Load, represents the number of nodes in the target river node graph, , M represents the number of nodes that pollute the propagation path Load; represents the node set in the target river node graph, Indicates passing through node The number of river paths, Indicates passing through node The number of river paths that contain the pollution propagation path Load.

[0029] The method of evaluating the river health status at the sampling location using the evaluation index value sequence includes: The evaluation index value sequence of the rth sampling position of the pollution propagation path is : ; in: These are the evaluation index values ​​of pH value, dissolved oxygen content, biochemical oxygen demand, chemical oxygen demand, nitrogen content, phosphorus content, ammonia nitrogen content and heavy metal concentration of the river water sample at the rth sampling position; They are the evaluation index values ​​of the temperature index, turbidity index, transparency index and conductivity index of the river water sample at the rth sampling position; , R represents the number of sampling locations along the pollution propagation path; The evaluation index value sequence is standardized by minimum-maximum normalization; A linear function is used to map the standardized evaluation index value sequence into the river health status, and the river health status of all sampling locations in the pollution propagation path is obtained. The river health status of the rth sampling location in the pollution propagation path is : ; in: Represents the evaluation index value sequence The standardized processing result of , w represents the weight coefficient in the linear function, b represents the bias coefficient in the linear function, and T represents transposition; The weight coefficient and bias coefficient in the linear function are solved by using the loss function training method. The expression of the loss function is: : ; in: Represents the parameters to be solved, including weight coefficients and bias coefficients, represents the L2 norm; represents the real river health status of the hth group of training samples, Indicates the parameters to be solved The estimated river health status of the hth group of training samples is, , H represents the total number of training samples, Represents the control coefficient. As a preferred embodiment of the present invention, Specifically, the loss function can be solved by using one or more combination algorithms of gradient descent algorithm, Lagrangian method and Newton iteration method.

[0030] S4: Perform interpolation fitting on the river health status of consecutive sampling locations in the pollution propagation path to obtain the overall river health status assessment distribution of the target river.

[0031] In the step S4, interpolation fitting is performed on the river health status of continuous sampling locations in the pollution propagation path, including: The interpolation fitting process is: Obtain the river health status of continuous sampling locations in the pollution propagation path to form a discrete sequence of river health status: ; in: represents the distance between the nth sampling location in the pollution propagation path and the potential pollution source location of the river, represents the river health status at the nth sampling location in the pollution propagation path, ,N represents the total number of sampling locations in the pollution propagation path; Initialize the interpolation fitting function of the pollution propagation path, the interpolation fitting function takes the distance between the river position and the potential pollution source position of the river as the independent variable, and takes the river health status of the river position as the output. The initialized interpolation fitting function is: ; in: represents the initialized interpolation fitting function, represents the independent variable, Indicates the distance from the potential pollution source of the river The river health status of the river at the river location, Represents the coefficients of the initialized interpolation fitting function; The error value of the initialized interpolation fitting function is calculated, and the coefficients of the interpolation fitting function are iterated until the error value of the interpolation fitting function obtained by iteration is lower than the preset error threshold. The d-th iteration formula of the coefficients of the interpolation fitting function is: ; ; ; in: Represents the iteration step size of the three coefficients, is the d-th iteration result of the three coefficients; Represents a random number between 0 and 1; Indicates the constant term preset iteration step size, Indicates the preset iteration step of a term; The error value of the interpolation fitting function obtained at the dth iteration is : ; ; As a preferred embodiment of the present invention, a radial basis function is introduced in the interpolation process to improve the smoothness of the interpolation result, and the interpolation fitting function does not have a high-order polynomial, and the oscillation problem of the high-order polynomial interpolation will not occur, and the result is more stable. The interpolation fitting function is composed of a polynomial and a radial basis function. The polynomial part can provide a supplement to the global trend, and the radial basis function part can dynamically adjust the local characteristics according to the distance between points, thereby improving the accuracy of the interpolation fitting result. The interpolation fitting function obtained by iteration is used to generate the river health status of different river locations, and the lowest river health status of each river location is retained to obtain the overall river health status assessment distribution of the target river.

[0032] It should be understood that the embodiment is for illustration only and the scope of the patent application is not limited to this structure.

[0033] It should be noted that the serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments. And the terms "including", "comprising" or any other variants thereof in this article are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "including a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0034] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0035] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A river health status assessment method based on diffusion analysis, characterized in that: The method comprises: S1: Construct a river health assessment indicator system; S2: Obtain the location of potential pollution sources and pollutant emissions of the target river, build a river pollution propagation path analysis model, and perform pollution propagation path analysis on the target river; S3: Sampling the pollution propagation path according to the preset path interval, obtaining the evaluation index value sequence of the target river in the river health evaluation index system, and using the evaluation index value sequence to evaluate the river health status at the sampling location; S4: Perform interpolation fitting on the river health status of consecutive sampling locations in the pollution propagation path to obtain the overall river health status assessment distribution of the target river.

2. A method for river health status assessment based on diffusion analysis as claimed in claim 1, characterized in that: The river health evaluation index system is constructed in step S1, including: The river health evaluation index system includes chemical property evaluation indicators and physical property evaluation indicators. The chemical property indicators include pH value index, dissolved oxygen content index, biochemical oxygen demand index, chemical oxygen demand index, nitrogen content index, phosphorus content index, ammonia nitrogen content index and heavy metal concentration index. The physical property evaluation indicators include temperature index, turbidity index, transparency index and conductivity index.

3. A method for river health status assessment based on diffusion analysis as claimed in claim 1, characterized in that: The step S2 obtains the location of the potential pollution source and the amount of pollutant discharged of the target river, including: The potential pollution source of the target river is a source that can directly discharge pollutants into the target river through a fixed discharge location, and the fixed discharge location includes a pipeline and a discharge port; The pollutant emission amount of the potential pollution source of the river is the mass of pollutants discharged into the target river by the potential pollution source of the river, wherein the pollutants are the wastewater discharged by the potential pollution source of the river.

4. A method for river health status assessment based on diffusion analysis as claimed in claim 3, characterized in that: The construction of the river pollution propagation path analysis model and the analysis of the pollution propagation path of the target river include: The river pollution propagation path analysis model takes the location of the potential pollution source of the river as input, takes the pollutant emission as the intermediate value, and takes the path where the pollutant concentration gradient change is less than the preset threshold as the pollution propagation path of the potential pollution source location of the river; The river pollution propagation path analysis model includes a target river node graph construction module, a pollutant concentration propagation module, a pollutant concentration gradient change module and a pollution propagation path generation module; The target river node graph construction module is used to construct the target river into a node graph, wherein the node graph is composed of nodes and edges. The nodes include the source of the target river, the confluence point of the tributaries, the river branch points and the location of the potential pollution source of the river. The edges describe the river flow relationship between the nodes. If there is a river between the nodes, the flow of the river is represented by an arrow. The pollutant concentration propagation module uses the pollutant discharge of the potential pollution source of the river as the intermediate value and the pollutant concentration propagation value of the downstream node of the potential pollution source position of the river in the node graph as the output; The pollutant concentration gradient change module is used to calculate the pollution gradient change value of the pollutant concentration propagation value of the adjacent nodes. The pollution gradient change value of the pollutant concentration propagation value of the adjacent nodes Node1 and Node2 is : ； in: Represents the pollutant concentration propagation value of node Node1, Indicates the pollutant concentration propagation value of node Node2; The pollution propagation path generation module is used to evaluate the pollution gradient change values ​​between multiple consecutive adjacent nodes. If the pollution gradient change values ​​are all less than a preset threshold, the river path formed by the multiple consecutive adjacent nodes is used as a set of pollution propagation paths for the potential pollution source locations of the river.

5. A method for river health status assessment based on diffusion analysis as claimed in claim 4, characterized in that: The expression of pollutant concentration propagation in the pollutant concentration propagation module is: ； in: represents an exponential function with a natural constant as base, represents the pollutant discharge of the potential pollution source of the river, t represents the preset propagation time, s represents the river flow velocity, Indicates the downstream node The distance from the potential pollution source of the river, G represents the diffusion coefficient, Indicates the downstream node The pollutant concentration propagation value after propagation time t.

6. A method for river health status assessment based on diffusion analysis as claimed in claim 1, characterized in that: In the step S3, sampling the pollution propagation path according to the preset path interval includes: The sampling weight of the pollution propagation path is calculated based on the path length of the pollution propagation path and the importance of the nodes, and the pollution propagation path is sampled in descending order of the sampling weight; Taking the starting node of the pollution propagation path as the initial sampling position and the preset path interval as the distance interval between adjacent sampling positions, the target river is sampled to obtain river water samples of the target river at different sampling positions, and the evaluation index values ​​of different indicators of the river water samples in the river health evaluation index system are measured to form a sequence of evaluation index values ​​of the target river at the sampling position.

7. A method for river health status assessment based on diffusion analysis as claimed in claim 6, characterized in that: The method of evaluating the river health status at the sampling location using the evaluation index value sequence includes: The evaluation index value sequence of the rth sampling position of the pollution propagation path is : ； in: These are the evaluation index values ​​of pH value, dissolved oxygen content, biochemical oxygen demand, chemical oxygen demand, nitrogen content, phosphorus content, ammonia nitrogen content and heavy metal concentration of the river water sample at the rth sampling position; They are the evaluation index values ​​of the temperature index, turbidity index, transparency index and conductivity index of the river water sample at the rth sampling position; , R represents the number of sampling locations along the pollution propagation path; The evaluation index value sequence is standardized by minimum-maximum normalization; A linear function is used to map the standardized evaluation index value sequence to the river health status, and the river health status of all sampling locations in the pollution propagation path is obtained. The river health status of the rth sampling location in the pollution propagation path is : ； in: Represents the evaluation index value sequence The standardized processing result of , w represents the weight coefficient in the linear function, b represents the bias coefficient in the linear function, and T represents transposition; The weight coefficient and bias coefficient in the linear function are solved by using the loss function training method. The expression of the loss function is: : ； in: Represents the parameters to be solved, including weight coefficients and bias coefficients, represents the L2 norm; represents the real river health status of the hth group of training samples, Indicates the parameters to be solved The estimated river health status of the hth group of training samples is, , H represents the total number of training samples, represents the control coefficient.

8. A method for river health status assessment based on diffusion analysis as claimed in claim 7, characterized in that: In the step S4, interpolation fitting is performed on the river health status of continuous sampling locations in the pollution propagation path, including: The interpolation fitting process is: Obtain the river health status of continuous sampling locations in the pollution propagation path to form a discrete sequence of river health status; Initializing an interpolation fitting function of a pollution propagation path, wherein the interpolation fitting function takes the distance between the river position and the position of a potential pollution source in the river as an independent variable and takes the river health status at the river position as an output; Calculate the error value of the initialized interpolation fitting function, and iterate the coefficients of the interpolation fitting function until the error value of the interpolation fitting function obtained by iteration is lower than a preset error threshold; The interpolation fitting function obtained by iteration is used to generate the river health status of different river locations, and the lowest river health status of each river location is retained to obtain the overall river health status assessment distribution of the target river.

Images