A method for evaluating the health status of rivers through diffusion analysis

Abstract

The present invention relates to the technical field of river health status assessment, and discloses a method for assessing the river health status by diffusion analysis. The method includes: obtaining the positions of potential pollution sources and pollutant emissions of the target river, and analyzing the pollution propagation path of the target river; collecting the sequence of evaluation index values in the river health evaluation index system of the target river, and using the sequence of evaluation index values to evaluate the river health status of the sampling position. The present invention conducts diffusion analysis on the pollutant emissions, obtains the pollutant concentration propagation values of the pollutants at different target river nodes, realizes the extraction of the river pollution propagation path based on diffusion analysis, evaluates the river health status of different sampling positions, and uses the interpolation fitting method to interpolate and fit the river health status of continuous sampling positions, so as to obtain the overall river health status assessment distribution describing the river health status of the target river at different positions, and accurately locate the river areas with relatively low health status.

Description

Technical Field

[0001] The present invention relates to the technical field of river health status assessment, and particularly to a method for assessing river health status by diffusion analysis. Background Art

[0002] With the development of social economy and the growth of population, the demand for water resources globally is increasing day by day. In particular, the rational management and protection of water resources have 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 status of rivers helps to detect problems in a timely manner, guide management decisions, and formulate reasonable river restoration and protection measures. Traditionally, river health assessment has mainly been carried out through means such as water quality monitoring and ecological surveys. However, these methods often can only reflect the health status of rivers locally, lacking comprehensiveness, systematicness, and persistence, and it is difficult to accurately reflect the overall health status of river ecosystems. Summary of the Invention

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

[0004] To achieve the above object, a method for assessing river health status by diffusion analysis provided by the present invention includes the following steps:

[0005] S1: Construct a river health evaluation index system;

[0006] S2: Obtain the positions of potential pollution sources and pollutant emissions of the target river, construct an analysis model for the pollution propagation path of the river, and analyze the pollution propagation path of the target river;

[0007] S3: Sample the pollution propagation path at preset path intervals to obtain a sequence of evaluation index values of the target river in the river health evaluation index system, and use the sequence of evaluation index values to evaluate the river health status at the sampling positions;

[0008] S4: Interpolate and fit the river health status at continuously sampled positions in the pollution propagation path to obtain the overall river health status assessment distribution of the target river.

[0009] As a further improvement method of the present invention:

[0010] Optionally, in the step S1 of constructing the river health evaluation index system, it includes:

[0011] The river health assessment index system includes chemical property assessment indexes and physical property assessment 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 assessment indexes include temperature index, turbidity index, transparency index, and conductivity index.

[0012] Optionally, obtaining the potential pollution source location and pollutant emission amount of the target river in step S2 includes:

[0013] The potential pollution source of the target river is the source that can directly discharge pollutants into the target river through a fixed discharge location. The fixed discharge location includes pipelines and discharge outlets;

[0014] The pollutant emission amount of the potential pollution source of the river is the mass of pollutants discharged by the potential pollution source of the river into the target river, where the pollutants are the wastewater discharged by the potential pollution source of the river.

[0015] Optionally, constructing a river pollution propagation path analysis model to analyze the pollution propagation path of the target river includes:

[0016] The river pollution propagation path analysis model takes the potential pollution source location of the river as the input, takes the pollutant emission amount as the intermediate value, and takes the path with the change in pollutant concentration gradient less than the preset threshold as the pollution propagation path of the potential pollution source location of the river;

[0017] The river pollution propagation path analysis model includes a target river node map construction module, a pollutant concentration propagation module, a pollutant concentration gradient change module, and a pollution propagation path generation module;

[0018] The target river node map construction module is used to construct the target river into a node map, where the node map is composed of nodes and edges. The nodes include the river source, tributary confluence point, river branch point, and potential pollution source location of the target river. The edges describe the river flow relationship between the nodes. If there is a river between the nodes, an arrow is used to represent the flow of the river;

[0019] The pollutant concentration propagation module takes the pollutant emission amount of the potential pollution source of the river as the intermediate value and outputs the pollutant concentration propagation value of the downstream node of the potential pollution source location in the node map;

[0020] The pollutant concentration gradient change module is used to calculate the pollution gradient change value of the pollutant concentration propagation values of adjacent nodes. The pollution gradient change value of the pollutant concentration propagation values of the adjacent nodes Node1 and Node2 is :

[0021] ;

[0022] Wherein:

[0023] represents the pollutant concentration propagation value of node Node1, represents the pollutant concentration propagation value of node Node2;

[0024] The pollution propagation path generation module is used to evaluate the pollution gradient change value between continuously multiple adjacent nodes. If the pollution gradient change values are all less than a preset threshold, the river path formed by the continuously multiple adjacent nodes is used as a set of pollution propagation paths for the potential pollution source location of the river.

[0025] Optionally, the expression of pollutant concentration propagation in the pollutant concentration propagation module is:

[0026] ;

[0027] Wherein:

[0028] represents the exponential function with the natural constant as the base, represents the pollutant emission 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 between and the potential pollution source location of the river, G represents the diffusion coefficient, represents the downstream node the pollutant concentration propagation value after propagating for t time.

[0029] Optionally, in step S3, sampling the pollution propagation paths at preset path intervals includes:

[0030] Calculating the sampling weight of the pollution propagation path based on the path length of the pollution propagation path and the node importance, and sampling the pollution propagation paths in the order from high to low of the sampling weight;

[0031] Taking the path starting node of the pollution propagation path as the initial sampling position, using the preset path interval as the distance interval between adjacent sampling positions, sampling the target river to obtain the river water samples at different sampling positions of the target river, and measuring the evaluation index values of different indexes in the river health evaluation index system for the river water samples to form the evaluation index value sequence at the sampling positions of the target river. The river water sample at each sampling position is 100 milliliters.

[0032] Optionally, using the evaluation index value sequence to evaluate the river health status of the sampling position includes:

[0033] The evaluation index value sequence at the r-th sampling position of the pollution propagation path is :

[0034] ;

[0035] Wherein:

[0036] are the evaluation index values of the river water sample at the r-th sampling position for the 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, respectively;

[0037] are the evaluation index values of the river water sample at the r-th sampling position for the temperature index, turbidity index, transparency index, and conductivity index, respectively;

[0038] , and R represents the number of sampling positions of the pollution propagation path;

[0039] Perform standardization processing on the evaluation index value sequence, and the method of the standardization processing is min-max normalization;

[0040] Use a linear function to map the standardized evaluation index value sequence to the river health status, and obtain the river health status of all sampling positions in the pollution propagation path. The river health status of the r-th sampling position in the pollution propagation path is :

[0041] ;

[0042] Wherein:

[0043] represents the standardized processing result of the evaluation index value sequence , w represents the weight coefficient in the linear function, b represents the bias coefficient in the linear function, and T represents the transpose;

[0044] Solve the weight coefficient and bias coefficient in the linear function by means of training with a loss function. The expression of the loss function is :

[0045] ;

[0046] Wherein:

[0047] represents the parameter to be solved, including the weight coefficient and the bias coefficient, represents the L2 norm;

[0048] represents the true river health status of the h-th group of training samples, represents the parameter to be solved the estimated river health status of the h-th group of training samples below, , H represents the total number of training samples, represents the regulation coefficient.

[0049] Optionally, in the step S4, interpolating and fitting the river health status at consecutive sampling positions in the pollution propagation path includes:

[0050] The interpolation and fitting process is as follows:

[0051] Obtain the river health status at consecutive sampling positions in the pollution propagation path to form a discrete sequence of river health status;

[0052] Initialize the interpolation and fitting function of the pollution propagation path, where the independent variable of the interpolation and fitting function is the distance between the river position and the potential pollution source position of the river, and the output is the river health status of the river position;

[0053] Calculate the error value of the initialized interpolation and fitting function, and iterate the coefficients of the interpolation and fitting function until the error value of the iteratively obtained interpolation and fitting function is lower than the preset error threshold;

[0054] Use the iteratively obtained interpolation and fitting function to generate the river health status at different river positions, and retain the lowest river health status at each river position to obtain the overall river health status assessment distribution of the target river.

[0055] To solve the above problems, the present invention provides an electronic device, which includes:

[0056] A memory that stores at least one instruction;

[0057] A communication interface that enables communication of the electronic device; and

[0058] A processor that executes the instructions stored in the memory to implement the above-mentioned river health status assessment method for diffusion analysis.

[0059] To solve the above problems, the present invention also provides a computer-readable storage medium, in which at least one instruction is stored, and the at least one instruction is executed by a processor in an electronic device to implement the above-mentioned river health status assessment method for diffusion analysis.

[0060] Compared with the prior art, the present invention proposes a river health status assessment method for diffusion analysis, and this technology has the following advantages:

[0061] First, this solution proposes a method for analyzing the diffusion of river pollution. Based on the locations of potential pollution sources in the target river, it conducts a diffusion analysis of pollutant emissions to obtain the pollutant concentration propagation values at different target river nodes, and calculates the pollution gradient change values between adjacent target river nodes. The river path composed of multiple target river nodes with pollution gradient changes less than the preset threshold is taken as a set of pollution propagation paths for the locations of potential pollution sources in the river, realizing the extraction of river pollution propagation paths based on diffusion analysis. Then, based on the importance of the pollution propagation paths, sampling weights are calculated, and the pollution propagation paths are sampled in descending order of the sampling weights to obtain water samples of the river at different sampling positions for each set of pollution propagation paths.

[0062] Meanwhile, this solution proposes a method for evaluating the overall health status of a river. It measures the water samples of the river based on the river health evaluation index system to obtain the evaluation index values representing the health degree of the target river, and converts the evaluation index values into the river health status at the sampling positions. The interpolation fitting method is used to interpolate and fit the river health status at continuous sampling positions. During the interpolation process, a radial basis function is introduced to improve the smoothness of the interpolation result, and the interpolation fitting function does not contain high-order polynomials, so there will be no oscillation problem of high-order polynomial interpolation, and the result is more stable. Moreover, 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, while the radial basis function part can dynamically adjust the local characteristics according to the distance between points to improve the accuracy of the interpolation fitting result, obtaining the overall river health status evaluation distribution describing the river health status at different positions of the target river and accurately locating the river areas with lower health status. Description of the Drawings

[0063] Figure 1 It is a schematic flowchart of a method for evaluating the health status of a river by diffusion analysis provided in an embodiment of the present invention.

[0064] The realization, functional features, and advantages of the purpose of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0065] 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.

[0066] An embodiment of the present application provides a method for evaluating the health status of a river through diffusion analysis. The execution subject of the method for evaluating the health status of a river through diffusion analysis includes, but is not limited to, at least one of electronic devices such as a server, a terminal, etc. 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 through 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.

[0067] Referring to Figure 1 , Embodiment 1 of the present invention is:

[0068] A method for evaluating the health status of a river through diffusion analysis includes the following steps:

[0069] S1: Construct a river health evaluation index system.

[0070] In the S1 step of constructing the river health evaluation index system, it includes:

[0071] 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;

[0072] Specifically, a thermometer, a turbidimeter, a Secchi disk, and a conductivity meter can be used to measure the evaluation index values of the physical property evaluation indexes of the river water sample, a pH test paper can be used to measure the evaluation index value of the pH value index of the river water sample, a dissolved oxygen meter can be used to measure the evaluation index value of the dissolved oxygen content index of the river water sample, the potassium dichromate method can be used to measure the evaluation index value of the chemical oxygen demand index of the river water sample, and the reduction amount of dissolved oxygen after culturing the river water sample for 5 days can be measured as the evaluation index value of the biochemical oxygen demand index.

[0073] S2: Obtain the potential pollution source locations and pollutant emissions of the target river, construct a river pollution propagation path analysis model, and conduct a pollution propagation path analysis on the target river.

[0074] In the S2 step of obtaining the potential pollution source locations and pollutant emissions of the target river, it includes:

[0075] The potential pollution sources of the target river are the sources that can directly discharge pollutants into the target river through fixed discharge locations. The fixed discharge locations include pipelines and discharge outlets;

[0076] As an embodiment of the present invention, the pollution sources include chemical plants, paper mills, pharmaceutical factories, textile mills, residential areas, livestock and poultry farms, aquaculture farms, and power plants located near the target river;

[0077] The pollutant emissions of the potential pollution sources in the river refer to the mass of pollutants discharged from the potential pollution sources in the river into the target river, where the pollutants are the wastewater discharged from the potential pollution sources in the river.

[0078] Constructing a river pollution propagation path analysis model to analyze the pollution propagation path of the target river includes:

[0079] The river pollution propagation path analysis model takes the location of the potential pollution sources in the river as the input, takes the pollutant emissions as the intermediate value, and regards the path with the change of pollutant concentration gradient less than the preset threshold as the pollution propagation path of the location of the potential pollution sources in the river;

[0080] 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;

[0081] The target river node graph construction module is used to construct the target river into a node graph, where the node graph is composed of nodes and edges. The nodes include the river source, tributary confluence point, river branch point, and the location of the potential pollution sources in the target river. The edges describe the river flow relationship between the nodes. If there is a river between the nodes, an arrow is used to represent the flow of the river;

[0082] The pollutant concentration propagation module takes the pollutant emissions of the potential pollution sources in the river as the intermediate value and outputs the pollutant concentration propagation value of the downstream nodes of the location of the potential pollution sources in the node graph;

[0083] The pollutant concentration gradient change module is used to calculate the pollution gradient change value of the pollutant concentration propagation values of adjacent nodes. The pollution gradient change value of the pollutant concentration propagation values of the adjacent nodes Node1 and Node2 is :

[0084] ;

[0085] Where:

[0086] represents the pollutant concentration propagation value of node Node1, represents the pollutant concentration propagation value of node Node2;

[0087] The pollution propagation path generation module is used to evaluate the pollution gradient change values between a series of consecutive adjacent nodes. If all the pollution gradient change values are less than a preset threshold, the river path formed by the series of consecutive adjacent nodes is taken as a set of pollution propagation paths for the potential pollution source locations 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 recording.

[0088] The expression for pollutant concentration propagation in the pollutant concentration propagation module is as follows:

[0089] ;

[0090] Where:

[0091] represents the exponential function with the natural constant as the base, represents the pollutant emission 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 between and the potential pollution source location of the river, G represents the diffusion coefficient, represents the downstream node the pollutant concentration propagation value after propagating for t time.

[0092] S3: Sample the pollution propagation paths at preset path intervals to obtain a sequence of evaluation index values of the target river in the river health evaluation index system, and use the sequence of evaluation index values to evaluate the river health status at the sampling locations.

[0093] The step of sampling the pollution propagation paths at preset path intervals in the S3 step includes:

[0094] Calculate the sampling weights of the pollution propagation paths based on the path lengths and node importance of the pollution propagation paths, and sample the pollution propagation paths in the order from high to low of the sampling weights;

[0095] Take the path start node of the pollution propagation path as the initial sampling location, use the preset path interval as the distance interval between adjacent sampling locations, sample the target river to obtain the river water samples at different sampling locations of the target river, measure the evaluation index values of different indicators in the river health evaluation index system for the river water samples, and form a sequence of evaluation index values of the target river at the sampling locations. The river water sample at each sampling location is 100 ml.

[0096] As a preferred embodiment of the present invention, based on the number of pollution propagation paths associated with the nodes in the pollution propagation path, where the larger the number, the more the node is a super pollution propagator of potential pollution sources in the river, thereby measuring the importance of the pollution propagation path in the pollution propagation process, and using the proportion of the river path passing through the pollution propagation path as the proportion of the river flow task undertaken by the pollution propagation path in the target river node graph. The higher the proportion, the more the number of target river nodes connected by the pollution propagation path. The sampling weight calculation formula of the pollution propagation path Load is:

[0097] ;

[0098] Where:

[0099] represents the sampling weight of the pollution propagation path Load;

[0100] represents the number of pollution propagation paths including the m-th node in the pollution propagation path Load, represents the number of nodes in the target river node graph, , M represents the number of nodes in the pollution propagation path Load;

[0101] represents the node set in the target river node graph, represents passing through the node the number of river paths, represents passing through the node Among the river paths, the number of river paths including the pollution propagation path Load.

[0102] Evaluating the river health status of the sampling location using the evaluation index value sequence includes:

[0103] The evaluation index value sequence of the r-th sampling location of the pollution propagation path is :

[0104] ;

[0105] Where:

[0106] are the evaluation index values of the river water sample at the r-th sampling location in the 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 in sequence;

[0107] are the evaluation index values of the river water sample at the r-th sampling location in the temperature index, turbidity index, transparency index, and conductivity index in sequence;

[0108] , where R represents the number of sampling positions of the pollution propagation path;

[0109] Perform normalization processing on the evaluation index value sequence, and the normalization processing method is min-max normalization;

[0110] Use a linear function to map the normalized evaluation index value sequence to the river health status, and obtain the river health status of all sampling positions in the pollution propagation path. The river health status of the r-th sampling position in the pollution propagation path is :

[0111] ;

[0112] Where:

[0113] represents the evaluation index value sequence of the normalization processing result, w represents the weight coefficient in the linear function, b represents the bias coefficient in the linear function, and T represents the transpose;

[0114] Solve the weight coefficient and bias coefficient in the linear function by using the training method of the loss function. The expression of the loss function is :

[0115] ;

[0116] Where:

[0117] represents the parameters to be solved, including the weight coefficient and the bias coefficient, represents the L2 norm;

[0118] represents the true river health status of the h-th group of training samples, represents the parameters to be solved the estimated river health status of the h-th group of training samples under , H represents the total number of training samples, represents the regulation coefficient. As a preferred embodiment of the present invention,

[0119] Specifically, one or a combination of algorithms such as the gradient descent algorithm, the Lagrange method, and the Newton iteration method can be used to solve the loss function.

[0120] S4: Interpolate and fit the river health status of consecutive sampling positions in the pollution propagation path to obtain the overall river health status evaluation distribution of the target river.

[0121] In the step S4, interpolation fitting is performed on the river health status at consecutive sampling positions in the pollution propagation path, including:

[0122] The interpolation fitting process is as follows:

[0123] Obtain the river health status at consecutive sampling positions in the pollution propagation path to form a discrete sequence of river health status:

[0124] ;

[0125] Where:

[0126] represents the distance between the nth sampling position in the pollution propagation path and the location of the river potential pollution source, represents the river health status at the nth sampling position in the pollution propagation path, , N represents the total number of sampling positions in the pollution propagation path;

[0127] Initialize the interpolation fitting function for the pollution propagation path. The interpolation fitting function takes the distance between the river location and the location of the river potential pollution source as the independent variable and the river health status at the river location as the output. The initialized interpolation fitting function is:

[0128] ;

[0129] Where:

[0130] represents the initialized interpolation fitting function, represents the independent variable, represents the river health status at the river location at a distance of from the location of the river potential pollution source, represents the coefficient of the initialized interpolation fitting function;

[0131] 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 iterated interpolation fitting function is lower than the preset error threshold. The d-th iteration formula for the coefficients of the interpolation fitting function is:

[0132] ;

[0133] ;

[0134] ;

[0135] Where:

[0136] represents the iteration step sizes of the three coefficients, is the d-th iteration result of three coefficients;

[0137] represents a random number between 0 and 1;

[0138] represents the preset iteration step of the constant term, represents the preset iteration step of the linear term;

[0139] The error value of the interpolation fitting function obtained by the d-th iteration is :

[0140] ;

[0141] ;

[0142] As a preferred embodiment of the present invention, a radial basis function is introduced during the interpolation process to improve the smoothness of the interpolation result, and the interpolation fitting function does not contain high-order polynomials, so there will be no oscillation problem of high-order polynomial interpolation, the result is more stable, and 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, while the radial basis function part can dynamically adjust the local characteristics according to the distance between points to improve the accuracy of the interpolation fitting result;

[0143] Use the interpolation fitting function obtained by iteration to generate the river health status at different river positions, retain the lowest river health status at each river position, and obtain the assessment distribution of the overall river health status of the target river.

[0144] It should be understood that the above embodiments are only for illustration purposes and are not limited by this structure in the scope of the patent application.

[0145] 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 or disadvantages of the embodiments. And the term "including" in this article, "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, so that a process, apparatus, article or method including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such a process, apparatus, article or method. Without further limitation, an element defined by the statement "including a..." does not exclude the presence of additional identical elements in the process, apparatus, article or method including the element.

[0146] Through the description of the above embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above and includes several instructions for causing a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of the present invention.

[0147] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for evaluating the health status of a river in diffusion analysis, characterized in that, The method includes: S1: Construct a river health assessment index system; S2: Obtain the locations of potential pollution sources and pollutant emissions of the target river, construct an analysis model for the river pollution propagation path, and analyze the pollution propagation path of the target river; The river pollution propagation path analysis model takes the locations of potential pollution sources of the river as input, uses the pollutant emissions as the intermediate value, and takes the path with a change in pollutant concentration gradient less than a preset threshold as the pollution propagation path of the locations of potential pollution sources 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, where the node graph consists of nodes and edges. The nodes include the river source, tributary confluence points, river bifurcation points, and locations of potential pollution sources of the target river. The edges describe the river flow relationship between the nodes. If there is a river between the nodes, an arrow is used to represent the river flow; The pollutant concentration propagation module takes the pollutant emissions of the potential pollution source of the river as the intermediate value and outputs the pollutant concentration propagation value of the downstream nodes of the location of the potential pollution source in the node graph; The pollutant concentration gradient change module is used to calculate the pollution gradient change value of the pollutant concentration propagation value between adjacent nodes. The pollution gradient change value of the pollutant concentration propagation value between the adjacent nodes Node1 and Node2 is : ； Where: Represents the pollutant concentration propagation value of node Node1, Represents 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 the preset threshold, the river path formed by the multiple consecutive adjacent nodes is taken as a set of pollution propagation paths of the location of the potential pollution source of the river; The expression for pollutant concentration propagation in the pollutant concentration propagation module is: ； Where: represents the exponential function with the base of the natural constant, represents the pollutant emission of the potential pollution source of the river, t represents the preset propagation time, and s represents the river flow velocity, represents the downstream node the distance between the potential pollution source location of the river, and G represents the diffusion coefficient, represents the downstream node the pollutant concentration propagation value after t time of propagation; S3: Sample the pollution propagation paths at preset path intervals to obtain a sequence of evaluation index values of the target river in the river health assessment index system, and use the sequence of evaluation index values to evaluate the river health status of the sampling locations, including: calculating the sampling weight of the pollution propagation path based on the path length and node importance of the pollution propagation path, and sampling the pollution propagation paths in descending order of the sampling weight; Taking the starting node of the pollution propagation path as the initial sampling location, using the preset path interval as the distance interval between adjacent sampling locations, sampling the target river to obtain river water samples at different sampling locations of the target river, measuring the evaluation index values of different indicators of the river water samples in the river health assessment index system, and forming a sequence of evaluation index values of the target river at the sampling locations; Based on the number of pollution propagation paths associated with the nodes in the pollution propagation path, where the larger the number, the more it indicates that the node is a super pollution propagator of the potential pollution source of the river, thereby measuring the importance of the pollution propagation path in the pollution propagation process, and using the proportion of the river path passing through the pollution propagation path as the proportion of the river flow task borne by the pollution propagation path in the target river node graph. The higher the proportion, the more it indicates that the number of target river nodes connected by the pollution propagation path is larger. The sampling weight calculation formula of the pollution propagation path Load is: ； Where: Indicates the sampling weight of the pollution propagation path Load; represents the number of pollution propagation paths that contain the m-th node in the pollution propagation path Load, represents the number of nodes in the target river node graph, , M represents the number of nodes in the pollution propagation path Load; Denote the set of nodes in the target river node graph, Denote the number of river paths passing through node ; Denote the number of river paths among the river paths passing through node that contain the pollution propagation path Load; S4: Interpolate and fit the river health status at consecutive sampling locations in the pollution propagation path to obtain the assessment distribution of the overall river health status of the target river.

2. The river health status assessment method for diffusion analysis according to claim 1, wherein In the S1 step, a river health evaluation index system is constructed, including: The river health evaluation index system includes chemical property evaluation indexes and physical property evaluation indexes. The chemical property evaluation 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.

3. The method for evaluating the health status of a river for diffusion analysis according to claim 1, characterized in that, In the S2 step, the potential pollution source locations and pollutant emissions of the target river are obtained, including: The potential pollution source of the target river is the source that can directly discharge pollutants into the target river through fixed discharge locations. The fixed discharge locations include pipelines and discharge outlets; The pollutant emissions of the potential pollution source of the river are the mass of pollutants discharged by the potential pollution source of the river into the target river, where the pollutants are the wastewater discharged by the potential pollution source of the river.

4. The method for evaluating the health status of a river for diffusion analysis according to claim 1, characterized in that, Evaluating the river health status of the sampling location using the evaluation index value sequence includes: The evaluation index value sequence of the r-th sampling position of the pollution propagation path is : ； Wherein: They are, in sequence, the evaluation index values of the river water sample at the r-th sampling position for the 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; They are the evaluation index values of the river water sample at the r-th sampling position for the temperature index, turbidity index, transparency index, and conductivity index, respectively; , where R represents the number of sampling locations of the pollution propagation path; Perform standardization processing on the evaluation index value sequence, and the standardization processing method is min-max normalization; The evaluation index value sequence after standardization is mapped to the river health status by using a linear function to obtain the river health status of all sampling locations in the pollution propagation path. The river health status of the r-th sampling location in the pollution propagation path is :[[-END]] ； Wherein: Denote the standardized processing result of the evaluation index value sequence , w represents the weight coefficient in the linear function, b represents the bias coefficient in the linear function, and T represents the transpose; The weight coefficient and bias coefficient in the linear function are solved by using the training method of the loss function, and the expression of the loss function is :[[]]END]] ； Wherein: Represents the parameter to be solved, including the weight coefficient and the bias coefficient, Represents the L2 norm; represents the true river health status of the h-th group of training samples, represents the parameter to be solved the estimated river health status of the h-th group of training samples under , H represents the total number of training samples, represents the regulation coefficient.

5. The method for evaluating the river health status of diffusion analysis according to claim 4, wherein In the S4 step, interpolating and fitting the river health status at consecutive sampling locations in the pollution propagation path includes: The interpolation and fitting process is as follows: Obtain the river health status at consecutive sampling locations in the pollution propagation path to form a discrete sequence of river health status; Initialize the interpolation and fitting function of the pollution propagation path. The interpolation and fitting function takes the distance between the river location and the potential pollution source location of the river as the independent variable and the river health status of the river location as the output; Calculate the error value of the initialized interpolation and fitting function, and iterate the coefficients of the interpolation and fitting function until the error value of the interpolated and fitted function obtained by iteration is lower than the preset error threshold; Use the interpolated and fitted function obtained by iteration to generate the river health status of different river locations, and retain the lowest river health status of each river location to obtain the assessment distribution of the overall river health status of the target river.

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