A method and system for calculating urban water pollutant balance

Abstract

The present invention discloses a method and system for calculating the balance of urban water pollutants. First, a basic database of water pollutants in a target city is constructed. Then, based on the basic database of water pollutants, an overall balance calculation of regional water pollutants is performed and the results of the regional water pollutant overall balance calculation are obtained. Then, an in-situ control experiment is carried out on the drainage system and a pipeline-river multi-factor monitoring system is established for monitoring. Then, an integrated numerical model of the pipe network-outlet-river is constructed and the water pollutants are spatially and temporally distributed in the balance process of generation-discharge-into-river. The present invention realizes the function of accurately calculating the water pollutant balance of the urban drainage system by integrating the triangle diagram method, the in-situ observation method and the numerical model method. It not only avoids the distortion of the model debugging caused by the error of the pipe network structure, but also better reflects the dynamic evolution process of water pollutants. It is of great significance for guiding the precise prevention and control of urban water pollution and the targeted treatment of the water environment, and is suitable for wide promotion and use.

Description

Technical Field

[0001] The present invention relates to the technical field of water pollutant balance calculation, and specifically to a method and system for urban water pollutant balance calculation. Background Art

[0002] Urban drainage systems are an indispensable lifeline for modern cities. An efficient, comprehensive, and sustainable drainage system is crucial for ensuring urban safety, improving the living environment, protecting the ecological environment, and ensuring the sustainable use of water resources. Faced with the dual pressures of climate change and urbanization, building a modern drainage system that is "green, resilient, and smart" is the future direction of development. Urban drainage systems typically utilize a variety of different models, including diversion, confluence, and direct discharge, as well as their respective combinations.

[0003] At present, due to the complexity of urban drainage systems and the fact that most of them are located in underground spaces, and the hidden and uncertain nature of misconnections, missed connections, mixed connections and leakages in pipe networks, urban drainage systems generally experience the coexistence of combined sewer overflows into rivers and river water backflowing into combined sewers through overflow ports. This not only makes it difficult to accurately and quantitatively measure the amount of water pollutants entering rivers from urban drainage systems, but also seriously restricts the precise tracing of pollution in complex urban water systems under the background of rapid urbanization. This has become a key issue in improving urban water environment. Therefore, it is necessary to design a method and system for measuring the balance of urban water pollutants. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to better and effectively solve the problems that the existing urban drainage system is complex and mostly located in underground space, and the misconnections, missed connections, mixed connections and leakages of the pipe network are hidden and uncertain, which leads to the coexistence of combined pipe overflow into the river and river water backflowing into the combined pipe through the overflow port in the urban drainage system. It is not only difficult to accurately and quantitatively measure the amount of water pollutants entering the river from the urban drainage system, but also seriously restricts the problem of accurate tracing of pollution in the complex urban water system under the background of rapid urbanization. A method and system for measuring the balance of urban water pollutants is provided, which realizes the function of accurately measuring the balance of water pollutants in the urban drainage system with an integrated triangle diagram method, in-situ observation method and numerical model method, and can timely correct the pipe network topology structure and verify the pipe network-river hydrodynamic numerical calibration, which not only avoids the distortion of model debugging caused by pipe network structure errors, but also better reflects the dynamic evolution process of water pollutants, which is of great significance for guiding the precise prevention and control of urban water pollution and targeted treatment of water environment.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for calculating the balance of urban water pollutants comprises the following steps:

[0007] Step A: construct a basic database of water pollutants in target cities;

[0008] Step B: Based on the basic water pollutant database, the pollution reduction coefficient method and the proportional coefficient method are used to calculate the wastewater generation volume of each industry and the direct wastewater discharge volume of the plot, and the chemical mass and water volume balance equation is used to calculate the equivalent wastewater treatment volume. The flow curve is then segmented using the triangle diagram method to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation results of regional water pollutants;

[0009] Step C: Conducting in-situ control experiments on the drainage system and establishing a pipeline-river multi-factor monitoring system to monitor the system, thereby obtaining monitoring data. Based on the monitoring data, quantitative analysis is then performed to determine the relationship between the changes in the river water level and the pipe network level, and the topological relationship between the pipe network and the river is corrected.

[0010] Step D: constructing a drainage system pipeline-outlet-river integrated numerical model using the revised topological relationship between the pipeline network and the river, and then calibrating and verifying the model parameters of the pipeline-outlet-river integrated numerical model using the monitoring data to obtain a verified pipeline-outlet-river integrated numerical model;

[0011] Step E: Use the overall balance calculation results of regional water pollutants and the verified integrated numerical model of pipe network, outlet and river to quantitatively calculate the balance of urban water pollutants in time and space and obtain the quantitative calculation results of urban water pollutant balance, thereby completing the urban water pollutant balance calculation operation.

[0012] The aforementioned method for calculating the balance of urban water pollutants includes, in step A, constructing a basic database of water pollutants in a target city, wherein the basic database includes static data and dynamic data, wherein the static data includes population size data, land use area data, pipe network vector data, river vector data, outlet data, and pump station data of the target city, and the dynamic data includes urban residential tap water sales volume, industrial and service water sales volume, special industry water sales volume, daily rainfall, sewage online monitoring data of enterprises with online monitoring, water use and discharge data of enterprises without online monitoring, sewage treatment volume of urban sewage treatment plants, and COD concentration of sewage treatment plant influent, wherein the urban residential tap water sales volume includes residential water sales volume, non-residential water sales volume, secondary water supply sales volume, and special poverty preferential water sales volume;

[0013] The specific construction process of the water pollutant basic database is to decompose the dynamic data according to the water supply division of the water plant and the drainage division of the sewage treatment plant and in combination with the population size data and land use area data of each administrative unit of the target city.

[0014] The above-mentioned method for calculating the balance of urban water pollutants, step B, based on the basic database of water pollutants, uses the pollution reduction coefficient method and the proportional coefficient method to respectively calculate the sewage generation of each industry and the direct discharge of sewage from the plot, and uses the chemical mass and water balance equation to calculate the equivalent sewage treatment volume, and then uses the triangle graphic method to divide the flow curve to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation result of regional water pollutants, wherein the overall balance calculation result of regional water pollutants includes sewage generation, sewage treatment, direct discharge of sewage and the amount of external water entering the pipe network. The specific steps are as follows,

[0015] Step B1, using the pollution reduction coefficient method to calculate the amount of wastewater generated by each industry, where the amount of wastewater generated is equal to the product of water consumption and the corresponding pollution reduction coefficient;

[0016] Among them, the pollution reduction coefficient for urban domestic water use is 0.8-0.9, the pollution reduction coefficient for industrial water use is 0.78, and the pollution reduction coefficients for the service industry and special industries are 0.82 and 0.9 respectively;

[0017] Step B2, using the proportional coefficient method to calculate the direct discharge volume of sewage from each industry plot, wherein the direct discharge volume of sewage from the plot is specifically calculated using the product volume of the plot and the direct discharge coefficient estimated based on the pipe network;

[0018] Among them, the direct discharge rate for communities without pipe networks is 100%, and the direct discharge rate for communities with pipe networks but mixed connections to balcony risers and first-floor garages is 4%.

[0019] Step B3, use the chemical mass and water balance equation to calculate the equivalent sewage treatment capacity. Specifically, the chemical mass and water balance relationship of the drainage system water quality characteristic factor is used to calculate the equivalent sewage treatment capacity of the urban sewage treatment plant. The chemical oxygen demand (COD) is used instead of water volume as the calculation factor and the chemical mass and water balance equation is used for calculation. The calculation process is shown in formula (1).

[0020] ,

[0021] (1)

[0022] in, is the total sewage inflow flow of the sewage treatment plant under dry flow conditions, is the amount of raw sewage, is the inflow and infiltration of external water, including groundwater and surface water, 、 and They are the concentrations of water quality characteristic factors of total sewage, primary sewage and external water under dry flow conditions;

[0023] Step B4. Use the triangular graphical method to divide the flow curve to measure the amount of external water flowing into the pipe network. Specifically, divide the flow curve at the outlet of the sewage pipe network during the corresponding time period according to the chemical mass and water volume balance equations, and then arrange the daily flow values within the selected time period at the end of the sewage pipe network in ascending order to form an S-shaped curve.

[0024] Among them, the percentage P of the amount of external water flowing into the pipe network in the influent volume of the sewage treatment plant can divide the evaluation level of the external water problem into four levels, including general (P < 15%), relatively serious (15% < P < 35%), serious (35% <= P < 55%), and extremely serious (P >= 55%);

[0025] For the aforementioned method for calculating the balance of urban water pollutants, in step C, conduct in-situ control experiments on the drainage system and establish a multi-element monitoring system for pipelines and rivers for monitoring to obtain monitoring data, and then quantitatively analyze the response relationship between the changes in river water level and pipeline liquid level and correct the topological relationship between the pipeline and the river according to the monitoring data. The specific steps are as follows.

[0026] Step C1. Conduct in-situ control experiments on the drainage system. Specifically, use the method of controlling variables to regulate the river water level and pipeline liquid level respectively. The specific steps are as follows.

[0027] Step C11. Control the river water level. Specifically, first start the river pumping station and lower the river water level, then adjust the pumping flow of the pumping station and maintain the river water level, then close the pumping station and monitor the slow process of water level rise, then open the water replenishment gate and monitor the obvious process of river water level rise, and then increase the opening of the gate and monitor the accelerated process of water level rise;

[0028] Step C12. Control the pipeline sewage lift pump station. Specifically, first close one sewage lift pump station, then close another sewage lift pump station, then close one sewage lift pump station, and then close all integrated pump stations. At the same time, monitor the change process of the pipeline liquid level;

[0029] Step C13. Control the airbag blockage. Specifically, block the sewage intercepting pipes on both sides of the river with airbags and clarify the blocking points for blocking according to the actual situation, and then divide the pipeline into two independent pipelines and monitor the changes in the pipeline liquid level of the two pipelines under the superposition of the river water level control respectively;

[0030] Step C14. Control the pipeline branch. Specifically, block the connected multiple pipelines with airbags, and then control the different diversion ports of the pipe sections and monitor the changes in the liquid levels of different pipe sections separately;

[0031] Step C2. Establish a multi-element monitoring system for pipelines and rivers for monitoring. Among them, the multi-element monitoring system for pipelines and rivers is specifically to monitor the pipeline liquid level, river water level, diversion port flow, and video during the in-situ control experiment of the drainage system. The specific steps are as follows.

[0032] Step C21: Monitoring the pipeline liquid level and river water level. Specifically, each target pipeline is monitored using a pipeline liquid level gauge, and each target river is monitored upstream and downstream using a river float level gauge. The river water level near the sewage well is also monitored simultaneously.

[0033] Step C22: monitoring the flow rate at the pipeline junction, specifically installing a fixed flow meter on site when encountering a pipe network bifurcation;

[0034] Step C23: Pipeline video monitoring, using a closed-circuit television monitoring system to endoscopically detect abnormal pipeline seepage.

[0035] In the aforementioned method for calculating the balance of urban water pollutants, step D is to construct a drainage system pipe network-outlet-river integrated numerical model using the corrected topological relationship between the pipe network and the river, and then calibrate and verify the model parameters of the pipe network-outlet-river integrated numerical model using monitoring data to obtain a verified pipe network-outlet-river integrated numerical model. The specific steps are as follows:

[0036] Step D1, constructing a drainage system pipe network-outlet-river integrated numerical model using the revised topological relationship between the pipe network and the river, wherein the pipe network-outlet-river integrated numerical model includes a rainfall runoff module, a pipe flow calculation module, a water quality module, and a real-time control module;

[0037] Step D2, using monitoring data to calibrate and verify the model parameters of the pipeline-outlet-river channel integrated numerical model and obtain the verified pipeline-outlet-river channel integrated numerical model, wherein the calibration and verification indicators use the Nash efficiency coefficient NSE, the deviation percentage PBIAS and the ratio coefficient RSR of the root mean square error to the observation standard deviation, the Nash efficiency coefficient NSE is used to quantify the measurement accuracy of the pipeline-outlet-river channel integrated numerical model by using the relative size of the residual variance and the measurement data variance, the deviation percentage PBIAS is used to measure the average trend of the data deviating from the observed data, and the ratio coefficient RSR of the root mean square error to the observation standard deviation is used to standardize the root mean square error by using the standard deviation of the observed value.

[0038] Among them, the Nash efficiency coefficient NSE takes a value in the range of (-∞, 1]. The closer it is to 1, the better the model's prediction ability is. The closer the deviation percentage PBIAS is to 0, the more accurate the measurement effect is. A positive value indicates that the model has an underestimated bias, and vice versa, an overestimated bias occurs. The closer the ratio coefficient RSR of the root mean square error to the observed standard deviation is to 0, the better the model simulation performance is. If the Nash efficiency coefficient NSE is greater than 0.5 and the ratio coefficient RSR of the root mean square error to the observed standard deviation is greater than 0.5, the model simulation performance is better. 0.7, and the percentage bias PBIAS of runoff and pollutant calculations are and , it means that the measurement effect is relatively reliable;

[0039] The specific steps of step D1 of the above-mentioned method for calculating the balance of urban water pollutants are as follows:

[0040] Step D11: constructing a rainfall runoff module, wherein the rainfall runoff module adopts the Horton infiltration formula, as shown in formula (2):

[0041] (2)

[0042] in, is the infiltration rate, To stabilize the infiltration rate, is the initial infiltration rate, For rainfall time, is the decay constant;

[0043] Step D12: construct a pipe flow calculation module, wherein the pipe flow calculation module adopts the Saint-Venant equations of open channel unsteady flow partial differential equations. The specific steps are as follows:

[0044] Step D121, establish the mass conservation equation and momentum conservation equation, as shown in formula (3),

[0045] ,

[0046] (3);

[0047] in, For traffic, is the cross-sectional area, is the acceleration due to gravity, is the horizontal angle, is the bed slope, is the delivery volume;

[0048] In step D122, the steady flow of the river is calculated using the Manning formula, as shown in formula (4):

[0049] (4)

[0050] in, is the roughness, is the hydraulic radius, It is the bottom slope of the river channel;

[0051] Step D13: constructing a water quality module, wherein the water quality module uses a one-dimensional convection-diffusion model to calculate the convection-diffusion engineering of soluble substances and suspended substances in water, as shown in formula (5):

[0052] ,

[0053] (5)

[0054] in, is the concentration of the substance, is the diffusion time, is the average flow velocity of the river, is the spatial coordinate, is the convective diffusion coefficient, is the first-order attenuation coefficient of the substance, and is the empirical parameter of the convection diffusion coefficient;

[0055] Step D14: construct a real-time control module, wherein the real-time control module is used to control the scheduling operations of gates and pump stations in the drainage system and change the scheduling rules by setting measurement parameters to achieve water flow measurement.

[0056] In the aforementioned urban water pollutant balance calculation method, the specific calibration and verification process of step D2 is shown in formula (6):

[0057] ,

[0058] ,

[0059] ; (6)

[0060] in, is the number of simulated data, For the Measured values, is the average value of the measured values, For the analog values, is the average value of the simulation values.

[0061] The aforementioned method for calculating the balance of urban water pollutants, step E, uses the overall balance calculation results of regional water pollutants and the verified pipe network-outlet-river integrated numerical model to perform spatiotemporal quantitative calculation of the balance of urban production and drainage pollutants and obtain the quantitative measurement results of the urban water pollutant balance, thereby completing the urban water pollutant balance calculation operation. Specifically, the obtained overall balance calculation results of regional water pollutants are produced into a time series on a daily scale and used as the input variable of the verified pipe network-outlet-river integrated numerical model, and then the verified pipe network-outlet-river integrated numerical model is used to reproduce the urban production and drainage pollutant balance calculation process as a whole and decompose it in time and space, and obtain the spatiotemporal quantitative measurement results of the pollution production and discharge process under the urban water use-drainage process, thereby obtaining the quantitative measurement results of the urban water pollutant balance.

[0062] An urban water pollutant balance measurement system includes a database construction module, an overall balance measurement module, a multi-factor monitoring module, a numerical model establishment module, and a spatiotemporal quantitative measurement module. The database construction module is used to construct a basic database of water pollutants in a target city.

[0063] The overall balance calculation module is used to calculate the sewage generation volume of each industry and the direct sewage discharge volume of each plot based on the basic database of water pollutants using the pollution reduction coefficient method and the proportional coefficient method, and use the chemical mass and water balance equation to calculate the equivalent sewage treatment volume, and then use the triangle graphic method to split the flow curve to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation results of regional water pollutants;

[0064] The multi-factor monitoring module is used to conduct in-situ control experiments on the drainage system and establish a pipeline-river multi-factor monitoring system for monitoring, thereby obtaining monitoring data. Based on the monitoring data, the response relationship between the river water level and the pipe network liquid level is quantitatively analyzed and the topological relationship between the pipe network and the river is corrected.

[0065] The numerical model building module is used to construct a drainage system pipe network-outlet-river channel integrated numerical model using the revised topological relationship between the pipe network and the river channel, and then use the monitoring data to calibrate and verify the model parameters of the pipe network-outlet-river channel integrated numerical model to obtain a verified pipe network-outlet-river channel integrated numerical model;

[0066] The spatiotemporal quantitative measurement module is used to perform spatiotemporal quantitative measurement of the balance of urban water pollutants produced and discharged using the overall balance measurement results of regional water pollutants and the verified pipe network-outlet-river integrated numerical model and obtain the quantitative measurement results of the urban water pollutant balance, thereby completing the urban water pollutant balance measurement operation.

[0067] The beneficial effects of the present invention are as follows: a method and system for calculating the balance of urban water pollutants of the present invention first constructs a basic database of water pollutants in a target city, then uses the pollution coefficient method and the proportional coefficient method based on the basic database of water pollutants to respectively calculate the sewage generation amount of each industry and the direct discharge amount of sewage from the plot, and uses the chemical mass and water balance equation to calculate the equivalent sewage treatment amount, and then uses the triangle graphic method to divide the flow curve to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation result of regional water pollutants, and then conducts an in-situ control experiment on the drainage system and establishes a pipeline-river multi-factor monitoring system for monitoring, thereby obtaining monitoring data, and then quantitatively analyzes the response relationship between the changes in the river water level and the pipe network liquid level based on the monitoring data and corrects the topological relationship between the pipe network and the river, and then uses the corrected topological relationship between the pipe network and the river to construct a drainage system pipe network-outlet-river integrated numerical model, and then uses the monitoring data to calibrate and verify the model parameters of the pipe network-outlet-river integrated numerical model and obtain the verified pipe network-outlet-river integrated numerical model, and finally uses the regional The overall balance calculation results of water pollutants in the domain and the verified integrated numerical model of the pipe network, outlet, and river channel are used to quantitatively calculate the balance of urban water pollutants in spatiotemporal space and obtain the quantitative measurement results of the urban water pollutant balance, thus completing the urban water pollutant balance calculation operation; the water pollutant balance calculation method and system effectively realize the function of integrating the triangle diagram method, in-situ observation method, and numerical model method to accurately calculate the water pollutant balance of the urban drainage system. In addition, through in-situ control experiments on the drainage system and the pipe-river channel multi-factor monitoring system, the pipe network topology structure can be timely corrected and the pipe network-river channel hydrodynamic values ​​can be calibrated and verified. This not only avoids model debugging distortion caused by pipe network structure errors, but also better reflects the dynamic evolution process of water pollutants. This provides a new method for accurately and quantitatively measuring the spatiotemporal changes of urban water pollution loads under changing scenarios, and is of great significance for guiding the precise prevention and control of urban water pollution and targeted water environment governance. It makes up for the shortcomings of traditional methods in the insufficient accuracy of spatiotemporal dynamic measurement of urban water pollutants in the context of rapid urbanization, and significantly improves the reliability of pollution source tracing in complex urban water systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is an overall flow chart of a method for calculating the balance of urban water pollutants of the present invention;

[0069] Figure 2 It is a schematic diagram of the urban water collection zoning and pipe network-outlet-river system of the present invention. DETAILED DESCRIPTION

[0070] The present invention will be further described below with reference to the accompanying drawings.

[0071] like Figure 1As shown, a method for calculating the balance of urban water pollutants of the present invention comprises the following steps:

[0072] Step A: constructing a basic database of water pollutants in a target city, the basic database of water pollutants including static data and dynamic data. The static data includes population size data, land use area data, pipe network vector data, river vector data, outlet data, and pump station data of the target city. The dynamic data includes urban residential tap water sales volume, industrial and service water sales volume, special industry water sales volume, daily rainfall, sewage online monitoring data of enterprises with online monitoring, water use and discharge data of enterprises without online monitoring, sewage treatment volume of urban sewage treatment plants, and COD concentration of sewage treatment plant influent. The urban residential tap water sales volume includes residential water sales volume, non-residential water sales volume, secondary water supply sales volume, and special poverty preferential water sales volume.

[0073] The specific construction process of the water pollutant basic database is to decompose the dynamic data according to the water supply division of the water plant and the drainage division of the sewage treatment plant and in combination with the population size data and land use area data of each administrative unit of the target city.

[0074] Step B, based on the basic database of water pollutants, the pollution reduction coefficient method and the proportional coefficient method are used to calculate the sewage generation volume of each industry and the direct discharge volume of sewage from the plot, and the chemical mass and water balance equation is used to calculate the equivalent sewage treatment volume, and then the triangle graphic method is used to divide the flow curve to calculate the amount of external water entering the pipe network, so as to perform an overall balance calculation of regional water pollutants and obtain the overall balance calculation results of regional water pollutants, wherein the overall balance calculation results of regional water pollutants include sewage generation volume, sewage treatment volume, direct discharge volume of sewage and the amount of external water entering the pipe network. The specific steps are as follows,

[0075] Step B1, using the pollution reduction coefficient method to calculate the amount of wastewater generated by each industry, where the amount of wastewater generated is equal to the product of water consumption and the corresponding pollution reduction coefficient;

[0076] Step B2, using the proportional coefficient method to calculate the direct discharge volume of sewage from each industry plot, wherein the direct discharge volume of sewage from the plot is specifically calculated using the product volume of the plot and the direct discharge coefficient estimated based on the pipe network;

[0077] Step B3, use the chemical mass and water balance equation to calculate the equivalent sewage treatment capacity. Specifically, the chemical mass and water balance relationship of the drainage system water quality characteristic factor is used to calculate the equivalent sewage treatment capacity of the urban sewage treatment plant. The chemical oxygen demand (COD) is used instead of water volume as the calculation factor and the chemical mass and water balance equation is used for calculation. The calculation process is shown in formula (1).

[0078] ,

[0079] (1)

[0080] in, is the total sewage inflow flow of the sewage treatment plant under dry flow conditions, is the amount of raw sewage, is the inflow and infiltration of external water, including groundwater and surface water, 、 and They are the concentrations of water quality characteristic factors of total sewage, primary sewage and external water under dry flow conditions;

[0081] Step B4, using the triangle graphical method to segment the flow curve to calculate the amount of external water entering the pipe network, specifically, the flow curve of the sewage pipe network outlet in the corresponding time period is segmented according to the chemical mass and water balance equation, and then the daily flow values ​​in the selected time period at the end of the sewage pipe network are arranged in ascending order to form an S-shaped curve.

[0082] Step C: Conduct an in-situ control experiment on the drainage system and establish a pipeline-river multi-factor monitoring system to monitor the system, thereby obtaining monitoring data. Then, based on the monitoring data, quantitatively analyze the response relationship between the changes in the river water level and the pipe network liquid level and correct the topological relationship between the pipe network and the river. The specific steps are as follows:

[0083] Step C1: Conduct an in-situ control experiment on the drainage system. Specifically, the river water level and the pipe network liquid level are regulated separately using the control variable method. The specific steps are as follows:

[0084] Step C11, river water level control, specifically, first starting the river pumping station to lower the river water level, then adjusting the pumping station discharge flow to maintain the river water level, then shutting down the pumping station and monitoring the slow rise of the water level, then opening the water supply gate and monitoring the significant rise of the river water level, then increasing the gate opening and monitoring the accelerated rise of the water level;

[0085] Step C12, controlling the sewage lift pumping station in the pipeline, specifically shutting down one sewage lift pumping station first, then shutting down another sewage lift pumping station, then shutting down another sewage lift pumping station, and finally shutting down all integrated pumping stations, while simultaneously monitoring the pipeline liquid level changes;

[0086] Step C13, airbag blocking control, specifically uses airbags to block the sewage interception pipes on both sides of the river channel and determines the blocking points according to the actual situation. The pipeline is then divided into two independent pipelines and the changes in the pipeline liquid levels in the two sections are monitored separately when the river water level control is superimposed;

[0087] Step C14, pipe branch control, specifically using air bags to block multiple connected pipelines, then controlling different branch ports in the pipe sections and separately monitoring the changes in liquid levels in different pipe sections;

[0088] Step C2: Establish a pipeline-river multi-factor monitoring system for monitoring. The pipeline-river multi-factor monitoring system specifically monitors the pipeline liquid level, river water level, diversion outlet flow, and video during the drainage system in-situ control experiment. The specific steps are as follows:

[0089] Step C21: Monitoring the pipeline liquid level and river water level. Specifically, each target pipeline is monitored using a pipeline liquid level gauge, and each target river is monitored upstream and downstream using a river float level gauge. The river water level near the sewage well is also monitored simultaneously.

[0090] Step C22: monitoring the flow rate at the pipeline junction, specifically installing a fixed flow meter on site when encountering a pipe network bifurcation;

[0091] Step C23: Pipeline video monitoring, using a closed-circuit television monitoring system to endoscopically detect abnormal pipeline seepage.

[0092] like Figure 2 As shown, in step D, the topological relationship between the corrected pipe network and the river channel is used to construct a drainage system pipe network-outlet-river channel integrated numerical model, and then the monitoring data is used to calibrate and verify the model parameters of the pipe network-outlet-river channel integrated numerical model to obtain the verified pipe network-outlet-river channel integrated numerical model. The specific steps are as follows:

[0093] Step D1, constructing a drainage system pipe network-outlet-river integrated numerical model using the revised topological relationship between the pipe network and the river, wherein the pipe network-outlet-river integrated numerical model includes a rainfall runoff module, a pipe flow calculation module, a water quality module, and a real-time control module;

[0094] Step D2, using monitoring data to calibrate and verify the model parameters of the pipeline-outlet-river channel integrated numerical model and obtain the verified pipeline-outlet-river channel integrated numerical model, wherein the calibration and verification indicators use the Nash efficiency coefficient NSE, the deviation percentage PBIAS and the ratio coefficient RSR of the root mean square error to the observation standard deviation, the Nash efficiency coefficient NSE is used to quantify the measurement accuracy of the pipeline-outlet-river channel integrated numerical model by using the relative size of the residual variance and the measurement data variance, the deviation percentage PBIAS is used to measure the average trend of the data deviating from the observed data, and the ratio coefficient RSR of the root mean square error to the observation standard deviation is used to standardize the root mean square error by using the standard deviation of the observed value.

[0095] The specific steps of step D1 are as follows:

[0096] Step D11: constructing a rainfall runoff module, wherein the rainfall runoff module adopts the Horton infiltration formula, as shown in formula (2):

[0097] (2)

[0098] in, is the infiltration rate, To stabilize the infiltration rate, is the initial infiltration rate, For rainfall time, is the decay constant;

[0099] Step D12: construct a pipe flow calculation module, wherein the pipe flow calculation module adopts the Saint-Venant equations of open channel unsteady flow partial differential equations. The specific steps are as follows:

[0100] Step D121, establish the mass conservation equation and momentum conservation equation, as shown in formula (3),

[0101] ,

[0102] (3);

[0103] in, For traffic, is the cross-sectional area, is the acceleration due to gravity, is the horizontal angle, is the bed slope, is the delivery volume;

[0104] In step D122, the steady flow of the river is calculated using the Manning formula, as shown in formula (4):

[0105] (4)

[0106] in, is the roughness, is the hydraulic radius, It is the bottom slope of the river channel;

[0107] Step D13: constructing a water quality module, wherein the water quality module uses a one-dimensional convection-diffusion model to calculate the convection-diffusion engineering of soluble substances and suspended substances in water, as shown in formula (5):

[0108] ,

[0109] (5)

[0110] in, is the concentration of the substance, is the diffusion time, is the average flow velocity of the river, is the spatial coordinate, is the convective diffusion coefficient, is the first-order attenuation coefficient of the substance, and is the empirical parameter of the convection diffusion coefficient;

[0111] Step D14: construct a real-time control module, wherein the real-time control module is used to control the scheduling operations of gates and pump stations in the drainage system and change the scheduling rules by setting measurement parameters to achieve water flow measurement.

[0112] The specific calibration and verification process of step D2 is shown in formula (6).

[0113] ,

[0114] ,

[0115] ; (6)

[0116] in, is the number of simulated data, For the Measured values, is the average value of the measured values, For the analog values, is the average value of the simulation values.

[0117] Step E, using the overall balance calculation results of regional water pollutants and the verified pipe network-outlet-river integrated numerical model to conduct spatiotemporal quantitative calculation of the balance of urban production and drainage pollutants and obtain the quantitative calculation results of urban water pollutant balance, thereby completing the urban water pollutant balance calculation operation. Specifically, the obtained overall balance calculation results of regional water pollutants are made into a time series on a daily scale and used as the input variable of the verified pipe network-outlet-river integrated numerical model, and then the verified pipe network-outlet-river integrated numerical model is used to reproduce the urban production and drainage pollutant balance calculation process as a whole and decompose it in time and space, and obtain the spatiotemporal quantitative calculation results of the pollution production and discharge process under the urban water use-drainage process, thereby obtaining the quantitative calculation results of the urban water pollutant balance.

[0118] An urban water pollutant balance measurement system includes a database construction module, an overall balance measurement module, a multi-factor monitoring module, a numerical model establishment module, and a spatiotemporal quantitative measurement module. The database construction module is used to construct a basic database of water pollutants in a target city.

[0119] The overall balance calculation module is used to calculate the sewage generation volume of each industry and the direct sewage discharge volume of each plot based on the basic database of water pollutants using the pollution reduction coefficient method and the proportional coefficient method, and use the chemical mass and water balance equation to calculate the equivalent sewage treatment volume, and then use the triangle graphic method to split the flow curve to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation results of regional water pollutants;

[0120] The multi-factor monitoring module is used to conduct in-situ control experiments on the drainage system and establish a pipeline-river multi-factor monitoring system for monitoring, thereby obtaining monitoring data. Based on the monitoring data, the response relationship between the river water level and the pipe network liquid level is quantitatively analyzed and the topological relationship between the pipe network and the river is corrected.

[0121] The numerical model building module is used to construct a drainage system pipe network-outlet-river channel integrated numerical model using the revised topological relationship between the pipe network and the river channel, and then use the monitoring data to calibrate and verify the model parameters of the pipe network-outlet-river channel integrated numerical model to obtain a verified pipe network-outlet-river channel integrated numerical model;

[0122] The spatiotemporal quantitative measurement module is used to perform spatiotemporal quantitative measurement of the balance of urban water pollutants produced and discharged using the overall balance measurement results of regional water pollutants and the verified pipe network-outlet-river integrated numerical model and obtain the quantitative measurement results of the urban water pollutant balance, thereby completing the urban water pollutant balance measurement operation.

[0123] In summary, a method and system for calculating the balance of urban water pollutants of the present invention first constructs a basic database of water pollutants in the target city, and then uses the pollution coefficient method and the proportional coefficient method based on the basic database of water pollutants to calculate the sewage generation of each industry and the direct discharge of sewage from the plot, and uses the chemical mass and water balance equation to calculate the equivalent sewage treatment volume, and then uses the triangle graphic method to split the flow curve to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation results of regional water pollutants, and then conducting in-situ control experiments on the drainage system and establishing a pipeline-river multi-factor monitoring system for monitoring, thereby obtaining monitoring data, and then quantitatively analyzing the response relationship between the changes in the river water level and the pipe network liquid level based on the monitoring data and correcting the topological relationship between the pipe network and the river, and then using the corrected topological relationship between the pipe network and the river to construct a drainage system pipe network-outlet-river integrated numerical model, and then using the monitoring data to calibrate and verify the model parameters of the pipe network-outlet-river integrated numerical model and obtain the verified model parameters. An integrated numerical model of pipe network-outlet-river channel is constructed, and finally the regional water pollutant overall balance measurement results and the verified integrated numerical model of pipe network-outlet-river channel are used to quantitatively measure the spatiotemporal balance of urban water production and drainage pollutants and obtain the quantitative measurement results of urban water pollutant balance, thereby completing the urban water pollutant balance measurement operation; the present invention effectively realizes the function of accurately measuring the water pollutant balance of urban drainage system with integrated triangle diagram method, in-situ observation method and numerical model method, and through in-situ control experiments on the drainage system and the pipe-river channel multi-factor monitoring system, the pipe network topology structure can be timely corrected and the pipe network-river channel hydrodynamic values ​​can be calibrated and verified, which not only avoids the model debugging distortion caused by pipe network structure errors, but also better reflects the dynamic evolution process of water pollutants. This provides a new method for accurately quantitatively measuring the spatiotemporal changes of urban water pollution load under changing scenarios, and is of great significance for guiding the precise prevention and control of urban water pollution and targeted governance of water environment, and significantly improves the reliability of pollution tracing under complex urban water systems.

[0124] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the balance of urban water pollutants, characterized by: The following steps are included: Step A: construct a basic database of water pollutants in target cities; Step B: Based on the basic water pollutant database, the pollution reduction coefficient method and the proportional coefficient method are used to calculate the wastewater generation volume of each industry and the direct wastewater discharge volume of the plot, and the chemical mass and water volume balance equation is used to calculate the equivalent wastewater treatment volume. The flow curve is then segmented using the triangle diagram method to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation results of regional water pollutants; Step C: Conducting in-situ control experiments on the drainage system and establishing a pipeline-river multi-factor monitoring system to monitor the system, thereby obtaining monitoring data. Based on the monitoring data, quantitative analysis is then performed to determine the relationship between the changes in the river water level and the pipe network level, and the topological relationship between the pipe network and the river is corrected. Step D: Use the revised topological relationship between the pipe network and the river to construct a drainage system pipe network-outlet-river integrated numerical model, and then use the monitoring data to calibrate and verify the model parameters of the pipe network-outlet-river integrated numerical model to obtain the verified pipe network-outlet-river integrated numerical model. The specific steps are as follows: Step D1: Use the corrected topological relationship between the pipe network and the river to construct a drainage system pipe network-outlet-river integrated numerical model, wherein the pipe network-outlet-river integrated numerical model includes a rainfall runoff module, a pipe flow calculation module, a water quality module, and a real-time control module. The specific steps are as follows: Step D11: constructing a rainfall runoff module, wherein the rainfall runoff module adopts Horton's infiltration formula, as shown in formula (2): Among them, f m is the infiltration rate, f c To stabilize the infiltration rate, f0 is the initial infiltration rate, t1 is the rainfall time, and k0 is the decay constant; Step D12: construct a pipe flow calculation module, wherein the pipe flow calculation module adopts the Saint-Venant equations of open channel unsteady flow partial differential equations. The specific steps are as follows: Step D121: Establish the mass conservation equation and momentum conservation equation, as shown in formula (3). Where Q is the flow rate, A is the cross-sectional area, g is the acceleration of gravity, θ is the horizontal angle, S0 is the bed slope, and K is the transport capacity; In step D122, the steady flow of the river is calculated using the Manning formula, as shown in formula (4): Among them, n1 is the roughness, R is the hydraulic radius, and e is the river bottom slope; Step D13: constructing a water quality module, wherein the water quality module uses a one-dimensional convection-diffusion model to calculate the convection-diffusion engineering of soluble substances and suspended substances in water, as shown in formula (5): E x =aV b (5) Where c is the concentration of the substance, t2 is the diffusion time, V is the average flow velocity of the river, x is the spatial coordinate, E x is the convective diffusion coefficient, k c is the first-order attenuation coefficient of the substance, a and b are the empirical parameters of the convection diffusion coefficient; Step D14: constructing a real-time control module, wherein the real-time control module is used to control the scheduling operation of gates and pump stations in the drainage system and change the scheduling rules by setting measurement parameters to achieve water flow measurement; Step D2, using the monitoring data to calibrate and verify the model parameters of the pipeline network-outlet-river channel integrated numerical model and obtain the verified pipeline network-outlet-river channel integrated numerical model, wherein the calibration and verification indicators use the Nash efficiency coefficient NSE, the deviation percentage PBIAS and the ratio coefficient of the root mean square error to the observation standard deviation RSR. The Nash efficiency coefficient NSE is used to quantify the measurement accuracy of the pipeline network-outlet-river channel integrated numerical model by using the relative size of the residual variance and the measurement data variance. The deviation percentage PBIAS is used to measure the average trend of data deviation from the observation data. The ratio coefficient RSR of the root mean square error to the observation standard deviation is used to standardize the root mean square error by using the standard deviation of the observation value. The specific calibration and verification process is shown in formula (6). Among them, n2 is the number of simulated data, Q si is the ith measured value, is the average value of the measured values, Q mi is the ith simulation value, is the average value of the simulation value; Step E: Use the overall balance calculation results of regional water pollutants and the verified integrated numerical model of pipe network, outlet and river to quantitatively calculate the balance of urban water pollutants in time and space and obtain the quantitative calculation results of urban water pollutant balance, thereby completing the urban water pollutant balance calculation operation.

2. The method for calculating the balance of urban water pollutants according to claim 1, characterized in that: Step A: constructing a basic database of water pollutants in a target city, the basic database of water pollutants including static data and dynamic data. The static data includes population size data, land use area data, pipe network vector data, river vector data, outlet data, and pump station data of the target city. The dynamic data includes urban residential tap water sales volume, industrial and service water sales volume, special industry water sales volume, daily rainfall, sewage online monitoring data of enterprises with online monitoring, water use and discharge data of enterprises without online monitoring, sewage treatment volume of urban sewage treatment plants, and COD concentration of sewage treatment plant influent. The urban residential tap water sales volume includes residential water sales volume, non-residential water sales volume, secondary water supply sales volume, and special poverty preferential water sales volume. The specific construction process of the water pollutant basic database is to decompose the dynamic data according to the water supply division of the water plant and the drainage division of the sewage treatment plant and in combination with the population size data and land use area data of each administrative unit of the target city.

3. The method for calculating the balance of urban water pollutants according to claim 2, characterized in that: Step B, based on the basic database of water pollutants, the pollution reduction coefficient method and the proportional coefficient method are used to calculate the sewage generation volume of each industry and the direct discharge volume of sewage from the plot, and the chemical mass and water balance equation is used to calculate the equivalent sewage treatment volume, and then the triangle graphic method is used to divide the flow curve to calculate the amount of external water entering the pipe network, so as to perform an overall balance calculation of regional water pollutants and obtain the overall balance calculation results of regional water pollutants, wherein the overall balance calculation results of regional water pollutants include sewage generation volume, sewage treatment volume, direct discharge volume of sewage and the amount of external water entering the pipe network. The specific steps are as follows, Step B1, using the pollution reduction coefficient method to calculate the amount of wastewater generated by each industry, where the amount of wastewater generated is equal to the product of water consumption and the corresponding pollution reduction coefficient; Step B2, using the proportional coefficient method to calculate the direct discharge volume of sewage from each industry plot, wherein the direct discharge volume of sewage from the plot is specifically calculated using the product volume of the plot and the direct discharge coefficient estimated based on the pipe network; Step B3, using the chemical mass and water balance equation to calculate the equivalent sewage treatment capacity, specifically using the chemical mass and water balance relationship of the drainage system water quality characteristic factor to calculate the equivalent sewage treatment capacity of the urban sewage treatment plant, using chemical oxygen demand COD instead of water volume as a calculation factor and using the chemical mass and water balance equation to calculate the calculation process as shown in formula (1), Q DWF C DWF =Q FS C FS +Q EW C EW , Q DWF =Q FS +Q EW (1) Among them, Q DWF is the total sewage inflow flow rate of the sewage treatment plant under dry flow conditions, Q FS is the amount of raw sewage, Q EW is the inflow and infiltration of external water including groundwater and surface water, C DWF 、C FS and C EW They are the concentrations of water quality characteristic factors of total sewage, primary sewage and external water under dry flow conditions; Step B4, using the triangle graphical method to segment the flow curve to calculate the amount of external water entering the pipe network, specifically, the flow curve of the sewage pipe network outlet in the corresponding time period is segmented according to the chemical mass and water balance equation, and then the daily flow values ​​in the selected time period at the end of the sewage pipe network are arranged in ascending order to form an S-shaped curve.

4. The method for calculating the urban water pollutant balance according to claim 3, characterized in that: Step C: Conduct an in-situ control experiment on the drainage system and establish a pipeline-river multi-factor monitoring system to monitor the system, thereby obtaining monitoring data. Then, based on the monitoring data, quantitatively analyze the response relationship between the changes in the river water level and the pipe network liquid level and correct the topological relationship between the pipe network and the river. The specific steps are as follows: Step C1: Conduct an in-situ control experiment on the drainage system. Specifically, the river water level and the pipe network liquid level are regulated separately using the control variable method. The specific steps are as follows: Step C11, river water level control, specifically, first starting the river pumping station to lower the river water level, then adjusting the pumping station discharge flow to maintain the river water level, then shutting down the pumping station and monitoring the slow rise of the water level, then opening the water supply gate and monitoring the significant rise of the river water level, then increasing the gate opening and monitoring the accelerated rise of the water level; Step C12, controlling the sewage lift pumping station in the pipeline, specifically shutting down one sewage lift pumping station first, then shutting down another sewage lift pumping station, then shutting down another sewage lift pumping station, and finally shutting down all integrated pumping stations, while simultaneously monitoring the pipeline liquid level changes; Step C13, airbag blocking control, specifically uses airbags to block the sewage interception pipes on both sides of the river channel and determines the blocking points according to the actual situation. The pipeline is then divided into two independent pipelines and the changes in the pipeline liquid levels in the two sections are monitored separately when the river water level control is superimposed; Step C14, pipe branch control, specifically using air bags to block multiple connected pipelines, then controlling different branch ports in the pipe sections and separately monitoring the changes in liquid levels in different pipe sections; Step C2: Establish a pipeline-river multi-factor monitoring system for monitoring. The pipeline-river multi-factor monitoring system specifically monitors the pipeline liquid level, river water level, diversion outlet flow, and video during the drainage system in-situ control experiment. The specific steps are as follows: Step C21: Monitoring the pipeline liquid level and river water level. Specifically, each target pipeline is monitored using a pipeline liquid level gauge, and each target river is monitored upstream and downstream using a river float level gauge. The river water level near the sewage well is also monitored simultaneously. Step C22: monitoring the flow rate at the pipeline junction, specifically installing a fixed flow meter on site when encountering a pipe network bifurcation; Step C23: Pipeline video monitoring, using a closed-circuit television monitoring system to endoscopically detect abnormal pipeline seepage.

5. The method for calculating the balance of urban water pollutants according to claim 1, characterized in that: Step E, using the overall balance calculation results of regional water pollutants and the verified pipe network-outlet-river integrated numerical model to conduct spatiotemporal quantitative calculation of the balance of urban production and drainage pollutants and obtain the quantitative calculation results of urban water pollutant balance, thereby completing the urban water pollutant balance calculation operation. Specifically, the obtained overall balance calculation results of regional water pollutants are made into a time series on a daily scale and used as the input variable of the verified pipe network-outlet-river integrated numerical model, and then the verified pipe network-outlet-river integrated numerical model is used to reproduce the urban production and drainage pollutant balance calculation process as a whole and decompose it in time and space, and obtain the spatiotemporal quantitative calculation results of the pollution production and discharge process under the urban water use-drainage process, thereby obtaining the quantitative calculation results of the urban water pollutant balance.

6. A system for calculating the balance of urban water pollutants, wherein the specific calculation process of the system is based on the method for calculating the balance of urban water pollutants according to any one of claims 1 to 5, and is characterized by: It includes a database construction module, an overall balance measurement module, a multi-factor monitoring module, a numerical model establishment module and a spatiotemporal quantitative measurement module. The database construction module is used to construct a basic database of water pollutants in target cities; The overall balance calculation module is used to calculate the sewage generation volume of each industry and the direct sewage discharge volume of each plot based on the basic database of water pollutants using the pollution reduction coefficient method and the proportional coefficient method, and use the chemical mass and water balance equation to calculate the equivalent sewage treatment volume, and then use the triangle graphic method to split the flow curve to calculate the amount of external water entering the pipe network, thereby performing an overall balance calculation of regional water pollutants and obtaining the overall balance calculation results of regional water pollutants; The multi-factor monitoring module is used to conduct in-situ control experiments on the drainage system and establish a pipeline-river multi-factor monitoring system for monitoring, thereby obtaining monitoring data. Based on the monitoring data, the response relationship between the river water level and the pipe network liquid level is quantitatively analyzed and the topological relationship between the pipe network and the river is corrected. The numerical model building module is used to construct a drainage system pipe network-outlet-river channel integrated numerical model using the revised topological relationship between the pipe network and the river channel, and then use the monitoring data to calibrate and verify the model parameters of the pipe network-outlet-river channel integrated numerical model to obtain a verified pipe network-outlet-river channel integrated numerical model; The spatiotemporal quantitative calculation module is used to perform spatiotemporal quantitative calculation of the balance of urban water pollutants produced and discharged using the overall balance calculation results of regional water pollutants and the verified pipe network-outlet-river integrated numerical model, and obtain the quantitative calculation results of the urban water pollutant balance, thereby completing the urban water pollutant balance calculation operation; The integrated numerical model of pipe network, outlet and river channel in the numerical model building module includes a rainfall runoff module, a pipe flow calculation module, a water quality module and a real-time control module; The calibration and verification indicators in the numerical model establishment module use the Nash efficiency coefficient NSE, the deviation percentage PBIAS and the ratio coefficient RSR of the root mean square error to the observation standard deviation. The Nash efficiency coefficient NSE is used to quantify the measurement accuracy of the integrated numerical model of the pipeline network, outlet and river channel by using the relative size of the residual variance and the measurement data variance. The deviation percentage PBIAS is used to measure the average trend of data deviation from the observed data. The ratio coefficient RSR of the root mean square error to the observation standard deviation is used to standardize the root mean square error by using the standard deviation of the observed value.

Images