Multi-objective design method and apparatus for runoff and pollution-based rainwater detention tanks

Abstract

The application discloses a kind of based on runoff and pollution rainwater storage tank multi-objective design method and equipment, it is related to urban drainage technical field.The method includes obtaining the rainfall parameter of target area, area parameter and pollutant parameter;Based on rainfall parameter, determine the rainfall of each period of target area;Utilize the preset mixed nonlinear runoff model and based on the rainfall of each period of target area and area parameter, determine the total runoff of each period of target area;Based on the total runoff of each period of target area and pollutant parameter, determine the pollution load of each period of target area;Based on the total runoff of each period of target area and pollution load, and with the goal of reducing peak flow, controlling non-point source pollution or water quality and quantity balance control, determine the target parameter of rainwater storage tank corresponding to target area.The calculation precision of rainwater storage tank key parameter is improved, and the dependence on data is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of urban drainage, and particularly relates to a rainwater storage tank multi-objective design method and equipment based on runoff and pollution. BACKGROUND

[0002] As one of the infrastructures for grey rainwater treatment in low impact development (LID), the rainwater storage tank plays an important role in runoff pollution regulation, runoff water storage, and flood peak flow reduction. The calculation methods of the key parameters of the rainwater storage tank mainly include two categories: a simplified empirical formula calculation method and a rainwater flood model calculation method.

[0003] The simplified empirical formula calculation method directly calculates the key parameters of the rainwater storage tank through an empirical formula. The current simplified empirical formula calculation method does not clearly limit the optimization target in the calculation process, and most of the simplified empirical formulas use empirical parameters. These empirical parameters mostly have thresholds, and the final calculation results will be greatly biased due to the selection of different parameters. Therefore, the calculation accuracy of the simplified empirical formula calculation method is low.

[0004] The rainwater flood model calculation method mainly calculates the key parameters of the rainwater storage tank through a runoff model, a pipe network model, and a water quality calculation module. However, the runoff model only simply divides the underlying surface into a permeable area and an impermeable area for runoff calculation, which cannot well describe the nonlinear runoff characteristics in the hydrological phenomenon. In addition, when establishing the pipe network model and simulating the runoff and pollution load of the LID facility, a large amount of data required for modeling needs to be input, so this method has a high dependence on data. SUMMARY

[0005] The main purpose of the present application is to provide a rainwater storage tank multi-objective design method and equipment based on runoff and pollution, so as to improve the calculation accuracy of the key parameters of the rainwater storage tank and reduce the dependence on data.

[0006] To achieve the above purpose, the present application provides a rainwater storage tank multi-objective design method based on runoff and pollution, comprising:

[0007] obtaining rainfall parameters, regional parameters, and pollutant parameters of a target region;

[0008] determining the rainfall of each period of the target region based on the rainfall parameters;

[0009] Using a pre-defined hybrid nonlinear runoff generation model and based on the rainfall in the target area at different time periods and the regional parameters, the total runoff in the target area at different time periods is determined; wherein, the pre-defined hybrid nonlinear runoff generation model includes multiple network branches, and different network branches are used to calculate the runoff in different types of sub-regions in the target area, and the types of sub-regions include at least bioretention facilities and permeable pavement;

[0010] The pollution load of the target area for each time period is determined based on the total runoff of the target area for each time period and the pollutant parameters;

[0011] Based on the total runoff and pollution load of the target area at each time period, the target parameters of the corresponding rainwater storage tank in the target area are determined with the aim of reducing peak flow, controlling non-point source pollution, or achieving water quality and quantity balance control.

[0012] Optionally, the types of sub-regions may also include bare soil areas, vegetation-covered areas, impermeable roofs, green roofs, and impermeable roads, and the regional parameters include sub-region parameters for each type of sub-region; the step of using a preset hybrid nonlinear runoff generation model and based on the rainfall in each time period of the target area and the regional parameters to determine the total runoff of the target area in each time period includes: for any time period, inputting each of the sub-region parameters and the rainfall into the corresponding network branch to obtain the runoff of each of the sub-regions in the time period, and determining the total runoff of the target area based on the runoff of each of the sub-regions.

[0013] Optionally, the sub-region parameters of the bioretention facility include at least the water level change at the surface of the reservoir, the height of the overflow weir, the inflow rate of the bioretention facility, and the outflow rate of the drainage pipe; the model formula for the network branch corresponding to the bioretention facility is:

[0014]

[0015] In the formula, The runoff of the sub-region of the bioretention facility; The runoff reduction factor for the bioretention facility; Let t be the change in water level at the surface of the water storage layer during time period t; The height of the overflow weir; The inflow rate of the bioretention facility during time period t; Let t be the outflow rate of the drainage pipe during time period t; The infiltration rate of the filter layer during time period t is the amount of water absorbed during that period.

[0016] Optionally, the sub-region parameters of the permeable pavement include at least water storage capacity and the proportion of the area of ​​the bare soil sub-region to the total area of ​​the target region; the model formula for the network branch corresponding to the permeable pavement is:

[0017]

[0018] wherein, is the runoff of the sub-area of the permeable pavement; is the rainfall of the time period t; is the runoff reduction coefficient of the permeable pavement; W(t) is the water storage of the sub-area of the permeable pavement at the time period t; is the proportion of the sub-area of the bare soil region to the total area of the target region; W p is the water storage capacity of the pavement layer of the permeable pavement.

[0019] Optionally, the pollutant parameter comprises an initial pollutant parameter and a mid-late pollutant parameter, and the determining of the pollution load of each time period of the target region based on the total runoff of each time period of the target region and the pollutant parameter comprises: obtaining an initial runoff parameter of the target region; dividing a rainfall event of the target region into an initial rainfall period and a mid-late rainfall period based on the initial runoff parameter; for any time period, if it is determined based on the runoff parameter of the time period that the time period is in the initial rainfall period, determining the pollution load of the time period based on the total runoff of the time period and the initial pollutant parameter; for any time period, if it is determined based on the runoff parameter of the time period that the time period is in the mid-late rainfall period, determining the pollution load of the time period based on the total runoff of the time period and the mid-late pollutant parameter.

[0020] Optionally, the determining of the target parameter of the rainwater storage tank corresponding to the target region based on the total runoff and the pollution load of each time period of the target region and taking the reduction of peak flow, the control of non-point source pollution or the water quality and quantity balance control as the target comprises: determining an inflow hydrograph based on the total runoff of each time period of the target region and determining a pollution load hydrograph based on the pollution load of each time period of the target region; determining the target parameter of the rainwater storage tank corresponding to the target region based on the inflow hydrograph and taking the reduction of peak flow as the target; or determining the target parameter of the rainwater storage tank corresponding to the target region based on the pollution load hydrograph and taking the control of non-point source pollution as the target; or determining the target parameter of the rainwater storage tank corresponding to the target region based on the inflow hydrograph and the pollution load hydrograph and taking the water quality and quantity balance control as the target.

[0021] Optionally, the determining of the target parameter of the rainwater storage tank corresponding to the target region based on the inflow hydrograph and taking the reduction of peak flow as the target comprises: taking a downstream design flow of the rainwater storage tank as a control standard and determining a first time and a second time based on the inflow hydrograph; determining a first effective volume based on the first time and the second time by using a preset first volume formula, and determining the target parameter of the rainwater storage tank corresponding to the target region based on the first effective volume.

[0022] Optionally, the determining the target parameter of the rainwater storage tank corresponding to the target region based on the pollution load hydrograph and aiming at controlling the non-point source pollution comprises: taking the pollution control rate of the rainwater storage tank as a control standard and determining a third time based on the pollution load hydrograph; determining a second effective volume based on the third time by using a preset second volume formula, and determining the target parameter of the rainwater storage tank corresponding to the target region based on the second effective volume.

[0023] Optionally, the determining the target parameter of the rainwater storage tank corresponding to the target region based on the inflow hydrograph and the pollution load hydrograph and aiming at water quality and water quantity balance control comprises: taking the peak flow reduction rate of the rainwater storage tank as a control standard and determining a first time and a second time based on the inflow hydrograph, and determining a first effective volume by using a preset first volume formula, the first time and the second time; taking the pollution control rate of the rainwater storage tank as a control standard and determining a third time based on the pollution load hydrograph, and determining a second effective volume by using a preset second volume formula, the third time; selecting a maximum value from the first effective volume and the second effective volume, and determining the target parameter of the rainwater storage tank corresponding to the target region based on the maximum value.

[0024] In addition, to achieve the above object, the present application also provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, and the processor implements the multi-objective design method of rainwater storage tank based on runoff and pollution as described above when executing the program.

[0025] The multi-objective design method of rainwater storage tank based on runoff and pollution of the present application can calculate the runoff of different types of sub-regions in the target region by using a preset mixed nonlinear runoff model, and then determine the total runoff of the target region based on the runoff of each type of sub-region, that is, the influence of the underlying surface type on runoff calculation is considered, thereby improving the accuracy of runoff calculation of the target region. Secondly, by considering runoff and pollution, the target parameter of the rainwater storage tank is calculated by taking peak flow reduction, non-point source pollution control or water quality and water quantity balance control as the control target, which not only clearly defines the control target, but also increases the number of control targets, thereby further improving the calculation accuracy of the target parameter of the rainwater storage tank. Finally, the multi-objective design method of rainwater storage tank of the present application can quickly calculate the target parameter of the rainwater storage tank without establishing a model and simulating LID facilities, thereby reducing the dependence on data. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1is one of flowcharts of a rainwater storage tank multi-objective design method of an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of a runoff model architecture of a non-linear time-varying process of an embodiment of the present application;

[0028] Figure 3 is another flowchart of a rainwater storage tank multi-objective design method of an embodiment of the present application;

[0029] Figure 4(a) is a schematic diagram of an inflow hydrograph of one specific embodiment of the present application;

[0030] Figure 4(b) is a schematic diagram of a pollution load hydrograph of one specific embodiment of the present application;

[0031] Figure 5 is a schematic diagram of an inflow hydrograph and downstream design flow of one specific embodiment of the present application;

[0032] Figure 6 is a schematic diagram of a pollution load hydrograph and pollution control rate of one specific embodiment of the present application;

[0033] Figure 7 is a schematic diagram of peak flow reduction rate and pollution control rate of one specific embodiment of the present application;

[0034] Figure 8 An example of a schematic diagram of a physical structure of an electronic device is shown in the figure;

[0035] In the figure, 810, processor; 820, communication interface; 830, memory; 840, communication bus.

[0036] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0038] As one of the infrastructures for grey water treatment in low impact development (LID), rainwater storage tanks play an important role in runoff pollution regulation, runoff water storage, and flood peak flow reduction. The calculation methods of the key parameters of rainwater storage tanks can be divided into two categories: simplified empirical formula calculation method and rainwater model calculation method.

[0039] Among them, the simplified empirical formula calculation method is mainly to directly calculate the key parameters of the rainwater storage tank through the empirical formula. At present, the existing simplified empirical formula calculation method for the volume of the storage tank has the triangular flow process line method, the storage indication method, the simple method, the detachment coefficient method and the like. These empirical formulas are all based on empirical parameters to directly calculate the key parameters of the rainwater storage tank, and thus have the following problems:

[0040] Firstly, the limitation of the control target in the calculation process of the simplified empirical formula calculation method is not clear. Although most of the existing simplified empirical formulas are calculated with the target of reducing the peak flow, the control target plays a small role in the empirical formula. The principle of these simplified empirical formulas is mostly to use the difference between the inflow process line and the outflow process line, and the obtained reduction is the total runoff reduction. For the target of reducing the peak flow, it will lead to overdesign of the volume and waste of resources.

[0041] Secondly, the empirical formula of the simplified empirical formula calculation method generally uses empirical parameters, and most of the empirical parameters have threshold values. If the selected empirical parameters are different, the final calculation results will also have a large deviation. For example, if the control of surface pollution is the target, the key to the design of the storage tank is the interception condition of the initial rainwater, and different countries have different interception standards, including runoff depth, rainfall time, rainfall and pollution load. For example, in the calculation formula of the storage tank with the target of controlling runoff pollution, the runoff depth or time is mostly quoted as a parameter, but due to the influence of multiple factors such as rainfall conditions and underlying surface types, the value is uncertain. Defining the initial rainwater by pollution load is the best for pollution control, but the water quality change is difficult to control, and even in the area with serious pollution, the whole runoff pollution is higher than the defined value.

[0042] Further, the rainwater model calculation method is mainly to calculate the key parameters of the rainwater storage tank through the runoff model, the pipe network model and the water quality calculation module. The rainwater model applies computer model and simulation technology, can quickly select, compare and evaluate the design scheme, and can effectively improve the reliability of the design and operation of the storage tank.

[0043] At present, the commonly used rain flood model is SWMM model. The SWMM model contains runoff model, pipe network model and water quality calculation module, and different calculation methods can be used according to the calculation accuracy requirement. However, in the runoff part, the SWMM model mainly uses the empirical formula based on infiltration, and the underlying surface type is simply divided into two types of permeable area and impervious area. This simple classification cannot well describe the nonlinear runoff characteristics in the hydrological phenomenon. Especially for the urban underlying surface with LID facilities, the nonlinear of urban hydrological process is more complex and significant; rainfall intensity, soil permeability, soil porosity, water conductivity and saturated soil moisture content will affect the response relationship of rainfall runoff to different permeable areas, thereby affecting the time-varying process of runoff.

[0044] In addition, when modeling and simulating the runoff and pollution load of LID facilities, these rain flood models need to input a large amount of various data to support the modeling and simulation process, such as urban topographic data, sewer network data, etc., so the data requirement and dependence are high, and the application of the actual engineering will be limited in the areas lacking of data. It should be noted that the area lacking of data refers to the area lacking of topographic data, sewer network data and other data.

[0045] Some scholars use the measured long sequence hydrological data of more than 60 basins in different climate regions around the world to analyze and obtain the inherent power function relationship of the earth hydrological system, and further put forward the corresponding time-varying gain model. At present, many scholars have improved it and developed a nonlinear time-varying gain model based on city (TVGM-urban), which divides the urban underlying surface into vegetation covered area, bare soil area, impervious roof, green roof and impervious underlying surface. Some researches compare TVGM-urban with Horton and SCSCN models, and show that TVGM-urban model can better describe the nonlinear runoff process of city, but for the runoff calculation of low impact development mode, the single green roof in TVGM-urban is obviously insufficient, so the model needs to be expanded with more LID facility calculation modules for use.

[0046] In summary, the simplified empirical formula calculation method has unclear limitation for regulation and optimization target, and the calculation accuracy is low; and the rain flood model calculation method only simply divides the underlying surface type into permeable area and impervious area in the runoff part, resulting in inaccurate runoff calculation, and the rain flood model calculation method has high dependence on data.

[0047] Based on this, the embodiment of the present application provides a runoff and pollution based rainwater storage tank multi-objective design method and equipment. The multi-objective design method of the embodiment of the present application is between the simplified empirical formula calculation method and the rainwater model calculation method. The multi-objective design method has multiple explicit control targets, and does not need to obtain a large amount of data to establish a model and simulate the runoff and pollution load of the LID facility. In addition, by using the preset mixed nonlinear runoff model, the types of urban underlying surfaces are divided in detail. Different calculation formulas are used to calculate the runoff for different types of sub-regions, so as to effectively improve the accuracy of runoff calculation for the target region, improve the calculation accuracy of the target parameters of the rainwater storage tank, and reduce the dependence on data.

[0048] Figure 1 is one of the flowcharts of the rainwater storage tank multi-objective design method of the embodiment of the present application. As shown in Figure 1 , the runoff and pollution based rainwater storage tank multi-objective design method can include the following steps:

[0049] Step 110: Obtain the rainfall parameters, regional parameters and pollutant parameters of the target region.

[0050] First of all, it should be pointed out that the target region described in the embodiment of the present application can be any catchment area that needs to set up a rainwater storage tank. For example, the target region can be a residential area, an industrial park, a traffic corridor, etc. in a city, or can be agricultural land, a riparian zone and a waterfront area, etc. In addition, the rainwater storage tank multi-objective design method of the embodiment of the present application is more suitable for designing a rainwater storage tank for a small range and a region lacking data, such as an old city lacking pipe network data, a town, a planned new area, etc.

[0051] In this embodiment, when a rainwater storage tank needs to be designed for a target region, the rainfall parameters, regional parameters and pollutant parameters of the target region can be obtained first. The rainfall parameters can include (but are not limited to): return period, total rainfall, rainfall duration, peak factor, calculation step, pre-impact rainfall, storm intensity formula parameter, spatial distribution characteristics, rainfall interval time, peak rainfall intensity, etc. These rainfall parameters can be directly obtained from the existing meteorological database, hydro-meteorological data center, etc. or can be derived from meteorological data of similar regions.

[0052] Further, the regional parameters refer to data related to the runoff process in the target region. It should be noted that the runoff process refers to the process of converting rainfall or other forms of water input (such as snowmelt, irrigation water, etc.) into runoff on the ground or underground. It can be seen that the runoff process is not only related to the climate conditions of the target region, but also related to the soil properties, topography, vegetation coverage, and other factors of the target region. Therefore, the regional parameters can include (but are not limited to): soil permeability, soil depth, soil moisture, saturated hydraulic conductivity, vegetation density, slope, elevation, and area of the target region, etc.

[0053] In the present embodiment, the regional parameters can be obtained from the existing geological database, vegetation coverage remote sensing image, hydrological system database, NASA Earthdata, etc.

[0054] Finally, the pollutant parameters of the target region can include the concentrations and sources of various pollutants in the target region, which can be obtained from the database of the environmental monitoring station.

[0055] It is worth mentioning that the pollutant parameters in the present embodiment mainly monitor TSS (Total Suspended Solids). Since the change of total suspended solids is closely related to the change of other pollutants, for example, many pollutants can be adsorbed on the total suspended solids or co-precipitate with the total suspended solids, if the total suspended solids decrease, it can be indicated that these pollutants are also decreasing. Therefore, the present embodiment takes the total suspended solids as the control target of pollution, obtains the reduction trend of the total suspended solids, and further obtains the reduction trend of other pollutants according to the correlation between the total suspended solids and other pollutants. Thus, the calculation can be simplified, the complex multivariate problem can be converted into a single variable problem, the complexity of calculation is reduced, and the reduction rate target of other typical pollutants can be evaluated.

[0056] Step 120: determining the rainfall of each period of the target region based on the rainfall parameters.

[0057] After obtaining the rainfall parameters, regional parameters, and pollutant parameters of the target region, the rainfall type of the target region and the rainfall of each period of the target region can be further determined according to the rainfall parameters, and the rainfall of each period can constitute a rainfall type curve.

[0058] It should be noted that the rain type refers to the time distribution, intensity change and spatial distribution characteristics of a rainfall event in a certain region within a specific time period, and the change curve of rainfall with time is the rain type curve. For example, if the rainfall intensity in a certain region is small at the beginning of the rainfall, but gradually increases with time until a maximum value is reached at a certain time point, and then gradually decreases, the rain type of this rainfall event in the region is unimodal, which is usually used to describe most typical storm events. Rain type also includes multi-peak type, uniform type, initial scouring type, etc.

[0059] In addition, the time period described in the embodiments of the present application can be in units of minutes, hours or specific time intervals, and the time period is not limited here.

[0060] In the present embodiment, the existing rain type model can be used to determine the rain type of the target region and the rainfall in each time period, for example, Chicago rain type, Pilgrim & Cordery rain type, Huff rain type, triangular rain type, etc. The present embodiment preferentially selects the Chicago rain type to determine the rainfall in each time period. Specifically, the rainfall parameters can be input into the Chicago rain type, and the Chicago rain type will output the rain type and the rainfall in each time period. A rain intensity map can also be drawn for analyzing the rain intensity distribution.

[0061] Step 130: determining the total runoff in each time period of the target region by using a preset mixed nonlinear runoff model and based on the rainfall in each time period of the target region and the regional parameters.

[0062] The preset mixed nonlinear runoff model includes a plurality of network branches, and different network branches are respectively used to calculate the runoff of different types of sub-regions in the target region, and the types of the sub-regions at least include a bioretention facility and a permeable pavement.

[0063] After obtaining the rainfall in each time period of the target region by using the rain type model, the rainfall in each time period and the regional parameters can be further input into the pre-set mixed nonlinear runoff model to obtain the total runoff in each time period of the target region. Finally, the total runoff in each time period can be determined according to the total runoff in each time period.

[0064] It should be noted that the mixed nonlinear runoff model of the present embodiment is improved on the basis of the urban nonlinear event gain model (TVGM-urban). The existing TVGM-urban model can only calculate the runoff of green roof facilities in calculating the runoff of LID facilities, and is relatively single, and the final result is not accurate. In order to improve the accuracy of the runoff calculation result and the practicability of the runoff model, the TVGM-urban model is extended and improved.

[0065] Specifically, the preset mixed nonlinear runoff generation model of the embodiment includes a plurality of parallel network branches, each of which corresponds to a model formula, and different network branches are used to calculate the runoff of different types of sub-regions, and the sum of the runoff of all types of sub-regions is the total runoff of the target region. In the application process, a plurality of types of sub-regions can be set according to land use, the target region is divided into a plurality of sub-regions based on the set types, and finally the runoff of each sub-region is calculated by using the preset mixed nonlinear runoff generation model.

[0066] In some embodiments, the types of sub-regions can include bare soil regions, vegetation covered regions, building regions (including impermeable roofs and green roofs in particular), road regions (including impermeable roads and permeable pavements in particular), and bioretention facilities. In addition, the region parameters can include sub-region parameters of each type of sub-region, that is, different types of sub-regions can obtain different sub-region parameters. For example, if the sub-region is a bioretention facility, the sub-region parameters can include (but are not limited to): water level change of the water storage surface layer, height of the overflow weir, inflow of the facility, outflow of the drain pipe, water level of the filter layer, and the like; if the sub-region is a permeable pavement, the sub-region parameters can include (but are not limited to): water storage capacity of the permeable pavement, and thickness, porosity, and the like of each layer of the permeable pavement.

[0067] It is worth mentioning that the existing runoff generation model may need a plurality of sub-region parameters of each sub-region in the calculation process, for example, the area, slope, and elevation of the sub-region, and the like. However, some of the runoff generation model formulas designed in the embodiment of the present application only need the area data of the sub-region in the calculation process, without the need for the slope, elevation, and the like of the sub-region. Thus, the difficulty of data collection is reduced, time and cost are saved, and the practicability of the multi-objective design method of the rainwater storage tank is improved.

[0068] In some embodiments, determining the total runoff of the target region in each period based on the preset mixed nonlinear runoff generation model and the rainfall and region parameters of the target region in each period can include: for any period, respectively inputting each sub-region parameter and rainfall into the corresponding network branch to obtain the runoff of each sub-region in the period, and determining the total runoff of the target region based on the runoff of each sub-region.

[0069] Taking a time period as an example, after obtaining the rainfall and the sub-region parameters of each sub-region, the network branch corresponding to each sub-region can be determined according to the type of each sub-region, and then the sub-region parameters are respectively input into the corresponding network branch; wherein the rainfall is selectively input according to the model formula of each network branch, if the rainfall is a parameter of the model formula of a certain network branch, the rainfall is taken as an input of the network branch. Further, each network branch outputs the runoff of the corresponding sub-region by calculation; after obtaining the runoff of all types of sub-regions, the runoff of all types of sub-regions is summed up, and the total runoff of the target region in this time period can be obtained.

[0070] It should be noted that in the preset mixed nonlinear runoff generation model of the embodiments of the present application, the model formula of the network branch corresponding to the impervious roof, green roof, bare soil area, vegetation covered area and impervious road can use the model formula in the existing TVGM-urban model, which will not be described here. The model formula of the bioretention facility and the model formula of the permeable pavement are designed independently.

[0071] In some embodiments, the sub-region parameters of the bioretention facility type can include the water level change of the water storage surface layer, the height of the overflow weir, the inflow of the bioretention facility, the outflow of the drain pipe, the maximum allowable water level of the filter layer, the water level of the filter layer, the average bottom area of the bioretention facility, and the average porosity of the filter layer.

[0072] The model formula of the network branch corresponding to the bioretention facility type is:

[0073]

[0074] In the formula, is the runoff of the bioretention facility type sub-region, unit: mm; is the runoff reduction coefficient of the bioretention facility; is the water level change of the water storage surface layer at t time period, unit: mm; is the height of the overflow weir; is the inflow of the bioretention facility at t time period; is the outflow of the drain pipe at t time period; is the infiltration of the filter layer at t time period. It should be noted that the above-mentioned water storage surface layer and filter layer respectively refer to the water storage surface layer and filter layer of the bioretention facility.

[0075] The runoff generation calculation formula of the bioretention facility type of the present embodiment (i.e. the above-mentioned model formula) is designed to consider the infiltration, overflow and drain pipe outflow, taking the bioretention pool as a representative, so as to well simulate the time dynamic change of the runoff generation process of the bioretention facility.

[0076] When the rainfall exceeds the maximum water storage capacity of the bioretention facility, or the rainfall intensity is greater than the surface layer infiltration rate, the bioretention facility can overflow. The overflow amount includes the overflow amount of the surface layer into the overflow port and the discharge amount of the drain pipe. In the model formula corresponding to the bioretention facility type, the infiltration amount of the filter layer applies the Darcy equation, and is limited by two conditions that the water storage amount of the water storage surface layer cannot exceed the infiltration amount, and the infiltrated water cannot exceed the available volume of the filter layer within the time step. The calculation formula of the infiltration amount of the filter layer is as follows:

[0077]

[0078] In the formula, is the maximum allowable water level of the filter layer, unit: mm; is the water level of the filter layer at t-1 period, unit: mm; is the water level change amount of the water storage surface layer at t-1 period, unit: mm; is the average bottom area of the bioretention facility, unit: m 2 ; is the average porosity of the filter layer; Δt represents unit time. Wherein, the expression of the unsaturated coefficient is as follows:

[0079]

[0080] In the formula, K s is the saturated hydraulic conductivity coefficient, unit: m / s; K is the unsaturated hydraulic conductivity coefficient, unit: m / s; m is the shape parameter of the medium soil.

[0081] Therefore, by inputting the sub-region parameters of the bioretention facility type sub-region into the above model formula, the runoff of the sub-region can be obtained.

[0082] In some embodiments, the sub-region parameters of the permeable pavement type can include the water storage amount of the permeable pavement, the proportion of the bare soil area type sub-region area to the total area of the target region, the thickness and porosity of each layer of the permeable pavement. Wherein, the permeable pavement includes a surface layer, a leveling layer, a cushion layer and a base layer.

[0083] The model formula corresponding to the network branch of the permeable pavement type is as follows:

[0084]

[0085] In the formula, is the runoff of the permeable pavement type sub-region; is the rainfall amount at t period; is the runoff reduction coefficient of the permeable pavement; W(t) is the water storage amount of the permeable pavement type sub-region at t period; is the proportion of the sub-area area of the bare soil area type to the total area of the target area; W p is the water storage capacity of the pavement layer of the permeable pavement.

[0086] In this embodiment, the water storage capacity W of the pavement layer of the permeable pavement is p The water storage capacity W of the pavement layer of the permeable pavement can be calculated by the following formula:

[0087]

[0088] In the formula, is the thickness of the surface layer; is the porosity of the surface layer; is the thickness of the leveling layer; is the porosity of the leveling layer; is the thickness of the cushion layer; is the porosity of the cushion layer; is the thickness of the base layer; is the porosity of the base layer.

[0089] The runoff calculation formula of the permeable pavement type of this embodiment (i.e., the model formula corresponding to the above permeable pavement type) considers the water storage capacity, convergence area, and outflow of the drain pipe when designing, and regards each layer of the permeable pavement as a pavement structure. It should be noted that the runoff calculation formula of the permeable pavement type of this embodiment does not consider the influence of evapotranspiration.

[0090] Finally, the total runoff R of the target area can be calculated by the following formula:

[0091]

[0092] In the formula, is the runoff of the impervious roof type sub-area; is the runoff of the green roof type sub-area; is the runoff of the impervious road type sub-area; is the runoff of the bare soil area type sub-area; is the runoff of the vegetation cover area type sub-area; is the runoff of the bioretention facility type sub-area; is the runoff of the permeable pavement type sub-area.

[0093] It should be noted that in the model formula of the permeable pavement type and the model formula of the bioretention type, in addition to the rainfall parameter, the parameters to be input include the ratio of each part area to the total area of the target area, the catchment area of the bioretention, the total thickness of the surface layer, the total thickness of the filter layer, the average bottom area of the water storage surface layer, the height of the drain pipe orifice, and the maximum water storage capacity of the pavement layer; the remaining parameters can be obtained by actual flow calibration, which refers to a process of determining the difference between the actual flow and the theoretical flow through a series of measurements and calculations, and adjusting

[0094] Figure 2 is a schematic diagram of the runoff model architecture of the nonlinear time-varying process of the embodiment of the present application. Figure 2 P&C in is the Pilgrim & Cordery rain type, SCS is the SCS rain type, Chicago is the Chicago rain type, and Figure 2 The vegetation area in is the vegetation coverage area described in the embodiment of the present application, and the storage tank is the rainwater storage tank described in the embodiment of the present application. As shown in Figure 2 The embodiment of the present application divides each sub-area in the target area into five types, namely, a building area, a road area, a bioretention, a bare soil area, and a vegetation coverage area. After rainfall in the target area, the rainwater first passes through these types of sub-areas to form runoff. Through the runoff of these sub-areas, the flow of the sub-area can be further obtained. Specifically, by dividing the runoff in a time period by the length of the time period, the flow can be obtained.

[0095] Step 140: determining the pollution load of each time period of the target area based on the total runoff of each time period of the target area and the pollutant parameter.

[0096] Specifically, after obtaining the total runoff of each time period of the target area, the flow of each time period can be calculated using the total runoff of each time period; and the pollution load of each time period of the target area can be calculated based on the flow of each time period and the pollutant parameter.

[0097] Continuing to refer to Figure 2 It can be understood that when the rainwater washes each sub-area, the pollutants on the surface of each sub-area will flow to the drain pipe together with the runoff. As an example, the underlying surface of a building area can contain heavy metal pollutants, which will flow to the drain pipe together with the runoff when washed by rainwater. As another example, the green land can contain pesticides, fertilizers, etc., and when the rainwater washes the underlying surface of the green land, the pollutants in the soil will also flow to the drain pipe together with the runoff.

[0098] In addition, generally, the concentration of pollutants carried by rainwater can be high at the beginning of rainfall, and the concentration of pollutants carried by rainwater can decrease after rainwater has washed for a period of time (i.e., at the middle and late stages of rainfall). Based on this, the embodiments of the present application specifically determine the pollution load of the target area in the following manner.

[0099] In some embodiments, the pollutant parameter includes a beginning pollutant parameter and a middle-late pollutant parameter. Figure 3 FIG. 2 is a flowchart of a rainwater storage tank multi-objective design method according to an embodiment of the present application. As shown in FIG. 2, step 140 determines the pollution load of each time period of the target area based on the total runoff and the pollutant parameter of each time period of the target area, which can include the following steps: Figure 3

[0100] Step 310: Obtain the beginning runoff parameter of the target area.

[0101] Step 320: Divide the rainfall event of the target area into the beginning of rainfall and the middle and late stages of rainfall based on the beginning runoff parameter.

[0102] Step 330: For any time period, if it is determined based on the runoff parameter of the time period that the time period is at the beginning of rainfall, then determine the pollution load of the time period based on the total runoff and the beginning pollutant parameter of the time period.

[0103] Step 340: For any time period, if it is determined based on the runoff parameter of the time period that the time period is at the middle and late stages of rainfall, then determine the pollution load of the time period based on the total runoff and the middle-late pollutant parameter of the time period.

[0104] It should be noted that the beginning runoff parameter can be the beginning runoff millimeter number, the beginning runoff time length, or the beginning runoff concentration, any one of which can be selected; in the present embodiment, the beginning runoff millimeter number can be preferentially selected as the beginning runoff parameter, because the beginning runoff millimeter number is relatively easy to obtain and is relatively accurate for distinguishing the beginning and the middle and late stages. The steps 310-340 will be described in detail below by taking the beginning runoff millimeter number as an example.

[0105] Because the concentration of pollutants in runoff at the beginning of rainfall and the concentration of pollutants in runoff at the middle and late stages of rainfall are quite different, the present embodiment takes the beginning runoff millimeter number as the boundary to divide the rainfall event of the target area into the beginning of rainfall and the middle and late stages of rainfall, so that the pollution load calculated in this way can not only reflect the pollution effect at the beginning of rainfall, but also to some extent reflect the effect of the middle and late stages of rainfall existing in some sub-regions.

[0106] ​Specifically, the current period is determined to be in the early stage of rainfall or in the middle and later stage of rainfall by obtaining the runoff millimeters of each period. If the runoff millimeters of the period is less than the early runoff millimeters, it is determined that the period is in the early stage of rainfall, and at this time, the total runoff and the early pollution parameter of the period can be used to determine the pollution load of the period. If the runoff millimeters of the period is greater than or equal to the early runoff millimeters, it is determined that the period is in the middle and later stage of rainfall, and at this time, the total runoff and the middle and later pollution parameter of the period can be used to determine the pollution load of the period.

[0107] Since the pollutant concentrations in the same period have similarity, in the embodiment, the median or average of all pollutant concentrations in the early stage of rainfall can be selected as the early pollutant parameter, and similarly, the median or average of all pollutant concentrations in the middle and later stage of rainfall can be selected as the middle and later pollutant parameter. By generalizing the early pollutant parameter and the middle and later pollutant parameter, the calculation of the pollution load can be realized by obtaining a small amount of pollutant concentration data, and the entire calculation process of the pollution load is simplified, thereby further reducing the complexity of the design process under the condition of ensuring the accuracy of the calculation result, and improving the practicability of the rainwater storage tank multi-objective design method.

[0108] In the embodiment, the calculation formula of the pollution load can be specifically represented as:

[0109]

[0110] In the formula, is the pollution load of the t period; is the flow of the t period; is the early pollutant concentration, unit: mg / L; is the middle and later pollutant concentration, unit: mg / L; is the early runoff millimeters, unit: mm; and β is the runoff millimeters of the t period.

[0111] In actual application, when the runoff millimeters β of the t period is less than the early runoff millimeters, the flow of the t period can be substituted into the first formula to calculate the pollution load; when the runoff millimeters β of the t period is greater than or equal to the early runoff millimeters, the flow of the t period can be substituted into the second formula to calculate the pollution load.

[0112] Therefore, the pollution load calculation method designed in the embodiment not only considers the early pollution effect and the middle and later pollution effect, so that the final pollution load calculation result is more accurate, but also simplifies the entire calculation process by generalizing the parameters, thereby improving the operation efficiency of the rainwater storage tank multi-objective design.

[0113] Step 150: determining the target parameter of the rainwater storage tank corresponding to the target region based on the total runoff and pollution load of each period of the target region, and taking the reduction of peak flow, the control of non-point source pollution, or the water quality and quantity balance control as the target.

[0114] After obtaining the total runoff and pollution load of each period of the target region, the target parameter of the rainwater storage tank corresponding to the target region can be determined according to the total runoff and pollution load of each period, and taking the reduction of peak flow, the control of non-point source pollution, or the water quality and quantity balance control as the target.

[0115] It should be noted that which factor is used as the control target can be determined according to the underlying surface type of the target region, or selected by the staff according to actual needs. For example, if the target region is an industrial park, the industrial pollution of the industrial park is more serious, and the control of non-point source pollution can be selected as the target, or the water quality and quantity balance control can be selected as the target. If the target region is a park, the reduction of peak flow can be selected as the target, or the water quality and quantity balance control can be selected as the target.

[0116] In some embodiments, step 150 of determining the target parameter of the rainwater storage tank corresponding to the target region based on the total runoff and pollution load of each period of the target region, and taking the reduction of peak flow, the control of non-point source pollution, or the water quality and quantity balance control as the target can include: determining an inflow hydrograph based on the total runoff of each period of the target region, and determining a pollution load hydrograph based on the pollution load of each period of the target region; determining the target parameter of the rainwater storage tank corresponding to the target region based on the inflow hydrograph and taking the reduction of peak flow as the target, or determining the target parameter of the rainwater storage tank corresponding to the target region based on the pollution load hydrograph and taking the control of non-point source pollution as the target, or determining the target parameter of the rainwater storage tank corresponding to the target region based on the inflow hydrograph and the pollution load hydrograph and taking the water quality and quantity balance control as the target.

[0117] The embodiments of the present application provide three rainwater storage tank design methods under different targets, and can adapt to different design targets without modeling, and quickly and accurately obtain the target parameters of the rainwater storage tank. It should be noted that the target parameters of the rainwater storage tank can include (but are not limited to): the volume of the rainwater storage tank, the height of the rainwater storage tank, the position of the orifice, etc.

[0118] Specifically, after obtaining the total runoff and pollution load of each period of the target region, the inflow hydrograph can be obtained according to the total runoff of each period of the target region. The inflow hydrograph is a curve used to describe the change of water flow with time in a specific period of time during the confluence process. Further, the pollution load hydrograph can be determined according to the pollution load of each period of the target region. The pollution load hydrograph is a curve used to describe the change of pollutants with time in a specific period of time.

[0119] It is worth mentioning that the present embodiment only needs the inflow hydrograph because the target area of the present embodiment is a small area, and thus the confluence hydrograph is not needed. Specifically, the present embodiment is ideally applied to a small area, and thus the evaporation and other rainfall losses are ignored in the conversion of the rainfall hydrograph to the inflow hydrograph, and the runoff process is taken as the inflow process. Secondly, due to the complexity of the urban pipe network system, the traditional pipe network confluence models such as the dynamic wave method, the steady wave method and the kinematic wave method, and the equivalent drainage model in the TVGM-urban model all have problems such as too many input parameters, the input of parameters has great uncertainty and needs to be calibrated by measured data (i.e. calibrated and calibrated). However, in actual application, it is usually difficult to obtain the measured data of the outlet flow of the pipe network, and the actual data is greatly disturbed by the real environment, which reduces the reference value. Further, the more the model parameters, the more the complexity of the model, which reduces the applicability of the model. Therefore, the model in the present embodiment ignores the confluence part, and according to some research, the inflow retardation caused by the confluence time in the calculation of the storage tank volume does not have a great influence on the calculation of the capacity, and in a small area, the runoff process can be directly converted into the inflow flow process.

[0120] FIG. 4(a) is a schematic diagram of an inflow hydrograph of one specific embodiment of the present application, and the inflow hydrograph described in the present embodiment can refer to FIG. 4(a). FIG. 4(b) is a schematic diagram of a pollution load hydrograph of one specific embodiment of the present application, and the pollution load hydrograph described in the present embodiment can refer to FIG. 4(b).

[0121] After the inflow hydrograph and the pollution load hydrograph are determined, the target parameters of the rainwater storage tank can be determined in the following three ways. The first way is to determine the target parameters of the rainwater storage tank corresponding to the target area based on the inflow hydrograph and taking the reduction of peak flow as the target. The second way is to determine the target parameters of the rainwater storage tank corresponding to the target area based on the pollution load hydrograph and taking the control of non-point source pollution as the target. The third way is to determine the target parameters of the rainwater storage tank corresponding to the target area based on the inflow hydrograph and the pollution load hydrograph and taking the balanced control of water quality and water quantity as the target.

[0122] The above three ways will be described in detail below.

[0123] In some embodiments, the first way of determining the target parameters of the rainwater storage tank corresponding to the target area based on the inflow hydrograph and taking the reduction of peak flow as the target can include: taking the downstream design flow of the rainwater storage tank as the control standard, and determining a first time and a second time based on the inflow hydrograph; determining a first effective volume based on the first time and the second time by using a preset first volume formula, and determining the target parameters of the rainwater storage tank corresponding to the target area based on the first effective volume.

[0124] In the embodiment, the storage tank volume calculation method aiming at reducing peak flow mainly takes downstream design flow as control standard and calculates with peak reduction amount, peak reduction rate and runoff total amount control rate as evaluation indexes.

[0125] Figure 5 is a schematic diagram of an inflow hydrograph and downstream design flow of one specific embodiment of the present application. As shown, Figure 5 Figure 5 the ordinate Q in the diagram represents flow, and the abscissa T represents time, Figure 5 the horizontal line in the diagram represents downstream design flow, and the area enclosed by the horizontal line above and the inflow hydrograph below is the volume required for reducing peak flow, i.e. the first effective volume V1 of the storage tank, and the abscissas of the two intersection points of the horizontal line representing downstream design flow and the inflow hydrograph are the first time and the second time, respectively. The preset first volume formula aiming at reducing peak flow is as follows:

[0126]

[0127] In the formula, V1 is the first effective volume calculated aiming at reducing peak flow; Q(t) is the inflow hydrograph; Qd is downstream design flow; a is the time corresponding to the first intersection point of the horizontal line representing downstream design flow and the inflow hydrograph (i.e. the first time); and b is the time corresponding to the second intersection point of the horizontal line representing downstream design flow and the inflow hydrograph (i.e. the second time).

[0128] After obtaining the first effective volume, the bottom area of the storage tank can be designed according to the specifications of the target area, and the final storage tank volume, storage tank height and orifice position are calculated based on the first effective volume and the bottom area of the storage tank. The calculation assumes that the downstream is gravity outflow, and the calculation method of the storage tank in the model is developed based on the runoff total amount control method, which includes downstream design flow and storage tank control effect index.

[0129] Therefore, the storage tank volume calculation method aiming at reducing peak flow of the embodiment can accurately grasp the peak reduction position and the reduced peak flow, and the calculation result is more accurate compared with the traditional runoff total amount control method, which greatly reduces the effective volume of the storage tank.

[0130] In some embodiments, the second method, which determines the target parameters of the rainwater storage tank corresponding to the target area based on the pollution load hydrograph and aiming at controlling non-point source pollution, can include: taking the pollution control rate of the rainwater storage tank as the control standard and determining the third time based on the pollution load hydrograph; determining the second effective volume by using the preset second volume formula and based on the third time, and determining the target parameters of the rainwater storage tank corresponding to the target area based on the second effective volume.​

[0131] In the present embodiment, the calculation method of the storage tank volume for the purpose of controlling non-point source pollution mainly takes the pollution control rate of the rainwater storage tank as the control standard for calculation. Among them, the settling process provides two ways of first-order decay equation and Stokes formula to calculate the detention time. In the rainwater storage tank, the settlement of pollution particles is very important for water quality purification, and different regional pollution concentration characteristics require different settling times. The detention time is mainly solved by the type, concentration and water quality treatment requirements of the pollutants in the storage tank, which is closely related to the volume and other parameters of the storage tank. The decay constant in the first-order decay equation reflects the decay of pollutants in the storage tank, which is affected by the volume of the storage tank, and the larger the volume, the larger the decay constant. When the current pollution concentration in the tank is settled and decayed to meet the outflow concentration standard, it is the detention time under the first-order decay equation. The Stokes formula involves parameters such as particle radius, fluid viscosity and particle settling velocity, which are related to the concentration of pollutants in the tank. Through the above parameters, the settling velocity of the pollutant particles in the tank can be obtained, and then the settling height is calculated by the tank area parameter, and the settling time is the settling height / settling velocity.

[0132] Figure 6 is a schematic diagram of the pollution load hydrograph and the pollution control rate of one specific embodiment of the present application. As shown in Figure 6 , the vertical coordinate Q in Figure 6 represents the flow rate, and the horizontal coordinate T represents the time, Figure 6 , the vertical line in is the pollution control rate, the vertical line on the left, the pollution load hydrograph on the right, and the area surrounded by the horizontal axis of the coordinate system is the second effective volume V2 of the rainwater storage tank, and then the horizontal coordinate of the intersection point of the vertical line representing the pollution control rate and the pollution load hydrograph is the third time. The preset second volume formula for the purpose of controlling non-point source pollution is as follows:

[0133]

[0134] In the formula, is the second effective volume calculated for the purpose of controlling non-point source pollution; is the inflow hydrograph; c is the time corresponding to the pollution load when the pollution control rate is reached (i.e. the third time). It should be noted that the third time c can be determined in advance according to the intersection point of the pollution load hydrograph and the pollution control rate, which is directly substituted here.

[0135] Similarly, after obtaining the second effective volume, the bottom area of the storage tank can also be designed according to the specifications of the target area, and the final storage tank volume, storage tank height and orifice position can be calculated based on the second effective volume and the bottom area of the storage tank, which will not be described here.

[0136] Therefore, the storage tank volume calculation method of the embodiment, which aims at controlling surface pollution, considers the pollution load in the middle and later stages, and stops at the position where the pollution control rate reaches the total pollution, and thus can be applied to some areas with later-stage flushing effect.

[0137] In some embodiments, the third method, which determines the target parameters of the rainwater storage tank corresponding to the target area based on the inflow hydrograph and the pollution load hydrograph and aiming at water quality and water quantity balance control, can include: taking the peak flow reduction rate of the rainwater storage tank as the control standard, determining the first time and the second time based on the inflow hydrograph, and determining the first effective volume by using the preset first volume formula, the first time and the second time; taking the pollution control rate of the rainwater storage tank as the control standard, determining the third time based on the pollution load hydrograph, and determining the second effective volume by using the preset second volume formula, the third time; selecting a maximum value from the first effective volume and the second effective volume, and determining the target parameters of the rainwater storage tank corresponding to the target area based on the maximum value.

[0138] In the embodiment, water quality and water quantity are mainly taken as control targets, wherein the water quantity takes the peak flow reduction rate as the control standard, and the water quality still takes the pollution control rate as the control standard, and the downstream design flow and the runoff total amount control rate are taken as evaluation indexes to jointly determine the volume of the rainwater storage tank.

[0139] Figure 7 is a schematic diagram of the peak flow reduction rate and the pollution control rate of one specific embodiment of the present application. It should be noted that, in order to clearly show the relationship between the peak flow reduction rate and the pollution control rate, Figure 7 The inflow hydrograph and the pollution load hydrograph in Figure 7 are represented by the same curve. As shown in Figure 7 The ordinate Q in Figure 7 represents the flow, and the abscissa T represents the time; if the curve in Figure 7 is the inflow hydrograph, then the horizontal line in is the peak flow reduction rate, and the area surrounded by the inflow hydrograph above the horizontal line is the volume required for reducing the peak flow, i.e., the first effective volume V1 of the storage tank, and the abscissas of the two intersection points of the horizontal line and the inflow hydrograph represent the first time and the second time, respectively. Specifically, a first effective volume V1 can be determined by using the above-mentioned preset first volume formula, the first time and the second time, and the calculation process can refer to the process of the foregoing embodiments, which will not be described here again.

[0140] Figure 7 Continuing to refer to Figure 7 , if the curve in Figure 8The vertical line in the figure is the pollution control rate, the area surrounded by the vertical line on the left, the pollution load process line on the right, and the horizontal axis of the coordinate system is the second effective volume V2 of the rainwater storage tank, and the horizontal coordinate of the intersection point of the vertical line representing the pollution control rate and the pollution load process line is the third time. A second effective volume V2 can be determined by using the above-mentioned preset second volume formula and the third time. The calculation process can refer to the process of the foregoing embodiments, which will not be described here.

[0141] After obtaining the first effective volume V1 and the second effective volume V2, the final effective volume V can be determined by the following formula:

[0142]

[0143] Similarly, after obtaining the second effective volume, the bottom area of the storage tank can also be designed according to the specifications of the target area, and the final storage tank volume, storage tank height and orifice position can be calculated based on the second effective volume and the bottom area of the storage tank, which will not be described here.

[0144] Therefore, the storage tank volume calculation method of the embodiment with water quality and water quantity balance control as the target adopts dual indicators of peak flow reduction rate and pollution control rate for calculation, which can meet the requirements of reducing peak flow and controlling runoff pollution at the same time, so that the target parameter calculation result of the rainwater storage tank is more accurate and reasonable.

[0145] It is worth mentioning that the rainwater storage tank multi-objective design method based on runoff and pollution of the embodiment can be realized by using EXCEL and Python program. Specifically, the rainfall parameters, regional parameters and pollutant parameters of the target area can be input into an EXCEL file, and then the rainwater storage tank multi-objective design method of the embodiment can be converted into an application program by using Python language. The application program can directly call the required data from the EXCEL file during execution, and the execution result of the final application program (i.e. the rainwater storage tank target parameters under three targets) can also be output to the EXCEL file for display. Therefore, without the need to build a model and simulate LID facilities, the rainfall, runoff, pollution load and storage tank configuration parameters, benefit indicators and other data can be quickly and accurately obtained to assist the fine design of rainwater storage tanks in the construction of sponge cities.

[0146] The implementation process of the Python program will be further described below through a specific example.

[0147] First, input the rainfall parameters, area parameters and pollutant parameters of the target area in Excel. After inputting the parameters, make sure that Excel is closed, and then run the Python application. The input table is named "Detention Tank Calculation.xlsx" at present, and the results will be automatically saved in a new Excel file named "Detention Tank Calculation_output.xlsx" after running the code. The new file will maintain the interface of the original table. Changes will also be made in the output table. If you need to change the file path or name, you need to change the name in the Python code accordingly. It is recommended not to share the parameter input table with the result output table, as this may cause the file to be damaged and cannot be recovered. The application runs in four stages, which are described below:

[0148] First, input the original data of the target area. You can directly input the specified parameters in Excel. The first stage of automatic operation of the detention tank is to design the rain type. After closing the Excel file with input parameters, run the "Chicagorainfall.py" file to complete the calculation. The file results are displayed in "Detention Tank Calculation_output.py", which can be opened for checking.

[0149] The second stage of automatic operation of the detention tank is to calculate the runoff of the target area. You need to input the actual flow and the previous impact rainfall to calibrate and verify. After calibration and verification, you can normally calculate. Close the "Detention Tank Calculation_output.py" file and run the "rainoff.py" file.

[0150] The third stage of automatic operation of the detention tank is to calculate the pollutant load and inflow process line of the target area. Close the "Detention Tank Calculation_output.py" file and run the "pollution load.py" file.

[0151] The fourth stage of automatic operation of the detention tank is the calculation of the volume of the detention tank. The volume calculation includes three modules: peak flow reduction type, pollution control type and comprehensive control type. Users can choose to calculate according to their needs. Close the "Detention Tank Calculation_output.py" file and run the "detention tank volume-peak flow reduction.py" file for peak flow reduction, or run the "detention tank volume-pollution reduction.py" file for pollution control, or run the "detention tank volume-combined.py" file for comprehensive control.

[0152] The user can customize the file name and path of the input file Excel, but it needs to match the Python file. All output data of the software is in the form of a new Excel file in the current path, with the suffix "_output". The user can change it according to the needs in the code. The output file is displayed in the original table form.

[0153] Therefore, the rainwater storage tank multi-objective design method of the embodiment of the application simplifies the calculation model NTVP-SDT and provides a more refined and simple storage tank volume calculation method. The nonlinear rainfall runoff response of each land use type of urban surface, the pollutant concentration flushing process of the field rainfall event, the index correlation, and the difference of the storage tank calculation volume under three different targets are considered. The embodiment of the application has the following advantages:

[0154] (1) The runoff calculation method based on the nonlinear process provided in the embodiment of the application has fewer required parameters, higher accuracy of calculation results, and high operation efficiency. Compared with the commonly used SWMM model, the nonlinear process of runoff can be better described and more refined results can be obtained, and a large amount of pipe network geological data is not required for modeling, which is low in cost and easy to use.

[0155] (2) The two-stage pollution load calculation method provided in the embodiment of the application greatly simplifies the calculation process, effectively avoids the shortcomings of water quality monitoring, and has a simple structure and is easy to calculate.

[0156] (3) Through the self-developed rainfall, runoff, pollution, and storage tank calculation method, a sub-application program is made, and each module of the application program can be used alone or integrally used to calculate the target parameters of the storage tank. The structure between the modules of the application program is clear and easy to optimize and improve. Through the storage tank design under three targets, targeted design can be realized. Compared with the commonly used empirical formula, the calculation is simple while effectively avoiding overdesign; compared with the rainwater model, iteration calculation is not required and modeling is not required, which ensures the calculation accuracy while greatly improving the operation speed.

[0157] Figure 8 An example of an entity structure diagram of an electronic device is shown in FIG. 1. ​As shown, the electronic device can include a processor 810, a communication interface 820, a memory 830, and a communication bus 840, wherein the processor 810, the communication interface 820, and the memory 830 complete communication with each other through the communication bus 840. The processor 810 can invoke the logic instructions in the memory 830 to execute the multi-objective design method of the rainwater storage tank based on runoff and pollution, including: obtaining rainfall parameters, regional parameters, and pollutant parameters of a target region; determining the rainfall of each period of the target region based on the rainfall parameters; determining the total runoff of each period of the target region by using a preset mixed nonlinear runoff model and based on the rainfall of each period of the target region and the regional parameters; wherein the preset mixed nonlinear runoff model includes multiple network branches, and different network branches are respectively used to calculate the runoff of different types of sub-regions in the target region, and the types of the sub-regions at least include a bioretention facility and a permeable pavement; determining the pollution load of each period of the target region based on the total runoff of each period of the target region and the pollutant parameters; and determining the target parameters of the corresponding rainwater storage tank of the target region based on the total runoff of each period of the target region and the pollution load, and taking the reduction of peak flow, the control of non-point source pollution, or the balanced control of water quality and quantity as the target.

[0158] In addition, the logic instructions in the memory 830 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0159] On the basis of the above-mentioned embodiments, in another aspect, the present application also provides a computer program product, the computer program product comprising a computer program, the computer program being stored on a non-transitory computer-readable storage medium, and the computer program being executable by a processor to enable a computer to perform the multi-objective design method of a rainwater storage tank based on runoff and pollution provided by the above-mentioned methods, comprising: obtaining rainfall parameters, regional parameters and pollutant parameters of a target region; determining rainfall amounts of each period of the target region based on the rainfall parameters; determining total runoff amounts of each period of the target region by using a preset mixed nonlinear runoff model and based on the rainfall amounts of each period of the target region and the regional parameters; wherein the preset mixed nonlinear runoff model comprises a plurality of network branches, and different network branches are respectively used to calculate runoff amounts of different types of sub-regions in the target region, and the types of the sub-regions at least include a bioretention facility and a permeable pavement; determining pollution loads of each period of the target region based on the total runoff amounts of each period of the target region and the pollutant parameters; and determining target parameters of a rainwater storage tank corresponding to the target region based on the total runoff amounts of each period of the target region and the pollution loads, and taking reduction of peak flow, control of non-point source pollution or water quality and water quantity balance control as the target.

[0160] On the basis of the above-mentioned embodiments, in still another aspect, the present application also provides a non-transitory computer-readable storage medium having a computer program stored thereon, the computer program being executable by a processor to implement the multi-objective design method of a rainwater storage tank based on runoff and pollution provided by the above-mentioned methods, comprising: obtaining rainfall parameters, regional parameters and pollutant parameters of a target region; determining rainfall amounts of each period of the target region based on the rainfall parameters; determining total runoff amounts of each period of the target region by using a preset mixed nonlinear runoff model and based on the rainfall amounts of each period of the target region and the regional parameters; wherein the preset mixed nonlinear runoff model comprises a plurality of network branches, and different network branches are respectively used to calculate runoff amounts of different types of sub-regions in the target region, and the types of the sub-regions at least include a bioretention facility and a permeable pavement; determining pollution loads of each period of the target region based on the total runoff amounts of each period of the target region and the pollutant parameters; and determining target parameters of a rainwater storage tank corresponding to the target region based on the total runoff amounts of each period of the target region and the pollution loads, and taking reduction of peak flow, control of non-point source pollution or water quality and water quantity balance control as the target.

[0161] The device embodiments described above are only schematic, wherein the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Part or all of the modules can be selected to achieve the purpose of the present embodiment scheme according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0162] Those skilled in the art can clearly understand the implementation of the embodiments by means of software and necessary general hardware platforms through the description of the above embodiments, and of course, the embodiments can also be implemented by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, and the computer software product can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

Claims

1. A multi-objective design method for rainwater storage tanks based on runoff and pollution, characterized in that, include: Obtain rainfall parameters, regional parameters, and pollutant parameters for the target area; The rainfall amount in the target area at each time period is determined based on the rainfall parameters; Using a pre-defined hybrid nonlinear runoff generation model and based on the rainfall in the target area at different time periods and the regional parameters, the total runoff in the target area at different time periods is determined; wherein, the pre-defined hybrid nonlinear runoff generation model includes multiple network branches, and different network branches are used to calculate the runoff in different types of sub-regions in the target area, and the types of sub-regions include at least bioretention facilities and permeable pavement; The pollution load of the target area for each time period is determined based on the total runoff of the target area for each time period and the pollutant parameters; Based on the total runoff and pollution load of the target area at each time period, and with the goal of reducing peak flow, controlling non-point source pollution or water quality and quantity balance control, the target parameters of the corresponding rainwater storage tank in the target area are determined. The sub-regional parameters of the bioretention facility include at least the water level change of the water storage surface, the height of the overflow weir, the inflow rate of the bioretention facility, and the outflow rate of the drainage pipe. The model formula for the network branch corresponding to the bioretention facility is: In the formula, The runoff of the sub-region of the bioretention facility; The runoff reduction factor for the bioretention facility; Let t be the change in water level at the surface of the water storage layer during time period t; The height of the overflow weir; The inflow rate of the bioretention facility during time period t; Let t be the outflow rate of the drainage pipe during time period t; The infiltration rate of the filter layer during time period t; The sub-region parameters of the permeable pavement include at least the water storage capacity and the proportion of the area of ​​the bare soil sub-region to the total area of ​​the target area. The model formula for the network branch corresponding to the permeable pavement is: In the formula, The runoff volume of the permeable pavement sub-area; The rainfall during period t; is the runoff reduction factor for permeable pavement; W(t) is the water storage capacity of the permeable pavement sub-region during time period t; W represents the proportion of the area of ​​the sub-region of the bare soil region to the total area of ​​the target region. p This refers to the water capacity of the permeable pavement layer.

2. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 1, characterized in that, The types of sub-regions also include bare soil areas, vegetation-covered areas, impermeable roofs, green roofs, and impermeable roads, and the region parameters include the sub-region parameters for each type of sub-region; The step of determining the total runoff volume of the target area for each time period using a preset hybrid nonlinear runoff generation model and based on the rainfall and regional parameters of the target area for each time period includes: For any given time period, the parameters of each sub-region and the rainfall are input to the corresponding network branch to obtain the runoff of each sub-region during that time period, and the total runoff of the target region is determined based on the runoff of each sub-region.

3. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 1, characterized in that, The pollutant parameters include initial pollutant parameters and mid-to-late stage pollutant parameters. Determining the pollution load of the target area for each time period based on the total runoff and the pollutant parameters in the target area includes: Obtain the initial flow rejection parameters for the target area; Based on the initial flow diversion parameters, the rainfall events in the target area are divided into the initial rainfall phase and the middle and late rainfall phases. For any given time period, if it is determined that the time period is in the initial stage of rainfall based on the runoff parameters of that time period, then the pollution load of that time period is determined based on the total runoff and the initial pollutant parameters of that time period. For any given time period, if the time period is determined to be in the middle or late stage of the rainfall based on the runoff parameters of that time period, then the pollution load of that time period is determined based on the total runoff of that time period and the pollutant parameters of the middle and late stage.

4. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 1, characterized in that, The determination of target parameters for the corresponding stormwater storage tanks in the target area, based on the total runoff and pollution load of the target area at different time periods, with the aim of reducing peak flow, controlling non-point source pollution, or achieving water quality and quantity balance control, includes: The inflow process line is determined based on the total runoff in the target area during each time period, and the pollution load process line is determined based on the pollution load in the target area during each time period. Based on the inflow process line, the target parameters of the rainwater storage tank corresponding to the target area are determined with the goal of reducing peak flow; or, based on the pollution load process line, the target parameters of the rainwater storage tank corresponding to the target area are determined with the goal of controlling non-point source pollution; or, based on the inflow process line and the pollution load process line, the target parameters of the rainwater storage tank corresponding to the target area are determined with the goal of water quality and quantity balance control.

5. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 4, characterized in that, The determination of target parameters for the stormwater storage tank corresponding to the target area based on the inflow process line and with the goal of reducing peak flow includes: The downstream design flow rate of the rainwater storage tank is used as the control standard, and the first and second times are determined based on the inflow process line. The first effective volume is determined by using a preset first volume formula and based on the first time and the second time, and the target parameters of the rainwater storage tank corresponding to the target area are determined based on the first effective volume.

6. The multi-objective design method for stormwater storage tanks based on runoff and pollution according to claim 4, characterized in that, The determination of target parameters for the corresponding stormwater storage tank in the target area based on the pollution load process line and with the goal of controlling non-point source pollution includes: The pollution control rate of the rainwater storage tank is used as the control standard, and the third time is determined based on the pollution load process line; The second effective volume is determined using a preset second volume formula and based on the third time, and the target parameters of the rainwater storage tank corresponding to the target area are determined based on the second effective volume.

7. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 4, characterized in that, The determination of target parameters for the corresponding stormwater storage tank in the target area, based on the inflow process line and the pollution load process line, with the goal of water quality and quantity balance control, includes: The peak flow reduction rate of the rainwater storage tank is used as the control standard, and the first time and the second time are determined based on the inflow process line. The first effective volume is determined by using a preset first volume formula, the first time and the second time. The pollution control rate of the rainwater storage tank is used as the control standard, and a third time is determined based on the pollution load process line. The second effective volume is determined using a preset second volume formula and the third time. Select the maximum value from the first effective volume and the second effective volume, and determine the target parameters of the rainwater storage tank corresponding to the target area based on the maximum value.

8. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the multi-objective design method for stormwater storage tanks based on runoff and pollution as described in any one of claims 1 to 7.

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