Rainwater storage pond multi-objective design method and equipment based on runoff and pollution

Abstract

The invention discloses a rainwater storage pond multi-objective design method and device based on runoff and pollution, and relates to the technical field of urban drainage. The method comprises the following steps: acquiring rainfall parameters, area parameters and pollutant parameters of a target area; determining the rainfall capacity of the target area in each time period based on the rainfall parameters; determining the total runoff volume of the target area in each time period by using a preset mixed nonlinear runoff production model and based on the rainfall and the area parameters of the target area in each time period; determining the pollution load of the target area in each time period based on the total runoff volume and pollutant parameters of the target area in each time period; and based on the total runoff volume and pollution load of the target area in each time period, determining target parameters of the rainwater regulation and storage pool corresponding to the target area by taking reduction of peak flow, control of non-point source pollution or water quality and water quantity balance control as targets. Therefore, the calculation precision of the key parameters of the rainwater storage tank is improved, and the dependence on data is reduced.

Description

Technical Field

[0001] The present application relates to the field of urban drainage technology, and in particular to a multi-objective design method and equipment for a rainwater storage tank based on runoff and pollution. Background Art

[0002] As one of the infrastructures for gray rainwater treatment in low impact development (LID), rainwater storage tanks play an important role in runoff pollution control, runoff water storage, and peak flow reduction. The key parameter calculation methods of rainwater storage tanks mainly include simplified empirical formula calculation method and rainwater model calculation method.

[0003] Among them, the simplified empirical formula calculation method mainly calculates the key parameters of the rainwater storage tank directly through empirical formulas. The current simplified empirical formula calculation method does not clearly define the regulation and optimization objectives during the calculation process, and most simplified empirical formulas use empirical parameters. Most of these empirical parameters have thresholds. Different selected parameters will also produce a large bias in the final calculation results. Therefore, the calculation accuracy of the simplified empirical formula calculation method is low.

[0004] The stormwater model calculation method mainly calculates the key parameters of the rainwater storage tank through the runoff model, pipe network model and water quality calculation module. However, its runoff model simply divides the underlying surface into permeable areas and impermeable areas for runoff calculation, which cannot well describe the nonlinear runoff characteristics in hydrological phenomena. Moreover, these stormwater models need to input a large amount of data required for modeling when establishing pipe network models and simulating the runoff and pollution load of LID facilities. Therefore, this method is highly dependent on data. Summary of the invention

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

[0006] To achieve the above objectives, the present application provides a multi-objective design method for a rainwater storage tank based on runoff and pollution, including: Obtain rainfall parameters, regional parameters and pollutant parameters of the target area; Determine the rainfall in each time period of the target area based on the rainfall parameter; Determine the total runoff volume of the target area in each period of time by using a preset hybrid nonlinear runoff generation model and based on the rainfall in each period of time of the target area and the regional parameters; wherein the preset hybrid nonlinear runoff generation model includes a plurality of network branches, and different network branches are used to calculate the runoff volume of different types of sub-areas in the target area, and the types of the sub-areas include at least bioretention facilities and permeable pavement; Determine the pollution load of the target area at each time period based on the total runoff volume of the target area at each time period and the pollutant parameter; Based on the total runoff and pollution load in each time period of the target area, and with the goal of reducing peak flow, controlling surface source pollution or controlling water quality and water quantity balance, the target parameters of the rainwater storage tank corresponding to the target area are determined.

[0007] Optionally, the types of sub-areas also include bare soil areas, vegetation-covered areas, impermeable roofs, green roofs and impermeable roads, and the regional parameters include sub-area parameters of each type of sub-area; the total runoff of the target area for each time period is determined by 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, including: for any time period, inputting each sub-area parameter and the rainfall into a corresponding network branch, respectively, to obtain the runoff of each sub-area in the time period, and determining the total runoff of the target area based on the runoff of each sub-area.

[0008] Optionally, the sub-region 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 of the bioretention facility, and the outflow of the drainage pipe; the model formula of the network branch corresponding to the bioretention facility is:

[0009] In the formula, is the runoff volume of the sub-area of ​​the bioretention facility; is the runoff reduction factor for the bioretention facility; is the water level change of the water storage surface during period t; is the height of the overflow weir; is the inflow to the bioretention facility during period t; is the outflow of the drainage pipe during period t; is the infiltration amount of the filter layer during period t.

[0010] Optionally, the sub-region parameters of the permeable pavement include at least water storage capacity and the proportion of the sub-region area of ​​the bare soil area to the total area of ​​the target area; the model formula of the network branch corresponding to the permeable pavement is:

[0011] In the formula, is the runoff volume of the permeable pavement sub-area; is the rainfall in period t; is the runoff reduction coefficient of the permeable pavement; W(t) is the water storage capacity of the permeable pavement sub-area in time period t; W is the ratio of the sub-region area of ​​the bare soil region to the total area of ​​the target region; p The water capacity of the pavement layer of permeable pavement.

[0012] Optionally, the pollutant parameters include initial pollutant parameters and mid- and late-stage pollutant parameters, and the pollution load of each time period of the target area is determined based on the total runoff volume of each time period of the target area and the pollutant parameters, including: obtaining the initial abandonment parameter of the target area; dividing the rainfall event in the target area into an initial rainfall period and a mid- and late-stage rainfall period based on the initial abandonment parameter; for any time period, if it is determined that the time period is in the initial rainfall period based on the abandonment parameter of the time period, then the pollution load of the time period is determined based on the total runoff volume of the time period and the initial pollutant parameters; for any time period, if it is determined that the time period is in the mid- and late-stage rainfall based on the abandonment parameter of the time period, then the pollution load of the time period is determined based on the total runoff volume of the time period and the mid- and late-stage pollutant parameters.

[0013] Optionally, the target parameters of the rainwater storage tank corresponding to the target area are determined based on the total runoff and pollution load of the target area in each time period, with the goal of reducing peak flow, controlling non-point source pollution or controlling water quality and water quantity balance, including: determining the inflow process line based on the total runoff of the target area in each time period, and determining the pollution load process line based on the pollution load of the target area in each time period; determining the target parameters of the rainwater storage tank corresponding to the target area based on the inflow process line, with the goal of reducing peak flow; or, determining the target parameters of the rainwater storage tank corresponding to the target area based on the pollution load process line, with the goal of controlling non-point source pollution; or, determining the target parameters of the rainwater storage tank corresponding to the target area based on the inflow process line and the pollution load process line, with the goal of controlling water quality and water quantity balance.

[0014] Optionally, the target parameters of the rainwater storage tank corresponding to the target area are determined based on the inflow process line and with the goal of reducing peak flow, including: taking the downstream design flow of the rainwater storage tank as the control standard, and determining the first time and the second time based on the inflow process line; determining the first effective volume based on the first time and the second time 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.

[0015] Optionally, the target parameters of the rainwater storage tank corresponding to the target area are determined based on the pollution load process line and with the goal of controlling surface source pollution, including: taking the pollution control rate of the rainwater storage tank as a control standard, and determining a third time based on the pollution load process line; determining a second effective volume based on the third time using a preset second volume formula, and determining the target parameters of the rainwater storage tank corresponding to the target area based on the second effective volume.

[0016] Optionally, the target parameters of the rainwater storage tank corresponding to the target area are determined based on the inflow process line and the pollution load process line with the goal of water quality and water quantity balance control, including: taking the peak flow reduction rate of the rainwater storage tank as the control standard, and determining the first time and the second time based on the inflow process line, 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, and determining the third time based on the pollution load process line, and determining the second effective volume by using the preset second volume formula and 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.

[0017] In addition, to achieve the above-mentioned objectives, the present application also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the processor executes the program, a multi-objective design method for a rainwater storage tank based on runoff and pollution as described in any one of the above-mentioned methods is implemented.

[0018] The multi-objective design method for rainwater storage tanks based on runoff and pollution of the present application can calculate the runoff of different types of sub-areas in the target area by presetting a mixed nonlinear runoff model, and then determine the total runoff of the target area by the runoff of each type of sub-area, that is, the influence of the underlying surface type on the runoff calculation is taken into account, thereby improving the accuracy of the runoff calculation for the target area; secondly, by considering the two aspects of runoff and pollution generation, the target parameters of the rainwater storage tank are calculated with the control objectives of reducing peak flow, controlling surface source pollution or controlling water quality and water quantity balance, which not only clarifies the control objectives, but also increases the number of control objectives, thereby further improving the calculation accuracy of the target parameters of the rainwater storage tank; finally, the multi-objective design method for rainwater storage tanks of the present application does not require the establishment of a model, but can quickly calculate the target parameters of the rainwater storage tank by simulating LID facilities, reducing dependence on data. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is one of the flow charts of the multi-objective design method of the rainwater storage tank in the embodiment of the present application; Figure 2 is a schematic diagram of a flow generation model framework of a nonlinear time-varying process in an embodiment of the present application; Figure 3 This is the second flow chart of the multi-objective design method for a rainwater storage tank according to an embodiment of the present application; FIG4( a ) is a schematic diagram of an inflow process line of a specific embodiment of the present application; FIG4( b ) is a schematic diagram of a pollution load process line of a specific embodiment of the present application; Figure 5 is a schematic diagram of an inflow process line and a downstream design flow rate of a specific embodiment of the present application; Figure 6 is a schematic diagram of a pollution load process line and a pollution control rate of a specific embodiment of the present application; Figure 7 is a schematic diagram of a peak flow reduction rate and a pollution control rate of a specific embodiment of the present application; Figure 8 An example of a physical structure diagram of an electronic device is provided; In the figure, 810 is a processor; 820 is a communication interface; 830 is a memory; and 840 is a communication bus.

[0020] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] As one of the infrastructures for gray rainwater treatment in low impact development (LID), rainwater storage tanks play an important role in runoff pollution control, runoff water storage, and flood peak flow reduction. The calculation methods of key parameters of rainwater storage tanks can be divided into two categories: simplified empirical formula calculation method and rainwater flood model calculation method.

[0023] Among them, the simplified empirical formula calculation method mainly directly calculates the key parameters of the rainwater storage tank through empirical formulas. At present, the existing simplified empirical formula calculation methods for the storage tank volume include the triangle flow process line method, the accumulation indication method, the simple method, the escape coefficient method, etc. These empirical formulas are all based on empirical parameters to directly calculate the key parameters of the rainwater storage tank, so there are the following problems: First, the simplified empirical formula calculation method does not clearly define the control target during the calculation process. Although most of the existing simplified empirical formulas are calculated with the goal of reducing peak flow, the control target does not play a big 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 reduction obtained is the reduction of the total runoff. For the goal of reducing peak flow, it will lead to an overly large volume design, resulting in a waste of resources.

[0024] Secondly, the empirical formulas of simplified empirical formula calculation methods generally use empirical parameters. Most of the empirical parameters have thresholds. If the selected empirical parameters are different, the final calculation results will also be greatly biased. For example, if the goal is to control non-point source pollution, the key to the design of the storage tank is the interception conditions of the initial rainwater. Different countries have different interception standards, including runoff depth, rainfall time, rainfall, and pollution load. For another example, in the calculation formula of the storage tank with the goal of controlling runoff pollution, most of them quote runoff depth or time as parameters, but because the definition of initial rainwater is affected by multiple factors such as rainfall conditions and underlying surface type, the value is uncertain. Defining initial rainwater by pollution load has the best effect on pollution control, but water quality changes are difficult to control. Even in areas with more serious pollution, the pollutants in the entire runoff are higher than the defined value.

[0025] Furthermore, the rainwater model calculation method mainly calculates the key parameters of the rainwater storage tank through the flow model, pipe network model and water quality calculation module. The rainwater model uses computer models and simulation technology to quickly select, compare and evaluate design plans, which can effectively improve the reliability of the storage tank design and operation.

[0026] At present, the commonly used stormwater model is the SWMM model, which contains a runoff model, a pipe network model and a water quality calculation module, and can use different calculation methods according to the calculation accuracy requirements. However, in the runoff part, the SWMM model mainly uses an empirical formula based on infiltration, and simply divides the underlying surface types into two types: permeable areas and impermeable areas. This simple classification cannot well describe the nonlinear runoff characteristics in hydrological phenomena. Especially for urban underlying surfaces with LID facilities, the nonlinearity of the urban underlying surface hydrological process is more complex and significant; rainfall intensity, soil infiltration capacity, soil porosity, hydraulic 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.

[0027] In addition, when modeling and simulating the runoff and pollution load of LID facilities, these stormwater models need to input a large amount of various data to support the modeling and simulation process, such as urban terrain data, sewer network data, etc. Therefore, the data requirements and dependence are high, and the actual application of data in areas and projects is limited. It should be noted here that areas lacking data refer to areas lacking terrain data, sewer network data and other data.

[0028] Some scholars have used long-sequence hydrological data measured in basins in more than 60 different climate regions around the world to analyze and obtain the inherent power function relationship of the earth's hydrological system, and further proposed a corresponding time-varying gain model. At present, many scholars have improved it and developed a nonlinear event gain model based on cities (TVGM-urban), which divides the urban underlying surface into vegetation coverage areas, bare soil areas, impervious roofs, green roofs, and impervious underlying surfaces. Some studies have compared TVGM-urban with the Horton and SCSCN models, indicating that the TVGM-urban model may be able to better characterize the nonlinear runoff generation process in cities, but for the runoff calculation of low-impact development models, the single green roof in TVGM-urban is obviously insufficient, so the model needs to be expanded with more LID facility calculation modules before it can be used.

[0029] In summary, the simplified empirical formula calculation method has unclear definitions of the control optimization objectives and has low calculation accuracy; while the stormwater model calculation method simply divides the underlying surface types into permeable areas and impermeable areas in the runoff generation part, resulting in inaccurate runoff calculations, and the stormwater model calculation method is highly dependent on data.

[0030] Based on this, the embodiment of the present application provides a multi-objective design method and equipment for a rainwater storage tank based on runoff and pollution. The multi-objective design method of the embodiment of the present application is between the simplified empirical formula calculation method and the rainwater flood model calculation method. It not only has multiple clear control objectives, but also does not require a large amount of data to establish a model and simulate the runoff and pollution load of LID facilities; and through the designed preset hybrid nonlinear runoff model, the urban underlying surface types are divided in detail, and different types of sub-areas have different calculation formulas to calculate the runoff, thereby effectively improving the accuracy of the runoff calculation in the target area, improving the calculation accuracy of the target parameters of the rainwater storage tank, and reducing the dependence on data.

[0031] Figure 1 FIG. 1 is one of the flow charts of the multi-objective design method for a rainwater storage tank in an embodiment of the present application. Figure 1 As shown, the multi-objective design method for rainwater storage tanks based on runoff and pollution can include the following steps: Step 110: Obtain rainfall parameters, regional parameters, and pollutant parameters of the target area.

[0032] First, it should be noted that the target area described in the embodiment of the present application can be any catchment area where a rainwater storage tank needs to be set up. For example, the target area can be a residential area, an industrial park, a traffic corridor, etc. in a city, or it can be agricultural land, a river bank and a waterfront area, etc. In addition, the multi-objective design method for a rainwater storage tank in the embodiment of the present application is more suitable for designing a rainwater storage tank in a small area with insufficient data, such as old urban areas, villages and towns, and planned new areas that lack pipe network data.

[0033] In this embodiment, when it is necessary to design a rainwater storage tank for a target area, the rainfall parameters, regional parameters and pollutant parameters of the target area can be obtained first. Among them, the rainfall parameters may include (but are not limited to): recurrence period, total rainfall, rainfall duration, peak coefficient, calculation step length, previous rainfall, rainstorm intensity formula parameters, spatial distribution characteristics, rainfall interval time, peak rainfall intensity, etc. These rainfall parameters can be directly obtained from existing meteorological databases, hydrological and meteorological data centers, etc., or can refer to meteorological data of similar areas.

[0034] Furthermore, regional parameters refer to data related to the runoff process in the target area. It should be noted that the runoff process refers to the process in which rainfall or other forms of water input (such as snowmelt, irrigation water, etc.) is converted into runoff on the surface or underground. It can be seen that the runoff process is not only related to the climatic conditions of the target area, but also to factors such as the soil properties, topography, and vegetation coverage of the target area. Therefore, regional parameters may include (but are not limited to): soil permeability, soil depth, soil moisture, saturated hydraulic conductivity, vegetation density, slope, elevation, and regional area of ​​the target area.

[0035] In this embodiment, the regional parameters can be obtained through existing geological databases, vegetation coverage remote sensing images, hydrological system databases, NASA Earthdata, etc.

[0036] Finally, the pollutant parameters of the target area may include the concentration and source of various pollutants in the target area, and these pollutant parameters can be obtained from the database of the environmental monitoring station.

[0037] It is worth mentioning that the pollutant parameter mainly monitored in the embodiment of the present application is TSS (Total Suspended Solids). Since the change of total suspended solids is closely related to the change of other pollutants, for example, many pollutants may be adsorbed on the total suspended solids, or co-precipitate with the total suspended solids. If the total suspended solids decrease, it can be shown that these pollutants are also decreasing. Therefore, this embodiment obtains the reduction trend of total suspended solids by taking total suspended solids as the pollution control target, and further obtains the reduction trend of other pollutants based on the correlation between total suspended solids and other pollutants. In this way, the calculation can be simplified, and complex multivariate problems can be converted into single variable problems, which reduces the complexity of the calculation, and at the same time, other typical pollutant reduction rate targets can be evaluated.

[0038] Step 120: Determine the rainfall in each time period of the target area based on the rainfall parameters.

[0039] After obtaining the rainfall parameters, regional parameters and pollutant parameters of the target area, the rain type of the target area and the rainfall in each period of the target area can be further determined according to the rainfall parameters. The rainfall in each period can constitute a rain type curve.

[0040] It should be noted that the rain type refers to the time distribution, intensity change and spatial distribution characteristics of rainfall events in a certain area within a specific period of time. The curve of rainfall changes over time is the rain type curve. For example, if the rainfall intensity in a certain area is small at the beginning of the rainfall, but the rainfall intensity gradually increases with time until it reaches a maximum value at a certain point in time, and then gradually weakens, the rain type of this rainfall event in the area is a single peak type, which is usually used to describe most typical rainstorm events. Rain types also include multi-peak type, uniform type, initial flushing type, etc.

[0041] 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 specifically limited here.

[0042] In this embodiment, the currently available rain type model can be used to determine the rain type and rainfall in each time period of the target area, for example, the Chicago rain type, the Pilgrim & Cordery rain type, the Huff rain type, the triangular rain type, etc. In this embodiment, the Chicago rain type is preferably selected to determine the rainfall in each time period. Specifically, the rainfall parameters can be input into the Chicago rain type, which will output the rain type and rainfall in each time period, and a rain intensity map can also be drawn to analyze the rain intensity distribution.

[0043] Step 130: Determine the total runoff volume of the target area in each period by using a preset hybrid nonlinear runoff model based on the rainfall in each period and regional parameters of the target area.

[0044] Among them, the preset hybrid nonlinear runoff model includes multiple network branches, and different network branches are used to calculate the runoff of different types of sub-areas in the target area, and the types of sub-areas include at least biological retention facilities and permeable pavement.

[0045] After obtaining the rainfall in each period of the target area using the rain pattern model, the rainfall in each period and the regional parameters can be further input into the pre-set hybrid nonlinear runoff model to obtain the total runoff in each period of the target area. Finally, the total flow in each period can be determined based on the total runoff in each period.

[0046] It should be noted that the hybrid nonlinear runoff model of the embodiment of the present application 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 terms of calculating the runoff of LID facilities. Therefore, it is relatively simple and the final result is not accurate. In order to improve the accuracy of the runoff calculation results and the practicality of the runoff model, the embodiment of the present application expands and improves the TVGM-urban model.

[0047] Specifically, the preset hybrid nonlinear runoff model of this embodiment includes multiple parallel network branches, each network branch corresponds to a model formula, and different network branches are used to calculate the runoff of different types of sub-areas, and the sum of the runoff of all types of sub-areas is the total runoff of the target area. In the application process, the types of multiple sub-areas can be set according to land use, and then the target area can be divided into multiple sub-areas based on the set types, and finally the preset hybrid nonlinear runoff model is used to calculate the runoff of each sub-area.

[0048] In some embodiments, the types of sub-areas may include bare soil areas, vegetation-covered areas, building areas (specifically including impermeable roofs and green roofs), road areas (specifically including impermeable roads and permeable pavements), and bioretention facilities. In addition, the area parameters may include sub-area parameters of each type of sub-area, that is, different types of sub-areas can obtain different sub-area parameters. For example, if the sub-area is a bioretention facility, the sub-area parameters may include (but are not limited to): water level changes in the water storage surface, the height of the overflow weir, the inflow of the facility, the outflow of the drain pipe, the water level of the filter layer, etc.; if the sub-area is a permeable pavement, the sub-area parameters may include (but are not limited to): the water storage capacity of the permeable pavement and the thickness and porosity of each layer of the permeable pavement, etc.

[0049] It is worth mentioning that the existing runoff generation model may require multiple sub-region parameters of each sub-region during the calculation process, such as the area, slope, elevation, etc. of the sub-region. However, some runoff generation model formulas designed in the embodiment of the present application only require the area data of the sub-region during the calculation process, and do not require the slope, elevation and other data of the sub-region. This reduces the difficulty of data collection, saves time and financial costs, and improves the practicality of the multi-objective design method of the rainwater storage tank.

[0050] In some embodiments, the total runoff of the target area for each time period is determined using a preset hybrid nonlinear runoff model based on the rainfall and regional parameters of the target area for each time period, which may include: for any time period, inputting the parameters and rainfall of each sub-region into the corresponding network branch, obtaining the runoff of each sub-region in the time period, and determining the total runoff of the target area based on the runoff of each sub-region.

[0051] Taking a time period as an example, after obtaining the rainfall and the sub-region parameters of each sub-region, the network branches corresponding to each sub-region can be determined according to the type of each sub-region, and then the parameters of each sub-region can be input into the corresponding network branches respectively; wherein, the rainfall is selectively input according to the model formula of each network branch, and if the rainfall is a parameter of the model formula of a certain network branch, the rainfall is used as an input of the network branch. Furthermore, each network branch outputs the runoff of the corresponding sub-region respectively through calculation; after obtaining the runoff of all types of sub-regions, the runoff of all types of sub-regions is added up to obtain the total runoff of the target area in this time period.

[0052] It should be noted that in the preset hybrid nonlinear runoff model of the embodiment of the present application, the model formulas of the network branches corresponding to the impermeable roofs, green roofs, bare soil areas, vegetation-covered areas and impermeable roads can use the model formulas in the existing TVGM-urban model, which will not be repeated here. The model formulas of the bioretention facility and the permeable pavement adopt the independently designed formulas provided in the embodiment of the present application.

[0053] In some embodiments, sub-area parameters of the bioretention facility type may include the water level change of the water storage surface, 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.

[0054] The model formula for the network branch corresponding to the bioretention facility type is:

[0055] In the formula, is the runoff volume of the bioretention facility type sub-area, unit: mm; is the runoff reduction factor for the bioretention facility; is the water level change of the water storage surface during period t, unit: mm; is the height of the overflow weir; is the inflow to the bioretention facility during period t; is the outflow of the drainage pipe during period t; is the infiltration amount of the filter layer during time period t. It should be noted here that the above-mentioned water storage surface layer and filter layer refer to the water storage surface layer and filter layer of the biological retention facility, respectively.

[0056] The flow calculation formula for the biological retention facility type of this embodiment (i.e., the above-mentioned model formula) is designed with the biological retention pond as a representative, taking into account infiltration, overflow, and drainage pipe outflow, so as to be able to well simulate the temporal dynamic changes of the flow generation process of the biological retention facility.

[0057] When the rainfall exceeds the maximum water storage capacity of the bioretention facility, or the rainfall intensity is greater than the surface infiltration rate, the bioretention facility may overflow. The overflow volume includes the overflow volume from the surface layer into the overflow port and the discharge volume of the drain pipe. In the model formula corresponding to the bioretention facility type, the infiltration volume of the filter layer is applied with the Darcy equation, and within the time step, the water storage volume of the water storage surface layer can not exceed the infiltration volume, and the infiltrated water cannot exceed the available volume of the filter layer. The calculation formula of the infiltration volume of the filter layer is as follows:

[0058] In the formula, The maximum permissible water level of the filter layer, unit: mm; The water level of the filter layer during the period t-1, unit: mm; is the water level change of the water storage surface during the period t-1, unit: mm; is the average bottom area of ​​the bioretention facility, unit: m 2 ; is the average porosity of the filter layer; Δt represents the unit time. Among them, the unsaturated coefficient The expression is:

[0059] In the formula, K s is the saturated hydraulic conductivity, unit: m / s; K is the unsaturated hydraulic conductivity, unit: m / s; m is the shape parameter of the medium soil.

[0060] Therefore, by inputting the sub-area parameters of the bioretention facility type sub-area into the above model formula, the runoff volume of the sub-area can be obtained.

[0061] In some embodiments, the sub-region parameters of the permeable pavement type may include the water storage capacity of the permeable pavement, the proportion of the sub-region area of ​​the bare soil area type to the total area of ​​the target area, and the thickness and porosity of each layer of the permeable pavement. The permeable pavement includes a surface layer, a leveling layer, a cushion layer, and a base layer.

[0062] The model formula for the network branch corresponding to the permeable pavement type is:

[0063] In the formula, The runoff volume for the sub-area of ​​the permeable pavement type; is the rainfall in period t; is the runoff reduction coefficient of permeable pavement; W(t) is the water storage capacity of the permeable pavement type sub-area in period t; W is the ratio of the bare soil sub-region area to the total target area; p The water capacity of the pavement layer of permeable pavement.

[0064] In this embodiment, the water capacity of the permeable pavement layer is W p It can be calculated by the following formula:

[0065] In the formula, is the surface layer thickness; is the surface layer porosity; is the thickness of the leveling layer; The porosity of the leveling layer; is the cushion thickness; is the porosity of the cushion layer; is the thickness of the base layer; is the porosity of the base layer.

[0066] The flow calculation formula for the permeable pavement type of this embodiment (i.e., the model formula corresponding to the permeable pavement type described above) takes into account the water capacity, the confluence area, and the outflow of the drainage pipe when designing, and regards each layer of the permeable pavement as a pavement structure. It should be noted that the flow calculation formula for the permeable pavement type of this embodiment does not take into account the impact of evaporation.

[0067] Finally, the total runoff R of the target area can be calculated by the following formula:

[0068] In the formula, The runoff volume for the sub-area of ​​impervious roof type; is the runoff volume of the green roof type sub-area; is the runoff volume for the sub-area of ​​the impervious road type; is the runoff volume of the bare soil area type sub-area; is the runoff volume of the sub-area of ​​the vegetation cover area type; The runoff volume for the sub-area of ​​the bioretention facility type; The runoff volume for the sub-area with permeable pavement type.

[0069] It should be noted that in the model formula of the permeable pavement type and the model formula of the biological retention facility type, in addition to the parameter of rainfall, the parameters that need to be input include the ratio of each part area to the total area of ​​the target area, the catchment area of ​​the biological retention facility, the total thickness of the surface layer, the total thickness of the filtration layer, the average bottom area of ​​the water storage surface layer, the height of the drainage pipe orifice, and the maximum water capacity of the pavement layer; the remaining parameters can be obtained through actual flow calibration. Actual flow calibration refers to the process of determining the difference between the actual flow and the theoretical flow through a series of measurements and calculations, and making adjustments. Figure 2 It is a schematic diagram of the flow generation model framework of the nonlinear time-varying process of the embodiment of the present application. Figure 2 P&C 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 the figure is the vegetation coverage area described in this embodiment, and the storage tank is the rainwater storage tank described in this embodiment. Figure 2 As shown, this embodiment divides the sub-areas in the target area into five types, namely, building area, road area, bioretention facility, bare soil area and vegetation covered area. After the target area rains, the rainwater first passes through these types of sub-areas to form runoff. The flow of the sub-area can be further obtained by the runoff of these sub-areas. Specifically, the flow can be obtained by dividing the runoff in a time period by the length of the time period.

[0070] Step 140: Determine the pollution load of the target area at each time period based on the total runoff volume and pollutant parameters of the target area at each time period.

[0071] Specifically, after obtaining the total runoff of the target area in each time period, the total runoff of each time period can be used to calculate the flow of each time period; and then the pollution load of the target area in each time period can be calculated based on the flow and pollutant parameters of each time period.

[0072] Continue to refer Figure 2 It is understandable that when rainwater washes each sub-area, the pollutants on the surface of each sub-area will flow to the drainage pipe along with the runoff. As an example, the underlying surface of the building community may contain heavy metal pollutants. When washed by rainwater, the heavy metal pollutants will flow to the drainage pipe along with the runoff. As another example, the green space may contain pesticides, fertilizers, etc. When rainwater washes the underlying surface of the green space, the pollutants in the soil will also flow to the drainage pipe along with the runoff.

[0073] In addition, usually, at the beginning of rainfall, the concentration of pollutants carried by rainwater may be high, and after a period of rainwater washing (i.e., reaching the middle and late stages of rainfall), the concentration of pollutants carried by rainwater will decrease. Based on this, the embodiment of the present application specifically determines the pollution load of the target area in the following manner.

[0074] In some embodiments, the pollutant parameters include early pollutant parameters and mid- to late-stage pollutant parameters. Figure 3 This is the second flow chart of the multi-objective design method for a rainwater storage tank in the embodiment of the present application. Figure 3 As shown, step 140 determines the pollution load of the target area in each period based on the total runoff volume and pollutant parameters of the target area in each period, which may include the following steps: Step 310: Obtain initial drop flow parameters of the target area.

[0075] Step 320: Divide the rainfall events in the target area into an early rainfall period and a middle and late rainfall period based on the initial abandonment parameters.

[0076] Step 330: For any time period, if it is determined that the time period is in the initial rainfall period based on the abandonment parameters of the time period, the pollution load of the time period is determined based on the total runoff volume and the initial pollutant parameters of the time period.

[0077] Step 340: For any time period, if the time period is determined to be in the middle and late stages of rainfall based on the abandonment parameters of the time period, the pollution load of the time period is determined based on the total runoff volume and the middle and late stage pollutant parameters of the time period.

[0078] It should be noted that the initial abandoned flow parameter may be the initial abandoned flow millimeter, the initial abandoned flow duration or the initial abandoned flow concentration, and any one of these three parameters may be selected. In the present embodiment, the initial abandoned flow millimeter may be preferentially selected as the initial abandoned flow parameter, because the initial abandoned flow millimeter is relatively easy to obtain and is relatively accurate for distinguishing the initial stage from the middle and late stages. The following takes the initial abandoned flow millimeter as an example to describe steps 310 to 340 in detail.

[0079] Considering that there is a big difference between the pollutant concentration in the runoff at the initial stage of rainfall and the pollutant concentration in the runoff at the middle and late stages of rainfall, this embodiment uses the number of millimeters of initial abandoned flow as the boundary to divide the rainfall events in the target area into the initial stage of rainfall and the middle and late stages of rainfall. The pollution load calculated in this way can not only reflect the pollution effect at the initial stage of rainfall, but also reflect the middle and late stages of rainfall effects in some sub-areas to a certain extent.

[0080] Specifically, by obtaining the number of millimeters of abandoned flow in each period, it is possible to first determine whether the current period is in the early stage of rainfall or in the middle and late stages of rainfall. If the number of millimeters of abandoned flow in this period is less than the number of millimeters of abandoned flow in the early stage, it is determined that the period is in the early stage of rainfall. At this time, the total runoff and initial pollution parameters of this period can be used to determine the pollution load of this period. If the number of millimeters of abandoned flow in this period is greater than or equal to the number of millimeters of abandoned flow in the early stage, it is determined that the period is in the middle and late stages of rainfall. At this time, the total runoff and middle and late pollution parameters of this period can be used to determine the pollution load of this period.

[0081] Since the pollutant concentrations in the same period are similar, in this embodiment, the median or average of all pollutant concentrations in the initial stage of rainfall can be selected as the initial pollutant parameter, and similarly, the median or average of all pollutant concentrations in the middle and late stages of rainfall can be selected as the middle and late stage pollutant parameter. By generalizing the initial pollutant parameters and the middle and late stage pollutant parameters, only a small amount of pollutant concentration data can be obtained to calculate the pollution load, and the entire pollution load calculation process can be simplified, thereby further reducing the complexity of the design process while ensuring the accuracy of the calculation results, and improving the practicality of the multi-objective design method for rainwater storage tanks.

[0082] In this embodiment, the calculation formula of the pollution load can be specifically expressed as:

[0083] In the formula, is the pollution load in period t; is the flow rate in period t; is the initial pollutant concentration, unit: mg / L; is the pollutant concentration in the middle and late stages, unit: mg / L; is the initial abandoned flow in millimeters, unit: mm; β is the abandoned flow in millimeters during period t.

[0084] In actual application, when the number of millimeters of abandoned flow β in period t is less than the number of millimeters of initial abandoned flow, the flow rate in period t can be substituted into the first formula to calculate the pollution load; when the number of millimeters of abandoned flow β in period t is greater than or equal to the number of millimeters of initial abandoned flow, the flow rate in period t can be substituted into the second formula to calculate the pollution load.

[0085] Therefore, the pollution load calculation method designed in the embodiment of the present application not only takes into account the initial pollution effect and the mid- and late-stage pollution effects respectively, making the final pollution load calculation result more accurate, but also simplifies the entire calculation process by generalizing parameters, thereby improving the operating efficiency of the multi-objective design of the rainwater storage tank.

[0086] Step 150: Based on the total runoff and pollution load of the target area in each period, and with the goal of reducing peak flow, controlling non-point source pollution, or controlling water quality and water quantity balance, determine the target parameters of the rainwater storage tank corresponding to the target area.

[0087] After obtaining the total runoff and pollution load in each period of the target area, the target parameters of the rainwater storage tank corresponding to the target area can be determined based on the total runoff and pollution load in each period with the goal of reducing peak flow, controlling surface source pollution or balancing water quality and quantity.

[0088] It should be noted here that the specific factor to be used as the control target can be determined based on the underlying surface type of the target area, or it can be selected by the staff based on actual needs. For example, if the target area is an industrial park and the industrial pollution in the industrial park is relatively serious, you can choose to control non-point source pollution as the target, or you can choose to balance water quality and water quantity as the target. If the target area is a park, you can choose to reduce peak flow as the target, or you can choose to balance water quality and water quantity as the target.

[0089] In some embodiments, step 150 determines the target parameters of the rainwater storage tank corresponding to the target area based on the total runoff and pollution load in each time period of the target area, and with the goal of reducing peak flow, controlling non-point source pollution, or controlling water quality and water quantity balance. It may include: determining the inflow process line based on the total runoff in each time period of the target area, and determining the pollution load process line based on the pollution load in each time period of the target area; determining the target parameters of the rainwater storage tank corresponding to the target area based on the inflow process line, and with the goal of reducing peak flow, or, determining the target parameters of the rainwater storage tank corresponding to the target area based on the pollution load process line, and with the goal of controlling non-point source pollution, or, determining the target parameters of the rainwater storage tank corresponding to the target area based on the inflow process line and the pollution load process line, and with the goal of controlling water quality and water quantity balance.

[0090] The embodiment of the present application provides a rainwater storage tank design method under three objectives, and can adapt to different design objectives without modeling, and quickly and accurately obtain the target parameters of the rainwater storage tank. It should be noted here that the target parameters of the rainwater storage tank may include (but are not limited to): the volume of the rainwater storage tank, the height of the storage tank, the position of the orifice, etc.

[0091] Specifically, after obtaining the total runoff and pollution load of the target area in each period, the inflow process line can be obtained based on the total runoff of the target area in each period. The inflow process line is a curve used to describe the change of water flow over time in a specific time period during the confluence process. Furthermore, the pollution load process line can be determined based on the pollution load of the target area in each period. The pollution load process line is a curve used to describe the change of pollutants over time in a specific time period.

[0092] It is worth mentioning that the present embodiment only requires an inflow process line because the target area of ​​the present embodiment is a small area, and therefore, a confluence process line is not required. Specifically, the ideal application area of ​​the present application embodiment is a small area, so in the process of converting the rainfall process line to the inflow process line, rainfall losses such as evaporation are ignored, and the runoff process is taken as the inflow process. Secondly, due to the complexity of the urban pipe network system, traditional pipe network confluence models such as the dynamic wave method, the stable wave method, and the motion wave method, including the equivalent drainage model in the TVGM-urban model, all have problems such as a large number of input parameters. The input of the parameters has great uncertainty and requires actual data calibration (i.e., calibration and calibration of the data). However, in actual applications, the actual measured data of the pipe network outlet flow is usually difficult to obtain, and the actual data will also be greatly disturbed by the real environment, resulting in a weakened reference. Furthermore, the more model parameters there are, the more complex the model will be, reducing the applicability of the model. Therefore, the model in the embodiment of the present application ignores the confluence part. According to some studies, in the calculation of the volume of the storage tank, the inflow hysteresis caused by the confluence time does not have a great impact on the calculation of the capacity. In a small area, the runoff process can be directly converted into the inflow flow process.

[0093] Figure 4 (a) is a schematic diagram of an inflow process line of a specific embodiment of the present application. The inflow process line described in the embodiment of the present application can refer to Figure 4 (a). Figure 4 (b) is a schematic diagram of a pollution load process line of a specific embodiment of the present application. The pollution load process line described in the embodiment of the present application can refer to Figure 4 (b).

[0094] After determining the inflow process line and the pollution load process line, 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 process line and with the goal of reducing peak flow. The second way is to determine the target parameters of the rainwater storage tank corresponding to the target area based on the pollution load process line and with the goal of controlling non-point source pollution. The third way is to determine the target parameters of the rainwater storage tank corresponding to the target area based on the inflow process line and the pollution load process line and with the goal of controlling water quality and water quantity balance.

[0095] The above three methods are introduced in detail below.

[0096] In some embodiments, the first method, based on the inflow process line, determines the target parameters of the rainwater storage tank corresponding to the target area with the goal of reducing the peak flow, which may include: taking the downstream design flow of the rainwater storage tank as the control standard, and determining the first time and the second time based on the inflow process line; using a preset first volume formula and determining the first effective volume based on the first time and the second time, and determining the target parameters of the rainwater storage tank corresponding to the target area based on the first effective volume.

[0097] In this embodiment, the storage tank volume calculation method with the goal of reducing peak flow mainly uses the downstream design flow as the control standard, and calculates with the peak reduction amount, peak reduction rate and total runoff control rate as evaluation indicators.

[0098] Figure 5 FIG. 1 is a schematic diagram of an inflow process line and a downstream design flow rate of a specific embodiment of the present application. Figure 5 As shown, Figure 5 The vertical axis Q represents the flow rate, and the horizontal axis T represents the time. Figure 5 The horizontal line in represents the downstream design flow, and the area enclosed above the horizontal line and below the inflow process line is the volume required to reduce the peak flow, that is, the first effective volume V1 of the storage tank. The horizontal coordinates of the two intersections of the horizontal line representing the downstream design flow and the inflow process line are the first time and the second time respectively. The preset first volume formula for reducing peak flow is as follows:

[0099] In the formula, The first effective volume calculated with the goal of reducing peak flow; is the inflow process line; is the downstream design flow; a is the time corresponding to the first intersection of the horizontal line representing the downstream design flow and the inflow process line (i.e. the first time); b is the time corresponding to the second intersection of the horizontal line representing the downstream design flow and the inflow process line (i.e. the second time).

[0100] After obtaining the first effective volume, the bottom area of ​​the regulating reservoir can be designed according to the specifications of the target area, and the final regulating reservoir volume, regulating reservoir height and orifice position can be calculated based on the first effective volume and the bottom area of ​​the regulating reservoir. This calculation assumes that the downstream is gravity outflow by default. The calculation methods of the regulating reservoir in the model are all developed based on the advanced method of total runoff control, including downstream design flow and regulating reservoir control effect indicators.

[0101] Therefore, the method of calculating the volume of the regulating reservoir in this embodiment with the goal of reducing peak flow can accurately grasp the peak reduction position and the reduced peak flow. Compared with the total runoff control of the traditional calculation method, the calculation result is more accurate and greatly reduces the effective volume of the regulating reservoir.

[0102] In some embodiments, the second method, based on the pollution load process line, determines the target parameters of the rainwater storage tank corresponding to the target area with the goal of controlling surface source pollution, which may 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 process line; using a preset second volume formula to determine the second effective volume 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.

[0103] In this embodiment, the volume calculation method of the regulating and storage tank with the goal of controlling non-point source pollution is mainly calculated based on the pollution control rate of the rainwater regulating and storage tank as the control standard. Among them, the sedimentation process provides two methods, the first-order decay equation and the Stokes formula, for calculating the retention time. In the rainwater regulating and storage tank, the sedimentation of polluted particles is very important for water purification, and the pollution concentration characteristics in different regions are different, and the time required for sedimentation is also different. The retention time is mainly solved by the type, concentration and water quality treatment requirements of the pollutants in the regulating and storage tank, and its calculation is closely related to parameters such as the volume of the regulating and storage tank. The decay constant and initial pollutant concentration in the first-order decay equation reflect the decay of pollutants in the regulating and storage tank. Affected by the volume of the regulating and storage tank, the larger the volume, the larger the decay constant. When the current pollution concentration in the pool is precipitated and decayed to meet the outflow concentration standard, it is the retention 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 type and concentration of pollutants in the pool. The above parameters can be used to obtain the sedimentation velocity of pollutant particles in the pool, and then the sedimentation height can be calculated based on the pool area parameters. The sedimentation time is then the sedimentation height / settlement velocity.

[0104] Figure 6 FIG. 1 is a schematic diagram of a pollution load process line and a pollution control rate of a specific embodiment of the present application. Figure 6 As shown, Figure 6 The vertical axis Q represents the flow rate, and the horizontal axis T represents the time. Figure 6 The vertical line in is the pollution control rate, and the area to the left of the vertical line, to the right of the pollution load process line, and the horizontal axis of the coordinate system is the second effective volume V2 of the rainwater storage tank. The horizontal coordinate of the intersection of the vertical line representing the pollution control rate and the pollution load process line is the third time. The preset second volume formula for controlling nonpoint source pollution is as follows:

[0105] In the formula, It is the second effective volume calculated for the purpose of controlling nonpoint source pollution; is the inflow process line; c is the time corresponding to when the pollution load reaches the pollution control rate (i.e., the third time). It should be noted that the third time c can be determined in advance based on the intersection of the pollution load process line and the pollution control rate, and is directly substituted here.

[0106] Similarly, after obtaining the second effective volume, the bottom area of ​​the reservoir can also be designed according to the specifications of the target area, and the final reservoir volume, reservoir height and orifice position can be calculated based on the second effective volume and the bottom area of ​​the reservoir, which will not be repeated here.

[0107] Therefore, the method of calculating the volume of the regulating reservoir in this embodiment, which aims to control surface source pollution, takes into account the pollution load in the middle and late stages, and adopts the pollution control rate position cut-off to achieve all pollution. Therefore, it can also be applied to certain areas with late flushing effects.

[0108] In some embodiments, a third method, based on the inflow process line and the pollution load process line, and with the goal of water quality and water quantity balance control, determines the target parameters of the rainwater storage tank corresponding to the target area, which may include: taking the peak flow reduction rate of the rainwater storage tank as the control standard, and determining the first time and the second time based on the inflow process line, and determining the first effective volume 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, and determining the third time based on the pollution load process line, and determining the second effective volume using the preset second volume formula and 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.

[0109] In this embodiment, water quality and water quantity are mainly controlled targets, among which water quantity is controlled by peak flow reduction rate, while water quality is still controlled by pollution control rate. The downstream design flow and total runoff control rate are used as evaluation indicators to jointly determine the volume of the rainwater storage tank.

[0110] Figure 7 Schematic diagram of peak flow reduction rate and pollution control rate of a specific embodiment of the present application. It should be noted that for the sake of clarity, Figure 7 The inflow process line and the pollution load process line are represented by the same curve. Figure 7 As shown, Figure 7 The vertical axis Q represents the flow rate, and the horizontal axis T represents the time; if Figure 7 The curve in is the inflow process line, then Figure 7 The horizontal line in is the peak flow reduction rate, and the area enclosed above the horizontal line and below the inflow process line is the volume required to reduce the peak flow, that is, the first effective volume V1 of the storage tank. The horizontal coordinates of the two intersections of the horizontal line representing the downstream design flow and the inflow process line are the first time and the second time, respectively. Specifically, a first effective volume V1 can be determined using the above-mentioned preset first volume formula, the first time and the second time. The calculation process can refer to the process of the aforementioned embodiment, which will not be repeated here.

[0111] Continue to refer Figure 7 ,like Figure 7 The curve in is the pollution load process line, then Figure 7The vertical line in is the pollution control rate, the area enclosed by the left of the vertical line, the right of the pollution load process line 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 of the vertical line representing the pollution control rate and the pollution load process line is the third time. Specifically, a second effective volume V2 can be determined using the above-mentioned preset second volume formula and the third time. The calculation process can refer to the process of the aforementioned embodiment, which will not be repeated here.

[0112] 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:

[0113] Similarly, after obtaining the second effective volume, the bottom area of ​​the reservoir can also be designed according to the specifications of the target area, and the final reservoir volume, reservoir height and orifice position can be calculated based on the second effective volume and the bottom area of ​​the reservoir, which will not be repeated here.

[0114] Therefore, the method for calculating the volume of the regulating storage tank in this embodiment, which aims at controlling the balance of water quality and quantity, adopts the dual indicators of peak flow reduction rate and pollution control rate for calculation, which can simultaneously meet the requirements of reducing peak flow and controlling runoff pollution, thereby making the calculation results of the target parameters of the rainwater regulating storage tank more accurate and reasonable.

[0115] It is worth mentioning that the multi-objective design method for rainwater storage tanks based on runoff and pollution in the embodiment of the present application can be implemented using EXCEL and Python programs. Specifically, the rainfall parameters, regional parameters, and pollutant parameters of the target area can all be input into an EXCEL file, and then the multi-objective design method for rainwater storage tanks in this embodiment can be converted into an application program through the Python language. During the execution of the application program, the required data can be directly retrieved from the EXCEL file, and the final execution result of the application program (i.e., the target parameters of the rainwater storage tank under the three objectives) can also be output to the EXCEL file for display. Thus, without the need to build a model and simulate LID facilities, data such as rainfall, runoff, pollution load, storage tank configuration parameters, and benefit indicators can be obtained quickly and accurately to assist in the refined design of rainwater storage tanks in sponge city construction.

[0116] The following is a specific example to further illustrate the Python program implementation process.

[0117] First, enter the rainfall parameters, regional parameters, and pollutant parameters of the target area in Excel; after entering the parameters, make sure Excel remains closed before running the Python application. The current input table is named "Reservoir Calculation.xlsx". After running the code, the results will be automatically saved in a new Excel and named "Reservoir Calculation_output.xlsx". The new file will maintain the interface of the original table. The changes will also be made in the output table. If the file path or naming needs to be changed accordingly, the naming in the Python code needs to be changed. It is recommended that the input parameter table should not be shared with the result output table, which may easily cause irreversible file damage. The application runs in four stages, which are explained below: First, input the original data of the target area. You can directly enter the specified parameters in Excel. The first stage of automatic calculation of the storage tank is to design the rain pattern. After closing the Excel file of input parameters, run the "Chicagorainfall.py" file to complete the calculation. The file results are displayed in "storage tank calculation_output.py", which can be opened for inspection.

[0118] The second stage of automatic calculation of storage and regulation is to calculate the flow rate of the target area. The actual flow rate and the previous rainfall influencing the flow rate need to be input for calibration verification. After calibration verification, the calculation can be performed normally. Close the "storage pool calculation_output.py" file and run the "rainoff.py" file.

[0119] The third stage of automatic calculation of the storage tank is to calculate the pollution load of the target area and the inflow process line of the storage tank. Close the "storage tank calculation_output.py" file and run the "pollution load.py" file.

[0120] The fourth stage of automatic calculation of storage is the calculation of storage tank volume. Volume calculation includes three modules: peak flow reduction type, surface source pollution control type, and comprehensive control type. Users can choose the calculation according to their needs. Close the "storage tank calculation_output.py" file, run the "detention tank volume-peak flowreduction.py" file to reduce peak flow, run the "detention tank volume-pollutionreduction.py" file to control surface source pollution, or run the "detention tank volume-combined.py" file to run comprehensive control.

[0121] Users 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 current path of the new Excel file, with the suffix "_output". Users can change it in the code according to their needs, and the output file is displayed in the original table.

[0122] Therefore, the multi-objective design method of the rainwater storage tank in the embodiment of the present application simplifies the calculation model NTVP-SDT and provides a more refined and simple method for calculating the storage tank volume. The nonlinear rainfall runoff response of various land use types on the urban surface, the pollutant concentration flushing process and indicator correlation of rainfall events, and the differences in the calculated storage tank volume under three different objectives are taken into account. The embodiment of the present application has the following advantages: (1) The flow generation calculation method based on the nonlinear process provided in the embodiment of the present application requires fewer parameters, has a higher accuracy of the calculation results, and has high computational efficiency. Compared with the commonly used SWMM model, it can better describe the nonlinear process of flow generation and obtain more refined results, and does not require a large amount of data modeling such as pipeline network geology, so it is low-cost and easy to use.

[0123] (2) The two-stage pollution load calculation method provided in the embodiment of the present application greatly simplifies the calculation process, effectively avoids the deficiencies in water quality monitoring, and has a simple structure and is easy to calculate.

[0124] (3) The embodiment of the present application is made into a segmented application through the independently developed rainfall, runoff, pollution, and storage tank calculation methods, and each module of the application can be used separately or as a whole to calculate the target parameters of the storage tank. The structure between the application modules is clear and easy to optimize and improve. And through the design of the storage tank under three objectives, targeted design can be achieved. Compared with the commonly used empirical formula, it is simple to calculate and effectively avoids over-design; compared with the rain and flood model, it does not require iterative calculation or modeling, which ensures the calculation accuracy while greatly improving the calculation speed.

[0125] Figure 8 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 8As shown, the electronic device may 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 communicate with each other via the communication bus 840 . The processor 810 can call the logic instructions in the memory 830 to execute a multi-objective design method for a rainwater storage tank based on runoff and pollution, including: obtaining rainfall parameters, regional parameters and pollutant parameters of the target area; determining the rainfall in each time period of the target area based on the rainfall parameters; using a preset hybrid nonlinear runoff generation model and based on the rainfall and regional parameters in each time period of the target area, determining the total runoff in each time period of the target area; wherein the preset hybrid nonlinear runoff generation model includes multiple network branches, and different network branches are used to calculate the runoff of different types of sub-areas in the target area, and the types of sub-areas include at least biological retention facilities and permeable pavement; determining the pollution load in each time period of the target area based on the total runoff and pollutant parameters in each time period of the target area; determining the target parameters of the rainwater storage tank corresponding to the target area based on the total runoff and pollution load in each time period of the target area, and with the goal of reducing peak flow, controlling surface source pollution or controlling water quality and water quantity balance.

[0126] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0127] On the basis of the above embodiments, on the other hand, the present invention also provides a computer program product, which includes a computer program, which can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the multi-objective design method of rainwater storage tank based on runoff and pollution provided by the above methods, including: obtaining rainfall parameters, regional parameters and pollutant parameters of the target area; determining the rainfall in each time period of the target area based on the rainfall parameters; using a preset hybrid nonlinear runoff generation model and based on the rainfall and regional parameters in each time period of the target area, determining the total runoff in each time period of the target area; wherein the preset hybrid nonlinear runoff generation model includes multiple network branches, and different network branches are used to calculate the runoff of different types of sub-areas in the target area, and the types of sub-areas include at least biological retention facilities and permeable pavement; determining the pollution load in each time period of the target area based on the total runoff and pollutant parameters of the target area; determining the target parameters of the rainwater storage tank corresponding to the target area based on the total runoff and pollution load in each time period of the target area, and with the goal of reducing peak flow, controlling surface source pollution or controlling water quality and water quantity balance.

[0128] On the basis of the above embodiments, on another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the multi-objective design method for a rainwater storage tank based on runoff and pollution provided by the above methods, including: obtaining rainfall parameters, regional parameters and pollutant parameters of a target area; determining the rainfall in each time period of the target area based on the rainfall parameters; determining the total runoff in each time period of the target area based on the rainfall and regional parameters in each time period of the target area using a preset hybrid nonlinear runoff generation model; wherein the preset hybrid nonlinear runoff generation model includes multiple network branches, and different network branches are used to calculate the runoff of different types of sub-areas in the target area, respectively, and the types of sub-areas include at least biological retention facilities and permeable pavement; determining the pollution load in each time period of the target area based on the total runoff and pollutant parameters in each time period of the target area; determining the target parameters of the rainwater storage tank corresponding to the target area based on the total runoff and pollution load in each time period of the target area, and with the goal of reducing peak flow, controlling surface source pollution or controlling water quality and water quantity balance.

[0129] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0130] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art 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 ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to 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 of the target area; Determine the rainfall in each time period of the target area based on the rainfall parameter; Determine the total runoff volume of the target area in each period of time by using a preset hybrid nonlinear runoff generation model and based on the rainfall in each period of time of the target area and the regional parameters; wherein the preset hybrid nonlinear runoff generation model includes a plurality of network branches, and different network branches are used to calculate the runoff volume of different types of sub-areas in the target area, and the types of the sub-areas include at least bioretention facilities and permeable pavement; Determine the pollution load of the target area at each time period based on the total runoff volume of the target area at each time period and the pollutant parameter; Based on the total runoff and pollution load in each time period of the target area, and with the goal of reducing peak flow, controlling surface source pollution or controlling water quality and water quantity balance, the target parameters of the rainwater storage tank corresponding to the target area are determined.

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

3. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 2 is characterized in that: The sub-area 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 of the bioretention facility and the outflow of the drainage pipe; The model formula for the network branch corresponding to the bioretention facility is: In the formula, is the runoff volume of the sub-area of ​​the bioretention facility; is the runoff reduction factor for the bioretention facility; is the water level change of the water storage surface during period t; is the height of the overflow weir; is the inflow to the bioretention facility during period t; is the outflow of the drainage pipe during period t; is the infiltration amount of the filter layer during period t.

4. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 2 is characterized in that: The sub-region parameters of the permeable pavement at least include water storage capacity and the proportion of the sub-region area of ​​the bare soil area to the total area of ​​the target area; The model formula of the network branch corresponding to the permeable pavement is: In the formula, is the runoff volume of the permeable pavement sub-area; is the rainfall in period t; is the runoff reduction coefficient of the permeable pavement; W(t) is the water storage capacity of the permeable pavement sub-area in time period t; W is the ratio of the sub-region area of ​​the bare soil region to the total area of ​​the target region; p The water capacity of the pavement layer of permeable pavement.

5. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 1 is characterized in that: The pollutant parameters include initial pollutant parameters and mid- to late-stage pollutant parameters. The determining of the pollution load of the target area in each period based on the total runoff volume of the target area in each period and the pollutant parameters includes: Acquire initial abandoned flow parameters of the target area; Dividing the rainfall events in the target area into an early rainfall stage and a middle and late rainfall stage based on the initial abandonment parameters; For any time period, if it is determined that the time period is in the initial stage of rainfall based on the abandoned flow parameters of the time period, the pollution load of the time period is determined based on the total runoff volume of the time period and the initial pollutant parameters; For any time period, if it is determined that the time period is in the middle and late stages of the rainfall based on the abandonment parameters of the time period, the pollution load of the time period is determined based on the total runoff volume of the time period and the middle and late stage pollutant parameters.

6. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 1 is characterized in that: The target parameters of the rainwater storage tank corresponding to the target area are determined based on the total runoff and pollution load of the target area in each period, with the goal of reducing peak flow, controlling surface source pollution or balancing water quality and water quantity, including: Determine an inflow process line based on the total runoff volume of the target area in each time period, and determine a pollution load process line based on the pollution load of the target area in 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 surface 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 controlling water quality and water quantity balance.

7. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 6 is characterized in that: The target parameters of the rainwater storage tank corresponding to the target area are determined based on the inflow process line and with the goal of reducing peak flow, including: Taking the downstream design flow of the rainwater storage tank as a control standard, and determining the first time and the second time based on the inflow process line; A first effective volume is determined based on the first time and the second time using a preset first volume formula, and a target parameter of a rainwater storage tank corresponding to the target area is determined based on the first effective volume.

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

9. The multi-objective design method for rainwater storage tanks based on runoff and pollution according to claim 6 is characterized in that: The target parameters of the rainwater storage tank corresponding to the target area are determined based on the inflow process line and the pollution load process line and with the goal of water quality and water quantity balance control, including: Taking the peak flow reduction rate of the rainwater storage tank as a control standard, determining a first time and a second time based on the inflow process line, 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, determining a third time based on the pollution load process line, and determining a second effective volume using a preset second volume formula and the third time; A maximum value is selected from the first effective volume and the second effective volume, and a target parameter of the rainwater storage tank corresponding to the target area is determined based on the maximum value.

10. An electronic device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the computer program, the multi-objective design method for a rainwater storage tank based on runoff and pollution is implemented as described in any one of claims 1 to 9.

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