Method and system for determining scale of first rain storage pond based on rainfall session interception rate

Abstract

The invention provides a method and system for determining the scale of an initial rain regulation and storage pond based on the rainfall session interception rate. The method comprises the following specific steps: screening out typical annual 5-minute step rainfall data; the method comprises the following steps: establishing a relation curve of rainfall capacity and a closure rainfall accumulated session frequency difference value, selecting an inflection point of the curve, and determining the rainfall capacity corresponding to the inflection point as a closure standard recommended value; according to typical annual 5-minute step rainfall data, typical session rainfall with representativeness is screened to serve as design rainfall; constructing a numerical model of the drainage network of the research area; simulating water catchment time t1 required for collecting all initial rainwater; and obtaining the design scale of the first rain storage pond. The technical defects existing in existing first rain storage pond scale argumentation are overcome, and the reasonability of first rain storage pond scale argumentation is improved.

Description

Technical Field

[0001] The present application relates to the field of water environment management, and specifically to a method and system for determining the scale of an initial rain storage pool based on the interception rate of rainfall events. Background Art

[0002] In the urban water pollution control, the pollution of urban water system by first rain has been paid more and more attention. As an effective measure to control the pollution of first rain in cities, the first rain storage pond has been widely used at home and abroad for its good interception effect.

[0003] The scale of the first rain storage tank directly affects the effect of pollution load reduction. Under certain conditions, the scale of the storage tank is proportional to the amount of pollution reduction, but inversely proportional to the project investment, that is, there is a conflict and contradiction between the project effect and the project investment. Europe generally calculates the scale of the first rain storage tank according to the impervious surface and rainfall; Germany uses the area load method to determine the amount of rainwater to be stored per unit area; most domestic methods use the runoff depth method to calculate the scale of the storage tank, mainly based on the "Outdoor Drainage Design Code" (GB50014-2021) to intercept 4-8mm initial rainwater to calculate the scale of the first rain storage tank.

[0004] However, these methods are all empirical formulas without completely reliable theoretical basis. They ignore the temporal and spatial differences and uncertainties of rainfall in different regions, as well as the impact of the dynamic convergence process of initial rainwater on the scale of the storage pond. Their conclusions are not scientific enough and lack representativeness and universality.

[0005] Therefore, it is necessary to propose a new method that takes into account both engineering investment savings and engineering management effects and scientifically and rationally determines the scale of the initial rain storage pool to solve the defects of the above method. Summary of the invention

[0006] The purpose of the embodiments of the present application is to provide a method and system for determining the scale of an initial rain storage tank based on the interception rate of rainfall events, so as to solve the technical defects in the existing scale justification of initial rain storage tanks and improve the rationality of the scale justification of initial rain storage tanks.

[0007] To achieve the above objectives, this application provides the following technical solutions:

[0008] In a first aspect, an embodiment of the present application provides a method for determining the size of an initial rain storage pool based on a rainfall interception rate, comprising the following specific steps:

[0009] Step 1: Select the long series of hourly rainfall data, and filter out the 5-minute step rainfall data of typical years based on the long series rainfall data;

[0010] Step 2: Divide the long series / typical year rainfall events, sort the rainfall events from small to large according to rainfall, count the effective rainfall above 2 mm and its corresponding cumulative rainfall events, calculate the percentage of each rainfall cumulative event in the total effective rainfall events above 2 mm as the interception rainfall cumulative event frequency, analyze the interception rainfall cumulative event frequency difference corresponding to each adjacent rainfall, establish a relationship curve between rainfall and its interception rainfall cumulative event frequency difference, select the inflection point of the curve, and the rainfall corresponding to the inflection point is the interception standard recommended value;

[0011] Step 3: Based on the 5-minute step rainfall data in a typical year, select representative typical rainfall events as the design rainfall;

[0012] Step 4: Construct a numerical model of the drainage network in the study area;

[0013] Step 5: Input the initial rainwater portion corresponding to the interception standard determined in step 1 in the typical rainfall data, and simulate the water collection time t1 required for the collection of all the initial rainwater;

[0014] Step 6: Input typical rainfall data, simulate the total outflow in the first t1 period under typical rainfall conditions as the interception scale of the storage tank, consider the amount of water treated by the initial rain treatment facilities in the first t1 period, and obtain the design scale of the initial rain storage tank.

[0015] The typical year 5-minute step rainfall data selects an annual rainfall close to the multi-year average, and its temporal and spatial distribution characteristics of annual rainfall are also close to the multi-year average.

[0016] The rainfall events are continuous rainfall with an interval of not less than 2 hours, and effective rainfall is rainfall events with a rainfall of more than 2 mm. The formula for the cumulative frequency of interception rainfall events is:

[0017]

[0018] Among them, p n is the cumulative frequency of interception rainfall, n is the ranking number of interception rainfall from small to large in the effective rainfall events, and m is the total number of effective rainfall events in the long series of rainfall.

[0019] The drainage network numerical model is constructed using SWMM open source software or InfoWorks ICM, MIKE urban commercial software. The data required to construct the drainage network numerical model include but are not limited to: rainwater network data, terrain elevation data, and underlying surface data, wherein the rainwater network data includes pipe size, pipe material, upstream and downstream pipe bottom elevations, rainwater well size, well bottom elevation, and well depth.

[0020] The initial rainwater portion corresponding to the interception standard determined in step 1 in the input typical rainfall data is simulated, and the water collection time t1 required for collecting all the initial rainwater is specifically:

[0021] Draw a rainfall accumulation curve or table with a 5-minute step length for typical rainfall events. According to the initial rain interception standard determined in step 1, the rainfall process with the accumulated rainfall of typical rainfall events equal to the initial rain interception standard is used as the rainfall data of typical initial rain events to input into the model;

[0022] The model simulation calculation starts, the model output step is 5 minutes, and the moment when the terminal outflow is 0 is the confluence time t1 required for all the initial rainwater to be intercepted.

[0023] The input typical rainfall data is used to simulate the total outflow in the first t1 period under typical rainfall conditions as the interception scale of the storage tank. Considering the treated water volume of the initial rain treatment facility in the first t1 period, the design scale of the initial rain storage tank is obtained as follows:

[0024] Input the typical rainfall data obtained in step 2 into the model;

[0025] Start the model simulation calculation, the model output step is 5 minutes, and output the flow process at the end of the drainage network;

[0026] The cumulative flow from the beginning of the terminal outflow to the moment t1 is the interception scale of the initial rain storage pool;

[0027] The minimum storage capacity of the regulating reservoir is the cumulative flow before time t1 minus the total treated water volume. The equation of the flow rate changing over time is solved as follows:

[0028]

[0029] Where: V is the scale of the regulating reservoir; t is the time from the start of water inflow to the stop of water inflow; t1 is the regulating time; Q in —Rainfall terminal flow; Q out —The treatment capacity of initial rainwater treatment facilities.

[0030] In a second aspect, the embodiment of the present application provides a system for determining the size of an initial rain storage pool based on the interception rate of rainfall events, comprising:

[0031] The rainfall data selection module selects long series hourly rainfall data and filters out the 5-minute step rainfall data of typical years based on the long series rainfall data;

[0032] The interception standard recommended value calculation module divides the long series / typical year rainfall events, sorts the rainfall events from small to large according to rainfall, counts the effective rainfall above 2 mm and its corresponding cumulative rainfall events, calculates the percentage of each rainfall cumulative event in the total effective rainfall events above 2 mm as the interception rainfall cumulative event frequency, analyzes the interception rainfall cumulative event frequency difference corresponding to each adjacent rainfall, establishes a relationship curve between rainfall and its interception rainfall cumulative event frequency difference, selects the inflection point of the curve, and the rainfall corresponding to the inflection point is the interception standard recommended value;

[0033] The design rainfall screening module selects representative typical rainfall events as the design rainfall based on the 5-minute step rainfall data in a typical year;

[0034] Model building module, which builds the numerical model of the drainage network in the study area;

[0035] The water collection time calculation module inputs the initial rainwater portion corresponding to the interception standard determined in the typical rainfall data, and simulates the water collection time t1 required for all the initial rainwater to be collected;

[0036] The design scale calculation module of the first rain storage tank inputs typical rainfall data, simulates the total outflow in the first t1 period under typical rainfall conditions as the interception scale of the storage tank, and considers the treated water volume of the first rain treatment facilities in the first t1 period to obtain the design scale of the first rain storage tank.

[0037] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a program code. When the program code is executed by a processor, the steps of the method for determining the scale of an initial rain storage pool based on the interception rate of rainfall events as described above are implemented.

[0038] Compared with the prior art, the invention has the following beneficial effects: using the measured long series rainfall data, determining the interception standard of the first rain storage pool through the statistical theory method, taking into account the temporal and spatial differences and uncertainty of rainfall, the first rain interception standard obtained is more universal and reasonable;

[0039] Based on typical rainfall data, the drainage network numerical model is used to simulate and calculate the scale of the regulating storage tank, taking into account the dynamic convergence process of the initial rainwater. The scale of the regulating storage tank obtained by the commonly used empirical formula method is more scientific and reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 A flow chart of a method for determining the scale of an initial rain storage pool according to the present invention;

[0042] Figure 2 This is a schematic diagram of a method for calculating the scale of an initial rain storage pool according to the present invention;

[0043] Figure 3 This is a schematic diagram of typical annual rainfall data according to an embodiment of the present invention;

[0044] Figure 4 A demonstration diagram for determining the recommended value of the initial rainwater interception standard in an embodiment of the present invention;

[0045] Figure 5 This is a schematic diagram of typical rainfall data in an embodiment of the present invention;

[0046] Figure 6 It is a land use overview map of the project area in the embodiment of the present invention;

[0047] Figure 7 This is a generalized schematic diagram of the SWMM drainage network numerical model according to an embodiment of the present invention;

[0048] Figure 8 This is a schematic diagram of calculating the scale of a storage pool under typical rainfall conditions in an embodiment of the present invention;

[0049] Fig. 9 It is a system block diagram of the present invention. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0051] The terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0052] like Figure 1 As shown, the present invention provides a method for determining the scale of the initial rain storage pool based on the interception rate of rainfall events, and the specific implementation steps are as follows:

[0053] Step 1: Collect long-series rainfall data for the project area in the past 30 years. First, calculate the average annual rainfall and monthly average rainfall in the past 30 years. Perform deviation analysis on the annual rainfall, monthly rainfall, annual average rainfall and monthly average rainfall to select annual rainfall data with annual rainfall close to the multi-year average and monthly rainfall distribution value close to the multi-year average as typical annual rainfall data. This time, the rainfall data of 2012 was selected as the typical annual rainfall data of the project area.

[0054] Step 2: Based on the 5-minute step rainfall data of a typical year, the interception rate of rainfall events is used to determine the initial rain interception standard in the project area. The specific process is as follows:

[0055] (1) Rainfall events were divided according to the 5-minute step rainfall data in 2012, a typical year. The principle of division is that rainfall within a rainfall interval of less than 2 hours is regarded as one rainfall event. In the typical year of the project area, a total of 146 effective rainfall events with a rainfall of more than 2 mm were divided, such as Figure 3 As shown;

[0056] (2) The 146 effective rainfall events in a typical year were sorted from small to large according to rainfall amount, and the percentage of each rainfall amount accumulated in the total effective rainfall events above 2 mm was calculated as the interception rainfall accumulated event frequency. The difference in the interception rainfall accumulated event frequency corresponding to each adjacent rainfall amount was analyzed. Table 1 shows the rainfall accumulated events, interception rainfall accumulated event frequency, and frequency difference corresponding to the interception standard of 3 mm to 11 mm in a typical year;

[0057] (3) As shown in Table 1, when the initial rain interception standard is 4 mm, there are 89 effective rainfalls with rainfall below the interception standard, and the cumulative frequency of interception rainfall is 61.0%; when the initial rain interception standard is 8 mm, 106 effective rainfalls can be completely intercepted throughout the year, and the cumulative frequency of interception rainfall is 72.6%;

[0058] (4) Taking 4 mm / rainfall as the starting point, Figure 4It indicates that with the increase of the initial rain interception standard, the cumulative frequency difference of complete interception rainfall is Figure 1 It can be seen that with the increase of the interception standard, the cumulative frequency of completely intercepted rainfall continues to increase, and the frequency difference of the cumulative number of intercepted rainfalls generally shows a trend of first increasing and then decreasing. When the interception standard does not exceed 8 mm, the frequency difference of the cumulative number of intercepted rainfalls shows an increasing trend. After exceeding 8 mm, it shows an overall decreasing trend, indicating that the 8 mm interception standard is the inflection point of the curve, that is, the recommended value of the initial rain interception standard in the embodiment is 8 mm.

[0059] Table 1 Example Rainfall interception rate determination initial rainwater interception standard display table

[0060]

[0061] Step 3: Based on the 5-minute step rainfall data of a typical year, filter the typical rainfall data. The specific process is as follows:

[0062] (1) According to the survey, the design standard of the drainage network in the project area is mostly once in three years. This time, the rainfall once in three years is selected as the typical rainfall event. The typical rainfall once in three years in this area is about 63mm. The following three rainfall events are the critical rainfall events with a rainfall of about 63mm in 2012:

[0063] ① September 9, 2012: Total rainfall was 67 mm, rainfall lasted 355 minutes, and the first 8 mm of rainfall lasted 75 minutes.

[0064] ②August 26, 2012: Total rainfall was 68.5 mm, the rainfall lasted 115 minutes, and the first 8 mm of rainfall lasted 8 minutes.

[0065] ③May 29, 2012: Total rainfall was 70.5 mm, the rainfall lasted 535 minutes, and the first 8 mm of rainfall lasted 220 minutes.

[0066] (2) Further analysis shows that the two rainfall events on September 9 and August 26, 2012, were of short duration and early rain peaks. The critical line of the first 8 mm rainfall was located near the rain peak. The initial rainfall was not obvious. Both rainfall events were short-duration extreme rainstorms and could not be used for the study of initial rainfall control. Therefore, it is recommended to take the rainfall event on May 29, 2012 as a typical rainfall event to determine the interception scale of the initial rain storage pool.

[0067] Step 4: Use SWMM to build a numerical model of the drainage network in the project area, as shown in the figure Figure 7 The SWMM model generalization schematic diagram of the embodiment of the present invention is shown in FIG. 1 , and the specific model building process is as follows:

[0068] Collect the basic data required for the construction of the SWMM drainage network numerical model in the project area, including but not limited to: the rainwater network data, terrain elevation data, underlying surface data, etc. in the project area, among which the rainwater network data includes pipe size, pipe material, upstream and downstream pipe bottom elevation, rainwater well size, well bottom elevation and well depth, etc.;

[0069] Divide drainage zones and determine the model surface runoff path based on the project area's rainwater pipe network data, rainwater well data, and topographic data;

[0070] Using ArcGIS software, the area, characteristic width and other parameters of each drainage zone were extracted respectively; based on the underlying surface data of the project area, the proportion of impervious area of ​​each drainage zone was calculated (roads, pavements, and building roofs are impervious areas, and green spaces and bare land are permeable areas); based on the ground elevation data of the project area, the DEM data of the project area was generated, and the slope of each drainage zone was calculated;

[0071] According to the pipeline network data of the project area, improve the connection node characteristics and pipeline characteristics of the pipeline network model, including the internal elevation and depth of the inspection well, the elevation of the upstream and downstream bottom of the pipeline, the shape of the pipeline, the geometric dimensions of the section, the fullness, the roughness coefficient, etc.;

[0072] Other parameters that must be input to set the SWMM drainage network numerical model include but are not limited to Manning's n value of overland flow, surface depression storage, infiltration model parameters, calculation model, evaporation and other parameters.

[0073] Step 5: Input the first 8mm 5-minute step rainfall process of a typical rainfall event into the SWMM drainage network numerical model for simulation. The step size of the model output result is set to 5 minutes. The simulation results show that the rainfall starts at 2:00, the outflow starts at 2:55, the first 8mm rainfall ends at 5:40, and the outflow ends at t1 of the first 8mm rainfall at 7:55. The total flow rate before 7:55 during the entire rainfall outflow process is taken as the interception scale of the initial rain storage pool.

[0074] Step 6: Input the entire 5-minute step rainfall process of a typical event into the SWMM drainage network numerical model for simulation. The model output result step is set to 5 minutes. According to the simulation results, before 7:55, the outflow peak of the area is 6.71m 3 / s, the total outflow, i.e. the initial rain interception scale, is 42,000 m 3 Considering that the storage tank is emptied in 2 days and the design scale of the treatment facility, the design scale of the proposed initial rain storage tank and treatment facility is 33,000 m 3 and 17,000 m 3 / d. For detailed model output results, see the attached Figure 8 .

[0075] The present invention adopts the measured long series rainfall data, determines the interception standard of the initial rain storage tank through the statistical theoretical method, takes into account the temporal and spatial differences and uncertainty of rainfall, and the initial rain interception standard obtained is more universal and reasonable; based on typical rainfall data, the present invention adopts the drainage network numerical model to simulate and calculate the scale of the storage tank, takes into account the dynamic convergence process of the initial rainwater, and is more scientific and reasonable than the scale of the storage tank obtained by the existing commonly used empirical formula method.

[0076] like Fig. 9 As shown, a system for determining the size of an initial rain storage pool based on the interception rate of rainfall events includes:

[0077] The rainfall data selection module selects long series hourly rainfall data and filters out the 5-minute step rainfall data of typical years based on the long series rainfall data;

[0078] The interception standard recommended value calculation module divides the long series / typical year rainfall events, sorts the rainfall events from small to large according to rainfall, counts the effective rainfall above 2 mm and its corresponding cumulative rainfall events, calculates the percentage of each rainfall cumulative event in the total effective rainfall events above 2 mm as the interception rainfall cumulative event frequency, analyzes the interception rainfall cumulative event frequency difference corresponding to each adjacent rainfall, establishes a relationship curve between rainfall and its interception rainfall cumulative event frequency difference, selects the inflection point of the curve, and the rainfall corresponding to the inflection point is the interception standard recommended value;

[0079] The design rainfall screening module selects representative typical rainfall events as the design rainfall based on the 5-minute step rainfall data in a typical year;

[0080] Model building module, which builds the numerical model of the drainage network in the study area;

[0081] The water collection time calculation module inputs the initial rainwater portion corresponding to the interception standard determined in the typical rainfall data, and simulates the water collection time t1 required for all the initial rainwater to be collected;

[0082] The design scale calculation module of the first rain storage tank inputs typical rainfall data, simulates the total outflow in the first t1 period under typical rainfall conditions as the interception scale of the storage tank, and considers the treated water volume of the first rain treatment facilities in the first t1 period to obtain the design scale of the first rain storage tank.

[0083] An embodiment of the present application provides a computer-readable storage medium, which stores program code. When the program code is executed by a processor, the steps of the method for determining the scale of an initial rain storage pool based on the interception rate of rainfall events as described above are implemented.

[0084] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0085] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0088] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0089] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0090] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0091] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0092] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for determining the scale of an initial rain storage pool based on the interception rate of rainfall events, characterized in that: The specific steps include: Step 1: Select the long series of hourly rainfall data, and filter out the 5-minute step rainfall data of typical years based on the long series rainfall data; Step 2: Divide the long series / typical year rainfall events, sort the rainfall events from small to large according to rainfall, count the effective rainfall above 2 mm and its corresponding cumulative rainfall events, calculate the percentage of each rainfall cumulative event in the total effective rainfall events above 2 mm as the interception rainfall cumulative event frequency, analyze the interception rainfall cumulative event frequency difference corresponding to each adjacent rainfall, establish a relationship curve between rainfall and its interception rainfall cumulative event frequency difference, select the inflection point of the curve, and the rainfall corresponding to the inflection point is the interception standard recommended value; Step 3: Based on the 5-minute step rainfall data in a typical year, select representative typical rainfall events as the design rainfall; Step 4: Construct a numerical model of the drainage network in the study area; Step 5: Input the initial rainwater portion corresponding to the interception standard determined in step 1 in the typical rainfall data, and simulate the water collection time t1 required for the collection of all the initial rainwater; Step 6: Input typical rainfall data, simulate the total outflow in the first t1 period under typical rainfall conditions as the interception scale of the storage tank, consider the amount of water treated by the initial rain treatment facilities in the first t1 period, and obtain the design scale of the initial rain storage tank.

2. A method for determining the scale of an initial rain storage pool based on the interception rate of rainfall events according to claim 1, characterized in that: The typical year 5-minute step rainfall data selects an annual rainfall close to the multi-year average, and its temporal and spatial distribution characteristics of annual rainfall are also close to the multi-year average.

3. The method for determining the scale of the initial rain storage pool based on the interception rate of rainfall events according to claim 1, characterized in that: The rainfall events are continuous rainfall with an interval of not less than 2 hours, and effective rainfall is rainfall events with a rainfall of more than 2 mm. The formula for the cumulative frequency of interception rainfall events is: Among them, p n is the cumulative frequency of interception rainfall, n is the ranking number of interception rainfall from small to large in the effective rainfall events, and m is the total number of effective rainfall events in the long series of rainfall.

4. The method for determining the scale of the initial rain storage pool based on the interception rate of rainfall events according to claim 1, characterized in that: The drainage network numerical model is constructed using SWMM open source software or InfoWorks ICM, MIKE urban commercial software. The data required to construct the drainage network numerical model include but are not limited to: rainwater network data, terrain elevation data, and underlying surface data, wherein the rainwater network data includes pipe size, pipe material, upstream and downstream pipe bottom elevations, rainwater well size, well bottom elevation, and well depth.

5. The method for determining the scale of the initial rain storage pool based on the interception rate of rainfall events according to claim 1, characterized in that: The initial rainwater portion corresponding to the interception standard determined in step 1 in the input typical rainfall data is simulated, and the water collection time t1 required for collecting all the initial rainwater is specifically: Draw a rainfall accumulation curve or table with a 5-minute step length for typical rainfall events. According to the initial rain interception standard determined in step 1, the rainfall process with the accumulated rainfall of typical rainfall events equal to the initial rain interception standard is used as the rainfall data of typical initial rain events to input into the model; The model simulation calculation starts, the model output step is 5 minutes, and the moment when the terminal outflow is 0 is the confluence time t1 required for all the initial rainwater to be intercepted.

6. The method for determining the scale of the initial rain storage pool based on the interception rate of rainfall events according to claim 1, characterized in that: The input typical rainfall data is used to simulate the total outflow in the first t1 period under typical rainfall conditions as the interception scale of the storage tank. Considering the treated water volume of the initial rain treatment facility in the first t1 period, the design scale of the initial rain storage tank is obtained as follows: Input the typical rainfall data obtained in step 2 into the model; Start the model simulation calculation, the model output step is 5 minutes, and output the flow process at the end of the drainage network; The cumulative flow from the beginning of the terminal outflow to the moment t1 is the interception scale of the initial rain storage pool; The minimum storage capacity of the regulating reservoir is the cumulative flow before time t1 minus the total treated water volume. The equation of the flow rate changing over time is solved as follows: Where: V is the scale of the regulating reservoir; t is the time from the start of water inflow to the stop of water inflow; t1 is the regulating time; Q in —Rainfall terminal flow; Q out —The treatment capacity of initial rainwater treatment facilities.

7. A system for determining the size of an initial rain storage pool based on the interception rate of rainfall events, characterized in that: include, The rainfall data selection module selects long series hourly rainfall data and filters out the 5-minute step rainfall data of typical years based on the long series rainfall data; The interception standard recommended value calculation module divides the long series / typical year rainfall events, sorts the rainfall events from small to large according to rainfall, counts the effective rainfall above 2 mm and its corresponding cumulative rainfall events, calculates the percentage of each rainfall cumulative event in the total effective rainfall events above 2 mm as the interception rainfall cumulative event frequency, analyzes the interception rainfall cumulative event frequency difference corresponding to each adjacent rainfall, establishes a relationship curve between rainfall and its interception rainfall cumulative event frequency difference, selects the inflection point of the curve, and the rainfall corresponding to the inflection point is the interception standard recommended value; The design rainfall screening module selects representative typical rainfall events as the design rainfall based on the 5-minute step rainfall data in a typical year; Model building module, which builds the numerical model of the drainage network in the study area; The water collection time calculation module inputs the initial rainwater portion corresponding to the interception standard determined in the typical rainfall data, and simulates the water collection time t1 required for all the initial rainwater to be collected; The design scale calculation module of the first rain storage tank inputs typical rainfall data, simulates the total outflow in the first t1 period under typical rainfall conditions as the interception scale of the storage tank, and considers the treated water volume of the first rain treatment facilities in the first t1 period to obtain the design scale of the first rain storage tank.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program codes, and when the program codes are executed by a processor, the steps of the method for determining the scale of an initial rain storage pool based on the interception rate of rainfall events as described in any one of claims 1 to 6 are implemented.

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