A waterlogging prevention runoff simulation method suitable for urban scale

Abstract

The present application relates to the technical field of drainage facility design, and particularly relates to a waterlogging prevention runoff simulation method suitable for urban scale, comprising: S1: establishing a plurality of drainage subareas in a city area, and selecting a plurality of typical drainage subareas from the drainage subareas; S2: establishing a drainage model for each typical drainage subarea respectively; S3: simulating a rainfall event on the drainage model, and obtaining a typical trial runoff of the typical drainage subarea; and S4: generating a total runoff required for waterlogging prevention in the city area according to the typical trial runoff. The beneficial effect is that: by dividing the city area and selecting typical drainage subareas for simulation, the simulation of a small number of drainage subareas can obtain the typical trial runoff reflecting the same type of drainage subarea, and then the total runoff of the entire city scale is obtained, which realizes the estimation of the runoff of the city waterlogging, reduces the number of areas required for modeling, and further reduces the modeling complexity of the overall project.

Description

Technical Field

[0001] This invention relates to the field of drainage facility design technology, and more specifically to a method for simulating runoff for urban flood control at the city scale. Background Technology

[0002] Urban flooding severely impacts people's lives and livelihoods, even endangering their lives and property, and is a significant constraint on safe urban development. Addressing urban flooding is a concrete measure that prioritizes ecology and safety. Against this backdrop, rationally determining the scale of urban flood control runoff becomes a crucial factor influencing the formulation of drainage and flood control plans, system layout, and engineering investment.

[0003] In existing technologies, the calculation of the scale of urban flood control systems is mainly carried out through trial calculations using inference formulas or hydraulic models. The inference formula method employs runoff calculation methods under flood control standards specified in standards such as the *Outdoor Drainage Design Standard* (GB50014-2021) and the *Technical Specification for Urban Flood Control* (GB51222-2017). The advantage of the inference formula method lies in its lower computational difficulty, fewer required external boundary conditions, and overall simplicity. The hydraulic model method utilizes modeling software such as InfoWorks to establish one-dimensional and two-dimensional coupled hydraulic models of the city, dynamically simulating the dynamic changes of urban flooding during rainfall events and surface runoff generation, thereby determining the total runoff scale that the urban flood control system needs to handle under given design boundary conditions. The advantage of the hydraulic model method is its ability to comprehensively and accurately reproduce the actual operation of the urban drainage and flood control system, as well as the actual impact of flooding under these conditions, thus obtaining more accurate data on the scale of urban flood control runoff.

[0004] However, in practical implementation, the inventors found that the hydraulic model method requires the establishment of a complete hydraulic model for the area to be planned. When the planning scale expands to the city scale, it requires survey data on topography, pipe networks, and river channels, as well as related geographical and hydraulic data, as a foundation for constructing a model reflecting the city as a whole. This results in a complex topological structure, a large workload, and often insufficient stability. Furthermore, it requires the participation of model engineers with sufficient professional skills to ensure the final modeling effect. Currently, urban drainage and flood control planning and design in my country often lacks these basic conditions, and project cycles are relatively short. Therefore, the comprehensive application of the hydraulic model method at the city scale often lacks the corresponding basic and human resources. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, a method for simulating runoff for urban flood control is provided.

[0006] The specific technical solution is as follows:

[0007] A method for simulating runoff for urban flood control, applicable at the city scale, includes:

[0008] Step S1: Establish multiple drainage zones within the urban area, and select multiple typical drainage zones from the drainage zones;

[0009] Step S2: Establish a drainage model for each of the typical drainage zones;

[0010] The drainage model is used to characterize the drainage network, pumping stations, and waterways in the typical drainage zone.

[0011] Step S3: Simulate rainfall events on the drainage model to obtain typical trial runoff for the typical drainage zone;

[0012] Step S4: Generate the total runoff volume required for urban flood control in the urban area based on the typical trial runoff volume.

[0013] Preferably, step S1 includes:

[0014] Step S11: Divide the urban area into multiple drainage zones and obtain the background conditions of each drainage zone;

[0015] Step S12: Set the drainage zones with similar background conditions into the same drainage zone group;

[0016] Step S13: Select one typical drainage zone in each of the drainage zone groups.

[0017] Preferably, in step S2, the method for establishing the drainage model includes:

[0018] Step S21: Construct pipe network models and river models for the typical drainage zones respectively;

[0019] Step S22: Construct a local ground model of the typical drainage zone based on the survey data of the typical drainage zone;

[0020] Step S23: Add the pipeline model and the river model to the local ground model to generate the drainage model.

[0021] Preferably, step S2 includes:

[0022] Step S31: Generate simulated rainfall events based on the design rainfall pattern and the return period of the rainstorm, and set the initial flow rate value of the pumping station in the typical drainage zone as the drainage flow rate;

[0023] Step S32: Perform the simulated rainfall event on the typical drainage zone to obtain drainage results;

[0024] Step S33: Change the drainage flow rate, and then repeat step S22 to collect multiple drainage results and record the drainage flow rate corresponding to the drainage results;

[0025] Step S34: Filter the drainage results and retain only the drainage results that do not pose a risk of waterlogging. Then select the minimum drainage flow rate among the drainage results as the trial flow rate of the pumping station.

[0026] Step S35: Generate the surface runoff to be treated for the typical drainage zone based on the calculated flow rate of the pumping station.

[0027] Preferably, the method further includes the following steps before performing step S32:

[0028] Step S301: Obtain the drainage outlets and intercepting pipe sections in the drainage model;

[0029] Step S302: Set the upstream flow rate of the typical drainage zone according to the intercepting pipe section, and establish a binding relationship between the upstream flow rate and the specific drainage outlet of the pipe network.

[0030] Preferably, before performing step S35, a time-series calculation process is further included to obtain the pump station operating time and the river backwater duration in the drainage results;

[0031] The timing calculation process includes:

[0032] Obtain each flap valve installed at the drainage outlet of the drainage network, and search for the drainage process corresponding to the drainage result based on the flap valve to obtain the closing time period of each flap valve;

[0033] The closure period is taken as the duration of the river channel backwater and the operating time of the pumping station.

[0034] Preferably, in step S35, the method for generating the typical trial runoff based on the trial flow of the pumping station includes:

[0035] V1 = 3600 * Q1 * T1;

[0036] In the formula:

[0037] V1 represents the typical trial runoff volume, in m³. 3 ;

[0038] Q1 is the calculated flow rate of the pumping station, in cubic meters per second (m³). 3 / s;

[0039] T1 represents the pump station operating time during the simulated rainfall event, measured in hours (h).

[0040] Preferably, step S4 includes:

[0041] Step S41: Based on the typical trial runoff, generate the estimated runoff for each drainage zone in the drainage zone group to which the typical drainage zone is located;

[0042] Step S42: Based on the estimated runoff of the drainage zones, generate the group prevention runoff for each drainage zone group;

[0043] Step S43: Based on the sum of the runoff volumes of all the groups, obtain the total runoff volume required for urban flood control in the urban area.

[0044] Preferably, in step S41, the method for generating the estimated runoff of the drainage zone based on the typical trial runoff includes:

[0045] V i =V1*(P i / P1)*(A i / A1)*(T i / T1)

[0046] In the formula:

[0047] V i Estimate the runoff volume for the drainage zone, in m³. 3 ;

[0048] V1 represents the typical trial runoff volume, in m³. 3 ;

[0049] P i The percentage of the risk area within the drainage zone;

[0050] P1 represents the percentage of the risk area within the typical drainage zone;

[0051] A1 represents the area of ​​the drainage zone, in km². 2 ;

[0052] A i The area of ​​the typical drainage zone is given in km². 2 ;

[0053] T1 represents the duration of backwater in the typical drainage zone, in hours.

[0054] T i The duration of the backwater effect in the drainage zone is expressed in hours (h).

[0055] Preferably, the baseline conditions include at least one of the following: regional area, topography, development level, river hydrological and hydraulic conditions, stormwater pipe density, stormwater pipe drainage capacity, stormwater drainage pumping station scale, and storage facility scale.

[0056] The above technical solution has the following advantages or beneficial effects: by dividing the urban area into several drainage zones, and selecting typical drainage zones for rainfall simulation, it is possible to obtain typical trial runoff reflecting the waterlogging runoff of the same type of drainage zone by simulating and calculating a small number of drainage zones. Then, the total runoff required for urban waterlogging prevention and control of the entire city can be deduced from the typical trial runoff. While realizing the estimation of urban waterlogging runoff, it reduces the number of areas that need to be modeled, thereby reducing the modeling complexity of the overall project. Attached Figure Description

[0057] Embodiments of the invention will be described more fully with reference to the accompanying drawings. However, the drawings are for illustration and explanation only and do not constitute a limitation on the scope of the invention.

[0058] Figure 1 This is a schematic diagram of the runoff simulation method for urban flood control in an embodiment of the present invention;

[0059] Figure 2 This is a schematic diagram of sub-step S1 in an embodiment of the present invention;

[0060] Figure 3 This is a schematic diagram of sub-step S2 in an embodiment of the present invention;

[0061] Figure 4 This is a schematic diagram of the pipeline network model establishment method in an embodiment of the present invention;

[0062] Figure 5 This is a schematic diagram of the river channel model establishment method in an embodiment of the present invention;

[0063] Figure 6 This is a schematic diagram of a local ground model creation method in an embodiment of the present invention;

[0064] Figure 7 This is a schematic diagram of sub-step S3 in an embodiment of the present invention;

[0065] Figure 8 This is a schematic diagram of the method for setting up the intercepting pipe section in an embodiment of the present invention;

[0066] Figure 9 This is a schematic diagram of sub-step S4 in an embodiment of the present invention;

[0067] Figure 10 This is a schematic diagram of the drainage zoning in an embodiment of the present invention;

[0068] Figure 11 This is a schematic diagram of the pipeline network in an embodiment of the present invention;

[0069] Figure 12 This is a schematic diagram of a pumping station in an embodiment of the present invention. Detailed Implementation

[0070] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0072] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0073] This invention includes:

[0074] A method for simulating runoff for urban flood control, such as... Figure 1 As shown, it includes:

[0075] Step S1: Establish multiple drainage zones within the urban area, and select multiple typical drainage zones from these zones;

[0076] Step S2: Establish a drainage model for each typical drainage zone;

[0077] Drainage models are used to characterize drainage networks, pumping stations, and waterways in typical drainage zones;

[0078] Step S3: Simulate rainfall events in the drainage model to obtain typical trial runoff for typical drainage zones;

[0079] Step S4: Generate the total runoff volume required for urban flood control in the urban area based on typical trial runoff volumes.

[0080] Specifically, addressing the issue that existing water body modeling methods for simulating urban-scale flooding require modeling the entire urban area, resulting in a large workload and complex structure, this embodiment divides the urban area into multiple drainage zones and selects typical drainage zones that can characterize the drainage zones. Then, by modeling and simulating the typical drainage zones, the typical trial runoff of a certain type of drainage zone is obtained. Subsequently, the total runoff required for urban flooding prevention and control in the entire urban area can be obtained by regression. Moreover, the above process only requires modeling the typical drainage zones, greatly reducing the workload of modeling.

[0081] In implementation, the above method is set up as a software embodiment in a computer device to assist engineers in estimating the total runoff required for urban flood control during the planning process of urban drainage facilities, thereby guiding subsequent drainage facility planning and design work. Here, a drainage zone refers to a general drainage area derived from the city's drainage network planning. Each drainage zone has a drainage network with a specific orientation, pumping stations distributed within the network, and some drainage zones also include waterways and nodes that carry upstream flow. Rainfall events are used for simulation.

[0082] In a preferred embodiment, such as Figure 2 As shown, step S1 includes:

[0083] Step S11: Divide the urban area into multiple drainage zones and obtain the background conditions for each drainage zone;

[0084] Step S12: Set drainage zones with similar background conditions into the same drainage zone group;

[0085] Step S13: Select a typical drainage zone in each drainage zone group.

[0086] Specifically, addressing the issue that existing water body modeling methods for simulating urban-scale flooding require modeling the entire urban area, resulting in significant workload and complex structures, this embodiment divides the urban area into multiple drainage zones. Baseline conditions are extracted for each zone, and based on these conditions, zones with similar background conditions are grouped together. This selection process can be implemented using existing clustering algorithms, such as KNN and K-means, and the weights of different baseline conditions can be adjusted according to the specific needs of the planned city to achieve better clustering results for the drainage zones. Subsequently, within the defined drainage zone group, further selection is made based on the baseline conditions to obtain typical drainage zones representing several drainage zones within the same group. This process can be achieved by treating a single drainage zone group as a class, calculating the centroid for multiple drainage zones within the group, and selecting the drainage zone closest to the centroid as the typical drainage zone. In other embodiments, typical drainage zones can also be selected using other methods. For example, in another embodiment, a condition such as "the area of ​​the drainage zone is ≥2km²" is set. 2 "These screening rules obtain typical drainage zones through screening and sorting. By selecting typical drainage zones using the above method, several drainage zones within the same drainage zone group can be effectively represented. In subsequent modeling, the simulated runoff of waterlogging in other drainage zones within the same drainage zone group can be obtained by regressing the hydraulic model simulation of the typical drainage zone, thereby reducing the workload of modeling and achieving a faster simulation process."

[0087] In a preferred embodiment, the background conditions include at least one of the following: area, topography, development level, river hydrological and hydraulic conditions, stormwater pipe density, stormwater pipe drainage capacity, stormwater drainage pumping station scale, and storage facility scale.

[0088] Specifically, in order to achieve a better clustering effect for drainage zones, in this embodiment, the baseline conditions are selected as at least one of the following: area, topography, development level, river hydrological and hydraulic conditions, stormwater pipe density, stormwater pipe drainage capacity, stormwater drainage pumping station scale, and storage facility scale. This allows drainage zones with similar baseline conditions to be grouped into the same drainage zone group. In the subsequent modeling process, multiple drainage zones in the same drainage zone group can be effectively represented by a single typical drainage zone.

[0089] In a preferred embodiment, such as Figure 3 As shown, step S2 includes:

[0090] Step S21: Construct pipe network models and river models for typical drainage zones respectively;

[0091] Step S22: Construct a local ground model of a typical drainage zone based on the survey data of the typical drainage zone;

[0092] Step S23: Add the pipe network model and the river model to the local ground model to generate the drainage model.

[0093] Specifically, to achieve better simulation results, this embodiment constructs one-dimensional pipe network models and river models in typical drainage zones to represent the rivers and pipe networks within those zones. Subsequently, a local surface model of the typical drainage zone is constructed using pre-collected survey data. This local surface model primarily represents the topography, surface elevation, and other data of the typical drainage zone, which is then used to obtain surface runoff in subsequent rainfall event simulations. After generating the pipe network model, river model, and local surface model, the three models are stitched together to obtain a complete hydraulic model, serving as the drainage model for the typical drainage zone.

[0094] As an optional implementation method, such as Figure 4 As shown, step S21, the steps for establishing the pipeline network model, include:

[0095] Step A211: Obtain the pipe network survey data of typical drainage zones, and extract the data of rainwater wells and drainage pipes from the pipe network survey data;

[0096] The data includes attribute information for rainwater wells and drainage pipes;

[0097] The attribute information of the rainwater well includes: the spatial location of the rainwater well and the spatial elevation of the rainwater well;

[0098] The attribute information of drainage pipes includes: upstream and downstream numbers of drainage pipes, upstream and downstream bottom elevations of drainage pipes, pipe diameter of drainage pipes, material of drainage pipes, and system type.

[0099] Step A212: Import the data into the hydraulic modeling software to form the pipeline topology;

[0100] Step A213: Based on the pipeline topology, define the sub-catchment areas and complete the pipeline network model construction.

[0101] As an optional implementation method, such as Figure 5 As shown, step S21, the steps for establishing the river channel model, include:

[0102] Step B211: Obtain the basic hydraulic elements of a typical drainage zone, construct the hydraulic cross-section of the river channel based on the basic hydraulic elements, and obtain at least one river channel centerline based on the basic hydraulic elements.

[0103] Step B212: Construct the riverbank boundaries on both sides of the river model using the river centerline as a reference point;

[0104] Step B213: Generate a roughness coefficient based on the material of the river channel hydraulic section, and input the upstream and downstream hydraulic boundary conditions. Adjust the roughness coefficient and the upstream and downstream hydraulic boundaries to complete the construction of the river channel model.

[0105] As an optional implementation method, such as Figure 6 As shown, in step S22, the method for generating a local ground model based on surveying data includes:

[0106] Step C221: Obtain ground elevation point data for typical drainage zones from the self-survey data;

[0107] Step C222: Establish a model network for typical drainage zones based on survey data, and generate a ground elevation system based on ground elevation point data and the model network;

[0108] Step C223: Generate a local ground model based on the ground elevation system, and correct the local ground model according to the surface runoff situation.

[0109] In a preferred embodiment, such as Figure 7 As shown, step S2 includes:

[0110] Step S31: Generate simulated rainfall events based on the design rainfall pattern and the return period of the rainstorm, and set the initial flow rate value of the pump station in the drainage model as the drainage flow rate;

[0111] Step S32: Perform a simulated rainfall event on the drainage model to obtain drainage results;

[0112] Step S33: Change the drainage flow rate, and then repeat step S22 to collect multiple drainage results and record the drainage flow rate corresponding to the drainage results;

[0113] Step S34: Filter the drainage results and retain only those that do not pose a risk of flooding. Then select the minimum drainage flow rate from the drainage results as the calculated flow rate for the pumping station.

[0114] Step S35: Generate the surface runoff to be treated for typical drainage zones based on the trial flow of the pump station.

[0115] Specifically, in order to achieve better simulation results, this embodiment simulates rainfall multiple times on the drainage model and adjusts the drainage flow of the pumping station during the rainfall simulation to obtain the minimum flow that can eliminate urban flooding, which is then used as the simulated trial flow of the pumping station.

[0116] During implementation, the design rainfall pattern refers to the total design rainfall amount and distribution pattern under specific rainfall history and intervals, which can be obtained based on methods such as the Chicago rainfall pattern and the same-frequency analysis method. The return period of the rainstorm is determined by the flood-bearing capacity requirements of this water conservancy facility design. For example, the water conservancy facilities planned in this project need to withstand a "once-in-50-year" or "once-in-a-century" rainfall event. Drainage results include the water level height at each simulated monitoring point in the drainage model, as well as the change in water level height over time. Before starting the simulation, the flood risk control standards for each drainage zone have been pre-determined based on the design requirements of the water conservancy facilities, including water depth and water duration. For example, in one embodiment, the flood risk control standard includes "the water depth in the drainage zone exceeds 30cm for no more than 3 hours during rainfall, and the surface water depth does not exceed 15cm after 2 hours of receding water." Based on this condition, a rule engine is used to filter the drainage results to obtain the actual drainage flow rate of the pumping station that meets the flood risk control standard, and the drainage flow rate with the smallest flow rate is used as the calculated flow rate output of the pumping station.

[0117] In a preferred embodiment, such as Figure 8 As shown, the procedure before step S32 includes:

[0118] Step S301: Obtain the drainage outlets and intercepting pipe sections in the drainage model;

[0119] Step S302: Set the upstream flow rate of a typical drainage zone according to the intercepting pipe section, and establish a binding relationship between the upstream flow rate and a specific pipe network drainage outlet.

[0120] Specifically, in order to achieve a better simulation effect of the actual drainage situation of various drainage zones, in this embodiment, a flap valve for backflow prevention is set at the drainage outlet of the pipeline network, and a flow interception pipe section is set up to intercept and transfer the upstream flow of each outlet to the newly set pump station model node and the corresponding pump station outlet pipe node, so as to establish a more accurate drainage model.

[0121] In a preferred embodiment, before performing step S35, a time-series calculation process is further included to obtain the pump station operating time and the river backwater duration in the drainage results.

[0122] The timing calculation process includes:

[0123] Obtain the flap valves installed at the drainage outlets of the drainage network, find the drainage process corresponding to the drainage results based on the flap valves, and obtain the closing time period of each flap valve;

[0124] The closure period will be used as the duration of the river channel backwater operation, as well as the pump station operation time.

[0125] Specifically, before simulating rainfall events, a binding relationship is established between the flap gates and the corresponding pumping stations. During the simulated rainfall events, when there is no backwater in the river channel, drainage is carried out through surface runoff and the drainage network. In this case, the flap gates open and the corresponding pumping stations close. When backwater occurs in the river channel, the flap gates close, and the pumping stations drain the water. By recording the drainage process during this event, the duration of backwater and the operating time of the pumping stations can be recorded.

[0126] In a preferred embodiment, step S35, the method for generating typical trial runoff based on the trial flow of the pumping station, includes:

[0127] V1 = 3600 * Q1 * T1; (Equation 1)

[0128] In the formula:

[0129] V1 represents a typical trial runoff volume, in cubic meters per second (m³). 3 ;

[0130] Q1 is the calculated flow rate of the pumping station, in cubic meters per second (m³). 3 / s;

[0131] T1 represents the pump station operating time during the simulated rainfall event, measured in hours (h).

[0132] In a preferred embodiment, such as Figure 9 As shown, step S4 includes:

[0133] Step S41: Generate the estimated runoff of each drainage zone in the drainage zone group where the typical drainage zone is located, based on the typical trial runoff.

[0134] Step S42: Based on the estimated runoff from the drainage zones, generate the group prevention runoff for each drainage zone group;

[0135] Step S43: Based on the sum of all the group-controlled runoff volumes, obtain the total runoff volume required for urban flood control in the urban area.

[0136] Specifically, addressing the issue that existing water model methods for simulating urban-scale flooding require modeling the entire urban area, resulting in significant workload and complex structures, this embodiment achieves a better estimation of the total urban flooding control required for urban flooding control. This facilitates subsequent planning of water conservancy facilities based on the estimated total urban flooding control required for urban flooding control planning.

[0137] In a preferred embodiment, step S41, the method for generating drainage zone estimated runoff based on typical trial runoff, includes:

[0138] V i =V1*(P i / P1)*(A i / A1)*(T i / T1); (Equation 2)

[0139] In the formula:

[0140] V i Estimate runoff for drainage zones, in m³. 3 ;

[0141] V1 represents a typical trial runoff volume, in cubic meters per second (m³). 3 ;

[0142] P i The percentage of the risk area within the drainage zone;

[0143] P1 represents the percentage of risk area within a typical drainage zone;

[0144] A1 represents the area of ​​the drainage zone, in km². 2 ;

[0145] A i The area of ​​a typical drainage zone is shown in km². 2 ;

[0146] T1 represents the duration of backwater in a typical drainage zone, expressed in hours.

[0147] T i The duration of backwater in the drainage zone, expressed in hours.

[0148] During implementation, the drainage model analyzed the surface runoff portion in the local ground model and the pipe network model to identify areas that might experience flooding during rainfall. These areas were designated as risk areas. Based on the area and river backwater time between different drainage zones, the typical trial runoff of a typical drainage zone was converted to the estimated runoff of the corresponding drainage zone. This enabled the estimation of other drainage zones based on the simulation results of typical drainage zones.

[0149] The present invention will be further described below with reference to specific embodiments:

[0150] like Figure 10 As shown, based on nine drainage zones (SA0-SA3, SB0-SB4) within the urban flood runoff area, runoff calculation drainage zone groups were divided, including drainage zone classification and selection of drainage zones with typical urban flood risk. In the figure, white background with black borders represents the divided drainage zones; dots filled with black borders represent waterways.

[0151] Drainage Zoning Classification: Based on baseline drainage and flood control conditions, including but not limited to regional area, topography, development level, river hydrological and hydraulic conditions, stormwater pipe density, stormwater pipe drainage capacity, stormwater (flood control) pumping station scale, and storage facility scale, the nine drainage zones are divided into two runoff calculation drainage zone groups: Group A and Group B. Group A has a total area of ​​16.7 km², including drainage zones SA0, SA1, SA2, and SA3. Group B has a total area of ​​17.6 km², including drainage zones SB0, SB1, SB2, SB3, and SB4.

[0152] Selection of typical urban waterlogging risk drainage zones: SA0 and SB0 were selected from Group A and Group B, respectively, as typical waterlogging risk drainage zones within each runoff calculation drainage zone group. The area of ​​drainage zone SA0 is 3.1 km2, and the area of ​​drainage zone SB0 is 2.4 km2, both of which meet the requirements for modeling and analysis.

[0153] like Figure 11 As shown, based on urban pipe network and river survey data, a one-dimensional pipe network model and a one-dimensional river model were constructed within nine drainage zones in the urban surface runoff area. In the figure, the white background with black borders represents the divided drainage zones; the dots filled with black borders represent rivers; and the black lines represent the pipe networks within the drainage zones.

[0154] The pipeline network model includes all stormwater pipes and channels within 9 drainage zones, comprising 170km of pipe sections and 4300 manhole nodes. Basic attributes imported for pipelines include upstream and downstream pipe numbers, upstream and downstream bottom elevations, pipe diameter, material, and system type. Attributes imported for manholes include spatial location and ground elevation.

[0155] The river model includes three rivers within the urban flood runoff area, namely R1, R2, and R3. Based on the basic hydraulic elements of the three rivers and the hydraulic boundary conditions of the upstream and downstream of the input rivers, a corresponding one-dimensional river model network is constructed.

[0156] By connecting the nodes of the river model and the pipeline model, a combined pipeline-river model is constructed for nine drainage zones within the urban surface runoff area.

[0157] Two-dimensional integrated models were constructed as drainage models for the typical urban flooding risk drainage zones SA0 and SB0 respectively:

[0158] Ground vertical elevation data collected through surveying is input into the model network to generate a ground elevation system. Local terrain nodes (including but not limited to road curbs, bridges, and tunnels) are then corrected. Finally, the ground elevation system is connected to a one-dimensional pipe network-river channel model to establish a drainage model representing typical drainage zones.

[0159] Based on the establishment of the model network, the scale of runoff for urban flood control is calculated within the urban flood runoff generation area.

[0160] First, a trial calculation of the runoff model for typical urban flood risk drainage zones was conducted, dividing SA0 and SB0 into drainage zones.

[0161] like Figure 12 As shown, flap gate nodes are set at the outlet nodes of the one-dimensional river model connecting the one-dimensional pipe network models of the two drainage zones, and intercepting pipe sections are set to intercept and transfer the upstream flow of the two drainage zone outlets to the newly established pump station model nodes (pump station PSA for drainage zone SA0, and pump station PSB for drainage zone SB0) and the corresponding pump station outlet pipe nodes. The initial flow rate Q0-SA of the SA0 pump station model node is 5 m3 / s, and the initial flow rate Q0-SB of the SB0 pump station model node is 5 m3 / s. A linkage logic between the pump station and the flap gate is established. When the flap gate is closed, the pump station operates during the river backflow period. Pump station PSA operates for 10 hours, and pump station PSB operates for 6 hours. In the figure, the white background with black border represents the divided drainage zones; the dots filled with black borders represent the river; the black solid lines represent the pipe network in the drainage zones; the vertical lines filled with black borders represent pump stations; and the black dashed lines represent the output pipes of the pump stations, including the intercepting pipe sections and the corresponding drainage pipes.

[0162] In this example, the rainfall recurrence period is defined as once every 100 years. The flood risk control standard is that the water depth exceeding 30 cm during rainfall in the drainage zone does not exceed 3 hours, and the surface water depth does not exceed 15 cm 2 hours after the water recedes. Under the initial pump station scale conditions, the flood risk in drainage zone SA0 was not controlled, while the flood risk in drainage zone SB0 was controlled. Therefore, the PSA flow rate of the pump station was subsequently increased, and the PSB flow rate of the pump station was decreased. The trial calculations were repeated until the flood risk in both drainage zones was just controlled under the corresponding pump station scale conditions. After adjustment, the PSA flow rate of the pump station was 6.4 m³ / s, operating for 10 hours; the PSB flow rate of the pump station was 4.2 m³ / s, operating for 6 hours. The trial calculation results of the surface runoff record model required for flood risk control according to Equation 1 are shown in the following table:

[0163] Table 1. Trial Calculation Table of Drainage Zoning Model for Typical Urban Flooding Risk

[0164]

[0165] Based on the trial calculation results of the runoff model for typical urban waterlogging risk drainage zones, the required flow for waterlogging risk control was estimated for the remaining drainage zones within runoff calculation groups A and B according to Equation 2, and the total runoff for urban waterlogging prevention and control was estimated. The results are shown in Table 2.

[0166] Table 2. Drainage Zone Model Estimation Table

[0167]

[0168] The estimated total runoff for urban flood control in this example is 1.61 million cubic meters.

[0169] To verify the reliability of the estimation results in this example, a two-dimensional integrated model was established in each of the nine drainage zones for simulation calculations, and the results were compared with the estimation results, as shown in Table 3:

[0170] Table 3. Drainage Zoning Model Estimation Table

[0171]

[0172] The results show that, in this example, compared with the hydraulic model trial algorithm, the urban waterlogging prevention and control runoff estimation method of the present invention has an error of -8.4% to 9.7% in the calculation results of each drainage zone and an error of 2.5% in the calculation results of the total runoff. The error range is within acceptable limits, and the urban waterlogging prevention and control runoff estimation method of the present invention can ensure the reliability of the runoff estimation results.

[0173] This invention provides a method for rapidly estimating the scale of runoff for urban-scale flood control. Based on a baseline survey of urban drainage and flood control and an assessment of flood risk, the method rationally divides runoff calculation groups by drainage zones as the calculation unit. Using the hydraulic model trial calculations of typical flood-prone drainage zones as a basis, the method performs a multi-factor weighted estimation of the runoff required for flood control within each runoff calculation group. Compared with traditional theoretical calculation methods and model trial methods, this method significantly simplifies the workload of urban-scale runoff estimation for flood control while ensuring reliability, reducing the corresponding manpower and time costs, thereby accelerating the overall progress and efficiency of related planning and design work.

[0174] From the perspectives of applicability, flexibility, and economy, this invention has strong application value in the planning, design, and construction of urban-scale drainage and flood control systems.

[0175] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for simulating runoff for urban flood control at the city scale, characterized in that, include: Step S1: Establish multiple drainage zones within the urban area, and select multiple typical drainage zones from the drainage zones; Step S2: Establish a drainage model for each of the typical drainage zones; The drainage model is used to characterize the drainage network, pumping stations, and waterways in the typical drainage zone. Step S3: Simulate rainfall events on the drainage model to obtain typical trial runoff for the typical drainage zone; Step S4: Generate the total runoff volume required for urban flood control in the urban area based on the typical trial runoff volume; Step S1 includes: Step S11: Divide the urban area into multiple drainage zones and obtain the background conditions of each drainage zone; Step S12: Set the drainage zones with similar background conditions into the same drainage zone group; Step S13: Select one typical drainage zone from each of the drainage zone groups; Step S3 includes: Step S31: Generate simulated rainfall events based on the designed rainfall pattern and the return period of the rainstorm, and set the initial flow rate value of the pumping station in the drainage model as the drainage flow rate; Step S32: Perform the simulated rainfall event on the drainage model to obtain drainage results; Step S33: Change the drainage flow rate, and then repeat step S32 to collect multiple drainage results and record the drainage flow rate corresponding to the drainage results; Step S34: Filter the drainage results and retain only the drainage results that do not pose a risk of waterlogging. Then select the minimum drainage flow rate among the drainage results as the trial flow rate of the pumping station. Step S35: Generate the typical trial runoff of the typical drainage zone based on the trial flow of the pumping station; Step S4 includes: Step S41: Based on the typical trial runoff, generate the estimated runoff for each drainage zone in the drainage zone group to which the typical drainage zone is located; Step S42: Based on the estimated runoff of the drainage zones, generate the group prevention runoff for each drainage zone group; Step S43: Based on the sum of the runoff volumes of all the groups, obtain the total runoff volume required for urban flood control in the urban area; Before performing step S35, a time-series calculation process is also included to obtain the pump station operating time and river backwater duration in the drainage results; The timing calculation process includes: Obtain each flap valve installed at the drainage outlet of the drainage network, and search for the drainage process corresponding to the drainage result based on the flap valve to obtain the closing time period of each flap valve; The closure period is taken as the duration of the river channel backwater and the operating time of the pumping station; In step S41, the method for generating the estimated runoff of the drainage zone based on the typical trial runoff includes: ； In the formula: Estimate the runoff volume for the drainage zone, in m³. 3 ; The typical trial runoff volume is given, in m³. 3 ; This represents the percentage of the risk area within the drainage zone. This represents the percentage of the risk area within the typical drainage zone. The area of ​​the drainage zone is expressed in km². 2 ; The area of ​​the typical drainage zone is given in km². 2 ; The duration of backwater in the typical drainage zone is expressed in hours. The duration of the backwater effect in the drainage zone is expressed in hours (h).

2. The method for simulating runoff for urban flood control according to claim 1, characterized in that, Step S2 includes: Step S21: Construct pipe network models and river models for the typical drainage zones respectively; Step S22: Construct a local ground model of the typical drainage zone based on the survey data of the typical drainage zone; Step S23: Add the pipeline model and the river model to the local ground model to generate the drainage model.

3. The method for simulating runoff for urban flood control according to claim 1, characterized in that, Before performing step S32, the method further includes: Step S301: Obtain the drainage outlets and intercepting pipe sections in the drainage model; Step S302: Set the upstream flow rate of the typical drainage zone according to the intercepting pipe section, and establish a binding relationship between the upstream flow rate and the drainage outlet of the pipeline network corresponding to the intercepting pipe section.

4. The method for simulating runoff for urban flood control according to claim 1, characterized in that, In step S35, the method for generating the typical calculated runoff based on the calculated flow rate of the pumping station includes: ； In the formula: The typical trial runoff volume is given, in m³. 3 ; The flow rate of the pumping station is calculated in m³. 3 / s; The pump station operating time during the simulated rainfall event is expressed in hours (h).

5. The method for simulating runoff for urban flood control according to claim 1, characterized in that, The baseline conditions include at least one of the following: regional area, topography, development level, river hydrological and hydraulic conditions, stormwater pipe density, stormwater pipe drainage capacity, stormwater drainage pumping station scale, and storage facility scale.

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