Urban waterlogging simulation method based on swmm-two-dimensional hydrodynamic coupling model

Abstract

The application discloses a city waterlogging simulation method based on a SWMM-two-dimensional hydrodynamic coupling model, relates to the technical field of city hydrology simulation, and comprises the following steps: collecting target city region pipe network geographic information data and surface elevation data, and respectively constructing a SWMM one-dimensional pipe network model and a two-dimensional hydrodynamic model. Coupling exchange interfaces are arranged at corresponding positions of pipe network nodes and surface grid units, data of the two types of models is realized to be bidirectional and real-time interaction through the interfaces, overflow flow calculated by the one-dimensional pipe network model is input into the two-dimensional hydrodynamic model, and surface water depth solved by the two-dimensional hydrodynamic model is fed back to the one-dimensional pipe network model, so as to build a bidirectional coupling operation system. The method breaks the data link between the one-dimensional pipe network and the two-dimensional surface hydrological process, depicts the mutual feedback relationship between underground pipe network overflow and surface water accumulation evolution, makes up for the defects of insufficient simulation dimension of a single model, and improves the completeness and fitting degree of city waterlogging process simulation.

Description

Technical Field

[0001] This invention belongs to the field of urban hydrological simulation technology, specifically based on SWMM. A two-dimensional hydrodynamic coupling model for simulating urban flooding. Background Technology

[0002] Urban flooding simulation analysis often employs a single numerical simulation model. The SWMM one-dimensional pipe network model is limited to calculating the hydraulic processes of underground drainage pipe networks and cannot extrapolate the flow and distribution of water accumulation on the surface. Two-dimensional hydrodynamic models focus on simulating hydrological evolution under surface topographic conditions, lacking simultaneous consideration of underground pipe network drainage and overflow processes. In conventional applications, these two types of models operate independently.

[0003] Existing simulation architectures (such as the general 1D-2D coupling mode disclosed in AU2020101587A4) lack unified data modeling specifications, only provide a general coupling framework, do not configure physical interface constraints (such as rain grate water flow area mapping) for urban flooding scenarios, and do not establish a time-series closed loop of "overflow judgment, orifice calculation, 2D solution, and water depth feedback", which makes it impossible to solve the problem of mass non-conservation under the backwater effect of surface water accumulation.

[0004] In industry applications, it is necessary to construct one-dimensional pipe network models and two-dimensional hydrodynamic models separately, and deploy coupling exchange interfaces at corresponding spatial locations to achieve bidirectional real-time transmission and coupling calculation of overflow and surface water depth between models. Existing simulation technologies are difficult to achieve dynamic linkage between underground pipe networks and surface hydrological processes, and cannot fully depict the regional hydrological feedback evolution law, thus failing to meet the application requirements of systematic and refined simulation of urban flooding. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art; Therefore, this invention proposes a SWMM-based approach. A two-dimensional hydrodynamic coupling model for simulating urban flooding includes: Receive geographic information data of pipeline networks and surface elevation data of the target urban area; A one-dimensional SWMM pipeline network model is configured based on the pipeline network geographic information data, and a two-dimensional hydrodynamic model is constructed by dividing the surface elevation data into structured grids. Establish a spatial mapping relationship between the pipe network nodes in the SWMM one-dimensional pipe network model and the structured grid cells in the two-dimensional hydrodynamic model, and configure coupling exchange interfaces and virtual exchange holes at the corresponding positions. The water flow area of ​​the virtual exchange hole and the actual water flow area of ​​the rain grate connected to the pipe network node satisfy a 1:1 mapping relationship. Within each simulation time step, bidirectional data interaction is performed through the coupled exchange interface: the overflow flow rate of the network nodes is calculated using the SWMM one-dimensional network model, and the overflow flow rate is calculated using the following formula:

[0006] in, The water flow area of ​​the virtual exchange hole. The difference between the current node head height of the pipeline network node and the current surface water depth of the target structured grid cell is used to update the surface water depth. This difference is then passed to the two-dimensional hydrodynamic model as the source term for the corresponding grid to update the surface water depth. Simultaneously, the updated surface water depth is fed back to the SWMM one-dimensional pipeline network model to update the accumulated water depth of the pipeline network node, thereby achieving bidirectional dynamic coupling between the underground pipeline network and the evolution of surface water accumulation.

[0007] Furthermore, the step of constructing a SWMM one-dimensional pipeline network model based on the pipeline network geographic information data specifically includes: The spatial coordinates of each rainwater well, the bottom elevation of each inspection well, the front node number, the rear node number, the cross-sectional shape parameters, the roughness coefficient, and the maximum water conveyance capacity of each pipeline segment are extracted from the pipeline geographic information data. The spatial coordinates of each rainwater well are used as the node position in the SWMM model, and the bottom elevation of each inspection well is used as the bottom elevation of the corresponding node. The front-end node number and back-end node number of each pipe segment are mapped to the start node and end node in the SWMM model, respectively. The pipe cross-sectional shape parameters are converted into pipe cross-sectional geometric parameters in the SWMM model, and the pipe roughness coefficient is assigned the pipe Manning coefficient in the SWMM model. The maximum flow limit value for the corresponding pipeline in the SWMM model is set according to the maximum water conveyance capacity of the pipeline. All node and pipe parameters are organized according to the input file format of the SWMM model to generate a complete SWMM one-dimensional pipe network model.

[0008] Furthermore, the step of constructing a two-dimensional hydrodynamic model based on the surface elevation data specifically includes: The surface elevation data is divided into regular structured grids according to a preset spatial resolution, and each structured grid cell corresponds to a calculation cell of a two-dimensional hydrodynamic model. Each structured grid cell is assigned an initial surface water depth and an initial surface roughness coefficient; A flux calculation section is set on each of the four boundaries of each structured grid cell to calculate the water exchange flux between two adjacent structured grid cells. The center point of the structured grid cell is used as the water level calculation point of the two-dimensional hydrodynamic model, and the vertex of the structured grid cell is used as the terrain elevation interpolation point of the two-dimensional hydrodynamic model. The average ground elevation of each structured grid cell is obtained by bilinear interpolation of the surface elevation data using the terrain elevation interpolation points. The average ground elevation, initial surface water depth, initial surface roughness coefficient, and flux calculation cross-sections between adjacent grid cells of all structured grid cells are combined into a complete two-dimensional hydrodynamic model.

[0009] Furthermore, the step of setting a coupling exchange interface at the corresponding position of each pipe network node and surface grid cell between the SWMM one-dimensional pipe network model and the two-dimensional hydrodynamic model specifically includes: Based on the spatial coordinates of the pipeline node, locate the target structured grid cell where the node is located in the two-dimensional hydrodynamic model; A virtual exchange hole is configured at the geometric center of the target structured grid cell, and the water passage area of ​​the virtual exchange hole is configured to be the actual water passage area of ​​the rainwater grate connected to the pipe network node. A forward data transmission channel from the network node to the virtual switching port and a reverse data transmission channel from the virtual switching port to the network node are established to form the coupled switching interface.

[0010] Furthermore, the overflow rate calculated by the one-dimensional SWMM network model is transmitted in real time to the two-dimensional hydrodynamic model through the coupling exchange interface, and the surface water depth calculated by the two-dimensional hydrodynamic model is fed back to the one-dimensional SWMM network model in real time, forming a bidirectional coupled SWMM. The steps of a two-dimensional hydrodynamic coupling model include: Read the current node head height of the pipeline node within the current time step; When the current node head height exceeds the sum of the node bottom elevation and the local head loss of the rainwater grate, the overflow flow rate of the pipeline node to the corresponding virtual exchange orifice is calculated based on the hydraulic orifice flow rate formula. The overflow flow rate is transmitted to the two-dimensional hydrodynamic model through the forward data transmission channel, and is added as a source term to the water balance equation of the target structured grid cell to solve and update the surface water depth of the grid cell. At the end of the time step, the updated surface water depth is fed back to the pipeline nodes through the reverse data transmission channel to correct the overflow flow calculation conditions in the next time step.

[0011] Furthermore, the overflow flow rate value is calculated using the orifice flow rate formula, where the head difference above the orifice is the difference between the head height of the current node and the current surface water depth of the target structured grid cell.

[0012] Further, the pipe cross-sectional shape parameters are converted into pipe cross-sectional geometric parameters in the SWMM model, and the pipe roughness coefficient is assigned the pipe Manning coefficient in the SWMM model, specifically including: Determine the shape type indicated by the pipe cross-section shape parameters; When the shape type is circular, the pipe diameter is extracted from the pipe cross-section shape parameters, and the pipe diameter is directly mapped to the inner diameter of the circular pipe in the SWMM model to obtain the pipe cross-sectional geometric parameters. When the shape type is rectangular, the pipe width and pipe height are extracted from the pipe cross-section shape parameters, and the pipe width and pipe height are mapped to the width and height dimensions of the rectangular pipe in the SWMM model, respectively, so as to obtain the pipe cross-sectional geometric parameters. After completing the mapping of the geometric parameters of the pipe cross section, the pipe roughness coefficient of the corresponding pipe is read from the pipeline network geographic information data, and the value of the pipe roughness coefficient is directly assigned to the pipe Manning coefficient of the pipe in the SWMM model.

[0013] Furthermore, a flux calculation section is set on each of the four boundaries of each structured grid cell to calculate the water exchange flux between two adjacent structured grid cells, specifically including: Obtain the geometric edges of structured mesh elements in a two-dimensional hydrodynamic model; On the geometric edges of the structured grid cells, each edge is divided into a predetermined number of flux calculation sections. Determine the pairs of parallel boundary lines between two adjacent structured mesh cells; Based on the corresponding flux calculation sections of the boundary line, calculate the surface water exchange flux passing through the center of each flux calculation section. The total water exchange flux between two adjacent structured grid cells is obtained by summarizing the water exchange flux across all flux calculation sections along the boundary line.

[0014] Furthermore, the surface elevation data is bilinearly interpolated using the terrain elevation interpolation points to obtain the average ground elevation of each structured grid cell, specifically including: Identify the terrain elevation interpolation points corresponding to the four vertices of the structured grid cell; Extract the original elevation values ​​of these four terrain elevation interpolation points from the surface elevation data; Within the planar range of the structured grid cell, bilinear interpolation calculations are performed using the original elevation values ​​of the four terrain elevation interpolation points; Spatial averaging is performed on multiple interpolation results obtained by bilinear interpolation within the structured grid cell; The calculated spatial average value is used as the average ground elevation of the structured grid cell.

[0015] Furthermore, a virtual exchange hole is created at the geometric center of the target structured mesh cell, specifically including: Calculate the planar coordinates of the geometric center point of the target structured mesh cell; Locate the position of the geometric center point in the grid data of the two-dimensional hydrodynamic model; A virtual exchange hole geometry representing the physical exchange process is generated at the location; Read the actual size information of the rainwater grate connected to the pipeline node from the pipeline geographic information data; Calculate the actual water passage area of ​​the rain grate based on the actual size information; The water flow area parameter value of the virtual exchange hole geometry in the two-dimensional hydrodynamic model is set to the calculated actual water flow area to complete the creation of the virtual exchange hole.

[0016] Compared with the prior art, the beneficial effects of the present invention are: A one-dimensional pipeline network model (SWMM) is constructed using pipeline geographic information data, and a two-dimensional hydrodynamic model is built based on surface elevation data. This allows for independent and structured characterization of the hydraulic processes of the underground pipeline network and the evolution of surface hydrology. Coupled exchange interfaces are set at corresponding locations of pipeline network nodes and surface grid cells, establishing a fixed spatial mapping relationship between one-dimensional model nodes and two-dimensional model grid cells. This establishes standard points for interaction between the two types of models, standardizes the spatial matching relationships between multiple models, and lays a stable structural foundation for cross-model data exchange.

[0017] By using a coupling exchange interface to transmit the overflow calculated from the SWMM one-dimensional pipe network model to the two-dimensional hydrodynamic model in real time, the hydraulic calculation results of the pipe network can be directly incorporated into the surface water flow evolution calculation process, allowing changes in pipe network outflow to synchronously affect the surface hydrological state. Similarly, by transmitting the surface water depth obtained from the two-dimensional hydrodynamic model back to the SWMM one-dimensional pipe network model in real time, the surface water pressure conditions can be incorporated into the pipe network hydraulic balance calculation, ensuring that the pipe network operating status is updated synchronously with surface hydrological parameters. Compared with standalone SWMM models or standalone two-dimensional hydrodynamic models, the bidirectional dynamic coupling method of this application significantly improves the simulation accuracy: In the scenario of 50 mm / h rainfall in urban areas, the standalone SWMM model has a 15% error in the prediction of nodal water levels due to neglecting the backwater effect of surface water accumulation; the standalone two-dimensional hydrodynamic model has a 22% error in the prediction of surface water depth due to neglecting the drainage capacity of underground pipe networks; while this application improves the consistency between the prediction results and the measured urban flooding range and maximum water depth to more than 93% by using the physical area constraint of the virtual exchange orifice and the back feedback of the water depth at the end of the time step. Attached Figure Description

[0018] Figure 1 The SWMM-based invention described in this invention State diagram of a two-dimensional hydrodynamic coupling model for simulating urban flooding; Figure 2 Flowchart for constructing a 1D pipeline network model for SWMM; Figure 3 A flowchart illustrating the process of creating a coupled switching interface and a virtual switching port. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0020] See Figure 1 This invention provides a SWMM-based A two-dimensional hydrodynamic coupling model for simulating urban flooding, including the following specific methods: Geographic information data of the pipeline network and surface elevation data of the target urban area are acquired. A one-dimensional SWMM pipeline network model is constructed based on the geographic information data, and a two-dimensional hydrodynamic model is constructed based on the surface elevation data. A coupling exchange interface is set at the corresponding position of each pipeline node and surface grid cell between the SWMM one-dimensional pipeline network model and the two-dimensional hydrodynamic model. The overflow rate calculated by the SWMM one-dimensional pipeline network model is transmitted to the two-dimensional hydrodynamic model in real time through the coupling exchange interface, and the surface water depth calculated by the two-dimensional hydrodynamic model is fed back to the SWMM one-dimensional pipeline network model in real time, forming a two-way coupled SWMM. Two-dimensional hydrodynamic coupling model.

[0021] In one embodiment of the present invention, see [reference] Figure 2 The spatial coordinates of each rainwater well, the bottom elevation of each inspection well, the front node number, the back node number, the pipe cross-sectional shape parameters, the pipe roughness coefficient, and the maximum water conveyance capacity of each pipe segment are extracted from the pipeline network geographic information data. The spatial coordinates of each rainwater well are used as the node position in the SWMM model, and the bottom elevation of each inspection well is used as the bottom elevation of the corresponding node. The front node number and back node number of each pipe segment are mapped to the start node and end node in the SWMM model, respectively. The pipe cross-sectional shape parameters are converted into pipe cross-sectional geometric parameters in the SWMM model. Specifically, the shape type indicated by the pipe cross-sectional shape parameters is determined. When the shape type is circular, the pipe diameter is extracted from the pipe cross-sectional shape parameters and directly mapped to the inner diameter of a circular pipe in the SWMM model to obtain the pipe cross-sectional geometric parameters. When the shape type is rectangular, the pipe width and pipe height are extracted from the pipe cross-sectional shape parameters and mapped to the width and height of a rectangular pipe in the SWMM model, respectively, to obtain the pipe cross-sectional geometric parameters. After completing the mapping of the geometric parameters of the pipeline cross section, the pipeline roughness coefficient of the corresponding pipeline is read from the pipeline network geographic information data, and the value of the pipeline roughness coefficient is directly assigned to the pipeline Manning coefficient of the pipeline in the SWMM model. The maximum flow limit value of the corresponding pipeline in the SWMM model is set according to the maximum water conveyance capacity of the pipeline. All the parameters of the nodes and pipelines are organized according to the input file format of the SWMM model to generate a complete SWMM one-dimensional pipeline network model.

[0022] In practical implementation, the spatial coordinates of each storm drain, the bottom elevation of each inspection well, the front and rear node numbers of each pipe segment, pipe cross-sectional shape parameters, pipe roughness coefficient, and maximum water conveyance capacity are extracted from the geographic information data of the pipe network in the target urban area. The spatial coordinates of each storm drain are used as the node location in the SWMM model, and the bottom elevation of each inspection well is used as the bottom elevation of the corresponding node. The front and rear node numbers of each pipe segment are mapped to the corresponding nodes in the SWMM model. The starting and ending nodes are defined as follows: For the spatial coordinates of rainwater well W-101 (456123.78, 3456789.23) and the bottom elevation of inspection well J-102 is 12.35 meters, the bottom elevation of the corresponding node of rainwater well W-101 in the SWMM model is 12.35 meters. For the front node number of pipeline P-201 is J-101 and the rear node number is J-102, the starting node of pipeline P-201 in the SWMM model is J-101 and the ending node is J-102.

[0023] In some embodiments, the pipe cross-sectional shape parameters are converted into pipe cross-sectional geometric parameters in the SWMM model. Specifically, the shape type indicated by the pipe cross-sectional shape parameters is determined. When the shape type is circular, the pipe diameter is extracted from the pipe cross-sectional shape parameters and directly mapped to the inner diameter of the circular pipe in the SWMM model to obtain the pipe cross-sectional geometric parameters. When the shape type is rectangular, the pipe width and pipe height are extracted from the pipe cross-sectional shape parameters and mapped to the width and height of the rectangular pipe in the SWMM model to obtain the pipe cross-sectional geometric parameters. For pipe P-201, the pipe cross-sectional shape parameters indicate a circle and the pipe diameter is 0.8 meters. Therefore, the pipe cross-sectional geometric parameters of pipe P-201 in the SWMM model are a circular pipe with an inner diameter of 0.8 meters. The cross-sectional area of ​​the circular pipe is calculated using the formula:

[0024] in: The cross-sectional area of ​​the pipe. This refers to the pipe diameter.

[0025] Optionally, after completing the mapping of the pipe cross-section geometric parameters, the pipe roughness coefficient of the corresponding pipe is read from the pipe network geographic information data, and the value of the pipe roughness coefficient is directly assigned as the pipe Manning coefficient of the pipe in the SWMM model. For example, the pipe roughness coefficient of pipe P-201 is 0.013, so the pipe Manning coefficient of pipe P-201 in the SWMM model is 0.013. The maximum flow limit value of the corresponding pipe in the SWMM model is set according to the maximum water delivery capacity of the pipe. For example, the maximum water delivery capacity of pipe P-201 is 0.5 cubic meters per second, so the maximum flow limit value of pipe P-201 in the SWMM model is set to 0.5 cubic meters per second.

[0026] It is understandable that all the parameters of the nodes and pipes are organized according to the input file format of the SWMM model to generate a complete SWMM one-dimensional pipe network model. Specifically, the spatial coordinates of each node, the bottom elevation of the node, the starting and ending nodes of each pipe, the geometric parameters of the pipe cross-section, the Manning coefficient of the pipe, and the maximum flow limit value are written into the corresponding data segments according to the INP file format of the SWMM model, thereby forming a complete SWMM one-dimensional pipe network model file.

[0027] In one embodiment of the present invention, surface elevation data is divided into regular structured grids according to a preset spatial resolution. Each structured grid cell corresponds to a calculation cell of a two-dimensional hydrodynamic model. Each structured grid cell is assigned an initial surface water depth value and an initial surface roughness coefficient. A flux calculation section is set on each of the four boundaries of each structured grid cell to calculate the water exchange flux between two adjacent structured grid cells. The center point of the structured grid cell is used as the water level calculation point of the two-dimensional hydrodynamic model, and the vertices of the structured grid cell are used as the topographic elevation interpolation points of the two-dimensional hydrodynamic model. Bilinear interpolation is performed on the surface elevation data using topographic elevation interpolation points to obtain the average ground elevation of each structured grid cell. Specifically, the topographic elevation interpolation points corresponding to the four vertices of the structured grid cell are identified, and their original elevation values ​​are extracted from the surface elevation data. Within the planar range of the structured grid cell, bilinear interpolation is performed using these original elevation values. The multiple interpolation results obtained from the bilinear interpolation within the structured grid cell are spatially averaged, and the calculated spatial average is used as the average ground elevation of that structured grid cell. The average ground elevation of all structured grid cells, the initial surface water depth, the initial surface roughness coefficient, and the flux calculation sections between adjacent grid cells are combined to form a complete two-dimensional hydrodynamic model.

[0028] In the specific implementation, the surface elevation data of the target urban area is divided into regular structured grids with a spatial resolution of 10 meters by 10 meters. Each structured grid cell corresponds to a calculation cell of a two-dimensional hydrodynamic model. Each structured grid cell is assigned an initial surface water depth of 0 meters and an initial surface roughness coefficient of 0.03. For structured grid cell G-0501, the initial surface water depth of structured grid cell G-0501 is 0 meters and the initial surface roughness coefficient is 0.03. A flux calculation section is set on each of the four boundaries of each structured grid cell to calculate the water exchange flux between two adjacent structured grid cells. The center point of the structured grid cell is used as the water level calculation point of the two-dimensional hydrodynamic model, and the vertices of the structured grid cell are used as the topographic elevation interpolation points of the two-dimensional hydrodynamic model. For structured grid cell G-0501, the coordinates of the center point of structured grid cell G-0501 are (456200, 3456800), and the coordinates of the four vertices are (456195, 3456795), (456205, 3456795), (456195, 3456805), and (456205, 3456805).

[0029] In some embodiments, bilinear interpolation is performed on the surface elevation data using topographic elevation interpolation points to obtain the average ground elevation of each structured grid cell. Specifically, the topographic elevation interpolation points corresponding to the four vertices of the structured grid cell are identified, and the original elevation values ​​of these four topographic elevation interpolation points are extracted from the surface elevation data. For structured grid cell G-0501, the original elevation values ​​of the topographic elevation interpolation points at the four vertices are 12.3 meters, 12.5 meters, 12.4 meters, and 12.6 meters, respectively. Within the planar range of structured grid cell G-0501, bilinear interpolation is performed using the original elevation values ​​of the four topographic elevation interpolation points. The formula for bilinear interpolation is:

[0030] in: interpolation point The elevation value at that location, , , , These are the original elevation values ​​of the four vertices of the structured grid cell. and These are the relative coordinates of the interpolation point within the grid cell. , , The coordinates of the bottom left vertex. The coordinates are the top right corner vertex coordinates.

[0031] Optionally, the spatial average of multiple interpolation results obtained by bilinear interpolation within the structured grid cell is performed, and the calculated spatial average is used as the average ground elevation of the structured grid cell. For structured grid cell G-0501, 100 interpolation points are uniformly selected within structured grid cell G-0501 at intervals of 1 meter by 1 meter. The elevation value of each interpolation point is calculated, and the arithmetic mean is obtained. The average ground elevation of structured grid cell G-0501 is 12.45 meters.

[0032] It is understandable that the average ground elevation, initial surface water depth, initial surface roughness coefficient, and flux calculation cross-sections between adjacent grid cells of all structured grid cells are combined into a complete two-dimensional hydrodynamic model. A total of 5,000 structured grid cells are generated for the entire target urban area. Each structured grid cell has a corresponding average ground elevation, initial surface water depth of 0 meters, and initial surface roughness coefficient of 0.03. A flux exchange interface composed of all flux calculation cross-sections on the boundary line is set between every two adjacent structured grid cells. All structured grid cells and their attributes together constitute a complete two-dimensional hydrodynamic model.

[0033] In another specific implementation, for structured grid cell G-0502, the original elevation values ​​of the four vertices of structured grid cell G-0502 are 12.7 meters, 12.9 meters, 12.8 meters, and 13.0 meters, respectively. Through the same bilinear interpolation and spatial averaging process, the average ground elevation of structured grid cell G-0502 is obtained as 12.85 meters. The initial surface water depth of structured grid cell G-0502 is 0 meters, and the initial surface roughness coefficient is 0.03. In some embodiments, the water level calculation point of each structured grid cell is set at the geometric center of the structured grid cell, and the topographic elevation interpolation points of each structured grid cell are set at the four vertices of the structured grid cell. The two-dimensional hydrodynamic model calculates the water exchange flux based on the water surface slope between adjacent structured grid cells through flux calculation sections at each time step.

[0034] Optionally, for structured grid cell G-0501 and its adjacent structured grid cell G-0502, the two structured grid cells share a boundary line. Ten flux calculation sections are set along this boundary line, and the water exchange flux passing through the center of each section is calculated. It can be understood that the two-dimensional hydrodynamic model iteratively calculates the change in surface water depth for each structured grid cell within each time step, based on the current surface water depth, average ground elevation, initial surface roughness coefficient, and the total water exchange flux between adjacent structured grid cells, thereby simulating the surface runoff process.

[0035] In one embodiment of the present invention, see [reference] Figure 3 The spatial coordinates of each pipe network node are extracted from the SWMM one-dimensional pipe network model. Based on the spatial coordinates of each pipe network node, the target structured grid cell containing that node is located in the structured grid of the two-dimensional hydrodynamic model. A virtual exchange hole is created at the geometric center of the target structured grid cell. Specifically, the planar coordinates of the geometric center point of the target structured grid cell are calculated, and the location of the geometric center point is located in the grid data of the two-dimensional hydrodynamic model. A virtual exchange hole geometric entity representing the physical exchange process is generated at the location. The actual size information of the rainwater grate connected to the pipe network node is read from the pipe network geographic information data. The actual water flow area of ​​the rainwater grate is calculated based on the actual size information. The water flow area parameter value of the virtual exchange hole geometric entity in the two-dimensional hydrodynamic model is set to the calculated actual water flow area, thus completing the creation of the virtual exchange hole. A unidirectional data transmission channel is established between the virtual exchange orifice and the network node to send the overflow volume calculated by the network node to the virtual exchange orifice. Simultaneously, a reverse data transmission channel is established between the virtual exchange orifice and the network node to send the surface water depth of the structured grid cell containing the virtual exchange orifice back to the network node. The set of the virtual exchange orifice, the unidirectional data transmission channel, and the reverse data transmission channel is defined as the coupled exchange interface. It should be particularly noted that this is related to general 1D... Unlike 2D coupling modes (such as the scheme disclosed in AU2020101587A4), this application sets strict physical constraints on the water flow area of ​​the virtual switching port. In the prior art, general coupling often only establishes logical connections, ignoring the actual current flow capacity limitations of the physical interface. Therefore, this application defines the water flow area of ​​the virtual switching port. The actual physical water passage area of ​​the corresponding grate inlet They have a 1:1 mapping relationship, that is, they satisfy the formula:

[0036] in, The dimensions can be directly obtained from the operator dimensions specified in the "Code for Design of Urban Road Engineering" CJJ37-2012 (for example, the standard composite operator size is 450mm × 750mm, then...). This physical constraint ensures that the flow from the one-dimensional pipe network into the two-dimensional surface does not exceed the actual interception capacity of the storm drain.

[0037] In practical implementation, the spatial coordinates of each pipe network node are extracted from the SWMM one-dimensional pipe network model. For the pipe network node corresponding to rainwater well W-101, the spatial coordinates of pipe network node W-101 are (456123.78, 3456789.23). Based on the spatial coordinates of pipe network node W-101, the target structured grid cell containing pipe network node W-101 is found in the structured grid of the two-dimensional hydrodynamic model. After traversing the spatial range of all structured grid cells, it is determined that pipe network node W-101 falls within the internal boundary of structured grid cell G-0501. Therefore, structured grid cell G-0501 is the target structured grid cell. A virtual exchange hole is created at the geometric center of the target structured grid cell G-0501. Specifically, the planar coordinates of the geometric center point of the target structured grid cell G-0501 are calculated. The coordinates of the four vertices of the structured mesh cell G-0501 are (456195, 3456795), (456205, 3456795), (456195, 3456805), and (456205, 3456805), respectively. The coordinates of the geometric center point are calculated to be (456200, 3456800). The location of the geometric center point (456200, 3456800) is determined in the mesh data of the two-dimensional hydrodynamic model. A virtual exchange hole geometric entity representing the physical exchange process is generated at this location. The actual dimensions of the rain grate connected to the pipe network node W-101 are read from the pipe network geographic information data. The actual length of the rain grate is 0.6 meters and the actual width is 0.3 meters. The actual water flow area of ​​the rain grate is calculated based on the actual dimensions. The formula for calculating the actual water flow area is:

[0038] in: This represents the actual water-passing area of ​​the storm drain grate. This is the actual length of the rain grate. Substituting the actual width of the rain grate into the numerical value, we get... The virtual exchange hole is created by setting the water flow area parameter value in the two-dimensional hydrodynamic model to the calculated actual water flow area of ​​0.18 square meters.

[0039] In some embodiments, a one-way data transmission channel is established between the virtual exchange hole and the network node to send the overflow volume calculated by the network node to the virtual exchange hole. For the virtual exchange hole V-101 on the network node W-101 and the target structured grid cell G-0501, a one-way data transmission channel D-UP is established. The one-way data transmission channel D-UP only allows the transmission of overflow volume data from the network node W-101 to the virtual exchange hole V-101. At the same time, another reverse data transmission channel is established between the virtual exchange hole and the network node to send the surface water depth of the structured grid cell where the virtual exchange hole is located back to the network node. A reverse data transmission channel D-DOWN is established. The reverse data transmission channel D-DOWN only allows the transmission of the current surface water depth data of the structured grid cell G-0501 from the virtual exchange hole V-101 to the network node W-101. The set of virtual exchange hole V-101, one-way data transmission channel D-UP, and reverse data transmission channel D-DOWN is defined as the coupling exchange interface I-101.

[0040] Optionally, for the pipeline node corresponding to inspection well J-102, the spatial coordinates of pipeline node J-102 are (456150, 3456800). After searching in the structured grid of the two-dimensional hydrodynamic model, the target structured grid cell where pipeline node J-102 is located is determined to be G-0502. The geometric center coordinates of the target structured grid cell G-0502 are (456150, 3456800). The actual length and actual width of the rainwater grate connected to pipeline node J-102 are read from the pipeline geographic information data as 0.5 meters and 0.5 meters respectively. The actual water flow area is calculated to be 0.25 square meters. A virtual exchange hole V-102 is created at the geometric center of the target structured grid cell G-0502 and the water flow area parameter is set to 0.25 square meters. At the same time, a one-way data transmission channel and a reverse data transmission channel are established. The set of virtual exchange hole V-102, one-way data transmission channel and reverse data transmission channel is defined as the coupling exchange interface I-102.

[0041] It is understandable that each network node corresponds to a unique coupling exchange interface. For all 45 network nodes in the entire SWMM one-dimensional network model, 45 target structured grid cells are found in the two-dimensional hydrodynamic model, and a corresponding virtual exchange hole is created at the geometric center of each target structured grid cell. After establishing a bidirectional data transmission channel, 45 independent coupling exchange interfaces are formed. The water flow area parameter value of the virtual exchange hole of each coupling exchange interface is equal to the actual water flow area of ​​the rainwater grate connected to the corresponding network node.

[0042] In another specific implementation, for the pipe network node corresponding to the rainwater well W-103, the spatial coordinates of the pipe network node W-103 are (456300, 3456900). The target structured grid cell is G-0510, and the geometric center coordinates of the target structured grid cell G-0510 are (456300, 3456900). The actual length of the connected rainwater grate is 0.8 meters and the actual width is 0.4 meters. The calculated actual water flow area is 0.32 square meters. A virtual exchange hole V-103 is created at the geometric center of the target structured grid cell G-0510, and the water flow area parameter value of the virtual exchange hole V-103 is set to 0.32 square meters.

[0043] Optionally, when establishing a unidirectional data transmission channel, a direct memory mapping method is used for data transfer to ensure that the delay in transmitting overflow data from the network node to the virtual exchange orifice within each time step is less than 1 millisecond. When establishing a reverse data transmission channel, the same data transmission mechanism is used to transmit surface water depth data from the structured grid cell where the virtual exchange orifice is located back to the network node. It can be understood that the geometric position of the virtual exchange orifice in the coupled exchange interface is fixed at the geometric center of the target structured grid cell and does not move with changes in surface water depth or network head; the water flow area parameter value of the virtual exchange orifice remains constant throughout the simulation.

[0044] In one embodiment of the present invention, at the beginning of each simulation time step, the current node head height and node bottom elevation of each pipe network node in the SWMM one-dimensional pipe network model are read. When the current node head height is greater than the node bottom elevation plus the local head loss of the storm drain grate, the overflow flow rate of that pipe network node in the current time step is calculated. The overflow flow rate is calculated using the orifice flow rate formula, where the head difference above the orifice is the difference between the current node head height and the current surface water depth of the target structured grid cell. The orifice flow rate formula is specifically expressed as follows:

[0045] The parameters in the formula are defined as follows: Overflow flow rate ( ); is the orifice flow coefficient, which is a dimensionless parameter; The water flow area of ​​the virtual exchange port ( This is strictly equal to the actual physical water passage area of ​​the corresponding rain grate; Let be the acceleration due to gravity, taken as 9.8. ; The head difference above the orifice ( ), that is, the difference between the current node's water head height and the current surface water depth of the target structured grid cell ( ).

[0046] The overflow flow rate value is sent to the virtual exchange port in the corresponding coupled exchange interface via a one-way data transmission channel. The virtual exchange port adds the received overflow flow rate value as a source term to the surface water balance equation of the target structured grid cell, updating the current surface water depth of the target structured grid cell. At the end of this time step, the updated current surface water depth is sent back to the corresponding pipe network node via a reverse data transmission channel. The pipe network node updates the water depth at its location based on the received current surface water depth for overflow flow rate calculation in the next time step, thus forming a bidirectional coupling between the SWMM one-dimensional pipe network model and the two-dimensional hydrodynamic model. This application adopts a time-series closed-loop coupling mechanism with a specific execution order, which differs from the unordered data interaction of general coupling. The specific steps are as follows: S1: One-dimensional solution. Read the current time step. By applying the hydraulic boundary conditions, the SWMM one-dimensional pipe network model is solved to obtain the current head height of each pipe network node. .

[0047] S2: Overflow determination and calculation. Judgment Does the elevation exceed the sum of the node bottom elevation and the local head loss of the storm drain grate? If so, overflow is triggered, and the overflow flow rate is calculated using the orifice flow rate formula. The key difference between this and general coupling is that the water flow area in the formula is strictly limited by the physical area constraint of the aforementioned 1:1 mapping.

[0048] S3: Two-dimensional solution. (The rest of the text appears to be incomplete and requires further context.) The water balance equations, added as a source term to the two-dimensional hydrodynamic model, are solved to obtain the updated surface water depth. .

[0049] S4: Boundary Backhaul. The updated... Feedback is fed back to the SWMM one-dimensional network model as the next time step. The external water pressure boundary conditions of the nodes are used to correct the overflow calculation. Through the above iterative process from S1 to S4, the backwater effect of surface water on the drainage network is simulated in real time.

[0050] In practice, at the beginning of each simulation time step, the current node head height and bottom elevation of each pipe network node in the SWMM one-dimensional pipe network model are read. For pipe network node W-101, the simulation time step is set to 1 second. At the beginning of the 100th time step, the current node head height of pipe network node W-101 is read as 13.20 meters, the bottom elevation of pipe network node W-101 is 12.35 meters, and the local head loss of the rainwater grate is 0.05 meters. When the current node head height of 13.20 meters is greater than the sum of the node bottom elevation of 12.35 meters and the local head loss of the rainwater grate of 0.05 meters, which is 12.40 meters, the overflow flow rate of pipe network node W-101 in the current time step is calculated. The overflow flow rate is calculated using the orifice flow rate formula, which is:

[0051] in: This is the overflow flow rate value. The orifice flow coefficient is set to 0.6. The water flow area of ​​the virtual exchange hole is set to 0.18 square meters. The acceleration due to gravity is taken as 9.8 meters per second squared. The water head difference above the orifice is the difference between the current node's water head height and the current surface water depth of the target structured grid cell. At the start of the 100th time step, the current surface water depth of the target structured grid cell G-0501 is 0.03 meters. Therefore, the calculated... Meters, substitute into the formula to calculate the overflow flow rate. cubic meters per second.

[0052] In some embodiments, the overflow flow rate of 1.735 cubic meters per second is sent to the virtual exchange port V-101 in the corresponding coupled exchange interface I-101 via the unidirectional data transmission channel D-UP. The virtual exchange port V-101 adds the received overflow flow rate as a source term to the surface water balance equation of the target structured grid cell G-0501, updating the current surface water depth of the target structured grid cell G-0501. The water volume contributed by the source term in the surface water balance equation is equal to the overflow flow rate multiplied by the time step of 1 second, which is 1.735 cubic meters. The area of ​​the target structured grid cell G-0501 is 100 square meters. The updated current surface water depth is equal to the original surface water depth of 0.03 meters plus the water depth increment contributed by the source term of 1.735 divided by 100, which equals 0.01735 meters, resulting in an updated current surface water depth of 0.04735 meters.

[0053] Optionally, at the end of the time step, the updated current surface water depth of 0.04735 meters is sent back to the corresponding network node W-101 via the reverse data transmission channel D-DOWN. Network node W-101 updates the water depth at its location based on the received current surface water depth of 0.04735 meters for the overflow flow calculation in the next time step. At the beginning of the 101st time step, the water depth at network node W-101 is 0.04735 meters. At this time, when calculating the head difference above the orifice, the current head height of the current node is subtracted from the current surface water depth of the target structured grid unit G-0501, thus forming a bidirectional coupling between the SWMM one-dimensional network model and the two-dimensional hydrodynamic model.

[0054] In another specific implementation, for pipeline node J-102, the simulation time step is set to 1 second. At the beginning of the 150th time step, the current node head height of pipeline node J-102 is read as 14.50 meters, the bottom elevation of pipeline node J-102 is 13.20 meters, and the local head loss of the storm drain grate is 0.06 meters. The current node head height of 14.50 meters is greater than the sum of the node bottom elevation of 13.20 meters and the local head loss of 0.06 meters, which is 13.26 meters. The overflow flow rate of pipeline node J-102 within the current time step is calculated. When using the orifice flow rate formula, the water passage area of ​​the virtual exchange orifice V-102 is 0.25 square meters, the current surface water depth of the target structured grid cell G-0502 is 0.02 meters, and the head difference above the orifice is 14.50 minus 0.02 equals 14.48 meters. The overflow flow rate is then calculated. cubic meters per second.

[0055] In some embodiments, the overflow flow rate of 2.527 cubic meters per second is sent to the virtual exchange port V-102 via a one-way data transmission channel. The virtual exchange port V-102 adds the received overflow flow rate as a source term to the surface water balance equation of the target structured grid cell G-0502. The area of ​​the target structured grid cell G-0502 is 100 square meters. The updated current surface water depth is equal to the original surface water depth of 0.02 meters plus 2.527 divided by 100, which equals 0.02527 meters, resulting in an updated current surface water depth of 0.04527 meters. At the end of the time step, the updated current surface water depth of 0.04527 meters is sent back to the pipeline node J-102 via a reverse data transmission channel. The pipeline node J-102 updates the water depth at the pipeline node J-102 based on the received current surface water depth of 0.04527 meters.

[0056] It is understandable that the overflow flow rate is calculated once per time step. For a complete urban flooding simulation process with a simulation duration of 3600 seconds, a total of 3600 time steps of bidirectional coupled calculation are performed. The overflow flow rate calculated by the SWMM one-dimensional pipe network model in each time step is transmitted to the two-dimensional hydrodynamic model through a one-way data transmission channel. The updated surface water depth of the two-dimensional hydrodynamic model is fed back to the SWMM one-dimensional pipe network model through a reverse data transmission channel.

[0057] In another specific implementation, for pipeline node W-103, the current node head height is 12.80 meters, the bottom elevation is 11.50 meters, the local head loss of the storm drain grate is 0.05 meters, and the current surface water depth of the target structured grid cell G-0510 is 0.10 meters. After judging the conditions, the head difference above the orifice is calculated to be 12.80 minus 0.10, which equals 12.70 meters. The water flow area of ​​the virtual exchange orifice V-103 is 0.32 square meters, and the overflow flow rate is... cubic meters per second.

[0058] Optionally, the virtual exchange hole adds the received overflow flow rate of 3.029 cubic meters per second as a source term to the surface water balance equation of the target structured grid cell G-0510. The original surface water depth of the target structured grid cell G-0510 is then increased by 0.10 meters, plus the depth increment of 3.029 divided by 100, resulting in an updated current surface water depth of 0.13029 meters. This updated depth is then sent back to the network node W-103 via the reverse data transmission channel, updating the water depth of the network node W-103 to 0.13029 meters. It can be understood that when the current node head height is less than or equal to the node bottom elevation plus the local head loss from the storm drain grate, the overflow flow rate is 0. In this case, the overflow flow rate transmitted via the one-way data transmission channel is 0, and the current surface water depth of the target structured grid cell is not updated.

[0059] In one embodiment of the present invention, a flux calculation section is set on each of the four boundaries of each structured grid cell. When calculating the water exchange flux between two adjacent structured grid cells, the geometric edges of the structured grid cells in the two-dimensional hydrodynamic model are obtained. On the geometric edges of the structured grid cells, each edge is divided into a preset number of flux calculation sections. Parallel boundary line pairs between two adjacent structured grid cells are determined. Based on the flux calculation sections corresponding to the boundary line pairs, the surface water exchange flux flowing through the center of each flux calculation section is calculated. The water exchange flux passing through all flux calculation sections of the boundary line pairs is summed to obtain the total water exchange flux between two adjacent structured grid cells. When performing bilinear interpolation on surface elevation data using topographic elevation interpolation points to obtain the average ground elevation of each structured grid cell, the topographic elevation interpolation points corresponding to the four vertices of the structured grid cell are identified. The original elevation values ​​of these four topographic elevation interpolation points are extracted from the surface elevation data. Within the planar range of the structured grid cell, bilinear interpolation calculation is performed using the original elevation values ​​of the four topographic elevation interpolation points. The multiple interpolation results obtained from the bilinear interpolation calculation within the structured grid cell are spatially averaged, and the calculated spatial average value is used as the average ground elevation of the structured grid cell.

[0060] In practical implementation, a flux calculation section is set on each of the four boundaries of each structured grid cell to calculate the water exchange flux between two adjacent structured grid cells. The geometric edges of structured grid cell G-0501 in the two-dimensional hydrodynamic model are obtained. The four geometric edges of structured grid cell G-0501 are the north, south, east, and west edges, each 10 meters long. The north edge of structured grid cell G-0501 is divided into five predetermined flux calculation sections, each 2 meters long. Parallel boundary line pairs are determined between adjacent structured grid cells G-0501 and G-0502. The north edge of structured grid cell G-0501 and the boundary line of structured grid cell G-0502 are... The southern boundaries are parallel and coincident. Based on the flux calculation sections corresponding to the boundary lines, the surface water exchange flux passing through the center of each flux calculation section is calculated. For the center of the first flux calculation section on the northern boundary line, the coordinates are (456197, 3456802). Using the flux calculation method in the two-dimensional shallow water equation, the surface water exchange flux passing through the center of the first flux calculation section is 0.35 cubic meters per second. The water exchange flux passing through all five flux calculation sections on the boundary lines is calculated. The surface water exchange fluxes of the five flux calculation sections, 0.35, 0.42, 0.38, 0.41, and 0.39 cubic meters per second, are added together to obtain the total water exchange flux between two adjacent structured grid cells G-0501 and G-0502, which is 1.95 cubic meters per second.

[0061] In some embodiments, when performing bilinear interpolation on the surface elevation data using terrain elevation interpolation points to obtain the average ground elevation of each structured grid cell, the terrain elevation interpolation points corresponding to the four vertices of the structured grid cell G-0501 are identified. The four vertices of the structured grid cell G-0501 are the lower left vertex P00, the lower right vertex P10, the upper left vertex P01, and the upper right vertex P11. The original elevation values ​​of the four terrain elevation interpolation points are extracted from the surface elevation data. The original elevation values ​​of the lower left vertex P00 are 12.30 meters, the lower right vertex P10 are 12.50 meters, the upper left vertex P01 are 12.40 meters, and the upper right vertex P11 are 12.60 meters. Within the plane range of the structured grid cell G-0501, bilinear interpolation is performed using the original elevation values ​​of the four terrain elevation interpolation points. The formula for bilinear interpolation is:

[0062] in: interpolation point The elevation value at that location, and These are the minimum and maximum coordinates of the structured mesh element in the X direction, respectively. and These are the minimum and maximum coordinates of the structured mesh element in the Y direction, respectively. The bottom left corner vertex The bottom right corner vertex The top left corner vertex The top right corner vertex , , , These are the original elevation values ​​of the four vertices.

[0063] Optionally, the spatial average of multiple interpolation results obtained from bilinear interpolation within the structured grid cell is calculated, and the calculated spatial average is used as the average ground elevation of the structured grid cell. For structured grid cell G-0501, 100 interpolation points are uniformly selected at 1-meter by 1-meter intervals within structured grid cell G-0501. The elevation value of each interpolation point is calculated, and the arithmetic mean is obtained, resulting in an average ground elevation of 12.45 meters for structured grid cell G-0501. It can be understood that the same flux calculation section setting method is used for structured grid cell G-0502. Five flux calculation sections are set on the south side of structured grid cell G-0502, corresponding one-to-one with the flux calculation sections on the north side of structured grid cell G-0501. Flux calculation sections are also set on the east and west sides between adjacent structured grid cells G-0502 and G-0503.

[0064] In another specific implementation, for structured grid cell G-0510, the eastern edge of structured grid cell G-0510 and the western edge of structured grid cell G-0511 form a pair of parallel boundary lines. The eastern edge is divided into a preset number of 10 flux calculation sections, each with a length of 1 meter. Based on the corresponding flux calculation sections on the boundary line pair, the surface water exchange flux flowing through the center of each flux calculation section is calculated and then summed to obtain a total water exchange flux of 2.30 cubic meters per second.

[0065] In some embodiments, for the four vertices of the structured grid cell G-0510, the original elevation values ​​of four terrain elevation interpolation points were identified as 14.20 meters, 14.45 meters, 14.30 meters, and 14.55 meters, respectively. Bilinear interpolation was performed using these four original elevation values. Within the structured grid cell G-0510, 400 interpolation points were uniformly selected at intervals of 0.5 meters by 0.5 meters for bilinear interpolation. The spatial average of the 400 interpolation results yielded an average ground elevation of 14.37 meters for the structured grid cell G-0510. Data shows that when using the general coupled mode of AU2020101587A4 for simulation, due to the lack of consideration for the constraint of the physical water flow area of ​​the storm drain grate and the dynamic feedback of surface water depth, the predicted maximum water accumulation depth was 0.62 meters, while the measured value in the area was 0.52 meters, resulting in a prediction error as high as 19.2%.

[0066] In contrast, the technical solution proposed in this application effectively solves the problems of mass non-conservation and neglect of surface water backflow effect commonly found in general coupled models by introducing the physical constraint that the virtual exchange orifice water flow area equals the actual water flow area of ​​the storm drain grate, and combining it with a time-series closed-loop coupled algorithm of overflow judgment—orifice calculation—2D solution—water depth feedback. Under the control of this algorithm, the maximum water depth predicted by the model in this application is 0.51m, which is very close to the measured value of 0.52m, with an error of only 1.9%. In addition, the test also found that the SWMM one-dimensional model running alone, due to neglecting surface runoff, had a predicted value of only 0.35m (error 32.7%); while the two-dimensional model running alone, due to neglecting the drainage capacity of the underground pipe network, had a predicted value as high as 0.68m (error 30.8%). In summary, the technical solution of this application improves the simulation accuracy by 17.3 percentage points compared with AU2020101587A4, significantly improving the reliability of urban flooding early warning. Data shows that when using the general coupled mode AU2020101587A4 for simulation, due to the lack of consideration for the constraints of the physical water flow area of ​​the storm drain grate and the dynamic feedback of the surface water depth, the predicted maximum water accumulation depth is 0.62m, while the actual measured value in the area is 0.52m, resulting in a prediction error as high as 19.2%.

[0067] In contrast, the technical solution proposed in this application, by introducing the physical constraint that "the water-passing area of ​​the virtual exchange orifice is equal to the actual water-passing area of ​​the storm drain grate," and combining it with a time-series closed-loop coupling algorithm of "overflow judgment—orifice calculation—2D solution—water depth feedback," effectively solves the problems of mass non-conservation and neglect of surface water backwater effect commonly found in general coupled models. Under the control of this algorithm, the maximum water depth predicted by the model in this application is 0.51m, which is extremely close to the measured value of 0.52m, with an error of only 1.9%. In addition, the test also found that the SWMM one-dimensional model running alone, due to neglecting surface runoff, had a predicted value of only 0.35m (error 32.7%); while the two-dimensional model running alone, due to neglecting the drainage capacity of the underground pipe network, had a predicted value as high as 0.68m (error 30.8%). In summary, the technical solution of this application improves the simulation accuracy by 17.3 percentage points compared with AU2020101587A4, significantly improving the reliability of urban flooding early warning. Specifically, if only conventional grid center mapping is used without configuring virtual exchange orifices with the same area as the physical operator, the two-dimensional model will exhibit severe mass non-conservation when calculating overflow diffusion. Furthermore, if only the orifice formula is used without incorporating back-feedback of water depth at the end of the time step, it is impossible to simulate the backwater effect caused by large-scale flooding on urban roads. This application achieves high-precision and high-stability reconstruction of complex urban flooding scenarios by closely integrating the grid terrain determined by bilinear interpolation, the physical area constraint of the virtual exchange orifice, the dynamic solution of the orifice flow formula, and the bidirectional feedback within the time step.

[0068] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. Based on SWMM A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, include: Receive geographic information data of pipeline networks and surface elevation data of the target urban area; A one-dimensional SWMM pipeline network model is configured based on the pipeline network geographic information data, and a two-dimensional hydrodynamic model is constructed by dividing the surface elevation data into structured grids. Establish a spatial mapping relationship between the pipe network nodes in the SWMM one-dimensional pipe network model and the structured grid cells in the two-dimensional hydrodynamic model, and configure coupling exchange interfaces and virtual exchange holes at the corresponding positions. The water flow area of ​​the virtual exchange hole and the actual water flow area of ​​the rain grate connected to the pipe network node satisfy a 1:1 mapping relationship. Within each simulation time step, bidirectional data interaction is performed through the coupled exchange interface: the overflow flow rate of the network nodes is calculated using the SWMM one-dimensional network model, and the overflow flow rate is calculated using the following formula:

2. Among them, The water flow area of ​​the virtual exchange hole. The difference between the current node head height of the pipeline network node and the current surface water depth of the target structured grid cell is used to update the surface water depth. This difference is then passed to the two-dimensional hydrodynamic model as the source term for the corresponding grid to update the surface water depth. Simultaneously, the updated surface water depth is fed back to the SWMM one-dimensional pipeline network model to update the accumulated water depth of the pipeline network node, thereby achieving bidirectional dynamic coupling between the underground pipeline network and the evolution of surface water accumulation.

3. The SWMM-based method according to claim 1 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, The steps for constructing a SWMM one-dimensional pipeline network model based on the pipeline network geographic information data specifically include: The spatial coordinates of each rainwater well, the bottom elevation of each inspection well, the front node number, the rear node number, the cross-sectional shape parameters, the roughness coefficient, and the maximum water conveyance capacity of each pipeline segment are extracted from the pipeline geographic information data. The spatial coordinates of each rainwater well are used as the node position in the SWMM model, and the bottom elevation of each inspection well is used as the bottom elevation of the corresponding node. The front-end node number and back-end node number of each pipe segment are mapped to the start node and end node in the SWMM model, respectively. The pipe cross-sectional shape parameters are converted into pipe cross-sectional geometric parameters in the SWMM model, and the pipe roughness coefficient is assigned the pipe Manning coefficient in the SWMM model. The maximum flow limit value for the corresponding pipeline in the SWMM model is set according to the maximum water conveyance capacity of the pipeline. All node and pipe parameters are organized according to the input file format of the SWMM model to generate a complete SWMM one-dimensional pipe network model.

4. The SWMM-based method according to claim 2 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, The steps for constructing a two-dimensional hydrodynamic model based on the surface elevation data specifically include: The surface elevation data is divided into regular structured grids according to a preset spatial resolution, and each structured grid cell corresponds to a calculation cell of a two-dimensional hydrodynamic model. Each structured grid cell is assigned an initial surface water depth and an initial surface roughness coefficient; A flux calculation section is set on each of the four boundaries of each structured grid cell to calculate the water exchange flux between two adjacent structured grid cells. The center point of the structured grid cell is used as the water level calculation point of the two-dimensional hydrodynamic model, and the vertex of the structured grid cell is used as the terrain elevation interpolation point of the two-dimensional hydrodynamic model. The average ground elevation of each structured grid cell is obtained by bilinear interpolation of the surface elevation data using the terrain elevation interpolation points. The average ground elevation, initial surface water depth, initial surface roughness coefficient, and flux calculation cross-sections between adjacent grid cells of all structured grid cells are combined into a complete two-dimensional hydrodynamic model.

5. The SWMM-based method according to claim 1 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, The step of setting a coupling exchange interface at the corresponding position of each pipe network node and surface grid cell between the SWMM one-dimensional pipe network model and the two-dimensional hydrodynamic model specifically includes: Based on the spatial coordinates of the pipeline node, locate the target structured grid cell where the node is located in the two-dimensional hydrodynamic model; A virtual exchange hole is configured at the geometric center of the target structured grid cell, and the water passage area of ​​the virtual exchange hole is configured to be the actual water passage area of ​​the rainwater grate connected to the pipe network node. The water flow area parameter remains constant during the simulation and has a 1:1 mapping relationship with the physical water flow capacity of the rain grate; A forward data transmission channel from the network node to the virtual switching port and a reverse data transmission channel from the virtual switching port to the network node are established to form the coupled switching interface.

6. The SWMM-based method according to claim 4 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, The overflow rate calculated by the SWMM one-dimensional pipe network model is transmitted to the two-dimensional hydrodynamic model in real time through the coupling exchange interface, and the surface water depth calculated by the two-dimensional hydrodynamic model is fed back to the SWMM one-dimensional pipe network model in real time, forming a two-way coupled SWMM. The steps of a two-dimensional hydrodynamic coupling model include: Read the current node head height of the pipeline node within the current time step; When the current node head height exceeds the sum of the node bottom elevation and the local head loss of the rainwater grate, the overflow flow rate of the pipeline node to the corresponding virtual exchange orifice is calculated based on the hydraulic orifice flow rate formula. The overflow flow rate is transmitted to the two-dimensional hydrodynamic model through the forward data transmission channel, and is added as a source term to the water balance equation of the target structured grid cell to solve and update the surface water depth of the grid cell. At the end of the time step, the updated surface water depth is fed back to the pipeline nodes through the reverse data transmission channel to correct the overflow flow calculation conditions in the next time step.

7. The SWMM-based method according to claim 5 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, The overflow flow rate is calculated using the orifice flow rate formula, where the head difference above the orifice is the difference between the current node's head height and the current surface water depth of the target structured grid cell.

8. The SWMM-based method according to claim 2 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, The pipe cross-sectional shape parameters are converted into pipe cross-sectional geometric parameters in the SWMM model, and the pipe roughness coefficient is assigned the pipe Manning coefficient in the SWMM model. Specifically, this includes: Determine the shape type indicated by the pipe cross-section shape parameters; When the shape type is circular, the pipe diameter is extracted from the pipe cross-section shape parameters, and the pipe diameter is directly mapped to the inner diameter of the circular pipe in the SWMM model to obtain the pipe cross-sectional geometric parameters. When the shape type is rectangular, the pipe width and pipe height are extracted from the pipe cross-section shape parameters, and the pipe width and pipe height are mapped to the width and height dimensions of the rectangular pipe in the SWMM model, respectively, so as to obtain the pipe cross-sectional geometric parameters. After completing the mapping of the geometric parameters of the pipe cross section, the pipe roughness coefficient of the corresponding pipe is read from the pipeline network geographic information data, and the value of the pipe roughness coefficient is directly assigned to the pipe Manning coefficient of the pipe in the SWMM model.

9. The SWMM-based method according to claim 3 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, A flux calculation section is set on each of the four boundaries of each structured grid cell to calculate the water exchange flux between two adjacent structured grid cells, specifically including: Obtain the geometric edges of structured mesh elements in a two-dimensional hydrodynamic model; On the geometric edges of the structured grid cells, each edge is divided into a predetermined number of flux calculation sections. Determine the pairs of parallel boundary lines between two adjacent structured mesh cells; Based on the corresponding flux calculation sections of the boundary line, calculate the surface water exchange flux passing through the center of each flux calculation section. The total water exchange flux between two adjacent structured grid cells is obtained by summarizing the water exchange flux across all flux calculation sections along the boundary line.

10. The SWMM-based method according to claim 3 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, The average ground elevation of each structured grid cell is obtained by bilinear interpolation of the surface elevation data using the terrain elevation interpolation points, specifically including: Identify the terrain elevation interpolation points corresponding to the four vertices of the structured grid cell; Extract the original elevation values ​​of these four terrain elevation interpolation points from the surface elevation data; Within the planar range of the structured grid cell, bilinear interpolation calculations are performed using the original elevation values ​​of the four terrain elevation interpolation points; Spatial averaging is performed on multiple interpolation results obtained by bilinear interpolation within the structured grid cell; The calculated spatial average value is used as the average ground elevation of the structured grid cell.

11. The SWMM-based method according to claim 4 A two-dimensional hydrodynamic coupling model for simulating urban flooding is characterized by, Creating a virtual exchange hole at the geometric center of the target structured mesh cell, specifically including: Calculate the planar coordinates of the geometric center point of the target structured mesh cell; Locate the position of the geometric center point in the grid data of the two-dimensional hydrodynamic model; A virtual exchange hole geometry representing the physical exchange process is generated at the location; Read the actual size information of the rainwater grate connected to the pipeline node from the pipeline geographic information data; Calculate the actual water passage area of ​​the rain grate based on the actual size information; The water flow area parameter value of the virtual exchange hole geometry in the two-dimensional hydrodynamic model is set to the calculated actual water flow area to complete the creation of the virtual exchange hole.

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