A breach position adaptive plain reservoir dam-break simulation method

Abstract

The present application belongs to the technical field of hydraulic engineering, and discloses a plain reservoir dam-break simulation method with adaptive breach location, aiming to solve the problems of low modeling efficiency, large human error and poor model reusability of the traditional dam-break simulation method when the breach location of the plain reservoir is uncertain. Through the "predefined adaptive boundary + automatic matching" mechanism, the present application decouples the breach location and the grid division, shortens the single scene switching to the minute level, eliminates human operation errors, supports the dam-break simulation at any location, greatly improves the efficiency, reliability and flexibility of the plain reservoir dam-break risk analysis, and provides strong technical support for flood control and disaster reduction emergency decision-making.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, specifically the direction of numerical simulation of dam-break floods in plain reservoirs and flood control and disaster reduction technology, and particularly relates to a method for simulating dam-break floods in plain reservoirs with adaptive breach location. Background Technology

[0002] Dam break floods are a highly destructive type of natural disaster in the field of water conservancy engineering. Their floods are characterized by high peak flow, rapid evolution, and wide impact. Once they occur, they often cause devastating damage to downstream towns, farmland, and ecosystems. Therefore, accurate and efficient numerical simulation of dam break floods is the core technical support for flood control and disaster reduction decision-making, risk assessment, and emergency plan formulation.

[0003] There is a significant “scenario adaptation bias” in the current research and application of dam break simulation technology at home and abroad: most of the existing mature solutions are designed for mountain reservoirs. Due to terrain constraints, such reservoirs usually have clear main dam / secondary dam sites, and the breach locations are highly concentrated in specific dam sections. Therefore, traditional simulation methods generally adopt the technical approach of “pre-setting fixed breach locations” – that is, directly locking the spatial coordinates and attribute parameters of the breach boundary during the mesh generation stage, and then only needing to carry out flood evolution calculations based on fixed boundary conditions. The technical logic is highly matched with the breach characteristics of mountain reservoirs, and can achieve good simulation results in mountain scenarios.

[0004] However, the structural characteristics of reservoirs in plains differ fundamentally from those in mountainous areas, rendering traditional technical approaches completely inapplicable. Plains reservoirs typically employ a "dam-encircling" construction model, with dams continuously distributed around the reservoir perimeter for lengths ranging from several kilometers to tens of kilometers. The risk of dam failure is not concentrated in specific dam sections but can occur randomly at any location within the dam due to factors such as uneven dam mass, localized seepage damage, and extreme hydrological loads (e.g., heavy rainfall, sustained high water levels). This inherent characteristic exposes three core technical flaws in traditional methods for plains reservoir scenarios, and existing technologies have yet to offer effective solutions:

[0005] 1. The modeling efficiency is extremely low and cannot meet emergency needs. To simulate flood processes at different breach locations, traditional methods require re-meshing for each potential breach. Because the boundary properties of traditional meshes are strongly tied to the breach location, changing the breach location means readjusting the mesh topology to fit the new breach boundary. Furthermore, the modeling scope of plain reservoirs is vast and the terrain data is complex; a single mesh generation can take hours to days. When assessing the risk of multiple potential breaches, the workload linearly accumulates, completely failing to meet the decision-making needs of "hourly" emergency simulations during sudden dam breaches.

[0006] 2. Boundary setting is cumbersome and prone to human error. Each time the breach location is changed, not only is it necessary to re-mesh, but also to manually redefine the flow boundary sequence of the breach boundary and its connection with the surrounding solid wall boundaries. Manual operation is not only time-consuming, but also prone to errors due to differences in human operation (such as boundary coordinate positioning deviations and chaotic flow boundary sequences), resulting in inconsistent simulation results for different breach scenarios and affecting the reliability of risk assessment.

[0007] While some existing technologies have attempted to optimize the simulation process for dam breaks in plain reservoirs (e.g., simplifying mesh parameters and pre-setting partial boundary templates), none have overcome the core limitation of "strong binding between the breach location and the mesh boundary." Either they can only simulate a few preset points on the dam, failing to cover arbitrary breach locations; or while they support boundary attribute modification, they still rely on local mesh adjustments, failing to achieve true "adaptation." Therefore, there is an urgent need for a plain reservoir dam break simulation technology that can completely break free from the binding relationship between mesh generation and breach location, enabling rapid adaptation to any breach location, thus addressing the pain points of low efficiency, large errors, and poor reusability of traditional methods. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies that require repeated modeling for different breach locations, and to achieve rapid setting and adaptive simulation of arbitrary breach locations, this invention proposes a method for simulating dam failures in plain reservoirs with adaptive breach locations. This method can flexibly address the uncertainty of breach locations in plain reservoirs, significantly improving the efficiency and flexibility of dam failure risk analysis, and providing stronger technical support for emergency management and disaster prevention and mitigation efforts.

[0009] The objective of this invention is achieved as follows:

[0010] This invention provides a method for simulating dam failure in plain reservoirs with adaptive breach location, comprising the following steps:

[0011] Step 1: Based on the surface elevation around the plain reservoir to be studied, preliminarily determine the potential inundation range after the dam breach and determine the scope of the hydrodynamic model construction; at the same time, obtain the vector boundary data of the plain reservoir along the dam body, the digital terrain model of the area excluding the reservoir within the scope of the hydrodynamic model construction, land use type information, and the water level-discharge relationship of each river outlet section within the scope of the hydrodynamic model construction.

[0012] Step 2: Using the hydrodynamic model construction area determined in Step 1 as the outer boundary and the plain reservoir vector boundary as the inner boundary, the modeling area is meshed using a triangular unstructured mesh. The reservoir area inside the inner boundary is treated as a cavity and does not participate in the meshing. The digital terrain model obtained in Step 1 is used to perform elevation interpolation on the meshed area, and the land use type information is used to assign roughness values ​​to the meshed area to obtain the elevation and roughness of each mesh node. Based on this, the elevation and roughness of the mesh center are calculated and used as the calculation parameters of the mesh.

[0013] Step 3: Add a BC field describing boundary properties to all grid edges, with a default value of "0"; define the grid edge containing the outer boundary as a solid wall boundary and modify its BC field value to "1"; based on the river distribution within the modeling range, define the grid edge containing each river outlet section as the downstream outflow boundary and modify its BC field value to "2"; define the grid edge containing the inner boundary as an adaptive variable boundary and modify its BC field value to "9".

[0014] Step 4: According to the index order of the grid edges, traverse all grid edges with a BC field value of "9", calculate the coordinates of the center point of each grid edge based on the coordinates of the two endpoints of each grid edge, and establish and store an array structure containing the correspondence between "grid edge index number - center point x-coordinate - center point y-coordinate".

[0015] Step 5: Before starting the breach calculation scheme, obtain the breach parameters, breach location information, and model calculation parameters;

[0016] Step 6: Based on the breach location information obtained in Step 5, match the adaptive variable boundary closest to the breach center in the correspondence array established in Step 4, modify the grid edge type corresponding to this boundary to dam break flow boundary, and adjust its BC field value from "9" to "4"; at the same time, modify the BC field value of the remaining unmatched adaptive variable boundaries to "1".

[0017] Step 7: Calculate the dam-break flood flow process based on the breach parameters obtained in Step 5, and use this flow process as the boundary condition of the dam-break flow boundary in Step 6; based on the name of the river outlet section, match the water level-discharge relationship obtained in Step 1 with the downstream outflow boundary defined in Step 3, and use the matched water level-discharge relationship as the control condition of the corresponding downstream outflow boundary.

[0018] Step 8: Based on the model calculation parameters obtained in Step 5, perform flood analysis calculations using the two-dimensional hydrodynamic model and output the model calculation results;

[0019] Step 9: After completing the single breach calculation schemes in Steps 5 to 8, if it is necessary to modify the breach parameters or breach location information, repeat Steps 5 to 8 to achieve the model's breach location adaptive function; if no modification is needed, terminate the task and complete the plain reservoir dam breach simulation.

[0020] This invention addresses the core challenge of the uncertainty in the location of breaches in plain reservoirs by achieving a technological breakthrough through a combination of "predefined adaptive boundaries and an automatic matching mechanism," with the following beneficial effects:

[0021] 1. Significantly improves simulation efficiency and adapts to emergency needs. This invention completely decouples breach location adjustment from mesh generation. When changing a breach, there is no need to re-mesh; only the coordinates of the new breach center need to be input, and the program can automatically match the corresponding adaptive boundary and modify the attributes. The time for a single scene switch is shortened from the traditional "hours to days" to "minutes," enabling rapid simulation of multiple potential breach locations and providing support for emergency decision-making in dam-break floods.

[0022] 2. Eliminate human error and improve the reliability of results. By automatically calculating the coordinates of the adaptive boundary center point, automatically matching the breach boundary and assigning boundary conditions, the program replaces traditional manual operation, fundamentally avoiding errors introduced by human operation deviations, ensuring uniformity in simulation standards for different breach scenarios, and significantly improving the consistency and reliability of results.

[0023] 3. Enhance simulation flexibility and cover all scenarios: Supports simulation of breaches at any location of the dam. Inputting the target coordinates will automatically match the boundary, breaking through the traditional limitation of only simulating preset points. Through the loop mechanism, multiple breach schemes can be quickly set up and simulated, providing a flexible tool for the full-scenario and multi-dimensional assessment of dam breach risks in plain reservoirs. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Figure 1 This is a flowchart illustrating the plain reservoir dam failure simulation method with adaptive breach location as described in this invention.

[0026] Figure 2 This is a schematic diagram of the boundary types defined in the embodiments of the present invention;

[0027] Figure 3 This is a schematic diagram illustrating the adaptive rupture boundary in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed herein will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] Example 1:

[0030] like Figure 1 As shown in the figure, this embodiment provides a method for simulating dam failure in plain reservoirs with adaptive breach location, including the following steps:

[0031] Step 1: Based on the surface elevation around the plain reservoir to be studied, use historical flood trace analysis, contour line analysis, or simplified hydraulic methods to preliminarily determine the potential inundation range after dam failure and determine the scope of hydrodynamic model construction.

[0032] Simultaneously, the vector boundary data of the plain reservoir along the dam body, the digital terrain model of the area excluding the reservoir within the scope of the hydrodynamic model construction, land use type information, and the water level-discharge relationship of each river outlet section within the scope of the hydrodynamic model construction are obtained.

[0033] Specifically, the defined hydrodynamic model construction area should be converted into vector boundary data for use as the control boundary for mesh generation; the vector boundary data of the hydrodynamic model construction area and the reservoir area should be closed polygons with clear and distinct boundaries; the digital terrain model should be raster data with a resolution of not less than 10m and an accuracy of not less than 1cm; and land use type information should be used to extract roughness information within the modeling area.

[0034] Step 2: Using the hydrodynamic model construction area determined in Step 1 as the outer boundary (the area outside the outer boundary does not participate in mesh generation), and the plain reservoir vector boundary as the inner boundary, the modeling area is meshed using a triangular unstructured mesh with a side length not exceeding 10m (which can automatically fit the inner and outer boundaries). The reservoir area inside the inner boundary is treated as a cavity and does not participate in mesh generation. The digital terrain model obtained in Step 1 is used to perform elevation interpolation on the meshed area, and the land use type information is used to assign roughness values ​​to the meshed area to obtain the elevation and roughness of each mesh node. Based on this, the elevation and roughness of the mesh center are calculated and used as the calculation parameters for that mesh.

[0035] The elevation and roughness of the grid center are calculated using the following interpolation formula:

[0036]

[0037] In the formula, Z P The value of attribute P, i.e., elevation or roughness, is to be determined for the center of the grid; Z A Z B Z C S represents the attribute values ​​of three nodes A, B, and C in the grid. PBC ,S PAC ,S PAB ,S ABC Let be the area of ​​the triangle formed by the subscript nodes.

[0038] Step 3: According to the index order of the mesh edges, add a BC field to all mesh edges to describe the boundary attributes, and set the default value to "0"; define the mesh edge where the outer boundary is located as a solid wall boundary, and modify its BC field value to "1".

[0039] Assuming a river exists within the study area of ​​this embodiment, the grid edge containing the river outlet section is defined as the downstream outflow boundary, and its BC field value is modified to "2"; the grid edge containing the inner boundary is defined as the adaptive variable boundary, and its BC field value is modified to "9". The grid boundary type is defined as follows. Figure 2 As shown.

[0040] Step 4: Following the index order of the grid edges, traverse all grid edges with a BC field value of "9". Calculate the coordinates of the center point of each grid edge based on the coordinates of its two endpoints. Create and store an array structure containing the correspondence between the grid edge index number, the x-coordinate of the center point, and the y-coordinate of the center point.

[0041] Step 5: Before starting the breach calculation scheme, obtain the breach parameters, breach location information, and model calculation parameters. The breach parameters include the initial breach bottom height, initial reservoir water level, initial breach width, final breach bottom height, maximum breach width, and breach development history; the breach location information is the horizontal and vertical coordinates of the breach center; the model calculation parameters include the calculation start and end dates, calculation step size, and output step size.

[0042] Step 6: Based on the breach location information obtained in Step 5, match the adaptive variable boundary closest to the breach center in the correspondence array established in Step 4, change the grid edge type corresponding to the boundary to the dam break flow boundary, and adjust its BC field value from "9" to "4"; at the same time, change the BC field value of the remaining unmatched adaptive variable boundaries to "1".

[0043] Specifically, in this embodiment, assuming the breach center is located at (x0, y0), there are three adaptive variable boundaries with grid indices a, b, and c. The center point coordinates of the three grid edges are (x1, y1), (x2, y2), and (x3, y3), respectively. Then, the index number i of the adaptive variable boundary grid edge closest to the breach center can be calculated using the following formula:

[0044]

[0045] Assuming the value of i obtained from the above formula is c, then in this embodiment, the adaptive variable boundary closest to the breach is the grid edge with index c. This grid edge is defined as a dam-break flow boundary, and its "BC" attribute value is changed from "9" to "4". Simultaneously, the "BC" attribute value of the unmatched adaptive variable boundaries, i.e., the grid edges with indices a and b, is changed to "1". The boundary attributes after the breach boundary adaptation are as follows: Figure 3 As shown.

[0046] Step 7: Calculate the dam-break flood flow process based on the breach parameters obtained in Step 5, and use this flow process as the boundary condition for the dam-break flow boundary in Step 6; based on the name of the river outlet section, match the water level-discharge relationship obtained in Step 1 with the downstream outflow boundary defined in Step 3, and use the matched water level-discharge relationship as the control condition for the corresponding downstream outflow boundary.

[0047] Step 8: Based on the model calculation parameters obtained in Step 5, use the two-dimensional shallow water equation set as the governing equations and solve it using the finite volume method. Perform flood analysis calculations on the two-dimensional hydrodynamic model and output the model calculation results, including the flood velocity and water depth information of each unit at each time point in the model, to complete this breach calculation scheme.

[0048] The two-dimensional shallow water equations are shown below:

[0049]

[0050] In the formula: h is the water depth in meters (m); u and v are the flow velocities in the x and y directions, respectively, in meters per second (m / s); t is the current time step in seconds (s); B(x,y) is the bottom slope elevation in meters (m); τ is the friction term; the subscripts bx and by are the frictional components in the x and y directions, respectively; and g is the acceleration due to gravity in meters per second (m / s²). 2 .

[0051] Step 9: After completing the single breach calculation schemes in Steps 5 to 8, if it is necessary to modify the breach parameters or breach location information, repeat Steps 5 to 8 to achieve the model's breach location adaptive function; if no modification is needed, terminate the task and complete the plain reservoir dam breach simulation.

[0052] Following the method described in this embodiment, a dam failure simulation of a plain reservoir was performed, and the simulation log is as follows:

[0053] INFO: - The remaining 1249 inner boundary types have been changed from BC=9 (adaptive) to BC=1 (solid).

[0054] INFO: Boundary conditions updated.

[0055] INFO: Loading breach parameters: Initial width = 20m, development time = 1.5h...

[0056] INFO: Initiating two-dimensional hydrodynamic calculations... ...

[0058] INFO: Calculation of Scheme 1 completed. Total time: 15.2 minutes. Results have been output.

[0059] INFO:---------------------------------

[0060] INFO:<<<<<<<Initiation Plan 2: Southwest Breach Simulation (No Remodeling Required)>>>>>>>

[0061] INFO: Received user input of the breach center coordinates: (X = 450125.8, Y = 3454321.6)

[0062] INFO: [Core Steps] The system resets the internal boundary conditions to BC=9.

[0063] INFO: [Core Steps] Begin automatically matching the nearest boundary among 1250 adaptive boundaries (BC=9)...

[0064] INFO: [Core Steps] Match successful! Nearest grid edge index: 245. Distance: 4.1 meters.

[0065] INFO: [Core Steps] Updating boundary conditions...

[0066] INFO: The boundary type of the grid edge

[245] has been changed from BC=9 (adaptive) to BC=4 (dam break flow).

[0067] INFO: - The remaining 1249 inner boundary types have been changed from BC=9 (adaptive) to BC=1 (solid).

[0068] INFO: Boundary conditions updated. Scene transition time: 1.2 seconds.

[0069] INFO: Loading breach parameters: Initial width = 30m, development time = 1.0h...

[0070] INFO: Initiating two-dimensional hydrodynamic calculations... ...

[0072] INFO: Calculation for Scheme 2 is complete. Total time: 15.1 minutes. Results have been output.

[0073] INFO: <<<<<<<All simulation tasks completed>>>>>>>

[0074] The above simulation logs clearly demonstrate the beneficial effects of the method described in this invention:

[0075] (1) High model reuse avoids redundant work: The log shows that the basic model plain_reservoir_model.dat is only loaded once at the start of the program. When switching from "Solution 1" to "Solution 2", the log clearly states "(No need to remodel)". This is in stark contrast to the traditional method, which requires several hours of re-meshing and setting up every time the breach location is changed, greatly reducing manpower and time costs.

[0076] (2) Adaptive breach location and extremely rapid response: For two completely different breach locations (northeast corner and southwest side), the method of this invention only requires the user to input the target center coordinates. The "[core step]" within the system—automatic matching and updating of boundary conditions—can be completed within 1-2 seconds. This reduces the switching time of a single scene from "hours" in traditional methods to "seconds," fully meeting the "minutes" response requirements for emergency decision-making.

[0077] (3) Automated process to eliminate human error: The entire process of specifying the location of the breach (matching the nearest boundary and modifying the boundary type) is completed automatically by the program, avoiding the positioning deviation or assignment error that may be introduced by manual boundary positioning and manual assignment in traditional methods, and ensuring the consistency and reliability of the results of different simulation schemes.

[0078] Finally, it should be noted that the above is only used to illustrate the technical solutions of the present invention and not 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 solutions of the present invention (such as the application of various formulas, the order of steps, etc.) without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for simulating dam failure in plain reservoirs with adaptive breach location, characterized in that, The method includes the following steps: Step 1: Based on the surface elevation around the plain reservoir to be studied, preliminarily determine the potential inundation range after the dam breach and determine the scope of the hydrodynamic model construction; at the same time, obtain the vector boundary data of the plain reservoir along the dam body, the digital terrain model of the area excluding the reservoir within the scope of the hydrodynamic model construction, land use type information, and the water level-discharge relationship of each river outlet section within the scope of the hydrodynamic model construction. Step 2: Using the hydrodynamic model construction area determined in Step 1 as the outer boundary and the plain reservoir vector boundary as the inner boundary, the modeling area is meshed using a triangular unstructured mesh. The reservoir area inside the inner boundary is treated as a cavity and does not participate in the meshing. The digital terrain model obtained in Step 1 is used to perform elevation interpolation on the meshed area, and the land use type information is used to assign roughness values ​​to the meshed area to obtain the elevation and roughness of each mesh node. Based on this, the elevation and roughness of the mesh center are calculated and used as the calculation parameters of the mesh. Step 3: Add a BC field describing boundary properties to all grid edges, with a default value of "0"; define the grid edge containing the outer boundary as a solid wall boundary and change its BC field value to "1"; based on the river distribution within the modeling range, define the grid edge containing each river outlet section as the downstream outflow boundary and change its BC field value to "2"; define the grid edge containing the inner boundary as an adaptive variable boundary and change its BC field value to "9". Step 4: According to the index order of the grid edges, traverse all grid edges with a BC field value of "9", calculate the coordinates of the center point of each grid edge based on the coordinates of the two endpoints of each grid edge, and establish and store an array structure containing the correspondence between "grid edge index number - center point x-coordinate - center point y-coordinate". Step 5: Before starting the breach calculation scheme, obtain the breach parameters, breach location information, and model calculation parameters; Step 6: Based on the breach location information obtained in Step 5, match the adaptive variable boundary closest to the breach center in the correspondence array established in Step 4, change the grid edge type corresponding to this boundary to dam break flow boundary, and adjust its BC field value from "9" to "4"; at the same time, change the BC field value of the remaining unmatched adaptive variable boundaries to "1". Step 7: Calculate the dam-break flood flow process based on the breach parameters obtained in Step 5, and use this flow process as the boundary condition of the dam-break flow boundary in Step 6; based on the name of the river outlet section, match the water level-discharge relationship obtained in Step 1 with the downstream outflow boundary defined in Step 3, and use the matched water level-discharge relationship as the control condition of the corresponding downstream outflow boundary. Step 8: Based on the model calculation parameters obtained in Step 5, perform flood analysis calculations using the two-dimensional hydrodynamic model and output the model calculation results; Step 9: After completing the single breach calculation schemes in Steps 5 to 8, if it is necessary to modify the breach parameters or breach location information, repeat Steps 5 to 8 to achieve the model's breach location adaptive function; if no modification is needed, terminate the task and complete the plain reservoir dam breach simulation.

2. The method for simulating dam failure in plain reservoirs with adaptive breach location according to claim 1, characterized in that, In step one, the potential inundation range after the dam breach is preliminarily determined using historical flood trace analysis, contour line analysis, or simplified hydraulic methods.

3. The method for simulating dam failure in plain reservoirs with adaptive breach location according to claim 1, characterized in that, In step two, the elevation and roughness of the grid center are calculated using the following interpolation formula: In the formula, Z P The value of attribute P, i.e., elevation or roughness, is to be determined for the center of the grid; Z A Z B Z C S represents the attribute values ​​of three nodes A, B, and C in the grid. PBC ,S PAC ,S PAB ,S ABC Let be the area of ​​the triangle formed by the subscript nodes.

4. The method for simulating dam failure in plain reservoirs with adaptive breach location according to claim 1, characterized in that, In step five, the breach parameters include the initial breach bottom height, initial reservoir water level, initial breach width, final breach bottom height, maximum breach width, and breach development history; the breach location information is the horizontal and vertical coordinate values ​​of the breach center; the model calculation parameters include the calculation start and end dates, calculation step size, and output step size.

5. The method for simulating dam failure in plain reservoirs with adaptive breach location according to claim 1, characterized in that, In step eight, the governing equations of the two-dimensional hydrodynamic model are a set of two-dimensional shallow water equations, which are solved using the finite volume method or the finite difference method.

6. The method for simulating dam failure in plain reservoirs with adaptive breach location according to claim 1, characterized in that, In step eight, the two-dimensional shallow water equations are as follows: In the formula: h is the water depth; u and v are the flow velocities in the x and y directions, respectively; t is the current time step; B(x,y) is the bottom slope elevation; τ is the friction term; the subscripts bx and by are the friction force components in the x and y directions, respectively; and g is the gravitational acceleration.

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