A rigid dam flood evolution analysis method

Abstract

This invention relates to the field of dam-break flood evolution technology, addressing the problems of low convergence rate and low computational efficiency in coupled simulations caused by the lack of adaptive synchronization mechanisms in existing models. Specifically, it relates to a method for analyzing the evolution of rigid dam-break floods. The method involves acquiring and preprocessing multi-source datasets of the rigid dam to obtain a standard dataset, and then sequentially performing inflow flood process calculations and flood regulation calculations to obtain the dam-break flood process at the dam site. Based on downstream topographic data, a one-dimensional river channel model is constructed to characterize flood propagation along the river, and a two-dimensional computational domain model is constructed to characterize the planar flood diffusion in the floodplain. This invention dynamically matches the computational step size of the one-dimensional river channel model and the two-dimensional floodplain model through adaptive time step adaptation, improving the convergence rate and stability of the coupled simulation. It effectively avoids the problems of numerical oscillation or divergence and excessive computation time caused by traditional fixed step sizes, thus improving computational efficiency.

Description

Technical Field

[0001] This invention relates to the field of dam-break flood evolution technology, and in particular to a method for analyzing the evolution of rigid dam-break floods. Background Technology

[0002] Rigid dams, as core flood control structures in water conservancy projects, have a low probability of failure, but once they do occur, they can trigger sudden and destructive flood disasters, directly threatening the safety of the downstream riverbank environment. Simulation of rigid dam failure flood evolution is a key technical support for basin flood control planning and emergency response plan development. Currently, to balance the efficiency of river propagation along the channel with the accuracy of floodplain planar diffusion, one- or two-dimensional coupled models are mainly used to simulate dam failure flood evolution.

[0003] Traditional one-dimensional coupled models often employ a coupling mode that links a one-dimensional river channel model with a two-dimensional flood zone model. This makes it difficult to establish an effective lateral coupling mechanism and lacks a synchronization and coordination mechanism. Consequently, the one-dimensional coupled models suffer from poor spatial boundary matching, asynchronous time steps, and the absence of a lateral water exchange mechanism, which reduces the convergence rate and computational efficiency of the coupled simulation. This results in insufficient accuracy and practicality in dam-break flood evolution simulation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for analyzing the evolution of rigid dam break floods. This method solves the technical problem of low convergence rate and low computational efficiency in coupled simulations caused by the lack of an adaptive synchronization mechanism between the one-dimensional channel model and the two-dimensional flood zone model. It achieves the goal of adaptive synchronization of the time steps between the one-dimensional channel model and the two-dimensional flood zone model, thereby improving the convergence rate and computational efficiency of coupled simulations.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for analyzing the evolution of rigid dam break floods, the method comprising the following steps: S1. Obtain and preprocess the multi-source dataset of the rigid dam to obtain the standard dataset, and sequentially complete the inflow flood process calculation and flood regulation calculation to obtain the dam break flood process at the dam site; S2. Based on downstream topographic data, construct a one-dimensional river channel model to characterize the propagation of floods along the river and a two-dimensional computational domain model to characterize the diffusion of floodplain planar floods. Through the coupling interface, realize the spatial boundary matching, time step synchronization and flow and water level data interaction between the one-dimensional model and the two-dimensional model to obtain a one-dimensional and two-dimensional coupled model. S3. Using the dam break flood process at the dam site as the boundary condition, the dynamic evolution simulation of the dam break flood flow at the dam site is carried out based on a one-dimensional coupled model to obtain the flow and water level of the downstream river channel at the preset cross section, as well as the flood inundation elements in the two-dimensional computational domain. The flood inundation elements include the inundation range, water depth, and approach velocity. S4. Based on the flow rate and water level of the downstream river channel at the preset cross-section and the flood inundation factors, calculate the peak arrival time, maximum average flow velocity, and maximum inundation depth of the downstream preset cross-section, and generate the comprehensive analysis results of the dam-break flood.

[0006] Furthermore, the standard dataset includes dam structure data, watershed hydrological data, and downstream topographic data; The dam structure data includes dam type, total dam length, spillway crest width, spillway crest elevation, and breach sub-data; and the breach sub-data includes at least the breach flow coefficient and breach width. The watershed hydrological data includes average rainfall, catchment area, steady infiltration rate, initial loss, and channel roughness coefficient. The downstream topographic data includes river channel cross-section data, river channel cross-section elevation, riverbed elevation, and floodplain boundary data.

[0007] Furthermore, the specific steps include the following: S11. Based on the watershed hydrological data in the standard dataset, calculate the net rainfall depth and inflow flood discharge in the watershed for any given time period. This represents the time-varying process of the flood discharge flowing into the reservoir, providing the upstream input boundary for flood control calculations to obtain the inflow flood process. The calculation formula is as follows: In the above formula, Indicates the first Net rainfall depth in the basin during the period Indicates the first The average rainfall over a given period, specifically the rainfall measured at rain gauge stations within the basin during that period. This represents the initial watershed loss, specifically the amount of rainfall used in the early stages of precipitation to meet the needs of vegetation interception and initial soil infiltration. This represents the steady-state infiltration rate of a watershed, specifically the stable rate of rainwater infiltration after the watershed soil reaches saturation. Indicates the length of the calculation period. Indicates the first Inflow of floodwater during a given period This refers to the catchment area of ​​a watershed, specifically the catchment area of ​​the reservoir where the rigid dam is located. Indicates the first The net rainfall depth in the basin during each rainfall period Represents the ordinate of the unit hydrograph in the watershed, specifically characterizing the first... Net rainfall per unit time period in the first The proportion of convergence response formed during the time period This indicates a unit conversion factor used to unify the dimensions of rainfall, area, and flow rate. S12, according to the first Using inflow flood discharge and dam structure data for a given period, and employing the reservoir water balance equation and flood discharge formula, the total inflow, total outflow, and outflow flood discharge for any given period are calculated to complete the flood control calculation. The calculation formulas are as follows: In the above formula, Indicates the first Total water inflow during the period Indicates the first Total water outflow during the period Indicates the initial water storage of the reservoir during the period, the first... The water level in the reservoir at the end of the period. This indicates the reservoir's water storage at the end of the time period, the first... The water level in the reservoir at the end of the period. Indicates the first Outflow of floodwater during a given period This represents the spillway flow coefficient, a coefficient reflecting the spillway's discharge efficiency, with a value ranging from 0.35 to 0.55. This indicates the width of the spillway crest, specifically the effective width of the spillway's discharge cross-section. Represents gravitational acceleration. Indicates the first Water level in front of the dam during the specified time period This indicates the elevation of the spillway crest, specifically the altitude of the spillway crest. S13, the first result obtained from flood control calculation Using the water level and dam structure data for a given period, the dam-break flood discharge at the dam site is calculated. This represents the time-varying process of the dam-break flood discharge at the dam site, providing the upstream input boundary for the subsequent one-dimensional coupled model. The calculation formula is as follows: In the above formula, Indicates the first The dam-break flood discharge at the dam site during a given period is a quantitative indicator of the dam-break flood process at the dam site. This represents the breach flow coefficient, a coefficient used to reflect the breach discharge efficiency (determined based on dam material and breach shape data from a standard dataset, with a value range of 0.5 to 0.7). Indicates the first The breach width during a given time period is defined as follows: for a rigid dam, the breach is assumed to be instantaneous and complete; during the dam failure process, the breach width is the total length of the dam's overflow section. This indicates the elevation of the bottom of the weir.

[0008] Furthermore, the specific steps include the following: S21. Using the river centerline as the axis, a one-dimensional grid is generated by equidistant segmentation and topographic abrupt change point densification strategy to obtain the spacing between each grid node. The cross-sectional area and hydraulic radius of the river channel in the downstream topographic data are extracted. The dam break flood flow at the dam site is taken as the upstream input boundary. Based on the Saint-Venant equations and the propagation characteristics along the route, the one-dimensional hydrodynamic control equations are obtained by discretizing and solving using the finite volume method. S22. Extract the boundary data of the flood region, extend it outward by a preset threshold (the preset threshold can be set to 5%) as a buffer zone (to avoid boundary effects) to form a two-dimensional computational domain, and generate an unstructured triangular mesh. Ensure that the minimum interior angle of the triangular mesh is ≥30°, the maximum interior angle is ≤120°, and the mesh distortion rate is ≤15% to obtain the mesh cell size. Based on the shallow water equations and planar diffusion characteristics, use the finite volume method to discretize and solve the two-dimensional hydrodynamic control equations. S23. Extract feature points of the one-dimensional river boundary and topographic feature points of the two-dimensional flood zone. The feature point density is positively correlated with the grid cell size. S24. Using the feature points of the one-dimensional river channel boundary as a reference, extend the two-dimensional flood area to generate a coupled overlapping area, and perform coordinate mapping between the feature points of the one-dimensional river channel boundary and the grid nodes of the two-dimensional coupled overlapping area. S25. Based on the grid node spacing of the one-dimensional model and the grid cell size of the two-dimensional model, obtain the stable time step of the one-dimensional model and the two-dimensional model to generate a unified time step of the coupled model, realize the dynamic adaptation of the one-dimensional river channel model and the two-dimensional computational domain model, and generate a one-dimensional coupled model.

[0009] Furthermore, the expression for the one-dimensional hydrodynamic governing equation is as follows: In the above formula, This represents the cross-sectional area of ​​the river channel, specifically the cross-sectional area occupied by the water flow at any section of the river channel, obtained from the river channel cross-sectional elevation in the downstream topographic data. This represents the cross-sectional flow rate of a river channel, specifically the volume of water passing through any cross-section of the channel per unit time. It is obtained by taking the dam-break flood discharge at the dam site as the upstream input boundary, and combining it with downstream topographic data, through the Saint-Venant equations. It is the result of flood propagation and energy dissipation along the river's course. This represents the lateral flow rate per unit width, specifically the rate of lateral water exchange per unit length of river channel. It represents the momentum flux per unit mass of water flow, characterizing the momentum transfer characteristics of water flow at a cross section. Indicates the water level at the river cross-section. Represents gravitational acceleration. This refers to the slope of the riverbed, specifically the gradient of the riverbed along its axial direction. The roughness coefficient represents the resistance characteristics of the riverbed / banks to water flow; it is derived from watershed hydrological data. The hydraulic radius is the ratio of the cross-sectional area of ​​the water flow to the wetted perimeter, which is the circumference of the water flow in contact with the river channel wall. It is calculated from the cross-section of the river channel based on downstream topographic data.

[0010] Furthermore, the expression for the two-dimensional hydrodynamic governing equations is as follows: In the above formula, This represents water depth, the vertical distance from the floodwater surface to the bed surface at any given location; it is the difference between the water level (the elevation of the floodwater surface at that location) and the bed elevation (the elevation of the natural bottom surface at that location). Indicates time, Indicates water flow at Flow velocity component in the direction, Indicates the bed surface is The slope in the direction is calculated from the riverbed elevation in the downstream topographic data of the standard dataset. Indicates the friction slope at Components in direction, Indicates water flow at Flow rate per unit width in the direction; in, , Indicates the elevation of the riverbed; , , This represents the roughness coefficient of the river channel.

[0011] Furthermore, step S3 specifically includes the following steps: S31. Extract the flood flow sequence at the dam site and perform linear interpolation to make its time step consistent with the unified time step of the one-dimensional coupled model, so as to obtain the boundary flow sequence adapted to the one-dimensional coupled model, ensuring the temporal accuracy of the boundary conditions. Set the boundary flow sequence as the upstream input boundary of the one-dimensional river channel model and synchronize it to the near-dam boundary of the two-dimensional computational domain model through the coupling interface. S32. Solve the Saint-Venant equations based on the boundary flow sequence and a one-dimensional channel model to obtain the water level and flow at each node of the one-dimensional channel at any given time. The one-dimensional channel model is discretized longitudinally, with the downstream channel along its axis (longitudinal coordinate). The node is divided into several discrete nodes, labeled as follows: The vertical coordinates of the nodes are In the Water levels at each node of the one-dimensional river channel at the next time step and traffic , respectively representing the first dimension of the river channel The flood water level at each node and the passage of the one-dimensional river channel per unit time. The flood discharge at each node corresponds to a cross-section. Based on the lateral flux feedback from the coupling interface and combined with the two-dimensional computational domain model, the corrected shallow water equations are solved to obtain the water depth and velocity of each grid in the two-dimensional flood zone at any given time. The two-dimensional flood zone model adopts a planar discretization method, dividing the downstream flood zone into several triangular computational grids, denoted as the first... The grid numbers are In the Water depth of each grid in the two-dimensional flood region at time step and flow rate , , respectively representing the second-dimensional generalized region Within each grid, the vertical distance from the floodwater surface to the bed surface (i.e., ,in The water level of this grid. (This refers to the bed elevation of the grid) and the flood in the x-direction of the Cartesian coordinate system. , y direction The velocity component; S33. Based on downstream topographic data, arrange several pre-defined downstream cross-sections (e.g., cross-sections at 1km, 5km, and 10km from the dam site) along the downstream river channel as extraction nodes for hydrodynamic elements. Then, based on the one-dimensional river channel model, in the... The calculation results of the time step are used to extract the flow rate time series and water level time series of the downstream preset section at the corresponding time step, thus obtaining the flow rate sequence of the downstream preset section. Specifically, this means that any preset section downstream is at the first... Real-time flow and downstream preset section water level sequence at time step Specifically, this means that any preset section downstream is at the first... Real-time water level at time step; S34. If the synchronization satisfies the first two-dimensional computational domain... The grid in the first Submerged water depth over time steps Greater than or equal to the preset effective flood depth threshold ( An effective inundation threshold of 0.1m is used in flood control engineering. This threshold is based on the minimum water depth for effective inundation stipulated in the Flood Control Standard GB50201-2014. The two-dimensional computational grid must have at least one effective connectivity path connecting the one-dimensional river channel to the boundary grid of the two-dimensional computational domain. This method determines the flood inundation range within the two-dimensional computational domain. It not only filters grids with physical inundation significance through the water depth threshold but also ensures that the inundation range matches the hydrodynamic process of flood evolution through hydrodynamic connectivity constraints. This improves the accuracy of inundation range determination compared to the traditional single threshold method. S35. By combining the real-time water level of the downstream section of the one-dimensional river channel, the inundation depth of the two-dimensional floodplain grid is dynamically corrected. By introducing dynamic constraints on the river channel water level, the floodplain inundation depth can respond to the rise or fall of the river flood, reducing its deviation from the actual inundation depth. Furthermore, based on the velocity components of the two-dimensional floodplain grid and combined with floodplain topographic parameters, the approach velocity of the flood is corrected, achieving a coupled representation of topographic resistance and hydrodynamic state, thus improving the accuracy of the two-dimensional floodplain approach velocity prediction results. The correction formula is as follows: In the above formula, This represents the flooding depth of the corrected two-dimensional flooding grid. This represents the water depth of each grid cell in the two-dimensional flood region. This represents the hydrodynamic correction coefficient, characterizing the influence of the river channel hydrodynamic state on the floodplain water depth. It is obtained from watershed hydrological data based on a standard dataset (value range: 0.05~0.1). This represents the average water level at the downstream river cross-section, specifically the average water level at all preset downstream cross-sections during the simulation period. This represents the flood approach velocity of the corrected two-dimensional flood grid, specifically the second-order flood approach velocity of the two-dimensional flood grid. Each grid in The actual speed of flood advance over time (reflecting the combined effects of topographic resistance and hydrodynamics). This represents the topographic resistance coefficient, specifically characterizing the amplification factor of topographic resistance on approach flow velocity. It is obtained from watershed hydrological data in a standard dataset (value range: 1.2~1.5). This represents the roughness coefficient of the two-dimensional overlay mesh, specifically characterizing the roughness coefficient of the second-order overlay mesh in the two-dimensional overlay. The resistance characteristics of the underlying surface (such as farmland and forestland) to floods in each grid, and the roughness parameters corresponding to the two-dimensional flood zone land use types in the downstream topographic data of the standard dataset (e.g., the roughness of farmland is 0.035). This represents the terrain slope of the two-dimensional flooded grid, specifically the slope of the second two-dimensional flooded grid. The bed surface elevation gradient of each grid, representing the degree of terrain undulation, is a grid gradient value calculated based on downstream terrain data of a standard dataset. S36. Obtain time series data of flow and water level at a preset cross-section of the downstream river channel, and flood inundation elements including flood inundation range, inundation depth, and flood approach velocity.

[0012] Furthermore, step S4 specifically includes the following steps: S41. Based on the flow rate and water level of the downstream river channel preset section, the flow rate and water level dual peak value collaborative determination is adopted. If the time step when the flow rate of the downstream preset section reaches the peak value is equal to the time step corresponding to the maximum value of the flow rate time series data and the maximum value of the water level sequence of the downstream preset section is within the preset water level peak value range, the arrival time of the flood peak of the downstream preset section is determined. The expression is: In the above formula, This indicates the arrival time of the flood peak at the downstream preset cross-section. Specifically, it is the model calculation time step corresponding to when the flood flow reaches its peak value and the water level is within the peak range at the downstream preset cross-section. This represents the time step corresponding to the peak value of the downstream preset cross-sectional flow sequence, and the time step at which the downstream preset cross-sectional flow sequence reaches its maximum value. This indicates the flow sequence at the downstream preset section. This indicates the water level sequence at the downstream preset cross-section. This indicates the peak water level at the downstream preset section. This represents the threshold value for the peak water level range at the downstream preset cross-section, characterizing the reasonable fluctuation range of the peak water level. It is used to avoid interference from single water level fluctuations in flood peak determination, and is set to 0.2 (based on flood control engineering practice). The peak water level range is... ; S42. Based on the peak flow rate at the downstream preset cross-section and the cross-sectional area, calculate the maximum average flood velocity at the downstream preset cross-section according to the ratio of the peak flow rate to the cross-sectional area. The peak flow rate is the maximum value of the cross-sectional flow sequence. The cross-sectional area is derived from the river cross-section data in the downstream topographic data of the standard dataset. This addresses the technical shortcomings of traditional methods that rely solely on velocity components to calculate the average velocity, without considering the actual cross-sectional area, leading to significant deviations between the calculated results and the actual hydrodynamic state. S43. Using the downstream pre-defined cross-section as the spatial center and a pre-defined threshold (e.g., 500m) as the radius, delineate a set of two-dimensional flood zone grids to determine the flood zone influence range corresponding to the downstream pre-defined cross-section. Extract the corrected inundation depth of all grids within the two-dimensional flood zone influence range, and take the maximum value as the maximum inundation depth of the flood zone corresponding to the downstream pre-defined cross-section. By establishing the spatial coupling relationship between the downstream river cross-section and the flood zone, the matching degree between the two-dimensional flood zone inundation depth and the corresponding cross-section flood process is improved, providing accurate depth quantification basis for flood risk assessment of the cross-section influence area. The calculation formula is as follows: In the above formula, This indicates the maximum flood depth of the flood zone corresponding to the downstream section. This indicates the submerged water depth of the corrected two-dimensional flooding grid. Indicates the two-dimensional over-region grid calculation number. Indicates the flood zone impact range corresponding to the downstream section; S44, to obtain the comprehensive analysis results of dam-break floods, including the peak arrival time of the downstream preset section, the maximum average flow velocity of the flood at the downstream preset section, and the maximum inundation depth of the floodplain corresponding to the downstream preset section.

[0013] By employing the above technical solution, the present invention provides a method for analyzing the evolution of rigid dam break floods, which has at least the following beneficial effects: 1. This invention dynamically matches the computational step size of the one-dimensional river channel model and the two-dimensional flood zone model by adaptive time step, thereby improving the convergence rate of the coupled simulation and enhancing the stability of the one-dimensional coupled simulation. It effectively avoids the problems of numerical oscillation or divergence and excessive computation time caused by the traditional fixed step size, improves computational efficiency, and can quickly complete the simulation of dam-break flood evolution under multiple working conditions.

[0014] 2. This invention constructs a dynamic water exchange mechanism between the river channel and the floodplain through bidirectional interaction of lateral flux, realizing dynamic water exchange feedback between the river channel and the floodplain, improving the matching degree of hydrodynamic parameters between the river channel and the floodplain, solving the defect of discontinuous evolution process caused by traditional unidirectional data input, providing more realistic numerical support for dynamic simulation of dam-break floods across the entire area, and enhancing the matching degree of hydrodynamic processes between the river channel and the floodplain.

[0015] 3. This invention reduces the error in determining the arrival time of flood peaks and the maximum average flow velocity by combining the dynamic coupling correction of flood inundation elements and river hydrodynamic state, reduces the simulation deviation of the maximum inundation depth of flood areas, and improves the consistency of characteristic parameters and the calculation accuracy of flood characteristic parameters and inundation elements. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of the evolution analysis of the present invention. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This will allow for a full understanding of how the present application uses technical means to solve technical problems and achieve technical effects, and to facilitate its implementation.

[0018] In current coupled models, the spatial boundaries between the one-dimensional channel and the two-dimensional floodplain are often simply spliced ​​together, and the computation time steps are set independently, lacking a synchronization and coordination mechanism, which affects the accuracy of dam-break flood evolution simulation. To achieve adaptive synchronization of the time steps between the one-dimensional channel model and the two-dimensional floodplain model, and to improve the convergence rate and computational efficiency of the coupled simulation, this implementation proposes a rigid dam dam-break flood evolution analysis method, such as... Figure 1 As shown, the method includes the following steps: S1. Collect multi-source datasets related to the evolution of rigid dam break floods. Perform standardization preprocessing on the acquired multi-source datasets to obtain a standard dataset, which is used to eliminate data heterogeneity and improve data quality. The standard dataset includes dam structure data, watershed hydrological data, and downstream topographic data. Dam structure data is the fundamental data characterizing the structural characteristics and breach parameters of a rigid dam. It includes dam type (the structural type of a rigid dam, such as a gravity dam or an arch dam), total dam length (the overall length of the dam or the length of the spillway area, used to determine the breach width in a scenario of instantaneous total breach), spillway crest width (the effective width of the spillway cross section), spillway crest elevation (the elevation of the spillway crest), and breach sub-data. The breach sub-data includes at least the breach flow coefficient (derived from a coefficient obtained through standard settings and experimental calibration, used for dam breach flow calculation) and breach width (the breach width during the dam breach process).

[0019] Watershed hydrological data are fundamental data characterizing the hydrological characteristics and channel resistance characteristics of the upstream watershed of a dam breach. These include average watershed rainfall (average rainfall measured by rain gauges in the watershed during a preset time period (e.g., 24 hours) before the dam breach), watershed catchment area (the catchment area of ​​the reservoir where the rigid dam is located), watershed steady infiltration rate (the steady infiltration rate of the watershed soil), watershed initial loss (the amount of rainfall used to meet vegetation interception and initial soil infiltration during the initial rainfall period), and channel roughness coefficient (characterizing the resistance characteristics of the channel bed or bank to water flow).

[0020] Downstream topographic data is the basic data characterizing the topographic features of the downstream river channel and floodplain after a dam break. It includes river channel cross-section data (design water flow area of ​​the downstream river channel's preset cross-section), river channel cross-section elevation (elevation value of the downstream river channel's preset cross-section), riverbed elevation (elevation value of the downstream riverbed relative to a unified elevation datum), and floodplain boundary data (spatial boundary range of the downstream floodplain).

[0021] The process of calculating the inflow flood and the flood regulation calculation are completed sequentially to obtain the dam-break flood process at the dam site. This is achieved by first calculating the time evolution of the inflow flood, then completing the flood regulation calculation based on the reservoir water balance and flood discharge patterns, and finally obtaining the flow time series of the dam-break flood at the dam site. The specific steps include the following: S11. Based on the watershed hydrological data in the standard dataset, calculate the net rainfall depth and inflow flood discharge in the watershed for any given time period. This represents the time-varying process of the flood discharge flowing into the reservoir, providing the upstream input boundary for flood control calculations. This ensures that the flood control calculations match the actual inflow characteristics of the watershed, thus obtaining the inflow flood process. The calculation formula is as follows: In the above formula, Indicates the first Net rainfall depth in the basin during the period Indicates the first The average rainfall over a given period, specifically the rainfall measured at rain gauge stations within the basin during that period. This represents the initial watershed loss, specifically the amount of rainfall used in the early stages of precipitation to meet the needs of vegetation interception and initial soil infiltration. This represents the steady-state infiltration rate of a watershed, specifically the stable rate of rainwater infiltration after the watershed soil reaches saturation. Indicates the length of the calculation period. Indicates the first Inflow of floodwater during a given period This refers to the catchment area of ​​a watershed, specifically the catchment area of ​​the reservoir where the rigid dam is located. Indicates the first The net rainfall depth in the basin during each rainfall period Represents the ordinate of the unit hydrograph in the watershed, specifically characterizing the first... Net rainfall per unit time period in the first The proportion of convergence response formed during the time period This indicates a unit conversion factor used to unify the dimensions of rainfall, area, and flow rate. S12, according to the first Using inflow flood discharge and dam structure data for a given period, and employing the reservoir water balance equation and flood discharge formula, the total inflow, total outflow, and outflow flood discharge for any given period are calculated to complete the flood control calculation. The calculation formulas are as follows: In the above formula, Indicates the first Total water inflow during the period Indicates the first Total water outflow during the period Indicates the initial water storage of the reservoir during the period, the first... The water level in the reservoir at the end of the period. This indicates the reservoir's water storage at the end of the time period, the first... The water level in the reservoir at the end of the period. Indicates the first Outflow of floodwater during a given period This represents the spillway flow coefficient, a coefficient reflecting the spillway's discharge efficiency, with a value ranging from 0.35 to 0.55. This indicates the width of the spillway crest, specifically the effective width of the spillway's discharge cross-section. Represents gravitational acceleration. Indicates the first Water level in front of the dam during the specified time period This indicates the elevation of the spillway crest, specifically the altitude of the spillway crest. S13. Assuming the rigid dam experiences instantaneous total failure, based on the flood control calculations... Using data on the upstream water level and dam structure for any given time period, the dam-break flood discharge at the dam site is calculated. This represents the time-varying process of the dam-break flood discharge at the dam site, thus obtaining the dam-break flood process at the dam site. This data forms the upstream input boundary data for the subsequent one-dimensional coupled model. The calculation formula is as follows: In the above formula, Indicates the first The dam-break flood discharge at the dam site during a given period is a quantitative indicator of the dam-break flood process at the dam site. This represents the breach flow coefficient, a coefficient used to reflect the breach discharge efficiency (determined based on dam material and breach shape data from a standard dataset, with a value range of 0.5 to 0.7). Indicates the first The breach width during a given period; the breach width during a dam breach is equal to the total length of the dam's overflow section. This indicates the elevation of the bottom of the weir.

[0022] S2. Based on downstream topographic data, construct a one-dimensional river channel model to characterize flood propagation along the river course, and a two-dimensional computational domain model to characterize the planar flood diffusion in the floodplain. Through a coupling interface, achieve spatial boundary matching, time step synchronization, and flow and water level data exchange between the one-dimensional and two-dimensional models to obtain a coupled one-dimensional model. This model can support the characterization of flood evolution characteristics in different regions, ensuring stable and efficient synchronous model calculation. Specifically, the steps include: S21. Using the river centerline as the axis, a one-dimensional grid is generated using equidistant segmentation and a terrain abrupt change densification strategy to obtain the spacing between each grid node. The cross-sectional area and hydraulic radius of the river channel are extracted from the downstream topographic data. With the dam-break flood discharge at the dam site as the upstream input boundary, based on the Saint-Venant equations and the propagation characteristics along the river, and using the finite volume method for discretization, the one-dimensional hydrodynamic governing equations are obtained, as expressed below: In the above formula, This represents the cross-sectional area of ​​the river channel, specifically the cross-sectional area occupied by the water flow at any section of the river channel, obtained from the river channel cross-sectional elevation in the downstream topographic data. This represents the cross-sectional flow rate of a river channel, specifically the volume of water passing through any cross-section of the channel per unit time. It is obtained by taking the dam-break flood discharge at the dam site as the upstream input boundary, and combining it with downstream topographic data, through the Saint-Venant equations. It is the result of flood propagation and energy dissipation along the river's course. This represents the lateral flow rate per unit width, specifically the rate of lateral water exchange per unit length of river channel. It represents the momentum flux per unit mass of water flow, characterizing the momentum transfer characteristics of water flow at a cross section. Indicates the water level at the river cross-section. Represents gravitational acceleration. This refers to the slope of the riverbed, specifically the gradient of the riverbed along its axial direction. The roughness coefficient represents the resistance characteristics of the riverbed or bank to water flow; it is derived from watershed hydrological data. The hydraulic radius is the ratio of the cross-sectional area to the wetted perimeter, which is the circumference of the water flow in contact with the riverbank. It is calculated from the cross-section of the river channel based on downstream topographic data. S22. Extract the boundary data of the flood region, extend it outward by a preset threshold (which can be set to 5%) as a buffer zone (to avoid boundary effects) to form a two-dimensional computational domain, and generate an unstructured triangular mesh. Ensure that the minimum interior angle of the triangular mesh is ≥30°, the maximum interior angle is ≤120°, and the mesh distortion rate is ≤15% to obtain the mesh cell size. Based on the shallow water equations and planar diffusion characteristics, use the finite volume method to discretize and solve the one-dimensional hydrodynamic governing equations, as shown in the following expression: In the above formula, This represents water depth, the vertical distance from the floodwater surface to the bed surface at any given location; it is the difference between the water level (the elevation of the floodwater surface at that location) and the bed elevation (the elevation of the natural bottom surface at that location). Indicates time, Indicates water flow at Flow velocity component in the direction, Indicates the bed surface is The slope in the direction is calculated from the riverbed elevation in the downstream topographic data of the standard dataset. Indicates the friction slope at Components in direction, Indicates water flow at Flow rate per unit width in the direction; in, , Indicates the elevation of the riverbed; , , This represents the roughness coefficient of the river channel.

[0023] S23. Extract feature points of the one-dimensional river boundary (such as shoreline turning points and slope change points) and topographic feature points of the two-dimensional flood zone (such as elevation change points and land use type boundary points). The feature point density is positively correlated with the grid cell size. Based on the feature points of the one-dimensional river boundary, extend to the direction of the two-dimensional flood zone to generate a coupled overlapping area. Map the feature points of the one-dimensional river boundary with the grid nodes of the two-dimensional coupled overlapping area. S24. Based on the minimum grid node spacing of the one-dimensional model and the minimum grid cell side length of the two-dimensional model, obtain the stable time step of the one-dimensional model and the two-dimensional model, and generate a unified time step of the coupled model to improve the computational convergence rate and computational efficiency of the coupled model. S25. Based on the water level difference and topographic slope of the overlapping area of ​​the one-dimensional and two-dimensional models, calculate the lateral unit width flow at the boundary between the one-dimensional channel model and the two-dimensional floodplain model. Feed back to the Saint-Venant equations of the one-dimensional channel model and the shallow water equations of the two-dimensional floodplain model as boundary input conditions of the other model. Complete a data interaction once within each unified time step to realize the dynamic adaptation between the one-dimensional channel model and the two-dimensional computational domain model and generate a one-dimensional and two-dimensional coupled model. The formula for calculating the lateral unit width discharge of the river channel and floodplain is as follows: In the above formula, It represents the lateral flow rate per unit width, specifically the rate of water exchange between the river channel and the floodplain per unit length. This represents the hydraulic exchange coefficient, which characterizes the hydraulic connectivity of the connecting zone (it can take values ​​from 0.8 to 1.0). This represents the water level at the boundary nodes of the one-dimensional model, specifically the real-time water level at the boundary nodes connecting the one-dimensional river channel model and the two-dimensional floodplain. This represents the water level at the boundary grid of the two-dimensional model, specifically the real-time water level at the boundary grid connecting the two-dimensional floodplain model and the river channel. It represents the slope angle of the connecting area, specifically the angle between the slope of the connecting area and the boundary, and characterizes the degree of matching of the water flow direction.

[0024] S3. Using the dam-break flood process at the dam site as the boundary condition, a dynamic evolution simulation of the dam-break flood flow at the dam site is performed based on a one-dimensional coupled model. This yields the flow and water level at the preset cross-section of the downstream river channel, as well as the flood inundation elements within the two-dimensional computational domain. The flood inundation elements include the inundation range, water depth, and approach velocity. This addresses the technical shortcomings of traditional flood evolution simulations, such as poor adaptability of boundary conditions, asynchronous time steps, and the lack of lateral water exchange mechanisms. It improves the convergence rate and computational efficiency of the coupled simulation. The specific steps include the following: S31. Extract the flood flow sequence at the dam site and perform linear interpolation to make its time step consistent with the unified time step of the one-dimensional coupled model, so as to obtain the boundary flow sequence adapted to the one-dimensional coupled model, ensuring the temporal accuracy of the boundary conditions. Set the boundary flow sequence as the upstream input boundary of the one-dimensional river channel model and synchronize it to the near-dam boundary of the two-dimensional computational domain model through the coupling interface. S32. Solve the Saint-Venant equations based on the boundary flow sequence and a one-dimensional river channel model. The one-dimensional river channel model is discretized longitudinally, with the downstream channel along its axis (longitudinal coordinate). The node is divided into several discrete nodes, labeled as follows: The vertical coordinates of the nodes are In the Water levels at each node of the one-dimensional river channel at the next time step and traffic , respectively representing the first dimension of the river channel The flood water level at each node and the passage of the one-dimensional river channel per unit time. The flood discharge corresponding to each node is calculated. Based on the lateral flux feedback from the coupling interface and combined with the two-dimensional computational domain model, the corrected shallow water equations are solved. The two-dimensional floodplain model adopts a planar discretization method, dividing the downstream floodplain into several triangular computational grids. Let the first node be denoted as _____. The grid numbers are In the Water depth of each grid in the two-dimensional flood region at time step and flow rate , , respectively representing the second-dimensional generalized region Within each grid, the vertical distance from the floodwater surface to the bed surface (i.e., ,in The water level of this grid. (This refers to the bed elevation of the grid) and the flood in the x-direction of the Cartesian coordinate system. , y direction The velocity component; S33. Based on downstream topographic data, arrange several pre-defined downstream cross-sections (e.g., cross-sections at 1km, 5km, and 10km from the dam site) along the downstream river channel as extraction nodes for hydrodynamic elements. Then, based on the one-dimensional river channel model, in the... The calculation results of the time step are used to extract the flow rate time series and water level time series of the downstream preset section at the corresponding time step, thus obtaining the flow rate sequence of the downstream preset section. Specifically, this means that any preset section downstream is at the first... Real-time flow and downstream preset section water level sequence at time step Specifically, this means that any preset section downstream is at the first... Real-time water level at time step; S34. If the synchronization satisfies the first two-dimensional computational domain... The grid in the first Submerged water depth over time steps Greater than or equal to the preset effective flood depth threshold ( An effective inundation threshold of 0.1m is used in flood control engineering. This threshold is based on the minimum water depth for effective inundation stipulated in the Flood Control Standard GB50201-2014. The two-dimensional computational grid must have at least one effective connectivity path connecting the one-dimensional river channel and the boundary grid of the two-dimensional computational domain. This method determines the flood inundation range within the two-dimensional computational domain. It not only filters grids with physical inundation significance through the water depth threshold but also ensures that the inundation range matches the hydrodynamic process of flood evolution through hydrodynamic connectivity constraints. This improves the accuracy of inundation range determination compared to the traditional single threshold method. S35. By combining the real-time water level of the downstream section of the one-dimensional river channel, the inundation depth of the two-dimensional floodplain grid is dynamically corrected. By introducing dynamic constraints on the river channel water level, the floodplain inundation depth can respond to the rise or fall of the river flood, reducing its deviation from the actual inundation depth. Furthermore, based on the velocity components of the two-dimensional floodplain grid and combined with floodplain topographic parameters, the approach velocity of the flood is corrected, achieving a coupled representation of topographic resistance and hydrodynamic state, thus improving the accuracy of the two-dimensional floodplain approach velocity prediction results. The correction formula is as follows: In the above formula, This represents the flooding depth of the corrected two-dimensional flooding grid. This represents the water depth of each grid cell in the two-dimensional flood region. This represents the hydrodynamic correction coefficient, characterizing the influence of the river channel hydrodynamic state on the floodplain water depth. It is obtained from watershed hydrological data based on a standard dataset (value range: 0.05~0.1). This represents the average water level at the downstream river cross-section, specifically the average water level at all preset downstream cross-sections during the simulation period. This represents the flood approach velocity of the corrected two-dimensional flood grid, specifically the second-order flood approach velocity of the two-dimensional flood grid. Each grid in The actual speed of flood advance over time (reflecting the combined effects of topographic resistance and hydrodynamics). This represents the topographic resistance coefficient, specifically characterizing the amplification factor of topographic resistance on approach flow velocity. It is obtained from watershed hydrological data in a standard dataset (value range: 1.2~1.5). This represents the roughness coefficient of the two-dimensional overlay mesh, specifically characterizing the roughness coefficient of the second-order overlay mesh in the two-dimensional overlay. The resistance characteristics of the underlying surface (such as farmland and forestland) to floods in each grid, and the roughness parameters corresponding to the two-dimensional flood zone land use types in the downstream topographic data of the standard dataset (e.g., the roughness of farmland is 0.035). This represents the terrain slope of the two-dimensional flooded grid, specifically the slope of the second two-dimensional flooded grid. The bed surface elevation gradient of each grid, representing the degree of terrain undulation, is a grid gradient value calculated based on downstream terrain data of a standard dataset. S36. Obtain time series data of flow and water level at a preset cross-section of the downstream river channel, and flood inundation elements including flood inundation range, inundation depth, and flood approach velocity.

[0025] S4. Based on the flow and water level time series of the downstream river channel's preset cross-section and the flood inundation elements in the two-dimensional computational domain, calculate the peak arrival time, maximum average flow velocity, and maximum inundation depth of the downstream preset cross-section, generating comprehensive analysis results of dam-break floods. This includes the following steps: S41. Based on the flow and water level time series of the downstream river channel's preset cross-section, a dual-peak determination of flow and water level is adopted. If the time step when the flow reaches its peak at the downstream preset cross-section is equal to the time step corresponding to the maximum value of the flow time series data, and the maximum value of the water level sequence at the downstream preset cross-section is within the preset water level peak range, the arrival time of the flood peak at the downstream preset cross-section is determined to ensure the time matching degree between the determination result and the actual flood evolution. The calculation formulas for the arrival time of the flood peak at the downstream preset cross-section and the water level sequence at the downstream preset cross-section are as follows: In the above formula, This indicates the arrival time of the flood peak at the downstream preset cross-section. Specifically, it is the model calculation time step corresponding to when the flood flow reaches its peak value and the water level is within the peak range at the downstream preset cross-section. This represents the time step corresponding to the peak value of the downstream preset cross-sectional flow sequence, and the time step at which the downstream preset cross-sectional flow sequence reaches its maximum value. This indicates the flow sequence at the downstream preset section. This indicates the water level sequence at the downstream preset cross-section. This indicates the peak water level at the downstream preset section. This represents the threshold value for the peak water level range at the downstream preset cross-section, characterizing the reasonable fluctuation range of the peak water level. It is used to avoid interference from single water level fluctuations in flood peak determination, and is set to 0.2 (based on flood control engineering practice). The peak water level range is... ; S42. In order to solve the technical defects of traditional methods that rely solely on velocity components to calculate average velocity and do not take into account the actual cross-sectional area, resulting in a large deviation between the calculation results and the actual hydrodynamic state, the maximum average flow velocity of the downstream preset cross-section is calculated based on the peak flow rate of the downstream preset cross-section and the cross-sectional area of ​​the cross-section. The peak flow rate of the cross-section is the maximum value of the cross-sectional flow sequence. The cross-sectional area of ​​the cross-section is derived from the river cross-section data in the downstream topographic data of the standard dataset, so that the results are consistent with the actual flow state of the river. S43. Using the downstream preset cross-section as the spatial center and a preset threshold (e.g., 500m) as the radius, delineate a set of two-dimensional flood zone grids, determine the flood zone influence range corresponding to the downstream preset cross-section, and extract the corrected inundation depth of all grids within the two-dimensional flood zone influence range. Take the maximum value as the maximum flood zone inundation depth corresponding to the downstream preset cross-section, thus realizing the dynamic correlation between the flood zone inundation depth and the flood process of the corresponding cross-section, and improving the relevance of the results. By establishing the spatial coupling relationship between the downstream river section and the floodplain, the matching degree between the two-dimensional floodplain inundation depth and the corresponding flood process at the section is improved, providing a precise quantitative basis for flood control risk assessment of the affected area. The calculation formula is as follows: In the above formula, This indicates the maximum flood depth of the flood zone corresponding to the downstream section. This indicates the submerged water depth of the corrected two-dimensional flooding grid. Indicates the two-dimensional over-region grid calculation number. Indicates the flood zone impact range corresponding to the downstream section; S44. Obtain the comprehensive analysis results of dam-break floods, including the arrival time of the flood peak at the downstream preset section, the time node representing the flood threat, the maximum average flow velocity of the flood at the downstream preset section, the risk of scouring and damaging the river channel engineering by the flood, and the maximum inundation depth of the floodplain corresponding to the downstream preset section, which represents the degree of flood threat to the floodplain. This solves the technical defect of traditional analysis results that only focus on a single dimension and cannot comprehensively represent the comprehensive risk of floods.

[0026] This evolutionary analysis method acquires and preprocesses multi-source datasets of rigid dams to obtain a standard dataset, and then sequentially performs inflow flood process calculations and flood regulation calculations to obtain the dam-break flood process at the dam site. Combined with downstream topographic data, a one-dimensional river channel model and a two-dimensional computational domain model are constructed. Through a coupling interface, the spatial boundary matching, time step synchronization, and flow and water level data interaction between the one-dimensional and two-dimensional models are achieved to obtain a one-dimensional and two-dimensional coupled model. Then, using the dam-break flood process at the dam site as the boundary condition, the dynamic evolution simulation of the dam-break flood flow at the dam site is performed based on the one-dimensional and two-dimensional coupled model to obtain the flow and water level of the downstream river channel at a preset cross-section and the flood inundation elements in the two-dimensional computational domain. This allows for the calculation of the peak arrival time, maximum average flow velocity, and maximum inundation depth at the downstream preset cross-section, generating comprehensive analysis results of the dam-break flood and achieving full-dimensional quantification of dam-break flood risk.

[0027] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0028] The above embodiments have provided a detailed description of the present invention. For those skilled in the art, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A rigid dam-break flood routing analysis method, characterized by, The method includes the following steps: S1. Obtain and preprocess the multi-source dataset of the rigid dam to obtain the standard dataset, and sequentially complete the inflow flood process calculation and flood regulation calculation to obtain the dam break flood process at the dam site; S2. Construct a one-dimensional river channel model and a two-dimensional computational domain model based on downstream topographic data. Use a coupling interface to achieve spatial boundary matching, time step synchronization and flow and water level data interaction between the one-dimensional and two-dimensional models to obtain a one-dimensional coupled model. S3. Using the dam break flood process at the dam site as the boundary condition, the dynamic evolution of the dam break flood flow at the dam site is simulated based on a one-dimensional coupled model to obtain the flow and water level of the downstream river channel at the preset cross section, as well as the flood inundation elements in the two-dimensional computational domain. S4. Based on the flow rate and water level of the downstream river channel at the preset cross-section and the flood inundation factors, calculate the peak arrival time, maximum average flow velocity, and maximum inundation depth of the downstream preset cross-section, and generate the comprehensive analysis results of the dam-break flood.

2. The method of claim 1, wherein, The standard dataset includes dam structure data, watershed hydrological data, and downstream topographic data; The dam structure data includes dam type, total dam length, spillway crest width, spillway crest elevation, and breach sub-data; and the breach sub-data includes at least the breach flow coefficient and breach width. The watershed hydrological data includes average rainfall, catchment area, steady infiltration rate, initial loss, and channel roughness coefficient. The downstream topographic data includes river channel cross-section data, river channel cross-section elevation, riverbed elevation, and floodplain boundary data.

3. The method of claim 2, wherein, Step S1 specifically includes the following steps: S11. Assuming the rigid dam experiences instantaneous total failure, calculate the net rainfall depth and inflow flood discharge for any given time period based on the watershed hydrological data from the standard dataset to obtain the inflow flood process. The calculation formula is as follows: In the above formula, the first the net rainfall depth of the watershed in the time period, the first the average rainfall of the watershed in the time period, the first the steady infiltration rate of the watershed, the first the length of the calculation time period, the first the catchment area of the watershed, the first the net rainfall depth of the watershed generated in the rainfall period, the first the unit conversion coefficient; S12, according to the first Based on the inflow flood discharge and dam structure data for a given period, calculate the total inflow water volume, total outflow water volume, and outflow flood discharge for any given period to complete the flood control calculation. The calculation formula is as follows: In the above formula, Indicates the first Total inflow of water during the period Indicates the first Total water outflow during the period This indicates the initial water storage capacity of the reservoir during the specified period. This indicates the reservoir's water storage at the end of the period. Indicates the first Outflow of floodwater during a given period Indicates the spillway flow coefficient. Indicates the width of the spillway crest. Represents gravitational acceleration. Indicates the first Water level in front of the dam during the specified time period Indicates the elevation of the spillway crest; S13. Based on the dam front water level and dam structure data for any given time period obtained from flood control calculations, calculate the dam-break flood flow at the dam site for any given time period, and obtain the dam-break flood process at the dam site. The calculation formula is as follows: In the above formula, Indicates the first The flow rate of the dam breach at the dam site during the specified period. Indicates the dam-break flow coefficient. Indicates the width of the ulcer. This indicates the elevation of the bottom of the weir.

4. The evolutionary analysis method according to claim 1, characterized in that, Step S2 specifically includes the following steps: S21. Using the river centerline as the axis, a one-dimensional grid is generated by equidistant segmentation and topographic abrupt change point densification strategy to obtain the spacing between each grid node. The cross-sectional area and hydraulic radius of the river channel in the downstream topographic data are extracted. The dam break flood flow at the dam site is taken as the upstream input boundary. Based on the Saint-Venant equations and the propagation characteristics along the route, the one-dimensional hydrodynamic control equations are obtained by discretizing and solving using the finite volume method. S22. Extract the boundary data of the flood region, extend it outward with a preset threshold as a buffer zone to form a two-dimensional computational domain, and generate a triangular mesh to obtain the mesh cell size. Based on the shallow water equations and planar diffusion characteristics, use the finite volume method to discretize and solve the two-dimensional hydrodynamic control equations. S23. Extract the feature points of the one-dimensional river boundary and the terrain feature points of the two-dimensional flood zone. Using the feature points of the one-dimensional river boundary as a reference, extend the two-dimensional flood zone to generate a coupled overlapping area. Map the feature points of the one-dimensional river boundary to the grid nodes of the two-dimensional coupled overlapping area. S24. Based on the minimum grid node spacing of the one-dimensional model and the minimum grid cell side length of the two-dimensional model, obtain the stable time step of the one-dimensional model and the two-dimensional model, and generate the unified time step of the coupled model. S25. Based on the water level difference and topographic slope of the overlapping area coupled by the one-dimensional and two-dimensional models, the lateral unit width flow of the river channel and the floodplain is obtained. The flow is fed back to the Saint-Venant equations of the one-dimensional river channel model and the shallow water equations of the two-dimensional floodplain model, respectively. Data interaction is completed once within each unified time step to realize the dynamic adaptation between the one-dimensional river channel model and the two-dimensional computational domain model, and generate a one-dimensional and two-dimensional coupled model.

5. The evolutionary analysis method according to claim 4, characterized in that, The expression for the one-dimensional hydrodynamic governing equation is as follows: In the above formula, Indicates the cross-sectional area of ​​the river channel. Indicates the cross-sectional flow rate of the river channel. Indicates lateral unit width flow rate. This represents the momentum flux per unit mass of water flow. Indicates the water level at the river cross-section. Represents gravitational acceleration. Indicates the riverbed slope. This represents the river channel roughness coefficient. Indicates the hydraulic radius.

6. The evolutionary analysis method according to claim 5, characterized in that, The expression for the two-dimensional hydrodynamic governing equations is as follows: In the above formula, Indicates water depth. Indicates time, Indicates water flow at Flow velocity component in the direction, Indicates the bed surface is Slope in direction, Indicates the friction slope at Components in direction, Indicates water flow at Flow rate per unit width in the direction; in, Indicates the elevation of the riverbed. This represents the roughness coefficient of the river channel.

7. The evolutionary analysis method according to claim 1, characterized in that, In step S3, the flood inundation elements include the inundation range, water depth, and approach current velocity, specifically including the following steps: S31. Extract the flood discharge sequence at the dam site and perform linear interpolation to make its time step consistent with the unified time step of the one-dimensional coupled model to obtain the boundary discharge sequence. Set the boundary discharge sequence as the upstream input boundary of the one-dimensional river channel model and synchronize it to the near-dam boundary of the two-dimensional computational domain model through the coupling interface. S32. Based on the boundary flow sequence and combined with a one-dimensional river channel model using a longitudinal discretization method, the downstream river channel is divided into several discrete nodes along its axis, labeled as follows: The vertical coordinates of the nodes are , obtained in the first Water levels at each node of the one-dimensional river channel at the next time step and traffic Based on the lateral flux feedback from the coupling interface and combined with a two-dimensional computational domain model using a planar discretization method, the downstream flood region is divided into several triangular computational grids, denoted as the first... The grid numbers are , obtained in the first Water depth of each grid in the two-dimensional flood region at time step and flow rate , ; S33. Based on downstream topographic data, several pre-defined downstream cross-sections are arranged along the downstream river channel to serve as extraction nodes for hydrodynamic elements. According to the one-dimensional river channel model, in the... The calculation results of the time steps yield the flow sequence of the downstream preset section at the corresponding time step. and the water level sequence of the downstream preset section ; S34. If the synchronization satisfies the first two-dimensional computational domain... The grid in the first Submerged water depth over time steps Greater than or equal to the preset effective flood depth threshold Furthermore, the two-dimensional computational grid has at least one valid connection path to the boundary grid connecting the one-dimensional river channel and the two-dimensional computational domain, thereby determining the flood inundation range within the two-dimensional computational domain; S35. Combine the real-time water level of the downstream section of the one-dimensional river channel to dynamically correct the inundation depth of the two-dimensional floodplain grid, and based on the velocity component of the two-dimensional floodplain grid and combined with the floodplain topographic parameters, correct the approach velocity of the flood. S36. Obtain the time series of flow and water level at the preset cross-section of the downstream river channel and the flood inundation elements including the flood inundation range, inundation depth and flood approach velocity.

8. The evolutionary analysis method according to claim 1, characterized in that, Step S4 specifically includes the following steps: S41. Based on the flow rate and water level of the downstream river channel preset section, the flow rate and water level dual peak value collaborative determination is adopted. If the time step when the flow rate of the downstream preset section reaches the peak value is equal to the time step corresponding to the maximum value of the flow rate time series data and the maximum value of the water level sequence of the downstream preset section is within the preset water level peak value range, the arrival time of the flood peak of the downstream preset section is determined. S42. Based on the peak flow rate of the downstream preset section and the water flow area of ​​the section, calculate the maximum average flow velocity of the flood at the downstream preset section according to the ratio of the peak flow rate of the downstream preset section to the water flow area of ​​the section. S43. Using the downstream preset cross section as the spatial center and the preset threshold as the radius, delineate a set of two-dimensional flood zone grids, determine the flood zone influence range corresponding to the downstream preset cross section, and extract the corrected flood depth of all grids within the two-dimensional flood zone influence range, taking the maximum value as the maximum flood depth of the flood zone corresponding to the downstream preset cross section. S44, to obtain the comprehensive analysis results of dam-break floods, including the peak arrival time of the downstream preset section, the maximum average flow velocity of the flood at the downstream preset section, and the maximum inundation depth of the floodplain corresponding to the downstream preset section.

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