Method and device for simulating flood after dam break of barrier dam

Abstract

The application provides a dam-break flood simulation method and device, wherein the method comprises the following steps: obtaining the elevation of the reservoir water level of the dam and other parameters, calculating a breach flow evolution curve and other curves, and converting point source data into surface source data; obtaining the calculation result of the flood simulation; sequentially calculating the physical quantity of each node in stages, using different time steps in each stage, changing the calculation parameters when entering the next stage, and updating the terrain data; using time series alignment technology to align the initial scale representative flow value output by the dam-break parameter model; calculating the river flow of the river in the dam-break area; obtaining a reservoir capacity-sediment coupling model according to the sediment mass conservation equation, and predicting the dam-break of the to-be-predicted area, so that the time series alignment technology effectively guarantees the cross-scale data transmission accuracy and makes up for the limitation that the traditional calculation model cannot simulate short-term breaches and short-term river scouring.

Description

Technical Field

[0001] This invention relates to the field of geological disaster prevention and control technology, and in particular to a method and apparatus for simulating floods after a landslide dam breach. Background Technology

[0002] After natural disasters such as landslides, mudslides, volcanic eruptions, or earthquakes occur, large amounts of soil, rocks, or lava block rivers, valleys, or canyons. As the blocked river water continues to rise, a landslide dam is formed. As a special type of natural dam, a landslide dam poses a huge risk as the river water continues to rise. Due to the unstable structure of the landslide dam, the dam may collapse as the water pressure increases. Once the landslide dam breaks, the huge amount of water accumulated in the landslide lake will pour down in a short period of time, forming a devastating flood that causes enormous damage to downstream villages, cities, and other infrastructure.

[0003] However, current research on landslide dam failure mainly focuses on calculating instantaneous breach parameters (such as breach width and peak flow) after the dam breaks, lacking simulations of post-break sediment transport, riverbed evolution, and long-term geomorphological feedback.

[0004] The current technology has the following main limitations:

[0005] (1) Time scale fragmentation: A single model is difficult to take into account both the transient flow at the moment of the outburst (minute level) and the cumulative effect of the riverbed during the sediment transport period (interannual);

[0006] (2) Decoupling of multiple physical processes: Existing coupled models (such as MIKE11-DB) have not realized the interaction of all elements of landslide dam failure, sediment transport and geomorphological evolution, resulting in insufficient accuracy of long-term flood diversion prediction.

[0007] (3) Existing models are difficult to calculate the changes in sediment erosion and deposition over long distances downstream caused by dam failure.

[0008] (4) It is difficult to improve the accuracy of cross-scale dam break calculation models, and numerical errors are easily generated when calculating from small scale to large scale.

[0009] It is evident that current technology, when dealing with the decoupling of dam body and river channel calculations, cannot calculate the gradual dam failure process of landslide dams under different hydraulic and lithological conditions. Furthermore, it can only simulate the scouring and deposition process of the riverbed during dam failure, but since the dam body and river channel are at a uniform small scale, it cannot calculate the results of river channel scouring and deposition over many years. It also cannot consider the impact of complex river channels. Summary of the Invention

[0010] The purpose of this invention is to provide a method and apparatus for simulating floods after a landslide dam breach, which can simulate the flood after the breach and the evolution of the river channel.

[0011] To address the aforementioned problems, a first aspect of the present invention provides a method for simulating floods after a landslide dam breach, comprising:

[0012] Step S10000: Obtain the elevation of the reservoir water level, the elevation of the breach bottom, the inflow rate into the reservoir, the initial breach width, and the erosion rate of the landslide dam. Based on the dam break parameter model, calculate the breach flow evolution curve, the suspended sediment transport concentration curve, and the reservoir water level decay curve. Based on the dynamic constraint cross-scale data bridging mechanism, use the spatiotemporal convolution kernel mapping algorithm to convert the breach flow evolution curve, the suspended sediment transport concentration spectrum, and the reservoir water level decay curve from point source data into area source data.

[0013] Step S20000: Based on the inverse AMR concept, a multi-level grid system is used to divide the dam-break area into a first-level grid, a second-level grid, and a third-level grid according to the grid size. The first-level grid is defined as the dam body area of ​​the landslide dam in the dam-break area; the second-level grid is defined as the sedimentation area behind the landslide dam in the dam-break area; and the third-level grid is defined as the river channel area of ​​the dam-break area.

[0014] Step S30000: Using the area source data as input data, flood simulation calculations are performed on the first-level grid, the second-level grid, and the third-level grid according to the river dynamics model to obtain flood simulation calculation results. The size of the first-level grid is smaller than the size of the second-level grid, and the size of the second-level grid is smaller than the size of the third-level grid. The flood simulation calculation results of the first-level grid are averaged and aggregated to the second-level grid according to a first ratio. The flood simulation calculation results of the second-level grid are then averaged and aggregated to the third-level grid according to a second ratio.

[0015] Step S40000: Based on the time scale of the dam break parameter model and the river dynamics model, a time scale hierarchical method is used for coupling, and the physical quantities of each node are calculated in stages in sequence. Each stage uses a different time step, and the calculation parameters are changed when entering the next stage, while the terrain data is updated.

[0016] Step S50000: Using time series alignment technology, the initial scale representative flow values ​​output by the dam break parameter model are aligned with the time series, so that the first stage is a second-level dam break flow sequence, the second stage is an hour-level dam break flow sequence, and the third stage is a day-level dam break flow sequence.

[0017] Step S60000: Initial flow coupling is performed on the rivers within the dam breach area. In the initial stage, a constant flow is assigned at the boundary of the dam breach area. The river flow is calculated and it is determined whether the river flow is stable. After the river flow is stable, the boundary flow is changed. Taking the river flow and water depth at the last moment of the initial stage as the initial state, the flow at the boundary of the dam breach area is changed, and the river flow within the dam breach area is calculated. The calculation cycle is consistent with step S40000.

[0018] Step S70000: Calculate the time variation curve of sediment concentration at the breach based on the size change of the dam break parameter model, calculate the sediment content at the breach of the landslide dam based on the process of the change of the dam morphology over time, and update the suspended sediment transport concentration curve based on the change of the sediment content at the breach over time.

[0019] Step S80000: Obtain the topographic elevation matrix after the dam breach. Mark the rigid regions and obtain the coordinate set of the first rigid region, while also obtaining the original terrain elevation matrix. The original terrain elevation matrix The topographic elevation matrix after the dam breach Perform coordinate mapping processing, and mark the corresponding coordinate set of the second rigid region based on the coordinate set of the first rigid region. Zero flow velocity constraint and constant riverbed elevation constraint are applied to the second rigid region;

[0020] Step S90000: Acquire satellite remote sensing data and historical hydrological observations, calculate the sediment input of tributaries, add multiple tributary inflow boundaries based on the sediment input of the tributaries and obtain the corresponding sediment concentration at the breach, set mixed boundary conditions, use a multi-source sediment coupling algorithm, adopt a layered transport model, and distinguish between suspended sediment and bedload based on the suspended sediment transport concentration curve at the tributary inlet. Suspended sediment is solved using the Advance-Diffusion equation, considering the turbulent diffusion coefficient and settling velocity. Bedload is calculated using the Meyer-Peter formula to calculate the sediment transport rate, and the composition of the tributary bed material is dynamically updated through the bed load module.

[0021] Step S100000: Calculate the reservoir capacity-sediment coupling model based on the sediment mass conservation equation, and perform dam failure prediction for the area to be predicted based on the reservoir capacity-sediment coupling model.

[0022] Furthermore, step S30000 in the above-mentioned flood simulation method after a landslide dam breach also includes:

[0023] Step S30100: Align the first-level mesh, the second-level mesh, and the third-level mesh;

[0024] Specifically, the steps for changing the calculation parameters are as follows: obtain the flow velocity, water level, and turbidity at the starting time node of each stage, and use the flow velocity, water level, and turbidity at the starting time node of the next stage as the calculation parameters.

[0025] Furthermore, step S50000 in the above-mentioned flood simulation method after a landslide dam breach also includes:

[0026] Step S50100: Construct the time alignment matrix, calculated as follows:

[0027] (6)

[0028] in, This is the time alignment deviation matrix. The initial scale represents the flow rate value. The representative flow value at the target scale. This is the initial scale time node. The time node is the target scale. When... If the accuracy is less than 5%, the accuracy requirement is met.

[0029] Furthermore, in the above-mentioned flood simulation method after the landslide dam breach, in step S60000, the boundary flow after the river flow stabilizes is changed according to the curve of the breach flow changing over time.

[0030] Furthermore, in the aforementioned method for simulating floods after a landslide dam breach, the criterion for determining whether the river flow is stable in step S60000 is: calculating the relative error of the continuous flow. If the relative error of the continuous flow This indicates that the river flow is stable and the relative error of the continuous flow is small. The formula for calculation is:

[0031] (7)

[0032] in, For outflow volume, For inflow traffic, if This indicates that the flow rate is stable.

[0033] Furthermore, in step S60000 of the above-mentioned flood simulation method after the landslide dam collapse, the river flow and water depth at the last moment of the initial stage are used as the initial state. After changing the flow at the boundary of the collapse area, the river flow in the collapse area is calculated. The calculation period is 20 years after the collapse, that is, the calculation period is consistent with step S40000.

[0034] Furthermore, the formula for calculating the sediment content at the breach point in step S70000 of the above-mentioned flood simulation method after a landslide dam breach is as follows:

[0035] (8)

[0036] in, The sand content at the breach is [value missing]. The dry density of the sediment. Porosity This represents the volume loss per unit time. For the breach flow rate, The unit of time is the change time.

[0037] Furthermore, the calculation formula for the reservoir capacity-sediment coupling model in step S100000 of the above-mentioned flood simulation method after the landslide dam breach is as follows:

[0038] (9)

[0039] in, This represents the change in sediment volume per unit time. The inflow sediment content, The sediment content of the outflow. This refers to the amount of sediment deposited in the subsoil.

[0040] Next, an empirical formula was used to calculate the sediment storage capacity model for the river section. The empirical formula is as follows:

[0041] (10)

[0042] in, The reservoir capacity and sediment volume at different times. This represents the initial sediment deposition in the river section. It is an exponent symbol. The scouring coefficient is... For time.

[0043] According to another aspect of the present invention, the present invention also provides a flood simulation device after a landslide dam breach, comprising:

[0044] Module S10000: Used to obtain the elevation of the reservoir water level, the elevation of the breach bottom, the inflow rate into the reservoir, the initial breach width, and the erosion rate of the landslide dam. Based on the breach parameter model, the breach flow evolution curve, the suspended sediment transport concentration curve, and the reservoir water level decay curve are calculated. Based on a dynamic constraint cross-scale data bridging mechanism, a spatiotemporal convolution kernel mapping algorithm is used to convert the breach flow evolution curve, the suspended sediment transport concentration spectrum, and the reservoir water level decay curve from the point source data into the area source data.

[0045] Module S20000: Used for the multi-level grid system based on the inverse AMR concept, dividing the dam-break area into a first-level grid, a second-level grid, and a third-level grid according to the grid size. The first-level grid is defined as the dam body area of ​​the landslide dam in the dam-break area; the second-level grid is defined as the sedimentation area behind the landslide dam in the dam-break area; and the third-level grid is defined as the river channel area of ​​the dam-break area.

[0046] Module S30000: Used to take the area source data as input data, and according to the river dynamics model, perform flood simulation calculations on the first-level grid, the second-level grid, and the third-level grid respectively to obtain the flood simulation calculation results, wherein the size of the first-level grid is smaller than the size of the second-level grid, the size of the second-level grid is smaller than the size of the third-level grid, the flood simulation calculation results of the first-level grid are averaged and aggregated to the second-level grid according to a first ratio, and the flood simulation calculation results of the second-level grid are further averaged and aggregated to the third-level grid according to a second ratio;

[0047] Module S40000: Used to couple the dam break parameter model and the river dynamics model using a time-scale hierarchical method, calculate the physical quantities of each node in stages, with different time steps for each stage, and change the calculation parameters when entering the next stage, while updating the terrain data.

[0048] Module S50000: Used to perform time series alignment on the initial scale representative flow value output by the dam break parameter model using the time series alignment technology, so that the first stage is a second-level dam break flow sequence, the second stage is an hour-level dam break flow sequence, and the third stage is a day-level dam break flow sequence.

[0049] Module S60000: Used to perform initial flow coupling on the river within the dam breach area. In the initial stage, a constant flow is assigned at the boundary of the dam breach area. The river flow is calculated and it is determined whether the river flow is stable. After the river flow is stable, the boundary flow is changed. The river flow and water depth at the last moment of the initial stage are used as the initial state. After changing the flow at the boundary of the dam breach area, the river flow of the river within the dam breach area is calculated. The calculation cycle is consistent with step S40000.

[0050] Module S70000: Used to calculate the time variation curve of the sediment concentration at the breach based on the size change of the dam break parameter model, calculate the sediment content at the breach of the landslide dam based on the process of the dam morphology changing over time, and update the suspended sediment transport concentration curve based on the change of the sediment content at the breach over time.

[0051] Module S80000: Obtain the terrain elevation matrix after a dam breach. Mark the rigid regions and obtain the coordinate set of the first rigid region, while also obtaining the original terrain elevation matrix. The original terrain elevation matrix The topographic elevation matrix after the dam breach Perform coordinate mapping processing, and mark the corresponding coordinate set of the second rigid region based on the coordinate set of the first rigid region. Zero flow velocity constraint and constant riverbed elevation constraint are applied to the second rigid region;

[0052] Module S90000: Used to acquire satellite remote sensing data and historical hydrological observations, calculate the sediment input of tributaries, add multiple tributary inflow boundaries based on the sediment input of tributaries and obtain the corresponding sediment concentration at the breach, set the mixed boundary conditions, use the multi-source sediment coupling algorithm, adopt the layered transport model, and distinguish between suspended sediment and bedload based on the suspended sediment transport concentration curve at the tributary inlet. The suspended sediment is solved by the Advance-Diffusion equation, considering the turbulent diffusion coefficient and settling velocity. The bedload transport rate is calculated using the Meyer-Peter formula. The composition of the tributary bed material is dynamically updated through the bed load module.

[0053] Module S100000: Used to calculate the reservoir capacity-sediment coupling model based on the sediment mass conservation equation, and to perform dam failure prediction in the area to be predicted based on the reservoir capacity-sediment coupling model.

[0054] The above-mentioned technical solution of the present invention has the following beneficial technical effects: it seamlessly connects the transient process (minute-level) of landslide dam failure with the long-term sediment transport (annual-level), enabling coupled calculation of small-scale landslide dam failure and large-scale river geomorphological evolution, thereby extrapolating the river geomorphology several years after the dam failure. Furthermore, the time series alignment technology effectively ensures the accuracy of cross-scale data transmission, making up for the limitations of traditional calculation models in simulating short-term breaches and short-term river scour. At the same time, it can also simultaneously simulate the interactive processes of breach dynamic expansion, sediment transport, and riverbed evolution. Attached Figure Description

[0055] Figure 1 This is a flowchart of a method according to an embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram of the evolution of landforms at different scales after the collapse of a landslide dam according to an embodiment of the present invention.

[0057] Figure 3 This is a schematic diagram of the change curve of the breach flow rate over time according to an embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram illustrating the change in the morphology of a landslide dam breach over time according to an embodiment of the present invention.

[0059] Figure 5 This is a schematic diagram of the suspended sediment transport concentration curve according to an embodiment of the present invention;

[0060] Figure 6 This is a schematic diagram of the grid division of a river dynamics model according to an embodiment of the present invention;

[0061] Figure 7 This refers to the changes in sediment deposition at the bottom of river channels at different time scales according to embodiments of the present invention.

[0062] Figure 8 This is a structural block diagram according to an embodiment of the present invention. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0064] refer to Figure 1 The embodiments of the present invention will be described in detail below. The flood simulation method after the collapse of a landslide dam shown in this embodiment includes the following steps:

[0065] Step S10000: Obtain the elevation of the reservoir water level, the elevation of the breach bottom, the inflow rate into the reservoir, the initial breach width, and the erosion rate of the landslide dam. Based on the dam break parameter model, calculate the breach flow evolution curve, suspended sediment transport concentration curve, and reservoir water level decay curve. Based on the dynamic constraint cross-scale data bridging mechanism, use the spatiotemporal convolution kernel mapping algorithm to transform the breach flow evolution curve, suspended sediment transport concentration spectrum, and reservoir water level decay curve from point source data into area source data.

[0066] Step S20000: Based on the concept of inverse AMR (Adaptive Mesh Refinement), a multi-level grid system is used to divide the dam-break area into first-level, second-level, and third-level grids according to the grid size. The first-level grid is defined as the dam body area of ​​the landslide dam in the dam-break area; the second-level grid is defined as the sedimentary area behind the landslide dam in the dam-break area; and the third-level grid is defined as the river channel area of ​​the dam-break area.

[0067] Step S30000: Using area source data as input data, flood simulation calculations are performed on the first-level grid, the second-level grid, and the third-level grid according to the river dynamics model to obtain flood simulation calculation results. The size of the first-level grid is smaller than that of the second-level grid, and the size of the second-level grid is smaller than that of the third-level grid. The flood simulation calculation results of the first-level grid are averaged and aggregated to the second-level grid according to the first ratio. The flood simulation calculation results of the second-level grid are then averaged and aggregated to the third-level grid according to the second ratio.

[0068] In step S30000 of this embodiment, the size of the first-level grid is 0.50m×0.50m, the size of the second-level grid is 2.5m×2.5m, the size of the third-level grid is 20m×20m, the first ratio is 5, and the second ratio is 8.

[0069] Step S30000 also includes:

[0070] Step S30100: Align the first-level grid, the second-level grid, and the third-level grid.

[0071] Step S40000: Based on the time scale of the dam break parameter model and the river dynamics model, a time scale hierarchical method is used for coupling. The physical quantities of each node are calculated in stages, with different time steps for each stage. The calculation parameters are changed when entering the next stage, and the terrain data is updated at the same time.

[0072] Specifically, the steps for changing the calculation parameters are as follows: obtain the flow velocity, water level, and turbidity at the starting time node of each stage, and use the flow velocity, water level, and turbidity at the starting time node of the next stage as the calculation parameters.

[0073] In step S40000 of this embodiment, the calculation of physical quantities (including flow velocity, water level, turbidity, etc.) of each node is divided into three stages: the first stage, the second stage, and the third stage. The time scale of the dam break parameter model is the day scale, while the time scale of the river dynamics model is the year scale. After adopting the time scale classification method, the time step Δt = 1 second in the first stage calculation, the time step Δt = 1 hour in the second stage calculation, and the time step Δt = 1 day in the third stage calculation.

[0074] If we calculate the evolution of river sediment 20 years after a dam failure, the first stage lasts for one day, with a time step in the order of seconds (Δt = 1 second). The calculation ends after 86,400 seconds (1 day). After the first stage, the second stage begins, lasting for one year. The calculation parameters are changed, and the time step is changed to the order of hours (Δt = 1 hour). The calculation ends after 8,760 hours (364 days). After the second stage, the third stage begins, lasting for 19 years, with a time step in the order of days (Δt = 1 day). The calculation ends after 6,935 days (19 years).

[0075] Step S50000: Using time series alignment technology, the initial scale representative flow values ​​output by the dam break parameter model are aligned over time, so that the first stage is a second-level dam break flow series, the second stage is an hour-level dam break flow series, and the third stage is a day-level dam break flow series; Step S50000 also includes:

[0076] Step S50100: Construct the time alignment matrix, calculated as follows:

[0077] (11)

[0078] in, This is the time alignment deviation matrix. The initial scale represents the flow rate value. The representative flow value at the target scale. This is the initial scale time node. The time node is the target scale. When... If the accuracy is less than 5%, the accuracy requirement is met.

[0079] Step S60000: Perform initial flow coupling on the rivers within the dam breach area. In the initial stage, a constant flow is assigned at the boundary of the dam breach area. Calculate the river flow and determine whether the river flow is stable. After the river flow stabilizes, change the boundary flow. Using the river flow and water depth at the last moment of the initial stage as the initial state, change the flow at the boundary of the dam breach area and calculate the river flow within the dam breach area. The calculation cycle is consistent with step S40000.

[0080] Specifically, in step S60000, the boundary flow after the river flow stabilizes is changed based on the curve of the breach flow changing over time.

[0081] Specifically, the criterion for determining whether the river flow is stable in step S60000 is: calculating the relative error of the continuous flow. If the relative error of the continuous flow This indicates that the river flow is stable and the relative error of the continuous flow is small. The formula for calculation is:

[0082] (12)

[0083] in, For outflow volume, For inflow traffic, if This indicates that the flow rate is stable.

[0084] In step S60000 of this embodiment, the river flow and water depth at the last moment of the initial stage are taken as the initial state. After changing the flow at the boundary of the dam breach area, the river flow in the dam breach area is calculated. The calculation period is 20 years after the dam breach, that is, the calculation period is consistent with step S40000.

[0085] Step S70000: Calculate the time-varying curve of sediment concentration at the breach based on the dimensional changes of the dam break parameter model. Calculate the sediment concentration at the breach point based on the time-varying process of the dam morphology. Simultaneously, update the suspended sediment transport concentration curve based on the time-varying sediment concentration at the breach point. The formula for calculating the sediment concentration at the breach point is:

[0086] (13)

[0087] in, This refers to the sand content at the breach. The dry density of the sediment. Porosity This represents the volume loss per unit time. For the breach flow rate, The unit of time is the change time.

[0088] Step S80000: Obtain the topographic elevation matrix after the dam breach. Mark the rigid regions and obtain the coordinate set of the first rigid region, while also obtaining the original terrain elevation matrix. The original terrain elevation matrix Topographic elevation matrix after dam breach Perform coordinate mapping processing, and label the corresponding coordinate set of the second rigid region based on the coordinate set of the first rigid region. Zero velocity constraint and constant riverbed elevation constraint are applied to the second rigid region.

[0089] In step S80000 of this embodiment, the rigid area is the upper part of the bank slope, such as the mountain, while the non-rigid area is the bottom of the river channel, which is the eroded terrain.

[0090] Step S90000: Acquire satellite remote sensing data and historical hydrological observations, calculate the sediment input of tributaries, add multiple tributary inflow boundaries based on the sediment input of tributaries and obtain the corresponding breach sediment concentration, set mixed boundary conditions, use a multi-source sediment coupling algorithm, adopt a layered transport model, distinguish between suspended sediment and bedload based on the suspended sediment transport concentration curve at the tributary inlet, wherein suspended sediment is solved by the Advance-Diffusion equation, considering the turbulent diffusion coefficient and settling velocity, and bedload is calculated using the Meyer-Peter formula to calculate the sediment transport rate, and dynamically update the tributary bed material composition through the bed load module.

[0091] In step S90000 of this embodiment, the area on both sides of the river channel is set as a fourth-level grid. The size of the fourth-level grid is 70m×70m. Since this area is not involved in the calculation, using a larger grid can save computing resources.

[0092] Step S100000: Calculate the reservoir capacity-sediment coupling model based on the sediment mass conservation equation, and then use this model to predict dam failure in the area to be predicted. The calculation formula for the reservoir capacity-sediment coupling model is as follows:

[0093] (14)

[0094] in, This represents the change in sediment volume per unit time. The inflow sediment content, The sediment content of the outflow. This refers to the amount of sediment deposited in the subsoil.

[0095] Next, an empirical formula was used to calculate the sediment storage capacity model for the river section. The empirical formula is as follows:

[0096] (15)

[0097] in, The reservoir capacity and sediment volume at different times. This represents the initial sediment deposition in the river section. It is an exponent symbol. The scouring coefficient is... For time.

[0098] Specifically, in step S100000, a calculation model is first established based on the water level, flow rate, and sediment content at different locations along the entire river channel. Then, based on the simulation results of the calculation model, the inflow sediment concentration, outflow sediment concentration, inflow flow rate, outflow flow rate, and bed sedimentation are calculated. A reservoir capacity-sediment coupling model is then established based on these parameters. Finally, the flood following the dam failure is simulated using both the reservoir capacity-sediment coupling model and the river section sediment-storage capacity model.

[0099] The following detailed explanation uses a specific calculation example, taking the 2000 Yigong landslide dam breach as an example. The dam was 2500m long, 2500m wide, and had an average thickness of 60m. The downstream river channel's scouring and sedimentation calculation range was 270km. Based on a coupled model, the evolution of landforms after sediment transport at different time scales (1 day, 12 months, 20 years) following the dam breach was calculated. For example... Figure 2 As shown.

[0100] Based on a dynamic constraint-based cross-scale data bridging mechanism, a multi-physics time-series dataset generated from a dam-break parameter model is used to generate the breach flow evolution curve. Suspended sediment transport concentration spectrum Reservoir water level decay curve These are high-dynamic point source data. Using a spatiotemporal convolution kernel mapping algorithm, centimeter-level dam-break point source terms are transformed into surface source data for the river dynamics model, thus assigning the first-level grid driving field to the upstream boundary layer of the river dynamics model.

[0101] First, an inversion was performed based on measured flow data. The failure process of the Yigong landslide dam was simulated using a dam-break parameter model, and the curve of the breach flow versus time was calculated, as shown below. Figure 3 As shown.

[0102] Next, based on the dam break parameter model, the change process of the dam breach morphology over time was calculated, such as... Figure 4 As shown, the volume change of the landslide dam per unit time was calculated based on the breach morphology, thus obtaining the suspended sediment transport concentration curve, as shown. Figure 5 As shown.

[0103] Then, the sediment content of the flood at the breach of the dam was calculated based on the time variation curve of suspended sediment transport.

[0104] A multi-level grid system based on the inverse AMR concept was used to divide the dam-break area into four levels: Level 1 (L0), Level 2 (L1), Level 3 (L2), and Level 4. The Level 1 grid was defined as the dam body of the landslide dam within the dam-break area; the Level 2 grid as the sedimentary zone behind the dam body; the Level 3 grid as the river channel; and the Level 4 grid as the area flanked by mountains. The dimensions of the Level 1 grid were 0.50m × 0.50m, the Level 2 grid was 2.5m × 2.5m, the Level 3 grid was 20m × 20m, and the Level 4 grid was 80m × 80m. The Level 1 grid served as the fine-grained layer for detailed dam-break morphology simulation; the Level 2 grid served as a transitional layer, acting as a data aggregation and transfer interface; the Level 3 grid served as the macroscopic layer for river dynamics flood simulation; and the Level 4 grid did not participate in the actual calculations, thus saving computational resources. The calculation results of the first-level grid are aggregated to the second-level grid at a ratio of 5:1, and then the calculation results of the second-level grid are aggregated to the third-level grid at a ratio of 8:1. That is, 40 grid cells of the first-level grid drive 1 grid cell of the third-level grid to simulate river dynamics floods.

[0105] Next, the side slopes are meshed. Unstructured meshing technology and adaptive refinement algorithms are used to refine the mesh for special terrain features such as river valleys and tributaries. A third-level mesh (20m × 20m) is used, while a fourth-level mesh (80m × 80m) is used on the side slopes. This improves computational efficiency and ensures computational accuracy. Figure 6 As shown.

[0106] Next, the initial flow coupling of the river begins. In the initial stage, a constant boundary flow is assigned. The calculation ends after the water flows into the river channel and the flow stabilizes. The calculation continues until the relative error of the flow is reached, at which point the river flow tends to stabilize. Then, using the river flow and water depth at the last moment as the initial values, the river flow in the dam failure area is calculated 20 years after the dam failure.

[0107] The calculation process is divided into three stages: Stage 1, Stage 2, and Stage 3. Stage 1 has a calculation period of one day, with a time step in seconds, and completes after 86,400 seconds (one day), yielding the calculated terrain file. Stage 2 has a calculation period of one year, with a time step in hours, and after changing the calculation parameters, completes after 8,760 hours (364 days). Stage 3 has a calculation period of 19 years, with a time step in days, and after changing the calculation parameters, completes after 6,935 days (19 years).

[0108] When performing scale transfer, time series alignment technology is used to obtain the second-level breach flow rate from the breach flow rate change curve output from the dam break parameter model, and align it with the hour-level and day-level breach flow rates to ensure transfer accuracy.

[0109] After the short-term flood outburst calculation is completed, the representative flow value of the initial scale for the last hour is extracted; at the same time, the representative flow value of the target scale for the first hour of the medium-term calculation is extracted, and the flood peak difference at different locations in the upstream, midstream and downstream is compared. For example, in the upstream river section, if it is <5%, it means that the accuracy is met and the calculation can continue; otherwise, the parameters are adjusted until the accuracy meets the standard.

[0110] Next, the sediment inflow from multiple tributaries was processed. By combining satellite remote sensing data and historical hydrological observations, the sediment input of the tributaries was calculated. Based on the sediment input of the tributaries, multiple tributary inflow boundaries were added and the corresponding sediment concentration at the breach was obtained.

[0111] Obtain the topographic elevation matrix after the dam breach, mark the rigid regions and obtain the coordinate set of the first rigid region, and at the same time obtain the original topographic elevation matrix. Perform coordinate mapping processing between the original topographic elevation matrix and the topographic elevation matrix after the dam breach. Mark the coordinate set of the corresponding second rigid region according to the coordinate set of the first rigid region, and apply zero flow velocity constraint and riverbed elevation invariance constraint to the second rigid region.

[0112] Next, based on satellite remote sensing data and historical hydrological observations, the sediment input of the tributary is calculated, and the corresponding sediment concentration at the breach is obtained. Finally, the composition of the tributary bed material is dynamically updated through the bed load module.

[0113] Based on the sediment mass conservation equation, a reservoir capacity-sediment coupling model is calculated. This model can then be used to predict the area to be predicted. The calculation results are as follows: Figure 7 As shown.

[0114] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method of flood simulation after dam break of a barrier dam, characterized by, The method comprises the following steps: Step S10000: acquiring the elevation of the reservoir water level of the dam, the elevation of the breach bottom, the flow into the reservoir, the initial breach width, and the erosion rate, and calculating the breach flow evolution curve, the suspended sediment concentration curve, and the reservoir water level decay curve according to a dam breach parameter model, and converting the point source data into surface source data; Step S20000: dividing the dam breach area into a first-level grid, a second-level grid, and a third-level grid according to the grid size; Step S30000: taking the surface source data as input data, performing flood simulation calculation on the first-level grid, the second-level grid, and the third-level grid according to a river dynamics model to obtain a flood simulation calculation result, and continuing to average the flood simulation calculation result of the second-level grid to the third-level grid according to a second ratio; Step S40000: coupling by using a time scale hierarchical method according to the time scale of the dam breach parameter model and the river dynamics model, calculating the physical quantity of each node in stages, using different time steps in each stage, changing the calculation parameters when entering the next stage, and updating the terrain data; Step S50000: using a time series alignment technology to perform time series alignment on the initial scale representative flow value output by the dam breach parameter model; Step S60000: coupling the initial flow of the river in the dam breach area, assigning a constant flow at the boundary of the dam breach area in the initial stage, calculating the river flow and judging whether the river flow is stable, and changing the boundary flow after the river flow is stable; Step S70000: calculating the time variation curve of the breach sediment concentration according to the size variation of the dam breach parameter model; Step S80000: Obtain a post-failure topographic elevation matrix , mark a rigid region and obtain a coordinate set of a first rigid region, while obtaining an original topographic elevation matrix , mark a rigid region and obtain a coordinate set of a first rigid region, while obtaining an original topographic elevation matrix , mark a rigid region and obtain a coordinate set of a first rigid region, while obtaining an original topographic elevation matrix , mark a rigid region and obtain a coordinate set of a first rigid region, while obtaining an original topographic elevation matrix , mark a rigid region and obtain a coordinate set of a first rigid region, while obtaining an original topographic elevation matrix Step S90000: acquiring satellite remote sensing data and historical hydrological observation, calculating the sediment input of the tributary, adding a plurality of tributary inflow boundaries according to the sediment input of the tributary and acquiring the corresponding sediment concentration at the breach ; Step S100000: calculating a reservoir capacity-sediment coupling model according to the sediment mass conservation equation, and predicting the dam breach of the to-be-predicted area according to the reservoir capacity-sediment coupling model.

2. The dam breach flood simulation method according to claim 1, characterized in that: the cross-scale data bridging mechanism based on dynamic constraints in the step S10000 converts the breach flow evolution curve, the suspended sediment concentration curve, and the reservoir water level decay curve from point source data to surface source data by using a spatiotemporal convolution kernel mapping algorithm; the multiple hierarchical grid system based on the inverse AMR idea divides the dam breach area into grids in the step S20000, wherein the first-level grid division standard is the dam body area of the dam in the dam breach area, the second-level grid division standard is the deposition area behind the dam body of the dam in the dam breach area, and the third-level grid division standard is the river area in the dam breach area; the size of the first-level grid is smaller than the size of the second-level grid, and the size of the second-level grid is smaller than the size of the third-level grid in the step S30000, and the flood simulation calculation result of the first-level grid is averaged to the second-level grid according to a first ratio, The step S40000 calculates the physical quantity of each node, which is divided into a first stage, a second stage and a third stage, the first stage is a second-level breach flow sequence, the second stage is a hour-level breach flow sequence, and the third stage is a day-level breach flow sequence; In the step S60000, the river flow and water depth at the last time of the initial stage are used as the initial state, the flow at the boundary of the dam-break area is changed, the river flow in the dam-break area is calculated, and the calculation period is consistent with the step S40000. In the step S70000, the sediment concentration at the breach of the dam is calculated according to the change of the dam shape over time, and the suspended sediment concentration curve is updated according to the change of the sediment concentration at the breach over time. In the step S90000, a mixed boundary condition is also set, a multi-source sediment coupling algorithm is used, a layered transport model is adopted, the suspended sediment and bed load are distinguished according to the suspended sediment concentration curve at the inlet of the branch, the suspended sediment is solved by an Advection-Diffusion equation, the turbulent diffusion coefficient and the settling velocity are considered, the bed load is calculated by using a Meyer-Peter formula, and the bed material composition of the branch is dynamically updated by a bottom load module.

3. The dam-break flood simulation method according to claim 2, wherein the step S30000 further comprises: The step S30100 comprises aligning the first-level grid, the second-level grid and the third-level grid. The specific step of changing the calculation parameters comprises obtaining the flow rate, water level and turbidity at the starting time node of each stage, and taking the flow rate, water level and turbidity at the starting time node of the next stage as the calculation parameters when entering the next stage.

4. The dam-break flood simulation method according to claim 3, wherein the step S50000 further comprises: The step S50100 comprises constructing a time alignment matrix, and the calculation formula is:

5. The dam-break flood simulation method according to claim 4, wherein in the step S60000, the boundary flow after the river flow is stabilized is changed according to the change curve of the breach flow over time.

6. The dam-break flood simulation method according to claim 4, wherein in the step S60000, the river flow in the dam-break area is calculated after the flow at the boundary of the dam-break area is changed, and the calculation period is consistent with the step S40000. （1） wherein, is a time alignment matrix, is a representative flow value of the initial scale, is a representative flow value of the target scale, is a time node of the initial scale, is a time node of the target scale, when the accuracy meets the requirements when < 5%.

7. The dam-break flood simulation method according to claim 4, wherein in the step S60000, the river flow in the dam-break area is calculated after the flow at the boundary of the dam-break area is changed, and the calculation period is consistent with the step S40000.

8. The dam-break flood simulation method according to claim 4, wherein in the step S70000, the calculation formula of the sediment concentration at the breach is:

9. The dam-break flood simulation method according to claim 4, wherein the calculation formula of the reservoir capacity-sediment coupling model in the step S100000 is: The judgment criterion of whether the river flow is stable in the step S60000 is that the relative error of the continuous flow is calculated If the relative error of the continuous flow is , it represents that the river flow is stable, and the calculation formula of the relative error of the continuous flow is ​ （2） where is the outflow flux, is the inflow flux, if the flag flux is stable. ​ ​ ​ ​ （3） wherein, is the sediment concentration at the breach, is the dry density of the sediment, is the porosity, is the volume loss per unit time, is the breach flow rate, is the unit change time. ​ ​ （4） wherein, is the change in sediment per unit time, is the incoming sediment concentration, is the outgoing sediment concentration, is the bed accretion, is the outgoing flow rate, is the incoming flow rate; Then the sediment storage capacity model of the reach is calculated by using the empirical formula, which is as follows: （5） wherein, is the sediment volume of the river reach at different time, is the initial sediment deposition volume of the river reach, is the exponential symbol, is the scour coefficient, is the time.

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