A method for analyzing damming and submerging of a bridge by a mountain flood

Abstract

The application discloses a mountain torrent disaster bridge waterlogging analysis method, extracts the target river center line according to the digital elevation model data of the river area to be analyzed and the target bridge position. According to the first elevation of a plurality of preset river section sample points, the river gradient, the waterlogging length and the terrain complexity index of the target river center line are determined. According to the river gradient and the waterlogging length, the gradient attenuation model of the waterlogging curve and the terrain complexity index are constructed, and the second elevations of three adaptive river section sample points of each adaptive river section of the target river center line are obtained. According to the digital elevation model data, a plurality of second elevations and a preset comprehensive weight function, the third elevations of each river section target point are determined by a terrain factor weighted inverse distance weighted interpolation method. According to the preset segmentation straight line of the target bridge, the preset reference directed distance and a plurality of river section target points, the submerged range is determined. According to a plurality of third elevations and the submerged range, the submerged analysis result is obtained.

Description

Technical Field

[0001] This invention relates to the field of flash flood disaster analysis technology, and in particular to a method for analyzing bridge flooding caused by flash floods. Background Technology

[0002] In flash floods, the contraction of the bridge's cross-sectional area can cause backwater in the upstream river channel, increasing the risk of flooding. Therefore, the analysis, early warning, and forecasting of bridge flooding due to backwater in flash floods are of paramount importance.

[0003] In existing technologies, traditional methods for assessing bridge flooding caused by flash floods first involve manually interpreting topographic maps to extract the river centerline. Next, flood-prone cross-sections are sampled at fixed intervals. Finally, based on distance weights, an interpolation algorithm is used to determine the inundation range, thereby obtaining the analysis results for bridge flooding caused by flash floods.

[0004] However, using existing technologies, it is difficult to accurately extract the centerline of the river channel when dealing with complex terrain, and the method does not fully consider the variations in terrain complexity, resulting in insufficient sampling data. Furthermore, this method ignores the influence of factors such as terrain slope, curvature, and surface roughness on water flow diffusion, thereby reducing the accuracy and efficiency of bridge flooding analysis in flash flood disasters. Summary of the Invention

[0005] The purpose of this invention is to provide a method for analyzing bridge flooding caused by flash floods. This method addresses the shortcomings of existing techniques, such as difficulty in accurately extracting the centerline of rivers in complex terrain and insufficient consideration of variations in terrain complexity, leading to inadequate sampling data. Furthermore, this method neglects the influence of factors like terrain slope, curvature, and surface roughness on water flow diffusion, thereby reducing the accuracy and efficiency of bridge flooding analysis in flash flood disasters.

[0006] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a method for analyzing bridge flooding caused by flash floods, comprising:

[0007] Based on the digital elevation model data of the river channel area to be analyzed and the location of the target bridge, the centerline of the target river channel is extracted. The river channel area to be analyzed includes multiple target points of the river channel cross section.

[0008] Based on the first elevation of multiple preset river cross-section sample points corresponding to the target river centerline, determine the river gradient, backwater length, and terrain complexity index corresponding to the target river centerline.

[0009] Based on the riverbed gradient and the backwater length, a backwater curve gradient decay model is constructed.

[0010] Based on the backwater curve gradient decay model and the terrain complexity index, the second elevation of the three adaptive river section sample points corresponding to each adaptive river section corresponding to the target river centerline is obtained.

[0011] Based on digital elevation model data, multiple second elevations, and a preset comprehensive weight function, the third elevation of each target point in a river section is determined using a terrain factor weighted inverse distance weight interpolation method. The preset comprehensive weight function is determined based on adaptive river section sample points, the distance weight of the target point in the river section, and the terrain factor weight.

[0012] The inundation range is determined based on the preset dividing line corresponding to the target bridge, the preset reference directional distance, and multiple target points of the river section.

[0013] The inundation analysis results were obtained based on multiple third elevations and the inundation range.

[0014] In one embodiment, extracting the centerline of the target river channel based on the digital elevation model data of the river area to be analyzed and the location of the target bridge includes:

[0015] Based on the digital elevation model data, a river network is obtained according to the flow direction and confluence characteristics of multiple rivers within the river area to be analyzed;

[0016] In the river network, identify the target river channel closest to the target bridge location, and extract the initial river channel centerline of the target river channel using a centerline transformation algorithm;

[0017] The initial river channel centerline is geometrically smoothed to obtain the target river channel centerline.

[0018] In one embodiment, determining the river gradient, backwater length, and terrain complexity index corresponding to the target river centerline based on the first elevation of multiple preset river cross-section sample points corresponding to the target river centerline includes:

[0019] The river gradient is determined based on the first elevation of multiple preset river cross-section sample points and the preset river gradient calculation formula.

[0020] The water damming length is determined based on the river gradient and the preset formula for calculating the water damming length.

[0021] Based on the first elevation of the multiple preset river cross-section sample points, the river longitudinal slope change rate, river plane curvature, and surface roughness are obtained.

[0022] The terrain complexity index is determined by weighted summation of the river channel longitudinal slope variation rate, river channel planar curvature, and surface roughness.

[0023] In one embodiment, determining the river gradient based on the first elevation of multiple preset river cross-section sample points and a preset river gradient calculation formula includes:

[0024] Based on the first elevation of multiple preset river section sample points and the formula for calculating the local gradient of the river section, the local gradient of the river section at each preset river section sample point is calculated.

[0025] The river gradient is determined based on the local gradients of multiple river sections and a preset river gradient calculation formula.

[0026] In one embodiment, the formula for calculating the local gradient of the river section can be defined by the following expression:

[0027]

[0028] in, Indicates the first i The local gradient of the river section corresponding to each preset river cross-section sample point Indicates the first i The length of the river segment corresponding to each preset river cross-section sample point. Indicates the first i The first elevation corresponding to each preset river cross-section sample point Indicates the first i+ The first elevation corresponding to a preset river cross-section sample point;

[0029] The preset river gradient calculation formula can be defined by the following expression:

[0030]

[0031] in, This indicates the gradient of the river channel. n This indicates the total number of sample points for multiple preset river cross-sections.

[0032] The formula for calculating the preset backwater length can be defined by the following expression:

[0033]

[0034] in, L Indicates the length of the dammed water. h Indicates the height of the target bridge. λ This represents the correction factor for the backwater length.

[0035] In one embodiment, the backwater curve gradient decay model can be defined by the following expression:

[0036]

[0037] in, This represents the gradient decay of the backwater curve at each preset river cross-section sample point. This indicates the distance between the sample point of the preset river section and the target bridge location.

[0038] In one embodiment, obtaining the second elevation of three adaptive river cross-section sample points corresponding to each adaptive river cross-section corresponding to the target river centerline based on the backwater curve gradient decay model and the terrain complexity index includes:

[0039] Based on the backwater curve gradient decay model, terrain complexity index, and preset spacing calculation formula, the spacing between any two adjacent adaptive river sections in multiple adaptive river sections is obtained.

[0040] Based on multiple intervals, the initial adaptive river channel cross-section sample points are obtained for each adaptive river channel cross-section through a reverse indexing mechanism.

[0041] Based on the initial adaptive river section sample points and the adjacent initial adaptive river section sample points, determine the three adaptive river section sample points corresponding to each adaptive river section.

[0042] Calculate the second elevation corresponding to the three adaptive river cross-section sample points according to the preset elevation calculation formula;

[0043] The formula for calculating the preset spacing can be defined by the following expression:

[0044]

[0045] in, This represents the distance between any two adjacent adaptive channel sections. Indicates the minimum cross-sectional spacing. Indicates the maximum cross-sectional spacing. This represents the maximum gradient decay value of the backwater curve. Indicates the terrain complexity index. This represents the gradient decay of the backwater curve at each preset river cross-section sample point;

[0046] The preset elevation calculation formula can be defined by the following expression:

[0047]

[0048] in, This represents the distance from the target bridge location to the initial adaptive river channel cross-section sample point corresponding to each adaptive river channel cross-section. Indicates the bridge deck elevation of the target bridge. This represents the second elevation of the three adaptive river channel sample points corresponding to each adaptive river channel section.

[0049] In one embodiment, before determining the third elevation of each river cross-section target point using a terrain factor weighted inverse distance weighting interpolation method based on digital elevation model data, multiple second elevations, and a preset comprehensive weighting function, the method further includes:

[0050] Obtain initial digital elevation model data, and perform deep pit preprocessing on the initial digital elevation model data to obtain the digital elevation model data;

[0051] Based on the digital elevation model data, terrain factor raster processing is performed to obtain the first terrain factor parameters corresponding to multiple river cross-section target points.

[0052] The terrain factor weights are determined based on the first terrain factor parameters corresponding to each target point of the river section and the second terrain factor parameters corresponding to multiple adaptive river section sample points.

[0053] The distance weights are determined based on the reciprocals of the distances between each target point of the river cross section and multiple adaptive river cross section sample points.

[0054] The distance weight and the terrain factor weight are multiplied to determine the preset comprehensive weight function.

[0055] In one embodiment, determining the third elevation of each target point at a river cross-section based on digital elevation model data, multiple second elevations, and a preset comprehensive weighting function using a terrain factor-weighted inverse distance weighting interpolation method includes:

[0056] The digital elevation model data is downsampled.

[0057] For the digital elevation model data after downsampling, the initial elevations of multiple river cross-section target points are determined by using a terrain factor weighted inverse distance weight interpolation method based on multiple second elevations and a preset comprehensive weight function.

[0058] Based on the digital elevation model data, the third elevation of each river cross-section target point is determined using the terrain factor weighted inverse distance weight interpolation method, according to the initial elevation of the multiple river cross-section target points, the multiple second elevations, and the preset comprehensive weight function.

[0059] In one embodiment, determining the inundation range based on the preset dividing line corresponding to the target bridge, the preset reference directional distance, and multiple target points of the river cross-section includes:

[0060] Based on the set of coordinates of the target bridge, construct the preset dividing line;

[0061] Calculate the preset reference directed distance between the initial adaptive river cross section sample point corresponding to the second adaptive river cross section and the preset dividing line;

[0062] Calculate the directed distance between each target point in the river channel cross-section and the preset dividing line;

[0063] The flooding range is determined based on the preset reference directional distance and multiple directional distances.

[0064] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art:

[0065] This invention provides a method for analyzing bridge flooding caused by flash floods. The method extracts the target river centerline based on digital elevation model data of the river region to be analyzed and the location of the target bridge. The river region includes multiple target points at river cross-sections. Based on the first elevation of multiple preset river cross-section sample points corresponding to the target river centerline, the river gradient, flood length, and terrain complexity index corresponding to the target river centerline are determined. A flood curve gradient decay model is constructed based on the river gradient and flood length. Based on the flood curve gradient decay model and the terrain complexity index, the second elevation of three adaptive river cross-section sample points corresponding to each adaptive river cross-section corresponding to the target river centerline is obtained. Based on the digital elevation model data, multiple second elevations, and a preset comprehensive weight function, the third elevation of each target point at the river cross-section is determined using a terrain factor weighted inverse distance weight interpolation method. The preset comprehensive weight function is determined based on the distance weights of the adaptive river cross-section sample points and the target points at the river cross-sections, as well as the terrain factor weights. The inundation range is determined based on the preset dividing lines corresponding to the target bridge, the preset directional reference distances, and multiple target points at river cross-sections. Inundation analysis results are obtained based on multiple third elevations and the inundation range. This eliminates the need for manual interpretation of topographic maps to extract the river centerline, improving the accuracy of centerline extraction. In complex terrain conditions, it considers terrain complexity, avoids insufficient sampling data, and improves the accuracy and efficiency of bridge flooding analysis during flash floods. Attached Figure Description

[0066] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0067] Figure 1 A flowchart illustrating a method for analyzing bridge flooding caused by flash floods, provided in an embodiment of the present invention.

[0068] Figure 2This is a schematic diagram of extracting the center line of a target river channel, provided by an embodiment of the present invention.

[0069] Figure 3 A schematic diagram of the bridge backwater inundation range corresponding to an adaptive river cross-section sample point provided in an embodiment of the present invention;

[0070] Figure 4 This is a schematic diagram of the flooding range of a bridge provided in an embodiment of the present invention. Detailed Implementation

[0071] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0072] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0073] In this invention, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between the associated objects, indicating that three relationships can exist.

[0074] like Figure 1 As shown, Figure 1 A flowchart illustrating a method for analyzing bridge flooding caused by flash floods, provided in this embodiment of the invention, specifically includes the following steps:

[0075] S10: Extract the centerline of the target river channel based on the digital elevation model data of the river area to be analyzed and the location of the target bridge.

[0076] The river area to be analyzed refers to the area where it is assessed whether there is potential for bridge flooding due to flash floods. This river area includes multiple target points at river cross-sections, as well as surrounding landscape elements such as trees, hillsides, and buildings, including villages and bridges. Target points at river cross-sections are specific cross-sections located around the river that need to be tested to determine if they are within the potential flooding zone for bridges. The target bridge can be any bridge within the river area to be analyzed. The target river is the river closest to the target bridge. However, this is not a limitation; the invention is not specifically restrictive, and those skilled in the art can set the appropriate parameters based on the actual situation.

[0077] Specifically, the digital elevation model data of the river area to be analyzed and the location of the target bridge are obtained. Based on the obtained digital elevation model data and the location of the target bridge, the centerline of the target river is extracted.

[0078] Optionally, based on the above embodiments, in some embodiments of the present invention, one implementation of S10 may be:

[0079] S101: Based on the digital elevation model data, obtain the river network according to the flow direction and confluence characteristics of multiple rivers in the river area to be analyzed.

[0080] Specifically, based on the obtained digital elevation model data, the flow direction of multiple rivers within the river area to be analyzed is analyzed, and the confluence characteristics of multiple rivers are calculated. Based on the flow direction and confluence characteristics of multiple rivers, the river network is obtained.

[0081] It should be noted that after obtaining the digital elevation model data, the data is first preprocessed by filling depressions to eliminate interference from false depressions.

[0082] S102: In the river network, determine the target river channel that is closest to the target bridge location, and extract the initial river channel centerline of the target river channel through the centerline transformation algorithm.

[0083] Among them, the central axis transformation algorithm refers to a mathematical method that extracts the central skeleton of arbitrary shapes by simulating the boundary erosion inwards at the same time, or a mathematical method that extracts the central skeleton of arbitrary shapes by simulating the equidistant points from the interior points to the boundary points.

[0084] S103: Perform geometric smoothing on the initial river channel centerline to obtain the target river channel centerline.

[0085] Specifically, after obtaining the river network within the river area to be analyzed, the target river closest to the target bridge location is determined in the river network. The initial river centerline of the target river is automatically extracted from the river network using the centerline transformation algorithm, and the initial river centerline is geometrically smoothed to obtain the target river centerline.

[0086] For example, refer to Figure 2 As shown, Figure 2 This is a schematic diagram illustrating the extraction of the centerline of a target river channel according to an embodiment of the present invention. The centerline of the target river channel is obtained by taking the location of a target bridge, such as the Huamen Village Bridge, as the starting point.

[0087] It should be noted that after obtaining the centerline of the target river channel, it is necessary to further extract the projected coordinate system of the target river channel centerline and the projected coordinate system of the digital elevation model data, and determine whether the projected coordinate system of the target river channel centerline is consistent with the projected coordinate system of the digital elevation model data. If they are inconsistent, the projected coordinate system of the target river channel centerline should be transformed to the projected coordinate system of the digital elevation model data, so as to facilitate the subsequent analysis of bridge flooding caused by flash floods.

[0088] Thus, this embodiment can automatically extract the centerline of the target river in the river network without manual interpretation on the topographic map, improving the efficiency of obtaining the river centerline. Furthermore, geometric smoothing of the initial river centerline eliminates interference from jagged fluctuations, improving the accuracy of obtaining the river centerline.

[0089] S11: Based on the first elevation of multiple preset river cross-section sample points corresponding to the target river centerline, determine the river gradient, backwater length, and terrain complexity index corresponding to the target river centerline.

[0090] Among them, the preset river cross-section sample points refer to the river cross-section sample points sampled along the center line of the target river at preset intervals, such as 100m.

[0091] Optionally, based on the above embodiments, in some embodiments of the present invention, one implementation of S11 may be:

[0092] S111: Determine the river gradient based on the first elevation of multiple preset river cross-section sample points and the preset river gradient calculation formula.

[0093] Optionally, based on the above embodiments, in some embodiments of the present invention, one implementation of S111 may be:

[0094] S1111: Calculate the local gradient of each preset river section sample point based on the first elevation of multiple preset river section sample points and the formula for calculating the local gradient of the river section.

[0095] Specifically, for each preset river section sample point, the local gradient of the river section is calculated based on the first elevation of each preset river section sample point, the first elevation of the next adjacent preset river section sample point, and the local gradient calculation formula of the river section.

[0096] Optionally, based on the above embodiments, in some embodiments of the present invention, the formula for calculating the local gradient of a river section may be limited by the following expression:

[0097]

[0098] in, Indicates the first i The local gradient of the river section corresponding to each preset river cross-section sample point Indicates the first i The length of the river segment corresponding to each preset river cross-section sample point. Indicates the first i The first elevation corresponding to each preset river cross-section sample point Indicates the first i+ The first elevation corresponding to a preset river cross-section sample point.

[0099] S1112: Determine the river gradient based on the local gradient of multiple river sections and the preset river gradient calculation formula.

[0100] Specifically, the local gradients of multiple river sections are substituted into the preset river gradient calculation formula to obtain the river gradient.

[0101] Optionally, based on the above embodiments, in some embodiments of the present invention, the preset river gradient calculation formula may be limited by the following expression:

[0102]

[0103] in, Indicates the river gradient. n This indicates the total number of sample points for multiple preset river cross-sections.

[0104] S112: Determine the dammed length based on the river gradient and the preset dammed length calculation formula.

[0105] Specifically, the obtained river gradient is substituted into the preset formula for calculating the backwater length to determine the backwater length.

[0106] Optionally, based on the above embodiments, in some embodiments of the present invention, the preset backwater length calculation formula may be limited by the following expression:

[0107]

[0108] in, L Indicates the length of the dammed water. h Indicates the height of the target bridge. λThe value represents the backwater length correction factor, which can be adaptively determined according to the river gradient and ranges from 1 to 2.5, but is not limited thereto. This invention does not impose specific limitations, and those skilled in the art can set it according to the actual situation.

[0109] S113: Based on the first elevation of multiple preset river cross-section sample points, obtain the river longitudinal slope change rate, river plane curvature, and surface roughness.

[0110] Optionally, based on the above embodiments, in some embodiments of the present invention, the formula can be used. Obtain the rate of change of the longitudinal slope of the river channel, where, Indicates the first i- The first elevation corresponding to a preset river cross-section sample point.

[0111] Optionally, based on the above embodiments, in some embodiments of the present invention, the formula can be used. Obtain the river channel planar curvature, where, a, b, c This represents the three sides of a triangle formed by any three consecutive preset river cross-section sample points from a set of preset river cross-section sample points. This represents the area of ​​a triangle formed by any three consecutive sample points of a predefined river channel cross-section.

[0112] Optionally, based on the above embodiments, in some embodiments of the present invention, the surface roughness is determined by calculating the first elevation standard deviation corresponding to a preset number of preset river cross-section sample points within a preset size window.

[0113] S114: The topographic complexity index is determined by weighted summation of the river channel longitudinal slope variation rate, river channel planar curvature, and surface roughness.

[0114] Specifically, the topographic complexity index is determined by weighted summation of the river channel longitudinal slope change rate, river channel planar curvature, and surface roughness.

[0115] Optionally, based on the above embodiments, in some embodiments of the present invention, according to the formula... Obtain the terrain complexity index, where, This represents the rate of change of the longitudinal slope of the river channel. Indicates the horizontal curvature of the river channel. Indicates surface roughness. The weighting coefficient representing the rate of change of the longitudinal slope of the river channel. The weighting coefficients representing the curvature of the river channel. The weighting coefficients representing surface roughness satisfy: ,for , as well as The specific value can be determined based on the preset type of the target river channel, using expert experience. This preset type could be, for example, a mountainous river channel or a meandering river channel in a plain. For instance, when the target river channel is a mountainous river channel, the value is set... , , However, this invention is not limited to this, and those skilled in the art can make settings according to the actual situation.

[0116] S12: Construct a gradient decay model for the backwater curve based on the river gradient and backwater length.

[0117] The gradient decay model of the backwater curve can be defined by the following expression:

[0118]

[0119] in, This represents the gradient decay of the backwater curve at each preset river cross-section sample point. This indicates the distance between the sample point of the preset river section and the target bridge location.

[0120] S13: Based on the backwater curve gradient decay model and the terrain complexity index, obtain the second elevation of the three adaptive river section sample points corresponding to each adaptive river section corresponding to the target river centerline.

[0121] Optionally, based on the above embodiments, in some embodiments of the present invention, one implementation of S13 may be:

[0122] S131: Based on the backwater curve gradient attenuation model, terrain complexity index, and preset spacing calculation formula, obtain the spacing between any two adjacent adaptive river sections among multiple adaptive river sections.

[0123] Specifically, after constructing the backwater curve gradient attenuation model, the spacing between any two adjacent adaptive river sections is obtained based on the backwater curve gradient attenuation model, the terrain complexity index, and the preset spacing calculation formula.

[0124] Optionally, based on the above embodiments, in some embodiments of the present invention, the preset spacing calculation formula may be limited by the following expression:

[0125]

[0126] in, This represents the distance between any two adjacent adaptive channel sections. This indicates the minimum cross-sectional spacing, which is used to ensure sampling density in areas with drastic changes in water backflow. For example, the minimum cross-sectional spacing could be 15 meters. This indicates the maximum cross-sectional spacing, which is used to avoid oversampling in flat areas. For example, the maximum cross-sectional spacing could be 100 meters. This represents the maximum gradient decay value of the backwater curve. For example, the maximum gradient decay value of the backwater curve could be 0.5. Indicates the terrain complexity index. This represents the gradient decay of the backwater curve at each preset river cross-section sample point, but is not limited thereto. This invention is not specifically limited, and those skilled in the art can set it according to the actual situation.

[0127] S132: Based on multiple intervals, obtain the initial adaptive river channel cross-section sample points for each adaptive river channel cross-section through a reverse indexing mechanism.

[0128] Here, the initial adaptive channel cross-section sample points refer to the adaptive channel cross-section sample points located on the centerline of the target channel for each adaptive channel cross-section. For example... Figure 3 As shown in the above embodiment, the initial adaptive river section sample point corresponding to the adaptive river section 10 is the river section sample point A located on the center line of the target river, but it is not limited to this. The present invention does not specifically limit it, and those skilled in the art can set it according to the actual situation.

[0129] Optionally, based on the above embodiments, in some embodiments of the present invention, one implementation of S132 may be:

[0130] According to the formula Obtain the distance from the initial adaptive river cross-section sample point to the starting point of the target river centerline, where, This represents the distance from the initial adaptive river cross-section sample point to the starting point of the target river centerline. This represents the total length of the target river channel centerline. This represents the distance from the target bridge location to the initial adaptive river cross-section sample point corresponding to each adaptive river cross-section.

[0131] The initial adaptive channel cross-section sample points are obtained for each adaptive channel cross-section using the centerline geometry object and various distances.

[0132] S133: Based on the initial adaptive river section sample points and the adjacent initial adaptive river section sample points, determine the three adaptive river section sample points corresponding to each adaptive river section.

[0133] Specifically, after obtaining the initial adaptive river section sample points, the tangent vector is first calculated based on the upstream adjacent points. When there are no upstream adjacent points, the tangent vector is calculated based on the downstream adjacent points. The normal vector is obtained based on the tangent vector. The two river section sample points at a preset distance on both sides of the normal vector are determined as the other two adaptive river section sample points corresponding to the adaptive river section. In this way, the three adaptive river section sample points corresponding to each adaptive river section are obtained.

[0134] For example, following the above embodiments, refer to the following... Figure 3 As shown, the adaptive river section 10 corresponds to adaptive river section sample points A, B, and C, but is not limited thereto. This invention is not specifically limited, and those skilled in the art can set them according to actual conditions.

[0135] S134: Calculate the second elevation corresponding to the three adaptive river section sample points according to the preset elevation calculation formula.

[0136] The formula for calculating the preset elevation can be defined by the following expression:

[0137]

[0138] in, This represents the distance from the target bridge location to the initial adaptive river channel cross-section sample point corresponding to each adaptive river channel cross-section. Indicates the bridge deck elevation of the target bridge. This represents the second elevation of the three adaptive river channel sample points corresponding to each adaptive river channel section.

[0139] S14: Based on digital elevation model data, multiple second elevations, and a preset comprehensive weight function, the third elevation of each target point at the river section is determined using the terrain factor weighted inverse distance weight interpolation method.

[0140] The preset comprehensive weight function is determined based on the distance weights of the adaptive river cross-section sample points and the target points of the river cross-section, as well as the weights of the terrain factors.

[0141] Optionally, based on the above embodiments, in some embodiments of the present invention, the method further includes the following before performing S14:

[0142] S20: Obtain initial digital elevation model data, perform deep pit preprocessing on the initial digital elevation model data, and obtain digital elevation model data.

[0143] Specifically, the initial digital elevation model data is obtained, and the initial digital elevation model data is preprocessed with a deep pit to obtain the digital elevation model data.

[0144] Optionally, the initial digital elevation model data can be processed by neighborhood median filtering to detect pits with a depth exceeding a set threshold, such as 8m. The pits can then be preprocessed using the median filling method to obtain the digital elevation model data.

[0145] S21: Based on digital elevation model data, perform terrain factor raster processing to obtain the first terrain factor parameters corresponding to multiple river cross-section target points.

[0146] The first topographic factor parameters include: the first river channel longitudinal slope variation rate, the first river channel planar curvature, the first slope aspect, and the first surface roughness.

[0147] S22: Determine the terrain factor weights based on the first terrain factor parameters corresponding to the target points of each river section and the second terrain factor parameters corresponding to multiple adaptive river section sample points.

[0148] The second topographic factor parameters include: river channel longitudinal slope variation rate, river channel plane curvature, slope aspect, and surface roughness.

[0149] Specifically, the first topographic factor parameters corresponding to each target point of the river section are substituted into the topographic factor weight calculation formula along with the second topographic factor parameters corresponding to multiple adaptive river section sample points to determine the weights of multiple topographic factors corresponding to each target point of the river section.

[0150] Optionally, based on the above embodiments, in some embodiments of the present invention, the formula for calculating the terrain factor weights may be limited by the following expression:

[0151]

[0152] in, This represents the rate of change of the longitudinal slope of the first river channel. Indicates the planar curvature of the first river channel. Indicates the first surface roughness. Indicates the first slope direction. Indicates slope direction. express Normalized weighting coefficients express Normalized weighting coefficients express Normalized weighting coefficients express The normalized weight coefficients satisfy ,for , , as well as The specific values ​​can be determined based on topographic factor parameters and expert experience. For example, when the rate of change of river channel longitudinal slope and the river channel horizontal curvature change significantly, the following settings can be used: , , , However, this invention is not limited to this; those skilled in the art can make modifications according to the actual situation. The characteristic scale parameter represents the rate of change of the longitudinal slope of the first river channel and the corresponding rate of change of the longitudinal slope of the river channel. The first channel plane curvature and the corresponding characteristic scale parameter. This represents the first surface roughness and the characteristic scale parameter corresponding to the surface roughness.

[0153] S23: Determine the distance weights based on the reciprocal of the distances between the target points of each river section and the sample points of multiple adaptive river sections.

[0154] Specifically, the distances between target points at each river cross-section and multiple adaptive river cross-section sample points are calculated sequentially, and the reciprocal of the distance is determined as the distance weight.

[0155] S24: Perform a product operation on the distance weight and the terrain factor weight to determine the preset comprehensive weight function.

[0156] Specifically, after obtaining the distance weight and terrain factor weight, the distance weight and terrain factor weight are multiplied to determine the preset comprehensive weight function.

[0157] Optionally, the preset comprehensive weight function can be limited by the following expression:

[0158]

[0159] in, This indicates the preset comprehensive weight function. Indicates distance weight, This indicates the weight of the terrain factor.

[0160] Optionally, based on the above embodiments, in some embodiments of the present invention, one implementation of S14 may be:

[0161] S141: Downsampling is performed on the digital elevation model data.

[0162] S142: For the digital elevation model data after downsampling, the initial elevation of multiple river cross-section target points is determined by using the terrain factor weighted inverse distance weight interpolation method based on multiple second elevations and a preset comprehensive weight function.

[0163] Among them, the terrain factor weighted inverse distance interpolation method refers to combining terrain factors with the inverse distance weight interpolation method, so as to take into account the similarity measurement of terrain features between the adaptive river cross-section sample points and the river cross-section target points, thereby improving accuracy.

[0164] Specifically, the acquired digital elevation model data is downsampled to obtain downsampled digital elevation model data. Based on the downsampled digital elevation model data, the initial elevations of multiple river cross-section target points are determined using a terrain factor weighted inverse distance weight interpolation method according to multiple second elevations and a preset comprehensive weight function.

[0165] S143: For digital elevation model data, based on the initial elevations of multiple river cross-section target points, multiple second elevations, and a preset comprehensive weight function, the third elevation of each river cross-section target point is determined using the terrain factor weighted inverse distance weight interpolation method.

[0166] Specifically, after obtaining the initial elevations of multiple target points at river cross sections, the third elevation of each target point at the river cross section is determined based on the digital elevation model data, the initial elevations of the multiple target points at the river cross sections, the multiple second elevations, and the preset comprehensive weight function, using the terrain factor weighted inverse distance weight interpolation method.

[0167] Thus, in this embodiment, interpolation is first performed on the downsampled digital elevation model data to reduce computational complexity. Then, the initial elevations of multiple river cross-section target points are used to interpolate the un-downsampled digital elevation model data, which preserves the spatial details of the original digital elevation model data and improves the accuracy of obtaining the initial elevations of multiple river cross-section target points.

[0168] S15: Determine the flooding range based on the preset dividing line corresponding to the target bridge, the preset reference directional distance, and multiple target points of the river cross section.

[0169] Optionally, based on the above embodiments, in some embodiments of the present invention, S15 may be implemented as follows:

[0170] S151: Construct a preset dividing line based on the set of coordinates of the target bridge.

[0171] The coordinate location set includes: the coordinate location of the left end point of the target bridge. and the coordinates of the right endpoint .

[0172] Specifically, a pre-defined dividing line is constructed based on the coordinates of the left and right ends of the target bridge.

[0173] Optionally, based on the above embodiments, in some embodiments of the present invention, the preset dividing line may be defined by the following expression:

[0174]

[0175] in, , , .

[0176] S152: Calculate the preset reference directed distance between the sample points of the initial adaptive channel section corresponding to the second adaptive channel section and the preset dividing line.

[0177] Specifically, the directed distance between the initial adaptive river cross-section sample point corresponding to the second adaptive river cross-section and the preset dividing line is calculated as the preset reference directed distance.

[0178] Optionally, the coordinates of the initial adaptive channel cross-section sample points corresponding to the second adaptive channel cross-section are set as follows: According to the formula Determine the preset reference directional distance.

[0179] S153: Calculate the directed distance between the target point of each river section and the preset dividing line.

[0180] S154: Determine the flooding range based on the preset reference directional distance and multiple directional distances.

[0181] Specifically, for each target point at a river cross-section, the directed distance between it and a preset dividing line is calculated. The sign of this directed distance is compared with a preset reference directed distance. If the sign of the directed distance is opposite to the preset reference directed distance, the point is not within the inundation range; otherwise, it is within the inundation range. This process is used to determine the inundation range. Figure 4 As shown.

[0182] S16: Based on multiple third elevations and the inundation range, the inundation analysis results are obtained.

[0183] Specifically, after obtaining the inundation range, the inundation analysis results are determined based on the inundation range and the third elevation corresponding to the target points of each river section within the inundation range.

[0184] Thus, the method for analyzing bridge flooding caused by flash floods provided in this embodiment extracts the target river centerline based on the digital elevation model data of the river area to be analyzed and the location of the target bridge. The river area to be analyzed includes multiple target points of river cross sections. Based on the first elevation of multiple preset river cross section sample points corresponding to the target river centerline, the river gradient, flood length, and terrain complexity index corresponding to the target river centerline are determined. A flood curve gradient attenuation model is constructed based on the river gradient and flood length. Based on the flood curve gradient attenuation model and the terrain complexity index, the second elevation of three adaptive river cross section sample points corresponding to each adaptive river cross section corresponding to the target river centerline is obtained. Based on the digital elevation model data, multiple second elevations, and a preset comprehensive weight function, the third elevation of each target point of the river cross section is determined using a terrain factor weighted inverse distance weight interpolation method. The preset comprehensive weight function is determined based on the distance weights of the adaptive river cross section sample points and the target points of the river cross section, as well as the terrain factor weights. The inundation range is determined based on the preset dividing lines corresponding to the target bridge, the preset directional reference distances, and multiple target points at river cross-sections. Inundation analysis results are obtained based on multiple third elevations and the inundation range. This eliminates the need for manual interpretation of topographic maps to extract the river centerline, improving the accuracy of centerline extraction. In complex terrain conditions, it considers terrain complexity, avoids insufficient sampling data, and improves the accuracy and efficiency of bridge flooding analysis during flash floods.

[0185] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, databases, or other media used in the embodiments provided by this invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static random access memory (SRAM) and dynamic random access memory (DRAM), etc.

[0186] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0187] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for analyzing bridge flooding caused by flash floods, characterized in that, include: Based on the digital elevation model data of the river channel area to be analyzed and the location of the target bridge, the centerline of the target river channel is extracted. The river channel area to be analyzed includes multiple target points of the river channel cross section. Based on the first elevation of multiple preset river cross-section sample points corresponding to the target river centerline, determine the river gradient, backwater length, and terrain complexity index corresponding to the target river centerline. Based on the riverbed gradient and the impoundment length, a gradient decay model for the impoundment curve is constructed; the gradient decay model for the impoundment curve is defined by the following expression: ； in, This represents the gradient decay of the backwater curve at each preset river cross-section sample point. This indicates the distance between the sample point of the preset river section and the target bridge location. λ represents the river channel gradient, and λ represents the backwater length correction factor. L Indicates the length of the dammed water; Based on the backwater curve gradient decay model and the terrain complexity index, the second elevation of the three adaptive river section sample points corresponding to each adaptive river section corresponding to the target river centerline is obtained. Based on digital elevation model data, multiple second elevations, and a preset comprehensive weight function, the third elevation of each target point in a river section is determined using a terrain factor weighted inverse distance weight interpolation method. The preset comprehensive weight function is determined based on adaptive river section sample points, the distance weight of the target point in the river section, and the terrain factor weight. The inundation range is determined based on the preset dividing line corresponding to the target bridge, the preset reference directional distance, and multiple target points of the river section. The inundation analysis results were obtained based on multiple third elevations and the inundation range.

2. The method according to claim 1, characterized in that, The step of extracting the centerline of the target river channel based on the digital elevation model data of the river area to be analyzed and the location of the target bridge includes: Based on the digital elevation model data, a river network is obtained according to the flow direction and confluence characteristics of multiple rivers within the river area to be analyzed; In the river network, identify the target river channel closest to the target bridge location, and extract the initial river channel centerline of the target river channel using a centerline transformation algorithm; The initial river channel centerline is geometrically smoothed to obtain the target river channel centerline.

3. The method according to claim 2, characterized in that, The step of determining the river gradient, backwater length, and terrain complexity index corresponding to the target river centerline based on the first elevation of multiple preset river cross-section sample points corresponding to the target river centerline includes: The river gradient is determined based on the first elevation of multiple preset river cross-section sample points and the preset river gradient calculation formula. The water damming length is determined based on the river gradient and the preset formula for calculating the water damming length. Based on the first elevation of the multiple preset river cross-section sample points, the river longitudinal slope change rate, river plane curvature, and surface roughness are obtained. The terrain complexity index is determined by weighted summation of the river channel longitudinal slope variation rate, river channel planar curvature, and surface roughness.

4. The method according to claim 3, characterized in that, The determination of the river gradient based on the first elevation of multiple preset river cross-section sample points and a preset river gradient calculation formula includes: Based on the first elevation of multiple preset river section sample points and the formula for calculating the local gradient of the river section, the local gradient of the river section at each preset river section sample point is calculated. The river gradient is determined based on the local gradients of multiple river sections and a preset river gradient calculation formula.

5. The method according to claim 4, characterized in that, The formula for calculating the local gradient of the river section is defined by the following expression: ； in, Indicates the first i The local gradient of the river section corresponding to each preset river cross-section sample point L i Indicates the first i The length of the river segment corresponding to each preset river cross-section sample point. Indicates the first i The first elevation corresponding to each preset river cross-section sample point Indicates the first i +1 preset river cross-section sample points corresponding to the first elevation; The preset river gradient calculation formula is defined by the following expression: ； in, n This indicates the total number of sample points for multiple preset river cross-sections. The formula for calculating the preset backwater length is defined by the following expression: ； in, h Indicates the height of the target bridge.

6. The method according to claim 5, characterized in that, The step of obtaining the second elevation of three adaptive river cross-section sample points corresponding to each adaptive river cross-section corresponding to the target river centerline based on the backwater curve gradient attenuation model and the terrain complexity index includes: Based on the backwater curve gradient decay model, terrain complexity index, and preset spacing calculation formula, the spacing between any two adjacent adaptive river sections in multiple adaptive river sections is obtained. Based on multiple intervals, the initial adaptive river channel cross-section sample points are obtained through a reverse indexing mechanism. Based on the initial adaptive river section sample points and the adjacent initial adaptive river section sample points, determine the three adaptive river section sample points corresponding to each adaptive river section. Calculate the second elevation corresponding to the three adaptive river cross-section sample points according to the preset elevation calculation formula; The formula for calculating the preset spacing is defined by the following expression: ； in, This represents the distance between any two adjacent adaptive channel sections. Indicates the minimum cross-sectional spacing. Indicates the maximum cross-sectional spacing. denoted by , where represents the maximum gradient decay value of the backwater curve, and C represents the terrain complexity index; The preset elevation calculation formula is defined by the following expression: ； in, This represents the distance from the target bridge location to the initial adaptive river channel cross-section sample point corresponding to each adaptive river channel cross-section. Indicates the bridge deck elevation of the target bridge. This represents the second elevation of the three adaptive river channel sample points corresponding to each adaptive river channel section.

7. The method according to claim 6, characterized in that, Before determining the third elevation of each river cross-section target point using a terrain factor weighted inverse distance weighting interpolation method based on digital elevation model data, multiple second elevations, and a preset comprehensive weighting function, the process further includes: Obtain initial digital elevation model data, and perform deep pit preprocessing on the initial digital elevation model data to obtain the digital elevation model data; Based on the digital elevation model data, terrain factor raster processing is performed to obtain the first terrain factor parameters corresponding to multiple river cross-section target points. The terrain factor weights are determined based on the first terrain factor parameters corresponding to each target point of the river section and the second terrain factor parameters corresponding to multiple adaptive river section sample points. The distance weights are determined based on the reciprocals of the distances between each target point of the river cross section and multiple adaptive river cross section sample points. The distance weight and the terrain factor weight are multiplied to determine the preset comprehensive weight function.

8. The method according to claim 7, characterized in that, The process of determining the third elevation of each river cross-section target point based on digital elevation model data, multiple second elevations, and a preset comprehensive weight function, using a terrain factor weighted inverse distance weight interpolation method, includes: The digital elevation model data is downsampled. For the digital elevation model data after downsampling, the initial elevations of multiple river cross-section target points are determined by using a terrain factor weighted inverse distance weight interpolation method based on multiple second elevations and a preset comprehensive weight function. Based on the digital elevation model data, the third elevation of each river cross-section target point is determined using the terrain factor weighted inverse distance weight interpolation method, according to the initial elevation of the multiple river cross-section target points, the multiple second elevations, and the preset comprehensive weight function.

9. The method according to claim 8, characterized in that, The process of determining the inundation range based on the preset dividing line corresponding to the target bridge, the preset reference directional distance, and multiple target points of the river cross-section includes: Based on the set of coordinates of the target bridge, construct the preset dividing line; Calculate the preset reference directed distance between the initial adaptive river cross section sample point corresponding to the second adaptive river cross section and the preset dividing line; Calculate the directed distance between each target point in the river channel cross-section and the preset dividing line; The flooding range is determined based on the preset reference directional distance and multiple directional distances.

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