A rapid assessment method for waterlogging risk based on terrain smoothing

Abstract

The present invention provides a method for rapid assessment of urban flooding risk based on terrain smoothing, comprising the following steps: S1. interpolating embankment elevation points using spatial interpolation technology to generate a starting water level surface, combining the starting water level surface with smoothing high-precision digital elevation model data to generate a virtual terrain; S2. performing spatial interpolation calculation on inland river water level monitoring point data to generate surface data, assuming that the surface data at this time is the water level surface data of the monitoring area; S3. performing spatial overlay analysis on the virtual terrain described in S1 and the water level surface data described in S2 to generate the inundation surface and inundation depth of the monitoring area; S4. extracting urban flooding risk objects by combining the inundation surface, inundation depth and underlying surface information of the monitoring area, thereby solving the technical problem of misjudgment of urban flooding risk in low-lying underground areas in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of waterlogging risk assessment, and in particular to a method for rapid waterlogging risk assessment based on terrain smoothing. Background Art

[0002] Effective and rapid urban flooding risk assessment and automated extraction of flood risk targets are crucial for early warning and assessment of urban flooding disasters. Traditional urban flooding simulations typically employ hydrological and hydrodynamic methods, comprehensively considering the impact between drainage networks and river channels, incorporating extensive underlying surface information and numerous model parameters. These methods are also time-consuming and expensive to calculate. Therefore, currently, urban flooding simulations integrated with drainage networks are suitable for detailed, small-scale flooding analysis. However, large-scale, city-level flooding analysis and assessment require rapid and efficient response times and large-scale flooding risk calculations. In many plains, the height of inland river levees is equal to the height of the land. During floods, not only is the river flow connected, but it can be assumed that the flow is connected across the entire plain area. This allows for spatial interpolation of river water levels to generate the inundation range for the entire plain. The plain area has a gentle terrain, and the combination of water level and spatial interpolation technology has strong applicability, but misjudgments still occur, including local areas being judged as flood risk areas when no floods occur, and a small number of low-lying areas being identified as flood risk areas. Summary of the Invention

[0003] The purpose of the present invention is to provide a method and method for rapid assessment of urban flooding risk based on smooth terrain, so as to solve the technical problem of misjudgment of urban flooding risk in underground low-lying areas existing in the prior art.

[0004] The present invention provides a rapid assessment method for urban flooding risk based on terrain smoothing, comprising the following steps: S1. interpolating embankment elevation points using spatial interpolation technology to generate a starting water level surface, combining the starting water level surface with smoothing high-precision digital elevation model data to generate a virtual terrain; S2. performing spatial interpolation calculation on inland river water level monitoring point data to generate surface data, assuming that the surface data at this time is the water level surface data of the monitoring area; S3. performing spatial overlay analysis on the virtual terrain described in S1 and the water level surface data described in S2 to generate the inundation surface and inundation depth of the monitoring area; S4. extracting urban flooding risk objects by combining the inundation surface, inundation depth and underlying surface information of the monitoring area.

[0005] Furthermore, the monitoring area is a plain area, and the water flow in the entire plain area is connected.

[0006] Furthermore, the S1 specifically includes the following steps: S11. Acquire high-precision digital elevation model data, inland river channel vector data, and inland river water level monitoring station data of the monitoring area, and make them have the same spatial coordinate system; S12. Select embankment points on the inland river embankment near the inland river water level monitoring point to obtain elevation data of the embankment points; S13. Perform spatial interpolation calculation on the embankment points to obtain embankment surface data, and set the embankment surface as the starting water level surface during the flooding process; S14. Spatially superimpose the starting water level surface and the high-precision digital elevation model data, compare the elevation values ​​of the starting water level surface and the high-precision digital elevation model data, retain the larger elevation value of the two, and generate a virtual terrain. The calculation formula is as follows:

[0007]

[0008] Among them, H vt is the elevation value of the virtual terrain, H s is the elevation of the starting water level, H dem It is the elevation value of the high-precision digital elevation model data.

[0009] Furthermore, the specific steps of S2 for obtaining the water level surface data of the monitoring area include: S21. Obtaining the inland river water level monitoring point data and the elevation data of the embankment points in S12, and making them have the same spatial coordinate system; S22. Comparing the sizes of all the inland river water level monitoring point data and the corresponding embankment point elevation data in the monitoring area. If the former are greater than the latter, proceed to step S23; otherwise, it is judged that there is no flooding risk in the monitoring area; S23. Performing spatial interpolation on the inland river water level monitoring point data to generate flooding surface data of the monitoring area.

[0010] Furthermore, the specific steps of S3 include: S31. Obtaining water level surface data of the monitoring area, placing it in the same spatial coordinate system as the virtual terrain, and making the grid sizes of the two surface data the same and spatially matched, and performing spatial overlay analysis; S32. Calculating the submerged water depth value of each grid, the calculation formula is as follows:

[0011]

[0012] Among them, D is the submerged water depth data, H wl Water level data of the water level surface, H vt The elevation value of the virtual terrain,

[0013] The monitoring area with flooding depth value greater than zero constitutes the flooding surface of the monitoring area.

[0014] Furthermore, the specific steps of S4 include: S41. Obtaining the surface vector data of the spatial object of the underlying surface and placing it in the same spatial coordinate system as the virtual terrain; S42. Determining whether the spatial object and the flooded surface of the monitoring area intersect in space. If so, determining that the spatial object is a waterlogging risk object.

[0015] The present invention provides a rapid assessment method for urban flooding risk based on terrain smoothing. By utilizing the strong autocorrelation of water levels in plain areas during floods, the method uses inland river water levels and high-precision digital elevation models (DEMs) to construct an assessment method for urban flooding risk based on terrain smoothing. This method can effectively provide early warning and prediction for urban flooding risks, solves the technical problem of misjudgment of urban flooding risks in underground low-lying areas in the existing technology, and can quickly calculate the flooded range, flooded water depth, and risk objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A calculation flow chart of a rapid assessment method for waterlogging risk based on terrain smoothing provided in this embodiment;

[0018] Figure 2 Schematic diagram of the spatial relationship between water level monitoring points, embankment points and inland river channels provided in this embodiment;

[0019] Figure 3 Schematic diagram of spatial comparison of the starting water level, DEM data, and virtual terrain provided in this embodiment;

[0020] Figure 4 This is a schematic diagram showing the water level data, virtual terrain, flooded area and water depth comparison of the monitoring area provided in this embodiment. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] This embodiment provides a method for rapid assessment of waterlogging risk based on terrain smoothing, which uses water level monitoring data and a high-precision digital elevation model (DEM) to quickly assess waterlogging risk in plain areas. The operation process of this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0023] S1. Use the inverse distance weighted (IDW) spatial interpolation technique to interpolate the levee elevation points to generate a starting water level surface. Combine the starting water level surface with high-precision DEM data to smooth the DEM and generate a virtual terrain. The specific steps include the following:

[0024] Step S11. Obtain DEM data for the plain area, such as 2m*2m DEM data based on drone aerial photography, inland river vector data, and inland river water level monitoring station data, and make them have the same spatial coordinate system;

[0025] Step S12. Combine the inland river vector data and high-precision remote sensing image data to select points on the inland river embankment. The points are evenly distributed in the entire plain area and ensure that the embankments near the inland river water level monitoring stations are included. The number of points must meet the spatial interpolation requirements. Combined with the high-precision DEM data, the elevation data of the embankment points are obtained, such as Figure 2 The figure shows the spatial relationship between water level monitoring points, embankment points and inland river channels.

[0026] Step S13: Perform IDW spatial interpolation calculation on the embankment points to obtain embankment surface data, assuming that the embankment surface is the starting water level surface during the flooding process.

[0027] Step S14: Spatially overlay the starting water level surface and the high-precision DEM data. When comparing the elevation values ​​of the starting water level surface and the high-precision DEM, retain the larger elevation value of the two to generate a virtual terrain.

[0028] The calculation formula is as follows:

[0029]

[0030] Among them, H vt is the elevation value of the virtual terrain, H s is the elevation of the starting water level, H dem It is the elevation value of high-precision DEM.

[0031] Figure 3 Schematic diagram of spatial comparison of starting water level, DEM data and virtual terrain.

[0032] S2. Perform IDW spatial interpolation calculation on the inland river water level monitoring point data to obtain the water level surface data of the plain area, which specifically includes the following steps:

[0033] Step S21. Acquire the inland river water level monitoring point data and the levee elevation data near the water level monitoring site extracted in step S12, and make them have the same spatial coordinate system as other data;

[0034] Step S22: Compare the data of all inland river water level monitoring points with the levee elevation data near the corresponding water level stations. If the former are greater than the latter, proceed to step S23; otherwise, determine that there is no flooding risk.

[0035] Step S23. Taking the plain area as the boundary, perform spatial interpolation on the inland river water level monitoring point data to generate the water level data of the monitoring area water level surface (H wl ).

[0036] S3. Perform spatial overlay analysis on the plain area water level surface data and virtual terrain to generate the plain area inundation surface and inundation depth, specifically including the following steps:

[0037] S31. According to the needs, obtain the real-time monitoring surface data of the water level in the plain area, and make the spatial overlay analysis of the water level surface data in the plain area and the virtual terrain be placed in the same spatial coordinate system, and the surface data grid size is the same and the space is matched.

[0038] S32. Calculate the flooding depth value for each grid, that is, subtract the elevation value of the virtual terrain from the water level data of the water level surface. If the former is greater than the latter, the area is at risk of flooding. The calculation formula is as follows:

[0039]

[0040] Among them, D is the submerged water depth data, H wl Water level data of the water level surface, H vt The elevation value of the virtual terrain.

[0041] Figure 4 This is a schematic diagram comparing water level data, virtual terrain, inundation range, and water depth. The monitoring area with inundation depth values ​​greater than zero constitutes the plain area inundation surface.

[0042] S4. Rapidly identify flood risk areas based on information on the inundation area, inundation depth, and underlying surface in the plain area. This includes the following steps:

[0043] S41. Obtain surface vector data for the underlying surface of spatial objects such as hazardous chemical enterprises, residential areas, shopping malls, agricultural and forestry land, and villages, and place them in the same spatial coordinate system as other data such as virtual terrain. The elevation of most spatial objects should be higher than the starting water surface, while the elevation of spatial objects in low-lying areas should be lower than the starting water surface.

[0044] S42. Determine whether the spatial object and the flooded surface intersect in space. If so, determine that the spatial object is an object with a risk of urban flooding. Otherwise, determine that there is no risk of urban flooding.

[0045] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0046] The above-mentioned specific implementation methods are used to illustrate the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the scope of protection of the claims shall fall within the scope of protection of the present invention.

Claims

1. A rapid assessment method for waterlogging risk based on terrain smoothing, characterized in that: The steps include: S1. Using spatial interpolation technology to interpolate the embankment elevation points to generate a starting water level surface, and combining the starting water level surface with high-precision digital elevation model data to smooth and generate a virtual terrain; S2. Perform spatial interpolation calculation on the inland river water level monitoring point data to generate surface data, assuming that the surface data at this time is the water level surface data of the monitoring area; S3. Perform spatial overlay analysis on the virtual terrain data described in S1 and the water level surface data described in S2 to generate the inundation surface and inundation depth of the monitoring area; S4. Extract waterlogging risk targets based on the inundation area, inundation depth, and underlying surface information in the monitoring area; The S1 specifically includes the following steps: S11. Obtain high-precision digital elevation model data, inland river vector data, and inland river water level monitoring station data for the monitoring area, and make them have the same spatial coordinate system; S12. Selecting a dike point on the inland river dike near the inland river water level monitoring point to obtain elevation data of the dike point; S13. Performing spatial interpolation calculation on the embankment points to obtain embankment surface data, and setting the embankment surface as the starting water level surface during the flooding process; S14. Spatially superimpose the starting water level surface and the high-precision digital elevation model data, compare the elevation values ​​of the starting water level surface and the high-precision digital elevation model data, retain the larger elevation value of the two, and generate a virtual terrain. The calculation formula is as follows: Among them, H vt is the elevation value of the virtual terrain, H s is the elevation of the starting water level, H dem is the elevation value of the high-precision digital elevation model data; The specific steps of S2 for obtaining the water level data of the monitoring area include: S21 obtains the inland river water level monitoring point data and the elevation data of the embankment point in S12, and makes them have the same spatial coordinate system; S22. Compare the water level data of all inland river monitoring points within the monitoring area with the corresponding embankment elevation data. If the former are greater than the latter, proceed to step S23. Otherwise, it is determined that there is no flooding risk within the monitoring area. S23. Perform spatial interpolation on the inland river water level monitoring point data to generate flooded surface data for the monitoring area; The specific steps of S3 include: S31. Obtain the water level surface data of the monitoring area, place it in the same spatial coordinate system as the virtual terrain, and make sure that the grid size of the two surface data is the same and the space matches, and perform spatial overlay analysis; S32. Calculate the submerged water depth of each grid using the following formula: Among them, D is the submerged water depth data, H wl Water level data of the water level surface, H vt The elevation value of the virtual terrain, The monitoring area with inundation depth values ​​greater than zero constitutes the inundation surface of the monitoring area; The specific steps of S4 include: S41 obtains the surface vector data of the underlying space object so that it is placed in the same spatial coordinate system as the virtual terrain; S42. Determine whether the spatial object and the flooded surface of the monitoring area intersect in space. If so, determine that the spatial object is a waterlogging risk object.

2. The method for rapid assessment of waterlogging risk according to claim 1, characterized in that: The monitoring area is a plain area, and the water flow in the entire plain area is connected.

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