A method, device and medium for dividing and evaluating accessibility of an urban waterlogging-prone area

Abstract

The application relates to the technical field of disaster emergency processing, in particular to a city waterlogging-prone area division and accessibility evaluation method, device and medium, city DSM data and a preset floodwater level are acquired; a flood inundation model is created based on the city DSM data and the preset floodwater level, and a flood inundation area is extracted from the flood inundation model; city road network position data, drainage unit position data and the flood inundation area are superimposed on the same projection coordinate system to obtain a superimposition diagram; in the superimposition diagram, the flood inundation area is divided based on the relative positions of the city road network, the drainage unit and the flood inundation area, and a waterlogging-prone area is obtained; the distance from the waterlogging-prone area to surrounding emergency refuge sites is calculated, the refuge time of the waterlogging-prone area is calculated based on the distance; and the accessibility of the waterlogging-prone area is evaluated based on the refuge time of the waterlogging-prone area. The accessibility of the city waterlogging-prone area to the emergency refuge sites is accurately and efficiently evaluated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of disaster emergency handling, in particular to a method and device for dividing and evaluating the accessibility of urban flood-prone areas and a medium. BACKGROUND

[0002] At present, the research on urban flood disasters mostly focuses on the identification and prediction of flood-prone points. The identification of flood-prone points mainly combines digital elevation model (DEM), meteorological data and underground pipe network data, and largely depends on historical flood events (such as flood occurrence points, flooded water depth, rainfall) and historical experience information, so the identification of flood-prone points has strong subjectivity and low efficiency. The accessibility evaluation of emergency sites is a key link in flood disaster warning and rescue, and the existing technology mainly studies the identification method of flood-prone points and the risk analysis of flood disaster factors, but pays less attention to and evaluates the accessibility of flood-prone areas to adjacent emergency refuge sites, so that the flood identification system lacks completeness.

[0003] Therefore, how to finely divide urban flood-prone areas and accurately and efficiently evaluate the accessibility of urban flood-prone areas to emergency refuge sites is a problem to be solved. SUMMARY

[0004] The present application provides a method for dividing and evaluating the accessibility of urban flood-prone areas, which can finely divide urban flood-prone areas and accurately and efficiently evaluate the accessibility of urban flood-prone areas to emergency refuge sites.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0006] In a first aspect, the present application provides a method for dividing and evaluating the accessibility of urban flood-prone areas, which comprises:

[0007] obtaining urban DSM data and a preset flood water level;

[0008] creating a flood inundation model based on the urban DSM data and the preset flood water level, and extracting a flood inundation area from the flood inundation model;

[0009] superimposing the urban road network position data, the drainage unit position data and the flood inundation area in the same projection coordinate system to obtain a superimposed graph;

[0010] dividing the flood inundation area based on the relative positions of the urban road network, the drainage unit and the flood inundation area in the superimposed graph to obtain a flood-prone area;

[0011] calculating the distance from the flood-prone area to the surrounding emergency refuge sites, and calculating the refuge time of the flood-prone area based on the distance;

[0012] evaluating the accessibility of the flood-prone area based on the refuge time of the flood-prone area.

[0013] In a preferred example of the present application, the flood inundation model is created based on the urban DSM data and the preset flood water level, and the flood inundation area is extracted from the flood inundation model, including:

[0014] The flood inundation model is created by using an analysis tool in ArcGIS in combination with the urban DSM data and the preset flood water level;

[0015] The intersection boundary of the flood surface generated according to the preset flood water level and the DSM in the model is extracted to obtain the vector range of the flood inundation area.

[0016] In a preferred example of the present application, the flood inundation area is divided based on the relative positions of the urban road network, the drainage unit and the flood inundation area in the overlay diagram to obtain the waterlogging-prone area, including:

[0017] When the flood inundation area in the overlay diagram does not contain a drainage unit, the flood inundation area is divided into an independent waterlogging-prone area;

[0018] When the flood inundation area in the overlay diagram contains a road network or a drainage unit, the flood inundation area is divided along the boundary of the road network or the drainage unit to obtain a plurality of waterlogging-prone areas.

[0019] In a preferred example of the present application, when the flood inundation area in the overlay diagram contains a road network or a drainage unit, the flood inundation area is divided along the boundary of the road network or the drainage unit to obtain a plurality of waterlogging-prone areas, including:

[0020] When the road in the road network in the flood inundation area and the boundary of the flood inundation area form a closed area and the closed area is next to a plurality of drainage units, the closed area is divided into a waterlogging-prone area;

[0021] When the closed area is next to only one drainage unit, if the area of the closed area is smaller than the area of the drainage unit, the closed area is merged into the waterlogging-prone area in which the drainage unit is located.

[0022] In a preferred example of the present application, including:

[0023] The risk level of the waterlogging-prone area is calculated according to the data of the waterlogging-prone area, the meteorological data of the city and the human geography data of the city.

[0024] In a preferred example of the present application, the distance of the waterlogging-prone area to the surrounding emergency refuge sites is calculated, including:

[0025] It is judged whether the waterlogging-prone area contains a POI;

[0026] If the POI is included in the waterlogging-prone area, the coordinates of all POIs in the waterlogging-prone area are determined;

[0027] If the POI is not included in the waterlogging-prone area, the coordinates of the geometric center of the waterlogging-prone area are determined;

[0028] All emergency shelters within a 2-kilometer buffer radius from the coordinates are obtained;

[0029] The distance from the coordinates to the emergency shelters is calculated.

[0030] In a preferred example of the present application, the reachability of the waterlogging-prone area can be further determined based on the emergency time of the waterlogging-prone area, including:

[0031] The emergency times of all waterlogging-prone areas are normalized to obtain T values;

[0032] Waterlogging-prone areas with T values of 0-0.3 are rated as having good reachability, waterlogging-prone areas with T values of 0.4-0.6 are rated as having general reachability, and waterlogging-prone areas with T values of 0.7-1 are rated as having poor reachability.

[0033] In a preferred example of the present application, the reachability of the waterlogging-prone area can be further determined based on the emergency time of the waterlogging-prone area, including:

[0034] A flood prevention plan is developed in combination with the risk level and reachability of the waterlogging-prone area.

[0035] In a second aspect, the present application provides a device for dividing and evaluating the reachability of urban waterlogging-prone areas, the device comprising:

[0036] A flood inundation area obtaining module is configured to obtain urban DSM data and a preset floodwater level, create a flood inundation model based on the urban DSM data and the preset floodwater level, and extract a flood inundation area from the flood inundation model;

[0037] A waterlogging-prone area dividing module is configured to superimpose urban road network position data, drainage unit position data, and the flood inundation area on the same projection coordinate system to obtain a superimposition map, and divide the flood inundation area based on the relative positions of the urban road network, the drainage unit, and the flood inundation area in the superimposition map to obtain a waterlogging-prone area;

[0038] A reachability calculating module is configured to calculate the distance from the waterlogging-prone area to surrounding emergency shelters, calculate the emergency time of the waterlogging-prone area based on the distance, and evaluate the reachability of the waterlogging-prone area based on the emergency time of the waterlogging-prone area.

[0039] In a third aspect, the present application provides a computer-readable storage medium having a program stored thereon, wherein the program is executed by a processor to implement the method for dividing and evaluating the reachability of urban waterlogging-prone areas according to any one of the above aspects.

[0040] Compared with the prior art, the technical scheme provided by the embodiment of the application has at least the following beneficial effects:

[0041] The method for dividing and evaluating the accessibility of the urban flood-prone area provided by the application comprises the following steps: obtaining urban DSM data and a preset floodwater level; creating a flood inundation model based on the urban DSM data and the preset floodwater level, and extracting a flood inundation area from the flood inundation model; superimposing urban road network position data and drainage unit position data on the same projection coordinate system with the flood inundation area to obtain a superimposition diagram; dividing the flood inundation area based on the relative positions of the urban road network, the drainage unit and the flood inundation area in the superimposition diagram to obtain a flood-prone area; calculating the distance from the flood-prone area to a surrounding emergency refuge site, calculating the refuge time of the flood-prone area based on the distance; and evaluating the accessibility of the flood-prone area based on the refuge time of the flood-prone area. The method realizes fine division of the flood-prone area and accurate and efficient evaluation of the accessibility of the urban flood-prone area to the emergency refuge site. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The flowchart of the method for dividing and evaluating the accessibility of the urban flood-prone area provided by an embodiment of the application.

[0043] Figure 2 The superimposition diagram of the method for dividing and evaluating the accessibility of the urban flood-prone area provided by an embodiment of the application.

[0044] Figure 3 The schematic diagram of the accessibility of an emergency refuge site within a certain buffer radius range from a certain POI in the flood-prone area provided by an embodiment of the application.

[0045] Figure 4 The device diagram of the method for dividing and evaluating the accessibility of the urban flood-prone area provided by an embodiment of the application. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0047] In an embodiment of the application, a method for dividing and evaluating the accessibility of an urban flood-prone area is provided, as shown in Figure 1 The method comprises the following steps:

[0048] S100: Obtain city DSM data and preset flood water level;

[0049] Specifically, a digital surface model (DSM) of the city is obtained by means of oblique photogrammetry or laser radar measurement technology. The DSM refers to a ground elevation model containing the heights of buildings, bridges, trees and the like on the ground. The DSM model is city DSM data used to generate a flood inundation model. Flood water level data of flood events in the city in the past ten years is collected, and the mean value thereof is taken as the preset flood water level of the application.

[0050] S200: Create a flood inundation model based on the city DSM data and the preset flood water level, and extract a flood inundation area from the flood inundation model;

[0051] S300: Superimpose city road network position data and drainage unit position data on the same projection coordinate system as the flood inundation area to obtain a superimposed graph;

[0052] Specifically, position vector data of the city road network and drainage units is first obtained. The drainage unit refers to a drainage management unit that divides a building or a region into independent units, each of which has its own drainage system and equipment. It can be a house, an office building, a factory, a public place or a specific region of a city. Then, the road network, the drainage unit and the inundation area vector data are superimposed, that is, unified into the same coordinate system, so that the road network, the drainage unit and the inundation area are in the same coordinate system. Figure 2 In a1, a part of the superimposed graph is shown.

[0053] S400: Divide the flood inundation area based on the relative positions of the city road network, the drainage unit and the flood inundation area in the superimposed graph to obtain a flood-prone area;

[0054] Specifically, since the flood water flow follows the ups and downs of the terrain, and the same drainage unit has similar terrain features and elevation, there are only two position relationships between the drainage unit and the flood inundation area: the drainage unit is completely in the inundation area; and the drainage unit is separated from the inundation area. The obtained flood-prone area includes all flood-prone areas of the city and their areas.

[0055] S500: Calculate the distance from the flood-prone area to the surrounding emergency refuge sites, and calculate the refuge time of the flood-prone area based on the distance.

[0056] Specifically, the POI (Point of Interest) data of a city is acquired (each POI data contains the building name, address, administrative division and latitude and longitude information of the point). The coordinates of each POI in the flood-prone area or the geometric center of the flood-prone area is taken as a starting point, and the emergency shelter within a certain range is searched, and the straight-line distance from the starting point to each emergency shelter is calculated. Let n be the number of POIs in the flood-prone area, the POI number be [PO1, PO2, …POn], the emergency shelter be [B1, B2, …B n ], the distance be [L1, L2, …L n ], the emergency shelter time of each POI or geometric center starting point to each emergency shelter be [t1, t2, …t n ], the sum of the emergency shelter time of all POIs in the flood-prone area be I, and the emergency shelter time of the flood-prone area be T. Wherein, the moving speed refers to the adult jogging speed of 0.2 km / min. Then, the reciprocal of the square of the distance is taken as the weight value of the time to calculate I, that is The value of I is obtained. Finally, the average of the emergency shelter time of all POIs or geometric centers in the same flood-prone area is taken, that is The emergency shelter time T of the flood-prone area is obtained.

[0057] S600: Based on the emergency shelter time of the flood-prone area, the accessibility of the flood-prone area is evaluated.

[0058] Specifically, Figure 3 is a schematic diagram of the accessibility of the emergency shelter within a certain buffer radius range from a POI or geometric center in the flood-prone area, wherein the POI or geometric center number is [PO1], the emergency shelter is [B1, B2, B3], and the straight-line distance from the starting point to each emergency shelter is [L1, L2, L3]. Based on the emergency shelter time T of the flood-prone area calculated by S500, the accessibility of the flood-prone area is evaluated.

[0059] In this embodiment, the city DSM data is obtained because the presence of buildings and other objects in the urban environment is very important for flood research. They can affect the path and speed of water flow, and are helpful for assessing flood risk, planning drainage systems and developing emergency plans. Because the drainage unit separates the drainage pipes and equipment, it can be more effective to manage and control drainage, so using the drainage unit and road network data as one of the factors affecting the division of flood-prone areas plays an important role in flood risk analysis, flood prevention and precise measures. The distance and time from each flood-prone area to the emergency shelter are calculated to evaluate the accessibility of each flood-prone area to the shelter. This method is simple and feasible, and helps to quickly develop effective emergency plans and evacuation strategies, which has high social application value. This embodiment realizes the fine division of flood-prone areas and the accurate and efficient evaluation of the accessibility of urban flood-prone areas to emergency shelters.

[0060] In some embodiments, the flood inundation model is created based on the city DSM data and the preset flood water level, and the flood inundation area is extracted from the flood inundation model, including:

[0061] In combination with the city DSM data and the preset flood water level, a flood inundation model is created using the analysis tools in ArcGIS;

[0062] The intersection boundary of the flood surface generated according to the preset flood water level and the DSM in the model is extracted to obtain the vector range of the flood inundation area.

[0063] In specific implementation, the analysis tools in ArcGIS include Spatial Analysis or 3D Analysis. According to the vector boundary of the city in the model, the flood surface is simulated, and the low-lying areas of the city are flooded, so that the intersection boundary of the flood surface and the DSM can be further extracted, and finally the vector range of the flood inundation area is obtained, that is, a vector polygon layer is generated, each polygon represents a part of the flood inundation area, and finally the small polygons are removed and the topological errors are checked and modified to obtain the vector range of the flood inundation area.

[0064] In this embodiment, the accuracy of obtaining the range of the flood inundation area is improved.

[0065] In some embodiments, the flood inundation area is divided based on the relative positions of the city road network, the drainage unit and the flood inundation area in the overlay map to obtain the flood-prone area, including:

[0066] When the flood inundation area in the overlay map does not contain a drainage unit, the flood inundation area is divided into an independent flood-prone area;

[0067] When the flood inundation area in the superimposed graph contains a road network or a drainage unit, the flood inundation area is divided along the boundary of the road network or the drainage unit to obtain a plurality of waterlogging prone areas.

[0068] In particular implementation, as shown in Figure 2 , Figure 2 -c1 is when the flood inundation area in the superimposed graph does not contain a drainage unit, the inundation area is directly divided into an independent waterlogging prone area, as shown in Figure 2 -c2 A5. Figure 2 -a and Figure 2 -b, when the flood inundation area in the superimposed graph contains a road network or a drainage unit, first, the outer boundary of the flood inundation area is retained, and the interior of the flood inundation area is divided according to the urban road centerline and the drainage unit. Specifically, the flood inundation area is divided along the boundary of the road network or the drainage unit to obtain a plurality of waterlogging prone areas. When the polygon formed by the road and the boundary of the inundation area contains only one drainage unit, as shown in Figure 2 -a2 P3, the polygon is directly divided into a waterlogging prone area, as shown in Figure 2 -a3 A3. If the polygon contains a plurality of drainage units, as shown in Figure 2 -a2 P1 and P2, the common edges of the drainage units are extended and intersected with the road and the boundary of the inundation area, and the polygon is divided into a plurality of more detailed waterlogging prone areas, as shown in Figure 2 -a3 A1 and A2.

[0069] In this embodiment, the waterlogging prone areas are finely divided in combination with the boundaries of the urban roads and the drainage units, which helps the system to understand the spatial distribution characteristics and the influence range of the flood, and is conducive to taking appropriate flood control and disaster relief measures for waterlogging prone areas with different drainage conditions, thereby improving the accuracy of the division of the waterlogging prone areas.

[0070] In some embodiments, when the flood inundation area in the superimposed graph contains a road network or a drainage unit, the flood inundation area is divided along the boundary of the road network or the drainage unit to obtain a plurality of waterlogging prone areas, including:

[0071] When the road in the road network in the flood inundation area forms a closed area with the boundary of the flood inundation area and the closed area is next to a plurality of drainage units, the closed area is divided into a waterlogging prone area;

[0072] When the closed area is next to only one drainage unit, if the area of the closed area is smaller than the area of the drainage unit, the closed area is merged into the waterlogging prone area where the drainage unit is located.

[0073] In particular implementation, as shown in Figure 2 , Figure 2-a1, the city part road and the drainage unit are completely in the flooded area, and one of the roads forms a closed area with the boundary of the flooded area, i.e. Figure 2 -a2, the "overflow polygon". When the closed area is adjacent to multiple drainage units, such as Figure 2 -a, the "overflow polygon" is adjacent to multiple drainage units (such as Figure 2 -P2 and P3 in a2), directly dividing the "overflow polygon" into an independent waterlogging-prone area (such as Figure 2 -A4 in a3). When the closed area is only adjacent to one drainage unit, that is, the "overflow polygon" is only adjacent to one drainage unit (such as Figure 2 -P3 in b1), further comparing the area of the overflow polygon with the area of the adjacent drainage unit, if the polygon area is smaller than the drainage unit area, then the polygon is merged into the waterlogging-prone area where the adjacent drainage unit is located (such as Figure 2 -A3 in b2), that is, if the area of the closed area is smaller than the area of the drainage unit, the closed area is merged into the waterlogging-prone area where the drainage unit is located. Otherwise, the polygon is divided into an independent waterlogging-prone area (such as Figure 4 -A4 in b2).

[0074] In this embodiment, the closed area formed by the road and the boundary of the flooded area is comprehensively considered, which improves the fineness of the waterlogging-prone area division.

[0075] In some embodiments, including:

[0076] According to the data of the waterlogging-prone area, the meteorological data of the city, and the human geography data of the city, the risk level of the waterlogging-prone area is calculated.

[0077] In specific implementation, the average submerged water depth of each waterlogging-prone area is calculated according to the preset waterlogging level, the terrain height and the area of each waterlogging-prone area, and the average rainfall in the past ten years, the latest population density, the drainage system and other data of the city are obtained. In combination with the area (sorted from small to large into three levels, the top 40% of the waterlogging-prone areas is assigned a score of 1, the 40%-70% of the waterlogging-prone areas is assigned a score of 2, and the last 30% of the waterlogging-prone areas is assigned a score of 3), the average submerged water depth (as above, assigned a score of 1, 2, and 3), the rainfall (as above, assigned a score of 1, 2, and 3), the population density (as above, assigned a score of 1, 2, and 3), the drainage network load (sorted from large to small into three levels, the rest is as above, assigned a score of 1, 2, and 3), the density of rainwater inlets (sorted from large to small into three levels, the rest is as above, assigned a score of 1, 2, and 3), and whether it is at the intersection of rivers (assigned a score of 1 and 0, respectively), and other factors, different risk weights are assigned to each waterlogging-prone area, the weight scores of all factors of each waterlogging-prone area are added, and then the risk level of the waterlogging-prone area is divided based on the added scores: the total scores of each waterlogging-prone area are sorted from small to large into three levels, the top 40% of the waterlogging-prone areas is a low-risk waterlogging-prone area, the 40%-70% of the waterlogging-prone areas is a medium-risk waterlogging-prone area, and the last 30% of the waterlogging-prone areas is a high-risk waterlogging-prone area.

[0078] In this embodiment, the risk level of the waterlogging-prone area is divided in combination with the human geography attributes and meteorological environmental factors of the waterlogging-prone area, and the division result is objective, comprehensive, reasonable and effective.

[0079] In some embodiments, the calculation of the distance from the waterlogging-prone area to the surrounding emergency refuge places includes:

[0080] determining whether the waterlogging-prone area contains POIs;

[0081] if the waterlogging-prone area contains POIs, determining the coordinates of all POIs in the waterlogging-prone area;

[0082] if the waterlogging-prone area does not contain POIs, determining the coordinates of the geometric center of the waterlogging-prone area;

[0083] obtaining all emergency refuge places within a 2-kilometer buffer radius from the coordinates;

[0084] calculating the distance from the coordinates to the emergency refuge places.

[0085] In specific implementation, if the waterlogging-prone area contains multiple buildings (i.e., multiple POIs), the coordinates of each POI in the waterlogging-prone area are determined respectively; if the waterlogging-prone area does not contain buildings (i.e., there is no POI data), the geometric center coordinates of the waterlogging-prone area are calculated.

[0086] In this embodiment, when there are multiple buildings in the waterlogging-prone area, the accuracy of the accessibility evaluation is improved.

[0087] In some embodiments, the accessibility of the flood-prone area is evaluated based on the refuge time of the flood-prone area, including:

[0088] normalizing the refuge time of all the flood-prone areas to obtain a T value;

[0089] flood-prone areas with a T value of 0-0.3 are rated as having good accessibility, flood-prone areas with a T value of 0.4-0.6 are rated as having general accessibility, and flood-prone areas with a T value of 0.7-1 are rated as having poor accessibility.

[0090] In specific implementation, after obtaining the refuge time of each flood-prone area, the refuge time of a certain flood-prone area is denoted as T i , and the normalized value is T. The normalization of the refuge time of all the flood-prone areas is calculated according to the following formula: wherein T i is the refuge time of each flood-prone area, T max and T min are the maximum and minimum refuge times of the flood-prone area, respectively, and the T value ranges from 0 to 1. Further, an accessibility evaluation system of the flood-prone area is established, flood-prone areas with a T value of 0-0.3 are rated as having good accessibility, T values of 0.4-0.6 are rated as having general accessibility, and T values of 0.7-1 are rated as having poor accessibility.

[0091] In this embodiment, the rationality of constructing the accessibility evaluation system is improved.

[0092] In some embodiments, the method further includes:

[0093] combining the risk level and the accessibility of the flood-prone area to develop a flood prevention plan.

[0094] In specific implementation, for a flood-prone area with a high risk level and poor accessibility, it is suggested to increase the number of rainwater inlets, optimize the drainage pipe network, and build emergency refuge sites.

[0095] The application also provides a device for dividing and evaluating the accessibility of urban flood-prone areas, as shown in ​ , the device includes:

[0096] a flood inundation area acquisition module 101, configured to acquire urban DSM data and a preset flood water level, create a flood inundation model based on the urban DSM data and the preset flood water level, and extract a flood inundation area from the flood inundation model;

[0097] a flood-prone area division module 102, configured to superimpose urban road network position data, drainage unit position data, and the flood inundation area on the same projection coordinate system to obtain a superimposition diagram, and divide the flood inundation area based on the relative positions of the urban road network, the drainage unit, and the flood inundation area in the superimposition diagram to obtain a flood-prone area;

[0098] The reachability calculation module 103 is configured to calculate the distance from the waterlogging-prone area to the surrounding emergency refuge site, calculate the refuge time of the waterlogging-prone area based on the distance, and evaluate the reachability of the waterlogging-prone area based on the refuge time of the waterlogging-prone area.

[0099] The functions of the modules in the device for dividing and evaluating the reachability of the urban waterlogging-prone area correspond to the steps in the method for dividing and evaluating the reachability of the urban waterlogging-prone area, and the functions and implementation processes will not be described here.

[0100] The application further provides a computer readable storage medium, which stores a program, wherein the computer readable storage medium refers to a carrier for storing data, which can include, but is not limited to, a floppy disk, an optical disk, a hard disk, a flash memory, a USB flash disk, a memory stick and the like, and the computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The working process, working details and technical effects of the computer readable storage medium provided in the embodiment can be referred to the above-mentioned embodiments of the method for dividing and evaluating the reachability of the urban waterlogging-prone area, and will not be described here.

[0101] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium in the embodiments provided by the application can include non-volatile and / or volatile memory. The non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. The volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM) and memory bus dynamic RAM (RDRAM).

[0102] Any technical features in the above embodiments can be combined, and for the sake of brevity, not all possible combinations are described, however, any combination of the technical features is considered to be within the scope of the present disclosure. The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that, for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the present application, and these are all within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A method for urban waterlogging-prone area division and accessibility assessment, characterized in that, The method comprises the following steps: obtain city DSM data and preset flood water level; create a flood inundation model based on the city DSM data and the preset flood water level, and extract a flood inundation area from the flood inundation model; superimpose city road network position data and drainage unit position data on the same projection coordinate system with the flood inundation area to obtain a superimposed graph; in the superimposed graph, divide the flood inundation area based on the relative positions of the city road network, the drainage unit and the flood inundation area to obtain a waterlogging-prone area; when the flood inundation area in the superimposed graph does not contain a drainage unit, divide the flood inundation area into an independent waterlogging-prone area; when the flood inundation area in the superimposed graph contains a road network or a drainage unit, divide the flood inundation area along the boundary of the road network or the drainage unit to obtain a plurality of waterlogging-prone areas; when a road in the road network in the flood inundation area and the boundary of the flood inundation area form a closed area and the closed area is adjacent to a plurality of drainage units, divide the closed area into a waterlogging-prone area; when the closed area is adjacent to only one drainage unit, if the area of the closed area is smaller than the area of the drainage unit, merge the closed area into the waterlogging-prone area where the drainage unit is located; calculate the distance from the waterlogging-prone area to a surrounding emergency refuge site, and calculate the refuge time of the waterlogging-prone area based on the distance; evaluate the accessibility of the waterlogging-prone area based on the refuge time of the waterlogging-prone area.

2. The method of claim 1, wherein, The method comprises the following steps: combine the city DSM data and the preset flood water level, and use an analysis tool in ArcGIS to create a flood inundation model; extract the intersection boundary of the flood surface generated according to the preset flood water level and the DSM in the model to obtain the vector range of the flood inundation area.

3. The method of claim 1, wherein, The method comprises the following steps: calculate the risk level of the waterlogging-prone area according to the data of the waterlogging-prone area, the meteorological data of the city and the city human geography data.

4. The method of claim 1, wherein, The method comprises the following steps: determine whether the waterlogging-prone area contains a POI; if the waterlogging-prone area contains a POI, determine the coordinates of all POIs in the waterlogging-prone area; if the waterlogging-prone area does not contain a POI, determine the coordinates of the geometric center of the waterlogging-prone area; obtain all emergency refuge sites within a 2-kilometer buffer radius from the coordinates; calculate the distance from the coordinates to the emergency refuge sites.

5. The method of claim 4, wherein, The method comprises the following steps: normalize the refuge time of all waterlogging-prone areas to obtain a T value; evaluate the waterlogging-prone area with a T value of 0-0.3 as having good accessibility, the waterlogging-prone area with a T value of 0.4-0.6 as having general accessibility, and the waterlogging-prone area with a T value of 0.7-1 as having poor accessibility.

6. The method for urban waterlogging-prone area division and accessibility assessment according to claim 5, characterized in that, The method comprises the following steps: combine the risk level and the accessibility of the waterlogging-prone area to develop a flood prevention scheme.

7. A device for urban waterlogging-prone area division and accessibility assessment, characterized in that, The method comprises the following steps: a flood inundation area obtaining module is configured to obtain city DSM data and a preset flood water level; create a flood inundation model based on the city DSM data and the preset flood water level, and extract a flood inundation area from the flood inundation model; The waterlogging-prone area division module is configured to superimpose the urban road network position data, the drainage unit position data, and the flood inundation area in the same projection coordinate system to obtain a superimposition diagram; in the superimposition diagram, the flood inundation area is divided based on the relative positions of the urban road network, the drainage unit, and the flood inundation area to obtain a waterlogging-prone area; when the flood inundation area in the superimposition diagram does not contain a drainage unit, the flood inundation area is divided into an independent waterlogging-prone area; when the flood inundation area in the superimposition diagram contains a road network or a drainage unit, the flood inundation area is divided along the boundary of the road network or the drainage unit to obtain a plurality of waterlogging-prone areas; when a road in the road network in the flood inundation area and the boundary of the flood inundation area form a closed area and the closed area is next to a plurality of drainage units, the closed area is divided into a waterlogging-prone area; when the closed area is next to only one drainage unit, if the area of the closed area is smaller than the area of the drainage unit, the closed area is merged into the waterlogging-prone area in which the drainage unit is located; The reachability calculation module is configured to calculate the distance from the waterlogging-prone area to a surrounding emergency refuge site, and calculate the refuge time of the waterlogging-prone area based on the distance. The reachability of the waterlogging-prone area is evaluated based on the refuge time of the waterlogging-prone area.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a program, and when the program is executed by a processor, the division and reachability evaluation method of the urban waterlogging-prone area according to any one of claims 1 to 6 is implemented.

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