Infrastructure failure cascade flood disaster risk assessment method

Abstract

The invention relates to an infrastructure failure cascade flood disaster risk assessment method, which comprises the following steps of: constructing a traffic transportation network topology model of a research area, acquiring basic attributes of infrastructures in the research area, and constructing a directed graph; constructing an infrastructure system model based on the directed graph in combination with a dependency relationship among basic attributes of the infrastructure; simulating a flood condition in the research area in real time, and judging a failure road section based on a flood simulation result and the traffic transportation network topology model; based on the failed road section, the flood simulation result and the infrastructure system model, evaluating the infrastructure cascade failure condition, and obtaining the failure conditions of all infrastructures; and based on the failure conditions of all the infrastructures, evaluating the service state of the infrastructures during the flood period, and taking the service state as a risk evaluation result. Compared with the prior art, the flood risk assessment method has the advantages of more accurate and deep flood risk assessment and the like.

Description

Technical Field

[0001] The invention relates to the technical field of infrastructure risk assessment, and in particular to a method for assessing flood disaster risk of infrastructure failure cascade. Background Art

[0002] The increase in greenhouse gas emissions caused by human activities has led to an irreversible warming trend. The additional moisture produced by global warming has increased global precipitation, and floods have become more frequent. Modern society is becoming highly complex, and the interdependence between its components is increasing, especially in densely populated and industrialized urban areas. As a basic component of the city, infrastructure is both the main disaster-bearing body and the objective presenter of disaster consequences. The high degree of interdependence between them further exacerbates the spread of disaster consequences in time and space.

[0003] Risk refers to the combination of the probability of a particular hazardous event and its consequences. Risk consists of two factors: the probability of a hazardous event and the consequences of the hazardous event. At present, the assessment of urban flood risk is mostly based on the definition of system theory, such as the risk triangle theory, which includes a comprehensive representation of hazard, exposure and vulnerability. However, these flood risk assessment methods usually fail to integrate infrastructure services and their cascading effects in a structured manner.

[0004] Therefore, it is necessary to develop a flood disaster risk assessment method for infrastructure failure cascades, by analyzing the failure process of infrastructure during floods and identifying vulnerable areas of infrastructure services in the study area, so as to formulate effective disaster reduction strategies and reduce the impact of flood disasters. Summary of the invention

[0005] The purpose of the present invention is to provide a flood disaster risk assessment method for infrastructure failure cascades that accurately and deeply assesses flood disaster risk situations.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A flood disaster risk assessment method for infrastructure failure cascades includes the following steps:

[0008] Construct a transportation network topology model for the study area, obtain basic attributes of infrastructure in the study area, and construct a directed graph;

[0009] Based on the directed graph and in combination with the dependency relationship between infrastructures, an infrastructure system model is constructed;

[0010] Simulate flood conditions in the study area in real time, and determine failed sections based on the flood simulation results and the transportation network topology model;

[0011] Based on the failed road sections, flood simulation results and infrastructure system model, the infrastructure cascading failure is evaluated to obtain the failure status of all infrastructures;

[0012] Based on the failure scenarios of all the infrastructures described, the service status of the infrastructure during the flood is evaluated as the risk assessment result.

[0013] Furthermore, the basic attributes of the infrastructure include the type of infrastructure, the geographical location of the infrastructure, the failure depth threshold of the infrastructure, the real-time status of the infrastructure and the service scope of the infrastructure.

[0014] Furthermore, the infrastructure types include substations, mobile phone base stations, hospitals, fire stations, police stations, shelters and roads, wherein the substations and mobile phone base stations are infrastructure that do not rely on road transmission services, and the hospitals, fire stations, police stations and shelters are infrastructure that rely on road transmission services.

[0015] Furthermore, for the infrastructure that does not rely on road transmission services, its service range is defined by a fixed radius circular area determined by the center point of the infrastructure, wherein the infrastructure that does not rely on road transmission services and the fixed radius circular area satisfy:

[0016] S i ={∈R 2 |∥xi∥≤r}

[0017] In the formula, S i represents the set of service ranges of infrastructure i, x represents any point in the study area, i represents the location of the infrastructure, ∥xv∥ represents the Euclidean distance from point x to point c, and r refers to the service radius, i.e., a fixed radius;

[0018] For infrastructure that relies on road transmission services, the shortest path set of all reachable road network nodes within a specified distance is calculated, and a buffer zone is constructed based on the specified radius using the shortest path set, and the buffer zone is used as the service range of the infrastructure that relies on road transmission services, where the shortest path set and the specified distance satisfy:

[0019] N i = {p∈P i |dist(p)≤r}

[0020] Where N i represents the shortest path set of all accessible road network nodes within a specified distance of infrastructure i, P iIt represents the set of shortest paths from infrastructure location i to all road network nodes in the transportation network topology model. dist(p) represents the distance of the shortest path p calculated by the Dijkstra algorithm, and r represents the specified distance.

[0021] Furthermore, the vertices of the directed graph are basic attributes of infrastructure, and the edges are the relationships between infrastructure.

[0022] Furthermore, the step of constructing the infrastructure system model includes:

[0023] Based on the directed graph, the infrastructure that needs to rely on the power supply of the substation within the service range of each substation is connected to the corresponding substation using directed edges, where the set of infrastructure that relies on the power supply of the substation is expressed as:

[0024] M={(s,i)∈S×I|i∈A s}

[0025] I={H1,H2,H3,…,F1,F2,F3,…,P1,P2,P3,…,R1,R2,R3,…,C1,C2,C3,…}

[0026] S={S1,S2,S3,…}

[0027] In the formula, I represents the set of infrastructures that rely on substations for power supply, S represents the set of all substations, M represents the set of dependencies between infrastructures and substations, and A s represents the service range of a specific substation s, H1, H2, H3, ... represents a set of hospitals, F1, F2, F3, ... represents a set of fire stations, P1, P2, P3, ... represents a set of police stations, R1, R2, R3, ... represents a set of roads, and C1, C2, C3, ... represents a set of mobile phone base stations;

[0028] Based on the directed graph, the infrastructure that needs to rely on the mobile phone base station within the service range of each mobile phone base station is connected to the corresponding mobile phone base station using directed edges to obtain an infrastructure system model, in which the set of infrastructure that relies on the mobile phone base station is expressed as:

[0029] M={(c,i)∈C×I|i∈A c}

[0030] I={F1,F2,F3,…,P1,P2,P3,…}

[0031] C={C1,C2,C3,…}

[0032] In the formula, I represents the set of all fire stations and police stations, C represents the set of all mobile phone base stations, M represents the set of fire stations and police stations’ dependencies on mobile phone base stations, and Ac represents the service range of a specific mobile phone base station c, F1, F2, F3, ... represent the set of fire stations, and P1, P2, P3, ... represent the set of police stations.

[0033] Furthermore, the construction process of the transportation network topology model includes:

[0034] Acquire remote sensing images and OSM data of the study area, generate traffic section information and topological relationships between sections, wherein the traffic section information includes the length of the section and the geographical locations of the starting and ending points of the section;

[0035] Based on the traffic section information and the topological relationship between the sections, a transportation network topology model of the study area is constructed.

[0036] Furthermore, the Delft3D hydrological and hydrodynamic model was used to simulate the flooding situation in the study area in real time.

[0037] Furthermore, the step of obtaining the failure status of all infrastructures includes:

[0038] 1) Eliminate the invalid road section and update the service scope of the infrastructure that relies on road transmission services in the infrastructure system model;

[0039] 2) According to the flood simulation results and the failure water depth threshold of the infrastructure, the real-time status of the infrastructure is updated, wherein the update determination expression of the real-time status of the infrastructure is:

[0040]

[0041] In the formula, S i Represents the real-time status of the infrastructure, D i represents the water depth at the infrastructure location, T i represents the failure depth threshold of the infrastructure;

[0042] 3) Based on the updated real-time status of the infrastructure and the dependency relationship between the infrastructures in the infrastructure system model, determine whether there is a cascading failure. If so, further adjust and update the real-time status of the infrastructure according to the cascading failure evaluation results, end the evaluation of the cascading failure, and obtain the failure status of all infrastructures. If not, traverse the flood simulation results at the next moment and return to step 1) to perform the cascading failure until the end. The judgment operation expression of the cascading failure is:

[0043] F={i∈{S1,S2,S3,…,C1,C2,C3,…}|i.status∈{-1,0}}

[0044]

[0045] Where F represents the set of failed substations and mobile phone base stations, C represents the set of infrastructures that fail due to cascading, S1, S2, S3, … represent the set of substations, C1, C2, C3, … represent the set of mobile phone base stations, f is an element in the set F, c represents an element in the set of infrastructures that depend on infrastructure f, and p is an element in the set of infrastructures that infrastructure c depends on.

[0046] Further, the step of evaluating the service status of the infrastructure during the flood includes:

[0047] The study area is divided into several grid units through the rasterization method, and the service status of all infrastructure during the flood is displayed in combination with the failure conditions of all infrastructure. The service status includes normal service status, service failure status and out-of-service status.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The present invention takes infrastructure as the basic object for assessing flood risk, considers the basic attributes of infrastructure, constructs a directed graph, and constructs an infrastructure system model by considering the dependency relationship between infrastructures. This model restores the cascade relationship between infrastructures to a certain extent, providing a good basis for the subsequent assessment of cascade failures. After that, combined with the flood simulation results, it can assess the failure of all infrastructure at the location, thereby achieving an accurate and in-depth assessment of flood risk.

[0050] (2) The present invention realizes the spatial dynamic visualization of the infrastructure service status by continuously simulating flood conditions and determining the failure conditions of the infrastructure. This not only helps to detail the changes in infrastructure performance, but also makes the scope and severity of impact more intuitive.

[0051] (3) The present invention considers multiple basic attributes of infrastructure, updates the values ​​of basic attributes through the dependencies between infrastructure and flood simulation results, and thus evaluates the flood disaster risk of infrastructure. The present invention considers the basic attributes of infrastructure more comprehensively, reflects the status of infrastructure during floods through changes in basic attribute values, and can more effectively implement risk assessment. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0053] Figure 2 It is a schematic diagram of the infrastructure system model of the present invention;

[0054] Figure 3It is a flow chart of infrastructure failure determination of the present invention;

[0055] Figure 4 It is a visualization diagram of the substation service status space at the end of the present invention;

[0056] Figure 5 This is a visualization diagram of the mobile phone base station service status space at the end of the present invention;

[0057] Figure 6 It is a visualization diagram of the hospital service status space at the end of the present invention;

[0058] Figure 7 It is a visualization diagram of the fire station service status space at the end of the present invention;

[0059] Figure 8 It is a visualization diagram of the police station service status space at the end of the present invention;

[0060] Fig. 9 This is a visualization diagram of the state space of the shelter service at the end of the present invention. DETAILED DESCRIPTION

[0061] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0062] This embodiment provides a flood disaster risk assessment method for infrastructure failure cascades, such as Figure 1 As shown, the method comprises the following steps:

[0063] Step 1: Determine the basic attributes of infrastructure.

[0064] First, a directed graph object G is created using the complex network analysis tool NetworkX, whose nodes represent all infrastructures. Each node is assigned a 'label' attribute, which is the infrastructure type, specifically set as follows: substations are marked as 'Substation', cell towers are 'Celltower', hospitals are 'Hospital', fire stations are 'Fire', police stations are 'Police', shelters are 'Shelter', and roads are 'Road'. Next, the longitude and latitude coordinates of each infrastructure are recorded in the 'pos' attribute. After that, according to the "Hazus Asset Inventory Technical Guide" issued by the Federal Emergency Management Agency, a failure water depth threshold 'threshold' is set for each facility type, which is specifically set as follows: 1.2m for substations, 0.2m for cell towers, 0.15m for hospitals and shelters, 0.3m for police stations, 0.6m for fire stations, and 1m for roads. In addition, each infrastructure is set with a real-time status attribute 'status', where status 1 indicates normal operation, status 0 indicates that the infrastructure has directly failed due to flood depth exceeding the failure depth threshold, and status -1 indicates that the infrastructure has indirectly failed due to cascading effects. Finally, the service range of each infrastructure is recorded through the 'geometry' attribute. For facilities such as substations and mobile phone base stations that do not rely on road transmission services, their service range is defined by a fixed radius circular area determined by the center point of the facility:

[0065] S i = {x∈R 2 |∥xi∥≤r}

[0066] In the formula, x represents any point in the study area, i represents the location of the infrastructure, and S i represents the set of service ranges of infrastructure i, ∥xc∥ represents the Euclidean distance from point x to point c, and r refers to the service radius. According to information from a certain city power supply bureau, the power supply radius of the substation is set to 1.5 km, because the power quality will decrease beyond this range, resulting in voltage instability. In addition, during a typhoon in 2018, the communication in the area basically relied on the 4G network. Telecom operators pointed out that although the standard coverage radius of 4G base stations is 1 to 3 km, in order to highlight the damage that may be caused by floods and identify potential communication failure areas in the study area, the service radius of all mobile base stations was uniformly set to 1 km.

[0067] For infrastructure types that rely on roads for service delivery (hospitals, fire stations, police stations, shelters), the Dijkstra algorithm is used to calculate the shortest path to other road network nodes starting from a specific infrastructure location (only calculating road network nodes within a specified distance from the starting infrastructure location). The calculation result can be expressed as the following set:

[0068] N i = {p∈P i |dist(p)≤r}

[0069] Where P i represents the shortest path set from infrastructure location i to all road network nodes in the transportation network topology model, N i represents the shortest path set of all accessible road network nodes within the specified distance of infrastructure i, dist(p) represents the distance of the shortest path p, and r represents the specified distance. According to Article 81 of the Regulations for the Implementation of the Road Traffic Safety Law, when a motor vehicle encounters low visibility weather with visibility less than 50m on a highway, all lights should be turned on, the speed should not exceed 20km / h, and the highway should be driven off as soon as possible. At the same time, referring to the concept of "15min living circle" proposed by a certain city, for infrastructure whose service transmission depends on roads, we set its service range to 5km.

[0070] The above shortest path set is used to construct a buffer zone based on the specified radius as the service range of the infrastructure. We set the maximum walking time for residents to the nearest road to 10 minutes, and based on the average walking speed of 1.37m / s, the service radius of the corresponding road is set to 820m.

[0071] Step 2: Construction of infrastructure system model.

[0072] The schematic diagram of the infrastructure system model is as follows: Figure 2 As shown in Figure 1, for each substation, the relevant infrastructure (hospitals, fire stations, police stations, shelters, and mobile phone base stations) within its service range are connected to the substation, and these connections are used as directed edges E d Added to the directed graph object G, the modeling logic is as follows:

[0073] I={H1,H2,H3,…,F1,F2,F3,…,P1,P2,P3,…,R1,R2,C3,…,C1,C2,C3,…}

[0074] S={S1,S2,S3,…}

[0075] M={(s,i)∈S×I|i∈A s}

[0076] In the formula, I represents the set of infrastructures that rely on substations for power supply, S represents the set of all substations, M represents the set of dependencies between infrastructures and substations, and A s Represents the service area of ​​a specific substation s;

[0077] For each mobile phone base station, connect the fire stations and police stations within its service range to the mobile phone base station and use these connections as directed edges E d Added to the directed graph object G, the modeling logic is as follows:

[0078] I={F1,F2,F3,…,P1,P2,P3,…}

[0079] C={C1,C2,C3,…}

[0080] M={(c,i)∈C×I|i∈A c}

[0081] In the formula, I represents the set of all fire stations and police stations, C represents the set of all mobile phone base stations, M represents the set of fire stations and police stations’ dependencies on mobile phone base stations, and A c Represents the service range of a specific mobile base station c.

[0082] Step 3: Determine the infrastructure failure process.

[0083] Specifically, remote sensing images and OSM (Open Street Map) data are used to generate traffic section information, including the length of the section, the geographical location of the starting and ending points of the section, and the topological relationship between the sections, to generate a topological model of the transportation network in the study area.

[0084] The overall flow chart is as follows Figure 3 As shown:

[0085] According to the flood simulation results combined with the transportation network topology model, the affected road sections are analyzed, the sections with flood depth exceeding 1m are eliminated, and the service area of ​​the infrastructure that relies on road transmission services is recalculated. According to the flood simulation results combined with the infrastructure failure depth threshold, the real-time status attribute "status" of the infrastructure is updated, and the judgment logic is as follows:

[0086]

[0087] In the formula, S i Represents the real-time status of the infrastructure, D i represents the water depth at the infrastructure location, T i Represents the failure depth threshold of the infrastructure.

[0088] Based on the real-time status of the above infrastructure and the dependencies between the infrastructure in the directed graph G, the assessment shows the possibility of cascading failure. Based on the assessment results, the real-time status attribute "status" of each infrastructure is further adjusted and updated. The specific judgment logic is as follows:

[0089] F={i∈{S1,S2,S3,…,C1,C2,C3,…}|i.status∈{-1,0}}

[0090]

[0091] Where F represents the set of failed substations and mobile phone base stations, and C represents the set of infrastructure that fails due to the cascade.

[0092] Traverse the flood simulation results of the next moment. If there are results, return and execute the first step. If not, end the process.

[0093] Step 4: Verify the infrastructure service failure area.

[0094] Combined with the failure process of infrastructure during floods, the three service states in the study area are displayed through a rasterization method: normal service state, service failure state and out-of-service area. For infrastructure that relies on road transmission services, the normal service area refers to the area that can be reached within 15 minutes by car; the service failure area refers to the area that takes more than 15 minutes to reach by car; the out-of-service area refers to places that cannot be reached by car, such as hills, reservoirs, etc.

[0095] Verify the results by using the failure or validity points mentioned in the news reports. Figures 4 to 9 The substations are shown respectively. Figure 4 )、Mobile base stations( Figure 5 ),Hospital( Figure 6 )、Fire Station( Figure 7 )、Police Station( Figure 8 ) and Shelters ( Fig. 9 )’s service status space visualization (final moment). Among these facilities, verification has been completed for substations, hospitals, fire stations, and police stations. Specifically, verification of substations was performed based on power failure location points, while verification of hospitals, fire stations, and police stations was completed based on valid points. The accuracy of the evaluation results was ensured by combining the results with the failure or valid location points recorded in the news reports.

[0096] By simulating the hourly failure process of infrastructure, we can achieve a spatial dynamic visualization of the infrastructure service status. This method not only helps us understand the changes in infrastructure performance every hour in detail, but also makes the scope and severity of impact more intuitive.

[0097] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

[0098] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0099] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0100] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0101] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0102] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other 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.

[0103] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A flood disaster risk assessment method for infrastructure failure cascades, characterized in that: The following steps are involved: Construct a transportation network topology model for the study area, obtain basic attributes of infrastructure in the study area, and construct a directed graph; Based on the directed graph and in combination with the dependency relationship between infrastructures, an infrastructure system model is constructed; Simulate flood conditions in the study area in real time, and determine failed sections based on the flood simulation results and the transportation network topology model; Based on the failed road sections, flood simulation results and infrastructure system model, the infrastructure cascading failure is evaluated to obtain the failure status of all infrastructures; Based on the failure scenarios of all the infrastructures described, the service status of the infrastructure during the flood is evaluated as the risk assessment result.

2. The method for assessing flood disaster risk of infrastructure failure cascade according to claim 1, characterized in that: The basic attributes of the infrastructure include the type of infrastructure, the geographical location of the infrastructure, the failure depth threshold of the infrastructure, the real-time status of the infrastructure and the service scope of the infrastructure.

3. The method for assessing flood disaster risk of infrastructure failure cascade according to claim 2, characterized in that: The infrastructure types include substations, mobile phone base stations, hospitals, fire stations, police stations, shelters and roads, among which the substations and mobile phone base stations are infrastructure that do not rely on road transmission services, and the hospitals, fire stations, police stations and shelters are infrastructure that rely on road transmission services.

4. The method for assessing flood disaster risk of infrastructure failure cascade according to claim 3, characterized in that: For the infrastructure that does not rely on road transmission services, its service range is defined by a fixed radius circular area determined by the center point of the infrastructure, wherein the infrastructure that does not rely on road transmission services and the fixed radius circular area satisfy: S i ={x∈R 2 |∥x-i∥≤r} In the formula, S i represents the set of service ranges of infrastructure i, x represents any point in the study area, i represents the location of the infrastructure, ∥xc∥ represents the Euclidean distance from point x to point c, and r refers to the service radius, i.e., a fixed radius; For infrastructure that relies on road transmission services, the shortest path set of all reachable road network nodes within a specified distance is calculated, and a buffer zone is constructed based on the specified radius using the shortest path set, and the buffer zone is used as the service range of the infrastructure that relies on road transmission services, where the shortest path set and the specified distance satisfy: N i ={p∈P i |dist(p)≤r} Where N i represents the shortest path set of all accessible road network nodes within a specified distance of infrastructure i, P i It represents the set of shortest paths from infrastructure location i to all road network nodes in the transportation network topology model. dist(p) represents the distance of the shortest path p calculated by the Dijkstra algorithm, and r represents the specified distance.

5. The method for assessing flood disaster risk of infrastructure failure cascade according to claim 1, characterized in that: The vertices of the directed graph are basic attributes of infrastructure, and the edges are the relationships between infrastructure.

6. The method for assessing flood disaster risk of infrastructure failure cascade according to claim 1, characterized in that: The steps of constructing the infrastructure system model include: Based on the directed graph, the infrastructure that needs to rely on the power supply of the substation within the service range of each substation is connected to the corresponding substation using directed edges, where the set of infrastructure that relies on the power supply of the substation is expressed as: M={(s,i)∈S×I|i∈A s } I={H1,H2,H3,…,F1,F2,F3,…,P1,P2,P3,…,R1,R2,R3,…,C1,C2,C3,…} S={S1,S2,S3,…} In the formula, I represents the set of infrastructures that rely on substations for power supply, S represents the set of all substations, M represents the set of dependencies between infrastructures and substations, and A s represents the service range of a specific substation s, H1, H2, H3, ... represents a set of hospitals, F1, F2, F3, ... represents a set of fire stations, P1, P2, P3, ... represents a set of police stations, R1, R2, R3, ... represents a set of roads, and C1, C2, C3, ... represents a set of mobile phone base stations; Based on the directed graph, the infrastructure that needs to rely on the mobile phone base station within the service range of each mobile phone base station is connected to the corresponding mobile phone base station using directed edges to obtain an infrastructure system model, in which the set of infrastructure that relies on the mobile phone base station is expressed as: M={(c,i)∈C×I|i∈A c } I={F1,F2,F3,…,P1,P2,P3,…} C={C1,C2,C3,…} In the formula, I represents the set of all fire stations and police stations, C represents the set of all mobile phone base stations, M represents the set of fire stations and police stations’ dependencies on mobile phone base stations, and A c represents the service range of a specific mobile phone base station c, F1, F2, F3, ... represent the set of fire stations, and P1, P2, P3, ... represent the set of police stations.

7. The method for assessing flood disaster risk due to infrastructure failure cascade according to claim 1, characterized in that: The construction process of the transportation network topology model includes: Acquire remote sensing images and OSM data of the study area, generate traffic section information and topological relationships between sections, wherein the traffic section information includes the length of the section and the geographical locations of the starting and ending points of the section; Based on the traffic section information and the topological relationship between the sections, a transportation network topology model of the study area is constructed.

8. The method for assessing flood disaster risk due to infrastructure failure cascade according to claim 1, characterized in that: The Delft3D hydrological and hydrodynamic model is used to simulate the flood conditions in the study area in real time.

9. The method for assessing flood disaster risk of infrastructure failure cascade according to claim 1, characterized in that: The steps of obtaining the failure conditions of all infrastructures include: 1) Eliminate the invalid road section and update the service scope of the infrastructure that relies on road transmission services in the infrastructure system model; 2) According to the flood simulation results and the failure water depth threshold of the infrastructure, the real-time status of the infrastructure is updated, wherein the update determination expression of the real-time status of the infrastructure is: In the formula, S i Represents the real-time status of the infrastructure, D i represents the water depth at the infrastructure location, T i represents the failure depth threshold of the infrastructure; 3) Based on the updated real-time status of the infrastructure and the dependency relationship between the infrastructures in the infrastructure system model, determine whether there is a cascading failure. If so, further adjust and update the real-time status of the infrastructure according to the cascading failure evaluation results, end the evaluation of the cascading failure, and obtain the failure status of all infrastructures. If not, traverse the flood simulation results at the next moment and return to step 1) to perform the cascading failure until the end. The judgment operation expression of the cascading failure is: F={i∈{S1,S2,S3,…,C1,C2,C3,…}|i.status∈{-1,0}} Where F represents the set of failed substations and mobile phone base stations, C represents the set of infrastructures that fail due to cascading, S1, S2, S3, … represent the set of substations, C1, C2, C3, … represent the set of mobile phone base stations, f is an element in the set F, c represents an element in the set of infrastructures that depend on infrastructure f, and p is an element in the set of infrastructures that infrastructure c depends on.

10. The method for assessing flood disaster risk of infrastructure failure cascade according to claim 1, characterized in that: The steps for assessing the service status of infrastructure during a flood include: The study area is divided into several grid units through the rasterization method, and the service status of all infrastructure during the flood is displayed in combination with the failure conditions of all infrastructure. The service status includes normal service status, service failure status and out-of-service status.

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