JP2008084243A - Flood simulation device and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a detailed flood depth distribution from a simulation result obtained with a rough grid. <P>SOLUTION: By this flood simulation program for making a computer, which has a storage device storing topographic data based on a first grid and a computing part, execute a flood simulation, interpolation by water depth is carried out for a part of rapid flow based on a rough flood depth distribution and a rough flow rate distribution calculated by the flood simulation, while interpolation by water level is carried out for a part of tranquil flow, and finally, conversion to the detailed flood depth distribution is carried out. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a prediction / analysis apparatus for flooding that causes flood damage. In particular, the present invention relates to an inundation simulation apparatus that simulates a process of flowing river water from a river into an urban area using a computer and displays the resulting inundation depth on a display.

  In recent years, flood damage due to torrential rains and typhoons has frequently occurred, and effective measures to reduce the damage have been demanded. In order to reduce damage, it is necessary to know in advance the possible flood damage. Against this background, an “inundation simulation device” has been proposed. Examples thereof include a real-time dynamic inundation simulation system disclosed in JP 2004-197554 (Patent Document 1) and a simplified flood inundation analysis system disclosed in JP 2005-128838 (Patent Document 2). When a point where the embankment breaks is input to this device, a map with the inundation depth distribution is output. This map serves as a scientific basis for determining the evacuation target area at the time of a breach, for example. Therefore, it is considered that the inundation simulation device can be applied to regional disaster prevention work of administrative agencies such as local governments, and further to damage risk evaluation work of non-life insurance companies.

  An inundation simulation device is required to output a detailed (high spatial density) inundation depth distribution from the characteristics of its use. For this purpose, a fine grid may be used in the simulation and the grid interval may be reduced. However, in order to actually use a fine grid in the simulation, it is necessary to solve two problems. The first issue is the measurement of topography, and the second issue is to secure computational resources.

  Regarding the first problem, it has been unrealistic from the viewpoint of cost to measure the topography with a small lattice spacing. In recent years, a technology called aviation laser measurement has been developed, and it has become possible to measure the ground surface with a lattice spacing one or two orders of magnitude smaller than before. It can be said that the first problem is being solved.

  However, there is still no definitive solution for the second issue. Inundation simulation using a fine grid requires enormous computational resources. Therefore, the flood simulation is limited to users who can secure computing resources (for example, users who have sufficient time to wait for simulation results for a long time, or users who have a supercomputer). A user who has only the computational resources of a personal computer (PC), and who does not have enough time to wait for a simulation result, still performs a simulation using a coarse grid.

  Recently, a technology for converting simulation results using a coarse grid into detailed data using detailed topographic data that has become newly measurable has been developed. As an example thereof, there is a “feature occupancy measurement method according to altitude and an inundation depth correction method using the same” described in JP-A-2005-172634 (Patent Document 3). This document describes a method for calculating feature occupancy from high-density elevation data and a method for improving simulation accuracy from the feature occupancy in order to accurately grasp the behavior of inundation flow in dense urban areas such as urban areas. Is disclosed. In this method, first, the altitude data in the grid is separated into either “ground” or “feature”. Next, the feature occupation ratio r at an altitude h is calculated as r (h) = n (h) / N. Here, N is the total number of elevation data points in the grid, and n (h) is the number of elevation data points of the “feature” at a certain elevation h. Furthermore, the water level h obtained by the flood simulation is corrected using this r (h). According to this method, the accuracy of simulation results can be improved in urban areas where the features have a great influence on the flood flow.

  Alternatively, techniques for generating realistic computer graphics using simulation results have been developed. As an example thereof, “a method for creating a three-dimensional moving image of a fluid and its program” described in Japanese Patent No. 3748268 (Patent Document 4) can be cited. In this document, a method of outputting a three-dimensional spatial image of a fluid spreading on the ground is disclosed. In this method, first, a text file storing simulation results is read. Next, a flag is set at a point where the water depth has changed. Finally, the water depth at the point where this flag is set is changed over time. According to this method, a three-dimensional moving image can be created from a text file storing simulation results.

JP2004-197554 JP2005-128838 JP 2005-172634 Patent No. 3748268 Japanese Patent Application No. 2006-81881 Japanese Patent Application No. 2005-212458 Satoshi Kurishiro, Tadaji Suetsuji, Hitoshi Unno, Yoshito Tanaka, Hiroaki Kobayashi: Inundation Simulation Manual (Draft), Civil Engineering Research Institute Material 3400, 1996.

  However, the grid of the inundation depth data obtained by the method of Patent Document 3 is coarse because it is the same grid as the flood simulation. Also in the method of Patent Document 4, when a coarse grid is used in the simulation, it is visualized as a coarse grid.

  This invention is made | formed in view of the subject mentioned above, and it aims at producing | generating a detailed inundation depth distribution from the simulation result obtained by a coarse lattice.

An inundation simulation program for executing an inundation simulation in a computing device having at least a storage device for storing terrain data by a first grid and an arithmetic unit,
In the calculation unit,
A first step of performing hydraulic calculation using a second grid having a different arrangement from the first grid using topographic data read from the storage device, and outputting at least water depth data and water level data from the second grid When,
Using the water depth data or water level data by the second grid and the topographic data by the first grid, the water depth data or the water level by the first grid by spatially interpolating the water depth data or the water level data by the second grid. A flood simulation program characterized in that the second step of outputting as inundation data by data is executed.

  According to the present invention, a detailed inundation depth distribution can be generated from a flood simulation result using a coarse grid.

  As described above, an object of the present invention is to generate a detailed inundation depth distribution from simulation results obtained with a coarse lattice. First, the inventors paid attention to the lattice spacing of terrain data with high spatial density that has been practically used in recent years. For example, the grid interval of “Numeric Map 5m Mesh Elevation” published by the Geospatial Information Authority of Japan is 5 m. On the other hand, the lattice spacing of flood simulation is generally 250m to 500m. For example, in order to create a flood inundation area map for 134 rivers in 107 rivers nationwide, inundation simulation with a grid interval of 250 m in 65 rivers (45%) and a grid interval of 500 m in 68 rivers (48%) has been adopted. (Satoshi Kurishiro, Tadaji Suetsuji, Hitoshi Unno, Yoshito Tanaka, Hiroaki Kobayashi: Inundation Simulation Manual (Draft), Civil Engineering Research Institute Material No. 3400, 1996 (Non-patent Document 1)). That is, it can be said that the grid interval of topographic data with high spatial density that has been practically used in recent years is smaller than the grid interval of general flood simulation. Therefore, the inventors examined a method of interpolating the rough inundation depth distribution calculated by the inundation simulation using fine topographic data and finally converting it to a fine inundation depth distribution. However, when a general interpolation method is used, an unnatural water surface shape is intuitively generated. Furthermore, when 3D CG was generated using this water surface shape, an unnatural landscape was generated intuitively. This is probably because the laws of physics are ignored during interpolation of the water surface.

  Therefore, the inventors examined an interpolation method according to the physical law. The inventors focused on the fact that there are a water level and a water depth as elements constituting the water surface shape, and both follow different physical laws. The water level is the elevation of the water surface, and the water depth is the distance between the water surface and the ground surface. From the theory of specific head in hydraulics, the water level is slower than the water depth when the flow is slow (normal flow, subcritical flow), and the water depth is spatially slower than the water level when the flow is fast (supercritical flow). It can be seen that there is a tendency to change.

  The inventors have conceived a method of achieving the above-described object by simultaneously using the physical laws relating to this flow and the above-mentioned property of the topographic data. In other words, from the rough inundation depth distribution and the rough flow velocity distribution calculated by the inundation simulation, the flow is interpolated by the water depth, the normal flow is interpolated by the water level, and finally converted into a fine inundation depth distribution. is there. By this method, a fine inundation depth distribution can be easily generated. This method can be used, for example, for detailed inundation damage estimation or 3D CG generation of flooded cityscapes.

  Hereinafter, an embodiment of the flood simulation program of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic block diagram showing the configuration of a computer system for realizing the present invention in this embodiment. A user of the flood simulation apparatus inputs a command from an input unit such as a keyboard 111 and a mouse 112 connected to a PC (Personal Computer) 100, and confirms the execution result of the command from an output unit such as a display 113. Inside the PC 100, a CPU (Central Processing Unit) 140 executes instructions based on the flood simulation program 131 and the geographic information management program 132 developed in the memory 130. The flood simulation program 131 reads the scenario file 121 stored in the external storage device 120 such as a hard disk and writes the inundation depth file 123 as necessary. The geographic information management program 132 reads the terrain file 122, the inundation depth file 123, and the geographic information file 124 stored in the external storage device 120 as necessary. The geographic information is data composed of values associated with a space such as a station and a feature name.

  FIG. 2 is a diagram showing a main GUI (Graphical User Interface) of the geographic information management program 132. As shown in FIG. The GUI includes a window 200 displayed in a predetermined area of the display 113. A map 210 is displayed in the window 200, and the user can enlarge or reduce the scale of the map 210 by appropriately operating the keyboard 111 or the mouse 112, or the display range can be moved to the east, west, south, and north. This map only needs to be contents to visually indicate the position of the real space to the user. As a specific example, map 210 shows a case where 3D CG (computer graphics) is displayed. This 3D CG includes the ground surface generated from the terrain file 122, textures generated from high-resolution satellite images, 3D shapes such as the station building 211 generated from 3D CAD (computer-aided design) data, and feature name data Text such as the feature name 212 generated from the map, a track generated from the vector map data, and a polyline such as the river channel normal 213 are arranged. The geographic information such as satellite images is stored in advance in the external storage medium 120 as the geographic information file 124.

  The window 200 has a menu bar 202 that receives input from the keyboard 111 and the mouse 112. Through the menu bar 202, the user first selects “set” to set a scenario, and then selects “execute” to start the simulation. The scenario is a boundary condition of the simulation, for example, a bank breakage position and an inflow amount time series from that position. Such information may be read from the scenario file 121 stored in advance in the external storage medium 120 or may be created by the user. In the latter case, the user may select one point of the map 210 as the bank breakage position with the mouse pointer 201 that moves in conjunction with the mouse 112. Or you may utilize the technique regarding the "flooding simulation apparatus and program" described in Japanese Patent Application No. 2006-81881 (patent document 5). At this time, it is desirable to display an icon 221 indicating the bank breakage position on the map 210 for the convenience of the user. When the user selects “execute” from the menu bar 202 after setting the scenario, the simulation starts. Specifically, the geographic information management program 132 requests the flood simulation program 131 to start. The flood simulation program 131 that has received the start request acquires information necessary for the simulation from the geographic information management program 132 and passes the simulation result to the geographic information management program 132 at a predetermined timing. Upon receiving the result, the geographic information management program 132 displays the information as a flooded area 222 on the map 210. The flooded area 222 is made up of polygons that display colors corresponding to the flooded depth for each grid. Further, it is stored in the external storage medium 120 as the inundation depth file 123 as necessary.

  The status bar 204 of the window 200 displays “interpolation on” when the interpolation function of the present invention is valid, and “interpolation off” when it is invalid. This interpolation function is switched between valid and invalid by appropriate operation by the user. FIG. 2 shows a state where the interpolation function is disabled. In this case, the three-dimensional CG displayed as the map 210 and the flooded area 222 are expressed by the same grid as the calculation grid.

  FIG. 3 is a diagram showing a GUI when the interpolation function is valid. When the interpolation function is effective, the three-dimensional CG displayed as the map 210 and the flooded area are expressed by a predetermined grid. For example, the flooded area 222 is represented by the same grid as the calculation grid, while the flooded area 322 is represented by a display grid having a higher spatial density (hereinafter referred to as a display grid).

  FIG. 4 is a diagram showing a water level section display window when the interpolation function is disabled. When the user creates a straight line 203 by appropriately operating the mouse pointer 201 on the map 210 of the window 200, a window 400 representing a water level sectional view along the straight line 203 is displayed in a predetermined area of the display 113. Reference numeral 411 denotes a water surface, 412 denotes a ground surface, and 413 denotes a calculation grid. The water surface 411 and the ground surface 412 are represented by the same grid as the calculation grid 413. The ground surface 412 may be displayed by processing terrain data managed by a finer grid and matching it with a calculation grid, or using terrain data matched with a calculation grid prepared in advance.

  FIG. 5 is a diagram showing a water level section display window when the interpolation function is effective. As in FIG. 4, the water surface 511 and the ground surface 512 are expressed in a lattice pattern, but the fineness of the lattice is different between FIG. 4 and FIG. In FIG. 4, the water surface and the ground surface represented by the calculation grid 413 are displayed by the display grid 513 in FIG.

  Hereinafter, processing for generating the information on the inundation depth shown in FIGS. 2 to 5 will be described. Specifically, a process performed after the user selects “execute” from the menu bar 202 until the information on the inundation depth is displayed in the window 200 or 400 will be described. As described above, when the user selects the “execute” menu after setting the scenario, the geographic information management program 132 requests the flood simulation program 131 to start. The flood simulation program 131 that has received the start request acquires information necessary for the simulation from the geographic information management program 132 and passes the simulation result to the geographic information management program 132 at a predetermined timing.

  FIG. 6 is a PAD (Problem Analysis Diagram) diagram regarding the flood simulation processing of the flood simulation program 131.

  In step 601, terrain data is acquired. Specifically, the flood simulation program 131 requests topographic data from the geographic information management program 132. Upon receiving the request, the geographic information management program 132 reads the terrain data stored as the terrain data file 122 and passes it to the inundation simulation program 131. It is assumed that the terrain data is resampling in a grid at the time of delivery. In the following, for the sake of simplicity in this embodiment, the three origins of the topographic data grid, calculation grid, and display grid have the same origin, the x-axis positive direction is east, and the y-axis positive direction is north. It is assumed that is a square. The grid interval of topographic data is dxdata, the calculation grid interval is dxsim, and the display grid interval is dxvis. However, the present invention is not limited to a square lattice, and can be applied to both a structured grid and an unstructured grid, and further, a simulation such as an adaptive mesh. It will be apparent from the following description that the present invention can be applied to a lattice that changes during execution.

  In step 602, the terrain data is downsampled. Downsampling is a process that increases the sampling interval of data, that is, decreases the sampling rate, and is generally realized by a low-pass filter in audio processing and image processing. ing. Here, downsampling is realized by the same processing. Specifically, if the grid interval dxdata of the terrain data is much smaller than the calculation grid interval dxsim (dxdata << dxsim), the terrain data is two-dimensionally smoothed with the size dxsim / dxdata, and the nearest neighbor method (Nearest Neighbor method) Resample with. When dxdata is about the same as dxsim (dxdata to dxsim), resampling is performed by the nearest neighbor method without smoothing. Here, downsampling is performed, but a method of preparing topographic data of the density of the calculation grid in advance for hydraulic calculation is also within the scope of the present invention.

  In step 603, hydraulic calculation is performed. As for the specific method of hydraulic calculation, Satoshi Kurishiro, Tadaji Suetsuji, Hitoshi Unno, Yoshito Tanaka, Hiroaki Kobayashi: Inundation Simulation Manual (draft), Civil Engineering Research Institute Material No. 3400, 1996. (Non-patent Document 1) Refer to the implementation. Alternatively, a technique related to “space simulation method and apparatus” described in Japanese Patent Application No. 2005-212458 (Patent Document 6) may be used. Hereinafter, in the present embodiment, a case will be described in which a shallow water equations differentiated by a staggered grid is solved as a hydraulic calculation.

  FIG. 7 is a diagram showing the calculation grid and variable arrangement of this embodiment. As described above, the lattice is a square of one side dxsim with the east as the x-axis positive direction and the north as the y-axis positive direction. Where Dw: depth of water, Lw: water level (Lw = Dw + Lg, Lg: elevation of the ground surface), q: lateral inflow, u, v: velocity in the x-axis and y-axis directions, M, N: units The width flow rate (M = u * Dw, N = v * Dw). Because of the staggered grid, the positions 702 of the variables Mi, j, ui, j are shifted by −dxsim / 2 from the positions 701 of Dwi, j, Lwi, j, qi, j. Similarly, the positions 703 of Ni, j, vi, j are arranged with a shift of −dxsim / 2 with respect to the position 701, respectively. As a result of the hydraulic calculation in step 603, the values of these variables are obtained.

  In step 604, a jet flag is calculated. Here, the jet which is the concept of hydraulics will be described. FIG. 8 is a diagram for explaining the difference in water surface shape between normal flow and jet flow. It is known that the water flow is large and can be classified into subcritical flow, critical flow or supercritical flow. In the portion 803 where the slope of the ground surface is gentle, the flow of water is generally normal, and at this time, the water level changes spatially more gently than the water depth. On the other hand, at the point 801 where the slope of the ground surface is steep, the flow of water is a limit flow or a jet flow, and at this time, the water depth changes spatially gently compared to the water level. As the spatial variation of the physical quantity is more gradual, more accurate interpolation can be expected. Therefore, the distinction between normal flow and jet for each grid is stored as a jet flag fxi, j, fyi, j, and interpolation is performed based on this flag at the time of interpolation. Set the flag to true for shooting and false for normal flow.

In the theory of hydraulics, normal flow, limit flow, and jet can be distinguished by the following formulas.
U <c: Normal
U = c: critical flow
U> c: supercharge, where U: velocity of flow, c: gravity wave velocity (c = sqrt (grav * Dw), sqrt (): function returning square root, grav: gravity acceleration = 9.81 m / sec2). Applying this theory, for example, in the case of a staggered grid, the normal flow and the superficial flow may be discriminated by the following equations.
fxi, j = abs (ui, j)> sqrt (grav * (Dwi-1, j + Dwi, j) / 2)
fyi, j = abs (vi, j)> sqrt (grav * (Dwi, j-1 + Dwi, j) / 2)
However, A> B: An operator that returns true when A> B, false otherwise, abs (): A function that returns an absolute value. It should be noted that a turbulent phenomenon called hydraulic jump is prominent at the point 802 where the flow changes from a normal flow to a normal flow. In order to avoid the complexity of flow in this jump, some hydraulic calculation methods distinguish normal flow and jet from only the water level, and in the case of jet, approximate the flow velocity by the gravity wave velocity c. In this case, the normal flow and the jet flow may be discriminated by the following expression, for example.
fxi, j = ((Lwi-1, j> Lwi, j) and (Dwi-1, j> 0) and (Lgi-1, j> Lwi, j))
or ((Lwi, j> Lwi-1, j) and (Dwi, j> 0) and (Lgi, j> Lwi-1, j))
fyi, j = ((Lwi, j-1> Lwi, j) and (Dwi, j-1> 0) and (Lgi, j-1> Lwi, j))
or ((Lwi, j> Lwi, j-1) and (Dwi, j> 0) and (Lgi, j> Lwi, j-1))
However, A and B: An operator that returns true when A and B are true, otherwise false, A or B: An operator that returns true when A or B is true, and false otherwise.

  Returning to FIG. 6, description will be continued. If the interpolation function is valid, an interpolation calculation using the water depth and / or water level obtained by the hydraulic calculation is performed in step 605. As described above, the interpolation function is switched between valid / invalid when the user appropriately operates, and whether the interpolation function is valid / invalid is described in the status bar 204 of the window 200. In step 605, upsampling of the inundation depth is performed. Up-sampling is processing for reducing the sampling interval of data, that is, increasing the sampling rate, and interpolation processing is generally performed in audio processing and image processing. Here, an interpolation process using hydraulics is performed.

  Details of the processing in step 605 are shown in FIG. FIG. 9 is a PAD diagram relating to interpolation processing applying hydraulics. In step 901, the processing from step 902 to step 906 is repeated for all display grids.

  In step 902, the display grid is converted to a calculation grid. This can be done by using a normal two-dimensional coordinate transformation. By this coordinate transformation, the display grid (P, Q) becomes the calculation grid (p, q). However, P and Q take integer values, and p and q take real values.

  In step 903, the flow state is discriminated by the lattice (p, q) using the jet flags fxi, j, fyi, j. This can be done by referring to the nearest jet flag of the grid (p, q).

  If step 903 is false, that is, if it is normal flow, steps 904 and 905 are executed. In step 904, the water level value at the point (p, q) is obtained by interpolation. For the interpolation, bilinear interpolation or the like may be used. In step 905, the water level value is converted into a water depth value. For this, a relational expression (Dw = Lw−Lg) between the water depth Dw and the water level Lw is used. However, as the elevation Lg of the ground surface at the point (p, q), a value stored in the topographic data file 122 as the elevation of the ground surface in the grid (P, Q) may be used.

  If step 903 is true, that is, if it is a jet, step 906 is executed. In step 906, the water depth value at the point (p, q) is obtained by interpolation. As in step 904, bilinear interpolation or the like may be used for interpolation.

  Returning to FIG. 6, description will be continued. In step 606, the flood simulation program 131 passes the inundation depth distribution to the geographic information management program 132. The geographic information management program 132 displays the inundation depth distribution in the window 200 or the window 400. Further, it is stored in the external storage device 120 as the inundation depth data file 123 as necessary. As described above, the inundation depth distribution shown in FIGS. 2 to 5 is generated by the series of processes shown in FIG.

  Although this embodiment has been described as an apparatus composed of one computer, it may be realized as an apparatus composed of a plurality of computers. FIG. 10 is a schematic block diagram showing the configuration of a computer system for realizing the present invention, which is composed of two computers. This is a configuration in which the geographic information management program 132 and the flood simulation program 131 are operated on different PCs (100, 1000). The processing and GUI performed by the geographic information management program 132 and the flood simulation program 131 alone are as described above. The order and contents of these programs communicating via the Internet 1050 will be described below. The geographic information management program 132 transmits a simulation start request to the flood simulation program 131. The flood simulation program 131 transmits a scenario data request and a terrain data request to the geographic information management program 132. When the inundation simulation is completed, the inundation simulation program 131 notifies the geographic information management program 132 of the end and transmits inundation depth data. The geographic information management program 132 displays the received inundation depth data in the window 200 or the window 400 and stores it in the external storage device 120 as the inundation depth file 123 as necessary. As described above, the geographic information management program 132 and the flood simulation program 131 can be operated on different computers. When the geographic information management program 132 and the flood simulation program 131 are executed on one PC, a processing delay may occur because the calculation load is too heavy. In the configuration shown in FIG. 10, this problem can be avoided.

  As described above, according to the present invention, it is possible to generate a detailed water depth distribution from a simulation result using a coarse lattice. This makes it possible to estimate the evacuation target area or flood damage in detail. Furthermore, according to the present invention, a natural water surface can be generated intuitively. Therefore, it is possible to generate realistic 3D CG such as a flooded cityscape from the simulation results.

1 is a schematic block diagram showing the configuration of a computer system for realizing the present invention in this embodiment. The figure which shows main GUI of the geographic information management program 132 when an interpolation function is invalid. The figure which shows main GUI of the geographic information management program 132 in case an interpolation function is effective. The figure which shows the water level cross section display window when an interpolation function is invalid. The figure which shows the water level cross section display window in case an interpolation function is effective. The PAD figure regarding the flood simulation process of the flood simulation program 131. The figure which shows the calculation grid and arrangement | positioning of a variable of a present Example. The figure for demonstrating the difference in the water surface shape in a normal flow and a jet stream. PAD diagram related to interpolation processing applying hydraulics performed in step 605. The schematic block diagram which shows the structure of the computer system for realizing this invention which consists of two computers.

Explanation of symbols

100 PC, 122 terrain data file, 131 flood simulation program, 132 geographic information management program, 201 mouse pointer, 210 map, 222 flooded area when interpolation function is disabled, 322 flooded area when interpolation function is enabled, 411 interpolation Water level profile when the function is disabled, 511 Water level profile when the interpolation function is enabled.

Claims (10)

An inundation simulation program for executing an inundation simulation in a computing device having at least a storage device for storing terrain data by a first grid and an arithmetic unit,
In the calculation unit,
A first step of performing hydraulic calculation using a second grid having a different arrangement from the first grid using topographic data read from the storage device, and outputting at least water depth data and water level data from the second grid When,
Using the water depth data or water level data by the second grid and the topographic data by the first grid, the water depth data or the water level by the first grid by spatially interpolating the water depth data or the water level data by the second grid. A flood simulation program characterized in that the second step of outputting as inundation data by data is executed. A flood simulation program according to claim 1,
The first step outputs whether the flow is a jet flow or a normal flow for each of the second grids in a hydraulic calculation,
In the second step, spatial interpolation by water depth data is performed in the second grid where the flow is a jet, and spatial interpolation is performed by water level data in the second grid where the flow is normal. Inundation simulation program. A flood simulation program according to claim 1,
The inundation simulation program characterized in that the first step includes a third step of resampling the topographic data by the first grid to the topographic data by the second grid. A flood simulation program according to claim 2,
In the second step, the ground level included in the terrain data by the first grid is obtained from the water level data by the first grid obtained by performing spatial interpolation using the water level data in the second grid in which the flow is normal. A flood simulation program characterized in that a value obtained by subtracting elevation data is output as water depth data by the first grid. A flood simulation program according to any one of claims 1 to 4,
An inundation simulation program, wherein the second lattice has a lower spatial density than the first lattice. A flood simulation method in a computing device having at least a storage device for storing terrain data by a first grid and an arithmetic unit,
The arithmetic unit performs hydraulic calculation using a second grid having a different arrangement from the first grid using the topographic data read from the storage device, and outputs at least water depth data and water level data by the second grid. A first step to:
Using the water depth data or water level data by the second grid and the topographic data by the first grid, the water depth data or the water level by the first grid by spatially interpolating the water depth data or the water level data by the second grid. And a second step of outputting as inundation data by data. A flood simulation method according to claim 6,
The first step outputs whether the flow is a jet flow or a normal flow for each of the second grids in a hydraulic calculation,
In the second step, spatial interpolation by water depth data is performed in the second grid where the flow is a jet, and spatial interpolation is performed by water level data in the second grid where the flow is normal. Inundation simulation method. A flood simulation method according to claim 6,
The flood simulation method according to claim 1, wherein the first step includes a third step of resampling the terrain data based on the first grid to the terrain data based on the second grid. A flood simulation method according to claim 7,
In the second step, the ground level included in the terrain data by the first grid is obtained from the water level data by the first grid obtained by performing spatial interpolation using the water level data in the second grid in which the flow is normal. A flood simulation method characterized by outputting a value obtained by subtracting altitude data as water depth data by the first grid. A flood simulation method according to any one of claims 6 to 9,
The flood simulation method, wherein the second lattice has a lower spatial density than the first lattice.