Flood monitoring device, flood monitoring system, and flood monitoring method

Abstract

To provide a flood monitoring device, a flood monitoring system and a flood monitoring method with which it is possible to calculate the water depth and stream speed of rivers with good accuracy, without using expensive sensors.SOLUTION: The present invention comprises: an acquisition unit that acquires a captured image having been captured by an imaging device that captures the image of a buoy on the water surface among buoy-type sensors having a buoy floating on a river and an unwinding mechanism that is connected to the buoy by a connecting line and capable of unwinding and pulling back the connecting line, and that is fixed to the bottom or near the bottom of the river; and a first calculation unit that derives, from the captured image, the horizontal displacement of the buoy from the water surface position in a direction perpendicular to the unwinding mechanism and the submerged state of the buoy, and calculates the water depth and stream speed of the river on the basis of the displacement, the submerged state, and a first relationship of balance of forces and tensions due to the gravity, buoyance and stream acting upon the buoy.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a flood monitoring device, a flood monitoring system, and a flood monitoring method.

Background Art

[0002] In recent years, along with natural disasters such as increasing heavy rain and earthquakes, there have been many flood damages caused by inundation of seawater or river water due to tsunamis or floods in areas near the sea or rivers.

[0003] As a technique for monitoring such floods, a method of measuring the river water level (water depth) by analyzing the difference from the normal monitoring image of the monitoring image of a river monitoring camera is disclosed (for example, Patent Document 1). Further, a method of distributing actual flood information that changes every moment due to the influence of water level, rainfall, etc. to promote evacuation is disclosed (for example, Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional technology, although the water depth (water level) is measured, the water flow velocity in the river cannot be measured, and there is a problem that the information for predicting the flood area is insufficient and the accuracy of the prediction is not high. Also, when a large number of expensive sensors for measuring the water level of a river are arranged in the river, there is a problem that the cost increases.

[0006] The present invention has been made in view of the above, and aims to provide a flood monitoring device, a flood monitoring system, and a flood monitoring method that can accurately calculate the water depth and water flow velocity of a river without using expensive sensors. [Means for solving the problem]

[0007] To solve the above-mentioned problems and achieve the objective, the present invention provides a buoy-type sensor comprising a buoy floating on a river and a deployment mechanism fixed to or near the riverbed of the river, connected to the buoy by a connecting wire and capable of deploying and retracting the connecting wire, characterized in that it comprises: an acquisition unit that acquires an image captured by an imaging device that images the buoy on the water surface; and a first calculation unit that derives from the image the horizontal displacement of the buoy from a position on the water surface perpendicular to the deployment mechanism, and the submersion state of the buoy, and calculates the water depth and water flow velocity of the river based on the displacement, the submersion state, and a first relationship of equilibrium between gravity, buoyancy, force and tension due to water flow acting on the buoy. [Effects of the Invention]

[0008] According to the present invention, the water depth and water flow velocity of a river can be calculated accurately without using expensive sensors. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a diagram illustrating the overall configuration of a flood monitoring system according to an embodiment. [Figure 2] Figure 2 illustrates the forces acting on the buoy. [Figure 3] Figure 3 shows an example of the hardware configuration of the predictive management server according to the embodiment. [Figure 4] Figure 4 shows an example of the hardware configuration of an information terminal according to the present invention. [Figure 5] Figure 5 shows an example of the configuration of the functional blocks of the predictive management server according to the embodiment. [Figure 6]Figure 6 is a flowchart showing an example of the calculation process flow for water depth and water flow velocity of the predictive management server according to the embodiment. [Figure 7] Figure 7 is a flowchart showing an example of the calculation process flow for another water depth and water flow velocity in the predictive management server according to the embodiment. [Figure 8] Figure 8 shows an example of a state in which evacuation routes are displayed on map information in an information terminal according to the embodiment. [Figure 9] Figure 9 shows an example of a state in which the predicted flood area and detour routes for evacuation are displayed on the map information of an information terminal according to the embodiment. [Figure 10] Figure 10 illustrates the forces and moments acting on the buoy. [Figure 11] Figure 11 is a flowchart showing an example of the calculation process flow for water depth and water flow velocity of the predictive management server according to Modification 1. [Figure 12] Figure 12 illustrates the forces and moments acting on an asymmetrical buoy. [Figure 13] Figure 13 is a flowchart showing an example of the water flow velocity calculation process of the predictive management server according to Modification 2. [Modes for carrying out the invention]

[0010] Embodiments of the flood monitoring device, flood monitoring system, and flood monitoring method according to the present invention will be described in detail below with reference to the drawings. Furthermore, the present invention is not limited by the following embodiments, and the components in the following embodiments include those that are easily conceivable by those skilled in the art, substantially identical, and so-called equivalents. Moreover, various omissions, substitutions, modifications, and combinations of components can be made without departing from the spirit of the following embodiments.

[0011] Note that computer software refers to programs related to the operation of a computer and other information used for computer processing that conforms to a program (hereinafter, computer software is referred to as software). Application software is a general term for software used to perform specific tasks among the classifications of software. On the other hand, an operating system (OS) is software that controls a computer and enables application software and the like to utilize computer resources. The operating system performs basic management and control of a computer, such as control of input / output, management of hardware such as memory and hard disks, and management of processes. Application software operates using the functions provided by the operating system. A program is a command for a computer, which is combined so that a single result can be obtained. Also, what conforms to a program refers to something that has a nature similar to a program in that it defines computer processing, although it is not a direct command for a computer and thus cannot be called a program. For example, a data structure (a logical structure of data represented by the mutual relationship between data elements) corresponds to something that conforms to a program.

[0012] (Overall Configuration of Flood Monitoring System) FIG. 1 is a diagram for explaining the overall configuration of a flood monitoring system according to an embodiment. While referring to FIG. 1, the overall configuration of the flood monitoring system 1 according to this embodiment will be described.

[0013] The flood monitoring system 1 shown in FIG. 1 is a system that calculates the water depth and water flow velocity of rivers and the like, and predicts the inundation area due to floods when floods occur due to inundation or the like. In this embodiment, the flood monitoring system 1 will be described with respect to the operation of calculating the water depth and water flow velocity in a river and predicting the inundation area when a flood occurs. As shown in FIG. 1, the flood monitoring system 1 includes a prediction management server 10 (flood monitoring device), a plurality of buoy-type sensors 20 installed in rivers and the like, and a monitoring camera 30.

[0014] The prediction management server 10 is a server device that calculates the water depth and water flow velocity of a river based on an imaging image of the buoy-type sensor 20 captured by the surveillance camera 30, and predicts the inundation area due to flooding when a flood occurs due to flooding or the like.

[0015] The buoy-type sensor 20 is a sensor mechanism that is installed in a plurality in a river and contributes to the calculation of the water depth and water flow velocity of the river by the prediction management server 10 by being imaged by the surveillance camera 30. As shown in FIG. 1, the buoy-type sensor 20 includes a buoy 21, a wire pay-out mechanism 22, and a wire 23 (connection line).

[0016] The buoy 21 is a buoy that is connected to a wire pay-out mechanism 22 installed on the river bottom or the like via a wire 23 and floats on the water surface of the river. As shown in FIG. 1, a mark 21a such as a character, a figure, or a symbol for deriving the inclination or the like of the buoy 21 is attached to the surface of the buoy 21.

[0017] The wire pay-out mechanism 22 includes a reel that houses a clock spring around which the wire 23 is wound, is connected to the buoy 21 via the wire 23 drawn from the reel, and according to the force received from the buoy 21 due to the movement of the buoy 21 on the water surface, the wire 23 is paid out from the reel, and as a result, a mechanism for generating tension in the wire 23 by utilizing the force for pulling back the wire 23 generated by the clock spring. The wire pay-out mechanism 22 is fixedly installed, for example, on the river bottom or a bridge close to the river bottom.

[0018] Wire 23 is a connecting wire that connects the buoy 21 and the wire feeding mechanism 22, and transmits the tension generated by the wire feeding mechanism 22 to the buoy 21. For example, an elastic body such as a coil spring is connected to one part of wire 23, and the elastic body stretches by a predetermined length according to the spring constant of the elastic body and the tension generated by the wire feeding mechanism 22. Therefore, the length of wire 23 and the tension generated in wire 23 (the combined force of the tension generated by the wire feeding mechanism 22 and the tension from the elastic body connected to one part of wire 23) are related by a predetermined relational equation, and if one is determined, the other can be derived. The relationship between the length of wire 23 and the tension generated in wire 23 may be obtained experimentally in advance. In principle, the longer the length of wire 23, the greater the tension. Note that wire 23 is not limited to metal, but may be made of resin, for example.

[0019] The surveillance camera 30 is an imaging device that captures images of multiple buoys 21 floating on the water surface. The surveillance camera 30 wirelessly transmits the captured images to the information terminal 40. Examples of wireless communication standards include 3G, LTE (Long Term Evolution), 4G, 5G, or Wi-Fi (registered trademark) (Wireless Fidelity).

[0020] The information terminal 40 is an information processing device such as a smartphone, tablet, or PC (Personal Computer) on which an application (hereinafter sometimes simply referred to as "the app") is installed that receives information such as predicted flood areas predicted by the prediction management server 10 and displays it on the map information. The app installed on the information terminal 40 may be either a native app or a web app.

[0021] (Regarding the forces acting on the buoy, etc.) Figure 2 illustrates the forces acting on the buoy. The forces acting on buoy 21 will be explained with reference to Figure 2.

[0022] First, let's explain the forces acting on buoy 21. Since buoy 21 has a known mass, we can consider that a downward gravitational force G acts on its center of gravity (the hatched "x" mark in Figure 2). As mentioned above, since the mass of buoy 21 is known, the value of the gravitational force G is also a known constant. The reason why the center of gravity of buoy 21 and the center (the filled "x" mark in Figure 2) are offset is that a weight 21b is built into the fulcrum 21c (connection point) where buoy 21 and wire 23 are connected, in order to suppress the swaying of buoy 21.

[0023] Furthermore, since buoy 21 is a floating buoy on the water surface, there is a portion of its volume that is submerged below the water surface (submerged volume), and a vertically upward buoyant force U acts on this submerged portion due to the water pressure difference. Specifically, the buoyant force U is calculated as the product of the submerged volume, the density of water, and the acceleration due to gravity. In Figure 1, this buoyant force U is illustrated as a force acting on the center of buoy 21. Here, the height from the water surface of the portion of buoy 21 that is visible above the water surface is defined as the apex height Δh (an example of a submerged state).

[0024] Furthermore, since buoy 21 is a floating buoy on the river, it is subjected to a force W due to the river's current, i.e., a force W due to the water flow. Also, as described above, since buoy 21 is connected to the wire payout mechanism 22 by a wire 23, it receives a tension T in the direction of the wire 23 at the fulcrum 21c, corresponding to the wire length L.

[0025] Furthermore, because the river has a current, the buoy 21 is subjected to a force W from the water flow, causing it to move horizontally by a displacement Δx from the vertical water surface position of the wire payout mechanism 22. As a result of the horizontal displacement Δx of the buoy 21, the direction of the wire 23 becomes inclined by an angle θ from the vertical, as shown in Figure 1.

[0026] The following explains the relationships between the variables and constants mentioned above. Here, the depth of the river to be calculated by the prediction management server 10 is denoted as water depth d, and the speed of the flow is denoted as water flow velocity v.

[0027] As shown in Figure 2, the relationship between wire length L, inclination angle θ, displacement Δx, and water depth d is Lcosθ=d and Lsinθ=Δx, so tanθ=Δx / d can be derived. In other words, since the inclination angle θ is a function of displacement Δx and water depth d, it shall be written as θ(d,Δx) when specifically indicated.

[0028] Furthermore, the vertex height Δh can be derived from the image captured by the surveillance camera 30. Alternatively, the position of the mark 21a on the surface of the buoy 21 may be used to derive the vertex height Δh from the image. For example, if the buoy 21 is spherical and its volume is known, the submerged volume of the buoy 21 can be calculated by deriving the vertex height Δh. Then, as described above, the buoyancy U can be calculated by the product of the submerged volume, the density of water, and the acceleration due to gravity. That is, since the buoyancy U is a function of the vertex height Δh, it should be denoted as U(Δh) when specifically indicated.

[0029] Furthermore, as described above, the wire length L of wire 23 and the tension generated in wire 23 are related by a predetermined relational equation, and if one is determined, the other can be derived. Therefore, the tension T is a function of the wire length L, and when this is specifically indicated, it will be written as T(L). In addition, due to the inclination angle θ of wire 23, the tension T can be decomposed into a horizontal component Tsinθ and a vertical component Tcosθ, as shown in Figure 2.

[0030] Furthermore, the force W acting on buoy 21 due to the water flow in the river is a function of the water flow velocity v, and when specifically indicated, it shall be denoted as W(v).

[0031] Furthermore, the vertical force acting on buoy 21 as described above is related by the equilibrium equation shown in equation (1) below.

[0032] U(Δh)=G+T(L)·cosθ(d,Δx) ···(1)

[0033] In other words, the buoyant force U is equal to the resultant force of gravity G and the vertical component Tcosθ of tension T.

[0034] Furthermore, the horizontal forces acting on buoy 21 are related by the equilibrium equation shown in equation (2) below.

[0035] W(v)=T(L)·sinθ(d,Δx)···(2)

[0036] In other words, the force W due to the water flow is equal to the horizontal component Tsinθ of the tension T.

[0037] From the above, the prediction management server 10 can calculate the water depth d and water flow velocity v by numerical calculation using the functional relationship between the variables and the above equations (1) and (2). Note that the above equations (1) and (2) correspond to the first relationship.

[0038] (Hardware configuration of the predictive management server) Figure 3 shows an example of the hardware configuration of the predictive management server according to this embodiment. The hardware configuration of the predictive management server 10 according to this embodiment will be described with reference to Figure 3.

[0039] As shown in Figure 3, the predictive management server 10 includes a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, an auxiliary storage device 505, a network interface 508, a display 509, a keyboard 511, and a mouse 512.

[0040] The CPU 501 is a processing unit that controls the overall operation of the predictive management server 10. The ROM 502 is a non-volatile memory device that stores programs for the predictive management server 10. The RAM 503 is a volatile memory device used as the work area for the CPU 501.

[0041] The auxiliary storage device 505 is a storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) that stores various data and programs.

[0042] Network I / F 508 is an interface for wirelessly transmitting data between the surveillance camera 30 and the information terminal 40. Standards for wireless communication include 3G, LTE, 4G, 5G, or Wi-Fi (registered trademark).

[0043] The display 509 is a display device composed of liquid crystal or organic EL, etc., which displays various information such as cursors, menus, windows, characters, or images.

[0044] The keyboard 511 is an input device for selecting characters, numbers, various instructions, and moving the cursor. The mouse 512 is an input device for selecting and executing various instructions, selecting the object to be processed, and moving the cursor.

[0045] The CPU 501, ROM 502, RAM 503, auxiliary storage device 505, network interface 508, display 509, keyboard 511, and mouse 512 described above are connected to each other via bus lines 510, such as an address bus and a data bus, enabling communication between them.

[0046] Note that the hardware configuration of the predictive management server 10 shown in Figure 3 is just one example, and it is not necessary to include all of the components shown in Figure 3, or other components may be included.

[0047] (Hardware configuration of information terminals) Figure 4 shows an example of the hardware configuration of an information terminal according to this embodiment. The hardware configuration of the information terminal 40 according to this embodiment will be described with reference to Figure 4.

[0048] As shown in Figure 4, the information terminal 40 includes a CPU 401, a ROM 402, a RAM 403, an EEPROM (Electrically Erasable Programmable Read Only Memory) 404, an imaging unit 405, an imaging interface 406, an acceleration / direction sensor 407, and a GPS (Global Positioning System) receiver 408.

[0049] The CPU 401 is a processing unit that controls the operation of the entire information terminal 40. The ROM 402 is a non-volatile memory device that stores programs used to drive the CPU 401, such as the IPL (Initial Program Loader). The RAM 403 is a volatile memory device used as the work area of ​​the CPU 401. The EEPROM 404 is a non-volatile memory device that stores programs and various other data.

[0050] The imaging unit 405 is a built-in imaging device that, under the control of the CPU 401, captures images of a subject using an image sensor such as a CCD (Charge-Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) to obtain image data. The imaging I / F 406 is an interface for controlling the operation of the imaging unit 405.

[0051] The accelerometer / directional sensor 407 is a combination of various sensors, including an electronic magnetic compass for detecting the Earth's magnetic field, a gyrocompass, and an accelerometer.

[0052] The GPS receiver 408 is a receiving device that receives GPS signals from GPS satellites. It is not limited to GPS; other GNSS (Global Navigation Satellite System) systems may also be used.

[0053] Furthermore, as shown in Figure 4, the information terminal 40 also includes a long-range communication circuit 410, an antenna 410a, a short-range communication circuit 411, an antenna 411a, a microphone 412, a speaker 413, an audio input / output interface 414, a display 415, an external device connection interface 416, a vibrator 417, and a touch panel 418.

[0054] The long-distance communication circuit 410 is a communication circuit that wirelessly communicates with other devices via antenna 410a using standards such as Wi-Fi (registered trademark).

[0055] The short-range communication circuit 411 is a communication circuit that performs short-range wireless communication with other devices via antenna 411a using standards such as NFC (Near Field Communication) or Bluetooth (registered trademark).

[0056] Microphone 412 is a built-in sound collection device that converts sound into electrical signals. Speaker 413 is a built-in acoustic device that converts electrical signals into physical vibrations to output sound such as music or speech. Sound input / output interface 414 is an interface that processes the input and output of sound signals between microphone 412 and speaker 413 according to the control of CPU 401.

[0057] Display 415 is a display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display that displays images of the subject, various icons, etc. External device connection I / F 416 is an interface conforming to standards such as USB (Universal Serial Bus) for connecting various external devices.

[0058] The vibrator 417 is a device that generates physical vibrations according to the control of the CPU 401.

[0059] The touch panel 418 is an input device that allows users to activate various functions of the information terminal 40 by touching the display 415.

[0060] The CPU 401, ROM 402, RAM 403, EEPROM 404, imaging interface 406, acceleration / direction sensor 407, GPS receiver 408, long-range communication circuit 410, short-range communication circuit 411, sound input / output interface 414, display 415, external device connection interface 416, vibrator 417, and touch panel 418 are all connected to each other via bus lines 409, such as an address bus and a data bus, enabling communication between them.

[0061] Note that the hardware configuration of the information terminal 40 shown in Figure 4 is just one example, and it is not necessary to have all of the components, nor is it necessary to have other components.

[0062] (Configuration and operation of the functional blocks of the predictive management server) Figure 5 shows an example of the configuration of the functional blocks of the predictive management server according to this embodiment. The configuration and operation of the functional blocks of the predictive management server 10 according to this embodiment will be described with reference to Figure 5.

[0063] As shown in Figure 5, the prediction management server 10 includes an acquisition unit 101, a first calculation unit 102, a prediction unit 103, a second calculation unit 104, and a display control unit 105.

[0064] The acquisition unit 101 is a functional unit that acquires images of the buoy 21 captured by multiple buoy-type sensors 20 via the network I / F 508.

[0065] The first calculation unit 102 is a functional unit that calculates the river's water depth d and water flow velocity v based on the image captured by the acquisition unit 101. Details of the calculation method for water depth d and water flow velocity v by the first calculation unit 102 will be described later in Figures 6 and 7.

[0066] The prediction unit 103 is a functional unit that, in the event of a river flood, predicts the area of ​​inundation that will spread from the point of flooding, etc., in a time series based on pre-prepared map information and the water depth d and water flow velocity v calculated by the first calculation unit 102. In this case, the map information includes, for example, topographic information such as land elevation, road information, and information on the size and location of buildings.

[0067] The second calculation unit 104 is a functional unit that calculates an evacuation route that bypasses the flooded area (predicted flooded area) predicted by the prediction unit 103, and the evacuation time when using that evacuation route. For example, the second calculation unit 104 calculates the shortest route that bypasses the predicted flooded area as an evacuation route from the user's home to a designated evacuation shelter on the information terminal 40.

[0068] The display control unit 105 is a functional unit that controls the display operation of the information terminal 40, for example, on which a web application is running, via the network interface 508. The display control unit 105, for example, overlays the predicted flood area predicted by the prediction unit 103 onto the map information displayed on the display 415 of the information terminal 40, and also overlays the evacuation route and evacuation time calculated by the second calculation unit 104 onto the map information.

[0069] The acquisition unit 101, the first calculation unit 102, the prediction unit 103, the second calculation unit 104, and the display control unit 105 described above are implemented by the execution of a program by the CPU 501 shown in Figure 3. At least a portion of these functional units may be implemented by hardware circuits such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application Specific Integrated Circuits).

[0070] Note that the functional units of the predictive management server 10 shown in Figure 5 are conceptual representations of their functions and are not limited to this configuration. For example, multiple functional units shown as independent functional units in the predictive management server 10 in Figure 5 may be configured as a single functional unit. Alternatively, the functions of a single functional unit in the predictive management server 10 shown in Figure 5 may be divided into multiple functions and configured as multiple functional units.

[0071] (Process flow for calculating water depth and water flow velocity on the prediction management server) Figure 6 is a flowchart showing an example of the calculation process flow for water depth and water flow velocity by the predictive management server according to this embodiment. The calculation process flow for water depth and water flow velocity by the predictive management server 10 according to this embodiment will be explained with reference to Figure 6.

[0072] <Step S11> The acquisition unit 101 of the predictive management server 10 acquires images of the buoy 21 from multiple buoy-type sensors 20 captured by the surveillance camera 30 via the network interface 508. The first calculation unit 102 of the predictive management server 10 derives the vertex height Δh of the buoy 21 of the buoy-type sensor 20 from the images acquired by the acquisition unit 101. The first calculation unit 102 may use the position of the mark 21a on the surface of the buoy 21 to derive the vertex height Δh from the images. Then, the process proceeds to step S12.

[0073] <Step S12> The first calculation unit 102 derives the horizontal displacement Δx of the buoy 21 floating on the river surface from the image captured by the acquisition unit 101. Then, it proceeds to step S13.

[0074] <Step S13> The first calculation unit 102 then calculates the water depth d and water flow velocity v based on the buoyancy U determined from gravity G and the apex height Δh, as well as the above-mentioned equations (1) and (2). For example, the inclination angle θ, tension T, wire length L, and force W due to the water flow can be said to be dependent values ​​of the water depth d and water flow velocity v, so the water depth d and water flow velocity v can be calculated by numerical calculation.

[0075] Following the steps S11 to S13 described above, the prediction management server 10 performs the calculation process for water depth and water flow velocity.

[0076] Here, an example of a specific method for calculating the water depth d and water flow velocity v in step S13 is described below.

[0077] The first calculation unit 102 calculates the submerged volume of the buoy 21 from the derived vertex height Δh. Then, the first calculation unit 102 calculates the buoyancy U by multiplying the submerged volume, the density of water, and the acceleration due to gravity.

[0078] Next, the first calculation unit 102 calculates the vertical component Tcosθ of the tension T from the known gravity G, the calculated buoyancy U, and the above-mentioned equation (1). Furthermore, the displacement Δx calculated in step S12 above is expressed as Δx = Lsinθ using the wire length L and the inclination angle θ.

[0079] Next, the first calculation unit 102 calculates the wire length L and the inclination angle θ from the vertical component Tcosθ of the calculated tension T and the derived displacement Δx (=Lsinθ). As mentioned above, the tension T is a function of the wire length L and can be expressed using the wire length L, so it can be solved as a system of equations between the wire length L and the inclination angle θ.

[0080] Next, the first calculation unit 102 calculates the water depth d (=Lcosθ) from the wire length L and the inclination angle θ.

[0081] Next, the first calculation unit 102 calculates the tension T from the calculated wire length L. Then, the first calculation unit 102 calculates the force W due to the water flow from the calculated tension T and inclination angle θ using equation (2) described above. Then, the first calculation unit 102 calculates the water flow velocity v, which is the inverse function of the force W due to the water flow.

[0082] As described above, the first calculation unit 102 calculates the water depth d and the water flow velocity v.

[0083] As shown in Figure 2 above, in cases such as when the water flow velocity v is above a predetermined value, the inclination of the buoy 21 with respect to the vertical (an example of a submerged state) can be considered as the inclination angle θ in the direction of the wire 23. That is, in this case, the apex of the buoy 21 (the position where mark 21a is located) lies on the extension of the wire 23. The calculation process for the water depth d and water flow velocity v in this case will be explained below with reference to Figure 7.

[0084] Figure 7 is a flowchart showing another example of the calculation process flow for water depth and water flow velocity in the predictive management server according to the embodiment. Referring to Figure 7, the calculation process flow for water depth and water flow velocity when the apex of buoy 21 (the position where mark 21a is located) is located on the extension of wire 23 will be explained.

[0085] <Step S21> The acquisition unit 101 of the predictive management server 10 acquires images of the buoy 21 from multiple buoy-type sensors 20 captured by the surveillance camera 30 via the network interface 508. The first calculation unit 102 of the predictive management server 10 derives the tilt angle θ of the buoy 21 from the images acquired by the acquisition unit 101, based on the position of the mark 21a on the buoy 21 of the buoy-type sensor 20. Then, the process proceeds to step S22.

[0086] <Step S22> The first calculation unit 102 derives the horizontal displacement Δx of the buoy 21 floating on the river surface from the image captured by the acquisition unit 101. Then, the process proceeds to step S23.

[0087] <Step S23> The first calculation unit 102 calculates the wire length L from the displacement Δx and the inclination angle θ, since the displacement Δx is expressed as Δx = Lsinθ using the wire length L and the inclination angle θ. Next, the first calculation unit 102 calculates the water depth d (= Lcosθ) from the wire length L and the inclination angle θ. Then, it proceeds to step S24.

[0088] <Step S24> The first calculation unit 102 calculates the tension T from the calculated wire length L. Next, the first calculation unit 102 calculates the force W due to the water flow from the calculated tension T and inclination angle θ using the above-mentioned equation (2). Then, it proceeds to step S25.

[0089] <Step S25> The first calculation unit 102 then calculates the water flow velocity v, which is the inverse function of the force W due to the water flow.

[0090] Based on the above, when the apex of buoy 21 (the position where mark 21a is located) is on the extension of wire 23, the first calculation unit 102 calculates the water depth d and the water flow velocity v.

[0091] (Display operation of predicted flood area, evacuation routes, and evacuation times on information terminals) Figure 8 shows an example of a state in which evacuation routes are displayed on the map information in an information terminal according to the embodiment. Figure 9 shows an example of a state in which the predicted flood area and detour routes for evacuation are displayed on the map information in an information terminal according to the embodiment. Referring to Figures 8 and 9, the display operation of the predicted flood area, evacuation routes, and evacuation time on the map information of the information terminal 40 will be explained.

[0092] In the example shown in Figure 8, when the river is not flooded, the display control unit 105 displays the evacuation route and evacuation time calculated by the second calculation unit 104 superimposed on the map information on the display 415 of the information terminal 40. Specifically, in Figure 8, the evacuation route LT1 from the user's home to the evacuation shelter and the evacuation time are displayed superimposed on the map information on the display 415 of the information terminal 40.

[0093] Next, in the example shown in Figure 9, when a river overflows, the display control unit 105 displays on the display 415 of the information terminal 40, superimposed on the map information, the predicted flood area FA at a specific time predicted by the prediction unit 103, and the evacuation route LT2 and evacuation time that bypass the predicted flood area FA calculated by the second calculation unit 104.

[0094] Furthermore, the information terminal 40 may allow the user to select how many minutes from the current time the predicted flooded area FA is. In this case, the predicted flooded area after the selected time has elapsed is predicted again by the prediction unit 103, and the second calculation unit 104 calculates an evacuation route and evacuation time that bypasses the predicted flooded area.

[0095] As described above, in the predictive management server 10 according to this embodiment, the acquisition unit 101 acquires images captured by a surveillance camera 30 that images the buoy 21 on the water surface, which is part of a buoy-type sensor 20 having a buoy 21 floating on the river and a wire feed mechanism 22 fixed to or near the riverbed of the river and connected to the buoy 21 by a wire 23, allowing the wire 23 to be fed out and retracted. The first calculation unit 102 derives from the captured images the horizontal displacement Δx of the buoy 21 from a position on the water surface perpendicular to the wire feed mechanism 22, and the submersion state of the buoy 21 (vertex height Δh, inclination of the buoy 21). Based on the displacement Δx, the submersion state, and the equilibrium equations (1) and (2) of gravity G, buoyancy U, and force W due to water flow acting on the buoy 21, the water depth d and water flow velocity v of the river are calculated. This eliminates the need for power to send or receive signals or information from buoy 21, allowing for accurate calculation of river water depth d and water flow velocity v without the use of expensive sensors.

[0096] Furthermore, in the prediction management server 10 according to this embodiment, the prediction unit 103 predicts the flooded area from the river in a time series based on predetermined map information and the water depth d and water flow velocity v calculated by the first calculation unit 102, the second calculation unit 104 calculates evacuation routes and evacuation times that bypass the flooded area predicted by the prediction unit 103, and the display control unit 105 displays the flooded area predicted by the prediction unit 103, as well as the evacuation routes and evacuation times calculated by the second calculation unit 104, superimposed on the map information on the information terminal 40. As a result, the user of the information terminal 40 can confirm the flooded area with high prediction accuracy, and can also confirm evacuation routes and evacuation times that bypass the flooded area, so that even if flooding occurs, they can safely evacuate to an evacuation center.

[0097] (Variation 1) Next, we will explain the differences between the prediction management server 10 according to Modification 1 and the prediction management server 10 according to the above embodiment. In this modification, we will explain the calculation process for water depth d and water flow velocity v, taking into account the deviation in the tilt of the buoy 21 caused by the force moment around the support point 21c of the buoy 21 in the vertical plane.

[0098] Figure 10 illustrates the forces and moments acting on the buoy. Referring to Figure 10, the forces and moments acting on buoy 21 will be explained.

[0099] As shown in Figure 10, the forces acting on buoy 21 are the same as those described in Figure 2 above. However, with respect to the moment of force around the support point 21c in the vertical plane, which will be explained below, the tension T where the support point 21c lies on the line of the force vector does not contribute to the moment of force around the support point 21c and is therefore not shown in Figure 10.

[0100] As shown in Figure 10, the moment of force around the fulcrum 21c in the vertical plane includes the moment of buoyancy U, the moment of gravity G, and the moment of force W due to the water flow. When these moment of force are balanced, the rotational motion of the buoy 21 around the fulcrum 21c ceases.

[0101] The moment of buoyancy U is expressed as the product of the component of the buoyancy U vector perpendicular to the line connecting the starting point (the center of buoy 21 in the example of Figure 10) and the pivot point 21c, and the distance between the starting point and the pivot point 21c (hereinafter referred to as distance r1), as shown in Figure 10. More precisely, the moment of buoyancy U is obtained by integrating the product of the component of the buoyancy force vector acting on each point of the submerged volume of buoy 21 perpendicular to the line connecting the starting point and the pivot point 21c, and the distance between the starting point and the pivot point 21c, over the entire submerged volume. In the example shown in Figure 10, the moment of buoyancy U contributes to a clockwise rotation around the pivot point 21c.

[0102] The moment of gravity G is expressed as the product of the component of the gravity G vector perpendicular to the line connecting the starting point (the center of gravity of buoy 21 in the example of Figure 10) and the pivot point 21c, and the distance between the starting point and the pivot point 21c (hereinafter referred to as distance r²), as shown in Figure 10. More precisely, the moment of gravity G is obtained by integrating the product of the component of the gravity vector acting on each point mass in buoy 21 perpendicular to the line connecting the starting point and the pivot point 21c, and the distance between the starting point and the pivot point 21c, over the entire volume of buoy 21. In the example shown in Figure 10, the moment of gravity G contributes to a counterclockwise rotation around the pivot point 21c.

[0103] The moment of the force W due to the water flow is obtained by integrating the product of the force vector (directed to the left) due to the water flow acting on each point on the surface of the submerged portion of the buoy 21, which is perpendicular to the line connecting the starting point and the fulcrum 21c, and the distance between the starting point and the fulcrum 21c, over the entire surface of the submerged portion. However, of the moment of the force W due to the water flow, the moment contributing to counterclockwise rotation around the fulcrum 21c is denoted as W1, and the moment contributing to clockwise rotation is denoted as W2.

[0104] Assuming that the moment of buoyancy U, the moment of gravity G, and the moment of force W due to the water flow are in equilibrium, they can be related by the equilibrium equation shown in equation (3) below.

[0105] r1·U(Δh)·sin(θ-φ)+W2=r2·G·sin(θ-φ)+W1 ...(3)

[0106] The displacement angle φ shown in equation (3) is the displacement angle of the line connecting the vertex of the buoy 21 (the point where the line connecting the fulcrum 21c and the center of gravity intersects the surface) with respect to the direction of the wire 23, as shown in Figure 10, resulting from the moment of each force acting on the buoy 21 around the fulcrum 21c. Therefore, the inclination of the buoy 21 (an example of a submerged state) is expressed as θ-φ. Note that equation (3) above corresponds to the second relationship.

[0107] Figure 11 is a flowchart showing an example of the calculation process flow for water depth and water flow velocity of the predictive management server according to Modification 1. The calculation process flow for water depth and water flow velocity by the predictive management server 10 according to this modification will be explained with reference to Figure 11.

[0108] <Step S31> The acquisition unit 101 of the predictive management server 10 acquires images of the buoy 21 from multiple buoy-type sensors 20 captured by the surveillance camera 30 via the network interface 508. The first calculation unit 102 of the predictive management server 10 derives the vertex height Δh of the buoy 21 of the buoy-type sensor 20 from the images acquired by the acquisition unit 101. The first calculation unit 102 may use the position of the mark 21a on the surface of the buoy 21 to derive the vertex height Δh from the images. The first calculation unit 102 also derives the inclination of the buoy 21, θ-φ, from the position of the mark 21a on the buoy 21 in the images. Then, the process proceeds to step S32.

[0109] <Step S32> The first calculation unit 102 derives the horizontal displacement Δx of the buoy 21 floating on the river surface from the image captured by the acquisition unit 101. Then, the process proceeds to step S33.

[0110] <Step S33> The first calculation unit 102 then calculates the water depth d, water flow velocity v, and slip angle φ based on the buoyancy U determined from gravity G and vertex height Δh, as well as the above-mentioned equations (1) to (3). For example, since the other values ​​can be said to be dependent on the water depth d, water flow velocity v, and slip angle φ, the water depth d, water flow velocity v, and slip angle φ can be calculated by numerical calculation.

[0111] Following the steps S31 to S33 described above, the prediction management server 10 performs the calculation process for water depth and water flow velocity.

[0112] As described above, in the prediction management server 10 according to this modified example, the first calculation unit 102 derives the height Δh of the vertex of the portion of the buoy 21 that is visible above the water surface from the captured image as the submerged state, and derives the inclination of the buoy having a slip angle φ with respect to the direction of the wire 23 from the captured image as the submerged state, and calculates the water depth d and water flow velocity v based on the displacement Δx, the submerged state, equations (1) and (2), and equation (3) for the equilibrium of the moments of gravity G, buoyancy U, and force W due to the water flow around the support point 21c, which is the connection point between the buoy 21 and the wire 23 in the vertical plane. As a result, since no power is required to send or receive any signals or information about the buoy 21, the water depth d and water flow velocity v of the river can be calculated accurately without using expensive sensors, and the water depth d and water flow velocity v can also be calculated accurately even when there is a slip angle φ in the inclination of the buoy 21.

[0113] (Modification 2) Next, we will explain the differences between the predictive management server 10 according to the modified example 2 and the predictive management server 10 according to the embodiment described above. In this modified example, we will explain the process for calculating the water flow velocity v, taking into account the displacement angle of the buoy 21 with respect to the water flow direction, which is caused by the moment of force W due to the water flow around the pivot point 21c of the asymmetrical buoy 21 in the horizontal plane.

[0114] Figure 12 illustrates the forces and moments acting on an asymmetrical buoy. Referring to Figure 12, the moment of the force W due to the water flow acting on buoy 21 in the horizontal plane will be explained.

[0115] Figure 12 shows the state of buoy 21 as seen from above, and it is assumed that buoy 21 is asymmetrical. The part exposed above the water surface 21d is the volume of buoy 21 that is exposed above the water surface. As shown in Figure 12, the moment of force around the fulcrum 21c in the horizontal plane is the moment of force W due to the water flow. Buoyancy U and gravity G are forces that act perpendicular to the horizontal plane, and therefore do not contribute to the moment of force around the fulcrum 21c in the horizontal plane.

[0116] The moment of the force W due to the water flow is obtained by integrating the product of the force vector (directed to the left) acting on each point on the surface of the submerged portion of the buoy 21, which is perpendicular to the line connecting the starting point and the fulcrum 21c, and the distance between the starting point and the fulcrum 21c (hereinafter referred to as distance r), over the entire surface of the submerged portion, as shown in Figure 12. Here, with respect to the moment of the moment of the force W due to the water flow that contributes to counterclockwise rotation around the fulcrum 21c, the component of the force vector acting on each point on the surface of the submerged portion of the buoy 21 that is perpendicular to the line connecting the starting point and the fulcrum 21c is denoted as W3. On the other hand, with respect to the moment of the moment of the moment of the force W due to the water flow that contributes to clockwise rotation around the fulcrum 21c, the component of the force vector acting on each point on the surface of the submerged portion of the buoy 21 that is perpendicular to the line connecting the starting point and the fulcrum 21c is denoted as W4.

[0117] Assuming that the moment forces due to the water flow acting on each point on the surface of the submerged portion of buoy 21 are in equilibrium, they can be related by the equilibrium equation shown in equation (4) below.

[0118] ∫r×W3(v,λ,r)dr=∫r×W4(v,λ,r)dr ···(4)

[0119] The horizontal displacement angle λ shown in equation (4) is the horizontal displacement angle of the line connecting the vertex of the buoy 21 (the point where the line connecting the fulcrum 21c and the center of gravity intersects the surface) to the fulcrum 21c, with respect to the direction of the wire 23, as shown in Figure 12, resulting from the force moment acting on the buoy 21 due to the water flow centered at the fulcrum 21c. In this case, W3 and W4 are functions of the water flow velocity v, the horizontal displacement angle λ, and the distance r. Note that equation (4) above corresponds to the third relationship.

[0120] In order for the buoy 21 to maintain asymmetry without tipping over when the force moment due to the water flow is in equilibrium, more than half of the asymmetrical volume must be submerged in water. By positioning the weight 21b in the submerged portion of the buoy 21, tipping can be suppressed.

[0121] Figure 13 is a flowchart showing an example of the water flow velocity calculation process of the predictive management server according to Modification 2. The water flow velocity calculation process by the predictive management server 10 according to this modification will be explained with reference to Figure 13.

[0122] <Step S41> The acquisition unit 101 of the predictive management server 10 acquires images of the buoy 21 captured by the surveillance camera 30 from multiple buoy-type sensors 20 via the network interface 508. The first calculation unit 102 derives the horizontal displacement angle λ of the buoy 21 in the horizontal plane from the position of the mark 21a on the buoy 21 in the captured image. Then, the process proceeds to step S42.

[0123] <Step S42> The first calculation unit 102 numerically calculates the water flow velocity v from the horizontal displacement angle λ and the equation (4) for the equilibrium of force moments due to the water flow acting on each point on the surface of the submerged portion of the buoy 21.

[0124] The water flow velocity calculation process is performed by the predictive management server 10 following the steps S41 to S42 described above.

[0125] As described above, in the prediction management server 10 according to this modified example, the first calculation unit 102 derives the horizontal displacement angle λ of the buoy 21 in the horizontal plane from the captured image, and calculates the water flow velocity v based on the horizontal displacement angle λ and equation (4) for the equilibrium of each moment of force due to the water flow around the fulcrum 21c, which is the connection point between the buoy 21 and the wire 23 in the horizontal plane. As a result, since no power is required to send or receive any signals or information about the buoy 21, the water flow velocity v of the river can be calculated accurately without using expensive sensors.

[0126] Furthermore, each function of the embodiments and variations described above can be realized by one or more processing circuits. Here, "processing circuit" includes processors programmed to execute each function by software, such as processors implemented by electronic circuits, as well as devices such as ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), FPGAs (Field Programmable Gate Arrays), and conventional circuit modules designed to execute each function described above.

[0127] Furthermore, the programs executed by the predictive management server 10 in the above-described embodiments and each modified example may be configured to be pre-installed and provided in ROM or the like.

[0128] Furthermore, the programs executed by the predictive management server 10 in the above-described embodiments and each of its variations may be configured to be recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD), a CD-R (Compact Disc-Recordable), or a DVD (Digital Versatile Disc) and provided as a computer program product.

[0129] Furthermore, the programs executed by the predictive management server 10 in the above-described embodiments and their respective modifications may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Alternatively, the programs executed by the predictive management server 10 in the above-described embodiments and their respective modifications may be provided or distributed via a network such as the Internet.

[0130] Furthermore, the programs executed by the predictive management server 10 in the above-described embodiments and each modified example are configured as modules including the above-described functional units. In actual hardware, the CPU 501 (processor) reads the program from the ROM 502 or auxiliary storage device 505 and executes it, thereby loading the above-described functional units onto the RAM 503 (main memory), and creating each functional unit on the RAM 503. [Explanation of Symbols]

[0131] 1. Flood monitoring system 10 Predictive Management Server 20 Buoy-type sensors 21 V 21a Mark 21b Weight 21c fulcrum 21d Above water surface 22 Wire feeding mechanism 23 wires 30 surveillance cameras 40 Information terminals 101 Acquisition Department 102 First Calculation Unit 103 Prediction Section 104 Second Calculation Unit 105 Display Control Unit 401 CPU 402 ROM 403 RAM 404 EEPROM 405 Imaging Unit 406 IMAGING I / F 407 Acceleration and compass sensor 408 GPS receiver 409 Bus Line 410 Telecommunications circuit 410a antenna 411 Near field communication circuit 411a antenna 412 Mike 413 Speakers 414 Audio Input / Output Interface 415 displays 416 External device connection interface 417 Vibrator 418 Touch Panel 501 CPU 502 ROM 503 RAM 505 Auxiliary storage 508 Network Interface 509 Display 510 Bus Line 511 keyboard 512 mice d water depth FA predicted flood area G gravity L Wire Length LT1, LT2 Evacuation Routes T tension U buoyancy v Water velocity W: Force due to water flow θ Tilt angle λ Horizontal displacement angle φ offset angle Δh vertex height Δx displacement

Claims

1. A buoy-type sensor having a buoy floating on a river and a deployment mechanism fixed to the riverbed or near the riverbed, which is connected to the buoy by a connecting wire and is capable of deploying and retracting the connecting wire, wherein the sensor includes an acquisition unit that acquires an image captured by an imaging device that images the buoy on the water surface, A first calculation unit derives from the captured image the horizontal displacement of the buoy from the water surface position vertical to the deployment mechanism, and the submersion state of the buoy, and calculates the water depth and water flow velocity of the river based on the displacement, the submersion state, and a first relationship of equilibrium between gravity, buoyancy, force and tension due to water flow acting on the buoy. A flood monitoring device equipped with a flood monitoring system.

2. The first calculation unit is, From the aforementioned captured image, the height of the portion of the buoy that is visible above the water surface is derived as the submerged state. A flood monitoring device according to claim 1, which calculates the submerged volume of the buoy from the height, calculates the buoyancy of the buoy based on the submerged volume, and calculates the water depth and the water flow velocity based on the displacement, the buoyancy, and the first relationship.

3. The first calculation unit derives the inclination of the buoy with respect to the vertical direction as the submerged state from the captured image, as the angle of inclination of the connecting line with respect to the vertical direction. From the displacement and the angle of inclination, the length of the connecting wire is calculated, and from the length and the angle of inclination, the water depth is calculated. The flood monitoring device according to claim 1, which calculates the tension acting on the buoy at the connection point between the buoy and the connecting line from the aforementioned length, calculates the force due to the water flow acting on the buoy based on the aforementioned tension and the aforementioned inclination angle, and calculates the water flow velocity from the force due to the water flow.

4. The buoy has a mark on its surface, The flood monitoring device according to claim 3, wherein the first calculation unit derives the inclination from the captured image based on the position of the mark on the buoy.

5. The first calculation unit is, From the aforementioned captured image, the height of the portion of the buoy that is visible above the water surface is derived as the submerged state. From the captured image, the tilt of the buoy having a deviation angle with respect to the direction of the connecting line is derived as the submerged state. A flood monitoring device according to claim 1, which calculates the water depth and the water flow velocity based on the displacement, the submersion state, the first relationship, and the second relationship of the equilibrium of the moments of gravity, buoyancy, and force due to the water flow around the connection point between the buoy and the connecting line in a vertical plane.

6. The first calculation unit is, From the aforementioned captured image, the horizontal displacement angle of the buoy in the horizontal plane is derived. The flood monitoring device according to claim 1, which calculates the water flow velocity based on the horizontal displacement angle and a third relationship of equilibrium of each moment of force due to the water flow around the connection point between the buoy and the connecting line in the horizontal plane.

7. A flood monitoring device according to any one of claims 1 to 6, further comprising a prediction unit that predicts the area of ​​inundation from the river based on predetermined map information and the water depth and water flow velocity calculated by the first calculation unit.

8. The flood monitoring device according to claim 7, further comprising a second calculation unit for calculating an evacuation route and evacuation time that bypasses the flooded area predicted by the prediction unit.

9. The flood monitoring device according to claim 8, further comprising a display control unit that superimposes the flooded area predicted by the prediction unit, and the evacuation route and evacuation time calculated by the second calculation unit onto the map information and displays them on an information terminal.

10. A buoy-type sensor having a buoy floating in a river, and a deployment mechanism fixed to the riverbed or near the riverbed, which is connected to the buoy by a connecting wire and allows the connecting wire to be extended and retracted. An imaging device for imaging the buoy on the water surface, A flood monitoring device that calculates the water depth and water flow velocity of the river based on the images captured by the aforementioned imaging device, Includes, The aforementioned flood monitoring device, An acquisition unit that acquires the captured image from the imaging device, A first calculation unit derives from the captured image the horizontal displacement of the buoy from the water surface position vertical to the deployment mechanism, and the submersion state of the buoy, and calculates the water depth and water flow velocity based on the displacement, the submersion state, and a first relationship of equilibrium between gravity, buoyancy, force and tension due to water flow acting on the buoy, A flood monitoring system equipped with a flood monitoring system.

11. A flood monitoring method performed by a flood monitoring device, A buoy-type sensor having a buoy floating on a river and a deployment mechanism fixed to the riverbed or near the riverbed, which is connected to the buoy by a connecting wire and is capable of deploying and retracting the connecting wire, wherein the sensor acquires an image captured by an imaging device that images the buoy on the water surface. From the captured image, the horizontal displacement of the buoy from the water surface position perpendicular to the deployment mechanism, and the submersion state of the buoy are derived, and based on the displacement, the submersion state, and a first relationship of equilibrium between gravity, buoyancy, force due to water flow, and tension acting on the buoy, the water depth and water flow velocity of the river are calculated. A flood monitoring method characterized by including the following:

Images