Flow rate estimation system

Abstract

To solve a conventional problem, that is, to provide a flow rate estimation system capable of estimating a flow rate at any location in a water area.SOLUTION: A flow rate estimation system, which is a system for estimating a flow rate at any location in a water area set to an object range, includes water part area setting means, maximum width length extraction means, area setting means, water part proportion calculation means, and relation formula setting means. The relation formula setting means among them is means for setting a "flow rate relation formula" indicating a relationship between a water part proportion of a divided region relating to an observation point where an observed flow rate is obtained in the water area and the observed flow rate at the observation point. Then, it estimates the flow rate at any location on the basis of the water part proportion relating to the location in the water area and the flow rate relation formula.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a technology related to the flow rate of rivers and the like. More specifically, it relates to a flow rate estimation system that can estimate the flow rate at any location based on the flow rate observed at an observation point.

Background Art

[0002] It is beneficial to grasp the amount of water (flow rate) flowing in a river. Especially when floods such as heavy rain are predicted, it becomes extremely important to grasp the river flow rate. For observing the flow rate during a flood, observation using a float has been the basis for over 100 years. This float observation is a method of obtaining the flow velocity by observing the time required for a float dropped into the river to flow down a predetermined distance, and grasping the flow rate by multiplying the flow velocity by the cross-sectional area of the river (the water passage part). And at least five observers are required to conduct float observation, that is, a lot of labor has been required.

[0003] On the other hand, in cases where it is difficult to dispatch many observers, such as rivers in mountainous areas, it is common to observe the river flow rate by the cross-section measurement method. In the cross-section measurement method, the river cross-section is measured at intervals of several centimeters, and thus at least two to three observers are required, and the time required for observation at one point is 15 to 30 minutes. That is, also when grasping the river flow rate by the cross-section measurement method, a lot of labor has been required as in the case of float observation.

[0004] It is also conceivable to directly measure the flow rate using measuring equipment without relying on float observation or the cross-section measurement method. However, it is dangerous to measure with measuring equipment during a flood, and even if the measuring equipment is installed permanently, there is a risk of damage or missing measurement, so it cannot be said to be a practical method.

[0005] Therefore, in recent years, attempts have been made to install cameras or video cameras at notable positions in rivers and to grasp river flow rates based on the images or videos obtained. For example, in Patent Document 1, a technique is proposed in which a camera is installed at a monitoring point, water levels are observed at two locations, upstream and downstream, and the water level at the observation point is estimated based on these observed values and the camera images.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Hitherto, in order to grasp river flow rates, information has been obtained at the point of interest, such as observing the speed of a float at the point where the flow rate is to be grasped, or using the image of a camera permanently installed at that point of interest as in Patent Document 1. That is, the conventional technology has been obtaining river flow rates on the premise that the point of interest has been determined in advance. However, water areas such as rivers and marshes flow over a wide range, and it may not be possible to determine the point of interest in advance. In particular, considering that changes in the flow rate on the upstream side affect the downstream side, it is extremely beneficial to grasp the flow rate on the upstream side. However, there are also deep mountainous areas where people cannot enter upstream, and it is not realistic to set such places as the point of interest.

[0008] The problem of the present invention is to solve the conventional problems, that is, to provide a flow rate estimation system capable of estimating the flow rate at an arbitrary point in a water area.

Means for Solving the Problems

[0009] The invention of the present application focuses on the fact that it virtually sets the maximum area considered as a water area, obtains the area ratio of the water part in the maximum area, and further sets a function representing the relationship between the area ratio and the flow rate obtained at an observable point, and then estimates the flow rate at an arbitrary point. It is an invention made based on an idea that has never existed in the past.

[0010] The flow rate estimation system of the invention of the present application is a system for estimating the flow rate at an arbitrary location in a water area set in a target range, and is provided with a water part area setting means, a maximum width length extraction means, a region setting means, a water part ratio calculation means, and a relational expression setting means. Among these, the water part area setting means is a means for setting a small area corresponding to the water part as the "water part area" by comparing a small area (an area obtained by dividing the target range into a plurality of areas in a planar manner) with the water area. The maximum width length extraction means is a means for obtaining the "water area width length" based on the number of water part areas arranged in a direction perpendicular to the axis set along the water flow of the water area, and extracting the "maximum width length" which is the maximum water area width length in the water area. The region setting means is a means for setting an "entire region" in which the maximum width length is continuous in the direction of the axis, and setting a "divided region" obtained by dividing the entire region at each unit axis length determined in advance along the direction of the axis. The water part ratio calculation means is a means for calculating the "water part ratio" which is the area ratio occupied by the water part area in the divided region, and the relational expression setting means is a means for setting a "flow rate relational expression" indicating the relationship between the water part ratio of the divided region related to the observation point where the observed flow rate is obtained in the water area and the observed flow rate at the observation point. Then, the flow rate at an arbitrary location is estimated based on the water part ratio related to an arbitrary location in the water area and the flow rate relational expression.

[0011] The flow rate estimation system of the invention of the present application can also set a flow rate relational expression based on two or more sets of water part ratios and observed flow rates. In this case, observation points are provided in two or more different divided regions respectively.

[0012] The flow rate estimation system of the present invention can also be further provided with a water area setting means. This water area setting means is a means for setting a water area in a target range using the acquired water area information and a three-dimensional terrain model. The water area information is a vegetation index, and the three-dimensional terrain model is composed of small areas. The water area setting means sets the water area based on the vegetation index and the water line obtained from the three-dimensional terrain model.

[0013] The flow rate estimation system of the present invention can be further provided with a water area setting means and can set the water area using an image including the water area as the water area information. In this case, the water area setting means sets the water area based on the water line obtained from an aerial photograph or a satellite image and the three-dimensional terrain model.

[0014] The flow rate estimation system of the present invention can also compare the flow rates at two times at any location. In this case, the water area setting means sets the water areas at the two times based on the water area information acquired at the two times. Further, the water area region setting means sets a water area region related to the water areas at each of the two times, the maximum width length extraction means extracts the maximum width length related to the water areas at each of the two times, the region setting means sets a divided region related to the water areas at each of the two times, the water area ratio calculation means calculates the water area ratio of the divided regions related to the water areas at each of the two times, and the relational expression setting means sets a flow rate relational expression based on the water area ratio related to the water areas at each of the two times and the observed flow rate at each of the two times. When a plurality of information with higher time resolution is obtained, more detailed time series changes can also be tracked.

Effect of the Invention

[0015] The flow rate estimation system of the present invention has the following effects. (1) It is possible to grasp the flow rate not only at a specific observation point but also at a desired location within the set water area. (2) It is possible to grasp the flow rate without going to the site, such as observing a float, measuring a cross section, or installing a camera. (3) For example, by grasping the change in the upstream flow rate, it is possible to predict the occurrence of disasters such as floods. As a result, appropriate measures can be taken to suppress the damage.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0017] An example of an embodiment of the flow rate estimation system of the present invention will be described with reference to the drawings. The flow rate estimation system of the present invention can estimate the flow rate at any location in a "water area" such as a river or a marsh. For the sake of convenience, an example will be described here assuming that this water area is a "river".

[0018] FIG. 1 is a block diagram showing the main configuration of the flow rate estimation system 100 of the present invention. As shown in this figure, the flow rate estimation system 100 of the present invention includes a water area region setting means 101, a maximum width length extraction means 102, a region setting means 103, a water area ratio calculation means 104, and a relational expression setting means 105, and can further include a water area setting means 106, a 3D terrain model storage means 107, a water area information storage means 108, an observed flow rate storage means 109, and a flow rate relational expression storage means 110.

[0019] The water area setting means 101, maximum width length extraction means 102, area setting means 103, water area ratio calculation means 104, relational expression setting means 105, and water area setting means 106 that constitute the flow rate estimation system 100 of the present invention can be manufactured as dedicated ones, or a general-purpose computer device can also be used. That is, by causing the computer device to execute arithmetic processing according to a predetermined program, the processing of various means is performed. This computer device includes a processor such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit), a memory such as a ROM or RAM, and some also include input means such as a mouse and keyboard and a display, and can be configured by, for example, a personal computer (PC) or a server.

[0020] In addition, the 3D terrain model storage means 107, water area information storage means 108, observed flow rate storage means 109, and flow rate relational expression storage means 110 can use the storage device of a general-purpose computer (for example, a personal computer), or can be constructed in a database server. When constructing in a database server, it can be placed in a local network (LAN: Local Area Network), or can be a cloud server stored via the Internet.

[0021] Hereinafter, each main element constituting the flow rate estimation system 100 will be described in detail.

[0022] (Water area setting means) The water area setting means 106 is a means for setting a river (water area) in a target range such as a predetermined mountainous area (hereinafter simply referred to as "target range"). Therefore, in a case where a river is set in advance in the target range, the flow rate estimation system 100 does not necessarily need to include the water area setting means 106.

[0023] When setting a river, various information indicating that it is a river (hereinafter referred to as "water area information") can be used. For example, as this water area information, a vegetation index typified by the Normalized Difference Vegetation Index (NDVI) can be cited. It is known that the vegetation index obtained from satellite images shows negative values at positions corresponding to water areas, and the range where the vegetation index shows negative values can be automatically set as a river.

[0024] Also, as water area information, an image containing a water area such as an aerial photograph or a satellite image (hereinafter referred to as "water area image") can be used. In this case, a river may be set based on the pixel value (color information) of the water area image. For example, while the operator visually observes the water area image displayed on the display, an operation using a pointing device (such as a mouse, touch panel, pen tablet, touch pad, track pad, track ball, etc.) or a keyboard as the water area setting means 106 is performed, so that the river is set manually. Alternatively, teacher data can be created from the water area image, and a learning model obtained by machine learning (for example, deep learning) of the teacher data can be used, that is, the river can be set automatically.

[0025] Furthermore, as water area information, a "backscattering intensity image" showing the intensity of backscattering obtained by Synthetic Aperture Radar (SAR) in black and white can also be used. Also, a "near-infrared image" obtained by an optical sensor capable of observing visible near-infrared can be used, and a "thermal image" obtained by a sensor capable of observing thermal infrared can also be used.

[0026] If a river is set only based on water area information, it is conceivable that an area that is not originally a river may be set as a river. Therefore, it is advisable to set a river with reference to the "fall line" obtained from a three-dimensional terrain model such as a DEM (Digital Elevation Model). According to this fall line, a valley terrain can be identified, so among the areas that are regarded as "river candidates" based on the water area information, those that correspond to the valley terrain are determined as rivers. Note that various types of information can be used as long as it can identify the valley terrain, not limited to the fall line.

[0027] (Water area setting means) The water area setting means 101 is a means for assigning classification information to each small area by comparing a "small area (so-called mesh)" obtained by dividing the target area into a plurality of parts in a plane with a river set in advance. Specifically, for example, small areas constituting a three-dimensional terrain model are classified into small areas constituting a river (hereinafter referred to as "water areas") and small areas that are not rivers (hereinafter referred to as "non-water areas"). FIG. 2 is a plan view schematically showing a river set based on a plurality of water areas. As shown in this figure, an "axis" is set for a river along the water flow from upstream to downstream. For the sake of convenience, here, the direction of the axis is referred to as the "axis direction", and the horizontal direction perpendicular to this axis is referred to as the "width direction".

[0028] (Maximum width length extraction means) The maximum width length extraction means 102 is a means for obtaining the "water area width length" based on the number of water area regions arranged in the width direction and extracting, as the "maximum width length", the water area width length that shows the maximum value when the entire river is viewed. The small regions have a known planar dimension such as 5 m × 5 m in advance. Therefore, the water area width length can be obtained by multiplying the number of water area regions arranged in the width direction by the unit length (for example, 5 m). In the example of FIG. 2, the small region is set with a planar dimension of 5 m × 5 m. Therefore, the water area width length of the uppermost stream is obtained as 20 m (5 m × 4 pieces), and the water area width length of the lowermost stream is obtained as 70 m (5 m × 14 pieces). And the maximum water area width length in the entire river is 80 m (5 m × 16 pieces). That is, the maximum width length extraction means 102 extracts 80 m as the maximum width length.

[0029] (Region setting means) The region setting means 103 is a means for setting an "entire region" and a "divided region" based on the river. Hereinafter, the procedure for the region setting means 103 to set the entire region and the divided region will be described in detail with reference to FIG. 3. First, the region setting means 103 sets, as the entire region, a range in which the maximum width length extracted by the maximum width length extraction means 102 is continuous in the axial direction. For example, in FIG. 3, since the maximum width length is 80 m (5 m × 16 pieces) and the length of the axis of the entire river is 120 m (5 m × 24 pieces), the region setting means 103 sets 80 m × 120 m (16 pieces × 24 pieces) as the entire region. Next, the region setting means 103 sets divided regions by dividing the entire region for each "unit axial length" determined in advance along the axial direction. For example, in FIG. 3, since the unit axial length is set to 20 m (5 m × 4 pieces), six divided regions A to F are set.

[0030] (Water area ratio calculation means) The water area ratio calculation means 104 is a means for obtaining the "water area ratio" for each divided region. Specifically, the area ratio occupied by the water area region in the divided region is calculated as the water area ratio. As described above, the planar dimension of the small region is known in advance. Therefore, the unit area (for example, 25 m 2By multiplying by (), a predetermined area can be obtained. For example, in the case of Fig. 3, the areas of the divided regions are all 1,600 m 2 (25 m 2 × 64 pieces), and the area of the water area in the divided region A is 475 m 2 (25 m 2 × 19 pieces). Therefore, the water area ratio calculating means 104 calculates the water area ratio related to the divided region A as 0.30 (475 m 2 ÷ 1,600 m 2 ).

[0031] (Relational expression setting means) The relational expression setting means 105 is a means for setting a "flow rate relational expression" showing the relationship between the water area ratio and the flow rate of the river. When setting the flow rate relational expression, the actual value of the flow rate actually observed (hereinafter referred to as "observed flow rate") is used. Then, using a combination (hereinafter referred to as "data set") consisting of the water area ratio of the divided region including the point where the observed flow rate was obtained (hereinafter referred to as "observation point") and the observed flow rate related to that observation point, more specifically, a flow rate relational expression with the water area ratio as the explanatory variable and the observed flow rate as the objective function is set.

[0032] The relational expression setting means 105 can set a flow rate relational expression based on a set of data sets (water area ratio, observed flow rate), or can also set a flow rate relational expression based on two or more sets of data sets. When using two or more sets of data sets, it is desirable to provide observation points in two or more different divided regions. For example, in Fig. 3, one observation point is provided in each of the divided regions D to F.

[0033] When setting based on a set of datasets, the flow rate relational expression can be set as a linear expression (for example, a directly proportional expression). On the other hand, when setting based on two or more sets of datasets, in addition to the linear expression, it can also be set as a quadratic expression, a cubic expression, or even a higher-order expression according to the number of datasets. Also, in the case of using two or more sets of datasets, the flow rate relational expression may not be uniquely determined. In that case, it is advisable to set the flow rate relational expression using the least squares method or the like. The flow rate relational expression set by the relational expression setting means 105 is stored in the flow rate relational expression storage means 110 (Fig. 1).

[0034] (Processing flow) Hereinafter, with reference to Fig. 4, the main processing of the flow rate estimation system 100 will be described in detail. Fig. 4 is a flowchart showing an example of the flow of the main processing of the flow rate estimation system 100, where the processing to be executed is shown in the central column, the things required for that processing are shown in the left column, and the things resulting from that processing are shown in the right column.

[0035] To estimate the flow rate of a river by the flow rate estimation system 100, first, as shown in Fig. 4, the river (water area) is set using the water area setting means 106 (Step 201 in Fig. 4). At this time, as already described, the river is set based on the three-dimensional terrain model (especially the waterline) read from the 3D terrain model storage means 107 (Fig. 1) and the "water area information (vegetation index and water area image)" read from the water area information storage means 108 (Fig. 1). Also, in the case where a river is set in advance in the target range, the processing of setting the river (water area) can be omitted.

[0036] When the river is set, each small area is classified by the water area setting means 101 into either a "water area" or a "non-water area" (Step 202 in Fig. 4). Next, the "water area width length" is obtained and the "maximum width length" is extracted by the maximum width length extraction means 102. When the maximum width length is extracted, the "entire area" is set by the area setting means 103 (Step 203 in Fig. 4), and the "divided area" is set (Step 204 in Fig. 4).

[0037] When the division area is set, the "water part ratio" is obtained for each division area by the water part ratio calculation means 104 (Step 205 in FIG. 4). Next, the "flow rate relational expression" is set by the relational expression setting means 105 (Step 206 in FIG. 4). At this time, as described above, the relational expression setting means 105 sets the flow rate relational expression based on the observed flow rate read from the observed flow rate storage means 109 (FIG. 1) and the water part ratio related to the observation point. Further, the flow rate relational expression set by the relational expression setting means 105 is stored in the flow rate relational expression storage means 110 (FIG. 1).

[0038] When the processing up to this point is completed, the flow rate at any location in the river (water area) can be calculated. Specifically, when a location for which the flow rate is to be determined (hereinafter referred to as the "designated location") is input, the water part ratio of the division area related to the designated location is read, and the flow rate is calculated by inputting this water part ratio into the flow rate relational expression (Step 207 in FIG. 4).

[0039] When using the flow rate estimation system 100, it is possible to compare the flow rates at two different times in the same location. For example, it is possible to compare the high water period and the low water period in the same year, or to compare the low water periods in different years. By the way, it is conceivable that the range of the river (that is, the water area) is different at different times. Therefore, it is advisable to set the river (water area) for each time period to be compared and then calculate the flow rate for each time period. Specifically, the water area setting means 106 is used to set the rivers for the two time periods based on the water section information acquired at the two time periods, the water section area setting means 101 sets the water section areas related to the rivers for the two time periods, the maximum width length extraction means 102 extracts the maximum width length related to the rivers for the two time periods, the area setting means 103 sets the divided areas related to the water areas for the two time periods, the water section ratio calculation means 104 calculates the water section ratio of the divided areas related to the rivers for the two time periods, and the relational expression setting means 105 sets the flow rate relational expression based on the water section ratio related to the rivers for the two time periods and the observed flow rate for the two time periods. Incidentally, when more information with higher time resolution is obtained, it is also possible to track more detailed time series changes. Also, when the rivers (that is, the water areas) are set for a plurality of time periods, it is advisable to set the area related to the time period with the highest flow rate as the river.

Industrial Applicability

[0040] The flow rate estimation system of the present invention can be used for various water areas such as rivers and marshes. Considering that the present invention can quickly predict water disasters associated with water areas such as floods, and as a result, can protect many residents from disasters, it can be said that the present invention is not only industrially applicable but also expected to make a great social contribution.

Explanation of Reference Numerals

[0041] 100 Flow rate estimation system 101 Water section area setting means 102 Maximum width length extraction means 103 Area setting means 104 Water section ratio calculation means 105 Relational expression setting means 106 Water area setting means 107 3D terrain model storage means 108 Water part information storage means 109 Observed flow rate storage means 110 Flow rate relational expression storage means

Claims

1. A system for estimating the flow rate at any location in a water area set within a target range, comprising: a water area region setting means for setting, as a water area region, a small region that corresponds to a water part by comparing a small region obtained by planar division of the target range into a plurality of parts with the water area; a maximum width length extraction means for obtaining a water area width length based on the number of the water area regions arranged in a direction perpendicular to an axis set along the water flow of the water area, and extracting a maximum width length that is the maximum of the water area width lengths in the water area; a region setting means for setting an entire region in which the maximum width length is continuous in the direction of the axis, and setting a divided region obtained by dividing the entire region at predetermined unit axis lengths along the direction of the axis; a water part ratio calculation means for calculating a water part ratio that is the area ratio occupied by the water area region in the divided region; a relational expression setting means for setting a flow rate relational expression showing the relationship between the water part ratio of the divided region related to an observation point where an observed flow rate is obtained in the water area and the observed flow rate at the observation point; and estimating the flow rate at any location based on the water part ratio at any location in the water area and the flow rate relational expression. A flow rate estimation system characterized by the above.

2. The observation points are respectively provided in two or more different divided regions, and the relational expression setting means sets the flow rate relational expression based on the water part ratios and the observed flow rates related to two or more of the observation points. The flow rate estimation system according to claim 1, characterized by the above.

3. further comprising a water area setting means for setting the water area in the target range using the acquired water part information and a three-dimensional terrain model, wherein the water part information is a vegetation index, the three-dimensional terrain model is composed of the small regions, and the water area setting means sets the water area based on the vegetation index and a water line obtained from the three-dimensional terrain model. The flow rate estimation system according to claim 1, characterized by the above.

4. further comprising a water area setting means for setting the water area in the target range using the acquired water part information and a three-dimensional terrain model, wherein the water part information is a water area image including the water area, the three-dimensional terrain model is composed of the small regions, and the water area setting means sets the water area based on the water area image and a water line obtained from the three-dimensional terrain model. The flow rate estimation system according to claim 1, characterized by the above.

5. The water area setting means sets the water area at the two times based on the water part information acquired at the two times. The water part area setting means sets the water part area related to the water area for each of the two times. The maximum width length extraction means extracts the maximum width length related to the water area for each of the two times. The area setting means sets the divided area related to the water area for each of the two times. The water part ratio calculation means calculates the water part ratio of the divided area related to the water area for each of the two times. The relational expression setting means sets the flow rate relational expression based on the water part ratio related to the water area for each of the two times and the observed flow rate for each of the two times. It is possible to compare the flow rates at the two times at any location. The flow rate estimation system according to claim 3 or claim 4, characterized in that.

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