Water level management method, water level management device, and control program

Abstract

To allow for calculation of pre-release water levels several days before rainfall start on flood control use of a reservoir.SOLUTION: A water level management method according to one embodiment is a reservoir water level management method executed by a device (10). The water level management method includes the steps of: estimating a recoverable water volume for each arbitrary time unit in the reservoir according to a predicted rainfall amount for each arbitrary time unit around a target reservoir; estimating a total recoverable water volume for an arbitrary accumulation period by integrating the recoverable water volume for each time unit by the arbitrary accumulation period; and calculating, as a pre-release water level, a water level difference between (i) the observed water level at the start of pre-release and (ii) the water level corresponding to a water volume obtained by subtracting the recoverable water volume during the accumulation period from the water volume corresponding to an arbitrarily set management water level of the reservoir, by referring to information indicative of the relationship between the reservoir's water volume and water level.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water level management method, a water level management device, and a control program. [Background technology]

[0002] When using agricultural reservoirs for flood control, "low water level management" is implemented to ensure free capacity for storing rainwater during non-irrigation periods by constantly lowering the water level during predetermined periods in order to store rainwater during heavy rains. However, free capacity is generally not secured for the rainy season and summer typhoons that overlap with the irrigation period, as securing irrigation water takes priority. In order to provide free capacity during the irrigation period, it is necessary to estimate the amount of water that will be restored by heavy rain and release water in advance in an amount commensurate with the restored amount so as not to interfere with the securing of irrigation water.

[0003] Patent Document 1 discloses a reservoir dynamics monitoring system that uses the current water level data and rainfall data of the reservoir to quickly predict reservoir collapse and drought. Patent Document 2 discloses a water level monitoring system that predicts slides and overflows in the reservoir embankment and detects signs of collapse from acquired water level, water quality, and weather information. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-174983 A [Patent Document 2] International Publication WO2021 / 229789A1 Summary of the Invention [Problem to be solved by the invention]

[0005] Unlike dams, water management at agricultural reservoirs, such as the discharge operation of water intake facilities, is not carried out by specialized engineers but by the farmers who benefit from the reservoir themselves. This makes it difficult to carry out prompt operations based on rainfall and flood inflow forecasts, and to ensure the safety of workers, discharge operations must be completed before rain begins. Furthermore, the discharge facilities are not equipped with gates that can release large amounts of water, so discharge is carried out from water intake facilities for irrigation, or from spillway slits and discharge pipes that are capable of discharging small amounts of water. Therefore, in terms of discharge capacity, discharge operations for advance release must be carried out about 1 to 3 days (24 to 72 hours) before the start of rainfall.

[0006] In view of the above, in order to pre-release a reservoir, it is necessary to calculate the recovery water volume corresponding to the pre-release operation approximately 1 to 3 days (24 to 72 hours) before the start of rainfall and the pre-release water level based on this, rather than predicting the water level corresponding to the short-term forecast rainfall of approximately 1 to 6 hours in the future as in conventional technology.

[0007] However, the above-mentioned conventional techniques have the problem that they are unable to calculate the pre-discharge water level.

[0008] One aspect of the present invention has been made in consideration of the above problems, and aims to enable calculation of advance discharge water levels several days before the start of rainfall in relation to flood control use of reservoirs. [Means for solving the problem]

[0009] In order to solve the above problems, a water level management method according to one embodiment of the present invention is a water level management method for a reservoir executed by an apparatus, and includes the steps of estimating the recovery water storage volume for each unit of time in the reservoir in accordance with the predicted rainfall for each unit of time around the target reservoir, estimating the recovery water storage volume for an arbitrary accumulation period by integrating the recovery water storage volume for each unit of time for the arbitrary accumulation period, and calculating, as a pre-release water level, the water level difference between (1) the observed water level at the start of pre-release and (2) the water level corresponding to the water storage volume obtained by subtracting the recovery water storage volume for the accumulation period from the water storage volume corresponding to the arbitrarily set management water level of the reservoir, by referring to information indicating the correspondence between the water storage volume and water level of the reservoir.

[0010] In order to solve the above problems, a water level management device according to one embodiment of the present invention is a water level management device that performs processing related to the water level of a target reservoir, and is equipped with a control unit that performs the following processes: a process of estimating the recovery water storage volume for each unit of time in the reservoir according to the predicted rainfall for each unit of time around the reservoir; a process of estimating the recovery water storage volume for an arbitrary accumulation period by integrating the recovery water storage volume for each unit of time for the arbitrary accumulation period; and a process of calculating, as a pre-release water level, the water level difference between (1) the observed water level at the start of pre-release and (2) the water level corresponding to the water storage volume obtained by subtracting the recovery water storage volume for the accumulation period from the water storage volume corresponding to the arbitrarily set management water level of the reservoir, by referring to information indicating the correspondence between the water storage volume and water level of the reservoir.

[0011] The water level management device according to each aspect of the present invention may be realized by a computer, and in this case, the control program for the water level management device, which causes the computer to operate as each unit (software element) of the water level management device, and the computer-readable recording medium on which the control program is recorded, are also within the scope of the present invention. The same applies to the discharge device described below. Effect of the Invention

[0012] According to one aspect of the present invention, in relation to the use of a reservoir for flood control, it is possible to calculate the advance discharge water level several days before the start of rainfall. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an example of a block diagram showing a functional configuration of a water level management system. [Diagram 2] 1 is an example of a sequence diagram showing a processing flow of a water level management system. [Diagram 3] FIG. 1 is a diagram for explaining an example of processing of a water level management system. [Figure 4] FIG. 2 is a diagram for explaining the relationship between the amount of water stored in a reservoir and the water level. [Diagram 5] This is an example of a table summarizing the relationship between water depth h1, water surface area A1, and water volume V1. [Figure 6] 1 is an example of a diagram showing the relationship between the amount of rainfall in a series of rainfalls and the amount of restored water storage. [Figure 7] 1 is an example of a table showing the relationship between daily rainfall, restored water storage volume, and an integrated value of the restored water storage volume. [Figure 8] 1 is an example of a table showing the relationship between the predicted water storage volume and the predicted water level for each day. [Figure 9] 1 is an example of a diagram showing the relationship between the predicted water level transition and the management water level. [Figure 10] 13 is an example of a table showing the relationship between the predicted water volume and predicted water level for each day, assuming that no advance release is performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, one embodiment of the present invention will be described in detail.

[0015] [1. Example of water level control system 1 configuration] Fig. 1 is an example of a block diagram showing the functional configuration of a water level control system 1 according to the present disclosure. The water level control system 1 is a system for balancing flood control and irrigation in the area around a reservoir under management, and is a system for realizing appropriate release of water according to predicted rainfall. Note that the reservoir in the present disclosure is not limited to artificial ones, but may include naturally formed lakes and marshes.

[0016] As shown in FIG. 1, the water level control system 1 includes a water level control device 10 and a discharge device 21 installed in a reservoir 20.

[0017] The water level management device 10 is a device for managing the water level of a reservoir, and is equipped with a control unit 11, a memory unit 15, a communication unit 16, an input unit 17, and an output unit 18.

[0018] The control unit 11 is a control device that controls the entire water level management device 10, and includes a data acquisition unit 12 and a discharge control unit 13. The control unit 11 also performs various estimation processes and calculation processes, which will be described later, and issues instructions to the discharge device 21.

[0019] The data acquisition unit 12 acquires information indicating the predicted amount of rainfall in the vicinity of the reservoir 20. For example, the data acquisition unit 12 may acquire the information indicating the predicted amount of rainfall from the Internet via the communication unit 16.

[0020] In addition, the data acquisition unit 12 may acquire rainfall forecast data that provides a large number of data (51 types for Japan GPV data (high resolution)) with different calculation initial conditions for the same location and period over a long period of time (264 hours ahead), such as the ensemble rainfall forecast data distributed by the Japan Meteorological Agency, "Japan GPV data (high resolution)."

[0021] Furthermore, the data acquisition unit 12 acquires information indicating the water level of the reservoir 20 from the discharge device 21 via the communication unit 16. The data acquisition unit 12 may acquire information regarding the water level of the reservoir from the Internet via the communication unit 16. Furthermore, the information stored in the memory unit 15 may be information acquired by the data acquisition unit 12 in advance.

[0022] Memory unit 15 is a storage device that stores various information, for example, position data and cross-sectional shape data of reservoir 20, and information indicating a correspondence relationship between the amount of water stored and the water level in reservoir 20 based on the cross-sectional shape data. Here, the cross-sectional shape data may include three-dimensional data indicating the shape of reservoir 20, in addition to data indicating the cross-sectional shape of reservoir 20 on a plane at a specific position. Furthermore, the information indicating the correspondence relationship may be generated by control unit 11 with reference to the cross-sectional shape data of reservoir 20.

[0023] The communication unit 16 is an interface that performs communication processing with external devices such as the discharge device 21 based on the control of the control unit 11.

[0024] The input unit 17 is a member that allows the user to input information to the water level management system 1, and may be realized as, for example, a keyboard or other buttons, or a mouse. The input unit 17 may also be a remote control or controller that is separate from the main body of the water level management system 1. The user may set the time unit for predicting the amount of rainfall, etc., via the input unit 17, or may input instructions to the water level management device 10.

[0025] The output unit 18 outputs the calculation results and the like by the control unit 11. In many cases, the output unit 18 is a display that displays images and text. Note that the output unit 18 may be a smartphone, tablet, personal computer, or the like that is separate from the water level control system 1 main body.

[0026] The discharge device 21 is a device for executing discharge in a reservoir 20 to be managed, and includes a control unit 23, a memory unit 25, a communication unit 24, a sensor unit 26, and a discharge unit 27.

[0027] The control unit 23 is a control device that controls the entire discharge device 21 .

[0028] The storage unit 25 is a storage device that stores various information, and stores, for example, information transmitted from the water level management device 10 at least temporarily.

[0029] The communication unit 24 is an interface that performs communication processing with external devices such as the water level management device 10 based on the control by the control unit 23.

[0030] The sensor unit 26 is a sensor that senses an observed water level, which is the water level of the reservoir 20 at a certain observation point in time.

[0031] The discharge unit 27 is a physical mechanism for discharging water from the reservoir 20. The discharge unit 27 may include a spillway slit and a discharge pipe, as well as a gate and an intake hole that constitute the intake and discharge facility. The discharge unit 27 can be switched between a state in which the discharge is performed from the reservoir 20 and a state in which the discharge from the reservoir 20 is blocked.

[0032] It is not essential that the water level control device 10 and the discharge device 21 are realized as separate devices, and they may be realized as a single device. Also, a single water level control device 10 may be configured to execute processing for each of the discharge devices 21 provided in each of the multiple reservoirs 20.

[0033] [2. Example of processing by water level control system 1] Next, an example of the flow of processing executed by the water level control system 1 will be described. Fig. 2 is an example of a sequence diagram showing the flow of processing according to this example. Fig. 3 is a diagram for explaining the processing according to this example.

[0034] In S101 (step S101), the data acquisition unit 12 of the water level management device 10 acquires the predicted rainfall amount for each arbitrary time unit around the reservoir 20. In the example of FIG. 3, the predicted rainfall amount acquired by the data acquisition unit 12 is the rainfall amount for each day from the end of the third day (72 hours) after the lead time from the current day 0 (0 hours) to the end of the fifth day (144 hours) three days ahead, which is the accumulation period. The lead time means the total time required for the start of the discharge process of the reservoir 20 and the time required for the discharge itself, and in the example of FIG. 3, it is three days before the rainfall is predicted to start. The arbitrary time unit described above may be a time unit previously set by the user via the input unit 17, or may be a time unit specified as a default, for example, one day. The predicted rainfall amount for each time unit may be different from each other in each time unit. In the example of Fig. 3, the predicted rainfall from the end of the third day (72 hours) to the end of the fifth day (144 hours) may be different for each day. Also, the integration period may include a time period with no rainfall.

[0035] Furthermore, in each step after step S101, the output unit 18 may output, for example, information acquired by the control unit 11, as well as estimation results and calculation results, etc., as the state or processing results of the water level management device 10. In addition, the control unit 11 may acquire information indicating the state or processing results of the discharge device 21 from the discharge device 21 via the communication unit 16, and the output unit 18 may output the information.

[0036] In S102, the control unit 11 estimates the recovery water storage volume in the reservoir 20 for each time unit from the acquired predicted rainfall. Here, the recovery water storage volume is the inflow of rainwater based on the predicted rainfall, and is the water storage volume of the reservoir 20 restored by inflow from the basin (catchment area) of the reservoir 20. The recovery water storage volume is the volume or weight of rainwater that is the total of only the inflow into the reservoir 20 due to rainfall during a period, without considering discharge from the spillway slits of the discharge unit 27 or water intake. The control unit 11 may estimate the recovery water storage volume from, for example, the water surface area of ​​the reservoir 20 and the predicted rainfall, or may be configured to estimate the recovery water storage volume by referring to information or an estimation formula that is information stored in advance in the storage unit 15 and indicates the correspondence between the predicted rainfall and the recovery water storage volume of the reservoir 20. The calculation of the recovery water storage volume is not limited to a specific method, and a method using a statistical model or a physical model, or a method using AI may be used.

[0037] In S103, the control unit 11 estimates the restoration water storage volume for an arbitrary integrated period by integrating the restoration water storage volume for each time unit for the arbitrary integrated period. In the example of Fig. 3, the integrated period is three days from the end of the third day (72 hours) to the end of the fifth day (144 hours). The arbitrary integrated period may be a period preset by the user via the input unit 17, or may be a period specified as a default.

[0038] In S104, the control unit 11 transmits to the discharge device 21 via the communication unit 16 a request to transmit the observed water level, which is the water level of the reservoir 20 at the current time.

[0039] In S105, the sensor unit 26 of the discharge device 21 senses the observed water level of the reservoir 20, and the control unit 23 transmits information indicating the observed water level to the water level management device 10 via the communication unit 24.

[0040] In S106, the control unit 11 calculates the water volume corresponding to an arbitrary management water level input via the input unit 17. Next, the control unit 11 obtains the water volume by subtracting the integrated value of the recovery water volume, i.e., the recovery water volume for the integration period, from the water volume corresponding to the management water level, and calculates the water level difference between the water level corresponding to the subtracted water volume and the observed water level as the pre-discharge water level. Here, the management water level is the water level targeted in the water storage management.

[0041] The above-mentioned managed water level may be input to the input unit 17 and stored in the memory unit 15 at any timing, or the value of the observed water level may be used. When calculating the water volume from the water level, or when calculating the water level from the water volume, the control unit 11 refers to information derived in advance that indicates the correspondence relationship between the water volume and the water level. In other words, the information indicating the correspondence relationship is information for mutually converting the water volume and the water level that correspond to the same amount of water. Details of the information indicating the correspondence relationship will be described later.

[0042] The pre-discharge water level is a target water level difference in the discharge performed during the lead time. From another perspective, the discharge device 21 discharges water into the reservoir until the water level difference before and after discharge reaches the pre-discharge water level during the lead time.

[0043] In S107, the control unit 11 judges whether or not the water level after the discharge of the pre-discharge water level calculated in S106 is below the lower limit water level required for irrigation of the area around the reservoir 20. When the control unit 11 judges that the water level after the discharge is below the required lower limit water level (S107: YES), in S108, the control unit 11 sets the water level difference when discharging to the required lower limit water level as the pre-discharge water level to be used in the subsequent processing. This means that the water level is set so as not to fall below a predetermined water level required for irrigation even after the discharge of the pre-discharge water level. This is to ensure that the minimum amount of water required can be secured even if, for example, the prediction is wrong and there is no rainfall. In addition, when the control unit 11 judges that the water level after the discharge of the pre-discharge water level calculated in S106 is not below the required water level (S107: NO), the control unit 11 does not update the value of the pre-discharge water level and subsequently executes the processing of S109.

[0044] In S109, the discharge control unit 13 transmits an instruction to the discharge device 21 via the communication unit 16 to discharge the amount of water equivalent to the pre-discharge water level before rainfall. In other words, following the step of calculating the pre-discharge water level, the control unit 11 automatically outputs a signal to the discharge device 21 to instruct the discharge device 21 to complete the discharge of the amount of water equivalent to the pre-discharge water level in the reservoir 20 before rainfall.

[0045] In S110, the control unit 23 of the discharge device 21 controls the discharge unit 27 so that discharge is completed before rainfall occurs, and discharges the amount of water in the reservoir 20 up to the pre-discharge water level.

[0046] As a result, the water level of the reservoir 20 drops from the observed water level by the pre-discharge water level during the lead time, and then due to rainfall during the accumulation period, the water level rises by a water level range corresponding to the recovery water storage volume during the accumulation period, and recovers to approximately the control water level set in S106.

[0047] The above describes the reservoir water level management method executed by the water level management device 10. As described above, the water level management method includes a step of estimating the restoration water storage volume for each time unit, a step of estimating the restoration water storage volume for the accumulation period, and a step of calculating the pre-discharge water level based on the observed water level, the arbitrarily set management water level, and the restoration water storage volume for the accumulation period.

[0048] According to the water level management method, in relation to the use of a reservoir for flood control, it is possible to calculate the pre-discharge water level several days before the start of rainfall, which contributes to achieving both flood control and irrigation in the area around the reservoir.

[0049] In addition, the water level management method in the conventional technology was configured to predict the amount of water storage to be restored for a short period of time, within approximately six hours from the time of prediction, in order to prevent the reservoir from bursting, and to calculate the amount of water level reduction required to prevent the reservoir from bursting, by calculating the amount of water storage to be restored due to successive rainfalls.

[0050] On the other hand, the water level management method disclosed herein estimates the amount of water storage that is expected to be restored through continuous or intermittent rainfall during an arbitrarily set period of about 1 to 11 days (24 to 264 hours) into the future, which is within the period during which rainfall forecast data is distributed, not limited to a single series of rainfall, and can calculate the pre-discharge water level corresponding to the rainwater storage capacity that is compatible with irrigation (the capacity to store water flowing into the reservoir to strengthen flood control functions).

[0051] 3. Modifications In S106 of FIG. 2, the pre-discharge water level may be calculated by the following procedure.

[0052] (1) By referring to information showing the correspondence between the water volume and water level of the reservoir 20, the recovery water level for the integrated period is calculated from the recovery water volume for the integrated period and the observed water level described above. Here, the recovery water level for the integrated period is the difference in water level between the start of the integrated period (day 0) and the end of the integrated period. Note that if the cross-sectional area of ​​the reservoir 20 in a plane parallel to the reservoir bottom is constant regardless of the depth, the recovery water level will be constant regardless of the observed water level, and therefore there is no need to refer to the observed water level when calculating the recovery water level.

[0053] (2) (i) The water level difference between the observed water level and (ii) the water level obtained by subtracting the recovery water level for the accumulation period from the management water level mentioned above is calculated as the pre-discharge water level.

[0054] [4. Supplementary explanation regarding the processing of the Water Level Control System 1] Next, specific examples will be given to supplement the information showing the correspondence between the water volume and the water level, and the process of calculating the pre-discharge water level, etc. The control unit 11 of the water level management device 10 may perform the process of deriving values ​​using each equation described below.

[0055] FIG. 4 is a diagram for explaining the relationship between the amount of water stored in a reservoir and the water level. In FIG. 4, A0 is the full water area (m 2 ), and A1 is the water surface area (m 2 ) and A2 is the area of ​​the reservoir bottom (m 2 ), h0 indicates the full water depth (m), which is the water level when the reservoir is full, and h1 indicates the current water level (m). V1 indicates the current water volume (m 3 )

[0056] The following formulas 1 to 3 hold between the above-mentioned values. c=(A0-A2) / h0…(Formula 1) A1=c×h1+A2…(Formula 2) V1=(A1+A2)×h1 / 2…(Formula 3) For example, the Somoike Pond in Amida-cho, Takasago City, Hyogo Prefecture has a bottom area of ​​23750 (m 2 ), where the constant c is 462.96. In addition, when calculating the reservoir volume, values ​​related to the reservoir, such as the full water area A0, may be set using the data in the database installed in the reservoir disaster prevention support system operated by the Ministry of Agriculture, Forestry and Fisheries. In addition, if separate survey data for the reservoir is available, that survey data may be used.

[0057] In addition, the full water depth h0 and the pond bottom area A2 may be derived using the embankment height, full water area, and spillway depth values ​​obtained from a database installed in the reservoir disaster prevention support system, as well as the following equations 4 and 5. h0 = (dam height - spillway depth) x 0.75...(Equation 4) A2=A0×0.6…(Formula 5) Here, the sources of the above formulas 4 and 5 are the following research papers. Hiroshi Yoshisako and Shigeo Ogawa (2009): Creating flood control capacity by converting water utilization capacity in irrigation ponds - A study on Rokudo Pond in Higashi-Hiroshima City -, Systems Agriculture, 25(1), pp.63-70 FIG. 5 is (a part of) a table summarizing the relationship between water depth h1, water surface area A1, and water volume V1 for the above-mentioned Somo Pond. Based on each value of h1 for each increment and each value of water volume V1 illustrated in FIG. 5, a polynomial that serves as an approximate curve with good reproducibility for calculating one of V1 and h1 from the other is derived using an analysis tool in spreadsheet software Microsoft Excel (registered trademark) or the like. The following formula 6 is an example of the polynomial. The right-hand side of formula 6 is a quintic expression, and a1 to a5 and b are constants. Moreover, formula 6 is an example of information indicating the correspondence relationship between the water volume and the water level in reservoir 20, as described above. h1=a1×V1+a2×V1 2 +a3×V1 3 +a4×V1 4 +a5×V1 5 +b…(Formula 6) In the example of the Somoike pond, the values ​​of a1 to a5 and b are as follows: a1: 4.21052E-05 a2:-1.72780E-11 a3: 1.41377E-17 a4:-1.38298E-23 a5: 1.09796E-29 b : 4.32856E-08 Next, a regression equation showing the relationship between rainfall per hour and restored water storage volume is derived from the relationship between the restored water storage volume, which is calculated by converting the water level in the observation data into water storage volume using Equation 6, and the total rainfall volume during a series of rainfalls in the observation data.

[0058] Fig. 6 is an example of a diagram showing the relationship between the rainfall amount of a series of rainfalls and the restored water storage volume. A straight line 31 in Fig. 6 shows an example of the regression equation passing through the origin, and can be used in estimating the restored water storage volume for each time unit in S102 in Fig. 2.

[0059] Next, the derived regression equation is used to calculate the restored water storage volume from the predicted rainfall for each hourly unit. Figure 7 is an example of a table showing the relationship between daily rainfall, restored water storage volume, and the integrated value of restored water storage volume. Here, daily rainfall refers to the predicted rainfall volume for each day, which is an hourly unit. In addition, when the lead time is one day (24 hours), the integrated value of restored water storage volume at the point where 11 days have passed (264 hours have passed) can be calculated as the sum of the restored water storage volumes from the first day (elapsed time 0-24 hours) to the 11th day (elapsed time 240-264 hours). Note that since the first day (elapsed time 0-24 hours) is the lead time, the daily rainfall is 0 mm / day regardless of the actual predicted rainfall amount, and the restored water storage volume is also 0 mm. 3 It becomes / day.

[0060] The table on the right side of Fig. 8 shows the relationship between the predicted water storage volume and the predicted water level for each day. The same table as Fig. 7 is also shown on the left side of Fig. 8 and Fig. 10, which will be described later. Fig. 9 is an example of a diagram showing the relationship between the transition of the predicted water level and the managed water level.

[0061] In the examples of Figures 8 and 9, the managed water level is 2.7 m, which corresponds to the constant full water level. The predicted water level is the water level that would be reached if advance release were performed at 0 days (0 hours) after an accumulation period of 11 days (264 hours) so that the water level would be the managed water level of 2.7 m. The predicted water level is also the water level that corresponds to the predicted water volume. In other words, the predicted water level is the water level that can be calculated from the predicted water volume using Equation 6.

[0062] For example, the predicted water volume after 10 days (240 hours) is 57838.3m 3 ) is the water volume (65812.5m) corresponding to the controlled water level (2.70m) after 11 days (264 hours).3 ) from the recovery water volume (44446.5m) on the 11th day (240-264 hours) 3 ) The predicted water storage volume at 9 days (216 hours) is calculated by subtracting the restored water storage volume on the 10th day from the predicted water storage volume at 10 days (240 hours). Similarly, the predicted water storage volume is calculated up to 0 days (0 hours).

[0063] For example, if the observed water level at 0 days (0 hours) (when pre-release begins) is 2.6m, the predicted water level at the same time is 0.89m, so the pre-release water level is calculated as the difference between these water levels, 1.71m (=2.6m-0.89m).

[0064] In addition, discharging the amount of pre-discharge water level in S107 of FIG. 2 can be said to be discharging water until the observed water level of the reservoir 20 reaches the predicted water level at the point when 0 days have elapsed (0 hours have elapsed).

[0065] The table on the right side of Figure 10 shows the relationship between the predicted water volume and predicted water level for each day, assuming that no advance release is performed. The predicted water volume and predicted water level in the table on the right side of Figure 8 are values ​​assuming that advance release is performed, while the predicted water volume and predicted water level in the table on the right side of Figure 10 are values ​​assuming that advance release is not performed.

[0066] In the table on the right side of Figure 10, for example, the predicted water volume (65812.5 m) after one day (24 hours) has elapsed. 3 ) is the water volume (65812.5m) corresponding to the observed water level (2.70m) at the time of 0 days elapsed (0 hours elapsed). 3 ) on the first day (0 to 24 hours) 3 ) The predicted water storage volume at 2 days (48 hours) is the sum of the predicted water storage volume at 1 day (24 hours) and the restored water storage volume on the second day (24-48 hours). Similarly, the predicted water storage volume is calculated up to 11 days (264 hours).

[0067] [5. Additional Notes] In the sequence diagram of Fig. 2, it is not essential that the processes of S108 and S109 are performed. In addition, even if the water level after the release of the pre-release water level falls below a predetermined water level required for irrigation, the pre-release water level may be set so that rainwater does not overflow from the reservoir 20 after rainfall in the accumulation period.

[0068] This disclosure also includes a case where the discharge from the reservoir 20 is not completed before the start of rainfall, as long as the rainfall does not cause the reservoir 20 to overflow.

[0069] The water level control device 10 may be configured to issue a discharge instruction to the discharge device 21 in response to a user's instruction to the input unit 17. In other words, the present disclosure also includes a configuration in which the water level control device 10 does not automatically issue a discharge instruction to the discharge device 21. In addition, the present disclosure also includes an embodiment in which, in a reservoir in which the discharge device 21 is not installed, the discharge operation is manually performed based on the information displayed on the output unit 18 of the water level control device 10 to control the water level.

[0070] [6. Software implementation example] The functions of the water level control device 10 and the discharge device 21 (hereinafter referred to as the "device") are a program for causing a computer to function as the device, and can be realized by a program for causing a computer to function as each control block of the device.

[0071] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program to realize each function described in each of the above embodiments.

[0072] The program may be non-transitory and may be recorded in one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be provided to the device via any wired or wireless transmission medium.

[0073] In addition, some or all of the functions of each of the control blocks can be realized by a logic circuit. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention. In addition, the functions of each of the control blocks can be realized by, for example, a quantum computer.

[0074] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may be executed by the control device or another device (for example, an edge computer or a cloud server).

[0075] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0076] 1. Water Level Control System 10 Water level control device 11, 23 Control section 12 Data Acquisition Section 13 Discharge Control Section 15, 25 Storage section 16, 24 Communications Department 17 Input section 18 Output section 21 Discharge device 26 Sensor section 27 Discharge Section

Claims

1. A method for managing water levels in a reservoir, the method being carried out by an apparatus comprising the steps of: A step of estimating a recovery water volume in a target reservoir for each unit of time according to a predicted rainfall amount for each unit of time around the target reservoir; A step of estimating the recovery water storage volume for an arbitrary integration period by integrating the recovery water storage volume for each time unit for the arbitrary integration period; A water level management method comprising the steps of: referring to information indicating the correspondence between the water storage volume and water level of the reservoir, and calculating, as the pre-discharge water level, the water level difference between (1) the observed water level at the start of pre-discharge and (2) the water level corresponding to the water storage volume obtained by subtracting the recovery water storage volume for the accumulation period from the water storage volume corresponding to the arbitrarily set management water level of the reservoir.

2. The method further includes a step of calculating a restoration water level for the integrated period corresponding to the restoration water volume for the integrated period by referring to information indicating a correspondence relationship between the water volume and the water level of the reservoir, In the step of calculating the preliminary discharge water level, 2. The water level management method according to claim 1, wherein the pre-discharge water level is calculated as the water level difference between (1) the observed water level and (2) the water level obtained by subtracting the recovery water level for the accumulation period from the management water level.

3. 3. The water level management method according to claim 1, wherein the pre-discharge water level is set so that a water level after the pre-discharge water level is discharged does not fall below a predetermined water level required for irrigation.

4. The water level management method according to claim 1 or 2, further comprising the step of generating information indicating the correspondence by referring to cross-sectional shape data of the reservoir.

5. The water level management method according to claim 1 or 2, further comprising, following the step of calculating the pre-discharge water level, a step of automatically outputting a signal instructing the discharge of the pre-discharge water level to be completed before rainfall occurs.

6. A water level management device for performing processing regarding the water level of a target reservoir, A process of estimating a recovery water volume in the reservoir for each unit of time according to a predicted rainfall amount for each unit of time around the reservoir; A process of estimating a recovery water storage volume for an arbitrary integration period by integrating the recovery water storage volume for each time unit for the arbitrary integration period; A water level management device comprising a control unit that executes a process of calculating, as a pre-discharge water level, the water level difference between (1) the observed water level at the start of pre-discharge and (2) the water level corresponding to the water storage volume obtained by subtracting the recovery water storage volume for the accumulation period from the water storage volume corresponding to the arbitrarily set management water level of the reservoir, by referring to information indicating the correspondence between the water storage volume and water level of the reservoir.

7. A control program for causing a computer to function as the water level management device according to claim 6, the control program causing a computer to function as the control unit.

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