Precipitation amount estimation device, precipitation amount estimation method, and program storage medium

Abstract

To enable provision of information on precipitation amounts in areas where rain gauges are not installed, an acquisition unit of this precipitation amount estimation device uses a soil moisture sensor installed at an estimation target location to acquire, as soil moisture content information, information on soil moisture content that is the content of moisture contained in the soil of the estimation target location. The estimation unit uses information on a change over time in soil moisture content based on the soil moisture content information to estimate the precipitation amount of the estimation target location.

Description

Precipitation estimation device, precipitation estimation method, and program storage medium

[0001] The present invention relates to a technique for estimating precipitation.

[0002] When adjusting the amount of water supplied to a field by irrigation (hereinafter also referred to as the irrigation water supply amount), for example, a crop grower or a field manager (hereinafter, crop growers and field managers will be collectively referred to as field stakeholders) may decide the irrigation water supply amount based on the amount of precipitation in the field. Information on the amount of precipitation in the field is obtained, for example, from information on a rain gauge at a public institution.

[0003] Patent Document 1 (JP 2019-165647 A) discloses a technology for managing the amount of water supplied to a field using drip irrigation. The technology disclosed in Patent Document 1 detects fluctuations in the soil moisture content of each field using sensor data from moisture sensors installed in each field plot, and calculates the amount of water supplied to the field by drip irrigation for each plot using this fluctuation in the soil moisture content.

[0004] Japanese Patent Application Laid-Open No. 2019-165647

[0005] As mentioned above, for example, when determining the amount of irrigation water to be supplied, information from rain gauges of public institutions may be used. In this case, the following concerns arise. Although the installation intervals of rain gauges of public institutions vary depending on the location, they are not densely installed, for example, at intervals of about 20 to 30 kilometers. Therefore, the information from rain gauges that field personnel refer to to obtain information on precipitation in a field may be information from a rain gauge installed more than 10 kilometers away from the field. Because precipitation can vary significantly even a few kilometers away, the precipitation measured by the rain gauge referenced by the field personnel may differ significantly from the actual precipitation in the field. In this case, there is a concern that the difference between the precipitation measured by the referenced rain gauge and the actual precipitation in the field may result in the irrigation water supply being determined to be an amount that deviates from the appropriate amount of irrigation water to be supplied based on the actual precipitation in the field.

[0006] To address these concerns, one option is to install rain gauges in the fields, but this can be difficult due to the cost of purchasing the gauges and the issue of managing them once installed in the fields. Similar issues can arise outside of agriculture, for example, in areas such as flood prevention, landslide prevention, and other disaster prevention measures.

[0007] The present disclosure has been devised to solve the above-mentioned problems. That is, a main purpose of the present disclosure is to propose a technology that can provide precipitation information even in places where a rain gauge is not installed.

[0008] In order to achieve the above-mentioned object, in one aspect, the precipitation estimation device of the present disclosure comprises: an acquisition unit that acquires, as soil moisture content information, information on soil moisture content, which is the amount of moisture contained in the soil at the estimation target location, measured using a soil moisture sensor installed at the estimation target location for estimating precipitation; an estimation unit that estimates the precipitation at the estimation target location using information on changes in soil moisture content over time based on the soil moisture content information; and an output unit that outputs information on the estimated precipitation.

[0009] In addition, one aspect of the precipitation estimation method of the present disclosure is to use a computer to acquire, as soil moisture information, information on soil moisture content, which is the amount of moisture contained in the soil at the location of the estimation target, measured using a soil moisture sensor installed at the location of the estimation target for which precipitation is to be estimated; estimate the amount of precipitation at the location of the estimation target using information on changes in soil moisture content over time based on the soil moisture content information; and output information on the estimated precipitation.

[0010] Furthermore, in one aspect, the program storage medium of the present disclosure stores a computer program that causes a computer to execute the following processes: a process of acquiring, as soil moisture information, information on soil moisture content, which is the amount of moisture contained in the soil at the location of the estimation target, measured using a soil moisture sensor installed at the location of the estimation target for estimating precipitation; a process of estimating the amount of precipitation at the location of the estimation target using information on changes in soil moisture content over time based on the soil moisture content information; and a process of outputting information on the estimated amount of precipitation.

[0011] According to the present disclosure, precipitation information can be provided even in places where no rain gauge is installed.

[0012] FIG. 1 is a diagram illustrating an example of the configuration of an embodiment of a precipitation estimation device according to the present disclosure. FIG. 2 is a diagram illustrating an example of changes in soil moisture content over time in a farm field. FIG. 3 is a model diagram illustrating an example of moisture flow in soil. FIG. 4 is a diagram illustrating a crop coefficient. FIG. 5 is a diagram illustrating an example of a display of estimated precipitation information. FIG. 6 is a diagram illustrating an example of a display displaying information on precipitation and soil moisture content. FIG. 7 is a flowchart illustrating an example of a precipitation estimation process performed by a precipitation estimation device according to the present disclosure. FIG. 8 is a diagram illustrating an example of a configuration of another embodiment of a precipitation estimation device according to the present disclosure. FIG. 9 is a flowchart illustrating another example of a precipitation estimation process performed by a precipitation estimation device according to the present disclosure.

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0014] First Embodiment The precipitation estimation device of the first embodiment is a computer device that has the function of estimating precipitation at a target location without using a rain gauge. Precipitation refers to the amount of water that falls on the ground as rain or snow, and here, precipitation due to rain is mainly assumed. The target location is a location for which precipitation is to be estimated, and in this case, it is a location where the soil is exposed and rain, snow, etc. falls directly on the soil (in other words, an open field). In the first embodiment, the target location is an outdoor field (i.e., indoor fields such as the inside of a greenhouse are not included).

[0015] The precipitation estimation device of the first embodiment estimates precipitation using information on changes in soil moisture content over time at a location to be estimated. Soil moisture content is the amount of water contained in soil. There are several ways to express soil moisture content, such as water content ratio, weight moisture content, and volumetric moisture content, and the calculation method (definition) differs depending on the type. Here, the type of soil moisture content expression is not limited as long as the expression used in the processing is consistent. In the following description, the type of expression for soil moisture content will be referred to simply as soil moisture content, without distinguishing between different expressions.

[0016] A soil moisture sensor may be installed in a farm field to adjust (control) the amount of water supplied to the farm field by irrigation. A soil moisture sensor is a sensor that can measure the amount of soil moisture. In the first embodiment, the soil moisture information used to estimate the amount of precipitation is acquired using the soil moisture sensor. By using an existing soil moisture sensor in this way, there is an advantage that it is not necessary to install a new rain gauge in the farm field.

[0017] That is, as shown in FIG. 1 , the precipitation estimation device 1 of the first embodiment is connected to a plurality of information sources 3, such as a storage device that stores soil moisture information. One of the information sources 3 is an information source that can provide the precipitation estimation device 1 with information about soil moisture content at a location to be estimated, such as a storage device that stores soil moisture information. The soil moisture information stored in the storage device is information acquired by a soil moisture sensor 9 installed at the location to be estimated, as described above. The storage device serving as the information source 3 stores, for example, soil moisture measurement values ​​measured by the soil moisture sensor 9 at predetermined time intervals. The measurement values ​​are associated with measurement time information indicating the time of measurement and field identification information that identifies the field that is the location to be estimated. Note that, depending on the size of the location to be estimated, multiple soil moisture sensors 9 may be installed. In such cases, the soil moisture measurement values ​​stored in the storage device serving as the information source 3 are associated with sensor identification information that identifies the soil moisture sensor 9 that performed the measurement. Furthermore, if multiple soil moisture sensors 9 are installed at the location to be estimated, the average value of the soil moisture measurements by these soil moisture sensors 9 may be stored in the storage device serving as the information source 3 as the soil moisture content at the location to be estimated.

[0018] In addition, instead of connecting a storage device such as that described above to the precipitation estimation device 1 as an information source for providing information on the soil moisture content at the location to be estimated, a soil moisture sensor 9 installed at the location to be estimated may be connected to the precipitation estimation device 1 as an information source 3.

[0019] In the first embodiment, the precipitation estimation device 1 is further connected to an information source 3 that provides meteorological information for a location to be estimated. Examples of meteorological information provided to the precipitation estimation device 1 by the information source 3 include temperature (e.g., hourly average temperature), solar radiation (e.g., hourly average solar radiation), relative humidity (e.g., hourly average relative humidity), wind speed (e.g., hourly average wind speed), and the accumulated temperature and accumulated solar radiation for a predetermined period, all of which are related to the evaporation (discharge) of water from soil and crop leaf surfaces. Note that meteorological items such as solar radiation, humidity, and wind speed are less localized than precipitation, and it is expected that sufficient accuracy will be maintained even if the information is acquired from a weather sensor (such as a pyranometer, hygrometer, or anemometer) installed at a location 10 kilometers or more away.

[0020] In the first embodiment, as described above, the precipitation estimation device 1 is connected to a plurality of types of information sources 3. Here, the same reference numerals are assigned to information sources that provide information to the precipitation estimation device 1, even if the information sources are of different types.

[0021] In the first embodiment, the precipitation estimation device 1 is further connected to an input device 7 as shown in Fig. 1 and, if necessary, is further connected to a database 4. The input device 7 is a device through which an operator of the precipitation estimation device 1 (hereinafter also referred to as a device operator) inputs information to the precipitation estimation device 1, and is configured with a keyboard, a mouse, etc. The database 4 is a storage device, and, if necessary, stores information acquired from the information source 3, information input by the input device 7, data calculated by the precipitation estimation device 1, etc.

[0022] The precipitation estimation device 1 in the first embodiment is a server device, and as shown in FIG. 1 , this precipitation estimation device 1 is further connected to a terminal device 5. The terminal device 5 is a computer device operated by a user who is a farm-related person (such as a farm manager or a crop producer). The terminal device 5 has a communication function and a display control function that controls the display device 8 to display information. The terminal device 5 is not limited to any information device equipped with a communication function and a display control function, and specific examples include a personal computer (PC), a tablet, and a smartphone. Note that if the terminal device 5 is a smartphone or a tablet, the display device 8 is integrated with the terminal device 5, but if the terminal device 5 is a PC, the display device 8 may be external. The connection between the terminal device 5 and the precipitation estimation device 1 is executed by an application program (app) that provides the terminal device 5 with a function to link with the precipitation estimation device 1. Alternatively, the connection between the terminal device 5 and the precipitation estimation device 1 may be executed by a browser (software for browsing information on the Internet). Whether the connection between the terminal device 5 and the precipitation estimation device 1 is performed via an app or a browser is set appropriately by a system designer or the like, and is not limited here. Furthermore, although one terminal device 5 is connected to the precipitation estimation device 1 in the example of Fig. 1, the precipitation estimation device 1 can be connected to multiple terminal devices 5 of different users.

[0023] The precipitation estimation device 1 has a configuration as shown in Fig. 1. That is, the precipitation estimation device 1 includes a calculation device 10 and a storage device 20. The storage device 20 has a storage medium for storing data and a computer program (hereinafter also referred to as a program) 22. There are multiple types of storage devices, and a computer device is provided with multiple types of storage devices depending on the application. Here, the types and number of storage devices provided in the precipitation estimation device 1 are not limited, and a description thereof will be omitted.

[0024] The arithmetic device 10 is configured with a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The arithmetic device 10 can have various functions based on a program 22 stored in a storage device 20 by reading and executing the program 22. In the first embodiment, the arithmetic device 10 has an acquisition unit 11, an estimation unit 12, and an output unit 13 as functional units related to the process of estimating precipitation.

[0025] The acquisition unit 11 acquires soil moisture information at the estimation target location from the information source 3 as described above, and also acquires meteorological information at the estimation target location from the information source 3. In other words, the soil moisture information acquired by the acquisition unit 11 is information measured using the soil moisture sensor 9 installed at the estimation target location. An example of the timing at which the acquisition unit 11 acquires the soil moisture information from the information source 3 is when an acquisition command is input to the precipitation estimation device 1 by the device operator operating the input device 7. The acquisition command is a command requesting the acquisition of soil moisture information. When the acquisition unit 11 acquires the soil moisture information in response to the acquisition command from the device operator, for example, information on a target acquisition period for acquiring the soil moisture information (in other words, a period for which precipitation is desired to be estimated) is also input via the input device 7. The acquisition unit 11 acquires soil moisture information measured during the input target acquisition period from the information source 3. Furthermore, when multiple locations (fields) for estimation are set, information indicating the field for which soil moisture content information is to be acquired is input to the precipitation estimation device 1 by the input device 7. In this case, the acquisition unit 11 acquires soil moisture content information of the field according to the input field information.

[0026] Another example of the timing at which the acquisition unit 11 acquires soil moisture content information from the information source 3 is at predetermined time intervals. In this case, for example, measurements taken by the soil moisture sensor 9 are constantly updated in the information source 3, which is a storage device that stores the soil moisture content information. The acquisition unit 11 acquires unacquired soil moisture content information from the information source 3 at predetermined time intervals. In such a case, if multiple estimation target locations (fields) are set, the acquisition unit 11 acquires unacquired soil moisture content information for all estimation target locations at predetermined time intervals.

[0027] As described above, the soil moisture content information acquired by the acquisition unit 11 from the information source 3 is stored in one or both of the storage device 20 and the database 4. The stored soil moisture content information is appropriately associated with information useful for reading and managing information, such as information on the measurement time and field identification information of the corresponding field.

[0028] The timing at which the acquisition unit 11 acquires the weather information for the estimation target location from the information source 3 may be, for example, at predetermined time intervals. In this case, for example, the acquisition unit 11 acquires weather information for the estimation target location for the period between the time intervals of the acquisition timings. Furthermore, if multiple estimation target locations (fields) are set, the acquisition unit 11 acquires weather information for all estimation target locations, for example, at each acquisition timing.

[0029] As described above, the weather information acquired by the acquisition unit 11 from the information source 3 is stored in one or both of the storage device 20 and the database 4. The stored weather information is appropriately associated with information useful for reading and managing the information, such as information on the corresponding time period and field identification information of the field.

[0030] The acquisition unit 11 may also be configured to acquire, for example, information about the location of the estimation target using the terminal device 5. That is, while it is conceivable that the device operator inputs information such as the type of crop cultivated in the location (field) of the estimation target (field) and basic information about the field into the precipitation estimation device 1 using the input device 7, the acquisition unit 11 may acquire such information from field personnel using the terminal device 5. For example, the acquisition unit 11 may display an information registration screen on the display device 8 of the terminal device 5 to prompt the field personnel to input the information desired to be acquired from the field personnel, and may prompt the field personnel to input information into the information registration screen using a notification method such as a message. The acquisition unit 11 then acquires the information entered into the information registration screen from the terminal device 5. The information acquired in this manner is, for example, associated with the field identification information and stored in the storage device 20 or the database 4.

[0031] The estimation unit 12 estimates the amount of precipitation at the estimation target location using the soil moisture information and meteorological information acquired by the acquisition unit 11. That is, in the first embodiment, the estimation unit 12 estimates the amount of precipitation using information on the change in soil moisture over time due to the infiltration of rainwater that falls on the ground surface into the soil, as shown in FIG. 2 . Here, a model of moisture flow in soil, as shown in FIG. 3 , is used to estimate the amount of precipitation. This model focuses on the Lth layer (hereinafter also referred to as layer L) from the surface side of multiple layers into which the soil is virtually divided. In FIG. 3 , sm(t, L) represents the soil moisture content of layer L at time t. Furthermore, flow(t, L) represents the amount of moisture flowing from the layer one layer above layer L (hereinafter also referred to as layer (L-1)) to layer L at time t. Furthermore, flow(t, L+1) represents the amount of moisture flowing from layer L to the layer one layer below it (hereinafter also referred to as layer (L+1)) at time t. Furthermore, F represents the amount of water flowing from the L layer to layers other than the (L+1) layer at time t. In the first embodiment, since the location of the estimation target is a farm field, it is assumed that crops are grown in the location of the estimation target. Crops absorb water from the soil. Therefore, in a farm field, F is considered to be approximately equivalent to the amount of water absorbed mainly by the crops (in other words, the amount of water absorbed by the roots of the crops (hereinafter also referred to as root water absorption)). Therefore, in the following description, the amount of water flowing from the L layer to layers other than the (L+1) layer at time t, F, will also be represented as the amount of water absorbed by the roots in the L layer due to crop evapotranspiration (root water absorption) ETc(t, L).

[0032] Here, ETc(t, L) will be explained. ETc(t, L) can be calculated by the following formula (1).

[0033]

[0034] In formula (1), ET0 represents the reference evapotranspiration. The reference evapotranspiration is the evapotranspiration of a reference crop grown under conditions where water is sufficiently supplied. The reference crop represents a crop in a reference growth state, such as a crop with a plant height of 8 to 15 centimeters during growth. The reference evapotranspiration ET0 can be calculated as the evapotranspiration of the reference crop under given weather conditions. Information on weather conditions for calculating the reference evapotranspiration ET0 is acquired by the acquisition unit 11.

[0035] Additionally, Kc in Equation (1) represents the crop coefficient. The crop coefficient varies depending on the type of crop and its growth stage. Figure 4 shows a graph illustrating an example of the relationship between the growth stage of a crop and the crop coefficient. In the example in Figure 4, the crop growth stages are divided into four stages: early, growing, intermediate, and terminal. The change in the crop coefficient according to the growth stage of the crop varies depending on the type of crop. Possible methods for estimating the growth stage of a crop include estimating the number of days elapsed since sowing or planting, estimating based on changes in the shape of the crop, such as the number of expanded leaves, number of branches, flowering, and fruit set, and estimating by quantifying the growth status of the crop using satellites or drones.

[0036] In addition, Root(t, L) in formula (1) represents the proportion of crop roots present in the Lth layer. Root(t, L) may be a value that varies in each layer over time, or a constant value that is independent of time may be set for each layer. Root(t, L) satisfies the following formula:

[0037]

[0038] Therefore, by using the reference evapotranspiration ET0 and crop coefficient Kc obtained as described above and equation (1), it is possible to calculate the amount of water absorption by roots in the L layer ETc(t, L). Note that the amount of water absorption by roots in the L layer ETc(t, L) is calculated using ET0 calculated using the meteorological information acquired by the acquisition unit 11 as described above and the crop coefficient Kc, which changes depending on the growth stage of the crop, and therefore it can also be said to be information on the amount of water absorption by the crop adjusted using the meteorological information and the growth stage of the crop.

[0039] In the model shown in Figure 3, if the soil moisture content of the L layer at time (t+1) is expressed as sm(t+1, L), the soil moisture content sm(t+1, L) can be expressed by the following equation (3).

[0040]

[0041] The amount of precipitation at the target location (field) can be estimated by considering the L layer as the top layer in the model shown in Figure 3. In other words, the amount of precipitation Rain(t) at the target location (field) at time t can be considered to be approximately equivalent to the amount of water (flow(t, L) + Drain(t)), which is the sum of the amount of water that permeates into the top layer (L layer), flow(t, L), and the amount of water that flows away without permeating into the top layer (L layer), Drain(t).

[0042] The amount of water flow(t, L) that permeates into the outermost layer (L layer) can be expressed as in Equation (4) by modifying Equation (3).

[0043]

[0044] In equation (4), (sm(t+1,L) - sm(t,L)) represents the change in soil moisture content over time in the topmost layer (layer L). In the first embodiment, information on the change in soil moisture content over time can be obtained using the soil moisture sensor 9. Furthermore, ETc(t,L) can be calculated as described above using equation (1) taking into account the type of crop grown in the location (field) to be estimated and meteorological information.

[0045] Furthermore, flow(t, L+1) can be expressed by the following equation (5).

[0046]

[0047] In equation (5), FC(L+1) represents the soil (field) water capacity in the (L+1) layer. Soil (field) water capacity is the maximum amount of water that soil can hold against gravity drainage. SLDR(L+1) represents the soil drainage rate in the (L+1) layer. th(L+1) represents the thickness of the (L+1) layer. FC(L+1) and SLDR(L+1) in equation (5) are affected by soil properties such as texture. Therefore, FC(L+1) and SLDR(L+1) for the target location (field) can be calculated through experiments or simulations that take into account soil properties such as texture. Furthermore, sm(t, L+1) is the soil moisture content, which can be determined using the soil moisture sensor 9. Therefore, flow(t, L+1) in equation (5) can be calculated.

[0048] The amount of water that flows away without soaking into the top layer (L layer) of precipitation, Drain(t), can be estimated through experiments and simulations that take into account the properties of the top layer (L layer), such as the soil texture.

[0049] Therefore, as described above, it is possible to calculate the amount of water that has soaked into the top layer (L layer) due to rainfall at time t, flow(t, L), and the amount of water that has flowed away without soaking into the top layer (L layer), Drain(t). The amount of precipitation, Rain(t), can be calculated by adding these amounts of water, flow(t, L) and Drain(t).

[0050] As described above, the estimation unit 12 calculates the precipitation Rain(t) using information on the change in soil moisture content over time at the location of the estimation target, information on the type of crop being cultivated, weather information for the location of the estimation target, and formulas (1), (4), and (5). Formulas (1), (4), and (5) include constants and coefficients obtained through experiments and simulations. The time interval between time t and time (t+1) may be set appropriately, for example, to one hour.

[0051] In the above example, the process of estimating precipitation has been described assuming that the soil has a layered structure. The process of estimating precipitation can be performed in a similar manner even when the soil does not have a layered structure. For example, the process of calculating the amount of water transfer (or water balance) on the surface of a specific area of ​​the soil can also be performed in a similar manner. The process of calculating the amount of precipitation is not limited to the above example.

[0052] The estimation unit 12 associates the calculated precipitation amount with time information indicating the time (e.g., date and time) corresponding to the precipitation amount, and stores the information as precipitation amount history information in the storage device 20. The precipitation amount history information is associated with field identification information that identifies the location (field) for which the precipitation amount was estimated.

[0053] The output unit 13 outputs the precipitation information estimated by the estimation unit 12. One of the destinations to which the output unit 13 outputs the precipitation information is, for example, the terminal device 5. The output unit 13 outputs the precipitation information, for example, when it receives a precipitation information output request from the terminal device 5. The precipitation information output request is a command requesting precipitation information, and, for example, the request is associated with field identification information representing the field for which precipitation information is requested and period information representing the period for which the information is to be provided. Upon receiving such a precipitation information output request, the output unit 13 reads, from the storage device 20, precipitation information for the field represented by the field identification information associated with the precipitation information output request, which is precipitation information for the period specified by the period information. The output unit 13 then returns the read precipitation information to the terminal device 5.

[0054] In the terminal device 5 that has received the precipitation information from the precipitation estimation device 1, the received precipitation information is displayed on the screen of the display device 8 using a pre-set display template, for example, by display control of the terminal device 5. Fig. 5 shows an example of the display of precipitation information on the display device 8.

[0055] The precipitation estimation device 1 may output soil moisture information used to estimate the precipitation amount (information on the soil moisture amount measured by the soil moisture sensor 9) in addition to the precipitation amount information to the terminal device 5. In this case, for example, the terminal device 5 may display the soil moisture amount information on the display device 8 in addition to the precipitation amount information, as shown in Fig. 6 .

[0056] A display device (not shown) may be connected to the precipitation estimation device 1. In this case, when the output unit 13 detects that a precipitation information output request has been input to the precipitation estimation device 1 by an operator operating the input device 7, the output unit 13 displays (outputs) precipitation information on the display device connected to the precipitation estimation device 1, as shown in Figs. 5 and 6 .

[0057] The precipitation estimation device 1 of the first embodiment is configured as described above. Next, an example of the operation related to precipitation estimation in the precipitation estimation device 1 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of the operation related to precipitation estimation in the precipitation estimation device 1.

[0058] For example, the acquisition unit 11 in the precipitation estimation device 1 acquires predetermined information to be acquired (such as soil moisture information, weather information, and crop types) from the information source 3 or the terminal device 5 (step 101). The timing of acquiring the information is set for each type of information to be acquired.

[0059] Thereafter, the estimation unit 12 estimates the amount of precipitation at the location of the estimation target using the information acquired by the acquisition unit 11 (step 102). For example, the amount of precipitation is estimated by the above-mentioned method using the change in soil moisture over time.

[0060] The estimation unit 12 also registers the information on the estimated amount of precipitation in the storage device 20 or the database 4 (step 103).

[0061] Thereafter, it is determined whether a precipitation information output request (hereinafter also referred to as an information output request for short) has been received from the terminal device 5 (step 104). If an information output request has not been received, the operations from step 101 onwards are repeated. If an information output request has been received, the output unit 13 reads out precipitation information corresponding to the field identification information and period information associated with the information output request from the storage device 20 or the database 4. The output unit 13 then returns (outputs) the read information to the terminal device 5 (step 105). In the terminal device 5 that has received the precipitation information, the precipitation information is displayed on the screen by the display device 8. After outputting the precipitation information to the terminal device 5, the precipitation estimation device 1 repeats the information from step 101 onwards.

[0062] As described above, the precipitation estimation device 1 of the first embodiment has a function of estimating the amount of precipitation at a location (field) of interest using the change over time in soil moisture output from the soil moisture sensor 9 already installed at the location. As a result, the precipitation estimation device 1 can estimate the amount of precipitation at the location of interest and provide information about the estimated amount of precipitation to, for example, people involved in the field, even if a rain gauge is not installed at the location of interest or a new rain gauge is not installed.

[0063] Furthermore, the change in soil moisture content over time in the field, which is the location of the estimation target, is affected not only by rainfall but also by water absorption by the crops grown in the field. For this reason, the estimation unit 12 of the precipitation estimation device 1 calculates the precipitation amount taking into account the influence of water absorption by the crops (i.e., the amount of water absorption ETc by the roots of the crops). As a result, even if the location of the estimation target is a field, the precipitation estimation device 1 can estimate the precipitation amount without reducing the estimation accuracy.

[0064] Furthermore, the amount of water absorption ETc of the roots of crops grown in the field, which is the location of the estimation target, varies depending on weather conditions (temperature, humidity, wind speed, etc.). Taking this into consideration, the precipitation estimation device 1 of the first embodiment estimates precipitation using the amount of water absorption ETc of the roots of crops that is determined by taking into account weather conditions as described above. This allows the precipitation estimation device 1 to improve the accuracy of estimating precipitation in the field.

[0065] Other Embodiments The present disclosure is not limited to the first embodiment and may employ various other embodiments. For example, if the precipitation estimation device 1 is further connected to a computer device 30, as shown by the dotted line in FIG. 1 , the output unit 13 may also output precipitation information to the computer device 30. The computer device 30 calculates the amount of water (irrigation supply water amount) to be supplied to a field using irrigation equipment using precipitation information. When providing precipitation information to such a computer device 30, the precipitation estimation device 1 can provide the computer device 30 with useful information that can improve the accuracy of calculating the irrigation supply water amount. That is, there are cases where the estimation target location (field) is far from the nearest rain gauge, for example, the distance to the nearest rain gauge is 10 kilometers or more. In such cases, it is possible that the precipitation measured by the rain gauge differs from the actual precipitation at the estimation target location. For this reason, if the irrigation water supply amount is calculated using information on the most recent precipitation measured by a rain gauge, the field may be irrigated with an irrigation water supply amount that deviates from the optimal irrigation water supply amount corresponding to the actual precipitation. In such a situation, even if a rain gauge is not installed in the field, the precipitation estimation device 1 provides information on the precipitation amount in the field, allowing the computer device 30 to calculate the optimal irrigation water supply amount corresponding to the precipitation. In other words, the precipitation estimation device 1 can provide the computer device 30 with useful information that can improve the accuracy of calculating the irrigation water supply amount.

[0066] Furthermore, although the first embodiment has been described using a farm field as an example of the location to be estimated, the location to be estimated is not limited to a farm field. For example, a mountain slope on which a soil moisture sensor is installed for disaster prevention purposes may be used as the location to be estimated, and precipitation may be estimated in the same manner as in the first embodiment. Furthermore, the location to be estimated may be a location where no plants are planted. When no plants are planted in the location to be estimated, the amount of water F flowing from the L layer to a layer other than the (L+1) layer is used in the above-mentioned formulas (3) and (4) instead of the amount of water absorption by the roots ETc(t, L). The amount of water F is determined by experiments and simulations that take into account the properties of the soil at the location to be estimated, such as the texture of the soil.

[0067] Furthermore, if the location to be estimated is divided into multiple areas and at least one soil moisture sensor is installed in each area, the estimation unit 12 may estimate the amount of precipitation for each area of ​​the location to be estimated using the change in soil moisture over time in each area. For example, if the location to be estimated is vast and the amount of precipitation varies depending on the location, it is possible to determine the amount of irrigation water supply for each area using information on the change in precipitation over time for each area, enabling more precise control of the amount of irrigation water supply.

[0068] Furthermore, as another embodiment of the precipitation estimation device according to the present disclosure, for example, a configuration as shown in FIG. 8 may be adopted. The precipitation estimation device 50 shown in FIG. 8 is, for example, a computer device, and includes an acquisition unit 51, an estimation unit 52, and an output unit 53 as functional units realized by executing a pre-set computer program. The acquisition unit 51 acquires information on the soil moisture content of the soil at the estimation target location as soil moisture content information using a soil moisture sensor installed at the estimation target location. The estimation target location refers to the location for which precipitation is to be estimated. The soil moisture content is the amount of moisture contained in the soil.

[0069] The estimation unit 52 estimates the amount of precipitation at the location of the estimation target using information on the change in soil moisture over time based on the soil moisture information. The output unit 53 outputs the estimated amount of precipitation. The acquisition unit 11, the estimation unit 12, and the output unit 13 described in the first embodiment are specific examples of the acquisition unit 51, the estimation unit 52, and the output unit 53.

[0070] The precipitation estimation device 50 in Fig. 8 is configured as described above. An example of the operation of the precipitation estimation device 50 relating to precipitation estimation will be described with reference to Fig. 9. Fig. 9 is a flowchart illustrating an example of the operation of the precipitation estimation device 50 relating to precipitation estimation.

[0071] For example, the estimation unit 52 acquires soil moisture information at the location of interest using a soil moisture sensor installed at the location of interest (step 201).The estimation unit 52 then estimates the amount of precipitation at the location of interest using information on changes in soil moisture over time based on the soil moisture information (step 202).Then, the output unit 53 outputs the estimated amount of precipitation information (step 203).

[0072] The precipitation estimation device 50 estimates the amount of precipitation at a location using information on changes in soil moisture over time measured using a soil moisture sensor. Therefore, the precipitation estimation device 50 can provide information on the amount of precipitation at a location where a rain gauge is not installed, without installing a new rain gauge.

[0073] The precipitation estimation device 50 may further determine the amount of water to be supplied to the field by irrigation (i.e., the irrigation supply water amount) from the determined precipitation. In this case, the precipitation estimation device 50 may determine the irrigation supply water amount, for example, by applying a relational expression that holds between precipitation and irrigation supply water amount to the estimated precipitation. Alternatively, the precipitation estimation device 50 may create a model that represents the relationship that holds between precipitation and irrigation supply water amount by machine learning, and determine the irrigation supply water amount by applying the created model to the estimated precipitation.

[0074] The precipitation estimation device 50 may further supply the determined irrigation water supply amount to an apparatus that irrigates a field (hereinafter referred to as an "irrigation device"). The irrigation device receives the irrigation water supply amount and irrigates the field in accordance with the irrigation water supply amount. In this case, the precipitation estimation device 50 functions as a control device that controls the irrigation device.

[0075] Alternatively, the precipitation estimation device 50 may transmit the amount of precipitation to a device managing the field (hereinafter referred to as the "management device"). In this case, the management device receives the amount of precipitation, calculates the amount of irrigation water supply based on the received amount of precipitation, and stores the calculated amount of irrigation water supply in a storage device. The management device then transmits the amount of irrigation water supply for each area of ​​the field to irrigation devices installed in that area. The irrigation devices receive the irrigation water supply amount and irrigate the field in accordance with the irrigation water supply amount. Even in this case, the precipitation estimation device 50 can also be said to function as a control device that controls the irrigation device. In this case, the processing can also be said to be processing in which the control device controls the irrigation device to perform an operation determined based on the amount of precipitation.

[0076] Alternatively, the precipitation estimation device 50 may transmit the amount of precipitation to a management device that manages disaster prevention facilities such as dams. In this case, the management device may receive the amount of precipitation and determine the amount of water to be released from the dam based on the received amount of precipitation. The management device may then control the opening degree of the floodgates according to the determined amount of water to be released. In this case, the precipitation estimation device 50 can also be said to function as a control device that controls the operation of the dam.

[0077] Alternatively, the precipitation estimation device 50 may transmit the amount of precipitation to a system for preventing urban disasters. In this case, the system may receive the amount of precipitation and, for example, determine the amount of water to send to an underground waterway based on the received amount of precipitation. The management device may then control an adjustment device that adjusts the amount of water flowing into the underground waterway according to the determined amount of water. In this case, the precipitation estimation device 50 can also be said to function as a control device that controls the operation of the dormitory equipment.

[0078] Some or all of the above embodiments may be described as, but are not limited to, the following supplementary notes. [Supplementary Note 1] A precipitation estimation device comprising: an acquisition unit that acquires, as soil moisture information, information on soil moisture content, which is the amount of moisture contained in the soil at a location where precipitation is to be estimated, measured using a soil moisture sensor installed at the location; an estimation unit that estimates precipitation at the location where precipitation is to be estimated using information on changes in soil moisture content over time based on the soil moisture content information; and an output unit that outputs information on the estimated precipitation. [Supplementary Note 2] The precipitation estimation device according to Supplementary Note 1, wherein the location where precipitation is to be estimated is a farm field, and the estimation unit estimates precipitation at the location where precipitation is to be estimated using information on crop water absorption from the soil by crops grown at the location where precipitation is to be estimated. [Supplementary Note 3] The precipitation estimation device according to Supplementary Note 1, wherein the output unit outputs the soil moisture content information used to estimate precipitation in association with precipitation information. [Supplementary Note 4] The precipitation estimation device according to Supplementary Note 2, wherein the acquisition unit further acquires meteorological information for the estimation target location, and the estimation unit estimates precipitation at the estimation target location using information on the crop water absorption adjusted using the acquired meteorological information. [Supplementary Note 5] The precipitation estimation device according to Supplementary Note 2, wherein the output unit outputs to a device that calculates an amount of water to be supplied to the estimation target location using irrigation equipment using precipitation information. [Supplementary Note 6] A precipitation estimation method, comprising: acquiring, by a computer, soil moisture information, information on soil moisture content, which is the amount of moisture contained in the soil at the estimation target location, measured using a soil moisture sensor installed at the estimation target location where precipitation is to be estimated; estimating precipitation at the estimation target location using information on changes in soil moisture content over time based on the soil moisture information; and outputting information on the estimated precipitation. [Supplementary Note 7] The precipitation estimation method according to Supplementary Note 6, wherein the estimation target location is a farm field, and the computer estimates the amount of precipitation at the estimation target location by further using information on crop water absorption from the soil by crops grown at the estimation target location. [Supplementary Note 8] The precipitation estimation method according to Supplementary Note 6, wherein the computer also outputs soil moisture information used to estimate the amount of precipitation in association with the information on the amount of precipitation.[Supplementary Note 9] The precipitation estimation method according to Supplementary Note 7, further comprising: acquiring, by a computer, meteorological information for the location of the estimation target; and estimating precipitation at the location of the estimation target using information on the crop water absorption adjusted using the acquired meteorological information. [Supplementary Note 10] The precipitation estimation method according to Supplementary Note 7, further comprising: outputting, by a computer, to a device that calculates, by using the precipitation information, an amount of water to be supplied to the location of the estimation target using irrigation equipment. [Supplementary Note 11] A computer program that causes a computer to execute the steps of: acquiring, as soil moisture information, information on soil moisture content, which is the amount of moisture contained in the soil at the location of the estimation target, measured using a soil moisture sensor installed at the location of the estimation target where precipitation is to be estimated; estimating precipitation at the location of the estimation target using information on changes in soil moisture content over time based on the soil moisture information; and outputting information on the estimated precipitation. [Supplementary Note 12] The computer program according to Supplementary Note 11, wherein the location of the estimation target is a farm field, and the process of estimating precipitation is a process of estimating precipitation at the location of the estimation target by also using information on crop water absorption, which is water absorbed from the soil by crops grown at the location of the estimation target. [Supplementary Note 13] The computer program according to Supplementary Note 11, wherein the process of outputting precipitation information is a process of outputting soil moisture information used for estimating precipitation in association with the precipitation information. [Supplementary Note 14] The computer program according to Supplementary Note 12, further including a computer program causing a computer to execute the processes of: further acquiring meteorological information for the location of the estimation target; and estimating precipitation at the location of the estimation target by using the information on crop water absorption adjusted using the acquired meteorological information. [Supplementary Note 15] The computer program according to Supplementary Note 12, further including a computer program causing a computer to execute the process of outputting to a device that calculates the amount of water to be supplied to the location of the estimation target using irrigation equipment using precipitation information.

[0079] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0080] This application claims priority based on Japanese Patent Application No. 2023-172463, filed October 4, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0081] 1, 50 Precipitation estimation device 9 Soil moisture sensor 11, 51 Acquisition unit 12, 52 Estimation unit 13, 53 Output unit

Claims

1. A precipitation estimation device comprising: an acquisition means for acquiring, as soil moisture information, information on soil moisture content, which is the amount of moisture contained in the soil at a location to be estimated, measured using a soil moisture sensor installed at the location to be estimated; an estimation means for estimating the amount of precipitation at the location to be estimated using information on changes in soil moisture content over time based on the soil moisture information; and an output means for outputting information on the estimated amount of precipitation.

2. The precipitation estimation device as described in claim 1, wherein the location to be estimated is a farm field, and the estimation means estimates the amount of precipitation at the location to be estimated by also using information on the amount of water absorbed from the soil by crops grown in the location to be estimated.

3. The precipitation estimation device according to claim 1, wherein the output means outputs soil moisture information used in estimating the amount of precipitation in association with information on the amount of precipitation.

4. The precipitation estimation device as described in claim 2, wherein the acquisition means further acquires meteorological information for the location of the estimation target, and the estimation means estimates the precipitation for the location of the estimation target using information on the crop water absorption adjusted using the acquired meteorological information.

5. The precipitation estimation device according to claim 2, wherein the output means outputs to a device that uses precipitation information to calculate the amount of water to be supplied to the location of the estimation target for irrigation.

6. A precipitation estimation method, comprising: acquiring, by a computer, soil moisture information, which is the amount of moisture contained in the soil at a location to be estimated, measured using a soil moisture sensor installed at the location to be estimated; estimating the amount of precipitation at the location to be estimated using information on changes in soil moisture over time based on the soil moisture information; and outputting information on the estimated amount of precipitation.

7. A program storage medium storing a computer program for causing a computer to execute the following processes: a process of acquiring, as soil moisture information, information on soil moisture content, which is the amount of moisture contained in the soil at a location to be estimated, measured using a soil moisture sensor installed at the location to be estimated for precipitation; a process of estimating the amount of precipitation at the location to be estimated using information on changes in soil moisture content over time based on the soil moisture information; and a process of outputting information on the estimated amount of precipitation.

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