JP7123224B1 - Groundwater level estimation system - Google Patents

Abstract

An object of the present invention is to provide a groundwater level estimation system capable of estimating a groundwater level with high accuracy while performing simple and maintenance-free measurement. A groundwater level estimation system 100 includes a plurality of moisture measuring units 11a, 11b, and 11c installed at different depths to measure moisture in soil, and a plurality of moisture measuring units 11a, 11b, and 11c. An estimated value calculation unit 53 for estimating the groundwater level based on the measurement result and the depth difference between the plurality of moisture measurement units 11a, 11b, and 11c. [Selection drawing] Fig. 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a groundwater level estimation system for estimating temporal fluctuations in groundwater level, which can be one of indicators for determining the degree of risk of slope failure, for example.

As a system for monitoring a slope, for example, a technique using various measurement and calculation methods related to slope stability analysis is known (see Patent Document 1). Also, there is a known system that employs a pore water pressure gauge to monitor landslides on slopes (see Patent Document 2).

However, although Patent Documents 1 and 2 disclose a system for monitoring a slope, it is not always easy to monitor or observe with good maintainability over the long term. When a pore water pressure gauge is used to measure the water level, for example, as in Patent Document 2, periodic maintenance is required for the pore water pressure gauge installed on site to measure various data necessary for monitoring the slope. It is difficult to build a system that is easy to manage.

Retable 2016/027390 JP 2019-101744 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a groundwater level estimating system capable of estimating the groundwater level with high accuracy while performing simple and maintenance-free measurement.

The groundwater level estimation system for achieving the above purpose comprises a plurality of moisture measuring units installed at different depths to measure the moisture in the soil, and the measurement results of the multiple moisture measuring units and the moisture measuring units. and an estimated value calculator for estimating the groundwater level based on the difference in depth between the two.

In the above-described groundwater level estimation system, a plurality of moisture measuring units are installed at different depths, and the moisture content in the soil is measured at each depth position of each moisture measuring unit. By estimating the groundwater level based on the measurement result of the measuring unit and the difference in the depth position (measurement position), it is easy to measure the moisture in the soil like a soil moisture meter, and the maintenance burden is low. It is possible to estimate the groundwater level with high accuracy even if a moisture measuring part that is light or does not get wet is adopted as each moisture measuring part.

In a specific aspect of the present invention, the depth difference between the plurality of moisture measuring units is determined according to the measurable range of each moisture measuring unit. In this case, by combining a plurality of moisture measuring units, appropriate measurement can be performed for the entire depth range necessary for water level estimation.

In another aspect of the present invention, the estimated value calculation unit performs the saturation determination in order from the moisture measurement unit installed at the deepest portion among the plurality of moisture measurement units, and the moisture measurement unit determined to be unsaturated is the deepest. Estimate the pressure head for In this case, appropriate water level estimation can be performed by estimating according to the procedure.

According to still another aspect of the present invention, the plurality of moisture measuring units are configured by providing moisture detectors at the ends of a plurality of bar-shaped members having mutually different lengths. In this case, the water level can be estimated from the detection result of the moisture detector provided at the end of each rod-like member.

According to still another aspect of the present invention, the plurality of moisture measuring units are integrally configured by providing a plurality of moisture detecting units at predetermined intervals in one rod-shaped member. In this case, the water level can be estimated from the detection results of a plurality of moisture detectors provided on one rod-like member.

In still another aspect of the present invention, the estimated value calculator estimates the water level change based on changes in the measured values of the plurality of moisture measuring units. In this case, by capturing the change in the measured value, it is possible to estimate the chronological change in the water level.

According to still another aspect of the present invention, the present invention comprises a transmission section that transmits measurement results obtained by the plurality of moisture measurement sections, and a reception section that is arranged apart from the plurality of moisture measurement sections and receives the measurement results from the transmission section. , the estimated value calculator aggregates the measurement results received by the receiver to estimate the groundwater level. In this case, the groundwater level is estimated based on the aggregated measurement results at a location distant from the plurality of moisture measuring units.

In still another aspect of the present invention, the water content measurement unit measures the volumetric water content in the soil from the dielectric constant. In this case, maintenance is simple, and reliable measurement is achieved.

In still another aspect of the present invention, the moisture measuring section is configured by a soil moisture meter. In this case, using a plurality of soil moisture meters enables the measurements necessary for estimating the water level.

BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram for demonstrating the outline|summary of the groundwater level estimation system which concerns on 1st Embodiment. It is a block diagram for demonstrating one structural example of a groundwater level estimation system. (A) to (C) are conceptual diagrams showing changes in the groundwater level. (A) and (B) are conceptual diagrams for explaining the estimation of the groundwater level. It is a figure which shows about the method of water level observation as a comparative example. It is a flowchart for demonstrating an example about the operation|movement in a field terminal. FIG. 10 is a flowchart for explaining an example of observation data reception processing in a data center; FIG. 4 is a flowchart for explaining an example of arithmetic processing in a data center; 4 is a flowchart for explaining an example of determination processing and display (output) processing in a data center; (A) and (B) are conceptual diagrams showing an example of occurrence of an abnormality in a field terminal. It is a conceptual diagram for demonstrating the outline|summary of the groundwater level estimation system which concerns on 2nd Embodiment. It is a conceptual diagram for demonstrating the outline|summary of the groundwater level estimation system which concerns on 3rd Embodiment. (A) to (C) are conceptual diagrams for explaining an outline of another example of the groundwater level estimation system. (A) to (D) are conceptual diagrams for explaining the outline of still another example of the groundwater level estimation system.

[First Embodiment]
An example of the groundwater level estimation system according to the first embodiment will be described below with reference to FIG. 1 and the like. As shown in FIG. 1 and the like, a groundwater level estimation system 100 according to the present embodiment includes a field terminal 10 installed in a field SI that is an object to observe the groundwater level, and a data center that receives information from the field terminal 10. 50. In the illustrated example, a plurality of on-site terminals 10 are installed in the on-site SI such as a slope where the groundwater level is to be estimated, and observation data OD as a result of measurement (observation) at each on-site terminal 10 is transmitted from the on-site SI. It transmits (transmits) wirelessly to the data center 50 installed at a remote location. In the data center 50, the observation data OD from each on-site terminal 10 is aggregated to estimate the groundwater level at the on-site SI. Furthermore, the data center 50 acquires information such as observation data OD from each field terminal 10 and other information such as meteorological data from the outside to determine the situation of the field SI and determine the degree of risk. It is good also as what is possible to judge.

Hereinafter, one configuration example of the groundwater level estimation system 100 will be described with reference to the block diagram shown as FIG. For the sake of simplification, the illustration shows that one field terminal 10 is communicating with the data center 50 .

In the groundwater level estimation system 100, the field terminal 10 includes a sensor unit 11 composed of a plurality of (three in the illustrated example) moisture measurement units 11a, 11b, and 11c, a storage unit 12, a communication unit 13, It has a battery 14 and a main control section 15 connected to each section, and each section is housed in a housing SC. In the sensor unit 11, a plurality of moisture measuring units 11a, 11b, and 11c are partially protruding from the housing SC toward the ground GN and buried in the underground UN. In this example, the sensor unit 11 is composed of three moisture measuring units 11a, 11b, and 11c with different installation positions (depths). The number of moisture measuring units constituting the sensor unit 11 at one installation location may be changed as appropriate according to the capacity.

The on-site terminal 10 is a device installed at the on-site SI and for sending the status of the installation location to the data center 50, as described above. In the illustrated example, the on-site terminal 10 has a housing SC containing each part installed on the ground GN of the on-site SI, and the moisture measuring units 11a, 11b, and 11c are installed at different depths. A plurality of moisture measurement units 11a, 11b, and 11c measure the moisture in the underground UN at different depths in a state of being vertically embedded with respect to the ground GN from the ground GN toward the underground (under the ground) UN. . In addition, the main control unit 15 sends various data regarding the results measured by the moisture measurement units 11a, 11b, and 11c to the data center 50 as information indicating the situation at the installation location.

Details of each part of the field terminal 10 will be described below. First, of the field terminal 10, the sensor unit 11, that is, each of the moisture measuring units 11a, 11b, and 11c, has rod-shaped members BA with different lengths, and electrodes ER as moisture detectors MD at the ends thereof. It is set up and configured. Each moisture measurement part 11a, 11b, 11c can be configured by, for example, a soil moisture meter. In the illustrated example, the moisture measuring unit 11a is installed on the shallowest side, that is, the side closest to the ground GN, the moisture measuring unit 11c is installed on the deepest side, that is, the side far from the ground GN, and the moisture measuring unit 11b is installed between them. is set up. Each of the moisture measurement units 11a, 11b, and 11c energizes the electrode ER, which is the tip portion (the deepest portion), to measure the dielectric constant of the soil, and calculates the moisture content near the electrode ER from the measured dielectric constant. be done. Here, it is assumed that volumetric water content is acquired as the observation data OD as the water content in each of the water measuring units 11a, 11b, and 11c. The groundwater level estimation system 100 estimates the water level (upper end position of the groundwater area R1 indicated by hatching with oblique lines) based on this observation data OD.

When a soil moisture meter is used as the moisture measuring unit 11a, etc., it is possible to estimate based on the measurement results for a range of about 50 cm in the depth direction, although it is also affected by soil quality and the like. Therefore, for example, the distances (differences in depth) DDa, DDb, and DDc between the moisture measuring units 11a, 11b, and 11c are set to about 50 cm each, and the moisture measuring units 11a, 11b, and 11c are responsible for this. As for the measurement range, the three moisture measurement units 11a, 11b, and 11c as a whole can have an observable range DDx of about 150 cm in the depth direction. In the illustrated example, in the underground (soil) UN, the range of the observable range DDx, that is, the respective moisture measurement units 11a, 11b, and 11c, so that the soil layer LY2 existing as a region above the bedrock LY1 can be measured. placement is determined.

The storage unit 12 is configured by, for example, a storage device or the like. The storage unit 12 is connected to the sensor unit 11, that is, the three moisture measuring units 11a, 11b, and 11c, and records observation data OD about soil moisture, that is, volumetric water content, detected by the moisture measuring units 11a, 11b, and 11c. . In this case, the storage unit 12 cooperates with the sensor unit 11 and functions as a logger that records the observation data OD.

The communication unit 13 is a device for communicating with the data center 50 , and transmits and receives various data including observation data OD according to commands from the main control unit 15 . That is, the communication unit 13 functions as a transmission unit that transmits observation data OD as measurement results by the plurality of moisture measurement units 11a, 11b, and 11c.

The battery 14 is a power source for supplying electric power to each section that constitutes the field terminal 10 and for maintaining the power drive in each section.

The main control unit 15 is composed of, for example, a CPU, an electronic circuit, or a combination of these and a storage device. Performs overall control of the entire operation. Here, in particular, timing control of moisture detection operations in the three moisture measuring units 11a, 11b, and 11c and transmission (output) of the recorded observation data OD to the data center 50 via the communication unit 13 are performed. . The main control unit 15 also performs various management operations such as checking the remaining amount of the battery 14 and reporting the check result to the data center 50 .

Details of the data center 50 in the groundwater level estimation system 100 will be described below. The data center 50 includes a communication section 51 , a data server 52 , an estimated value calculation section 53 and an output device 54 .

As described above, the data center 50 is provided apart from the site SI, receives information from the plurality of site terminals 10 installed at various locations of the site SI in the communication unit 51, and transmits the received information to the data server. 52 summarizes the data, and based on this, the estimated value calculation unit 53 estimates the groundwater level at the site SI. The estimated result is displayed on an output device 54 configured by a display unit such as a display panel, for example.

The communication unit 51 can communicate with the communication unit 13 of the field terminal 10 so as to function as a device for communicating with the field terminals 10 installed in various places. That is, the communication unit 51 is arranged apart from the plurality of moisture measurement units 11a, 11b, and 11c, and functions as a reception unit that receives measurement results (observation data OD) from the communication unit 13, which is a transmission unit.

The data server 52 manages various data including observation data OD received from the field terminal 10 via the communication unit 51 . Although detailed illustration and description are omitted, the data server 52 manages various information from the outside such as weather forecast information in the field SI in addition to the information from the field terminal 10, and the data center 50 Based on this information, it is possible to comprehensively judge various risks such as the possibility of a landslide occurring at the site SI.

The estimated value calculation unit 53 is composed of, for example, a CPU, an electronic circuit, etc., and estimates the groundwater level at the site SI based on the observation data OD from the site terminal 10 . More specifically, based on the results of measurement by the plurality (three) of moisture measurement units 11a, 11b, and 11c that constitute each field terminal 10 and the depth difference between the plurality of moisture measurement units 11a, 11b, and 11c, It is a computing device for estimating the groundwater level in the field SI. Note that the output device 54 outputs and displays, for example, the result of estimation of the groundwater level by the estimated value calculation unit 53 and the like.

3A to 3C, which are conceptual diagrams of the on-site SI in which the on-site terminal 10 is installed, will be described below with reference to changes in the groundwater level and the moisture measurement unit 11a, which constitutes the sensor unit 11. Moisture measurement by 11b and 11c will be described.

3A to 3C conceptually show how the water level rises (or falls) in the underground UN. In the illustrated example, the underground UN has a structure in which a soil layer LY2 that easily absorbs moisture is formed on a hard bedrock LY1. The groundwater contained in the underground UN is formed when water such as spring water permeates the soil layer LY2, and is indicated by the hatched region R1 in the figure, as described above. That is, the region R1 indicating groundwater is a region above the bedrock LY1 and in the soil layer LY2, and the upper end of the region R1 (the end closest to the ground surface) indicates the groundwater level WL1 in the soil layer LY2. ing. The groundwater level estimation system 100 is for estimating the position of this groundwater level WL1. Moreover, as described above, the plurality of moisture measuring units 11a, 11b, and 11c are provided to grasp the condition of the region R1 according to the condition of the underground UN.

Here, as shown in FIG. 3A, first, let h be the soil layer thickness, which is the distance in the depth direction from the ground surface position GN1 to the bedrock LY1 (the boundary BD between the bedrock LY1 and the soil layer LY2), Let Za, Zb, and Zc be installation depths, which are the distances from the position GN1 to the electrodes ER of the respective moisture measuring units 11a, 11b, and 11c. In this case, Za<Zb<Zc<h. Here, for these, for example, a survey on the underground UN is conducted in advance, and the value of the soil layer thickness h and the soil quality are known. Therefore, it is assumed that the installation depths Za, Zb, and Zc are determined by a suitable design.

Further, as described above, the measurement range of the moisture measurement unit 11a is assumed to be the range indicated by the distance DDa. Similarly, the measurement range of the moisture measurement unit 11b is the range indicated by the distance DDb, and the measurement range of the moisture measurement unit 11c is the range indicated by the distance DDc. Here, as an easy-to-understand example, it is assumed that each of the above values satisfies the following formulas.
Za + DDa = Zb
Zb + DDb = Zc
Zc + DDc = h
That is, the measurement ranges of the respective moisture measurement units 11a, 11b, and 11c are not superimposed and are continuous, and the range connecting the distance DDa to the distance DDc is the observable range DDx of the field terminal 10. It is assumed that there is In other words, the field terminal 10 defines the observable range DDx as the range from the boundary BD between the bedrock LY1 and the soil layer LY2 to the installation depth Za where the moisture measurement unit 11a is installed.

Here, the estimation of the water level based on the volumetric water content measured (measured) by each of the moisture measuring units 11a, 11b, and 11c is performed based on the volumetric water content having an unsaturated value. When the positions of the electrodes ER of the moisture measuring units 11a, 11b, and 11c become lower than the groundwater level WL1, that is, when the electrodes ER are included in the region R1, the volumetric water content is saturated. That is, the volumetric water content becomes the maximum value. On the other hand, if the position of the electrode ER is higher than the groundwater level WL1, the volumetric water content will be unsaturated. That is, the volumetric water content becomes a value lower than the maximum value. At this time, the closer the groundwater level WL1 is, the greater the value of the volumetric water content. For example, in FIGS. 3A to 3C, the electrode ER of the moisture measurement unit 11c shows a value at which the volumetric water content becomes unsaturated only in FIG. In FIG. 3(C), the value at which the volumetric water content is saturated is shown. This is because, in the case shown in FIG. 3A, the groundwater level WL1 is in the range indicated by the distance DDc, and in this case, the position of the groundwater level WL1 can be estimated based on the volumetric water content measured by the moisture measuring unit 11c. will be done. In other words, the measurement result of the moisture measurement unit 11c is adopted from the transmitted observation data OD. On the other hand, in the cases shown in FIGS. 3B and 3C, the measurement results of the other moisture measurement units 11a and 11b are adopted.

Hereinafter, the moisture measurement in the states shown in FIGS. 3(A) to 3(C) will be described in more detail.

First, in the case of the state shown in FIG. 3A, that is, when the groundwater level WL1 is the electrode ER (moisture detection unit MD) is not reached. In this case, for example, the soil near the electrode ER of the moisture measuring unit 11c closest to the bedrock LY1 is considered to contain a certain amount of moisture. It is assumed that the other moisture measurement units 11a and 11b, which are considered to be absent, are detected with different numerical values. Therefore, in this case, more accurate estimation is possible by estimating the position of the groundwater level WL1 based on the volumetric water content measured by the water measuring unit 11c.

On the other hand, in the state shown in FIG. 3B, that is, the groundwater level WL1 is above the position of the electrode ER of the moisture measuring unit 11c, and the electrode ER of the moisture measuring unit 11c is included in the region R1. However, the case where the water does not reach the electrodes ER of the two moisture measurement units 11a and 11b will be considered. In this case, it is considered that a value indicating that the saturated volumetric water content has been reached is detected at the electrode ER of the moisture measuring unit 11c. That is, the volumetric water content shows the maximum value. On the other hand, it is assumed that the electrodes ER of the two moisture measurement units 11a and 11b detect different numerical values (values not reaching the saturated volumetric moisture content). Moreover, it is assumed that there is also a difference in the detected values between the moisture measuring unit 11a and the moisture measuring unit 11b. Therefore, in this case, more accurate estimation is possible by estimating the position of the groundwater level WL1 based on the volumetric water content measured by the water measuring unit 11b.

Finally, when the state shown in FIG. Consider a case where the electrode ER of 11c is included in the region R1, but does not reach the electrode ER of the moisture measuring section 11a. In this case, it is considered that the electrodes ER of the two moisture measurement units 11b and 11c detect a value indicating that the saturated volumetric moisture content has been reached. On the other hand, it is assumed that the electrode ER of the moisture measurement unit 11a detects a different numerical value (a value that does not reach the saturated volumetric water content). Therefore, in this case, more accurate estimation is possible by estimating the position of the groundwater level WL1 based on the volumetric water content measured by the water measuring unit 11a.

As described with reference to FIGS. 3(A) to 3(C), here, when there are a plurality of observation points determined to be unsaturated, the lowest observation point among them (from the position GN1 closest to the ground surface) The observation value at the distant position) is adopted.

In this embodiment, as described above, the sensor unit 11 is composed of a plurality of moisture measuring units 11a, 11b, and 11c whose positions are different with respect to depth, and the groundwater level WL1 is determined based on the difference in the detection results among these. is assumed to be estimated. As a result, in the groundwater level estimation system 100 of the present embodiment, each of the moisture measurement units 11a, 11b, and 11c is, for example, a soil moisture meter, which is simple and requires little or no maintenance burden when measuring moisture in the soil. , it is possible to estimate the groundwater level with high accuracy.

A specific example of a method of calculating the estimated value of the groundwater level with the above configuration will be described below with reference to the conceptual diagram shown as FIG. 4(A) is a diagram corresponding to FIG. 3(C), and FIG. 4(B) is a diagram corresponding to FIG. 3(B). In the drawing, a region R1 occupied by groundwater in the soil layer LY2 is defined as a gravity water region WR1, and a region above the region R1 (gravity water region WR1) is defined as a pore water region WR2.

Here, first, it is assumed that the already-described soil layer thickness h and installation depths Za, Zb, and Zc are already known. may also be shown. Further, let ψ (≦0; negative value) be the pressure head based on the position of the installation depth Z. The pressure head ψ is obtained from the volumetric water content, which is the observed value in each of the water measuring units 11a, 11b, and 11c. In addition, hereinafter, the volumetric water content is set to θ. therefore,
ψ=ψ(θ)
and A specific example of the relational expression between the pressure head ψ and the volumetric water content θ (calculation of the pressure head ψ based on the volumetric water content θ) will be described later.

Further, the height from the bedrock LY1 indicates the groundwater level WL1, and as shown in the figure, this height is d. That is, the height d indicating the groundwater level WL1 is the value to be obtained in the groundwater level estimation system 100. As shown in the figure, the above parameters are used to
d=h−Z+ψ (1)
is expressed as For example, in the case shown in FIG. 4(A), as shown with reference to FIG. 3(C), the value used as the volumetric water content is measured by the water content measurement unit 11a indicated by the asterisk in FIG. 4(A). We adopt the observations that That is, among those whose volumetric water content θ is unsaturated, the one located at the lowest observation point is adopted. That is, in the illustrated example, not only the water content measuring section 11c but also the water content measuring section 11b are saturated. Therefore, in the above case, the reference position for calculating the pressure head ψ is set to the installation depth Z = Za, and the above equation (1) is
d=h−Za+ψ(θ) (2)
However, the volumetric water content θ is the value of the volumetric water content measured by the water measuring unit 11a.

Similarly, in the case shown in FIG. 4(B), the above formula (1) is
d=h−Zb+ψ(θ) (3)
However, the volumetric water content θ is the value of the volumetric water content measured by the water measuring unit 11b. Although illustration etc. are omitted, for the case corresponding to FIG. 3(A),
d=h−Zc+ψ(θ) (4)
However, the volumetric water content θ is the value of the volumetric water content measured by the water measuring unit 11c.

ここで、体積含水率θを含む各パラメータ等は、以下の通りであり、これらは、土壌の状態等に応じて、適宜定められる。

Here, as for the method of calculating the pressure head ψ, it is conceivable to use various known methods. Specifically, for example, the following example is conceivable.

Here, each parameter including the volumetric water content θ is as follows, and these are appropriately determined according to the condition of the soil and the like.

The above formula (5) is obtained by modifying the following van Genuchten model, which is a known formula.

となる。 Regarding the applicable range of the volumetric water content θ,

becomes.

As described above, the height d, that is, the position of the groundwater level WL1 can be estimated.

It is also conceivable to predict the stability of the soil at the field terminal 10 based on the height d (the position of the groundwater level WL1) estimated as described above.

ここで、上式のうち、ｍは、地下水位比である、つまり、土層厚ｈと高さｄ（地下水位ＷＬ１の位置）との比率であり、以下に示すものとなる。

なお、上式（８）におけるｍ以外のパラメータは、下記の通りである。

As one known method of analyzing (determining) soil stability, based on the relationship between the gravitational water region WR1 and the pore water region WR2, the ratio of the shear stress τ _d and the shear resistance force τ _r , which utilizes the slope stability Fs expressed by the following equation. It is conceivable to use this analysis method.

Here, in the above formula, m is the groundwater level ratio, that is, the ratio between the soil layer thickness h and the height d (the position of the groundwater level WL1), and is given below.

Parameters other than m in the above equation (8) are as follows.

Regarding the above equation (8), it is generally considered that if the slope stability Fs is 1 or more, it is stable, and if it is less than 1, it is unstable. That is, by using the estimation result based on the measurement at the field terminal 10, the groundwater level ratio m shown in the above equation (9) can be calculated whether the slope stability Fs is 1 or more or less than 1. It is also possible to apply this calculation result as one of the indices indicating the danger of soil in the field terminal 10 .

A groundwater level estimation system of a comparative example will be described below with reference to FIG. FIG. 5 is a conceptual diagram showing, as a comparative example, an observation method for estimating the water level by a technique different from that of the present embodiment.

As a method for detecting the state of the soil for estimating the water level, various methods are conceivable in addition to the example described in the above embodiment. It is contemplated to utilize a pore water pressure gauge WP, as one shown. That is, it is conceivable to estimate the groundwater level by measuring the pore water pressure in the soil with the pore water pressure gauge WP. However, when using the pore water pressure gauge WP, periodic maintenance such as replenishment of enclosed deaerated water and bubble removal is required. In particular, when observing signs of the occurrence of natural disasters, it is necessary to carry out observation over a long period of time.

On the other hand, as another method, for example, like another example similarly shown in FIG. It is conceivable to use MM. When using a soil moisture meter, as in the case described in the above embodiment, measurement can be continued if, for example, electric power is secured for supplying electricity to the moisture detection unit MD (electrode ER). Compared to the total WP, it does not require regular maintenance and can easily perform long-term measurement. However, as mentioned above, the detectable range of the soil moisture meter MM is about 50 cm in the depth direction, so there is a possibility that the range necessary for observing changes in the groundwater level cannot be satisfied. be.

On the other hand, in the present embodiment, by installing a plurality of moisture measuring units (for example, three moisture measuring units 11a, 11b, and 11c) at different depths, maintenance such as a soil moisture meter can be performed. It is easy to use, but even if it uses something with a limited detection range, it is configured to accurately capture the state of changes in the groundwater level.

In addition, regarding the estimation of the groundwater level in the groundwater level estimation system 100 of the above aspect, the above-described arithmetic processing is performed on the observation data OD in the estimated value calculation unit 53 constituting the data center 50. . That is, the estimated value calculation unit 53 performs saturation determination on the moisture measurement unit 11b and the moisture measurement unit 11a in order from the moisture measurement unit 11c installed in the deepest part among the plurality of moisture measurement units 11a, 11b, and 11c, The pressure head ψ is estimated for the deepest one among the water content measuring portions determined to be unsaturated. Furthermore, the estimated value calculation unit 53 also predicts water level changes based on changes in the measured values of the plurality of moisture measurement units 11a, 11b, and 11c.

An example of the operation of each part of the groundwater level estimation system 100 will be described below with reference to flowcharts shown in FIGS.

First, with reference to FIG. 6, an example of operation processing in the field terminal 10, that is, collection of observation data OD will be described.

First, the main control unit 15 of the field terminal 10 first confirms whether or not it is a predetermined time (step S101) in order to collect the observation data OD every unit time (every 10 minutes in the illustrated example). (step S101: No), it waits until a predetermined time (step S102). At a predetermined time (step S101: Yes), the main control unit 15 causes all three moisture measurement units 11a, 11b, and 11c constituting the sensor unit 11 to perform measurement, and the storage unit 12 records the data. Let Along with this, these measurement results are collected as observation data OD (volumetric water content θ) (step S103).

Next, the main control unit 15 transmits the observation data OD collected in step S103 to the data center 50 (data server 52) via the communication unit 13 (step S104).

Regarding the transmission in step S104, if there is no abnormality in the transmission result (step S105: Yes), the main control unit 15 repeats the operation from step S101. If there is an abnormality in the transmission result (step S105: No), the operation is stopped and terminated. Typically, a connection/transmission failure or the like is conceivable.

Next, an example of operation processing mainly in the data server 52 in the data center 50 will be described with reference to FIG.

First, the data server 52 of the data center 50 confirms whether or not the latest observation data OD (volumetric water content θ) has been received from each field terminal 10 via the communication unit 51 (whether or not data has been received) (step S201 ), if there is no confirmation (step S201: No), it waits for a predetermined time (step S202). After a predetermined period of time has elapsed, step S201 is confirmed again, and this is repeated. In step S201, when confirmation is made (step S201: Yes), the data server 52 stores the received observation data OD in a predetermined storage area in the data server 52 (step S203). The received observation data OD is transmitted (output) to the estimated value calculator 53 (step S204).

Regarding the transmission in step S204, if there is no abnormality in the transmission result (step S205: Yes), the data server 52 repeats the operation from step S201. If there is an abnormality in the transmission result (step S205: No), the operation is stopped and terminated. Typically, a connection/transmission failure or the like is conceivable.

Next, with reference to FIG. 8, an example of operation processing in the estimated value calculation section 53, which is mainly a calculation device, in the data center 50 will be described. That is, an example of arithmetic processing for estimating the groundwater level (calculating the height d) based on the above-described volumetric water content θ will be described. Also, here, the analysis of the slope stability Fs described above is also performed.

First, the estimated value calculation unit 53 of the data center 50 confirms whether the latest observation data OD (volumetric water content θ) has been received from the data server 52 (step S301). Otherwise (step S301: No), wait for a predetermined time (step S302), and when the predetermined time has passed, confirm step S301 again and repeat this. In step S301, when confirmation is made (step S301: Yes), the estimated value calculation unit 53 performs saturation/unsaturation at each depth as described with reference to FIGS. is determined (step S303).

Based on the determination result of step S303, the gravity water region WR1 is determined, and at the same time, it is confirmed whether or not the saturation determination is made at all depths (step S304).

In step S304, if the determination is not saturated at all depths (step S304: No), the estimated value calculation unit 53 calculates the observed value at the deepest one, that is, the lowest observation point among the unsaturated ones. A pressure head ψ is calculated from (volumetric water content θ) (step S305).

Further, the estimated value calculator 53 calculates the value of the height d as an estimated value of the groundwater level based on the pressure head ψ calculated in step S304, and calculates the groundwater level ratio m (step S306).

The estimated value calculator 53 analyzes the slope stability Fs based on the groundwater level ratio m calculated in step S306 (step S307).

On the other hand, in step S304, if the saturation determination is made at all depths (step S304: Yes), the estimated value calculation unit 53 determines that the gravitational water region WR1 is the most It is determined that the water level is higher than the observation range of the moisture measuring unit 11a installed at a shallow position. In this case, the estimated value calculation unit 53 treats the value of the groundwater level ratio m as m=1, that is, assuming that the upper end of the gravity water region WR1 is at a height corresponding to the ground surface (step S308), the slope stability Fs in this state is analyzed (step S307).

After step S307, the estimated value calculation unit 53 transmits the value of the slope stability Fs as the analysis result calculated in step S307 to the data server 52, and the value is stored in a predetermined storage area in the data server 52. It is saved (stored) (step S309).

If there is no abnormality in the transmission result to the data server 52 in step S309 (step S310: Yes), the estimated value calculation unit 53 repeats the operation from step S301. If there is an abnormality in the transmission result (step S310: No), the operation is stopped and terminated. Typically, a connection/transmission failure or the like is conceivable.

Finally, with reference to FIG. 9, an example of determination of slope stability Fs and output display of various data will be described.

First, in the data server 52 of the data center 50, the stored observation data OD and the slope stability Fs are read (step S401), and for example, in the estimated value calculation unit 53, etc., the soil based on the slope stability Fs In other words, it is confirmed whether the value of slope stability Fs is 1 or more or less than 1 (step S402).

In step S402, when the value of the slope stability Fs is 1 or more, that is, when it is determined that the soil is stable (step S402: No), the data server 52 causes the output device 54 to issue an alarm, Observation data OD and slope stability Fs are output (step S403).

On the other hand, in step S402, when the value of the slope stability Fs is less than 1, that is, when it is determined that the soil is unstable (step S402: Yes), the data server 52 causes the output device 54 to issue an alarm , observation data OD and slope stability Fs are output to call attention (step S404).

As described above, if the slope stability Fs value is less than 1, that is, if the situation where the soil is determined to be unstable continues, for example, as shown in FIG. As shown in FIG. 10(B), the field terminal 10, which had been normally installed with the terminal 11 buried in the ground, was exposed to the ground due to the occurrence of an abnormality such as a landslide. It is also assumed that it will be in a situation where it will come. In the state shown in FIG. 10B, it is assumed that the value (permittivity value) detected by the sensor unit 11 indicates a numerical value that is impossible in the ground. Therefore, when such a numerical value is transmitted to the data center 50, it is not a device failure of the field terminal 10 seen in connection failure etc. as exemplified in step S105 of FIG. It can be taken as what is happening.

As described above, the groundwater level estimation system 100 according to the present embodiment includes a plurality of moisture measuring units 11a, 11b, and 11c installed at different depths to measure the moisture in the soil, and a plurality of moisture measuring units. An estimated value calculation unit 53 for estimating the groundwater level based on the measurement results of the moisture measurement units 11a, 11b, and 11c and the difference in depth between the plurality of moisture measurement units 11a, 11b, and 11c. In the groundwater level estimation system 100, the water content in the soil is measured at each depth position of each of the water content measurement units 11a, 11b, and 11c installed at different depths. By estimating the groundwater level based on the measurement results of the units 11a, 11b, and 11c and the difference in their depth positions (measurement positions), it is possible to easily measure the moisture content in the soil like a soil moisture meter. It is possible to estimate the groundwater level with high accuracy even if a moisture measuring unit that requires little or no maintenance is adopted as each moisture measuring unit.

[Second embodiment]
An example of the groundwater level estimation system 100 according to the second embodiment will be described below with reference to FIG. 11 . In this embodiment, the configuration of the sensor unit 11 is different from that of the groundwater level estimation system 100 described as an example of the first embodiment. Note that the overall configuration of the groundwater level estimation system 100 other than the above viewpoints is the same as in the case of the first embodiment, so detailed description of each component denoted by the same reference numeral in the overall configuration will be omitted. .

FIG. 11 is a conceptual diagram for explaining the outline of the groundwater level estimation system 100 according to the present embodiment, and is a diagram corresponding to the field terminal 10 in FIG. As shown in the figure, in the field terminal 10 constituting the groundwater level estimation system 100 according to the present embodiment, the sensor unit 11, that is, the plurality of moisture measuring units 11a, 11b, and 11c detect a plurality of moisture levels in one rod-shaped member BAx. Parts MD (electrodes ER) are provided at predetermined intervals and integrated. That is, in the case of the present embodiment, the water level can be estimated from the detection results (observation data OD) of a plurality of moisture detectors MD (electrodes ER) provided on one rod-shaped member BAx.

Also in the present embodiment, by estimating the groundwater level based on the measurement results of the moisture measurement units 11a, 11b, and 11c constituting the sensor unit 11 and the difference in their depth positions (measurement positions), It is possible to estimate the groundwater level with high accuracy while performing simple and maintenance-free measurement. In particular, in the present embodiment, the installation burden of the field terminal 10 can be reduced, for example, by integrating the sensor unit 11 .

[Third embodiment]
An example of the groundwater level estimation system 100 according to the third embodiment will be described below with reference to FIG. 12 . The present embodiment differs from the groundwater level estimation system 100 and the like described as an example of the first embodiment in that one field terminal 10 is provided with a plurality of sensor units 11 . Note that the overall configuration of the groundwater level estimation system 100 other than the above viewpoints is the same as in the case of the first embodiment, so detailed description of each component denoted by the same reference numeral in the overall configuration will be omitted. .

FIG. 12 is a conceptual diagram for explaining the outline of the groundwater level estimation system 100 according to this embodiment, and is a diagram corresponding to the field terminal 10 in FIG. As illustrated, in the field terminal 10 that constitutes the groundwater level estimation system 100 according to the present embodiment, a plurality of sensor units 11 (three in the illustrated example) are provided. Moisture measurement units 11 a , 11 b , and 11 c each perform measurement, and the detection results (observation data OD) of each of the plurality of sensor units 11 are collectively recorded in storage unit 12 and transmitted by communication unit 13 . .

Also in the present embodiment, the groundwater level is estimated based on the measurement results of the moisture measurement units 11a, 11b, and 11c constituting each sensor unit 11 and the difference in their depth positions (measurement positions). , it is possible to estimate the groundwater level with high accuracy while making the measurement simple and maintenance-free. In particular, in this embodiment, a plurality of sensor units 11 can be collectively installed and managed.

〔others〕
The present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the scope of the invention.

First, the matters described in each of the above-described embodiments are examples, and not limited to these, various modifications can be considered.

Furthermore, the direction in which the moisture measuring section is embedded can also be changed in various ways. In each of the above-described embodiments, the depth direction of the moisture measurement units 11a, 11b, and 11c (the direction that determines the difference in depth) is the normal direction when the ground GN is viewed as a plane, but the present invention is not limited to this. A mode as shown in FIG. 13 is conceivable. Specifically, as shown in FIG. 13A, when the site SI has a shape with an inclined surface (slope), the direction along the direction of gravity G is shown by the dashed line LL. With respect to this direction, it is conceivable to adopt a mode in which moisture measurement is performed at measurement target points PP that are different depth positions at predetermined intervals. Moreover, in this case, as shown in FIG. The sensor unit 11 of the field terminal 10 may be extended in a direction perpendicular to the direction of gravity G (horizontal direction).

Further, as shown in FIGS. 14A and 14B, a large number (N pieces; for example, N is an integer of 4 or more) of the sensor units 11 may be grouped together to form a collective configuration. Furthermore, various aspects can be considered for how the sensor unit 11 spreads in the underground UN. For example, as shown in FIG. As shown, it is also conceivable that the sensor section 11 extends horizontally at different depths.

In addition, in the above, the saturation of the volumetric water content θ may be defined in consideration of the sensing accuracy of the sensor section 11 . For example, if θe is the observation error of the sensor unit 11, and θ≧θs−θe, then it is considered as saturation.

Further, in the above description, all of the volumetric water content θ measured by the moisture measuring units 11a, 11b, and 11c of the field terminal 10 is transmitted as the observation data OD. As long as the data can be transmitted to the center 50, the purpose can be achieved. For example, the on-site terminal 10 may check whether the volumetric water content θ is saturated or unsaturated, and may transmit only the volumetric water content θ at the bottom observation point, which is the observed value to be adopted, as the observation data OD. . Furthermore, from the viewpoint of one of the indicators to measure the degree of danger, if the lowest observation point where the saturation becomes unsaturated is at a depth that is clearly not dangerous, only the signal indicating that there is no danger will be used as the observation data OD at the site. A configuration in which the terminal 10 transmits to the data center 50 is also conceivable. In other words, a configuration may be adopted in which part of the processing of the data center 50 is carried out on the field terminal 10 side.

Further, for example, the data center 50 is not limited to being configured with physical servers or the like, and may be configured as a cloud, for example.

DESCRIPTION OF SYMBOLS 10... Field terminal, 11... Sensor part, 11a, 11b, 11c... Moisture measuring part, 12... Storage part, 13... Communication part, 14... Battery, 15... Main control part, 50... Data center, 51... Communication part, 52 Data server 53 Estimated value calculator 54 Output device 100 Underground water level estimation system BA, BAx Rod-shaped member BD Boundary DDa, DDb, DDc Distance DDx Observable range ER ... electrode, Fs ... slope stability, G ... direction of gravity, GN ... ground, GN1 ... position, LL ... dashed line, LY1 ... bedrock, LY2 ... soil layer, MD ... moisture detector, MM ... soil moisture meter, OD ... observation data, PP... measurement target point, R1... area, SC... housing, SI... site, UN... underground, WL1... ground water level, WP... pore water pressure gauge, WR1... gravity water area, WR2... pore water area, Z, Za, Zb, Zc... Installation depth, h... Soil layer thickness, m... Groundwater level ratio, θ... Volumetric water content, τ _d ... Shear stress, τ _r ... Shear resistance, ψ... Pressure head, θe... Observation error , θs: saturated volumetric water content, θr: residual volumetric water content, ψ1: air entry pressure parameter, n: pore diameter parameter

Claims (9)

a plurality of moisture measuring units installed at different depths to measure moisture in the soil;
an estimated value calculation unit for estimating the groundwater level based on the measurement results of the plurality of moisture measurement units and the difference in depth between the plurality of moisture measurement units;
The groundwater level estimation system, wherein the estimated value calculation unit estimates the pressure head of the deepest moisture measurement unit determined as unsaturated in the saturation determination based on the measurements in the plurality of moisture measurement units. 2. The groundwater level estimation system according to claim 1, wherein the difference in depth between said plurality of moisture measuring units is determined according to the measurable range of each moisture measuring unit. The groundwater level estimation system according to any one of claims 1 and 2, wherein the estimated value calculation unit performs saturation determination in order from the moisture measurement unit installed at the deepest portion among the plurality of moisture measurement units. The groundwater level estimation system according to any one of claims 1 to 3, wherein the plurality of moisture measuring units are configured by providing moisture detecting units at the ends of a plurality of bar-shaped members having mutually different lengths. The groundwater level according to any one of claims 1 to 3, wherein the plurality of moisture measuring units are integrated with a plurality of moisture detecting units provided at predetermined intervals in one rod-shaped member. estimation system. 6. The groundwater level estimation system according to any one of claims 1 to 5, wherein said estimated value calculation unit estimates changes in water level based on changes in measured values of said plurality of moisture measurement units. a transmission unit that transmits measurement results obtained by the plurality of moisture measurement units;
a receiving unit arranged apart from the plurality of moisture measuring units and configured to receive measurement results from the transmitting unit;
The groundwater level estimation system according to any one of claims 1 to 6, wherein the estimated value calculation unit aggregates the measurement results received by the reception unit to estimate the groundwater level. The groundwater level estimation system according to any one of claims 1 to 7, wherein the moisture measurement unit measures the volumetric moisture content in the soil from a dielectric constant. The groundwater level estimating system according to any one of claims 1 to 8, wherein said moisture measuring unit is composed of a soil moisture meter.

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