Highest groundwater level measuring device and method for measuring the highest groundwater level

Abstract

To provide a method and device for more easily measuring the highest groundwater level in soil, by specializing in measuring the highest groundwater level in soil. [Solution] A maximum groundwater level measuring device used by being installed inside a cylindrical member, comprising a long support rod and a plurality of recording members provided at intervals along the longitudinal direction of the support rod, the recording members having a reversible change in appearance between a wet state and a dry state.

Description

Technical Field

[0001] The present invention relates to a maximum groundwater level measuring device and a method for measuring the maximum groundwater level.

Background Art

[0002] One of the judgment materials for determining whether a field is suitable for cultivating crops is the groundwater level of the field. This is because when the groundwater level rises to the rhizosphere soil, it has an adverse effect on the growth and quality of crops.

[0003] For example, in citrus fruits, by preventing rainwater from infiltrating into the soil with a multi-sheet and drying the rhizosphere soil, and by applying drying stress to the citrus fruits, fruits with high sugar content and good quality can be obtained. However, it has been reported that in fields where the groundwater level is high due to reasons such as a shallow impervious layer, the soil does not dry even when a multi-sheet is laid, and the sugar content becomes low.

[0004] Therefore, grasping the groundwater level of the field, particularly the maximum groundwater level, is important for determining suitable land for crops and performing good water management.

[0005] As a general method for grasping the temporal change of the water level including the groundwater level, there is an observation method using a water level gauge and a data logger. Although this method can accurately obtain the temporal change of the water level including the maximum water level, since the use of expensive equipment is essential, there is a problem that it is difficult for agricultural producers, agricultural extension officers, etc. to use it at the site of agricultural production, etc.

[0006] On the other hand, methods for measuring with a simpler device specialized for measuring the maximum water level have also been proposed. For example, a device using a float as a water level indicator (such as JP 2007 - 170886 A: Patent Document 1), a device using a plurality of water containers as a water level indicator (such as JP 10 - 122930 A: Patent Document 2), etc. have been proposed. The device described in Patent Document 1 measures the maximum water level in a manhole, etc., and the device described in Patent Document 2 measures the maximum groundwater level.

[0007] Furthermore, Japanese Utility Model Publication No. 58-125829 (Patent Document 3) discloses a water level recording device equipped with a water level recording element whose state irreversibly changes when wet, on a water level measuring bar erected on the ground such as a riverbed. As the water level recording element, a water-soluble dye is applied in dots to both ends of a cotton swab, and the dye permeates and diffuses when submerged in water, thereby providing a water level recording function. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2007-170886 [Patent Document 2] Japanese Patent Application Publication No. 10-122930 [Patent Document 3] Japanese Utility Model Publication No. 58-125829 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, to the best of the applicants' knowledge, none of the devices described in Patent Documents 1, 2, and 3 have been commercialized, and even though their configurations are simplified, there is a problem in that they cannot be easily implemented in agricultural production and other field settings. Furthermore, the apparatus described in Patent Document 3 has drawbacks in terms of ease of handling and implementation in agricultural production and other fields, as 1) it requires the replacement of the submerged water level recording element each time a measurement is taken, and 2) it requires water-soluble dyes, etc.

[0010] The object of the present invention is to provide a method for more easily measuring the highest groundwater level in soil, and a device for measuring the highest groundwater level, specifically for measuring the highest groundwater level in soil. [Means for solving the problem]

[0011] To solve the above problems, the inventors of this invention discovered that once something is wet in soil, it does not dry easily, and thus completed the present invention. The scope of this invention includes, for example, the following:

[0012] (1) A maximum groundwater level measuring device used by being installed inside a cylindrical member, comprising: a long support rod; and a plurality of recording members provided at intervals along the longitudinal direction of the support rod, the recording members having a reversible change in appearance between a wet state and a dry state. (2) A method for measuring the highest groundwater level, using a highest groundwater level measuring device comprising a long support rod and a plurality of recording members provided at intervals along the longitudinal direction of the support rod, the recording members having a reversibly changing appearance when wet, the method comprising an insertion step of inserting the highest groundwater level measuring device into a hole drilled vertically in the ground, and a measurement step of measuring the highest groundwater level for the period after the insertion step based on traces of the recording members having changed appearance when wet. [Effects of the Invention]

[0013] According to one aspect of the present invention, by specializing in the measurement of the highest groundwater level in soil, the highest groundwater level can be measured more easily. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1(a) shows a first embodiment of the maximum groundwater level measuring device of the present invention, and Figure 1(b) shows another embodiment of the maximum groundwater level measuring device. [Figure 2] Figure 2 illustrates an example of the installation of the maximum groundwater level measuring device and the measurement of the maximum groundwater level. (a) shows the state of the maximum groundwater level measuring device of the present invention when it is installed, (b) shows the state when the water level has risen, and (c) shows the state when the water level has fallen after rising. [Figure 3] Figure 3 shows an example of a maximum groundwater level measuring device with a scale of 6. [Modes for carrying out the invention]

[0015] [Embodiment 1] Hereinafter, one embodiment of the present invention will be described with reference to the attached drawings.

[0016] [1. Maximum groundwater level measuring device] (Overview) Figure (a) of Fig. 1 is a diagram showing the schematic configuration of the maximum groundwater level measuring device 1. The maximum groundwater level measuring device 1 includes a support rod 2 and a plurality of recording members 3 provided on the support rod 2. Here, in this specification, the combination of the support rod 2 and the recording members 3 provided on the support rod 2 is referred to as the main body 8 (see (b) of Fig. 1). The maximum groundwater level measuring device 1 further includes a cylindrical member 4 for housing the main body 8 therein. Furthermore, it includes a handle 5 for fixing the main body 8 to the cylindrical member 4.

[0017] (Support rod) The support rod 2 is in a long shape (such as a rod shape), and has a size that can be inserted into a hole vertically opened in the ground (hereinafter referred to as the "groundwater level measurement hole"). Examples of the material of the support rod 2 include plastic or metal. From the viewpoints of having strength, no risk of corrosion, etc., and no water absorption, a rod made of plastic (resin) or a resin-coated rod is preferable. Among the materials used in agricultural fields, for example, a plastic rod such as a dampole used as a support for an agricultural tunnel is a preferable example of the support rod 2.

[0018] The length of the support rod 2 is not particularly limited and is determined in consideration of the depth of the root zone of the crop, etc. In agricultural fields, although it depends on the type of crop planned to be cultivated, the length of the support rod 2 is preferably in the range of 50 cm to 100 cm.

[0019] A handle 5 is provided at one end 2a of the support rod 2. The handle 5 is in the shape of a frustum of a cone and has a taper whose cross-sectional diameter decreases from the one end 2a side to the other end 2b side of the support rod 2. The maximum value of the cross-sectional diameter of the handle 5 is larger than the diameter of the opening of the cylindrical member 4, and the minimum value of the cross-sectional diameter of the handle 5 is smaller than the diameter of the opening of the cylindrical member 4. The handle 5 serves as a handle when the user inserts the main body 8 into the cylindrical member 4, and in the state where the main body 8 is inserted into the cylindrical member 4, it becomes a lid that fits into the opening at one end of the cylindrical member 4, fixes the positional relationship between the main body 8 and the cylindrical member 4, and prevents rainwater from flowing into the cylindrical member 4. The handle 5 is preferably made of silicone or rubber.

[0020] (Recording member) A plurality of recording members 3 are installed at intervals along the longitudinal direction of the support rod 2. The recording member 3 is made of a material whose appearance changes when wet with water. Such materials include, but are not limited to, 1) those visible from a change in color tone due to water absorption, or 2) those visible from a change in shape due to expansion by water absorption, etc. As the groundwater level rises in the groundwater level measurement hole into which the main body 8 is inserted, the recording member 3 closest to the bottom of the groundwater level measurement hole (the recording member 3 on the other end 2b side of the support rod 2) sequentially comes into contact with the groundwater. When even a part of the recording member 3 comes into contact with the groundwater, the entire recording member 3 in contact with the groundwater gets wet due to capillary action, and its appearance changes.

[0021] The recording member 3 is made of a material whose appearance reversibly changes between a wet state and a dry state with water. Examples of such materials include fibrous bodies such as paper and cloth, sponges, and diatomaceous earth as members whose color tone changes due to water absorption, and water-absorbing polymers as members whose shape changes due to water absorption. From the viewpoints of easy availability and easy installation, fibrous bodies are preferred. Note that for recording the highest water level in a river or the like, a material whose appearance reversibly changes between a wet state and a dry state with water (that is, a material that returns to its appearance before getting wet after natural drying from the wet state) is not suitable. This is because the record of the highest water level (wet state) will disappear due to subsequent natural drying. On the other hand, as found by the inventors of the present application, in the soil, once something gets wet with water, it does not easily dry, so the record of the highest water level is easily retained without disappearing, and there is no need to separately use a water-soluble dye or the like to retain the record.

[0022] The recording member 3 is preferably in a thin form, such as a sheet or a coated form (diatomaceous earth powder, etc.), so that the main body 8 can be easily inserted into the cylindrical member 4 or the groundwater level measurement hole. Sheet-type fibrous materials are readily available, for example, as newspaper, kitchen paper, kitchen towels, or Kimtowels (product name, Crecia Co., Ltd.). Each recording member 3 is attached along the outer circumference of the support rod 2; for example, if it is a sheet-type fibrous material, it is wrapped around the outer circumference of the support rod 2. The recording member 3 may be attached to the support rod 2 using adhesive, adhesive seals, or double-sided tape.

[0023] The length (vertical width) of each recording member 3 in the longitudinal direction of the support rod 2, and the spacing between adjacent recording members 3-3, can be appropriately set according to the required accuracy of the water level recording. To prevent water movement between recording members 3-3, the spacing between adjacent recording members 3-3 must be 0.1 cm or more, and approximately 0.5 cm is preferable.

[0024] The length (vertical width) of each recording member 3 depends on the required accuracy of the water level recording, but approximately 2 cm is preferable. If the length of recording member 3 is 2.0 cm and the spacing between recording members 3-3 is 0.5 cm, the highest groundwater level will be measured in 2.5 cm increments.

[0025] The length of each recording member 3 and the spacing between adjacent recording members 3-3 may be the same length and spacing along the entire length of the support rod 2, but they may also be different in some areas. For example, in areas where more accurate water level recording is required, the length of each recording member 3 and the spacing between adjacent recording members 3-3 may be set to be shorter. Furthermore, while it is preferable to install the recording members 3 along the entire length of the support rod 2, they may be omitted in areas where water level recording is not necessary.

[0026] (Cylindrical member) The cylindrical member 4 is a tube with both ends open, preferably a cylindrical tube. Multiple holes (through holes 7) are provided from the top end to the bottom end of the cylindrical member 4, penetrating from the outside to the inside, so that groundwater can flow inside the cylindrical member 4. To prevent insects such as slugs from entering the inside of the cylindrical member 4 through the through holes 7, it is preferable to attach a net (mesh) to the through holes 7. The cylindrical member 4 is sized so that the main body 8 can be inserted through the opening at one end and accommodated inside. The inner diameter (mouth diameter) of the cylindrical member 4 is larger than the rotation diameter of the main body 8 (the rotation diameter around the main body 8 as an axis). The outer diameter of the cylindrical member 4 is not particularly limited, but it does not need to be larger than necessary for water level measurement, and is preferably about 2 cm. To allow the main body 8 inserted inside to be visible, it is preferable that the cylindrical member 4 be transparent. Among the materials used in agricultural fields, for example, a resin pipe made of polyvinyl chloride is a preferred example of the cylindrical member 4.

[0027] When the main body 8 is inserted into the cylindrical member 4, the main body 8 is fixed to the cylindrical member 4 approximately coaxially via the handle 5. Furthermore, since the handle 5 acts as a lid that closes the opening at one end of the cylindrical member 4, it blocks the intrusion of water from above (rainwater, irrigation water, etc.) and allows for accurate detection of the groundwater level.

[0028] (A form of device without a cylindrical member) Figure 1(b) shows a simpler configuration, consisting of a support rod 2 and a recording member 3 (i.e., the main body 8) of the highest groundwater level measuring device 1 (see Figure 1(a)). The highest groundwater level measuring device 1a (main body 8) can also record the highest groundwater level by being inserted into the groundwater level measurement hole. The highest groundwater level measuring device 1a may have a component on the support rod 2 that corresponds to the handle 5 of the highest groundwater level measuring device 1. In that case, when the highest groundwater level measuring device 1a is inserted into the groundwater level measurement hole, the handle 5 acts as a lid that closes the entrance to the groundwater level measurement hole, fixing the positional relationship between the highest groundwater level measuring device 1a and the groundwater level measurement hole. Measurement in the form of a device without a cylindrical member 4 is applicable when the soil on the wall surface of the groundwater level measurement hole does not collapse.

[0029] [2.Measurement method] One embodiment of the measurement method of the present invention is, for example, a method for measuring the highest groundwater level within a predetermined period using a highest groundwater level measuring device. This measurement method includes 1) an insertion step of inserting a highest groundwater level measuring device into a hole (groundwater level measuring hole) drilled vertically in the ground, and 2) a measurement step of measuring the highest groundwater level for the period after the insertion step based on the water-wetting marks on the highest groundwater level measuring device. As the highest groundwater level measuring device, a device is used that comprises a long support rod and multiple recording members provided at intervals along the longitudinal direction of the support rod, the recording members whose appearance reversibly changes when wet. For example, the highest groundwater level measuring device 1(1a) shown in Figures 1(a) and 1(b) can be used. Below, a method for measuring the highest groundwater level using the highest groundwater level measuring device 1 will be specifically described based on Figure 2. Note that in Figure 2, the handle 5 and through-hole 7 of the highest groundwater level measuring device 1 are omitted from the description.

[0030] (Groundwater level measurement hole) The hole (groundwater level measurement hole) 10 is a hole drilled vertically into the ground. The hole 10 may be an existing hole, or it may be formed by the person performing the measurement using any method they wish. When forming the hole 10, for example, straight pipes (outer diameter φ25 mm or φ22 mm) or single pipes (outer diameter φ48 mm) that are normally provided in the field may be reused. Specifically, these pipes are driven into the ground to the desired depth using a driving tool, and the hole 10 is formed by pulling out the pipe. The depth of the hole 10 is determined by considering the depth of the crop's root zone, etc., similar to the length of the maximum groundwater level measurement device 1. The depth of the hole 10 is preferably in the range of 50 cm to 100 cm.

[0031] The diameter of the hole 10 should be such that the maximum groundwater level measuring device 1 can be inserted into the hole 10 without difficulty. However, in order to maintain the upright position of the maximum groundwater level measuring device 1 inserted into the hole 10, the diameter of the hole 10 is preferably 5 cm or less.

[0032] The location where the hole 10 is installed is not particularly limited, as long as it is a place where you want to measure the highest groundwater level. However, if rainwater enters the hole 10 directly, it is preferable to install a rain cover over the hole 10. It is also preferable to install it in a location where rainwater or irrigation water accumulated on the ground does not flow into the hole 10 via the ground surface.

[0033] (Installation of the highest groundwater level measuring device (insertion process)) As shown in Figure 2(a), the highest groundwater level measuring device 1 is inserted into the hole 10. The main body 8 may be inserted into the cylindrical member 4 after inserting the cylindrical member 4 into the hole 10, or the cylindrical member 4 and the main body 8 may be inserted into the hole 10 as a single unit. One end of the highest groundwater level measuring device 1 is above ground (above the ground surface position (measurement starting point: arrow A in Figure 2)), and the other end is at the bottom of the hole 10, below the measurement starting point (underground). The cylindrical member 4 of the highest groundwater level measuring device 1 may be marked with the ground surface position (measurement starting point: arrow A in Figure 2) when installed in the hole. Alternatively, if the cylindrical member 4 is configured to have a scale 6 pre-installed (Figure 3), the scale 6 corresponding to the ground surface position may be read and recorded. Note that in Figure 3, the handle 5 and through hole 7 of the highest groundwater level measuring device 1 are omitted from the description.

[0034] (Measurement of the highest groundwater level (measurement process)) As shown in Figures 2(b) and (c), the maximum groundwater level measuring device 1 is fixed and held in the hole 10 for a certain measurement period. Each recording member 3 absorbs groundwater rising from the bottom of the hole 10, starting with those positioned lower down (closer to the bottom of the hole 10). The water-soaked recording members 3 have a different appearance than before they were wet. After being held in the hole 10 for a certain measurement period, the maximum groundwater level measuring device 1 or the main body 8 is removed from the hole 10. The measurement period is set appropriately depending on the purpose of the measurement. For example, if you want to measure the maximum groundwater level during the rainy season, the measurement period will be about two months. If you want to measure the maximum groundwater level after each rainfall, install the maximum groundwater level measuring device 1 in the hole 10 before the rain starts, remove the main body 8 from the hole 10 after the rainfall ends, and measure the maximum groundwater level. After drying the main body 8, insert it into the cylindrical member 4 that was left in the hole 10, and measure the maximum groundwater level for the next rainfall.

[0035] As the groundwater level rises and falls, it moves freely up and down inside the hole 10, and the wet position (real-time wet position) of the recording member 3 of the highest groundwater level measuring device 1 moves up and down accordingly. As shown in Figures 2(b) and (c), the wet position indicating the groundwater level in the measurement area fluctuates during the set measurement period. However, since soil does not dry easily once it is wet, the position where the groundwater level in the hole 10 rose the highest (measured water level: B) remains displayed as a trace of the recording member 3 remaining wet even after the water level has fallen, and the distance between the measured water level position: B and the ground surface position (measurement starting point): A is considered to be the highest groundwater level in the measurement area.

[0036] In another embodiment, the highest groundwater level measuring device 1 may have a scale for easily measuring the distance between the measurement water level position B and the measurement starting point A. The distance between the measurement water level position B and the ground surface position (measurement starting point A) can be measured with a measuring tape or the like after removing it from the hole 10, but by attaching a scale 6 to the transparent resin of the cylindrical member 4 of the highest groundwater level measuring device 1, the water-wetting traces of the recording member 3 can be confirmed through the transparent cylindrical member 4 (Figure 3). Alternatively, the recording member 3 of the highest groundwater level measuring device 1 may itself have a measurement function as a scale.

[0037] (Reuse after measuring the highest groundwater level) The highest groundwater level measuring device 1 can be reused because, after removing the main body 8 from the cylindrical member 4 and drying the main body 8, the recording member 3 of the main body 8 returns to its state before it got wet.

[0038] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Industrial applicability]

[0039] This invention can be used, for example, to measure the highest groundwater level in the agricultural sector. [Explanation of Symbols]

[0040] 1.1a Maximum Groundwater Level Measurement Device 2 Support rod 3 Recording Member 4. Cylindrical member 5. Handle 6 divisions 7 Through hole 8 Main unit 10 holes

Claims

1. A maximum groundwater level measuring device that is installed and used inside a cylindrical member, A long support rod, Multiple recording members are provided at intervals along the longitudinal direction of the support rod, and their appearance reversibly changes between a wet state and a dry state. A maximum groundwater level measuring device equipped with the above features.

2. A method for measuring the highest groundwater level, comprising a maximum groundwater level measuring device that includes a long support rod and a plurality of recording members provided at intervals along the longitudinal direction of the support rod, the recording members whose appearance reversibly changes when wet, The process involves inserting the aforementioned highest groundwater level measuring device into a hole drilled vertically in the ground, A measurement step to measure the highest groundwater level during the period after the insertion step, based on the traces of the recording member being wet and its appearance changing; A method that includes this.

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