Groundwater flow direction and velocity meter

Abstract

To provide a groundwater flow direction and velocity meter that eliminates the need for drilling a groundwater observation well and allows anyone to easily measure, and to provide a groundwater flow direction and velocity meter that can conduct three-dimensional measurement of groundwater flow direction and velocity.SOLUTION: A groundwater flow direction and velocity meter includes a sensor rod comprising an elongated cylindrical member 1, a ferrule 2 connected to the lower end of the cylindrical member 1, a columnar member 3 extending upward from the cylindrical member 1, three types of paper sheets 4, 5, 6 inserted inside the cylindrical member 1, and two prismatic water-permeable sponges 7, 8. One side opening 10 is provided on one of the opposing surfaces of the cylindrical member 1, and the other side opening 11 is provided on the other opposing surface of the cylindrical member 1.The top sensor paper 4, the middle sensor paper 5, and the bottom sensor paper 6 are each provided with a mark indicating the north direction and a dot pattern printed with water-soluble dye ink.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to a simplified groundwater flow velocity meter that can be inserted directly into an observation site to grasp the state of groundwater flow. [Background technology]

[0002] It is necessary to measure the flow direction and velocity of groundwater for the purposes of grasping surrounding information for in-situ remediation of contaminated soil, grasping the behavior of groundwater in landslide topography, confirming that water has been stopped at construction sites, and grasping the behavior of contaminated water at nuclear power plants. Methods for measuring groundwater flow direction and velocity are broadly divided into the following four types: (1) to (4). (1) A method for estimating flow velocity using Darcy's law based on hydraulic gradient and hydraulic conductivity (2) Single-hole flow measurement method using a sensor in an existing or newly constructed observation well (3) A dedicated observation well method in which a dedicated observation well is set up and changes in electrical conductivity are observed in the observation well. (4) Using multiple wells to measure current direction and velocity from tracer movement These methods are primarily used to measure the horizontal flow direction and velocity of groundwater. Although groundwater actually flows three-dimensionally, the horizontal component dominates in groundwater flow fields on flat land, so the vertical component is usually ignored.

[0003] However, in soil experiments to reproduce the above conditions 1) to 4), such as 1) landslide areas on mountainsides, 2) areas where unsteady groundwater flow occurs, such as seepage flow into coastal sandy beaches, 3) flows with a large vertical gradient in the matrix, such as seepage flow inside embankments, and 4) areas where ground has collapsed due to sand loss, the vertical seepage component is too large to be ignored, making it necessary to understand the three-dimensional flow direction, etc. There are two types of three-dimensional groundwater flow velocity methods that have been used traditionally: (1) a method that uses ultrasound to measure the behavior of mineral particles or density-adjusted tracer particles suspended in water, and (2) a method that uses image analysis of video. However, since these methods use suspended matter as a tracer, it is necessary to estimate the vertical component of flow velocity after correcting the theoretical settling velocity based on the particle size and density. Unless the tracer density is strictly matched to the fluid, it is impossible to directly measure the vertical flow velocity of the fluid, and furthermore, a power source and a computer for analysis are also required. Therefore, conventional groundwater flow meters have a complex structure and are heavy, making them expensive, difficult to handle, and not easy to use.

[0004] Therefore, the inventors proposed a simplified groundwater flow direction and velocity meter that uses a paper sheet of a specified shape on which a specified pattern is printed with water-soluble ink or fluorescent substance as a tracer, as described in Patent Document 1 (JP Patent Publication No. 2011-185703). This groundwater flow direction and velocity meter consists of a paper sheet P2 (see Figure 4) having a dot pattern d printed with ink or the like, and a measuring device main body 1 (see Figure 2) that holds the paper sheet P2 between permeable sponges 3a, 3b installed between holding plates 2a, 2b. The groundwater flow direction and flow velocity are measured by placing the measuring device main body 1 in a cylinder 10 installed in a groundwater observation well drilled vertically to the ground surface, removing and drying the paper sheet P2 after a predetermined time has elapsed, and determining the groundwater flow direction and flow velocity from the direction and length of tailings d' of ink, etc. (see Figures 1 and 6 and paragraphs 0034-0035 in particular). In this way, the groundwater flow direction and velocity meter described in Patent Document 1 uses ink or the like as a tracer, so there is no need to consider density differences and it can directly measure fluid behavior.It does not require a power source during measurement work in groundwater observation wells, and is inexpensive and simple in configuration, so it has been put into practical use and is increasingly being used. However, prior to placing the measuring device main body 1, a groundwater observation well with a diameter of approximately 50 mm must be drilled vertically to the ground surface, which creates the problem that the drilling work is time-consuming and expensive. In addition, since the paper sheet P2 is placed in the groundwater observation well while being held horizontally, it is possible to measure horizontal flow, but it is not possible to measure vertical flow. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-185703 A (Patent No. 5471624 A) Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is intended to solve these problems, and its first object is to provide a groundwater flow direction and velocity meter that allows anyone to easily measure groundwater flow direction and velocity using water-soluble ink or the like as a tracer, and that does not require the excavation of a groundwater observation well prior to measurement work. A second object of the present invention is to provide a groundwater flow direction and velocity meter capable of measuring groundwater flow direction and velocity in three dimensions using water-soluble ink or the like as a tracer. [Means for solving the problem]

[0007] The groundwater flow direction and velocity meter of the invention according to claim 1 comprises a sensor rod having a cylindrical member, a ferrule connected to a lower end of the cylindrical member, a columnar member extending upward from an upper end of the cylindrical member, and a paper sheet and a water-permeable sponge inserted inside the cylindrical member; The cylindrical member is made of a water-permeable body or a water-impermeable body having a large number of through holes, The paper sheet is provided with a dot pattern consisting of one or more dots printed with a water-soluble ink or a fluorescent material; By inserting the sensor rod into the ground where groundwater is to be observed and leaving it there for a predetermined period of time, it is possible to determine the flow direction and flow velocity of the groundwater based on the tailing of ink or fluorescent material that dissolves from the one or more points and is plotted on the paper sheet.

[0008] The invention according to claim 2 is the groundwater flow direction and velocity meter according to claim 1, The water-permeable sponge is made of a plurality of columnar water-permeable sponges that can be inserted into the tubular member, the paper sheet is made of an intermediate sensor paper sandwiched and held between the plurality of pillar-shaped water-permeable sponges; Based on the ink or fluorescent substance tailings drawn on the intermediate sensor paper, it is possible to determine the groundwater flow direction and flow velocity in two dimensions.

[0009] The invention according to claim 3 is the groundwater flow direction and velocity meter according to claim 1, the paper sheet comprises a top sensor paper held on the top of the water-permeable sponge and a bottom sensor paper held on the bottom of the water-permeable sponge; It is possible to determine the groundwater flow direction and flow velocity in three dimensions based on the tailings of ink or fluorescent material drawn on the top sensor paper and the tailings of ink or fluorescent material drawn on the bottom sensor paper.

[0010] The invention according to claim 4 is the groundwater flow direction and velocity meter according to claim 1, the sensor rod further includes a columnar body fixed inside the cylindrical member, The cylindrical member and the columnar body have the same central axis, The paper sheet is made of a shaft sensor paper that is held on the side of the columnar body, The stem sensor paper is provided with a dot pattern in which a plurality of dots printed with a water-soluble ink or a fluorescent material are arranged around the side surface of the columnar body; the water-permeable sponge is a cylindrical water-permeable sponge that can be inserted into the cylindrical member and arranged around the columnar body; It is possible to determine the groundwater flow direction and flow velocity in three dimensions based on multiple ink or fluorescent substance tailings drawn on the axial sensor paper. Effect of the Invention

[0011] According to the groundwater flow direction and velocity meter of the invention of claim 1, the sensor rod has a cylindrical member, a ferrule connected to the lower end of the cylindrical member, and a columnar member extending upward from the upper end of the cylindrical member, and since the sensor rod can be directly inserted into the ground, there is no need to excavate a groundwater observation well prior to measurement work. In addition, the tubular member is composed of a water-permeable body or a non-water-permeable body with numerous holes, a paper sheet and a water-permeable sponge are inserted inside, and the paper sheet is provided with a dot pattern consisting of one or more dots printed with water-soluble ink or fluorescent substance.By inserting the sensor rod into the ground where the groundwater is to be observed and leaving it to stand for a predetermined period of time, the flow direction and flow velocity of the groundwater can be determined based on the tailings of ink or fluorescent substance that dissolve from the dot pattern and are drawn on the paper sheet, and there is no need to prepare a power source. Therefore, anyone can easily measure the flow direction and flow velocity of groundwater even in mountainous regions, remote areas, developing countries, and other places where it is difficult to obtain power.

[0012] According to the groundwater flow direction and velocity meter of the invention of claim 2, in addition to the effects of the invention of claim 1, the permeable sponge consists of a plurality of columnar permeable sponges that can be inserted inside a tubular member, and the paper sheet consists of intermediate sensor paper that is sandwiched and held between the plurality of columnar permeable sponges, and the groundwater flow direction and flow velocity can be determined two-dimensionally based on the tailings of ink or fluorescent substance drawn on the intermediate sensor paper, so that the groundwater flow conditions can be easily measured with a very simple configuration.

[0013] According to the groundwater flow direction and velocity meter of the invention of claim 3, in addition to the effects of the invention of claim 1, the paper sheet consists of a top sensor paper held on the top of the permeable sponge and a bottom sensor paper held on the bottom of the permeable sponge, and the groundwater flow direction and flow velocity can be determined three-dimensionally based on the ink or fluorescent substance tailings drawn on the top sensor paper and the ink or fluorescent substance tailings drawn on the bottom sensor paper, so that the three-dimensional flow conditions of groundwater can be easily measured with a simple configuration.

[0014] According to the groundwater flow direction and velocity meter of the invention of claim 4, in addition to the effects of the invention of claim 1, the sensor rod further has a cylinder fixed inside the tubular member, the central axes of the cylinder and the cylinder are coaxial, the paper sheet consists of an axial sensor paper held on the side of the cylinder, and the axial sensor paper is provided with a dot pattern in which multiple dots printed with water-soluble ink or fluorescent substance are arranged around the side of the cylinder, and the permeable sponge consists of a tubular permeable sponge that can be inserted inside the tubular member and arranged around the cylinder, and the groundwater flow direction and flow velocity can be determined three-dimensionally based on the multiple ink or fluorescent substance tailings drawn on the axial sensor paper, so that the three-dimensional flow conditions of the groundwater can be easily and reliably measured without soiling the axial sensor paper. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a structure of a groundwater flow direction and velocity meter according to a first embodiment. [Diagram 2] 4A to 4C are diagrams showing dot patterns and the like printed on three types of paper sheets in Example 1. [Diagram 3] 1 is a graph showing the relationship between flow velocity and tailing length obtained from a laboratory experiment. [Figure 4] A diagram showing an experiment to determine the relationship between vertical flow direction and tailing direction. [Diagram 5] 5 is a graph showing the relationship between vertical flow direction and tailings direction obtained from the experiment in Figure 4. [Figure 6] FIG. 13 is a diagram showing the structure of a groundwater flow direction and velocity meter according to a second embodiment. [Figure 7] FIG. 11 is a diagram showing dot patterns and the like printed on the intermediate sensor paper of Example 2. [Figure 8] FIG. 13 is a diagram showing the structure of a groundwater flow direction and velocity meter according to a third embodiment. [Figure 9] FIG. 13 is a diagram showing dot patterns and the like printed on the shaft sensor paper of Example 3. [Figure 10] FIG. 13 is a diagram showing the occurrence of tailing in the shaft sensor paper after measurement. [Figure 11] An example of a groundwater flow model on the surface of the axial sensor paper. [Figure 12] 1 is an explanatory diagram of the azimuth distribution and approximate curve of the horizontal component Lx of the tailing length L. [Figure 13] FIG. 1 is an explanatory diagram of the azimuth distribution of the vertical component Lz of the tailing length L and an approximate straight line. [Figure 14] A diagram showing the relationship between groundwater flow velocity V and tailing length L. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiments of the present invention will be described with reference to examples. EXAMPLES

[0017] FIG. 1 is a diagram showing the structure of a groundwater flow direction and velocity meter according to the first embodiment, and FIG. 2 is a diagram showing dot patterns and the like printed on three types of paper sheets 4, 5, and 6 in the first embodiment. As shown in Figure 1, the groundwater flow direction and velocity meter of Example 1 comprises a long, slender tubular member 1 (8 cm long) with a square cross section (15 mm on each side) cut along a plane perpendicular to the central axis, a pyramidal ferrule 2 (4 cm long) connected to the lower end of the tubular member 1, a long, columnar member 3 (20 to 90 cm long) extending upward from the upper end of the tubular member 1, and a sensor rod 9 having three types of paper sheets 4, 5, 6 and two rectangular columnar water-permeable sponges 7, 8 (13 mm x 13 mm x 40 mm) inserted inside the tubular member 1. The tubular member 1, ferrule 2 and columnar member 3 are made of metal, and it is better to use a light metal such as aluminum for the tubular member 1 and columnar member 3, and a high-strength metal such as stainless steel, iron or titanium for the ferrule 2. A rectangular parallelepiped section is formed at the top of the ferrule 2 as a bottom cover that can be inserted into the lower end of the tubular member 1, and although not shown, the ferrule 2 can be fixed to the side of the tubular member 1 with two or more screws. Furthermore, in the first embodiment, the two prismatic water-permeable sponges 7 and 8 are made of melamine foam, but any material may be used as long as it is a highly water-permeable sponge. When the prismatic water-permeable sponges 7, 8 are inserted into one opposing surface of the tubular member 1, a one-side opening 10 is provided extending from the top of the upper prismatic water-permeable sponge 7 to the centre of the lower prismatic water-permeable sponge 8, and the other opposing surface of the tubular member 1 is provided with an other-side opening 11 extending from the centre of the upper prismatic water-permeable sponge 7 to the bottom of the lower prismatic water-permeable sponge 8.

[0018] 2 is a diagram illustrating three types of paper sheets 4, 5, and 6, namely, top sensor paper 4 (12 mm x 40 mm) held on the top of prismatic water-permeable sponge 7 arranged on the upper side, middle sensor paper 5 (12 mm x 12 mm) sandwiched and held between prismatic water-permeable sponge 7 arranged on the upper side and prismatic water-permeable sponge 8 arranged on the lower side, and bottom sensor paper 6 (12 mm x 40 mm) held below prismatic water-permeable sponge 8 arranged on the lower side. Each will be described in detail below. (1) The top sensor paper 4 is a rectangular drawing paper as shown in FIG. 2(A), and has two valley fold lines 12 and 13 so that it can be folded into a U-shape. There is a wedge-shaped notch 14 in the center, a dot pattern 15 (diameter 2 to 3 mm) consisting of a single dot printed with water-soluble dye ink in the center of the upper end of the square area to the left of the valley fold line 12, and a dot pattern 16 (diameter 2 mm) consisting of a single dot printed with dye ink in the center of the lower end of the square area to the right of the valley fold line 13. (2) The intermediate sensor paper 5 is a square piece of drawing paper as shown in FIG. 2(B). An N mark 17 is provided in the center of the top edge, and a dot pattern 18 (diameter 2 mm) consisting of one dot printed with dye ink is provided in the center of the drawing paper. (3) The bottom sensor paper 6, as shown in FIG. 2(C), is of the same size and material as the top sensor paper 4, and has two valley fold lines 19, 20, a wedge-shaped notch 21, and dot patterns 22, 23 (diameter 2 to 3 mm) as in FIG. 2(A). However, the orientation of the wedge cutout 21 is 90 degrees different from the wedge cutout 14 in the top sensor paper 4 .

[0019] Next, a method for measuring the flow direction and flow velocity of groundwater using the sensor rod 9 will be described. (Step 1) Loosen the screw and remove the ferrule 2 fixed to the lower end of the sensor rod 9. (Step 2) Fold the top sensor paper 4 along the valley folds 12, 13 and turn it upside down. (Step 3) Cover the top of the prismatic water-permeable sponge 7 placed on the upper side with the top sensor paper 4, and insert it into the tubular member 1 so that the wedge-shaped notch 14 points toward north. (Step 4) Place the intermediate sensor paper 5 over the top surface of the prismatic water-permeable sponge 8 placed underneath, with the N mark 17 facing north. (Step 5) Fold the bottom sensor paper 6 along the valley fold lines 19 and 20. (Step 6) The bottom sensor paper 6 is placed over the lower part of the prismatic water-permeable sponge 8 arranged below, with the wedge-shaped cutout 21 facing north, and then inserted into the cylindrical member 1. (Step 7) Insert the rectangular parallelepiped portion (bottom cover) at the top of the ferrule 2 into the bottom end of the cylindrical member 1, and secure it in place by tightening the screws from the side of the cylindrical member 1 (sensor rod 9 is ready).

[0020] (Step 8) At the location where the groundwater flow direction and flow velocity are to be measured, an aluminum rod (not shown) is inserted vertically to the specified depth to confirm that it can penetrate into the ground. (Step 9) Ground with low permeability (10 -5 m / sec or less), in order to stabilize the groundwater level at the time of penetration, the sensor rod 9 (dummy sensor) excluding the three types of paper sheets 4, 5, 6 and the two rectangular columnar permeable sponges 7, 8 is inserted to a specified depth and waited. In addition, if the permeability coefficient of the ground is 10 -5 m / sec for 10 minutes, 10 -6 In the case of m / sec, a waiting time of about one hour is required, and in ground with a permeability coefficient lower than that, the flow velocity becomes extremely small and cannot be measured. (Step 10) Pull out the aluminum rod or dummy sensor (ground confirmation completed).

[0021] (Step 11) Once it has been confirmed that the sensor rod 9 can be inserted into the ground, insert the sensor rod 9, into which the three types of paper sheets 4, 5, and 6 and the two rectangular columnar water-permeable sponges 7 and 8 have been inserted, vertically to the specified depth along the hole made after the aluminum rod was removed. Note that the sensor rod 9 is inserted after determining its orientation so that the wedge-shaped notches 14 and 21 and the N mark 17 face north, and a spirit level is used to make sure the central axis of the sensor rod 9 is vertical. (Step 12) Record the following: (1) Magnetic direction of the installation location, (2) Measurement start time, (3) Measurement location, (4) Measurement depth, and (5) Serial numbers of paper sheets 4, 5, and 6. (Step 13) Leave it to stand for 15, 30 or 60 minutes. It is better to leave it to stand for 60 minutes first, judge the approximate flow rate, decide on the time to leave it, and then perform the actual measurement. (Step 14) After the measurement is completed, pull up the sensor rod 9, loosen the screw, remove the ferrule 2, and collect the paper sheets 4, 5, and 6.

[0022] (Step 15) The collected paper sheets 4, 5, and 6 are dehydrated with blotting paper and then sealed in small containers containing desiccants. (Step 16) After measurement, insert a sensor that measures electrical conductivity (hereinafter referred to as the "EC sensor") or a pH sensor into the hole to measure the water quality. (Step 17) After measuring, measure and record the groundwater depth from the surface of the hole with a tape measure or similar, or insert a dummy sensor into the hole after measuring, insert a tube into it and blow into the tube, then measure and record the length at which the sound stops. In the latter case, measurements are repeated until the water level stabilizes, and the difference from the ground surface to the highest point of the dummy sensor and the difference from the highest point of the dummy sensor to the water level (where the sound stops) when the water level has stabilized are measured and recorded.

[0023] (Step 18) Remove the paper sheets 4, 5, and 6 from the containers, dry them in an oven, and then attach them to the data sheet with double-sided tape or adhesive. (Step 19) The data sheet with the dried paper sheets 4, 5, and 6 attached is scanned with a scanner, the image data is input into a computer, and the tailing direction and length are measured by image analysis (measurement of tailing will be described later). A digital camera may be used to capture image data of the paper sheets 4, 5, and 6. In this case, it is not necessary to dry the paper sheets 4, 5, and 6 sufficiently, and image data can be captured even in a wet state. Alternatively, the outline of the tailing may be defined visually without acquiring image data, and the tailing direction and length may be read. (Step 20) Based on the measured tailings direction and tailings length, the groundwater flow direction and flow velocity are determined three-dimensionally. Specifically, the horizontal flow direction and flow velocity can be determined based on the tailings direction and tailings length measured by the middle sensor paper 5, the north-south and vertical flow direction and flow velocity can be determined based on the tailings direction and tailings length measured by the top sensor paper 4, and the east-west and vertical flow direction and flow velocity can be determined based on the tailings direction and tailings length measured by the bottom sensor paper 6. Regarding the flow direction, it is possible to directly determine the flow direction in each direction from the tailing direction, but regarding the flow velocity, it is necessary to determine the relationship between the tailing length and the flow velocity in advance. Furthermore, when measuring flow direction and flow velocity, it is better to insert the sensor rod 9 into the same depth position of one measurement hole while replacing the paper sheets 4, 5, and 6 to take multiple measurements, and then compile and average the results to determine the flow direction and flow velocity.

[0024] FIG. 3 is a graph showing the relationship between flow velocity and tailing length obtained from a laboratory experiment. The indoor experiments were carried out in a tank filled with silica sand No. 5, where horizontal flows with Darcy flow velocities of 0.05, 0.1 and 0.2 cm / min in a north-south direction were created in the silica sand No. 5, and a sensor rod 9 was placed vertically in the silica sand No. 5 in which each horizontal flow had been created and left to stand for 15 minutes. After that, the tailing length of the top sensor paper 4 removed from the sensor rod 9 was measured. In FIG. 3 showing the experimental results, the vertical axis represents the tailing length (cm) of the top sensor paper 4, and the horizontal axis represents the Darcy flow velocity (cm / min) of the horizontal flow in the tank. From the distribution of measured values ​​showing the relationship between the north-south Darcy current velocity and the tailing length, when the north-south Darcy current velocity is x (cm / min) and the tailing length of the top sensor paper 4 is y (cm / min), a correspondence relationship represented by the calibration line defined by equation (1) can be seen. This correspondence relationship differs depending on the standing time, and equation (1) is the relationship obtained after a standing time of 15 minutes. y=0.7733x+0.0538...Equation (1) In addition, the y-intercept in Figure 3, 0.0538, indicates the diffusion velocity in a no-flow state, and the coefficient of determination is 0.8365, which is close to 1, confirming that this is a highly accurate equation. It is also considered that the tailing length measured by the middle sensor paper 5 for the horizontal flow and the tailing length measured by the bottom sensor paper 6 for the east-west horizontal flow have a correspondence relationship with the Darcy velocity of each horizontal flow, which is expressed by the calibration line defined by formula (1). Therefore, at the location where the flow direction and flow velocity of groundwater are to be measured, if the sensor rod 9 is inserted vertically to a specified depth, left to stand for a specified time, and then the sensor rod 9 is pulled up and the tailing length is measured with the retrieved top sensor paper 4, middle sensor paper 5, and bottom sensor paper 6, the Darcy velocity of the horizontal flow in the north-south direction, the Darcy velocity in the horizontal direction, and the Darcy velocity of the horizontal flow in the east-west direction can be easily calculated based on the conversion using the calibration line.

[0025] FIG. 4 is a diagram showing an experiment to determine the relationship between the vertical flow direction and the tailing direction, and FIG. 5 is a graph showing the relationship between the vertical flow direction and the tailing direction obtained in the experiment of FIG. In the experiment shown in Figure 4(A), the sensor rod was placed vertically on No. 5 silica sand in a water tank with a horizontal flow of 0.11 cm / min, with the angle set to 0°, and then tilted 15°, 30°, and 45° toward the downstream side of the horizontal flow. After leaving the sensor rod stationary for 15 minutes, the inclination of the tailing of the top sensor paper removed from the sensor rod was measured. In the experiment shown in Figure 4(B), the sensor rod was placed vertically on No. 5 silica sand in a water tank with a horizontal flow of 0.11 cm / min, with the angle set to 0°, and then tilted 15°, 30°, and 45° toward the upstream side of the horizontal flow (denoted as -15°, -30°, and -45°, respectively). After leaving the sensor rod stationary for 15 minutes, the inclination of the tailing of the top sensor paper removed from the sensor rod was measured. In this experiment, instead of the top sensor paper 4 having the single-point dot patterns 15, 16 described above, a top sensor paper having four dot patterns, two on each of the upper and lower edges of Figure 2(A), was used.

[0026] In Figure 5, the tilt of the sensor rod is set as the set tilt (°), the tilt of the tailing measured at each set tilt is set as the measured tilt (°), and the measurement results are plotted on an XY plane with the X-axis representing the set tilt (°) and the Y-axis representing the measured tilt (°), and a correlation line is then drawn. As a result, a correspondence relationship is observed between the set tilt X (°) and the measured tilt Y (°), which is represented by the calibration line defined by equation (2). Y=0.9425X-5.0713...Equation (2) The Y-intercept in Figure 5, -5.0713, indicates the error in the inclination, and it can be seen that there is an error of about 5°. 2 ) is 0.9008, which is close to 1, so we can see that this is a highly accurate formula. It is also believed that the inclination of the tailings measured by the bottom sensor paper 6 with respect to the east-west horizontal flow has a corresponding relationship represented by the set inclination and the calibration line defined by formula (2). Therefore, at the location where the groundwater flow direction and flow velocity are to be measured, if the sensor rod 9 is inserted vertically to a specified depth, left to stand for a specified time, then the sensor rod 9 is pulled up and the inclination of the tailings is measured with the retrieved top sensor paper 4 and bottom sensor paper 6, the north-south vertical flow direction and the east-west vertical flow direction can be easily determined based on the measured inclination. EXAMPLES

[0027] FIG. 6 is a diagram showing the structure of the groundwater flow direction and velocity meter according to the second embodiment, and FIG. 7 is a diagram showing a dot pattern and the like printed on the intermediate sensor paper 24 of the second embodiment. As shown in Figure 6, the groundwater flow direction and velocity meter of Example 2 comprises a long and slender cylindrical member 25 (length 8 cm) with a circular cross section (diameter 26 mm) cut along a plane perpendicular to the central axis, a conical ferrule 26 (length 4 cm) connected to the lower end of the cylindrical member 25, a long and solid cylindrical member 27 (length 20 to 90 cm) extending upward from the upper end of the cylindrical member 25, and a sensor rod 30 having an intermediate sensor paper 24 inserted inside the cylindrical member 25 and two cylindrical water-permeable sponges 28, 29 (diameter 24 mm, length 40 mm). The cylindrical member 25, ferrule 26, and columnar member 27 are made of metal, and it is preferable to use a light metal such as aluminum for the cylindrical member 25 and columnar member 27, and a high-strength metal such as stainless steel, iron, or titanium for the ferrule 26. A columnar portion is formed at the top of the ferrule 26 as a bottom cover that can be inserted into the lower end of the cylindrical member 25, and although not shown, the ferrule 26 can be fixed to the side of the cylindrical member 25 with two or more screws. Furthermore, in the second embodiment, the two cylindrical water-permeable sponges 28 and 29 are made of melamine foam, but any material may be used as long as it is a highly water-permeable sponge. In addition, a number of holes (not shown) are formed in the outer wall (1 mm thick) of the cylindrical member 25, at least in the areas surrounding the upper and lower boundaries of the inserted cylindrical water-permeable sponges 28, 29, and four air vent holes 31 are provided at the upper end of the cylindrical member 25. And, like the intermediate sensor paper 5 of Example 1, the intermediate sensor paper 24 of Example 2, which is sandwiched and held between a cylindrical water-permeable sponge 28 arranged on the upper side and a cylindrical water-permeable sponge 29 arranged on the lower side, is a circular drawing paper (diameter 24 mm) as shown in Figure 7, with an N mark 32 on the upper edge and a dot pattern 33 (diameter 2 mm) consisting of one dot printed with dye ink at the center point of the circular drawing paper.

[0028] Next, a method for measuring the flow direction and flow velocity of groundwater using the sensor rod 30 will be described. It should be noted that the precautions for carrying out the procedures explained in the first embodiment are the same as those in the first embodiment, and therefore will not be repeated here. (Step 21) Loosen the screw and remove the ferrule 26 fixed to the lower end of the sensor rod 30. (Step 22) The cylindrical water-permeable sponge 28 is inserted into the cylindrical member 25. (Step 23) Place the intermediate sensor paper 24 over the top surface of the cylindrical water-permeable sponge 29 with the N mark 32 facing north, and insert it into the cylindrical member 25. (Step 24) Insert the cylindrical body portion at the top of the ferrule 26 into the bottom end of the cylindrical member 25, and fasten the screw from the side of the cylindrical member 25 to secure it in place (preparation of the sensor rod 30 is complete).

[0029] (Step 25) At the location where the groundwater flow direction and flow velocity are to be measured, an aluminum rod (not shown) is inserted vertically to the specified depth to confirm that it can penetrate into the ground. (Step 26) Ground with low permeability (10 -5 m / sec or less), in order to stabilize the groundwater level during penetration, the sensor rod 30 (dummy sensor) excluding the intermediate sensor paper 24 and the two cylindrical water-permeable sponges 28, 29 is inserted to a specified depth and waited. (Step 27) Pull out the aluminum rod or dummy sensor (ground confirmation completed).

[0030] (Step 28) Once it has been confirmed that the sensor rod 30 can be penetrated into the ground, the sensor rod 30 with the intermediate sensor paper 24 and the two cylindrical water-permeable sponges 28, 29 inserted therein is inserted vertically to a specified depth along the hole left behind by the aluminum rod or the like. (Step 29) Record the following: (1) magnetic direction of the installation location, (2) measurement start time, (3) measurement location, (4) measurement depth, and (5) serial number of the intermediate sensor paper 24. (Step 30) Leave it for 15, 30 or 60 minutes. (Step 31) After the main measurement is completed, pull up the sensor rod 30, loosen the screw, remove the ferrule 26, and retrieve the intermediate sensor paper 24.

[0031] (Step 32) The collected intermediate sensor paper 24 is dehydrated with blotting paper and then sealed in a small container containing a desiccant. (Step 33) After measurement, insert an EC sensor, pH sensor, etc. into the hole to measure the water quality, and measure and record the groundwater depth, etc. in the same manner as in Step 17 above.

[0032] (Step 34) The intermediate sensor paper 24 is removed from the container, dried in an oven, and then attached to the data sheet with double-sided tape or adhesive. (Step 35) The data sheet with the dried intermediate sensor paper 24 attached is scanned with a scanner, and the image data is input to a computer, and the tailing direction and tailing length are measured by image analysis. (Step 36) Based on the measured tailings direction and tailings length, the groundwater flow direction and flow velocity are calculated two-dimensionally. Specifically, based on the tailings direction and tailings length measured by the intermediate sensor paper 24, the horizontal flow direction and flow velocity can be calculated. The method for determining the horizontal flow direction and flow velocity based on the tailing direction and tailing length measured by the intermediate sensor paper 24 is the same as the method for determining the horizontal flow direction and flow velocity based on the tailing direction and tailing length measured by the intermediate sensor paper 5 in Example 1, so it will be omitted (see the explanation of step 20 above and Figure 3 and formula (1)). EXAMPLES

[0033] FIG. 8 is a diagram showing the structure of the groundwater flow direction and velocity meter of the third embodiment, and FIG. 9 is a diagram showing a dot pattern and the like printed on the shaft sensor paper 34 of the third embodiment. As shown in FIG. 8, the groundwater flow direction and velocity meter of Example 3 is composed of a long and slender cylindrical member 35 (length 5 cm) with a donut-shaped cross section (outer diameter 26 mm, inner cylinder diameter 13 mm) cut along a plane perpendicular to the central axis, a conical ferrule 36 (length 3 cm) connected to the lower end of the cylindrical member 35, a long and solid cylindrical member 37 (length 20 to 90 cm) extending upward from the upper end of the cylindrical member 35, a shaft sensor paper 34 that can be wrapped around the inner cylinder of the cylindrical member 35, and a sensor rod 40 having two cylindrical water-permeable sponges 38, 39 (outer diameter 24 mm, inner diameter 13 mm, length 25 mm). Here, the central axes of the cylindrical member 35 and the solid or hollow cylinder fixed inside it are coaxial, and the two cylindrical water-permeable sponges 38, 39 are each inserted inside the cylindrical member 35 and can be positioned around the cylinder and the axial sensor paper 34. The materials of the cylindrical member 35, the ferrule 36, the cylindrical member 37 and the two cylindrical water-permeable sponges 38, 39 are the same as those of the cylindrical member 25, the ferrule 26, the cylindrical member 27 and the two cylindrical water-permeable sponges 28, 29 in Example 2, and a cylindrical body portion is formed at the top of the ferrule 36, and the ferrule 36 can be fixed with screws, similar to the ferrule 26 in Example 2. Furthermore, a large number of through holes (not shown) are formed in the outer wall (thickness 1 mm) of the cylindrical member 35, and four air vent holes 41 are provided at the upper end of the cylindrical member 35. As shown in FIG. 9, the shaft sensor paper 34 is a rectangular piece of drawing paper (50 mm high, 45 mm wide) with two straight lines 42 printed on both sides in oil-based ink and a dot pattern 43 consisting of multiple dots (each 2 mm in diameter) printed on it in water-soluble dye ink using a printer or the like. When the shaft sensor paper 34 is wrapped around the inner wall of the cylindrical member 35 and the two straight lines 42 are held in place with one on top of the other, multiple dots are arranged at equal intervals around the entire circumference (for example, eight dots at 45° central angle intervals).

[0034] Next, a method for measuring the flow direction and flow velocity of groundwater using the sensor rod 40 will be described. It should be noted that the precautions for carrying out the procedures explained in the first embodiment are the same as those in the first embodiment, and therefore will not be repeated here. (Step 41) Loosen the screw and remove the ferrule 36 fixed to the lower end of the sensor rod 40. (Step 42) Wrap the shaft sensor paper 34 around the inner wall surface of the cylindrical member 35. (Step 43) The two cylindrical water-permeable sponges 38, 39 are inserted into the cylindrical member 35 to cover the outside of the shaft sensor paper 34. (Step 44) The upper cylindrical portion of the ferrule 36 is inserted into the lower end of the cylindrical member 35, and the screw is tightened from the side of the cylindrical member 35 to secure it in place (preparation of the sensor rod 40 is complete).

[0035] (Step 45) At the location where the groundwater flow direction and flow velocity are to be measured, an aluminum rod (not shown) is inserted vertically to the specified depth to confirm that it can penetrate into the ground. (Step 46) Ground with low permeability (10 -5 m / sec or less), in order to stabilize the groundwater level during penetration, the sensor rod 40 (dummy sensor) excluding the axial sensor paper 34 and the two cylindrical water-permeable sponges 38, 39 is inserted to a specified depth and waited. (Step 47) Pull out the aluminum rod or dummy sensor (ground confirmation completed).

[0036] (Step 48) Once it has been confirmed that the sensor rod 40 can be penetrated into the ground, the sensor rod 40 with the shaft sensor paper 34 and the two cylindrical water-permeable sponges 38, 39 inserted is inserted vertically to a specified depth along the hole left after the aluminum rod or the like was pulled out. (Step 49) Record the following: (1) magnetic direction at the installation location, (2) measurement start time, (3) measurement location, (4) measurement depth, and (5) serial number of the shaft sensor paper 34. (Step 50) Leave it for 15, 30 or 60 minutes. (Step 51) After the main measurement is completed, pull up the sensor rod 40, loosen the screw, remove the ferrule 36, and retrieve the shaft sensor paper 34.

[0037] (Step 52) The collected shaft sensor paper 34 is dehydrated with blotting paper and then sealed in a small container containing a desiccant. (Step 53) After measurement, insert an EC sensor, pH sensor, etc. into the hole to measure the water quality, and measure and record the groundwater depth, etc. in the same manner as in Step 17 above.

[0038] (Step 54) Remove the shaft sensor paper 34 from the container, dry it in an oven, and then attach it to the data sheet with double-sided tape or adhesive. (Step 55) The data sheet with the dried axial sensor paper 34 attached is scanned with a scanner, and the image data is input to a computer, and the tailing direction and tailing length are measured by image analysis. (Step 56) Based on the tailing direction and tailing length measured at each point, the horizontal flow direction and flow velocity as well as the vertical flow direction and flow velocity are calculated.

[0039] Next, a method for three-dimensionally determining the flow direction and flow velocity of groundwater based on the tailing direction and tailing length of each point 43 measured by the axial sensor paper 34 will be described. FIG. 10 is a diagram showing the occurrence of tailings 44 on the shaft sensor paper 34 (hereinafter referred to as "paper 34") after measurement. The sensor rod 40 was inserted into the ground, left to stand for a predetermined time, and then pulled up. The recovered paper 34 was unfolded and dried, and its surface was scanned, resulting in an example of an image obtained. In addition, the four straight lines other than the two straight lines 42, the angle indications, and the words "upstream" and "downstream" have been added to make the positional relationship between the groundwater flow and the paper 34 easier to understand.

[0040] Figure 11 shows an example of a groundwater flow model on the surface of the shaft sensor paper 34, where Figure 11(A) shows a plan view and Figure 11(B) shows a side view (for ease of explanation, the side view is shown at an angle). The tailings 44 drawn on the surface of the paper 34 as shown in Figure 10 can be modeled as shown in Figure 11, assuming that groundwater passes in a straight line through the cylindrical permeable sponges 38, 39 that surround the paper 34.

[0041] If the horizontal tangent direction on the surface of the paper 34 is x and the vertical upward direction is z, then the horizontal tangential flow velocity Vx and the vertical upward flow velocity Vz of the groundwater are expressed as follows, when the central angle between the north (reference direction) on the paper 34 and the tangent line of the horizontal tangent is φ, the upwind direction of the flow direction (azimuth angle of the groundwater flow) is ψ, the groundwater flow velocity is V, and the vertical flow direction (angle of elevation and depression) is θ: Vx=Vcosθsin(φ-ψ) ···· Formula (3) Vz=Vsinθ ······························································ Formula (4) It becomes. Therefore, the lengths Lx and Lz of the tailing 44 in the x and z directions are Lx=Lcosθsin(φ-ψ) ···· Formula (5) Lz=Lsinθ ························································ Formula (6) It becomes. Here, the groundwater flow direction (downwind) is (ψ+180°) (where the flow direction is expressed as 0° to 360°).

[0042] The groundwater flow velocity V is approximated by equations (5) and (6), L=f(V) ····································································· Formula (7) Then, from equation (7), V=f -1 (L) ·················································· Formula (8) It is required as follows. In the above, Vx should strictly be the circumferential flow velocity, but if Vx is sufficiently small, there is no problem in practical terms with considering it as the tangential flow velocity. Therefore, the length of the tailing 44 drawn on the paper 34 can be regarded as the tailing length L corresponding to the flow velocity V, and the horizontal component (horizontal length) of the tailing length L on the paper 34 can be considered as Lx, and the vertical component (vertical length) can be considered as Lz.

[0043] When determining the tailing length L and direction, the outline of the tailing 44 is defined by visual inspection or image processing from the tailing 44 drawn on the surface of the paper 34 as shown in Figure 10, and the length of each outline and the angle between the outline and the reference line are read. For example, the surface of the paper 34 is scanned by a scanner and subjected to a binarization process. The contour of the tailing 44 is defined by machine learning or the like, and the tailing length L and direction are read based on features such as the line segments connecting the center of gravity of each point of the dot pattern 43 to the center of gravity of the tailing 44 and the Feret's diameter of the tailing 44 (the long side of the rectangle circumscribing the contour of the tailing 44).

[0044] FIG. 12 is an explanatory diagram of the azimuth distribution and approximation curve of the horizontal component Lx of the tailing length L. FIG. 12 shows the results of an experiment in which the sensor rod 40 of Example 3 was inclined at 30° with respect to the vertical axis and inserted into No. 5 silica sand in the water tank shown in FIG. 4, generating a vertical flow. The relationship between the horizontal component Lx of the tailing length L of the dot pattern 43 and the angle (azimuth angle) of each point from the reference azimuth was graphed, and an approximation curve was calculated. In the model shown in FIG. 11, the experimental conditions were as follows: flow direction (downwind direction) = 180° (ψ = 0°), set flow velocity V = 0.3 cm / min, vertical flow direction (elevation angle) θ = 30°.

[0045] From the graph in Figure 12, it can be seen that the approximation curve intersects with the horizontal axis at an azimuth angle of approximately 200° to 210°, and the horizontal component Lx of the tailing length L becomes zero, which roughly coincides with the set flow direction (downwind direction) = 180°. Therefore, according to the sensor rod 40 of the third embodiment, the direction connecting two points on the paper 34 at the azimuth angle at which the horizontal component Lx of the tailing length L is zero can be regarded as the horizontal flow direction of the groundwater. Furthermore, with the sensor rod 40 of Example 3, the azimuth angle at which the horizontal component Lx of the tailing length L is maximum can be read from the graph in Figure 12, and the horizontal tangent direction on the paper 34 at the azimuth angle can be regarded as the horizontal flow direction of the groundwater. Furthermore, according to the sensor rod 40 of Example 3, the maximum value of the horizontal component Lx of the tailing length L is read from the graph in FIG. 12, and a divided value Lxd is obtained by dividing the maximum value by the sine of the elevation / depression angle. The velocity Vxd corresponding to the divided value Lxd is obtained from the calibration curve (FIG. 14, details will be described later) for the time that the sensor rod 40 is inserted into the ground and left stationary. The horizontal flow velocity Vx of the groundwater can be obtained by multiplying the velocity Vxd by the sine of the elevation / depression angle.

[0046] FIG. 13 is an explanatory diagram of the azimuth distribution of the vertical component Lz of the tailing length L and an approximation line. FIG. 13 shows a graph of the relationship between the vertical component Lz of the tailing length L of the dot pattern 43 and the angle (azimuth angle) of each point from the reference azimuth in the experiment of FIG. 12, and an approximation line was calculated. According to the graph in Figure 13, the vertical component Lz of the tailing length L is on the positive side overall, which indicates that there is a vertical upward flow in the groundwater as expected.

[0047] With the sensor rod 40 of Example 3, the maximum value of the horizontal component Lx of the tailing length L is read from the graph in FIG. 12, the vertical component Lz of the tailing length L is read from the graph in FIG. 13, and the vertical flow direction of the groundwater can be determined by dividing Lz by Lx and finding its arctangent. Furthermore, according to the sensor rod 40 of Example 3, the maximum value of the vertical component Lz of the tailing length L is read from the graph in FIG. 13, and a divided value Lzd is obtained by dividing the maximum value by the sine of the elevation / depression angle. The velocity Vzd corresponding to the divided value Lzd is obtained from the calibration curve (FIG. 14, details will be described later) for the time that the sensor rod 40 is inserted into the ground and left stationary, and the vertical flow velocity Vz of the groundwater can be obtained by multiplying the velocity Vzd by the sine of the elevation / depression angle. The groundwater flow direction and flow velocity can be calculated manually or by using image analysis software.

[0048] FIG. 14 is an example of a graph showing the relationship between groundwater flow velocity V and tailing length L on paper 34 (calibration curve). FIG. 14 shows the results of an experiment in which, as in the experiment in FIG. 12, the sensor rod 40 of Example 3 of the present invention was inclined at 30° to the vertical axis and inserted into No. 5 silica sand in the water tank shown in FIG. 4, generating a vertical flow, and the graph shows the relationship between the tailing length L and the flow velocity V at the point at the azimuth angle where the horizontal component Lx of the tailing length L on the paper 34 is at a maximum. In the model shown in Figure 11, the experiment was performed by inserting the sensor rod 40 of Example 3 into No. 5 silica sand and leaving it to stand for 15 minutes under the conditions of flow direction (downwind direction) = 180° (ψ = 0°), set flow velocity V = 0.3 cm / min, vertical flow direction (elevation angle) θ = 30°, and set flow velocity V = 0.05 cm / min, 0.1 cm / min, 0.15 cm / min, 0.2 cm / min, and 0.3 cm / min. The groundwater flow velocity V can be determined by preparing a calibration curve (calibration curve) of the relationship between flow velocity V and tailing length L as shown in Figure 14 in advance through experiments, and then fitting the tailing length L drawn on paper 34 to the calibration curve. FIG. 14 shows approximation by a curve, and although the approximation is done by a power curve here, it can also be done by a straight line.

[0049] According to the sensor rod 40 of the third embodiment, by inserting the sensor rod 40 vertically to a predetermined depth along the hole left after pulling out the aluminum rod or the like and leaving it to stand for a predetermined time, the groundwater flow direction and flow velocity can be determined three-dimensionally based on the length and direction of the tailings 44 which are dissolved from each point of the dot pattern 43 and drawn on the paper 34, so that a simplified groundwater flow direction and flow velocity meter can be provided which does not require the digging of a groundwater observation well.

[0050] Modifications of the groundwater flow direction and velocity meters of Examples 1 to 3 are listed below. (1) In Examples 1 to 3, the size of each part is shown in parentheses, but these sizes are approximate and are not limited to these sizes. In particular, the length of the columnar member 3 and the cylindrical members 27 and 37 needs to be appropriately adjusted depending on the location where the groundwater flow is measured. (2) The paper sheets 4, 5, and 6 in Example 1, the intermediate sensor paper 24 in Example 2, and the shaft sensor paper 34 in Example 3 were all drawing paper, but paper other than drawing paper may be used as long as it has consideration for durability against water and suitability for dye ink migration. (3) Although dot patterns were printed with dye ink on the paper sheets 4, 5, and 6 in Example 1, the intermediate sensor paper 24 in Example 2, and the shaft sensor paper 34 in Example 3, water-soluble ink or fluorescent material may be used instead of dye ink. In addition, dot patterns 15, 16, 18, 22, 23, and 33 consisting of one dot were provided on the left side of valley fold line 12 and the right side of valley fold line 13 of the top sensor paper 4 in Example 1, the left side of valley fold line 19 and the right side of valley fold line 20 of the intermediate sensor paper 5 and the bottom sensor paper 6 in Example 1, and the intermediate sensor paper 24 in Example 2, but dot patterns consisting of multiple dots may be provided in each area.

[0051] (4) The sensor rod 9 in Example 1 had an elongated tubular member 1 having a square cross-section taken along a plane perpendicular to the central axis, and a long columnar member 3 extending upward from the upper end of the tubular member 1, but the cross-sectional shape of the tubular member 1 may be rectangular, circular, or elliptical. Furthermore, the columnar member 3 in the first embodiment may be partially or entirely hollow, and in such a case, the hollow portion may be integrated with the tubular member 1 . (5) In Example 1, a one-side opening 10 was provided on one opposing surface of the tubular member 1, and an other-side opening 11 was provided on the other opposing surface of the tubular member 1. However, without providing the one-side opening 10 and the other-side opening 11, the entire tubular member 1 may be made of a water-permeable body having a certain degree of strength, or the entire tubular member 1 may be made of a non-water-permeable tube made of metal, reinforced plastic, etc., and a number of through holes may be formed in the side portion. (6) In Example 1, the tubular member 1 was provided with an opening 10 on one side and an opening 11 on the other side, and the sensor rod 9 was simply inserted into the ground to measure the flow direction and flow velocity of the groundwater. However, it is better to cover the periphery of the opening 10 on one side and the opening 11 on the other side with nonwoven fabric or the like before inserting the sensor rod 9 into the ground, as this can prevent the rectangular columnar water-permeable sponges 7, 8 from becoming dirty. (7) In the tubular member 1 of Example 1, paper sheets 4, 5, 6 and two prismatic water-permeable sponges 7, 8 were inserted, and a top sensor paper 4 was placed on top of the prismatic water-permeable sponge 7 located on the upper side, an intermediate sensor paper 5 was placed between the prismatic water-permeable sponge 8, and a bottom sensor paper 6 was placed below the prismatic water-permeable sponge 8 located on the lower side to measure the three-dimensional flow conditions of the groundwater. However, even if the intermediate sensor paper 5 is not placed, the top sensor paper 4 can be used to determine the flow direction and flow velocity in the north-south and vertical directions, and the bottom sensor paper 6 can be used to determine the flow direction and flow velocity in the east-west and vertical directions, so that the flow direction and flow velocity of the groundwater can be determined three-dimensionally. In addition, by placing only the top sensor paper 4, or by placing the surface of the intermediate sensor paper between two rectangular prismatic permeable sponges parallel to the vertical and north-south directions, the flow direction and flow velocity in the north-south and vertical directions can be determined, and by placing only the bottom sensor paper 6, or by placing the surface of the intermediate sensor paper between two rectangular prismatic permeable sponges parallel to the vertical and east-west directions, the flow direction and flow velocity in the east-west and vertical directions can be determined. Therefore, when it is sufficient to determine the groundwater flow direction and flow velocity two-dimensionally in the vertical plane, it is also possible to measure the flow direction and flow velocity in a plane parallel to the vertical line by placing only the top sensor paper 4, only the bottom sensor paper 6, or only the intermediate sensor paper. Furthermore, instead of openings on all four sides as shown in Fig. 1, it is also possible to have openings on only two opposing sides and place sensor paper only on the non-opening sides. For example, in the experiment to determine the relationship between the vertical flow direction and the tailings direction shown in Fig. 4, a sensor rod with a metal cylindrical member 1 and an opening 10 on only one side is used. If the horizontal flow direction is known, the vertical two-dimensional flow direction can also be measured by placing rectangular sensor paper as shown in Fig. 4 on the non-opening sides.

[0052] (8) Although the cylindrical members 25, 35 in Examples 2 and 3 were made of metal, the entire member may be made of a water-permeable body having a certain degree of strength, or the cylindrical member may be made of a non-water-permeable body such as reinforced plastic other than metal and have a large number of holes formed on the outer surface. (9) The sensor rod 30 of Example 2 has an elongated cylindrical member 25 having a circular cross section cut along a plane perpendicular to the central axis, and a solid columnar member 27 extending upward from the upper end of the cylindrical member 25, but the cross section of the cylindrical member 25 may have any shape, such as a polygonal shape, a circle, or an ellipse. Also, the columnar member 27 of Example 2 may be partially or entirely hollow, in which case the hollow portion may be integrated with the cylindrical member 25. (10) The sensor rod 40 of Example 3 had an elongated cylindrical member 35 having a donut-shaped cross section cut along a plane perpendicular to the central axis, and a solid columnar member 37 extending upward from the upper end of the cylindrical member 35. However, it is sufficient for the cross-sectional shape of the cylindrical member 35 to have a circular inner wall surface, and the outer wall surface may have any shape, such as a polygonal, circular, or elliptical shape. Furthermore, the columnar member 37 of the third embodiment may be partially or entirely hollow, and in such a case, the hollow portion may be integrated with the cylindrical member 35 . [Explanation of symbols]

[0053] 1 Cylindrical member 2 Ferrule 3 Pillar member 4 Top sensor paper 5 Middle Sensor Paper 6 Bottom Sensor Paper 7, 8 Prismatic water-permeable sponge 9 Sensor rod 10 One-side opening 11 other side opening 12, 13 valley fold line 14 wedge-shaped notch 15,16 Dot pattern 17 N mark 18 Dot pattern 19,20 Valley fold 21 Wedge notch 22,23 Dot pattern 24 intermediate sensor paper 25 cylindrical member 26 ferrule 27 Cylindrical member 28, 29 Cylindrical water-permeable sponge 30 Sensor rod 31 Air vent hole 32 N mark 33 Dot pattern 34 shaft sensor paper 35 cylindrical member 36 ferrule 37 cylindrical member 38, 39 cylindrical water-permeable sponge 40 sensor rod 41 Air vent 42 Straight line 43 Dot pattern 44 Tailing

Claims

1. a sensor rod including a cylindrical member, a ferrule connected to a lower end of the cylindrical member, a columnar member extending upward from an upper end of the cylindrical member, and a paper sheet and a water-permeable sponge inserted into the cylindrical member; The cylindrical member is made of a water-permeable body or a water-impermeable body having a large number of through holes, the paper sheet is provided with a dot pattern consisting of one or more dots printed with a water-soluble ink or a fluorescent material; This groundwater flow direction and velocity meter enables the flow direction and velocity of groundwater to be determined based on the tailing of ink or fluorescent substance that dissolves from one or more points and is drawn on the paper sheet by inserting the sensor rod into the ground where groundwater is to be observed and leaving it stationary for a predetermined period of time.

2. The water-permeable sponge is made of a plurality of columnar water-permeable sponges that can be inserted into the tubular member, the paper sheet is made of an intermediate sensor paper sandwiched and held between the plurality of pillar-shaped water-permeable sponges; 2. The groundwater flow direction and velocity meter according to claim 1, which makes it possible to obtain groundwater flow direction and flow velocity two-dimensionally based on the tailing of ink or fluorescent substance drawn on the intermediate sensor paper.

3. the paper sheet comprises a top sensor paper held on the top of the water-permeable sponge and a bottom sensor paper held on the bottom of the water-permeable sponge; 2. A groundwater flow direction and velocity meter as described in claim 1, which makes it possible to determine groundwater flow direction and flow velocity in three dimensions based on the tailing of ink or fluorescent substance drawn on the top sensor paper and the tailing of ink or fluorescent substance drawn on the bottom sensor paper.

4. the sensor rod further includes a columnar body fixed inside the cylindrical member, The cylindrical member and the columnar body have the same central axis, The paper sheet is made of a shaft sensor paper that is held on the side surface of the columnar body, The stem sensor paper is provided with a dot pattern in which a plurality of dots printed with a water-soluble ink or a fluorescent material are arranged around the side surface of the columnar body; the water-permeable sponge is a cylindrical water-permeable sponge that can be inserted into the cylindrical member and arranged around the columnar body; 2. The groundwater flow direction and velocity meter according to claim 1, which makes it possible to obtain groundwater flow direction and flow velocity three-dimensionally based on a plurality of ink or fluorescent substance tailings drawn on the shaft sensor paper.

Images