JP5471624B2 - Method for measuring groundwater flow direction flow velocity and apparatus therefor - Google Patents

Description

  The present invention relates to a method for measuring a groundwater flow direction flow velocity and an apparatus therefor.

  From the viewpoint of land use, ground related to construction work, site condition survey, ground environment conservation, etc., it is required to measure the groundwater flow velocity in addition to the soil permeability coefficient. In order to measure the flow direction and flow velocity of groundwater, a method is usually used in which a hole in the direction perpendicular to the ground is excavated and the flow direction flow velocity measuring device is lowered into the hole, and measurement is performed. Called. As such a single-hole type groundwater flow measuring method, there are methods described in the following patent documents.

  Patent Document 1 is based on the tracer particle method, and has a large-scale configuration including means for causing the tracer particles to flow into the measurement space, means for detecting the three-dimensional position of the suspended matter, transmission means, and the like. Patent Document 2 captures the swinging state of an object to be imaged in groundwater, and requires that fine adjustment is required for the object to be imaged including a floating body, an inclination measuring body, and a locking portion, an imaging device, and the like. As a configuration including

  In the groundwater flow direction flow velocity measuring device described in Patent Document 3, a porous layer is arranged around a cylindrical heating element in a cylindrical probe, and temperature detectors for detecting a temperature distribution in the porous layer are arranged concentrically. The device configuration is considerably large. Moreover, what is described in Patent Document 4 is to perform three-dimensional measurement of the flow direction and flow velocity of groundwater flow using a CCD camera equipped with a parallax optical system in the borehole. What is described is also to obtain the flow direction and flow velocity by performing image processing on an image obtained by a CCD camera housed in a pressure vessel, and the configuration including the imaging device, its support structure, and image processing device is large. It will be something.

  In addition, it is indispensable to provide a power source for the operation of the measuring device in any of the measurements of the groundwater flow direction flow velocity found in Patent Documents 1 to 5, for example, power sources in mountainous areas, remote areas, developing countries, etc. In places where it is difficult to obtain, measurement cannot be performed by operating the measuring device.

JP 2007-256026 A JP-A-2005-345180 JP 11-326359 A JP 2002-257934 A JP-A-9-196958

  In the conventional measurement of the flow velocity in the direction of groundwater flow, a heater or a video camera requires a power source to drive and operate these devices, which makes the device expensive. The tracer method can measure the trend of groundwater flow with considerable accuracy and is currently widely used.However, when the water flow is very slow and the water can move freely, Injecting water into the water also causes problems that make it difficult to measure groundwater flow with high accuracy because the water moves unstable, and this method also requires a power source. Under such circumstances, it has been demanded to measure the groundwater flow direction flow velocity in a form that is simple and inexpensive as a measuring device and does not require the use of a power source as a basic operation.

  The present invention has been made to solve the above-mentioned problems, and the method of measuring the flow velocity in the direction of groundwater according to the present invention prints in a state in which a large number of dot patterns are distributed and arranged with water-soluble ink. The orientation of the measuring device body that holds the paper sheet of a predetermined shape provided with a mark for use in a state of being gripped by a water-permeable sponge from both sides, and descending into the groundwater observation well, and holding it in the groundwater observation well for a predetermined time; Removing and collecting the paper sheet from the measuring apparatus main body after a predetermined time has elapsed, and determining the length and orientation of tailing generated accompanying the dotted pattern printed on the collected paper sheet; And determining the groundwater flow direction flow velocity from the determined length and direction of the tailing.

  The water permeability from both sides in a state where other paper sheets having the same shape and the same size and not printed with a large number of dot-like patterns are stacked so as to cover the surface on which a large number of dot-like patterns of the paper sheet of the predetermined shape are printed. You may make it hold | grip with sponge.

  In addition, the groundwater flow direction flow velocity measuring device according to the present invention prints water-soluble ink in a state in which a large number of dot-like patterns are distributed and arranged on both sides of a paper sheet having a predetermined shape provided with orientation marks using a water-permeable sponge. A measuring device main body in which the gripped object is gripped from both sides with a pair of holding plates and the whole is integrally held, and the measuring device main body is attached to the lower end side of the rod-shaped member and arranged in the groundwater observation well. The rod-shaped member attached to the measuring device main body and rotating with respect to the groundwater observation well while holding the upper end side above the ground surface of the rod-shaped member in a state and fixing it to the pedestal installed on the ground surface A measuring device main body holding and fixing means that can be adjusted and can adjust the orientation of the measuring device main body, and holds the measuring device main body in a groundwater observation well for a predetermined time. After the measuring device main body from the tailing caused in association with a point-like pattern is printed on a paper sheet which is detached recovered length is obtained by the seek the groundwater flow direction the flow rate from the orientation.

  In the measuring apparatus main body, a paper sheet having a predetermined shape which is printed in a state in which a large number of dot patterns are distributed and arranged, and a water-permeable sponge which grips the paper sheet from both sides, and those from both sides. A hole of the same shape and size is formed in the center across each of the pair of holding plates to be gripped, and the paper sheet, the water-permeable sponge, and the holding plate are supported in the same shape and size in the holes provided in them. The rod may be penetrated and held integrally.

  In the measuring apparatus main body, the paper sheet of the predetermined shape is overlapped with other paper sheets that are not printed with a dot pattern in the same shape and size so as to cover the surface on which the dot pattern is printed. It is good also as what is hold | gripped with the water-permeable sponge.

  An orientation magnet is attached to the upper surface of the base that is installed so as to be rotatable and adjustable with respect to the groundwater observation well, which holds and fixes the upper end side above the ground surface of the rod-like member attached with the measuring device main body. In addition, an orientation mark is provided, and the orientation mark provided on the upper end surface of the rod-shaped member and the paper sheet are provided when the measuring device main body is attached to the lower end side of the rod-shaped member. Adjust the direction so that the orientation mark on the paper sheet faces the N direction by aligning the direction with the orientation mark and rotating the base that holds and fixes the rod-shaped member about the axis perpendicular to the ground. You may be able to do it.

  In the measurement of the groundwater flow direction flow velocity according to the present invention, it is basically arranged in a groundwater observation well excavated perpendicularly to the ground in a state where a paper sheet of a predetermined shape printed with a predetermined pattern with water-soluble ink is sandwiched between supports. In addition, it measures the flow velocity in the direction of the groundwater by reading the change in the printed pattern shape due to the groundwater flow, which makes the configuration of the measuring device simple and requires a power source for measurement at the groundwater observation well. And not. This makes it possible to measure in places where it is difficult to obtain power in mountainous areas, remote areas, developing countries, and the like.

(A) is a figure which shows the condition which measures the groundwater direction direction flow velocity by this invention, (b) is the figure which showed the upper part of the fixed base in (a) in the perspective view, (c) is a figure of a base part. It is a figure which shows the state which looked at the part from the downward direction, (d) is sectional drawing which cut | disconnected the base part which adhere | attached and attached the guide with the plane which passes along a central axis. It is a figure which shows the external appearance of a measuring device main body with a perspective view. It is a figure which shows the relationship between the paper sheet | seat of FIG. 2, and the sponge holding this. It is the figure which looked at the paper sheet from the upper part. It is a figure which shows the state seen from the upper direction of a fixed base in order to demonstrate the orientation alignment of a measuring apparatus main body, (a) is a figure which shows the state after aligning an azimuth | direction, (b). It is the figure which looked at the paper sheet after performing measurement operation of groundwater flow direction flow velocity from the upper part. It is a figure which shows the result of the laboratory experiment performed in order to obtain | require the relationship between a flow velocity and the length of tailing.

  Hereinafter, embodiments of the present invention will be described. The groundwater flow direction velocity according to the present invention is basically measured in a groundwater observation well drilled perpendicular to the ground in a state where a paper sheet having a predetermined shape printed with a dye ink or a fluorescent material and having a predetermined pattern is sandwiched between supports. It is arranged to measure the flow velocity in the direction of groundwater flow by reading the change in the printed pattern shape due to the groundwater flow.

[Configuration of measuring device]
FIG. 1A is a diagram showing a situation in which the flow velocity of groundwater flow according to the present invention is measured. As shown in FIG. 1, a cylinder 10 is installed in a groundwater observation well excavated perpendicularly to the ground surface on the ground E. Has been. The depth of the groundwater observation well is about 3-10m. The cylinder 10 is a cylinder formed of a hard plastic or the like, and has an inner diameter of about 70 mm and a large number of small holes 11 that are uniformly formed on the peripheral surface near the observation target depth. The groundwater flows through the small hole 11 so as to pass through the inside of the cylindrical body 10. The cylinder 10 has a circular cross section, and its length can reach the measurement position, and is about 3 to 10 m.

  Reference numeral 1 denotes a measuring apparatus main body sandwiched between paper sheets and placed in the groundwater observation well, which is connected by a connecting member 13 such as a joint attached to the distal end side of the rod-like member 12 and lowered into the groundwater observation well. Held stationary at the position. The fixed holding tool 14 is fixed and held at a portion of the bar-shaped member 12 that protrudes above the ground surface. Before the fixed holding, the bar-shaped member 12 can be adjusted to rotate around an axis perpendicular to the ground. Is. The fixing holder 14 allows the rod-shaped member 12 to be inserted and the height position thereof can be adjusted, and the height position of the rod-shaped member 12 can be adjusted, and the lock member 14a can be locked at that position. The fixing holder 14 is attached to a plate-like fixing base 15 that covers the upper part of the cylindrical body.

  FIG. 1B is a perspective view showing the upper part of the fixed base 15, and a compass magnet 16 is attached to the upper end surface of the fixed base 15, and an orientation alignment mark 17 by an arrow is written or the like. Is provided. FIG. 1 (c) is a view of the portion of the fixing base 15 as viewed from below, but the vertical and horizontal directions of the fixing base 15 can be adjusted so that the rod-like member 12 can be adjusted to rotate around the axis perpendicular to the ground. The width in the direction is larger than the outer periphery of the cylindrical body 10. In addition, a disk-shaped guide 18 for fixing the central axis to the cylindrical body 10 is bonded to the fixing base 15 at the lower part of the fixing base 15. The guides can be aligned with cylinders of various diameters, and a plurality of disks are stacked and bonded so that the diameter gradually decreases from a plastic disk with a large diameter. It can be made to coincide with the inner diameter of 10.

FIG. 1C shows a case where three disks 18a to 18c are sequentially attached to the lower surface of the fixing base 15, and FIG. 1D shows a plane passing through the central axis of the fixing base attached with the guide. It is shown by a sectional view at.
The thickness of each disk is preferably 5 mm to 1 cm. The central part of the fixed base 15 and the guide 18 (discs 18a to 18c in FIGS. 1C and 1D) are hollowed out in a square shape so that the rod-shaped member 12 can penetrate.

  FIG. 2 is a diagram showing the external appearance of the measuring apparatus main body. The measuring apparatus main body 1 shown in FIG. 2 is configured to hold circular paper sheets P1 and P2, and the upper and lower holding plates 2a and 2b have the same shape and size as the paper sheet P. The paper sheets P1 and P2 are sandwiched and held between upper and lower water-permeable sponges 3a and 3b that are circular and have the same shape and size as the paper sheets P1 and P2, and the holding plates 2a and 2b and the sponge 3a. , 3b, and through-holes of the same shape and the same size are formed in the center of the paper sheet P, and the support bar 4 is passed through and held in the through-holes. In FIG. 3, the relationship between the upper and lower sponges 3a and 3b and the paper sheets P1 and P2 inserted and held therebetween is shown.

  The external dimensions of the support bar 4 can be inserted into a rectangular through hole at the center of the holding plates 2a and 2b, sponges 3a and 3b, and the paper sheets P1 and P2, and when inserted, there is substantially no gap. Shall. That is, it is assumed that the paper sheets P1 and P2 and the sponges 3a and 3b sandwiching the paper sheets P1 and P2 are held so as not to move in the horizontal direction even when subjected to the action of the groundwater flow from the lateral direction. The support bar 4 has a length at which the upper and lower ends protrude from the holding plates 2a and 2b.

  As shown in FIG. 2, holding plates 2a and 2b, sponges 3a and 3b, and paper sheets P1 and P2 are arranged, and after the through hole in the center is aligned, the support rod 4 is inserted and fixed by means not shown. The upper and lower holding plates 2 a and 2 b are fixed to the support bar 4. As the fixing means, rubber rings that circulate around the support bar 4 are respectively attached to the upper and lower sides of the holding plates 2a and 2b, or in the lateral direction to the support bar 4 at positions immediately above the holding plate 2a and directly below the holding plate 2b. It is good also as a form which forms the fine hole penetrated in this, and inserts and fixes a pin to these fine holes, or another suitable form.

  The lower holding plate 2b is integrally fixed to the support rod 4 with an adhesive or the like so that the lower sponge 3b, the paper sheet P, the upper sponge 3a, and the upper holding plate 2a overlap in this order. The upper holding plate 2a may be fixed to the support rod 4 by a fixing means. In any case, the sponges 3a and 3b are flexible, and are narrower than the natural interval in which the paper sheets P1 and P2 are sandwiched between the sponges 3a and 3b, that is, the sponges 3a and 3b. It is preferable that the upper and lower holding plates 2a and 2b are set and fixed so as to be lightly compressed, that is, in a state where the paper sheet P is lightly pressed. As a result, the paper sheets P1 and P2 do not float up and down, but are held in a positional relationship that is securely fixed to the measurement apparatus main body 1.

  As materials for the upper and lower holding plates 2a and 2b and the support bar 4, hard plastics such as vinyl chloride resin are used. The sponges 3a and 3b are preferably water-permeable sponges such as melamine foam.

  FIG. 4 is a view of the paper sheets P1 and P2 as viewed from above. The paper sheets P1 and P2 are typically circular in shape, and are made of materials that have an appropriate thickness (about 400 to 500 μm), denseness, and waist strength, similar to drawing paper. Good ones are suitable. A square hole conforming to the outer shape of the support bar 4 is formed at the center, and a large number of dot patterns d are printed at a uniform interval on the circumference of the intermediate position from the center to the periphery for P2. . As a printing method, an ink jet printer using water-soluble black ink is preferably used. In addition, a mark M is attached in advance at one point around the paper sheet. This mark M is for adjusting the direction when setting the measuring device.

  The typical dimensions of the paper sheets P1 and P2 are those having a diameter of about 69 mm, and one side of a central square hole that coincides with the outer shape of the support bar 4 is preferably about 19 mm. These are representative values, but other dimensions may be adopted as appropriate. In addition, although the outer shape of the paper sheets P1 and P2 is circular, other shapes such as polygons may be used. Even in that case, the dot pattern d is printed on the circumference from the measurement surface. Further, the outer shapes of the sponges 3a and 3b and the upper and lower holding plates 2a and 2b are also the same shape and the same size as the outer shapes of the paper sheets P1 and P2.

[Preparation for measurement]
The groundwater flow direction flow velocity measuring apparatus according to the present invention is configured as described above. Next, preparation for measuring the groundwater flow direction flow velocity using the measurement apparatus will be described. First, the required number of paper sheets P1 and P2 having the same quality and the same shape are formed, and for P2, a dot pattern is printed with black ink and arranged at equal intervals on the circumference of the same diameter by an inkjet printer. Keep it.

  Each of the paper sheets P1 and P2 is sandwiched between the sponges 3a and 3b so that the printing surface of P2 is covered with P1, and the upper and lower holding plates 2a as shown in FIG. , 2b and being supported and fixed to the support rod 4, the measurement apparatus main body shown in FIG. 2 is obtained. At this time, as described above, it is preferable that the sponges 3a and 3b are lightly compressed to hold the paper sheets P1 and P2. Further, when the paper sheet P2 is attached to the measuring apparatus main body, for example, a similar mark (not shown) is provided at a position around the upper holding plate so that the position of the orientation alignment mark M provided on the paper sheet P2 can be confirmed. ) Or a line drawn with a sine pen in the vertical direction on the peripheral surfaces of the sponges 3a and 3b, and the mark M on the paper sheet P2 is aligned with these marks or lines. It is preferable to use a configuration in which it is attached as a measuring device main body.

  The portion of the support bar 4 protruding above the measuring apparatus main body is connected by a connecting member 13 attached to the distal end side of the bar-shaped member 12. At that time, a mark for orientation adjustment provided for confirmation from the outside in the measuring apparatus main body (mark on the above-mentioned upper holding plate 2a, side lines of the sponges 3a, 3b, etc.) and the fixing base 15 It is confirmed that the position (direction) with the mark 17 such as an arrow on the upper surface matches.

  With respect to this alignment, when the measuring device body 1 is previously provided with a direction confirmation mark or the like, if the positioning is not performed when the measuring device body 1 is gripped by the connecting member 13 at the tip of the rod-shaped member 12, It is necessary that the member 12 and the measurement apparatus main body 1 can be rotated and adjusted with respect to each other. This is done, for example, by attaching the connecting member 13 to the rod-like member 12 so as to be adjustable.

  If such an adjusting means is not provided, the measuring device main body 1 is not provided with a direction confirmation mark or the like in advance, and the measuring device main body 1 is connected by the connecting member 13 at the tip of the rod-shaped member 12. In this state, a direction alignment mark or the like is attached to the holding plate 2a or the like on the upper side of the measurement apparatus main body 1 so that the direction is aligned with the mark 17 on the upper surface of the fixed base 15. Thereafter, the measuring device main body 1 is once removed, and the portion of the measuring device main body 1 is configured so that the mark M of the paper sheet P2 is aligned with the mark attached to the holding plate 2a or the like. It connects by the connection member 13 of the front-end | tip. The operation of adjusting the direction so that the mark or the like attached to the measuring apparatus main body 1 and the mark 17 on the upper surface of the fixed base 15 coincide with each other is performed by a cylindrical body installed in the groundwater observation well excavated on the ground. This is done before inserting and lowering into the 10.

  FIG. 5 is a diagram showing a state viewed from above the fixed base in order to explain the orientation adjustment of the measuring apparatus main body. (A) shows a state before the orientation is adjusted, and (b) shows a state after the orientation is adjusted. Yes. After aligning the direction such that the mark or the like attached to the measuring apparatus main body 1 and the mark 17 on the upper surface of the fixing base 15 coincide with each other, the rod-shaped member 12 is locked by the lock member 14a and kept at the position before insertion. At this time, as shown to (a), generally the label | marker 17 and N of a compass are not in agreement. The fixing table 15 is rotated about the axis perpendicular to the ground so that the mark 17 on the upper surface of the fixing table 15 and the azimuth magnet N are aligned, and when they are aligned as shown in (b), the locking member 14a of the fixing holder 14 is obtained. As shown in FIG. 1, the measuring apparatus main body 1 is lowered to the measurement target position in the cylinder 10 installed in the groundwater observation well excavated on the ground. The rod-shaped member is kept in that position, and 14a is locked. This prepares for the measurement of the groundwater flow direction flow velocity.

[Measurement of groundwater flow velocity]
Measurement is started when the paper sheets P1 and P2 are attached to the measuring apparatus main body 1 and are aligned as shown in FIG. The measurement apparatus main body 1 receives the groundwater flow, and the paper sheets P1 and P2 are subjected to the action of the groundwater flow while being held by the water-permeable sponges 2a and 2b. The time for placing the paper sheets P1 and P2 in the groundwater flow is set to a predetermined value, and after the predetermined time has elapsed for each paper sheet P1 and P2, the fixing of the measuring device main body is released, the paper sheet P2 is removed, Leave to dry.

  After drying, the paper sheet P2 is generally as shown in FIG. Each dot pattern d applied to the paper sheet P by printing has an ink tailing d 'as shown in FIG. The direction and length of the tailing d ′ have a generally uniform tendency and are considered to correspond to the direction and speed of the groundwater flow. Therefore, the flow direction and flow velocity of the groundwater flow are specified from the direction and length of the tailing d 'for the paper sheet P obtained by drying after being immersed in the groundwater flow. Specifically, it is preferable to use a method of scanning the paper sheet P after it has been dried, taking it into a computer as image data, and specifying the length of the longest tailing on the downstream side by image analysis.

  When acquiring the image data about the paper sheet P2 removed from the measuring apparatus main body, it may be performed using a digital camera. In this case, it is not always necessary to sufficiently dry the paper sheet P2, and the paper sheet P2 can be wet. In addition, when measuring the flow direction and flow velocity, for a single groundwater observation well, a plurality of paper sheets P1 and P2 of the same condition are exchanged at one depth position, a plurality of measurements are performed, and the results are aggregated. It is better to take the average and obtain the flow direction and flow velocity.

  FIG. 7 is a diagram showing the results of a laboratory experiment conducted to determine the relationship between the flow velocity and the tailing length. The paper sheet used is a paper sheet printed using an inkjet printer Pixus 950i (manufactured by Canon Inc.). In FIG. 7, the vertical axis is a value obtained by dividing the trajectory length (tailing length) by the measurement time. From the distribution of measured values indicating the relationship with the Darcy velocity on the horizontal axis, a test straight line is shown between these quantities. Corresponding relationships are seen. The coefficient of determination of the test line is 0.9396, which is high. In the figure, the y-intercept indicates the diffusion rate in the no-flow state.

In the above-described measuring device main body of the groundwater flow direction flow velocity measuring device, as shown in FIG. 2, a configuration in which a pair P of paper sheets P1 and P2 is sandwiched between a pair of sponges 3a and 3b is shown. For example, three sponges 3a, 3b, 3c having the same shape are used, a pair of two paper sheets is sandwiched between the sponges 3a, 3b, and another two sheets 1 between the sponges 3b, 3c 1 It is good also as a form hold | maintained integrally by holding | maintenance board 2a, 2b and the support bar 4 which pinched the pair of paper sheet set. In such a configuration, two paper sheets can be used to perform measurement twice.
In the above description, the case where two pairs of paper sheets on which a large number of dot patterns are printed and paper sheets on which printing is not performed is used as a set. The flow direction flow velocity may be measured as a form in which a sheet of paper printed with a dot pattern is sandwiched between water-permeable sponges by using an appropriate one.

  In addition, the measurement device main body of the above-described groundwater flow direction flow velocity measurement device has a paper sheet having a predetermined shape on which a plurality of dot patterns are distributed and arranged, and provided with orientation marks, and water permeability that holds the paper sheet from both sides. A hole of the same shape and size is formed in the center over each of the porous sponge and a pair of holding plates that hold them from both sides, and the paper sheet, the water-permeable sponge, and the holding plate are formed in the holes provided in them. Although the cross section of the same shape and the same size of the support rod is shown as being held integrally, the same shape and size paper sheet, water permeable sponge, holding plate are integrally held at the bottom of the rod-shaped member As long as it is attached, it can be in other forms, for example, without forming a hole in the center of each of the same shape and same size paper sheet, water permeable sponge, and holding plate. Body to closely accommodated in a basket-shaped member surrounding, it may form such as attached to the lower portion of the rod.

  When the orientation of the measuring device main body is adjusted, the orientation is adjusted before the measuring device main body 1 is lowered into the groundwater observation well, and then the measuring device main body 1 is lowered to the measurement target position in the groundwater observation well. However, in the present invention, it is only necessary that the measuring apparatus main body 1 can be pivotally adjusted with respect to the groundwater observation well for orientation, and other forms are possible.

  For example, in order to be able to adjust the rotation of the rod-shaped member 12 with respect to the groundwater observation well, a hole through which the rod-shaped member 12 is inserted is formed as the fixed holder 14 that holds the rod-shaped member 12 to which the measuring apparatus main body 1 is attached. The outer peripheral surface of the inner member is formed into a columnar shape, and this is configured to have a double structure in which the inner member can be rotated within the columnar hole of the outer member. Thereby, the rod-shaped member 12 to which the measuring apparatus main body is attached can be adjusted to rotate with respect to a fixed base that is fixedly installed in the groundwater observation well. In the case of this configuration, the alignment is performed after the measuring device main body is lowered into the groundwater observation well.

  In the measurement of the flow velocity of the groundwater flow according to the present invention, the configuration of the measuring device is simple, the cost can be reduced, and no power source is required for the operation of the measuring device at the time of measurement. Can also be measured.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus main body 2a, 2b Holding | maintenance board 3a, 3b Sponge 4 Supporting rod 10 Cylindrical body 11 Small hole 12 Rod-shaped member 13 Connecting member 14 Fixed holding tool 14a Locking member 15 Fixing base 16 Directional magnet 17 Marking 18 (ac) guide E Ground M Orientation mark P1 Paper sheet (white paper)
P2 paper sheet (printing)
P Set of paper sheets consisting of P1 and P2 d Point pattern d 'Ink tailing

Claims (6)

Orientation of the main body of the measuring device that prints in a state in which a large number of dot patterns are distributed and arranged with water-soluble ink and holds a paper sheet of a predetermined shape provided with orientation marks from both sides with a water-permeable sponge And descent into the groundwater observation well and hold it in the groundwater observation well for a predetermined time,
Removing and collecting the paper sheet from the measuring device body after a predetermined time has elapsed;
Determining the length and orientation of the tailing that accompanies the dot pattern printed on the collected paper sheet;
Obtaining the groundwater flow direction flow velocity from the length and direction of the obtained tailing;
A method for measuring the direction velocity of groundwater flow characterized by comprising:   The water permeability from both sides in a state where other paper sheets having the same shape and the same size and not printed with a large number of dot-like patterns are stacked so as to cover the surface on which a large number of dot-like patterns of the paper sheet of the predetermined shape are printed. 2. The method for measuring the flow velocity in the direction of groundwater flow according to claim 1, wherein the method is configured to grip with a sponge. A paper sheet with a predetermined shape that is printed with water-soluble ink in a distributed pattern, and is gripped on both sides with a water-permeable sponge. And a measuring device main body integrally holding the whole,
A base that is installed on the ground surface while holding the upper end side above the ground surface of the rod-shaped member in a state where the measuring device main body is attached to the lower end side of the rod-shaped member and disposed in the groundwater observation well. A measuring apparatus body holding and fixing means that can be adjusted to rotate with respect to the groundwater observation well and the rod-like member to which the measuring apparatus body is attached is capable of adjusting the orientation of the measuring apparatus body,
The length and direction of tailing that accompanies the dotted pattern printed on the paper sheet that was removed from the main body of the measuring apparatus after being retained for a predetermined time in the groundwater observation well. A groundwater flow direction flow velocity measuring device characterized in that the groundwater flow direction flow velocity is obtained from the groundwater flow direction.   In the measuring apparatus main body, a paper sheet having a predetermined shape which is printed in a state in which a large number of dot patterns are distributed and arranged, and a water-permeable sponge which grips the paper sheet from both sides, and those from both sides. A hole of the same shape and size is formed in the center across each of the pair of holding plates to be gripped, and the paper sheet, the water-permeable sponge, and the holding plate are supported in the same shape and size in the holes provided in them. The groundwater flow direction flow velocity measuring device according to claim 3, wherein the rod penetrates the rod and is integrally held.   In the measuring apparatus main body, the paper sheet of the predetermined shape is overlapped with other paper sheets that are not printed with a dot pattern in the same shape and size so as to cover the surface on which the dot pattern is printed. The groundwater flow direction flow velocity measuring device according to claim 3, wherein the groundwater flow direction flow velocity measuring device is held by a water-permeable sponge. An orientation magnet is attached to the upper surface of the base that is installed so as to be rotatable and adjustable with respect to the groundwater observation well, which holds and fixes the upper end side above the ground surface of the rod-like member attached with the measuring device main body. In addition, an orientation mark is provided, and the orientation mark provided on the upper end surface of the rod-shaped member and the paper sheet are provided when the measuring device main body is attached to the lower end side of the rod-shaped member. Adjust the direction so that the orientation mark on the paper sheet faces the N direction by aligning the direction with the orientation mark and rotating the base that holds and fixes the rod-shaped member about the axis perpendicular to the ground. The groundwater flow direction flow velocity measuring device according to any one of claims 3 to 5, wherein the device is capable of being made.

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