Water level adjustment device and water storage device

Abstract

To provide a water level adjustment device that can appropriately manage the water level in a rice field even when the height of the rice field changes.SOLUTION: Provided is a water level adjustment device 10 installed in a catch basin 100 of a rice field, the catch basin having a bottom wall 101 and a pair of side walls 103, 104 erected facing each other from the bottom wall 101. The water level adjustment device comprises: a plate-shaped reference sheathing board 20 that can be installed between the pair of side walls 103 and 104 with the front facing the paddy field side and is provided with a hole penetrating in the front-rear direction; and a movable member 40 having a flow path with an inlet located on the front side and an outlet located on the rear side and assembled to the reference sheathing board so that the flow path passes through the hole, the movable member 40 being assembled to the reference sheathing board 20 so that the position of the lower end of the flow path can be changed. The hole is a long hole extending in the vertical direction and the movable member 40 is slidable along the direction in which the long hole extends.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water level adjustment device and a water storage device to be installed at the outlet of a rice paddy field. [Background technology]

[0002] Traditionally, paddy field water channels have been equipped with a water outlet manhole, and when storing water in the paddy field, a wooden board is attached to the manhole to prevent water from flowing out, and when draining the paddy field, the wooden board attached to the manhole is removed. When attaching wooden boards to the manhole in this way, multiple wooden boards of different heights must be prepared to adjust the water level in the paddy field, and fine adjustment of the water level is difficult.

[0003] A water level adjustment device that solves these problems is described in Patent Document 1. In the water level adjustment device described in Patent Document 1, when the water level in the paddy field is to be increased, the water level adjustment pipe is raised to raise the position of the water intake, and when the water level in the paddy field is to be decreased, the water level adjustment pipe is pushed down to lower the position of the water intake. In addition, when draining water from the paddy field, the water level adjustment pipe is removed, allowing the water level to be lower than when the water level adjustment pipe is used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 3136199 Summary of the Invention [Problem to be solved by the invention]

[0005] The water level adjustment device described in Patent Document 1 was unable to adequately adjust the water level when the height of the rice paddy surface changed. That is, when the height of the rice paddy surface decreased, the height from the rice paddy surface to the water intake may have been higher than the required water level, even if the water intake of the water level adjustment pipe had been set to its lowest position. Also, when the height of the rice paddy surface increased, the height from the rice paddy surface to the water intake may have been lower than the required water level, even if the water intake of the water level adjustment pipe had been set to its highest position.

[0006] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a water level adjustment device that can appropriately manage the water level in a paddy field even when the height of the paddy field surface changes, and a water storage device that uses this water level adjustment device. [Means for solving the problem]

[0007] The first configuration is a water level adjustment device installed in a rice paddy outfall manhole having a bottom wall and a pair of side walls erected opposite the bottom wall, and comprising: a plate-shaped reference weir plate that can be installed between the pair of side walls with its front facing the rice paddy and has holes that penetrate in the front-to-back direction; and a movable member that has a flow path with an inlet located at the front and an outlet located at the rear, and is assembled to the reference weir plate so that the flow path passes through the holes, and the movable member is assembled to the reference weir plate so that the position of the lower end of the flow path can be changed.

[0008] In the first configuration, when the height of the rice paddy surface changes, the lower end position of the movable member's flow path can be aligned with the rice paddy surface, and the water level can be appropriately controlled from the rice paddy surface even when the height of the rice paddy surface changes.

[0009] In the second configuration, in addition to the first configuration, the hole is an elongated hole extending in the vertical direction, and the movable member is slidable along the direction in which the elongated hole extends.

[0010] In the second configuration, the position of the lower end of the flow channel can be finely adjusted, so that the water level in the rice paddy can be more suitably adjusted.

[0011] In the third configuration, in addition to the second configuration, the reference dam plate has a first assembly hole which is a hole extending around the long hole in the extension direction of the long hole, and the movable member has a flange portion which covers a part of the long hole and the first assembly hole when attached to the reference dam plate, and the flange portion has a second assembly hole through which a screw which has passed through the first assembly hole can pass.

[0012] In the third configuration, the flange portion covers the first assembly hole, thereby preventing water from leaking out from the first assembly hole. Also, because the movable member can be assembled with screws, it is easy to switch between the permanently assembled state and the temporary assembled state, and by sliding the movable member in the temporary assembled state, it is easy to fine-tune the position of the movable member.

[0013] A fourth configuration is the same as any one of the first to third configurations, in which the reference dam board further includes a drain opening penetrating in the front-rear direction below the hole, and the drain opening is closable.

[0014] In the fourth configuration, by opening the blocked drain outlet, the water level can be set lower than the water level that can be adjusted by the movable member.

[0015] The fifth configuration is, in addition to any of the first to fourth configurations, such that the flow path on the paddy field side of the reference dam plate is formed inside a cylindrical body that is bent along the way, and the height of the inlet can be changed by rotating it around an axis on the reference dam plate side of the bent point.

[0016] In the fifth configuration, the water level in the rice paddy can also be changed by changing the height of the inlet of the movable member.

[0017] A sixth configuration is a water storage device, comprising the water level adjustment device of any one of the first to fifth configurations, and a lid that can block the flow path or limit the flow rate.

[0018] In the sixth configuration, it is possible to stop or restrict the outflow of water from the flow path, so that in cases such as when heavy rain makes it necessary to use the rice paddy as a water storage tank, it is possible to maintain a water level higher than the water level that can be adjusted by the water level adjustment device.

[0019] In the seventh configuration, in addition to the sixth configuration, the reference dam plate further includes an overflow hole above the hole, which is a hole that penetrates in the front-to-rear direction, and the width of the overflow hole increases as it goes upward.

[0020] In the seventh configuration, the higher the water level, the greater the increase in the amount of water flowing out from the overflow hole. Therefore, when the water flow is stopped, the amount of water flowing into the rice paddy increases, and as the water level rises accordingly, drainage can be carried out more quickly. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 10 is a perspective view showing a water level adjustment device attached to the outlet manhole. [Figure 2] This is an oblique view of a drop-mouth box. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 2 is a perspective view of each part that constitutes the movable member. [Figure 10] FIG. [Figure 11] FIG. 10 is a side view showing a state in which the movable member is attached to the adjustment plate. [Figure 12] This shows the water level adjustment device in use. [Figure 13] 10 is a diagram showing the positional relationship between the height of the rice field surface and the height of the adjustment plate and movable member. FIG. [Figure 14] 14 is a diagram showing the positional relationship between the height of the adjustment plate and the movable member when the height of the rice field surface is higher than that shown in FIG. 13. [Figure 15] 10A and 10B are diagrams showing a state in which the movable member is tilted to adjust the water level. [Figure 16] FIG. 10 is a diagram showing a state in which water is drained from a drain outlet. [Figure 17] FIG. 10 is a diagram showing a state in which the water level adjustment device is used as a water storage device. DETAILED DESCRIPTION OF THE INVENTION

[0022] As shown in Figure 1, the water level adjustment device 10 according to the embodiment is attached to an outlet manhole 100 provided in a water conduit in a paddy field. In the following description, the top-bottom direction is the up-down direction, the paddy field side of the water conduit is the forward direction, and the width direction of the water conduit is the left-right direction. Furthermore, each component is made of hard resin unless otherwise specified.

[0023] First, the structure of the water-drop box 100 will be described with reference to Figure 2. The water-drop box 100 is integrally cast from concrete. The water-drop box 100 has a bottom plate 101, which is a rectangular flat plate extending in the front-to-rear direction. A bottom groove 102 extending in the left-to-right direction parallel to the front and rear ends is formed slightly toward the rear end of the bottom plate 101 in the front-to-rear direction. Flat side walls 103, 104, which stand upward and have a substantially uniform thickness in the left-to-right direction, are provided opposite the left and right ends of the bottom plate 101. The side walls 103, 104 have the same shape, with the front end lower than the rear end, and their height gradually decreases from the rear end to the front end. Side wall grooves 105, 106, which are grooves extending upward, are provided on the inner surfaces of the side walls 103, 104 at the same front-to-rear position as the bottom groove 102.

[0024] A flat rear wall 107 that stands upward and has a uniform thickness in the front-to-rear direction is provided at the rear ends of the bottom plate 101 and the side walls 103, 104. A circular discharge hole 108 that penetrates in the front-to-rear direction is provided near the lower end of this rear wall 107. The center of this discharge hole 108 is approximately aligned with the center of the rear wall in the left-to-right direction, and the diameter of the discharge hole 108 is approximately half the width of the rear wall 107.

[0025] The water level adjustment device 10 installed in the above-described outfall basin 100 includes a plate-shaped reference dam plate 20, and an adjustment plate 30 and a movable member 40 assembled to the reference dam plate 20, as shown in FIGS.

[0026] As shown in Figure 7, the standard dam plate 20 is a rectangular flat plate extending upward. The left-right width of the standard dam plate 20 is greater than the distance between the side walls 103, 104 of the inlet manhole 100 and is approximately equal to the distance between the side wall grooves 105, 106 provided in the side walls 103, 104. The vertical height of the standard dam plate 20 is higher than the height of the positions where the side wall grooves 105, 106 are provided in the side walls 103, 104 and slightly lower than the height of the rear wall 107.

[0027] An elongated hole 21 penetrating in the front-to-rear direction is provided at a position slightly to the left of the center of this reference dam board 20. When viewed from the front, this elongated hole 21 has an oval shape extending in the vertical direction, with the outer diameter defined by a pair of parallel straight lines extending in the vertical direction and a pair of semicircular arcs connecting the upper ends of the straight lines and the lower ends of the straight lines.

[0028] A first assembly hole 22, which is a hole that penetrates in the front-to-rear direction and extends in the up-down direction, is provided at each of the upper left, upper right, lower left, and lower right of this elongated hole 21. The upper left first assembly hole 22 and the upper right first assembly hole 22 are provided in parallel and are positioned at the same vertical position. Similarly, the lower left first assembly hole 22 and the lower right first assembly hole 22 are provided in parallel and are positioned at the same vertical position. Furthermore, the distances from the left end of the reference dam panel 20 between the upper left first assembly hole 22 and the lower left first assembly hole 22, and the distances from the right end of the reference dam panel 20 between the upper right first assembly hole 22 and the lower right first assembly hole 22 are all equal.

[0029] An overflow hole 23, which is a hole that penetrates in the front-to-rear direction, is provided at a position above the long hole 21 in the standard dam plate 20. The outer shape of this overflow hole 23 is a roughly rounded isosceles triangle facing downward, with the apex angle located on the lower side and base angles located on the left and right ends of the upper side, and the base angles are arc-shaped.

[0030] A drain outlet 24, which is a circular hole that penetrates in the front-to-rear direction, is provided at a position near the lower end below the long hole 21 of the standard dam plate 20. A roughly disk-shaped cap 25 that can close the drain outlet 24 can be attached to this drain outlet 24, and by attaching and detaching the cap 25, the drain outlet 24 can be switched between an open state and a closed state.

[0031] Next, the shapes of the adjusting plate 30 and the movable member 40 to be assembled to the reference shear panel 20 will be described. As shown in FIG. 8 , the adjusting plate 30 is a square flat plate with a substantially uniform thickness. A mounting hole 31, which is a circular hole penetrating in the front-to-rear direction, is provided at a position slightly left of the center of the adjusting plate 30. The diameter of this mounting hole 31 is substantially equal to the length of the minor axis of the long hole 21 of the reference shear panel 20. Second assembly holes 32, which are circular holes penetrating in the front-to-rear direction, are provided at the upper left, upper right, lower left, and lower right of the mounting hole 31. The vertical spacing between the second assembly holes 32 is substantially equal to the vertical spacing between the first assembly holes 22 of the reference shear panel 20, and the left-to-right spacing between the second assembly holes 32 is substantially equal to the left-to-right spacing between the first assembly holes 22 of the reference shear panel 20. Furthermore, the distance between the attachment hole 31 and the second assembly hole 32 in the left-right direction is approximately equal to the distance between the elongated hole 21 of the standard dam board 20 and the first assembly hole 22 in the left-right direction.

[0032] Because the adjusting plate 30 is formed as described above, when the reference dam plate 20 and the adjusting plate 30 are superimposed, the positions of the first assembly holes 22 and the second assembly holes 32 can be aligned. Furthermore, when the positions of the first assembly holes 22 and the second assembly holes 32 are aligned, the center of the elongated hole 21 in the left-right direction and the center of the mounting hole 31 are aligned.

[0033] A movable member 40 is attached to the mounting hole 31 of the adjusting plate 30. As shown in FIGS. 9 and 10 , the movable member 40 is composed of an elbow pipe 41, a cylindrical pipe 42, and a packing 43. The elbow pipe 41 is a well-known hollow pipe with a bent pipe axis, and openings at both ends are displaced by 90 degrees. The height from the bent point of the elbow pipe 41 to the opening is slightly shorter than the length from the left end of the elongated hole 21 in the reference dam plate 20 to the right end of the reference dam plate 20. The cylindrical pipe 42 connected to one opening of the elbow pipe 41 has an outer diameter approximately equal to the inner diameter of the elbow pipe 41, and an annular enlarged diameter portion 42a is formed on the outer peripheral surface on the side opposite to the side connected to the elbow pipe 41. The outer diameter of the enlarged diameter portion 42a is approximately equal to the inner diameter of the mounting hole 31. By connecting the cylindrical pipe 42 to the elbow pipe 41, an internal flow path is formed that extends from the opening on the side of the elbow pipe 41 that is not connected to the cylindrical pipe 42 to the opening on the side where the expanded diameter portion 42a of the cylindrical pipe 42 is formed.

[0034] The packing 43 is annular and made of elastic resin such as rubber. The inner diameter of the packing 43 is approximately equal to the outer diameter of the cylindrical tube 42, and the outer diameter is larger than the outer diameter of the expanded diameter portion 42a of the cylindrical tube 42. A groove 43a is formed around the entire circumference approximately midway along the length, with the width of the groove 43a being approximately equal to the thickness of the adjusting plate 30 and the outer diameter of the portion where the groove 43a is provided being approximately equal to the inner diameter of the mounting hole 31 of the adjusting plate 30. Resin washers (not shown) are provided at the front and rear ends of the groove 43a to improve sliding when the groove 43a is fitted into the mounting hole 31 of the adjusting plate 30.

[0035] A packing 43 is fitted onto the cylindrical tube 42 described above from the side opposite to the side where the enlarged diameter portion 42a is provided (the front side), and then the side opposite to the side where the enlarged diameter portion 42a is provided (the front side) is inserted into one opening of the elbow tube 41, thereby forming the movable member 40. The packing 43 of the movable member 40 is then inserted into the mounting hole 31 of the adjusting plate 30, and the inner circumferential surface of the mounting hole 31 fits onto the groove 43a of the packing 43, thereby attaching the movable member 40 to the adjusting plate 30. At this time, as shown in FIG. 11 , a portion of the rear end side of the packing 43 and the enlarged diameter portion 42a of the cylindrical tube 42 protrude from the rear side of the adjusting plate 30. When the adjusting plate 30 and the movable member 40 are combined in this manner, the adjusting plate 30 is a plate-shaped member that is provided so as to widen from the rear end side of the movable member 40, and therefore can be referred to as a flange portion.

[0036] As shown in FIGS. 3 to 6 , the adjusting plate 30 described above is attached to the standard dam plate 20 using screws 51 and nuts 52. Specifically, first, the enlarged diameter portion 42a protruding from the rear side of the adjusting plate 30 is inserted into the elongated hole 21 from the front side. At this time, the packing 43 located on the front side of the enlarged diameter portion 42a comes into close contact with the periphery of the elongated hole 21. When the adjusting plate 30 is attached to the standard dam plate 20 in this manner, the first assembly holes 21 and the second assembly holes 31 overlap, and therefore the screws 51 are inserted from the rear side to the front side, i.e., from the first assembly hole 21 side to the second assembly hole 31 side. Then, the screws 51 are threaded into the nuts 52 located on the front side of the adjusting plate 30, thereby completing the attachment of the adjusting plate 30 to the standard dam plate 20. By attaching the adjusting plate 30 to the reference dam plate 20 in this manner, the flow path inside the movable member 40 has the inlet located at the front side and the outlet located at the rear side.

[0037] The water level adjustment device 10, which is composed of a reference weir plate 20 and an adjustment plate 30, is attached by being inserted into the outlet basin 100 from above, as shown in Figure 1. Specifically, the water level adjustment device 10 is inserted into side wall grooves 105, 106 formed in the side walls 103, 104, and the lower end of the water level adjustment device 10 fits into the bottom groove 102 formed in the bottom plate 101, thereby attaching the device.

[0038] When the water level adjustment device 10 described above is attached to the outlet manhole 100 and used, as shown in Figure 12, paddy field soil 200 will seep into the outlet manhole 100, and approximately the lower half of the standard dam plate 20 will be covered with the soil 200. At this time, depending on the height of the soil 200, the drainage outlet 24 of the standard dam plate 20 will be completely covered with the soil 200. Note that the portion of the standard dam plate 20 below the long hole 21 can be called an earth retaining portion because it prevents the inflow of soil 200, and the drainage outlet 24 can be said to be formed in that earth retaining portion.

[0039] The water level adjustment device 10 can change the height of the inlet and outlet of the movable member 40 by changing the height at which the adjustment plate 30 is attached to the reference dam plate 20. Specifically, the screws 51 are loosened to create a temporary assembly state, and the adjustment plate 30 is slid up and down so that the screws 51 move along the first assembly holes 22 of the reference dam plate 20. At this time, the movable member 40 inserted into the elongated holes 21 of the reference dam plate 20 also slides up and down along the elongated holes 21, changing the height of the adjustment plate 30 and the movable member 40. Once the height of the adjustment plate 30 and the movable member 40 has been determined, the screws 51 are tightened to create a permanent assembly state, thereby completing the assembly of the adjustment plate 30 and the movable member 40.

[0040] When adjusting the height of the adjusting plate 30 and the movable member 40, the position of the lower end of the movable member 40 is adjusted to approximately coincide with the height of the surface of the paddy field (paddy field surface). This ensures a constant height from the paddy field surface to the opening of the upper end of the movable member 40, thereby maintaining a constant water level from the paddy field surface when the paddy field is flooded. For example, if the height of the lower end of the movable member 40 is at position A as shown in FIG. 13 and the paddy field surface is at position B, which is higher than position A, the adjusting plate 30 can be slid upward as shown in FIG. 14 to set the height of the lower end of the movable member 40 to position B. Changing the height of the lower end of the movable member 40 in this manner also changes the position of the lower end of the internal flow path of the movable member 40. In this embodiment, the length of the first assembly hole 21 and the height of the elbow pipe 41 are determined so that the upper end of the movable member 40 does not reach the height of the lower end of the overflow hole 23, even when the adjusting plate 30 and the movable member 40 are at their highest positions.

[0041] Furthermore, when lowering the water level while maintaining the position of the lower end of the movable member 40, as shown in Figure 15, the movable member 40 is rotated around the center of the mounting hole 31 as viewed from the front. This lowers the inflow height of the upper opening of the movable member 40, allowing the water level in the paddy field to be lowered. In this case, the height from the bent point of the elbow pipe 41 to the opening is slightly shorter than the length from the left end of the elongated hole 21 in the standard weir plate 20 to the right end of the standard weir plate 20, so even if the movable member 40 is rotated clockwise as viewed from the front, it will not come into contact with the right side wall 104 of the outlet manhole 100. Therefore, the movable member 40 can be rotated clockwise by 90 degrees.

[0042] When the water level adjustment device 10 according to this embodiment is attached to the outlet manhole and it is necessary to drain water from the paddy field, the cap 25 is removed to open the drain outlet 24. When performing this operation, if the drain outlet 24 is covered with soil 200 as shown in Fig. 12, the soil 200 in the center is removed to expose the drain outlet 24 as shown in Fig. 16, and the cap 25 is then removed. This makes it possible to drain water at a position lower than the position where the movable member 40 is attached.

[0043] The water level adjustment device 10 according to this embodiment can also be used as a water storage device or a water stop device by closing the internal flow path of the movable member 40 with a lid 60, as shown in FIG. 17 . Specifically, the disk-shaped lid 60 is attached to and closes the opening at the upper end of the movable member 40 (the opening on the side not connected to the elbow pipe 41). This prevents water from flowing out of the movable member 40, and allows water to be stored up to a level higher than the water level that can be adjusted by the water level adjustment device 10. When the water level rises above the upper end of the movable member 40 and reaches the overflow hole 23, water is drained from the overflow hole 23. As described above, the shape of the overflow hole 23 is an isosceles triangle with the apex angle located on the lower side, and therefore the width of the flow path increases toward the upper side. Therefore, the higher the water level, the greater the increase in the amount of water drained.

[0044] 17 completely closes the opening of the movable member 40, it may also be possible to close only a portion of it to limit the flow rate. In this case, if the water level rises above the upper end of the movable member 40, water will be drained from the movable member 40. However, if the water level cannot keep up with the rising water level and the water level exceeds the upper end of the movable member 40 and reaches the overflow hole 23, water will be drained from the overflow hole 23. In addition, the overflow hole 23 can be used as a handle when removing or carrying the water level adjustment device 10.

[0045] With the above configuration, the water level adjustment device 10 according to this embodiment and the water storage device using the water level adjustment device 10 have the following advantages.

[0046] When the height of the rice field surface changes, the lower end position of the internal flow path of the movable member 40 can be aligned with the rice field surface, and the water level can be appropriately controlled from the rice field surface even when the height of the rice field surface changes.

[0047] The height of the movable member 40 can be changed by sliding the adjustment plate 30 up and down, which allows for fine adjustment of the lower end position of the internal flow path of the movable member 40, making it possible to more appropriately adjust the water level in the rice paddy.

[0048] Since the adjustment plate 30 covers the first assembly hole 22, the outflow of water from the first assembly hole 22 can be suppressed.

[0049] The adjustment plate 30 to which the movable member 40 is attached can be assembled using the screws 51, so that the height can be adjusted in a temporary assembly state and then the actual assembly state can be carried out once the desired height is achieved, making installation easier.

[0050] By opening the drain outlet 25 provided near the lower end of the standard dam plate 20, the water level can be set lower than the water level that can be adjusted by the movable member 40. In addition, when opening the drain outlet 25, it is only necessary to remove the soil 200 near the center that covers the drain outlet 25, making the draining operation easier.

[0051] The height of the inlet can be changed by rotating the movable member 40, so the water level in the paddy field can be adjusted while maintaining the lower end position of the internal flow path of the movable member 40.

[0052] The center of the long hole 21 is positioned off-center in the left-right direction of the standard weir board 20, so even when the movable member 40 is rotated, it is less likely to come into contact with the side wall 104 of the outlet manhole 100. This allows the movable member 40 to rotate at a larger angle, thereby increasing the range of water level adjustment function achieved by rotating the movable member 40.

[0053] By attaching the lid 60 to the opening of the movable member 40, it is possible to stop or limit the outflow of water from the movable member 40, so that in cases such as when heavy rain makes it necessary to use the rice paddy as a water storage tank, it is possible to maintain a water level higher than the water level that can be adjusted by the water level adjustment device 10.

[0054] The width of the overflow hole 23 increases as it moves upward, and the higher the water level, the greater the increase in the amount of drainage. Therefore, if the amount of water flowing into the rice paddy increases when the water supply is stopped and the water level rises, drainage can be carried out more quickly.

[0055] <Modification> In the embodiment, the reference dam plate 20 is provided with an elongated hole 21, and the flow path of the movable member 40 passes through the elongated hole 21. However, the reference dam plate 20 may be provided with a plurality of holes at different vertical positions, and the flow path of the movable member 40 may be selected to pass through any of the holes. This also makes it possible to change the position of the lower end of the flow path of the movable member 40. In this case, the first assembly hole 22 may be a hole extending in the vertical direction, or multiple assembly holes may be provided according to the attachment position of the movable member 40.

[0056] In the embodiment, the height of the inlet is changed by rotating the movable member 40, but the height of the inlet may also be changed by using the movable member 40 as a double cylinder with the inner cylinder extending upward. Also, if the movable member 40 is a double cylinder that can also be rotated, fine adjustment of the water level can be made more easily.

[0057] The movable member 40 is composed of an elbow pipe 41 and a cylindrical pipe 42, and the interior thereof serves as a drainage flow path, but the configuration of the pipes that make up the movable member 40 is not limited to that in the embodiment and can be modified in various ways. That is, it is sufficient if the pipes form a flow path with an inlet located at the front and an outlet located at the rear.

[0058] In the embodiment, the shape of the overflow hole 23 is an isosceles triangle with an apex angle at the bottom, but other shapes can be selected as long as the flow path width increases upward. Also, multiple circular or other overflow holes may be provided, with the number of overflow holes arranged horizontally increasing upward, which is equivalent to the flow path width increasing upward.

[0059] In the embodiment, the overflow hole 23 can also be used as a handle, but a handle separate from the overflow hole 23 may be provided at the upper end of the reference dam board 20.

[0060] In the embodiment, the adjustment plate 30 is attached to the reference dam plate 20 using the screw 51, but the position may be maintained only by friction between the adjustment plate 30 and the reference dam plate 20 or friction between the movable member 40 and the reference dam plate 20, or various other assembly methods may be used. [Explanation of symbols]

[0061] Water level adjustment device...10, standard weir plate...20, elongated hole...21, first assembly hole...22, overflow hole 23, drain outlet...24, adjustment plate...30, mounting hole...31, second assembly hole...32, movable member...40, elbow pipe...41, cylindrical pipe...42, packing...43, screw...51, drop mouth box...100

Claims

1. A water level adjustment device installed in a rice paddy outlet basin having a bottom wall and a pair of side walls erected opposite to each other from the bottom wall, a plate-shaped reference dam plate that can be installed between the pair of side walls with its front surface facing the paddy field side and has a hole penetrating in the front-to-rear direction; a movable member having a flow path with an inlet located at the front side and an outlet located at the rear side, the movable member being inserted into the hole from the front side so that the flow path passes through the hole and assembled to the reference dam plate; A water level adjustment device, wherein the movable member is attached to the reference weir plate so as to be able to change the position of the lower end of the flow path.

2. The hole is a long hole extending in the vertical direction, The water level adjustment device according to claim 1 , wherein the movable member is slidable along the extending direction of the elongated hole.

3. A water level adjustment device installed in a rice paddy outlet basin having a bottom wall and a pair of side walls erected opposite to each other from the bottom wall, a plate-shaped reference dam plate that can be installed between the pair of side walls with its front surface facing the paddy field side and has a long hole extending in the vertical direction and penetrating in the front-to-rear direction; a movable member having a flow path with an inlet located at the front side and an outlet located at the rear side, the movable member being assembled to the reference dam plate so that the flow path passes through the hole; a vertical width of the outlet of the movable member is smaller than a vertical width of the long hole of the reference dam plate, A water level adjustment device in which the movable member can be assembled to the reference weir plate at different positions in the vertical direction to change the position of the lower end of the flow path.

4. A water level adjustment device installed in a rice paddy outlet basin having a bottom wall and a pair of side walls erected opposite to each other from the bottom wall, a plate-shaped reference dam plate that can be installed between the pair of side walls with its front surface facing the paddy field side and has a long hole extending in the vertical direction and penetrating in the front-to-rear direction; a movable member having a flow path with an inlet located at the front side and an outlet located at the rear side, the movable member being assembled to the reference dam plate with the outlet facing the long hole, The movable member is capable of assembling the flow path to the reference weir plate at different vertical positions within the range extending vertically of the long hole in order to change the position of the lower end of the flow path, and the entire outlet faces the long hole at any of the different vertical positions, a water level adjustment device.

5. the reference dam plate includes a first assembly hole that is a hole extending along the extension direction of the elongated hole around the elongated hole, the movable member includes a flange portion that covers a part of the elongated hole and the first assembly hole when attached to the reference dam plate, The water level adjusting device according to any one of claims 2 to 4, wherein the flange portion is provided with a second assembly hole through which the screw passing through the first assembly hole can pass.

6. The reference dam plate further includes a drainage port penetrating in the front-rear direction below the hole, The water level adjustment device according to any one of claims 1 to 5, wherein the drain outlet is blockable.

7. The flow path on the paddy field side of the reference weir plate is formed inside a cylindrical body that is bent midway, A water level adjustment device according to any one of claims 1 to 6, wherein the height of the inlet can be changed by rotating the device around an axis located on the reference dam plate side rather than the bending point.

8. The water level adjustment device according to any one of claims 1 to 7, A water storage device comprising a lid capable of blocking the flow path or restricting the flow rate.

9. The reference dam plate further includes an overflow hole that is a hole penetrating in the front-rear direction above the hole, 9. The water storage device according to claim 8, wherein the width of the overflow hole increases upward.

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