Paddy field drainage pipe components and paddy field drainage system

Abstract

We propose a paddy field drainage pipe component that has the function of adjusting the water level to a level suitable for rice cultivation and the function of making the paddy field area usable as a paddy field dam. [Solution] The paddy field drainage pipe member 3 comprises a main pipe section 21 having a connecting port 31 connected to a connecting port 11 of a drainage pipe section 2 buried in the levee section 103, and a first inlet section at both ends that communicates with the connecting port 31 and is opened and closed by an opening / closing cover section 46, and an elbow pipe section 22 that is rotatably connected to the body of the main pipe section 21 via a rotating connecting member 23 and has a second inlet section 56 that communicates with the connecting port 31. With this paddy field drainage pipe member 3, the water level of the paddy field section 101 can be easily adjusted by rotating the elbow pipe section 22 to change the height position of the second inlet section 56, and the paddy field section 101 can be used as a paddy field dam by opening the first inlet section during heavy rain.

Description

Technical Field

[0001] The present invention relates to a paddy field drainage pipe member attached to a drainage pipe for draining water from a paddy field that can be used as a paddy field dam, and a paddy field drainage system having the paddy field drainage pipe member.

Background Art

[0002] In recent years, as a measure to prevent and mitigate flood disasters caused by heavy rain, a so-called "paddy field dam" has been proposed that can temporarily store rainwater in paddy fields to suppress a rapid increase in the water level of rivers. In the paddy field dam, for example, as in Patent Document 1, a storage amount adjustment device for adjusting the water level of the paddy field is provided on the ridge that divides the paddy field.

[0003] This storage amount adjustment device includes a bottomed box-shaped frame body that opens upward and forward, a farming water level adjustment plate that closes the front opening of the frame body, and a storage amount adjustment plate that divides the internal area surrounded by the frame body and the farming water level adjustment plate into front and rear sections. The farming water level adjustment plate is provided at a predetermined height lower than the rear side wall and the storage amount adjustment plate that constitute the frame body. A drain pipe communicating with a drainage channel is connected to the lower part of the rear side wall, and an inflow port penetrating through the front and rear is provided at the lower part of the storage amount adjustment plate. When the water level of the paddy field exceeds the farming water level adjustment plate due to rainfall, water flows into the front area partitioned by the storage amount adjustment plate and flows through the flowing water port to the drain pipe via the rear area. Thereby, the water level of the paddy field can be maintained at the farming water level, which is the height of the farming water level adjustment plate. On the other hand, during heavy rain, until the water level of the paddy field exceeds the height of the storage amount adjustment plate, drainage is carried out to the drain pipe through the flowing water port, so the amount of drainage to the drainage channel can be suppressed. When the water level of the paddy field exceeds the storage amount adjustment plate, it directly flows into the rear area and flows to the drain pipe, so the amount of drainage to the drainage channel increases. Thus, during heavy rain, since the amount of drainage flowing into the drain pipe can be adjusted according to the water level of the paddy field, the occurrence of flood disasters due to a rapid increase in water level can be suppressed.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2012-120510 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, in rice cultivation, water management of the paddy field is generally necessary from planting to harvest. Specifically, appropriate water management is carried out for each stage, such as deep water management from planting to establishment, shallow water management from establishment to tillering, mid-season drainage during the peak tillering period, and intermittent irrigation after mid-season drainage. Here, the water level of the paddy field to be managed differs between deep water management and shallow water management, and in mid-season drainage, water is drained so that the soil surface is exposed, while intermittent irrigation involves repeatedly flooding and draining the field. In this way, in rice cultivation, it is necessary to adjust the water level of the paddy field in accordance with the growth of the rice plants.

[0006] In the conventional configuration described in Patent Document 1, while it can function as a paddy field dam during heavy rains, the water level of the paddy field during normal times is adjusted using agricultural water level adjustment plates. Therefore, deep water management and shallow water management require preparing and replacing agricultural water level adjustment plates of appropriate heights, mid-season drainage requires removing the agricultural water level adjustment plates (and storage volume adjustment plates), and intermittent irrigation requires replacing or removing the agricultural water level adjustment plates for flooding and draining. However, these replacement, removal, and installation operations for agricultural water level adjustment plates are complicated, and there is also a risk of injury during these operations.

[0007] This invention proposes a paddy field drainage pipe component and a paddy field drainage system that can enable paddy fields to function as paddy field dams during heavy rains and can easily and safely adjust the water level of the paddy fields to a level suitable for rice cultivation. [Means for solving the problem]

[0008] The first aspect of the present invention is a paddy field drainage pipe member that is attached to a connected opening facing the paddy field of a drainage pipe section, which is disposed at the boundary between a paddy field section usable for a paddy field dam and a drainage channel section from which water is drained from the paddy field section, and which allows water to flow from the paddy field section to the drainage channel section, and is characterized by comprising: a connecting opening section connected to the connected opening section of the drainage pipe section; a first inlet section communicating with the connecting opening section and, when attached to the drainage pipe section, into which water from the paddy field section flows in from a position lower than the upper limit storage water level of the paddy field dam set in the paddy field section; an inlet opening / closing means for converting the first inlet section between an open state into which water can flow in and a closed state into which water cannot flow in; a second inlet section communicating with the connecting opening section and into which water from the paddy field section flows in; and an inlet position conversion means for converting the height position into which water from the paddy field section flows in the second inlet section.

[0009] In this configuration, the water level of the paddy field flowing into the second inlet can be changed by changing the height position of the second inlet. That is, by changing the height position of the second inlet while the first inlet is closed, the water level of the paddy field can be easily adjusted, making it easy to adjust to a water level suitable for rice cultivation (from planting to harvest). On the other hand, by keeping the first inlet open, even if the water level of the paddy field is lower than the upper storage water level, the water from the paddy field can be drained from the first inlet to the drainage pipe. As a result, water can be drained from the first inlet during heavy rain, which can suppress the rise in water level up to the upper storage water level, and the paddy field can be used relatively stably as a paddy field dam. Thus, the configuration of the present invention has the function of adjusting the water level suitable for rice cultivation and the function of using it as a paddy field dam, and separates the second inlet (and inlet position changing means) that performs the former function from the first inlet (and inlet opening / closing means) that performs the latter function. Therefore, according to the configuration of the present invention, the two functions described above can be easily utilized as needed.

[0010] In this configuration, the inflow position changing means is preferably configured such that the lowest possible height position of the second inlet is at or below the same height as the soil surface of the paddy field. This allows, for example, when performing mid-season drainage of rice, to drain most of the water from the paddy field through the second inlet by setting the height of the second inlet to the same height as the soil surface.

[0011] In the paddy field drainage pipe member of the present invention described above, a configuration is proposed in which the inflow position changing means is composed of the elbow pipe and the rotating connecting member, the main pipe having a connecting port at one end and a first inlet at the other end, and the connecting port and the first inlet being connected; the elbow pipe having a second inlet at one end and a connecting port at the other end that communicates with the second inlet; and a rotating connecting member that connects a connected port provided on the body of the main pipe to the connecting port of the elbow pipe, thereby communicating the connecting port and the connecting port via the connected port, and rotatably connecting the elbow pipe to the body of the main pipe, the inflow position changing means being composed of the elbow pipe and the rotating connecting member.

[0012] In this configuration, since connecting ports and first inlet ports are provided at both ends of the main pipe, water flowing in from the first inlet port when the first inlet port is open can be smoothly discharged to the drain pipe through the connecting ports. Furthermore, since the height position of the second inlet port can be changed by rotating the elbow pipe connected to the main pipe via a rotating connecting member, the height position can be changed easily and safely.

[0013] In the paddy field drainage pipe member of the present invention described above, the elbow pipe portion comprises an elbow main portion having a detachable opening at one end from which an extension pipe portion along the opening direction of the one end can be attached and detached, and a connecting opening at the other end. When the extension pipe portion is attached to the detachable opening, the tip opening of the extension pipe portion constitutes the second inlet portion, while when the extension pipe portion is not attached to the detachable opening, the detachable opening constitutes the second inlet portion.

[0014] In this configuration, by attaching the extension pipe (hereinafter referred to as the attached state), the height of the second inlet can be changed to a higher position compared to the state without the extension pipe (hereinafter referred to as the unattached state). This allows the user to select between the attached and unattached states of the extension pipe depending on the height of the levee (depth of the paddy field) and the position of the connection point of the drainage pipe, making it suitable for use in various environments.

[0015] In the paddy field drainage pipe member of the present invention described above, a configuration is proposed in which an inflow rate suppressing means is provided that is detachably attached to the first inlet portion and suppresses the amount of water flowing in from the first inlet portion when the inlet opening / closing means is open.

[0016] In this configuration, when the first inlet is open, the amount of water flowing in from the first inlet can be suppressed by the inflow suppression means, and the amount of water discharged to the drainage channel via the drainage pipe when the water level is lower than the upper limit storage level during heavy rainfall can be suppressed. As a result, the paddy field can be used more stably as a paddy field dam.

[0017] In the paddy field drainage pipe member of the present invention described above, a configuration is proposed in which a protruding pipe portion is provided so as to protrude upward from the body of the main pipe portion, and has an upper opening that communicates with the inside of the main pipe portion, located above the first inlet portion and the second inlet portion.

[0018] In this configuration, if the amount of water flowing in from the second and first inlets exceeds the amount of water to be discharged to the discharge pipe during heavy rainfall, the water can be discharged from the upper opening. This allows the flow of water from the second and first inlets to the discharge pipe to be maintained even when the inflow volume is increased, and the desired drainage function can be stably maintained. In addition, the interior can be inspected using the upper opening, allowing for maintenance work and removal of accumulated debris.

[0019] The second aspect of the present invention is a paddy field drainage system for draining water from a paddy field area that can be used as a paddy field dam, which is disposed at a boundary between the paddy field area and a drainage channel area where water from the paddy field area is drained, has a connected port portion facing the paddy field area on the upstream side, and has a drainage port portion communicating with the connected port portion and facing the drainage channel area on the downstream side. The paddy field drainage system is characterized by comprising a drain pipe portion and a paddy field drain pipe member of the first invention attached to the connected port portion of the drain pipe portion for flowing water in the paddy field area into the drain pipe portion.

[0020] In such a configuration, since it includes the paddy field drain pipe member of the first invention, it can exhibit the same operational effects as the first invention.

[0021] In the paddy field drainage system of the present invention described above, a configuration is proposed in which the paddy field drain pipe member is detachably attached to the first inlet portion and includes an inflow amount suppressing means for suppressing the inflow amount of water flowing in from the first inlet portion in an open state of the inlet opening / closing means.

[0022] In such a configuration, since the inflow amount of water at the open first inlet portion can be suppressed, the drainage amount discharged to the drainage channel area in a state below the upper limit storage water level during heavy rain can be suppressed, and the paddy field area can be stably used as a paddy field dam.

Effects of the Invention

[0023] In the paddy field drain pipe member of the present invention, since it has a function of adjusting the water level suitable for rice cultivation and a function of being used as a paddy field dam, these functions can be properly used as needed, and both functions can be easily utilized.

[0024] In the paddy field drainage system of the present invention, since it includes the paddy field drain pipe member of the present invention described above, it exhibits the same operational effects as the paddy field drain pipe member.

Brief Description of the Drawings

[0025] [Figure 1] It is a longitudinal sectional view showing the construction state of the paddy field drainage system 1 of the present invention. [Figure 2] (A) Plan view and (B) side view of the paddy field drain pipe member 3 of the present invention. [Figure 3] It is an explanatory view showing a mode of rotating the elbow pipe portion 22 of the paddy field drain pipe member 3. [Figure 4] (A) Cross-sectional view and (B) longitudinal sectional view of the paddy field drain pipe member 3 in the closed state of the first inlet portion 32. [Figure 5] (A) Cross-sectional view and (B) longitudinal sectional view of the paddy field drain pipe member 3 in the open state of the first inlet portion 32. [Figure 6] It is an explanatory view showing a mode of rotating the elbow pipe portion 22 in the non-attached state of the extension pipe portion 55.

Embodiments for Carrying Out the Invention

[0026] Examples embodying the paddy field drain pipe member and the paddy field drainage system according to the present invention will be described in detail below. Note that since the paddy field drainage system 1 of this example is for flowing water from the paddy field portion 101 to the drainage path portion 102, the description will be made with the paddy field portion side as the upstream and the drainage path portion side as the downstream.

[0027] Fig. 1 shows the paddy field drainage system 1 of this example. The paddy field drainage system 1 has a function of adjusting the water level of the paddy field portion 101 to a level suitable for rice cultivation and a function of being able to use the paddy field portion 101 as a so-called paddy field dam during heavy rain, and is provided at the ridge portion 103 at the boundary between the paddy field portion 101 and the drainage path portion 102. Here, the drainage path portion 102 is for flowing the water discharged from the paddy field portion 101 to a downstream river or the like, and is formed in a substantially U-shaped cross-section by, for example, concrete. In the paddy field portion 101, an upper limit storage water level S when used as the paddy field dam is preset. The paddy field portion 101 functions as the paddy field dam that suppresses the amount of drainage to the downstream river by storing water up to the upper limit storage water level S during heavy rain. Note that in this example, the ridge portion 103 corresponds to the boundary portion according to the present invention.

[0028] The paddy field drainage system 1 consists of a drainage pipe section 2 and a paddy field drainage pipe member 3 connected together. The drainage pipe section 2 is buried in the levee section 103, and the paddy field drainage pipe member 3 is connected to the upstream end of the drainage pipe section 2.

[0029] The drain pipe section 2 is a tubular shape with a circular cross-section, in which a connecting port 11 opened at the upstream end and a drain outlet 12 opened at the downstream end are connected, and is buried in the levee section 103 as described above. The connecting port 11 of the drain pipe section 2 is positioned so that it opens laterally on the side of the paddy field section 101 and faces the interior of the paddy field section 101. The drain outlet 12 is fitted into a through hole (not shown) that penetrates the side wall section 102a of the drainage channel section 102, and the drain outlet 12 is positioned so that it faces the interior of the drainage channel section 102. In this embodiment, the drain pipe section 2 has a substantially uniform inner diameter from the upstream connecting port 11 to the downstream drain outlet 12.

[0030] As shown in Figures 2-5, the paddy field drainage pipe member 3 comprises a main pipe section 21 and an elbow pipe section 22, with the elbow pipe section 22 connected by a rotating connecting member 23. Here, the main pipe section 21, the elbow pipe section 22, and the rotating connecting member 23 are molded from a resin material. This resin material can be polyvinyl chloride resin or polypropylene resin, among others. Among polyvinyl chloride resins, rigid polyvinyl chloride resin is preferably used.

[0031] The main pipe section 21 is tubular in shape, with a connecting port 31 at one end and a first inlet section 32 at the other end. The connecting port 31 and the first inlet section 32 are in communication. Furthermore, the body section 25 of the main pipe section 21 between the connecting port 31 and the first inlet section 32 is provided with an upwardly projecting protruding pipe section 26 and a laterally branched branch pipe section 27 (Figures 4 and 5), and the elbow pipe section 22 is connected to the branch pipe section 27 via the rotating connecting member 23. The upper opening 33 at the upper end of the protruding pipe section 26 is in communication with the connecting port 31, and the connected port 34 at the branch pipe section 27 is in communication with the connecting port 31 (Figures 4 and 5).

[0032] The connecting port 31 of the main pipe section 21 is formed in a flange shape that is fitted onto the receiving port 11 of the drain pipe section 2. By fitting the connecting port 31 onto the receiving port 11 and connecting them, the paddy field drain pipe member 3 is attached to the drain pipe section 2, and in this attached state, the connecting port 31 communicates with the drain pipe section 2. In addition, the first inlet portion 32 of the main pipe section 21 is formed in a flange shape that is fitted onto the flow rate suppressing member 41, which will be described later, and the flow rate suppressing member 41 is fitted onto the first inlet portion 32 and attached (see Figures 4 and 5).

[0033] As shown in Figures 4 and 5, the inflow rate suppressing member 41 comprises a funnel-shaped portion 43 with an inflow narrow opening 42 having a smaller diameter than the first inlet portion 32 that opens outward, and a fitting ring portion 44 connected to the outer peripheral edge of the funnel-shaped portion 43. The fitting ring portion 44 is fitted into the first inlet portion 32, thereby attaching it to the main pipe portion 21. When attached to the first inlet portion 32 of the main pipe portion 21, the inflow narrow opening portion 42 is positioned offset towards the lower edge of the first inlet portion 32. With the inflow rate suppressing member 41 attached, the first inlet portion 32 communicates with the outside through the inflow narrow opening portion 42, and the amount of water flowing into the first inlet portion 32 is suppressed by the inflow narrow opening portion 42. In this embodiment, the inflow rate suppressing member 41 is configured to be held in place when attached to the first inlet portion 32. This inflow rate suppressing member 41 corresponds to the inflow rate suppressing means according to the present invention.

[0034] An opening / closing cover 46 is attached to the inflow rate suppressing member 41 to open and close the inflow narrow opening 42. By attaching this opening / closing cover 46, the inflow narrow opening 42 (first inlet 32) is closed, and by removing the opening / closing cover 46, the inflow narrow opening 42 is opened. A locking mechanism (not shown) is provided to hold the opening / closing cover 46 in the closed state. The opening / closing cover 46 corresponds to the inlet opening / closing mechanism according to the present invention. Here, as a locking mechanism, for example, a configuration can be applied that includes a groove provided on the inner circumferential surface of the inlet narrow opening 42 and a projection provided on the outer circumferential surface of the opening / closing lid 46. More specifically, the groove comprises a guide groove in the front-rear direction along the inlet narrow opening 42 and an arc-shaped retaining groove that is continuous in the circumferential direction from the rear end of the guide groove. When attaching the opening / closing lid 46 to the inlet narrow opening 42, the projection of the inlet narrow opening 42 is inserted into the guide groove, and then the opening / closing lid 46 is rotated along the retaining groove. This prevents the opening / closing lid 46 from moving in the front-rear direction and holds it in a closed state. When removing the opening / closing lid 46, the opening / closing lid 46 is rotated to move the projection to the guide groove, and then moved forward. This allows the opening / closing lid 46 to be removed.

[0035] Furthermore, as shown in Figures 4(A) and 5(A), an annular rotating connecting member 23 is fixed to the edge of the connection port 34 of the branch pipe section 27 of the main pipe section 21, and one end of the elbow pipe section 22 is rotatably connected to the rotating connecting member 23. The elbow pipe section 22 comprises an elbow main body 51 that has a curved pipe shape, with a detachable port 52 provided at one end of the elbow main body 51, and a connecting port 53 that communicates with the detachable port 52 provided at the other end. The connecting port 53 is rotatably connected to the rotating connecting member 23, and the elbow main body 51 (elbow pipe section 22) is rotatably connected to the branch pipe section 27 by the rotating connecting member 23. On the other hand, the detachable port 52 is formed in a flange shape into which a straight pipe-shaped extension pipe section 55 is detachably fitted. Then, with the extension pipe section 55 fitted and installed in the attachment / detachment port section 52, the tip opening 56 of the extension pipe section 55 communicates with the connection port section 53 of the elbow main body section 51 via the attachment / detachment port section 52. In other words, the tip opening 56 of the extension pipe section 55 communicates with the connecting port section 31 of the main pipe section 21 via the elbow main body section 51. When the extension pipe section 55 is installed, the tip opening 56 corresponds to the second inlet section according to the present invention, and the elbow pipe section 22 is formed by the extension pipe section 55 and the elbow main body section 51.

[0036] As shown in Figures 2 and 3, the elbow pipe section 22 connected to the main pipe section 21 can be rotated vertically relative to the main pipe section 21, and this rotation allows the height position of the tip opening (second inlet) 56 of the elbow pipe section 22 to be changed. Here, the length of the extension pipe section 55 is determined such that, when the tip opening 56 of the elbow pipe section 22 is in its highest position (Figure 2), the tip opening 56 is lower than the upper opening 33 of the protruding pipe section 26.

[0037] In this embodiment, the body portion 25 of the main pipe portion 21 has a ridge-shaped guide ridge 29 that rises inward at the lower part of its inner circumference (see Figures 2(A), 4(A), and 5(A)). This guide ridge 29 allows water flowing from the elbow pipe portion 22 into the main pipe portion 21 to be guided to the connecting port portion 31.

[0038] Next, the usage of the paddy field drainage system 1 in this embodiment will be described. As shown in Figure 1, the connecting port 31 of the paddy field drain pipe member 3 is connected to the connecting port 11, which is opened laterally on the side of the paddy field section 101 of the drain pipe section 2 buried in the levee section 103, thereby attaching the paddy field drain pipe member 3 to the drain pipe section 2. In this attached state, the paddy field drain pipe member 3 is installed exposed inside the paddy field section 101. Here, the paddy field drain pipe member 3 is attached to the drain pipe section 2 with its upper opening 33 facing upward, and the main pipe section 21 is placed on the soil surface of the paddy field section 101. Furthermore, the inlet narrow port 42 (main inlet 32) of the inflow rate suppressing member 41 is positioned lower than the upper limit storage water level S, while the upper opening 33 of the protruding pipe section 26 is positioned higher than the upper limit storage water level S. Furthermore, in this embodiment, with the elbow pipe section 22 facing upward along a substantially vertical direction (Figure 2(B)), the height position of the second inlet section (tip opening) 56 is set to be approximately the same as the upper limit storage water level S. With the paddy field drainage pipe member 3 arranged in this manner, the height position of the second inlet section (tip opening) 56 can be changed within a range below the upper limit storage water level S by rotating the elbow pipe section 22 in the vertical direction. In addition, if the elbow pipe section 22 is positioned along a substantially horizontal direction, the lower end of the second inlet section 56 will be close to the soil surface of the paddy field section 101, so that almost all of the water from the paddy field section 101 can flow into the second inlet section 56.

[0039] Under normal conditions, the inlet narrow opening 42 of the inlet volume suppressing member 41 of the paddy field drainage pipe member 3 is held in a closed state by having an opening / closing cover 46 attached to it.

[0040] With the paddy field drainage system 1 installed in this manner, the water level of the paddy field 101 can be adjusted for deep water management, shallow water management, mid-season drainage, and intermittent irrigation in rice cultivation. For example, when performing deep water management, the elbow pipe section 22 is rotated to position the second inlet section (tip opening) 56 at a height that matches the water level for deep water management (see Figure 3(A)). This allows the water level of the paddy field 101 to be managed as deep water. When performing shallow water management, the elbow pipe section 22 is rotated downward from the height position for deep water management to position the second inlet section 56 at a height that matches the water level for shallow water management (see Figure 1). This allows the water level of the paddy field 101 to be managed as shallow water. Furthermore, when performing mid-season drainage, the elbow pipe section 22 is rotated downward so that it is aligned approximately horizontally (see Figure 3(B)). As a result, the lower end of the second inlet section 56 is positioned at a height close to the soil surface of the paddy field section 101, allowing most of the water in the paddy field section 101 to be drained from the second inlet section 56, thus enabling the paddy field section 101 to be partially drained. Furthermore, when intermittent irrigation is performed, both flooding management and drainage management are carried out, so the height of the second inlet section 56 is set to match the water level for flooding management, and the height of the second inlet section 56 is changed to match the drainage management. In this way, by rotating the elbow pipe section 22 up and down to change the height of the second inlet section 56 to a position suitable for deep water management, shallow water management, partial drainage, and intermittent irrigation, the water level of the paddy field section 101 can be properly adjusted.

[0041] Here, if a large amount of water flows in from the second inlet section 56 due to rainfall or the like, and the amount of water flowing in exceeds the amount of water that can be drained into the drainage pipe section 2, the water that cannot be drained into the drainage pipe section 2 will accumulate in the main pipe section 21 and will be discharged into the paddy field section 101 from the upper opening 33 of the protruding pipe section 26.

[0042] On the other hand, during heavy rainfall, the paddy field section 101 is used as a paddy field dam. In this case, the elbow pipe section 22 is positioned almost vertically, and the second inlet section 56 is positioned upward (see Figure 2), and the opening / closing cover section 46 is removed to open the inlet narrow opening section 42 (see Figure 5). When the water level in the paddy field section 101 is lower than the upper limit storage water level S, water flows in from the inlet narrow opening section 42 (first inlet section 32) and is drained to the drainage channel section 102 via the drainage pipe section 2. Also, when the water level in the paddy field section 101 rises and exceeds the upper limit storage water level S, water flows in from the second inlet section 56 and is drained to the drainage channel section 102.

[0043] Here, the narrow inlet section 42 has a smaller diameter than the second inlet section 56, and therefore functions as a so-called orifice that suppresses the amount of water flowing in from the paddy field section 101. As a result, the amount of water drained to the drainage channel section 102 can be suppressed until the water stored in the paddy field section 101 exceeds the upper storage water level S, and rainwater is stored in the paddy field section 101. After this, when the water level in the paddy field section 101 rises and exceeds the upper storage water level S, water flows in from the second inlet section 56, so the amount of water drained to the drainage channel section 102 increases, and the increase in the amount of water stored in the paddy field section 101 can be suppressed.

[0044] In this way, during heavy rainfall, the paddy field section 101 can be used as a paddy field dam, suppressing the amount of water flowing into the downstream river and preventing or mitigating flood damage in the downstream area.

[0045] Furthermore, the paddy field drainage pipe member 3 described above can also be used without attaching the extension pipe section 55 to the elbow main body 51. As shown in Figure 6, the extension pipe section 55 is not attached to the attachment / detachment port 52 of the elbow main body 51, and the elbow pipe section 22 is formed by the elbow main body 51, with the attachment / detachment port 52 of the elbow main body 51 serving as the second inlet. In this case, the height position of the second inlet section (attachment / detachment port) 52, which is changed according to the rotation angle of the elbow pipe section 22, becomes lower than the height position of the second inlet section (tip opening) 56 when the extension pipe section 55 is attached (see Figures 2 and 3). Therefore, by selecting and using the state with or without the extension pipe section 55 attached, depending on the usage environment such as the water level adjusted in the paddy field section 101, the upper limit storage water level S, and the height of the levee section 103, the water level can be adjusted to suit the usage environment.

[0046] The paddy field drainage system 1 (paddy field drainage pipe member 3) of this embodiment has the function of adjusting the water level of the paddy field section 101 by rotating the elbow pipe section 22 to change the height position of the second inlet section (tip opening) 56, and also has the function of being able to use the paddy field section 101 as a paddy field dam by opening the inlet narrow opening section 42 (first inlet section 32) during heavy rains, etc. The former function (water level adjustment function) can be used by rotating the elbow pipe section 22, and the latter function (paddy field dam function) can be used by opening and closing the opening / closing cover section 46, so these two functions can be easily used as needed. Furthermore, the configuration of this embodiment does not require the replacement of the agricultural water level adjustment plate for water level adjustment, as described above, so accidents such as using the wrong agricultural water level adjustment plate or getting injured during replacement work can be suppressed.

[0047] The present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, the dimensions and shapes of each part in the embodiments described above can be changed as appropriate.

[0048] The paddy field drainage pipe member in the above-described embodiment has a straight main pipe section, but it is not limited to this, and may also have a curved main pipe section or a roughly L-shaped main pipe section. For example, in a configuration with a roughly L-shaped main pipe section, it has a connecting port section that opens downward and a first inlet section that opens laterally, and the connecting port section is connected to and attached to the connecting port section of the drainage pipe section, which has an upward-opening connecting port section. Even in this configuration with a main pipe section, by providing an elbow pipe section and a protruding pipe section as in the above-described embodiment, the same effects and advantages as in the embodiment can be achieved. Alternatively, it is also possible to have a straight pipe section with an upward-opening upper opening and a downward-opening connecting port section at both ends, and a first inlet section is provided at the end of a protruding pipe section that protrudes laterally from the body of the straight pipe section. In this configuration, by providing an elbow pipe section on the body of the straight pipe section as in the above-described embodiment, the same effects and advantages as in the embodiment can be achieved.

[0049] The paddy field drainage pipe component of the embodiment described above has an inflow rate suppressing member attached to the first inlet of the main pipe section, but it is not limited to this configuration, and a configuration without an inflow rate suppressing member is also possible. In this configuration, it is preferable that the first inlet section has a smaller diameter than the second inlet section. And even in this configuration, as in the embodiment described above, it is equipped with an opening / closing cover that opens and closes the first inlet section, and by removing the opening / closing cover during heavy rain, it can be used as a paddy field dam.

[0050] The paddy field drainage pipe member in the embodiment described above has a protruding pipe section that extends upward from the body of the main pipe section, but it is not limited to this configuration, and a configuration without a protruding pipe section is also possible. That is, the body of the main pipe section, which has a first inlet section and a connecting section at both ends, is provided only with a branch pipe section, and an elbow pipe section is connected to the branch pipe section via a rotating connecting member. In this configuration, the height position of the second inlet section can be adjusted by rotating the elbow pipe section, thus providing the function of adjusting the water level in the paddy field and the function of being usable as a paddy field dam, similar to the embodiment described above. Furthermore, by orienting the second inlet section upward, it is also possible to perform maintenance work etc. through the second inlet section. [Explanation of Symbols]

[0051] 1. Paddy field drainage system 2 Drain pipe section 3. Paddy field drainage pipe components 11 Connected port 12 Drain port 21 Main pipe section 22 Elbow pipe section 23 Rotating connecting member 25 Torso 26 Projecting tube part 31 Connection port 32 First inlet part 33 Upper opening 34 Connection port 41. Inflow rate suppression member (inflow rate suppression means) 42 Narrow inlet part 46. ​​Opening / closing lid section (inlet opening / closing mechanism) 51 Elbow main body 52 Detachment port (second inlet port) 53 Connection port 55 Extension pipe section 56 Tip opening (second inlet) 101 Rice Paddy Section 102 Drainage section 102a Side wall part 103 Ridge area (border area) S Upper limit of storage water level

Claims

1. A paddy field drainage pipe member is installed at the boundary between a paddy field area usable for a paddy field dam and a drainage channel area from which water is drained from the paddy field area, and is attached to the connected opening facing the paddy field area of ​​a drainage pipe section that drains water from the paddy field area to the drainage channel area, and is used to allow water to flow from the paddy field area to the drainage pipe section. A connecting port that is connected to the connecting port of the drain pipe section, A first inlet section is connected to the aforementioned connecting port and attached to the aforementioned drainage pipe section, into which water from the paddy field flows in from a position lower than the upper limit storage water level of the paddy field dam set in the paddy field section, The inlet opening and closing means converts the first inlet section between an open state in which water can flow in and a closed state in which water cannot flow in, A second inlet section is connected to the aforementioned connecting port and into which water from the paddy field flows, The inlet position changing means for changing the height position at which water from the paddy field flows into the second inlet section, A paddy field drainage pipe member characterized by having the following features.

2. A main pipe section is provided with the connecting port at one end and the first inlet at the other end, and the connecting port and the first inlet are connected. An elbow pipe section having the second inlet section at one end and a connecting port section communicating with the second inlet section at the other end, A rotating connecting member is provided which connects the connection port provided on the body of the main pipe and the connection port of the elbow pipe, thereby connecting the connection port and the connecting port via the connection port, and which rotatably connects the elbow pipe to the body of the main pipe. Equipped with, The paddy field drainage pipe member according to claim 1, characterized in that the inflow position changing means is composed of the elbow pipe portion and the rotating connecting member.

3. The aforementioned elbow pipe section is, The elbow body is provided with a detachable port at one end, from which an extension pipe portion along the opening direction of the one end can be attached and detached, and the other end is provided with the aforementioned connection port. The paddy field drainage pipe member according to claim 2, characterized in that when the extension pipe is attached to the detachable opening, the tip opening of the extension pipe constitutes the second inlet, while when the extension pipe is not attached to the detachable opening, the detachable opening constitutes the second inlet.

4. The paddy field drainage pipe member according to any one of claims 1 to 3, characterized in that it is detachably attached to the first inlet and includes an inflow rate suppressing means for suppressing the amount of water flowing in from the first inlet when the inlet opening / closing means is open.

5. The paddy field drainage pipe member according to claim 2 or 3, characterized in that it is provided with a protruding pipe portion that is provided so as to protrude upward from the body of the main pipe portion and has an upper opening that communicates with the inside of the main pipe portion above the first inlet portion and the second inlet portion.

6. A paddy field drainage system for draining water from paddy fields that can be used as a paddy field dam, A drainage pipe section is provided at the boundary between the paddy field section and the drainage channel section from which the water from the paddy field section is drained, and has a connecting port facing the paddy field section on the upstream side and a drainage port communicating with the connecting port and facing the drainage channel section on the downstream side, A paddy field drain pipe member according to any one of claims 1 to 3, which is attached to the connected opening of the drain pipe section and allows water from the paddy field section to flow to the drain pipe section. A paddy field drainage system characterized by being equipped with the following features.

7. The aforementioned paddy field drainage pipe member is The paddy field drainage system according to claim 6, further comprising an inflow rate suppression means that is detachably attached to the first inlet and suppresses the amount of water flowing in from the first inlet when the inlet opening / closing means is open.

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