JP2021161723A - Boom and fish passage - Google Patents

Abstract

To provide a boom in which passage of creatures is possible even when a water level is lowered.SOLUTION: A boom 1 comprises: ropes 10, 20 bridged in a prescribed water area; a plurality of floats 30 connected with the ropes 10, 20; and nets 40, 50 connected with the ropes 10, 20 or the floats 30 and at least a part of which is positioned underwater. The boom 1 includes a fish passage 60 positioned below a water surface. The fish passage 60 includes: at least two opening portions 63 opened with the nets 40, 50 interposed therebetween, in or below the nets 40, 50; and a path 64 connecting the opening portions 63 with each other. The narrowest area of the opening portions 63 and the path 64 is larger than an area of a mesh of the net.SELECTED DRAWING: Figure 3

Description

The present invention relates to a net field and a fishway, and more particularly to a net field used as a driftwood stop facility in a river, a lake, a dam lake, etc., and a fishway used therefor.

In rivers, lakes, dam lakes, etc., net fields are used for the purpose of damming dust such as driftwood. For example, in the case of a dam, this net field is a rope that is laid across the dam lake, multiple floats (floats) connected to the rope, between adjacent floats, and in the water under the float. Has an expanded net. Then, this net dams up and collects dust such as driftwood flowing from the upstream of the dam (Patent Document 1).

By the way, as shown in FIG. 9, since the net deployed underwater has a certain height (depth) from the water surface, there is a distance from the lower end of the net to the bottom of the dam lake when the dam lake is full. , The net does not impede the movement of aquatic organisms, such as seafood, that inhabit the dam lake. In FIG. 9, the space between the net and the lake bottom is shown narrowly to illustrate the lake bottom, but if the dam lake is full, there is a distance of 10 m or more between the bottom of the net and the lake bottom.

Japanese Unexamined Patent Publication No. 2008-038337

However, the amount of water stored in the dam lake fluctuates depending on the amount of water flowing into the dam and the amount of water discharged from the dam, and when the amount of water stored in the dam lake decreases, such as when the dam lake is in a dry season, the water level drops. The lower end may land on the bottom of the dam lake.

Then, as shown in FIG. 10, the landed net divides the dam lake, and aquatic organisms living in the dam lake, especially organisms larger than the eyes of the net, can come and go across the net. become unable.

Therefore, the present invention is to provide a net field and a fishway capable of allowing organisms to come and go even when the water level drops.

In order to solve the above problem, claim 1 is that a rope spanned in a predetermined water area, a plurality of floats connected to the rope, and at least a part of the rope or the float connected to the float are located in water. A net field provided with a net, wherein the net field has a fishway located in water, and the fishway has an opening that opens across the net and the opening under the net. It is characterized by having a passage communicating with the portion, and the area of the opening and the narrowest portion of the passage is larger than the area of the mesh of the net. As a result, an opening larger than the mesh area of the net is located across the net, and a fishway with a passage communicating with the opening is located. Therefore, even if the net is seated on the bottom of the lake, organisms pass through the fishway. You can come and go.

Claim 2 is that the fishway is a cylindrical body made of synthetic resin. As a result, a fishway can be easily formed.
In claim 3, the fishway is suspended from a rope. As a result, the fishway can be easily arranged.

A fourth aspect of the present invention is a net including a rope spanning a predetermined water area, a plurality of floats connected to the rope, and a net connected to the rope or the float and at least a part of which is located in water. A fishway provided in a field, the fishway is located in water, and the fishway is a passage connecting the net or at least two openings that open across the net and the openings to each other. The area of the opening and the narrowest part of the passage is larger than the area of the mesh of the net. As a result, by attaching the fishway to the net, it has the same effect as that of claim 1.

Claim 5 is that the fishway is a cylindrical body made of synthetic resin. As a result, by attaching the fishway to the net, it has the same effect as in claim 2.

According to the net field and fishway of the present invention, it is possible to allow organisms to come and go even when the water level drops.

The schematic diagram of the net field of this embodiment. Partially enlarged view of Amiba. Partial perspective view of Amiba. The schematic diagram explaining the state of a net field at a high water level. The schematic diagram explaining the state at the time of the low water level of the net field. a to d are perspective views showing an example of changing the fishway. a to d are schematic diagrams showing an example of changing the fishway. a is a side view showing an example of changing the fishway, and b is a rear view. Explanatory drawing at the time of high water level of the conventional net field. Explanatory drawing at low water level of conventional net field.

Hereinafter, an embodiment of a net field for a dam lake that embodies the present invention will be described with reference to FIGS. 1 to 5.
FIG. 1 shows a schematic view of the net field 1 arranged on the dam lake. As shown in the figure, the net field 1 includes an upper main rope 10 and a lower main rope 20 as ropes straddled across the dam lake. Further, the net field 1 is an upper part as a net stretched between a float 30 arranged between the upper main rope 10 and the lower main rope 20 at regular intervals in the length direction of each rope and an adjacent float 30. It includes a net 40, a lower net 50 as a net suspended from a lower main rope 20 into the water of a dam lake, and a fishway 60 arranged under the lower net 50.

Concrete anchor blocks 71 are installed on both banks of the dam lake, and anchor metal fittings 72 are embedded in both anchor blocks 71 at positions facing the dam lake with an interval of about 50 cm above and below. A metal chain (not shown) having a length of about 2 m is connected to each anchor metal fitting 72. The upper main rope 10 is connected to the metal chain connected to the upper anchor metal fitting 72, and the lower main rope 20 is connected to the metal chain connected to the lower anchor metal fitting 72, whereby the upper main rope 10 and the lower part are connected. Each of the main ropes 20 is straddled over the dam lake so as to cross the dam lake.

The upper main rope 10 and the lower main rope 20 are wire ropes in which a plurality of strands obtained by twisting strands of polyester coated with polyethylene are twisted, and have a diameter of about 30 mm. Further, the lengths of the upper main rope 10 and the lower main rope 20 are appropriately determined according to the distance between the anchor blocks 71. However, in a dam lake, the required length of the rope spanning the dam lake also changes due to changes in the water level, so the rope length will be determined individually according to the conditions of each dam lake.

As shown in FIG. 2, floats 30 and upper nets 40 are alternately arranged between the upper main rope 10 and the lower main rope 20 along the extending direction of the upper main rope 10 and the lower main rope 20. ..

As shown in FIGS. 2 and 3, the float 30 is a float made of hollow polyethylene formed in a substantially cylindrical shape having a length of about 1 m and a diameter of about 60 cm, and the inside is filled with Styrofoam (not shown). On the outer peripheral surface of the float 30, five annular recesses 31 orbiting the outer peripheral surface are formed substantially evenly in the axial direction of the float 30. Further, mounting plates 32 extending in the radial direction through the center of the same end surface are formed on both end faces in the axial direction of the float 30, and end mounting holes 33 are provided on both upper and lower ends of each mounting plate 32 toward the center. Central mounting holes 34 are formed through the two locations.

Each float 30 is located between the upper main rope 10 and the lower main rope 20, and the upper end mounting hole 33 of the float 30 and the upper main rope 10 are connected by a binding rope 35, and the lower end mounting is performed. The hole 33 and the lower main rope 20 are connected by a binding rope 35. Further, the float binding rope 36 is wound around the annular recesses 31 located at both ends in the axial direction of the float 30, the upper main rope 10 and the lower main rope 20, and the float 30, the upper main rope 10 and the lower portion are also wound in this portion. The main rope 20 is connected. The lower part of the float 30 is located in water in the state shown in FIGS. 1 to 3.

The upper net 40 is a rectangular net having a length of about 1.5 m and a height of 50 cm. The upper net 40 is a knotless net using a polyethylene thread having a diameter of 4 mm, and has a mesh size of 5 cm and a square mesh size. Since the upper net has a square mesh, the mesh shape is approximately square with a length of about 5 cm and a width of about 5 cm, and the area of each mesh is about 25 square cm.

The upper net 40 is deployed on and under water with its side 41 connected to the float 30, the upper side 42 connected to the upper main rope 10, and the lower side 43 connected to the lower main rope 20. Specifically, as shown in FIGS. 2 and 3, the side side 41 of the upper net 40 and the mounting plate 32 of the float 30 are in an adjacent positional relationship. Then, among the meshes formed on the side sides 41 of the upper net 40, the meshes adjacent to the end mounting holes 33 and the center mounting holes 34 formed in the mounting plate 32 of the float 30 are end-mounted, respectively. It is connected to the hole 33 or the central mounting hole 34 by a binding rope 44.

Further, the upper side 42 of the upper net 40 and the upper main rope 10 and the lower side 43 of the upper net 40 and the lower main rope 20 are adjacent to each other. Then, among the meshes formed on the upper side 42 and the lower side 43 of the upper net 40, at regular intervals, for example, every other mesh and the upper main rope 10 or the lower main rope 20 are connected by a binding rope 44. Since the number of binding ropes 44 is large in FIGS. 2 and 3, only some of the binding ropes 44 are designated by reference numerals.

The lower net 50 is a rectangular net having a length of about 25 m and a height of about 1.5 m. The lower net 50 is connected to the side side 51 of the adjacent lower net 50 by a binding rope (not shown), and the lower net 50 is formed in an elongated shape as a whole. The lower net 50 may mean not only the individual lower nets 50 but also a long-shaped aggregate in which a plurality of these are connected.

The lower net 50 has a side side 51 located vertically below the center of the float 30 in the axial direction, and adjacent lower nets 50 are connected to each other. The upper side 52 of the lower net 50 is connected to the lower main rope 20 and the float 30. In the connection with the lower main rope 20, at regular intervals among the meshes formed on the upper side of the lower net 50, for example, every other mesh and the lower main rope 20 are connected by a binding rope 44.

Further, a float binding rope 36 connecting the upper main rope 10 and the lower main rope 20 and the float 30 is wound around the mesh of the upper side 52 of the lower net 50. Like the upper net 40, the lower net 50 is a knotless net using a polyethylene thread having a diameter of 4 mm, has a mesh size of 5 cm, and has a square mesh and a mesh area of about 25 square cm, which is the same as the lower net 50. .. The fishway 60 is composed of a rigid polyvinyl chloride pipe (PVC pipe) 61 having a diameter of about 42 cm (inner diameter 40 cm) and a length of about 2 m. The sides are connected and integrated. The individual PVC pipes 61 form the fishway 60.

As shown in FIGS. 2, 3 and 4, each PVC pipe 61 is suspended from the lower main rope 20 by a hanging rope 62a and is arranged below the lower side 53 of the lower net 50. Specifically, the hanging rope 62a is suspended by connecting the upper portion to the lower main rope 20 and suspending the PVC pipe 61 by winding the lower portion around the PVC pipe 61. The intermediate portion of the hanging rope 62a passes through the mesh of the lower net 50 in a zigzag manner, wraps around the lower side 53 of the lower net 50, and reaches the PVC pipe 61.

Further, an anti-sway rope 62b for preventing pitching and rolling of the PVC pipe 61 is suspended in a state where the intermediate portion is circulated around the lower main rope 20, and both ends thereof are tied to both ends of the PVC pipe 61. There is. Each PVC pipe 61 has a cylindrical shape having openings 63 at both ends, and one opening 63 is opened at a position protruding toward the front side in FIG. 3 with the lower net 50 interposed therebetween, and the other opening 63 is formed. Is open at a position protruding to the back side in the drawing with respect to the lower net 50. Therefore, the two openings 63 of the PVC pipe 61 are open on both sides of the lower net 50.

It should be noted that the opening with the lower net 50 in between is not limited to the case where the opening is made by penetrating and sandwiching the lower net 50 that is actually suspended (a mode of the modified example shown in FIG. 7a), as well as the lower part. The concept includes a case where the net 50 is opened by sandwiching the virtual net 55 (broken line in FIG. 4) assuming that the net 50 is extended downward. The fishway 60 of the present embodiment shown in FIGS. 1 to 5 has a mode in which it has two openings 63 that open across a virtual net 55 assuming that the lower net 50 is extended downward, and this is also a lower net 50. It is included in the concept of opening across.

Then, the inside of the front opening 63 and the back opening 63 of the PVC pipe 61 becomes a passage 64 connecting both openings 63. The inner diameter of each PVC pipe 61 is a constant shape of 40 cm, and its area (referred to as a cross-sectional area; the same applies hereinafter) is about 1260 square cm. Here, the front and the back are relative expressions, and if the directions in FIG. 3 differ by 180 degrees in the horizontal direction, the front and the back will also be interchanged.

Next, the operation of Aba 1 of the present embodiment will be described.
FIG. 4 shows a state at a high water level where there is sufficient water in the dam lake, and since there is a sufficient distance between the net field 1 and the lake bottom (not shown), aquatic organisms sandwich the net field 1. Even when moving, it is sufficient to pass under the net field 1, and the net field 1 does not hinder the traffic of aquatic organisms.

On the other hand, as shown in FIG. 5, when the dam lake becomes drought and the water level is low, the entire net field 1 also drops accordingly, and when the water level becomes about 1.5 to 2 m or less, the net field 1 of the present embodiment The lower end will land on the bottom of the lake.

Since the net field 1 of the present embodiment has a PVC pipe 61 which is a fishway 60, even when the net field 1 has landed, only the lower net 50 overlaps the PVC pipe 61 and both openings 63 of the PVC pipe 61 are opened. Not blocked. Therefore, after entering the PVC pipe 61 through one opening 63 of the PVC pipe 61, the aquatic organism goes out of the PVC pipe 61 through the other opening 63 sandwiching the lower net 50 through the passage 64. It is possible to come and go across the Amiba 1.

According to Aba 1 of the above embodiment, the following effects can be obtained.
(1) In the above embodiment, the fishway 60 is provided in the net field 1 with an opening 63 that opens across the lower net 50 and a passage 64 that communicates with the opening 63. Therefore, even if the water level of the dam lake drops and the Aba 1 bottoms out, aquatic organisms can come and go across the Aba 1 by passing through the fishway 60.

(2) In the above embodiment, the PVC pipe 61 is used as the fishway 60. Since the PVC pipe 61 is abundant in size and easily available, the fishway 60 can be produced at low cost.
(3) In the above embodiment, the fishway 60 is suspended by a hanging rope 62a so as to be located below the lower net 50. Therefore, the fishway 60 can be easily arranged, and the fishway 60 can be provided as a retrofit configuration to the net field 1 without the fishway 60.

(4) In the above embodiment, the hanging rope 62a is passed through the mesh of the lower net 50 in a zigzag manner, and is wound around the lower side 53 of the lower net 50, and the lower part is wound around the PVC pipe 61 and suspended. Therefore, by passing the hanging rope 62a through the mesh of the lower net 50, the lower net 50 can be deployed in water without sagging by utilizing the own weight of the PVC pipe 61.

(5) In the existing net field, a metal chain is attached as a weight to the lower end of the lower net 50 in order to deploy the net underwater, but since the PVC pipe 61 also serves as a weight, it is not necessary to attach the metal chain.

The above embodiment may be changed as follows.
○ When the PVC pipe 61 is used as the fishway 60, the number of pipes used and the diameter and length of the PVC pipe 61 are not limited to this embodiment and can be changed.

○ The fish path 60 is not limited to the PVC pipe 61 described in the present embodiment, and may be a pipe body using other resins such as acrylic, polyester, and ABS. Further, in addition to the resin, a metal such as stainless steel, carbon, concrete, or a composite thereof may be used.

In addition, as an existing product that can be used as it is for fishways, there is a transportation pallet used for forklifts. The transport pallet is formed with a fork outlet for a forklift on the side surface, and since this outlet penetrates the opposite side surface, it can be used as a fishway 60. The material of the transportation pallet includes wood, resin, metal, etc., but resin is preferable from the viewpoint of handling and durability.

Further, the fishway 60 is preferable because a material having a specific gravity of more than 1 sinks in water by its own weight, but even if the material has a specific gravity of less than 1, the fishway 60 can be settled by attaching a weight to the fishway 60.

○ The shape of the fishway 60 is not limited to the cylindrical shape described in this embodiment. As shown in FIG. 6a, the shape of the opening 63 may be rectangular, and as shown in FIG. 6b, a plurality of openings 63 (four in the figure) may be present. Further, as shown in FIG. 6c, the fishway 60 may be formed only by a frame and the six surfaces may be open, or the wire mesh may be a cylindrical or polygonal tubular body of the fishway 60 (not shown). The fishway 60 may have an opening 63 that opens across the net, and may have a passage 64 that communicates with the opening 63.

In the configuration shown in FIG. 6c, the opening formed on the side surface also functions as the opening 63 because aquatic organisms can enter and exit from the portion not covered by the lower net 50 when the lower net 50 lands.

○ The shape of the fishway 60 is not limited to the configuration described in this embodiment, and as shown in FIG. 6d, any of the side portion, the upper portion, and the bottom portion may not be formed so as to form a U-shaped cross section. .. Even with such a shape, since the opening 63 has an opening 63 that opens across the net (including the virtual surface) and the opening 63 communicates with the passage 64, the traffic of aquatic organisms that sandwich the lower net 50 Is possible. In the configuration of FIG. 6d, since both end faces and the side surfaces are open, it can be said that there is only one opening 63 as a whole, but there is an opening 63 that opens across the lower net 50, and the opening 63 is provided. It is configured to have a passage 64 communicating with. In addition, although not shown, an H-shaped cross section, a U-shaped cross section, or the like may be used.

○ The position where the fishway 60 is arranged may be changed. Specifically, as shown in FIG. 7a, the fishway 60 may be sandwiched at a position penetrating the lower net 50, and as shown in FIG. 7b, the fishway 60 may be arranged under the lower net 50 by shifting in the length direction. good. Further, the length of the fishway 60 may be short as shown in FIG. 7c, and the fishway 60 may be arranged at a plurality of locations having different heights as shown in FIG. 7d.

As shown in FIG. 7a, when the fishway 60 penetrates the lower net 50, the lower net 50 can be connected underwater by connecting the weight metal chain 54 to the lower end of the lower net 50 with a binding rope (not shown). It can be deployed without sagging.

○ In the above embodiment, an example in which the PVC pipe 61 is used as it is as the fishway 60 has been described, but as shown in FIG. 8a, when the PVC pipe 61 is used as the fishway, holes penetrating inside at the side and bottom surfaces. May also be formed as an opening 63. In this way, not only the opening 63 on the end surface of the PVC pipe 61 but also the opening 63 on the side surface and the bottom surface, so that organisms can invade when the PVC pipe 61 bottoms out. The opening 63 is increased. Even if the opening 63 on the end surface of the PVC pipe 61 is blocked at the time of landing, the organism can enter the passage 64 in the PVC pipe 61 from the opening 63 on the side surface or the bottom surface of the PVC pipe 61, and the organism can enter the passage 64. Makes it easier to come and go across the net.

Further, FIG. 8b is a configuration in which a plurality of PVC pipes 61 shown in FIG. 8a (four in the figure) are connected. In this configuration, since the opening 63 on the side surface of the PVC pipe 61 faces the opening 63 of the adjacent PVC pipe 61, the organism can move across the plurality of PVC pipes 61, and the organism sandwiches the net. It will be easier to come and go.

○ Even when the fishway 60 is difficult to function as a weight in water, for example, when the specific gravity of the fishway 60 is close to water, if the metal chain 54 for weight is connected to the lower end of the lower net 50 in the same manner, the lower net 50 can be placed in water. It can be deployed without sagging.

○ The fishway 60 does not have to be a straight line, but may be a curved line (for example, an arc shape) or a shape in which a plurality of straight lines are combined (for example, a dogleg shape).
○ The fishway 60 may have a shape in which the thickness of the opening 63 or the passage 64 is not constant and changes, specifically, a bellows pipe. However, in order to allow the passage of aquatic organisms through the fishway 60, the area of the narrowest portion of the opening 63 and the passage 64 needs to be larger than the area of the mesh of the net. If there are a plurality of mesh areas for the part where aquatic organisms come and go, the largest mesh area is the target.

○ The length of the fishway 60 is not limited. However, if the cylinder is short, for example, when the opening 63 is on both end faces, the cylinder collapses when the fishway 60 lands, and the opening 63 faces the bottom of the lake, or the lower part is slack. Since the net 50 may block the opening 63 when it covers the fishway 60, it is preferable that the length is such that such a situation does not occur.

○ A canopy may be formed on the opening 63 of the fishway 60. Even when the lower net 50 covers the opening 63 of the fishway 60 when the lower net 50 has landed on the ground, the opening 63 can be prevented from being blocked by the eaves.

○ The fishway 60 is suspended from the lower main rope 20 by a hanging rope 62a, but it is suspended from any of the upper main rope 10, the float 30, the upper net 40, the lower net 50, the weight metal chain 54, and the like. May be good. When the fishway 60 is suspended from the upper net 40, the lower net 50, the weight metal chain 54, etc., the weight of the fishway 60 acts on the upper net 40 or the lower net 50. In order to reduce the weight of the fishway 60 hanging on the net, an auxiliary rope may be connected to the fishway 60 from the upper main rope 10, the lower main rope 20, the float 30, and the like.

○ The sway prevention rope 62b is hung from the lower main rope 20, but it may be hung from a different place as long as the sway of the PVC pipe 61 can be prevented.
○ The net field is not limited to dam lakes, but may be used for rivers, lakes and marshes.

1 ... Aba 10 ... Upper main rope (rope)
20 ... Lower main rope (rope)
30 ... Float 40 ... Upper net (net)
50 ... Lower net (net)
60 ... Fishway 63 ... Opening 64 ... Passage

Claims (5)

A rope spanned over the designated water area and
With multiple floats connected to the same rope,
A net field comprising the rope or a net connected to the float and at least partially located in water.
The net field has a fishway located in the water and has a fishway.
The fishway has an opening that opens across the net and a passage that communicates with the opening under the net.
A net field characterized in that the area of the narrowest portion of the opening and the passage is larger than the area of the mesh of the net. The net field according to claim 1, wherein the fishway is a cylindrical body made of synthetic resin. The net field according to claim 1 or 2, wherein the fishway is suspended from a rope. A rope spanned over the designated water area and
With multiple floats connected to the same rope,
A fishway provided in a net field provided with the rope or a net connected to the float and at least partially located in water.
The fishway is located in the water
The fishway has at least two openings that open across the net and a passage that connects the openings under the net.
A fishway characterized in that the area of the narrowest portion of the opening and the passage is larger than the area of the mesh of the net. The fishway according to claim 4, wherein the fishway is a cylindrical body made of synthetic resin.

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