JP3769702B2 - Fishway - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fishway in a river structure, a construction method for the fishway, and a cage structure used in this method.
[0002]
[Prior art]
Conventionally, rivers have been provided with various types of river crossing structures (floor fixing, flooring, dam, drop work, etc.) depending on the purpose and scale. It can interfere with the ups and downs of fish and other aquatic animals and can adversely affect ecosystems. For this reason, in recent years, a fishway is often attached to facilities that need to be able to catch fish in rivers and the like.
[0003]
For fishway, a wide variety of technologies have been proposed and put into practical use.
A) A method of building a formwork on a river crossing work, placing concrete inside of it, and forming a passage surrounded by a concrete partition wall (on-site casting method),
B) A method for creating an environment in which fish etc. can easily go up, for example, by arranging concrete blocks (fishway blocks) molded into a predetermined shape regularly to alleviate the slope of the riverbed or reduce the flow velocity of the river Gazette 1, 2),
C) By preparing multiple pseudo-rock units, each of which has a different shape, imitating natural stones or rocks using special techniques, and arranging them appropriately on the downstream side of the dam of the river crossing work The so-called pseudo rock unit construction method for constructing a fishway (for example, Patent Publications 3 and 4) can be broadly classified.
[0004]
An example of a structure in which overflow walls (partition walls) are provided in the transverse direction and a notch is provided in the vicinity of one side wall to allow overflow is shown (Patent Publication 5), but the rising angle of the overflow wall is steep. When the flow rate increased, it became a separated flow, which made it difficult for fish to move.
[0005]
[Patent Publication 1]
Japanese Patent Laid-Open No. 2001-81765, (FIG. 6)
[Patent Publication 2]
JP-A-8-120655, (FIG. 1)
[Patent Publication 3]
JP 2002-69991 A (FIG. 7)
[Patent Publication 4]
JP-A-9-279552, (FIG. 7)
[Patent Publication 5]
JP-A-10-25730, (Claim 5, FIGS. 3 and 5)
[0006]
[Problems to be solved by the invention]
However, even if the fishway is constructed by the conventional construction methods a) to c) above, regardless of the form or shape (stepped fishway (Y), fan-shaped fishway (Z), etc.), it is located downstream of the fishway. Nakasu X is created (see Fig. 9), and in order to reduce the cross section of the river, for example, if the water is increased, the flow of water changes in the direction of the river and the revetment collapses due to direct hitting of the revetment slope. Is not preferable from the viewpoint of flood control. However, in the past, it was only recognized that such Nakasu X was an inevitable phenomenon caused by a natural phenomenon, and development of a fishway that could prevent the occurrence of Nakasu X was halfway.
[0007]
The present invention has been made in view of the above circumstances, and its purpose is to cause disturbance due to partial deceleration in the overall flow velocity when passing through a river crossing structure at a constant flow velocity during flooding. Therefore, it is difficult to generate Nakasu in the downstream area of the fishway, and it is an object of the present invention to provide a fishway and a method for constructing the fishway that can easily move fish and other seafood up and down.
[0008]
Another object of the present invention is to provide a trough-like structure that can be easily retrofitted by an existing drop work or the like, and that can form a fishway that allows seafood to run up very easily.
[0009]
[Means for Solving the Problems]
The means adopted by the present invention to solve the above problems is that the invention of claim 1 is provided in a river structure that forms a stepped portion in a river or the like, and is used as a transferable facility for fish or the like. A fishway in a river structure that is installed by connecting a place side and a low side, and has an opening in which the upper part of the opening is formed in a curved shape on the side surface of the fishway, part or all of it The gist of the above is arranged on the wall surface portion on the downstream side of the river structure and fixed integrally therewith.
[0010]
The invention of claim 2 is provided in a river structure having a step which forms a head of upstream and downstream, and is installed as a fish movable facility by connecting the high side and the low side of a step part such as a river. A corrugated structure used for constructing a fishway, wherein the corrugated structure is rectangular, U-shaped or C-shaped in cross section, and the upper part of the opening is formed in a curved shape on the side surface side. And has an irregular surface on the inner surface.
The contact with the downstream side of the wall of the river structures or part of its or all disposed within the downstream side of the wall surface of the river structures, what is integrally fixed, and its gist.
[0011]
The invention according to claim 3 is the saddle-shaped structure according to claim 2 , wherein the water-based uneven portion formed on the inner surface of the river structure is further formed with an aqueous uneven portion, The gist.
[0012]
A fourth aspect of the present invention is a fishway in a river structure characterized by placing and fixing the cage-like structure according to any one of claims 1 to 3 on a wall surface on the downstream side of the river structure. the construction methods, the gist of it.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail on the basis of specific examples shown in the drawings. However, this is a representative example, and unless the gist of the present invention is exceeded, the present invention will be described with reference to the following examples. The invention is not limited.
[0014]
First, a typical embodiment of the fishway 10 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view schematically showing the fishway 10, and FIG. 2 is a cutaway perspective view schematically showing the fishway 10. 3 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 4 is a cross-sectional view taken along line BB in FIG. FIG. 5 is a cross-sectional view taken along the line CC in FIG. 1 and corresponds to a front view seen from the downstream side.
[0015]
In this figure, this fishway 10 has a saddle-like structure 11 that forms an upstream / downstream drop in a stepped portion such as a river, with an opening 12 opening on the wall surface downstream of the river structure 13 and a gradient of 1 : It arrange | positions so that it may become a ratio of 20-1: 5, and is being fixed integrally with the river structure 13 by placing concrete, for example.
[0016]
For example, if a screen 20 typified by grating is provided so as to cover both the uppermost portion of the fishway 10 and the water conduit provided in the river structure 13, it is possible to prevent the inflow of earth and sand and the prevention of predation of wild birds and the like. Since an effect is acquired, it is preferable.
[0017]
The bowl-shaped structure 11 is made of a steel material having an opening 12 bent so that the cross-sectional shape is rectangular, U-shaped or C-shaped, and a recess 14 is formed in the inside thereof. Further, a water control uneven portion 14a is formed on the inner surface. However, it is also possible to form a water control uneven part by disposing natural stone or pseudo stone in the recess 14.
[0018]
In addition, a deceleration effect can be obtained by both the water control uneven portion 14b and the water control uneven portion 14b in which a finer water control uneven portion 14b is formed on the surface of the water control uneven portion 14a.
[0019]
The lower part 12a of the opening 12 of the saddle-shaped structure 11 protrudes downstream from the upper part 12b of the opening 12, and the entire opening 12 side is installed and fixed in a state of slightly protruding from the river structure 13. Yes. However, all the saddle-like structures 11 are installed inside the river structure 13 and are integrally formed so that the opening surface of the saddle-like structure 11 is flush with the downstream wall of the river structure 13. It does not matter. It can also be installed in contact with the downstream wall of the river structure.
[0020]
Further, the saddle-like structure 11 is arranged along the wall surface on the downstream side of the existing river crossing structure 13 ', and is fixed integrally with the river structure 13' by placing concrete, for example, so-called "retrofit" It can also be constructed as a fishway (see FIG. 6).
[0021]
Furthermore, the plurality of relatively short bowl-shaped structures 11 ′ may be transported to a construction site, and the bowl-shaped structures 11 may be formed by welding and connecting them at the construction site (see FIG. 7). ).
[0022]
Here, the technical contents of the “saddle-like structure” according to the invention of claim 2 are as follows: a relatively long saddle-like structure 11 and a relatively short saddle-like structure used for constituting the saddle-like structure 11. It is defined to mean both of the body 11 '.
[0023]
When the river structure 13 is long in the crossing direction of the river, it is preferable to install the plurality of eaves-like structures 11 at an appropriate interval since a plurality of fishways can be installed in the river structure 13.
[0024]
Although the relatively short bowl-shaped structure 11 ′ requires a so-called joining process of being welded or bolted in the field, it can be mass-produced, is easy to transport and move, and has excellent handleability. It is preferable in that the reduction can be achieved.
[0025]
When the fish-like structure 11 is configured as a fishway inside the river structure 13 as described above, for example, a water flow that flows over the river structure 13 is guided into the recess 14, and then a part of the water flow is provided below the recess 12. It can be moved over the portion 12a and dropped, and it is easy to pass not only fishes, but also water insects such as moths and turtles.
[0026]
In addition, it is preferable that the upper part of the opening of the river structure is formed in a curved shape because the water flow falling from above can be reliably introduced into the recess 14.
[0027]
That is, unlike a conventional fishway that is installed in a shape that protrudes more downstream than the cross-sectional shape of the river structure 13, the cross-section of the river crossing is constant, and the flow of the flood that passes through it is a heterogeneous shape of the fishway As a result of the structure being changed, the water flow is not decelerated and the flow direction is not changed.
[0028]
Next, as schematically shown in FIG. 8, the fishway 30 of the second embodiment is formed by stacking a plurality of the fishways 10 of the first embodiment so as to be separated from each other in the vertical direction. That is, except that the water overflowing from the opening of the fishway (rooster-like structure) 10 located above flows into the recesses of the fishway (rooster-like structure) 10 located below it. The configuration is substantially the same as the fishway 10 of the first embodiment.
[0029]
Therefore, in addition to the effect obtained by the fishway of the first embodiment, a plurality of fishways can be installed in the river structure 13, and the action and effect that the fishery and other seafood can be moved up and down more easily. can get.
[0030]
【The invention's effect】
As described above, according to the fishway of the present invention, when a river during flooding flows in a constant speed involving sediment and the like that have flowed together in the river width, when passing through a river crossing structure, the structure of a heterogeneous shape such as a fishway Even if it flows down a certain point, the flow of water slows down (in other words, due to the decrease in energy of the earth and sand that has been swept up until then), and the sediment can sink without being swept away. Absent. In other words, unlike a conventional fishway that protrudes greatly toward the downstream side of the cross section of the river slice, there is no formation of a Nakasu on the downstream side of the fishway, and it is also possible to construct the fishway with a so-called “retrofitting” It is possible to obtain exceptionally effective effects with excellent effectiveness.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing a fishway according to a first embodiment of the present invention. The white arrow in the figure indicates the direction of water flow.
FIG. 2 is a fragmentary perspective view schematically showing the same fishway.
FIG. 3 is a cross-sectional view taken along the line AA of FIG.
4 is a cross-sectional view taken along the line BB in FIG. 1. FIG. The white arrow in the figure indicates the direction of water flow.
FIG. 5 is a cross-sectional view taken along the line CC in FIG. 1;
FIG. 6 is a cross-sectional view schematically showing a fishway integrated with a river structure by so-called “retrofitting” a saddle-like structure along a downstream wall surface side of an existing river crossing structure. is there.
FIG. 7 is a perspective view schematically showing a cage structure (fishway) 11 configured by connecting a plurality of relatively short cage structures.
FIG. 7 is a perspective view schematically showing a fishway as a second embodiment of the present invention. FIG. 9 is a plan view schematically showing a relationship between a conventional fishway and Nakasu. . 9A is a terraced type fishway, and FIG. 9B is a fan-shaped fishway. In the figure, white arrows indicate the direction of water flow.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Fishway of 1st Example 11 ... Coral-like structure 11 '... Short coral-like structure 12 ... Opening 12a ... Opening 13 ... River structure 13' ... Existing river structure 14 ... Recessed part 14a ... Lower part 14b ... Upper part 15 ... River structure 20 ... Screen 30 ... Fishway X of the second embodiment X ... Nakasu Y ... Stepped fishway Z ... Fan-shaped fishway

Claims (4)

It is provided in a river structure that forms a step in a river, and is a fishway in a river structure that is installed by connecting the high side and low side of the step as a transferable facility for fish and the like. ,
An upper portion of the opening has a curved surface formed on the side surface of the fishway , and a part or all of the opening is disposed on the downstream wall surface of the river structure and is integrally fixed. A fishway in the river structure. To construct a fishway that is installed in a river structure with a step that forms a head of upstream and downstream, and is connected to the high and low sides of a step such as a river as a movable facility for fish A saddle-like structure used,
The saddle-like structure has a rectangular, U-shaped or C-shaped cross section, and has an opening in which the upper part of the opening is formed in a curved shape on the side surface, and a water control uneven part is formed on the inner surface. ,
In contact with the downstream side of the wall surface of the river structures or part of its or all disposed within the downstream side of the wall surface of the river structures, trough-like structure, characterized in that it is integrally fixed . The saddle-shaped structure according to claim 2 , wherein in the saddle-shaped structure, a water-based uneven portion is further formed on the surface of the aqueous uneven portion formed on the inner surface of the river structure. . The construction method of the fishway in a river structure characterized by arranging the anchor-shaped structure in any one of Claims 1-3 on the wall surface side of the downstream of the said river structure , and fixing .

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