JP2002206229A - Method for supporting fish way and going upstream or downstream of aquatic life - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive the restoration or the maintenance of the population of wandering-through aquatic life by supporting going-upstream or downstream of the aquatic life. SOLUTION: A fish way installed on the upstream and downstream fall part of a river crossing structure is provided with a staircase-like water passage part, a side wall part rising respectively upward from both right and left sides in the direction of flowing water in the staircase-like water passage part and forming a flow passage together with the staircase-like water passage part. The fish way wherein at least one buffer material is detachably arranged in the staircase-like water passage part is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fishway for assisting aquatic organisms to climb or descend a river, and a method for assisting the same.

[0002]

2. Description of the Related Art Many aquatic organisms inhabiting rivers have "through migratory properties" that move between the sea and rivers in their life history. These migratory aquatic organisms can not breed unless they descend to the sea once in their life history. For example, sweetfish lay eggs in freshwater bodies, hatched larvae flow down to salty estuaries and seas, spend their larval stage in estuaries and seas, grow into juvenile ayu, and then run up the river.

However, at present, many rivers are provided with river crossing structures such as dams, weirs, erosion barriers, head works, etc., whereby the migration path of the aquatic organisms is cut off. A population of migratory aquatic organisms is at risk of decline or extinction.

[0003] Further, among the aquatic organisms, there are species that are important as foods for fish and the like, and these are one of the organisms constituting a food web in rivers and the sea, so that the aquatic organisms do not decline. The extinction has led to changes in the food web and is having a major impact on river and sea ecosystems.

Accordingly, it is an object of the present invention to provide a fishway suitable for assisting the ascent and descent of aquatic organisms, and a method for assisting the restoration and maintenance of a population of migratory aquatic organisms. And to restore or maintain ecosystems in the sea and rivers.

[0005]

Means for Solving the Problems As a result of extensive observations, the present inventors have obtained the following findings on the ecology of aquatic organisms going up and down.

[0006] Aquatic organisms (swimming fish such as sweetfish, benthic fish such as Yoshinobori, and crustaceans) have the property of going upstream toward the upstream against the flowing water (positive running property).

[0007] Swimming fish such as sweetfish fly up and down in places where there is a certain flow velocity and water depth. On the other hand, crustaceans and benthic fish go up and down along the extremely shallow and gentle flow at the shore (when there is an overflow) or at the bottom of the river at the core.

[0008] When the upstream portion has a predetermined inclination angle with respect to the horizontal plane, the upstream and lowering of the aquatic organisms becomes easy.

[0009] The timing of aquatic organisms going up and down is limited seasonally.

[0010] Swimming fish, such as sweetfish, rest at places where the flow is weak and there is a certain depth of water.

The crustaceans approach the weir flow while crawling along the water until immediately before going up. In addition, the crustacean finds a point where a critical flow is approaching from a fast-flowing area to a slow-flowing area, and enters the water from the water's edge.

The present invention, in view of the ecology of aquatic organisms, provides an optimum fishway for ascending fish by swimming and crawling crustaceans and benthic fish. That is, the fishway according to the present invention is a fishway installed at the head of the river crossing structure at the upstream and downstream, and the waterway portion and the water flow direction on the waterway portion are directed upward from both the left and right sides. And a side wall that forms a flow path together with the rising water channel section, and has at least one stagnant portion of the flow and a portion where the flow is fast near the side wall.

The river crossing structure according to the present invention corresponds to a dam, a weir, a sand dam, a head work or the like provided in a river.

The staying portion of the flow is a portion where the flow rate of the water flowing down the fish passage is temporarily reduced and the flow stays.
The fast flowing portion is a portion where the flow velocity of the flow exiting the stagnant portion of the flow is temporarily higher near the side wall of the fishway than near the center.

Further, the fishway according to the present invention is a fishway installed at the head of the river crossing structure at the upstream and downstream of the river crossing structure, and is provided with respect to a stepped channel and a direction in which water flows on the stepped channel. And a side wall that rises upward from both left and right sides to form a flow path together with the step-shaped channel. At least one cushioning material is removably arranged in the step-shaped channel. .

The cushioning material referred to in the present invention is a member having a function of weakening the flow velocity flowing through the flow channel as a whole, and forming a high-flow portion and a low-flow portion (retaining portion) in the flow channel. . That is, by installing the cushioning material, the water flow can be directed to the vicinity of the side wall, so that a relatively fast flow and water depth can be formed in the vicinity of the side wall and a relatively gentle flow is formed in the downstream portion where the cushioning material is disposed. Flow can be formed.

Since the cushioning material is detachably arranged, it is possible to adjust the flow of the fishway so as to be most suitable for the creatures going up in the season by attaching and detaching some or all of the cushioning material. It is.

[0018] At least a part of the cushioning material may be placed on a substantially horizontal portion constituting the stepped channel portion. For example, all of the cushioning material may be placed on a substantially horizontal portion that constitutes the stepped channel portion, or a portion of the cushioning material may be placed and placed on the substantially horizontal portion. The portion of the cushioning material that is not provided may hang down from the substantially horizontal portion to the lower stage of the stairs. Alternatively, the cushioning material may be placed over a plurality of steps. By placing the cushioning material as described above, it is possible to preferably form the distribution of the flow in the channel in the fishway.

[0019] The cushioning material may have a gap so that flowing water passes through the gap. The gap is a hole or gap having a size such that flowing water can pass between the cushioning materials.
Since flowing water can pass through the gap, it is possible to prevent the flow from being disturbed by disposing the buffer material. As an example of the cushioning material, a material having a plurality of pores so that flowing water can pass through the pores may be mentioned.
In another example, the cushioning member includes a plurality of members (for example, two logs) and is arranged such that a gap is formed between these members.

It is preferable that the cushioning member includes a plurality of filling members and a mesh member including the filling members.
The mesh member has a large number of meshes, and is preferably made of a metal such as stainless steel or iron, a synthetic resin such as PE, PP, PET or a fluororesin, a natural resin, a chemical fiber, or a natural fiber such as Manila hemp. Used. The mesh member may be in a sheet shape or a bag shape.

In particular, it is simple and effective to use a stone as the filling member, use a wire mesh as the net-like member, and fill the wire mesh with the stone and bundle the wire mesh to form a cushioning material.

The height of each step in the step-like channel is preferably in the range of 1 cm to 10 cm, particularly 3 cm, from the viewpoint of forming a flow suitable for upstream migration of aquatic organisms.
It is preferably at least 5 cm or less. In addition, the size of the filling member is preferably in the range of 2 cm or more and 8 cm or less, and more preferably in the range of 3 cm or more and 5 cm or less, from the viewpoint of forming a flow suitable for upstream migration of aquatic organisms.

It is preferable that a fixing means for fixing a cushioning material is provided on at least one of the stepped channel portion and the side wall portion. It is particularly preferable that the fixing means is provided near the side wall in the stepped channel. As the fixing means, an engaging portion is provided on at least one of the stepped channel portion and the side wall portion, and an engaged portion is provided on the cushioning material side, and the engaged portion is engaged with the engaging portion so that the buffering portion is provided. The material may be configured to be fixed. For example, a protrusion may be provided in the step-like channel, and one or both ends of the cushioning material may be fixed to the protrusion by hooking, hooking, or the like, or a depression in the step-like channel may be provided. May be provided, and one or both ends of the cushioning material may be hooked and fixed to the protrusion. As another example of the fixing means, a bolt hole may be provided in at least one of the stepped channel portion and the side wall portion, and the cushioning material may be fixed by tightening the bolt.
By releasing the fixing by the fixing means, the cushioning material can be easily detached from the fishway. If a plurality of fixing means are provided, it is possible to attach / detach the cushioning material or change the number / position of the cushioning material to be arranged so that the flow is most suitable for the aquatic organisms going up in the season.

In the above, it is preferable that the water channel portion is inclined at an angle of 5 ° or more and 50 ° or less with respect to a horizontal plane. Further, it is preferable that the waterway portion is inclined at an angle of 6 ° or more and 30 ° or less with respect to a horizontal plane. Further, the waterway part has an angle of 1 to the horizontal plane.
It is preferable that the inclination be made in the range of 0 ° to 23 °. In particular, it is preferable that the water channel part is inclined at an angle of not less than 18 ° and not more than 20 ° with respect to the horizontal plane.

It is preferable that one or both of the side wall portions is inclined at an angle at which the width of the flow channel widens from the water channel portion and which is suitable for upstream or downward movement of aquatic organisms.

One or both of the side walls is
This means that only one of the side wall portions may be inclined at a predetermined angle, or both of the side wall portions may be inclined at a predetermined angle. More specifically, it is preferable that the side wall portion is inclined at an angle of 30 ° or more and 50 ° or less with respect to the stepped channel portion, and it is more preferable that the sidewall portion is inclined at an angle of 45 °. .

In the above, it is preferable that the side wall portion is formed so as to present minute irregularities on the surface. Further, the surface of the side wall has an average surface roughness of 0.1 m.
It is preferably from m to 10 mm, more preferably from 0.2 mm to 5 mm. It is preferable that, for example, concrete, sandpaper, artificial turf, cellular concrete, resin sheet, or the like is laid or adhered to the surface of the side wall portion, so that the surface has a fine unevenness. In particular, it is preferable that the side wall has a surface provided with concrete or sandpaper. When sand paper is used, it is particularly preferable that sand having a particle size of about 0.2 mm is used. By using such a side wall,
Crawling up and down along the shore of the side wall
Descent becomes easy.

The method according to the present invention uses the above fishway
This is a method to assist the ascending and descending of aquatic life.

The aquatic organisms referred to in the present invention include swimming fish such as sweetfish, crustaceans such as shrimp and crab, and benthic fish such as Yoshinobori, eel and goby.

The use of the above fishway facilitates the advancing and descending of aquatic organisms, so that the population of aquatic organisms having migratory properties can be restored or maintained, and the ecosystem in the sea and rivers can be restored or maintained. Maintenance can be achieved.

[0031]

Next, embodiments of the present invention will be described, but the present invention is not limited thereto.

(First Embodiment) FIG. 1 is a perspective view of a fishway according to a first embodiment of the present invention.

In FIG. 1, the fishway 10 includes a stepped channel 1, a side wall 2, a leg 4, a support member 3, and a cushioning material 7.
And a projection 8.

The leg 4 has an inclined surface having an inclination angle α with respect to the horizontal plane, and the stairway channel 1 is attached and fixed to the inclined surface of the leg 4. The support member 3 has a triangular prism shape having a slope inclined at an angle θ,
The side wall 2 is provided to support the leg 4. The side wall portion 2 is connected to the stepped channel 1 via the support member 3.
Are fixed to the legs 4 so as to rise obliquely upward from both sides in the longitudinal direction, and have an inclination angle θ suitable for the ascending and descending of aquatic organisms with respect to the stepped waterway 1. As a result, the flow path formed by the stepped water channel portion 1 and the two side wall portions 2 has a trapezoidal cross section with an open upper side.

The cushioning material 7 is composed of the stone 5 and the wire mesh 6 which is filled and bundled. The cushioning member 7 is placed on a substantially horizontal portion constituting the stepped channel portion 1. Both ends of the cushioning member 7 are fixed to the projections 8 provided in the stepped waterway portion by being attached thereto.

The fishway 10 is installed at the upper and lower heads of the river crossing structure, with the top of the stairs near the top of the river crossing structure and the bottom of the stairs near the bottom of the river crossing structure. You. The water flowing from the upstream area flows down the stepped waterway section 1 or the side wall section 2 of the fishway 10, and flows down to the downstream area while receiving a predetermined flow resistance.

The fishway has a structure using a predetermined step-like waterway portion and a side wall, and a buffer material is provided at a predetermined position (for each step, or 2 to 2 steps).
By arranging every five stages, the flow velocity flowing through the flow path can be reduced as a whole, and a high-flow part and a low-flow part can be appropriately formed in the flow path.

Depending on the arrangement of the cushioning material,
A relatively gentle flow can be formed in the downstream portion where the cushioning material is arranged, and a relatively fast flow and a constant water depth can be formed near the side wall portion where the cushioning material is arranged.

By arranging the cushioning material as described above, it is easy for the swimming fish such as sweetfish to go up and down.

Further, by providing the predetermined side wall, the shore can be widened, and even when the flow rate changes, the flow velocity is moderately reduced, and near the shore, suitable for upstream and descending of crustaceans and benthic fish. Flow rate can be maintained. In addition, when the flow is disturbed by the step-like portions, the surface of the side wall is splashed, and the surface of the side wall is constantly wet, so that crustaceans and benthic fish can crawl safely even if they come out of the water surface. Can be. In addition, since a flow in which air is mixed is formed by the step-like portion, a crustacean or a benthic fish can easily find an entrance into the water by shaking of the water surface due to the influence of the flow and the bubbles. Since the side wall is provided at a predetermined angle, the flow velocity is weakened at the shore, so that the crustaceans can easily crawl along the shore and easily enter the water.

By inclining the side wall by a predetermined angle, birds such as herons, which are predators of aquatic organisms, can be made difficult to catch. Furthermore, because of the step shape, aquatic organisms can enter the dead water area at the corner of each step and rest on the way up and down.

As described above, according to the present invention, in addition to being able to effectively assist the ascending and descending of swimming fish such as ayu, the crawling of benthic fish such as crustaceans and Yoshinobori can be achieved. It is also possible to effectively assist the run-up and descent at the same time. In addition, since the cushioning material is removable, when the swimming fish such as ayu are going up and down, the cushioning material is arranged to assist the fish to go up and down by swimming. It can also assist in ascending and descending by crawling of live fish. On the other hand, at other times, the cushioning material is removed and used mainly to assist in climbing and descending by crawling of crustaceans and benthic fish, thereby preventing deterioration and consumption of the cushioning material.

In FIG. 1, the inclination angle θ is 30 ° or more and 5
It is preferable that the angle be in the range of 0 ° or less. Within this range, the action of decelerating the water flow flowing down in the fishway 10 at the water's edge is high, so that crustaceans can easily crawl at the water's edge and enter the water. In addition, when the angle is set to 50 ° or less, it is easy for the crustaceans to go up and down, and when the angle is set to 30 ° or more, it is difficult for birds such as predators such as herons to stop, so that aquatic organisms may be eaten. Becomes smaller. From the above viewpoint, the inclination angle θ is particularly preferably 45 °.

The angle of inclination of the stepped channel portion 1 with respect to the horizontal plane is preferably in the range of 5 ° to 50 °, more preferably 6 ° to 30 °. By setting the inclination angle at 50 ° or less (more preferably at 30 ° or less), it is easy to swim and descend by swimming of swimming fish such as sweetfish, and climbing by crawling of crustaceans and benthic fish.・ Descent becomes easy. In addition, when the angle is set to 5 ° or more (more preferably, 6 ° or more), aquatic organisms actively run up due to the positive flow property. In particular, the inclination angle is 10 ° or more and 23 ° or less (more preferably 18 °
(20 ° or less), the momentum of the flow is most efficiently weakened, the aquatic organisms are easy to go up, and the flow makes it easier for the crustacean to recognize the entrance of the fishway, making it easier to enter the entrance of the fishway. .

If the riverbed at the head of the river crossing structure is not flat, the inclination angle α of the fishway 10
Does not coincide with the inclination angle formed by the stepped waterway section 1 with respect to the horizontal plane, it is necessary to adjust the inclination angle α in advance so that the inclination angle formed by the stepped waterway section 1 with respect to the horizontal plane has the above-mentioned preferable value. is there.

Further, it is preferable that the surface of the side wall portion 2 is formed so as to exhibit minute irregularities. In this way, by laying a material that makes it easy for the crustaceans to climb on the legs, the crustaceans can easily go up and down.

As a method of forming the surface so as to have a minute unevenness, a mortar is sprayed on the surface of the side wall portion 2, concrete is applied, and then the surface is scratched with a bamboo broom or the like before drying. Rough finishing method, side wall 2
Method of sticking water-resistant sandpaper on the surface of the wall, side wall 2
A method of sticking a surface material made of concrete on the surface of the wall or a method of sticking artificial grass on the surface of the side wall 2 is preferably applied.

(Second Embodiment) FIG. 2 is a perspective view of a fishway according to a second embodiment of the present invention.

The fishway 20 according to the present embodiment has a cushioning material 1
7 is composed of a log 171 and a log 172.
Is different from the embodiment. The protrusion 18 is provided with a projection (not shown) toward the side where the logs 171 and 172 are arranged in FIG.
A concave portion is provided at each end of the log 172 and the log 171 is fixed to the projection 18 by fitting the convex portion and the concave portion.
As shown in FIG. 2, the logs 171 and 172 are fixed to the projections 18 and are placed on a substantially horizontal portion of the stepped channel 11. There is a gap between the log 171 and the log 172.

By arranging the buffer material 17 (the log 171 and the log 172) in this manner, the flow velocity flowing through the fish passage can be reduced as a whole, and a relatively gentle flow ( A stagnant portion) can be formed, and a relatively fast flow and a constant water depth can be formed near the side wall portion where the cushioning material 17 is arranged. Log 171 and Log 172
Since the gap is open between the gap and the gap, flowing water can pass through the gap, and disturbance of the flow due to the arrangement of the cushioning material 17 can be prevented.

[0051]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(Preparation of Fishway) Fishway A A fishway having a stepped channel as shown in FIG. 1 was produced as follows. A wooden material was used for both the stepped channel portion and the side wall portion, and a surface material made of sandpaper having an average surface roughness of 0.2 mm was stuck on the surface of the side wall portion. The inclination angle θ of the side wall is 45 °, the inclination angle α of the stepped channel is 19 ° (the inclination of the stepped channel with respect to the horizontal plane is also 19 °), and the vertical height of the fishway is about 88 cm. The height of each staircase is 4 cm each, and the width of the entire fishway is 1.0 m (the width of the staircase is 60 c.
m), and the length of the fishway was 255.57 m.

Of the substantially horizontal portions (each step portion) constituting the step-like waterway portion (consisting of 22 steps), four portions at the fourth, ninth, fourteenth, and nineteenth stages from the downstream side. A buffer was placed. As the cushioning material, a material obtained by wrapping a stone having a size of about 3 to 4 cm with a wire mesh made of stainless steel was used.

Fishway B The inclination angle α of the stepped channel is 11.3 ° (the inclination angle of the stepped channel with respect to the horizontal plane is also 11.3 °), and the vertical height of the fishway is about 40 cm. The height of the steps was 4 cm each, the width of the entire fishway was 1.5 m (the width of the stepped portion was 80 cm), and the length of the fishway was 2 m.
Of the substantially horizontal portions (each step portion) constituting the step-shaped waterway (consisting of 10 steps), the third and sixth steps from the downstream side
The cushioning material was arranged at three positions on the ninth and ninth stages. Other than that, fishway B was prepared in the same manner as fishway A.

The fishway A and the fishway B are respectively installed on the right bank side of a head work located 3 km upstream from the mouth of the Kawadori River (Yuseura River, Oseto-cho, Nagasaki Prefecture),
A descent experiment was performed.

The experiment was conducted in June 2000 on a 24-hour basis (from 4:00 pm to 4:00 pm on the following day). In order to grasp the ascending and descending status of the test specimens (aquatic organisms), they were recorded by video (infrared video at night), and the number of test specimens (aquatic organisms) climbed up every hour was measured.

As a result of the experiment, in both the fishway A and the fishway B, it was observed that the juvenile Ayu went up and down near the side wall of the channel. In addition, many individuals who entered the dead water area at the corner of the stairs where no cushioning material was placed and took a rest during ascent were observed. In addition to ayu, it was also observed that Kawamutu, Mokuzugani, Yamatonuma shrimp, Mizorenuma shrimp, southern giant shrimp, and Gokurakuhaze go up and down the shore on the side wall of the fishway. The shrimp went up and down exclusively through the splash area at the water's edge. By setting the entrance of the fishway to be near the shore of the riverbank, each individual could easily find the fishway. All individuals that once entered the fishway successfully climbed up.

As described above, in both the fishway A and the fishway B, active advancing and descending of aquatic organisms was observed. Particularly, in the fishway B, a larger number of juvenile ayu came up than the fishway A. Was observed.

[0059]

According to the present invention, the flow velocity flowing through the flow channel can be reduced as a whole, and the high-flow portion and the low-flow portion can be appropriately formed in the flow channel. And so on.

Further, since the cushioning material is detachable, the position and number of the cushioning materials can be easily adjusted according to the season.

Further, aquatic organisms can enter the dead water area at the corner of each step and rest on the way up and down.

Since the cushioning material has a gap, the flow does not scatter.

Further, the side wall allows a wide shore, and the flow velocity is weakened at the shore of the fish passage, so that the crustaceans are easy to crawl along the shore, easily enter the water, and the air mixed flow is reduced. As it is formed, you can easily find the entrance to the water. Further, birds and the like, which are predators of aquatic organisms, are unlikely to stay on the side wall portion, so that the aquatic organisms can safely go up and down.

Thus, it is possible to restore or maintain a population of migratory aquatic organisms and to restore or maintain ecosystems in the sea and rivers.

When the inclination angle of the side wall is set to a predetermined value, the effect is further enhanced.

When the inclination angle of the stepped channel with respect to the horizontal plane is set to a predetermined value, the aquatic organisms can more easily go up and down.

Further, by making the side wall portion a predetermined surface shape or surface material, the crustaceans can easily climb up by hooking their legs, so that the crawling of the crustaceans can more easily go up and down.

Further, by using the fishway of the present invention, it is possible to facilitate the ascending or descending of aquatic organisms and to assist the ascending or descending.

[Brief description of the drawings]

FIG. 1 is a perspective view of a fishway according to a first embodiment.

FIG. 2 is a perspective view of a fishway according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Step-like waterway part 2 Side wall part 3 Support member 4 Leg part 5 Stone 6 Wire mesh 7 Buffer material 8 Projection 10 Fishway

Claims (13)

[Claims] 1. A fishway installed at a head portion of a river crossing structure at the upper and lower sides of a river, wherein the waterway portion and the waterway portion rise upward from both left and right sides with respect to a direction in which water flows on the waterway portion. A fishway having a flow path and a side wall forming a flow path, wherein the fishway has at least one stagnant portion of the flow and a portion where the flow is fast near the side wall. 2. A fishway to be installed at the head of a river crossing structure at the upstream and downstream of the river crossing structure, wherein the waterway flows upwardly from both left and right sides with respect to a direction in which water flows on the stepwise waterway. A fish path, comprising: a side wall that rises and forms a flow path together with the step-like channel; and at least one cushioning material is removably arranged in the step-like channel. 3. The fishway according to claim 2, wherein at least a part of said buffer material is placed on a substantially horizontal portion constituting said stepped channel. 4. The fishway according to claim 2, wherein said cushioning material has a gap, and running water passes through said gap. 5. The cushioning material includes a plurality of filling members, and a mesh member including the filling members.
The fishway according to claim 4. 6. The fishway according to claim 5, wherein said mesh member is made of metal, synthetic resin, natural resin, or synthetic fiber or natural fiber. 7. The fishway according to claim 2, wherein a fixing means for fixing the cushioning material is provided on at least one of the stepped channel portion and the side wall portion. 8. The water channel part has an angle of 5 ° with respect to a horizontal plane.
The fishway according to any one of claims 1 to 7, wherein the fishway is inclined in a range of not less than 50 ° and not more than 50 °. 9. The water channel part has an angle of 6 ° with respect to a horizontal plane.
The fishway according to any one of claims 1 to 7, wherein the fishway is inclined in a range of not less than 30 ° and not more than 30 °. 10. The water channel part has an angle of 1 with respect to a horizontal plane.
An inclination in the range of 0 ° or more and 23 ° or less, wherein
The fishway according to any one of items 7 to 7. 11. The water channel section has an angle of 1 with respect to a horizontal plane.
An inclination in the range of not less than 8 ° and not more than 20 °, wherein
The fishway according to any one of items 7 to 7. 12. One or both of the side wall portions is configured to be inclined at an angle at which the width of the flow channel widens from the water channel portion and which is suitable for advancing or descending of aquatic organisms. Item 12. The fishway according to any one of Items 1 to 11. 13. A method for assisting the ascending or descending of aquatic organisms by using the fishway according to claim 1.