JP2736523B2 - Fish nest block to protect fry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fish nest block for protecting fry, and more particularly to the structure of a fish nest block consisting of a box with a screen.

[0002]

2. Description of the Related Art In Japan, there are many rivers, and population and social assets are concentrated in an alluvial plain formed by the rivers. Therefore, river improvement is indispensable for the purpose of preventing floods and the like. On the other hand, many rivers are relatively close to mountains and have many rapids, so the construction of revetments has shifted from masonry to concrete blocks, concrete framing, retaining walls and solid structures over time.

However, in a revetment structure emphasizing only the flood control function, the river environment is monotonous and fixed.
The living conditions of living things become poor. For example, in the case of cultivation fisheries, fry are grown to some extent in fish ponds and then released into rivers, and then left to natural growth. You have to find a suitable hiding place to protect you. In this regard, there is no longer a habitat for rivers that have only monotonous seawalls on straight river channels. There were inconveniences such as being too large and unsuitable, and those blocks being buried in sediment and becoming useless during floods.

[0004]

SUMMARY OF THE INVENTION The present invention is to provide a fish nest block suitable for hiding a juvenile fish, which eliminates the above-mentioned disadvantages associated with seawall construction, and provides such a fish nest block for seawall protection. The purpose is to provide a method for co-locating.

[0005]

In order to achieve the above object, the fish nest block of the present invention comprises a rectangular parallelepiped box which is arranged at a depth formed on the revetment side of the river, and is provided on the front side of the river (ie, a dike in a levee river). At least a part of the front facing the front surface of the seawater, that is, the surface on which the flowing water flows is referred to as "the river surface." It is formed by providing a plurality of holes for lighting and water distribution on both sides, and forming a number of bars at intervals at which fry can pass at least in a space immediately after the screen arrangement portion in the box. It is.

In a preferred embodiment, the grid constituting the screen is a multiplicity of wedge bars having a wedge-shaped cross section, the wedge bars being arranged with the bottom side of the wedge facing the front. Such a lattice screen structure has a narrow slit shape on the front side of the river, so that the litter is hardly clogged. On the contrary, the litter that is likely to be clogged is washed away by the microvibration of the lattice material and the flow velocity difference between the inside and the outside of the screen.

[0007] In another preferred embodiment, the screen is formed by a staggered lattice arrangement, thereby providing a fish nest block suitable for a hidden place where the inside is hard to see from the outside and the outside is well visible from the inside.

As a method of installing a fish nest block as described above, according to the present invention, first, natural stone is hardened in concrete into a curved concave portion of a river (hereinafter referred to as a "water contact portion") or a scouring area. By creating a canal, a depth is formed near the shore. That is, a waterway having a height lower than a riverbed formed by concrete or the like is referred to as a "headrace", and in the present invention, a boulder is used in a low-water revetment in contact with an upstream portion and a middle and downstream portion of the depth of the headway. A dike and a masonry are provided, and the fish nest block is installed so as to interrupt the masonry. Here, "low-water revetment" refers to the revetment where the flowing water flows when the water is low, and "drainage works" refers to the formation section that regulates the direction of the flowing water and stabilizes the low-water channel. It is.

[0009]

1, 2 and 3 are a plan view, a front view and a side view, respectively, of a fish nest block body according to an embodiment of the present invention. The fish nest block 1 has a frame structure 2 forming a rectangular parallelepiped ridge line by an L-shaped material made of, for example, steel, plastic, or the like.
A box is formed by fixing a plate made of plastic or the like. The upper plate 3, the lower plate 4, and the side plates 5a and 5b located on the upstream side and the downstream side are provided with a plurality of holes 6 for lighting and water distribution, respectively, on the rear side.

In this case, the front plate 7 shown in FIG. 2 has an opening at the right half, and a grid-like screen 8 is provided immediately after this opening at an interval allowing fry to enter and leave. Screen 8
Is an array of preferably steel wedge bars 9 having a wedge-shaped (triangular) cross section as shown in FIG. 1 and the bottom side of which is located in front of the fish nest block 1, i. Preferably, they are arranged in a staggered manner in two front and rear rows, and only a narrow interval is exposed on the front side as shown in FIG. 2, so that the inside of the fish nest block is difficult to see. In order to maintain such an arrangement of the wedge bars 9, support wires 10a, 10b, preferably made of metal, which support the upper and lower ends of the wedge bars near the rear, are fixed by welding or screwing. . The wedge bar 9 and the support wires 10a and 10b can also be formed from other materials having appropriate strength such as plastic.

The above-mentioned upper and lower support wires 10
Punching plates 11a and 11b occupying more than half of the depth from the front to the back of the fish nest block 1 are installed directly above and directly below the mounting positions of the fish nests 1 and 10b, respectively. In this installation, the frame structure 2 is an effective installation or support base. These punching plates themselves have a large number of small holes 12 for passing a round bar thinner than the wedge bar 9 at equal intervals.
In 2, the thin round bar 13 described above is inserted at random, and serves as a reed community on the shore for the fry. In this case, the slit interval of the screen 8 is 5 to 5.
10 mm, the interval between the closest round bars 13 is 10 to 20 m
m, which is a convenient size for fry to escape. Although the round bar 13 is only inserted into the lower punching plate 11b, although not shown in the upper punching plate 11a, it is desirable that the round bar 13 be fixed with a nut or the like after insertion.

A plurality of holes 6 provided on the upper and lower surfaces and both side surfaces
Can also enter and leave, but they can only pass through the space behind the perforated plate and round bar 13 array. In addition, these holes 6 promote outflow of earth and sand as adult fish enter and exit, and the arrangement of the holes 6 on the upper surface in particular can provide lighting and shadow suitable for fry. The body of such a fish nest block 1 can be connected alone or in the flow direction or up and down by bolts or the like depending on the river conditions. In this manner, the fish nest block placed on the river vibrates easily or slightly due to the flow of the river because the wedge bar 9 of the screen 8 is supported only by the support wires 10a and 10b at the upper and lower ends thereof, Alternatively, clogging of garbage is prevented by a difference in speed of water flow between the inside and outside of the screen, and it is also useful for shaking off the matter attached to the screen.

The state where the fish nest block 1 is installed in a river is as follows.
They are shown in plan, front, and side views, respectively, of the river section depicted in FIGS. 4, 5, and 6, respectively.
In FIG. 4, a channel-type depth 15 in which concrete embedded stones are arranged and fixed is formed on the front side of the river near the shore 14 of the river, and between the revetment 16 and the depth 15, a megalithic dike 17 is provided in the upstream. Masonry 18 is formed in the middle and downstream portions, and for example, four fish nest blocks 1a, 1
b, 1c and 1d are installed in series in such a manner as to cut into the masonry 18 and face the depth. Note that 19
Is an inspection stair, and 20 is an upper revetment and a management road.

The reason why such a method of installing a fish nest block is adopted is to construct a headrace channel made of natural stone and concrete in contact with a low water revetment 16 in a curved concave portion of a river, a water contact portion, or a scour area. In this way, the flow is varied to form the above-described depth, and the effect of flowing water in the fish nest block installation area is utilized to maintain the effect of flushing the sediment by the flash. These fish nest blocks 1a-1
d is designed to have a 80% draft at flat water level.
The flow velocity of the headrace changes due to the projection of natural boulders in the dike, and fish nest blocks are located in the gentle basin that occurs immediately downstream of the dike, providing a favorable place for the growth of fry. can do.

[0015]

Since the fish nest block of the present invention is constructed and installed as described above, a wedge bar screen which is convenient for the passage of fry and a round which can be evacuated from a foreign enemy like a reed community. It has a bar arrangement, and is a safe place to stay by appropriate lighting from the ceiling and the formation of shadows.
In addition, as mentioned above, this fish nest block has its own litter removal effect, combined with the sweeping effect of the megalithic dike, and is easy to install, inspect, and repair, so that future flood control and natural environment It is very useful for protection.

[Brief description of the drawings]

FIG. 1 is a partially broken plan view showing an embodiment of a fish nest block of the present invention.

FIG. 2 is a front view of the embodiment of FIG.

FIG. 3 is a partially cutaway side view of the embodiment of FIG.

FIG. 4 is a plan view showing a state of a river in which the fish nest block of FIG. 1 is installed.

FIG. 5 is a front view of the installation location of FIG. 4 as viewed from the river surface side.

FIG. 6 is a side sectional view of FIG. 5 viewed from a downstream side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fish nest block 2 Frame structure 3 Upper surface plate 4 Lower surface plate 5a, 5b Side surface plate 6 hole 7 Front plate 8 Screen 9 Wedge bar 10a, 10b Support wire rod 11a, 11b Punching plate 12 Small hole 13 Round bar 14 Low water bank of river 15 Depth 16 Seawall 17 Megalithic dike 18 Stone masonry 19 Inspection stairs 20 Upper seawall and management road

Claims (4)

(57) [Claims] 1. A rectangular parallelepiped box arranged at a depth formed on the revetment side of a river, wherein at least a part of the front facing the front side of the river is formed as a grid-like screen at an interval through which fry can pass. A plurality of holes for lighting and water distribution are provided on both sides located on the upstream and downstream sides, and a number of bars are provided at intervals at which fry can pass at least in a space immediately after the screen arrangement portion in the box. Fish nest block characterized by having been made. 2. A fish nest block according to claim 1, wherein said screen comprises a plurality of wedge bars having a wedge-shaped cross section, the wedge bars being arranged with the bottom side of the wedge facing the front. . 3. The fish nest block according to claim 1, wherein said screen is formed in a staggered lattice arrangement. 4. In a curved watershed or scour area of a river,
By constructing a headrace channel made of natural stone solidified with concrete, a depth is formed near the shore, and megalithic dikes and masonry are provided on the low-water revetment that respectively contacts the upstream and middle and downstream parts of this depth. The method according to claim 1, wherein the fish nest block is installed in an interrupted arrangement.