JP3303049B2 - Fish run-up system to freshwater reservoir - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for moving fish to a freshwater reservoir, and more particularly to a system for moving fish between a paddy field or a fallow field and an agricultural waterway.

[0002]

2. Description of the Related Art In recent years, a biotope (habiting space for animals and plants) that inhabits a variety of organisms by maintaining and improving a biological conservation function on a freshwater reservoir side such as a paddy field or a fallow rice field, a pond in a water park, etc. Attempts have been made to grow plants. For example, not only large fish such as carp, crucian carp and catfish (approximately several tens centimeters in size) but also small fishes such as medaka and loach (approximately several centimeters in size) are introduced into a paddy field or fallow field. It has been known that the inhabitation of the inhabitants has a certain effect on the purification of water quality. As a result, the range of useful plants that can be cultivated in water-purified rice fields has also been expanding. By the way, in paddy fields or fallow fields, land improvement projects are progressing, and it is not uncommon for the water level difference between the paddy fields or fallow fields and the irrigation canals or drainage channels to be several tens of centimeters to one meter.
There has not been any proposal for a fishway connecting the upstream and downstream water bodies with a head of several tens of centimeters to one meter, and generally, for example, freshwater storage such as a dam to which freshwater is supplied from the upstream side. An ice-harbor type stairway and other fishways are known as connecting between a large dropping water area of several meters to several tens of meters, such as between a pond and a river downstream of the freshwater reservoir.

This fishway is provided at a weir of a river having a large head between the upstream and downstream sides, and as shown in FIGS. 14 and 15, an inclined floor 2 connecting a freshwater reservoir and a river, and this inclined floor 2 A plurality of partition walls 4 are provided in a water passage defined by a side wall 3 provided upright on both sides of the surface 2. The partition wall 4 has an overflow portion 5 formed by cutting out both upper sides, and a latent hole 6 below the overflow portion 5. Since such a fishway has a large head between the freshwater reservoir on the upstream side and the river on the downstream side, a large amount of water must be flowed downstream through the fishway to secure the fishway. For this reason, the flow from the overflow portion (notch portion) 5 almost goes straight and hits the downstream partition wall 4, and changes its direction to the next overflow portion (notch portion) 5. Therefore, a large and considerably strong circulation flow is formed in the pool 7 provided between the partition walls. Therefore, only large fishes that have the power to overcome the strong circulating flow formed in each pool 7 can run upstream.

[0004]

Even if the conventional fishway according to the above configuration is applied to a freshwater reservoir such as a paddy field having a small head-to-downstream head and a drainage channel for agriculture, the freshwater reservoir is located on the freshwater reservoir side. If a large amount of water flows down at the overflow at a high speed, there is a problem that it is difficult to move small fishes to the freshwater reservoir side. Further, if the supply of fresh water to the fresh water reservoir is restricted, there is a problem that the water depth cannot be secured at the overflow portion, or that the fresh water on the fresh water reservoir side flows out from the latent hole 6 to the downstream side. For this reason, there has been a demand for the development of a system for catching fish to a freshwater reservoir suitable for a small-flow water passage having a small head of about several tens of centimeters.
For example, there is a problem that it is difficult to move small fish to the freshwater reservoir between water bodies with small heads, such as between a freshwater reservoir at a higher position such as a paddy field and an agricultural drainage system at a lower position. Was. For this reason, in order to introduce small fish into the freshwater reservoir side of paddy fields, etc., it is necessary to capture the small fish and put them into the freshwater reservoir side. When escaping from the freshwater reservoir side to the lower channel, there is a problem that it does not return to the freshwater reservoir side. For this reason, there was a problem that it was difficult to realize a biotope close to the natural environment on the freshwater reservoir side.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to provide a system for ascending fishes to a freshwater reservoir with a simple configuration, in which small fishes can easily ascend. Is what you do.

[0006]

According to one aspect of the present invention, a system for assembling fish into a freshwater reservoir is provided with a paddy field or fallow field storing fresh water inside a weir, and supplying fresh water to the paddy field or fallow field. Pump that keeps the water level low and the water level difference is several tens of centimeters to one meter below the water level of this paddy field or fallow field.
And a fishway connecting the water channel spanning about Le and the rice fields or fallow field, the fishway, and floor with low a and waterway side of the water level in rice fields or fallow field side paddy or fallow within lower than the water level of the water channel, the A side wall that rises upward from both sides of the floor and forms a water passage between a paddy field or a fallow rice field and a water channel inside, and an upstream side and a downstream side provided in a space defined by the floor and each side wall. And a partition wall on which an overflow section for overflowing water on the upstream side is formed, and the amount of water flowing down the fishway by the pump is reduced to a certain small water amount, and the overflow section of the partition wall is formed. The height of small fishes is set to be able to go up to the water level on the downstream side, and the water level of paddy fields or fallow fields is maintained at a substantially predetermined level, so that fish can go up from the channel side to paddy fields or fallow fields. Made Than it is.

[0007] In the system for catching fish to a freshwater reservoir according to one aspect of the present invention, when freshwater is supplied to a paddy field or a fallow field by a pump and the water level rises, water on the upstream side of the bulkhead of the fishway passes through the overflow section. After that, it flows downstream and flows into the waterway. When the pump raises the water level on the paddy field or fallow rice field side to the upstream and downstream of the bulkhead at the overflow section until it reaches a depth at which small fish can go up, and maintains it at that level.
Since small fish can overcome the flow at the overflow section and jump up or swim up the falling water flow, they can go upstream to the upstream,
Not only large fish, but also small fish can easily go up the overflow area and lay eggs and live on the paddy or fallow fields . This increases the diversity of living organisms that live on the paddy or fallow fields . In addition, also small fish even if paddy
Descends from the fallow rice field side to the waterway side and returns to the paddy field or fallow
Since it is possible to go up to the rice field side, it is possible to maintain the diversity of the organisms that inhabit the rice field or the fallow rice field .

[0008] Further, according to another invention of the present invention, a system for ascending fish to a freshwater reservoir is provided with a paddy field or a fallow field storing fresh water inside a weir, and supplying fresh water to the paddy field or the fallow field to adjust the water level. a pump to keep the water level difference lower than the water level in the paddy or fallow is about 1 m from several tens centimeters
A waterway extending from the paddy field or the fallow rice field to a lower water level than the water level of the paddy field or the fallow rice field and a waterway side being lower than the water level of the waterway; and A side wall that rises upward from both sides to form a water passage between a paddy field or a fallow rice field and a water channel inside, and is provided in a space defined by a floor portion and each side wall, and separates an upstream side and a downstream side. And a partition wall with a pit that allows the water on the upstream side to flow to the downstream side.The volume of water flowing down the fishway by the pump is reduced to a certain level, and small fishes run up the pit. The size is set to be as large as possible, and the water level of the paddy field or the fallow field is maintained such that the submerged hole is submerged below the water surface, and fishes are moved up from the channel to the paddy field or the fallow field.

[0009] Fish into a freshwater reservoir according to another invention of the present invention
In a kind of run-up system,Paddy field or fallow fieldTopumpBy
When fresh water is supplied and the water level rises,
The submerged hole sinks below the surface of the water, and the water upstream of
It flows down from the submerged hole to the downstream side and flows into the water channel.pump
But,Paddy field or fallow fieldThe submerged hole is submerged in the water level
Climb up to level and maintain at that level
And the cave is large enough to allow the flow of small fish to flow up
, So only small fish can go up
And prevent the migration of large fish, so when spawning small fish
Of carnivorous fish to harm fry, larvae and small adult fish
Can be

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall layout view showing a test site provided with a fish run-up system to a freshwater reservoir according to one embodiment of the present invention, and FIG. 2 is used for a fish run-up system according to the above embodiment. FIG.
As shown in FIG. 1, a system for ascending fish to a freshwater reservoir according to the present embodiment includes a freshwater reservoir 12 such as a paddy field or a fallow field that stores freshwater inside a ridgeway (weir) 11.
Drainage channel (water channel) 1 lower than the water level of this freshwater reservoir 12
3 is provided. Water is supplied to the fresh water reservoir 12 from a drain 13 through a pump (fresh water supply means) 14. The pump 14 operates a pump 14 based on a signal from the level sensor (not shown) for detecting the water level of the freshwater reservoir 12 and the level sensor.
Is maintained at a substantially predetermined water level. Reference numeral 15 denotes a wavy plate for partitioning the freshwater reservoir 12 into a predetermined area, reference numeral 16 denotes an observation hut provided on an embankment near the fishway 10, and reference numeral 17 denotes a wavy plate whose lower part is buried in the soil. Reference numeral 15 denotes a water temperature sensor, reference numeral 19 denotes an egg-laying bed, and reference numeral 20 denotes an electric lamp. Also,
The discharge port of the pump 14 is connected to the PVC pipe 8. The other end of the PVC pipe 8 is arranged at a position away from the drain 13 of the freshwater reservoir 12. The PVC pipe 8 supplies the water discharged from the pump 14 to the freshwater reservoir 12 through the opening 8a. Reference numeral 9 denotes a concrete block provided to uniformly flow water supplied from the opening 8a to the freshwater reservoir 12. Reference numeral 14 denotes a water tap, which is connected to a pump station (not shown). The hydrant 14 supplies water to the freshwater reservoir 12 when the pump station operates. The opening of the U-shaped communication pipe 17 is always submerged in water, and if a fine mesh is placed over this opening, fish cannot move to another water area partitioned by the plate 15.

As shown in FIGS. 2 and 3, the fishway 10 according to the present embodiment
A stepped bottom plate 22 that gradually decreases toward the side, and a water passage between the freshwater reservoir 12 and the drainage channel 13 that rises upward from both side portions 22a and 22b of the stepped bottom plate 22 and forms an inside of the inside. Side walls 23a and 23b are provided. Bottom plate 22, the flat portions 21a~21d from freshwater pond 11 side to the drainage channel 13 side (in the present embodiment, step S ₁ is approximately 10 cm) predetermined step S ₁ has sequentially lowered in. Among the flat portion 21a to 21d, the highest flat portion 21a of the fresh water pond 11 side in the position, as lower than the water level LV ₁ freshwater pond 11, also, the flat portion 2
Of 1A～21d, the flat portion 21d of the drainage channel 13 side in the lowest position are provided so as to be lower than the water level LV _n of drainage channel 13. Each flat portions 21a~21d, together provided approximately horizontally, with its length in the flow direction L ₁ is fixed length (in the present embodiment, the length L ₁ is 8
0-100 cm). Side walls 23a, 23b
The spacing between the (in this embodiment, the length W ₁ is 60～80Cm) stepped bottom plate in the width direction of 22 length W ₁ corresponds to.

In the space defined by the bottom plate 22 and the side walls 23a and 23b, as shown in FIGS.
Partition walls 24a to 24e are provided to separate the upstream side and the downstream side from the freshwater reservoir 12 at the upstream side to the drainage path 13 at the downstream side. The partitions 24a and 24e are provided at the upstream end and the downstream end of the bottom plate 22, and at the other partitions 24b to 24e.
“d” is attached along each step of the bottom plate 22. Bulkhead 24a~24e (in this embodiment, approximately the thickness W ₂ is 3 cm, see Fig. 7) a predetermined thickness W ₂ have. Pools 33a to 33d for resting fish are formed between the partitions 24a to 24e, respectively. Overflow part 3
0 denotes the partition walls 24a to 24, as shown in FIGS.
e A constant depth D ₁ from the top (in this embodiment, the depth D
₁ is approximately 15 cm), and is composed of a vertical wall portion 30a and an overflow surface portion 30b formed by cutting out an upper half, and the vertical wall portion 30a and the overflow surface portion 30b are curved surfaces inclined to the downstream side, respectively. (See FIG. 7). The overflow portion 30 is configured to flow water downstream when the water level on the upstream side rises and exceeds the overflow surface portion 30b.

In the partition walls 24a to 24e, latent holes of a predetermined size (in this embodiment, substantially square holes each having a side of 4 to 5 cm) 31a to 31e through which small fish can go up are provided in each of the pools 33a. Each of the partition walls 24a to 24e is pierced at a predetermined position so that the partition walls 24a to 24e are submerged in a state where the water is filled with water. As shown in FIG. 8, the latent holes 31a to 31e are formed as curved surfaces in which the center of the surface 32 forming the hole bulges inward. Septum 24a~24d is (in this embodiment, the height H ₁ is 55Cm～65cm) predetermined height H ₁ has, at the height H ₂ (the present embodiment on the most downstream side of the partition wall 24e, the height H ₂ 45cm~55cm) is lower than the other partition wall 24 a to 24 d.

By the way, the partition walls 24a to 24e are connected to the downstream pools 33a to 33d where the overflow section 30 is full of water.
(In this embodiment, the height H ₃ is approximately 10 cm) of the water level or predetermined height H ₃ relative to the water level LV _n of drainage channel 13 is attached to the bottom plate 22 to be higher. This height H ₃
In addition to the height, large fish can go up, and small fish can go up by jumping or swimming by falling water. The most downstream partition wall 24e
Is overflow section 30 is attached to the bottom plate 22 so as to have the same height or less level with the predetermined height H ₃ relative to the water level LV _n of drainage channel 13. In addition, partition walls 24a to 24
overflow section 30 of the e is the water level of the fresh water pond 12 side in a state where each pool 33a~33d water full of is maintained at a predetermined level LV _1, the small flow rate from the fresh water pond 12 side fishway 10 side ( When 3 to 10 liters / sec) of water is discharged, the water depth in the overflow surface portion 30b is set so that the depth D ₂ that can be small-sized fish will swim upstream by swimming falling water flow. The shape and size of each overflow section 30 and each latent hole 31
Since the shapes and opening areas of a to 31e and the capacities of the pools 33a to 33d formed between the partition walls 24a to 24e are set to be the same, the water depth D ₂ in the overflow section 30 is set.
Is substantially the same for all the partitions 24a to 24e.

That is, the most upstream first partition wall 24a
The upstream water level (freshwater reservoir side water level) is the predetermined water level LV₁ To
And reaches the water depth at the overflow section 30 of the first partition wall 24a.
Is D _Two Then, this water depth D_Two The water volume according to the
Is supplied to the pools 33a-33d of a certain capacity on the
The drained water flows into the overflow section 30 of the fifth partition wall 24e on the most downstream side.
But this depth D_Two And run down to the drain 13 side
Swelling. Water level LV of drain 13_n Is low,
Small fish are upstream from the drainage channel 13 side via the latent hole 31e.
Of the drainage channel 13
Water level LV_n With the overflow surface 30b of the fifth partition 24e.
When the water level difference from the drainage channel 13 is small, the small fish
4e can easily cross the overflow section 30. Also,
Water level LV of drain 13_n Drainage channel 1
The same applies to the bulkhead that separates the water surface of No. 3 from the upstream water area
To facilitate the run-up.

The partition walls 24a to 21e adjacent to each other are provided.
The distance between (pool length) L _2, the side walls 23a, the width W ₁ between 23b, (in the present embodiment, depth D ₃ is more than 30 cm) depth D ₃ pools 33a~33d each pool is determined by the The sizes of 33a to 33d are set such that a sufficient area for resting fish can be secured. The pump 14 has an area of the freshwater reservoir 12, an overflow portion 3 of the partition wall 24a.
The discharge amount is set in advance based on the size of 0 and the size of the latent hole 31a of the partition wall 24a, and the amount of water flowing down the fishway 10 (3
10 to 10 liters / sec). Pump 14 is operated by a controller (not shown) based on a detection signal of the level sensor (not shown) so as to maintain the water level of the fresh water pond 12 to a predetermined level LV _1.

Next, the operation of the fish run-up system to the freshwater reservoir according to the above embodiment will be described. Fresh water is supplied from the drain 13 to the fresh water reservoir 12 via the pump 14, the water level rises, and the most upstream first partition wall 24 a
Of the freshwater in the freshwater reservoir 12
First, it flows out from the latent hole 31a to the downstream side. Freshwater reservoir 1
When the water level of 2 further rises and the water reaches the overflow section 30 of the first partition wall 24a and flows downstream over the overflow surface section 30b, the pools 33a to 33d gradually rise in water level from the downstream side. Rises. Each pool 33a~33d full water, the water level of the fresh water pond 12 reaches a predetermined water level LV _1, when the water level LV ₁ is maintained, fishway 1 from freshwater pond 12 side
Water flows in a predetermined flow rate to 0 side (3-10 l / sec), the water depth at the overflow section 30 of the partition wall 24a is a predetermined water depth D _2. The height of the partition overflow section for the water level of the downstream water becomes predetermined height H _3. This flow rate flows into the first pool 33a on the most upstream side, and the same amount of water sequentially flows into the pools 33b to 33d on the downstream side. Each of the pools 33a to 33d has the same capacity, and the overflow section 30 also has the same water mouth area. Therefore, when the same amount of water flows into each of the pools 33a to 33d, the overflow section of the other partition walls 24b to 24e. 30 has the same water depth D as the first partition wall 24a.
It flows down to the downstream side as ₂ and is drained to the drain 13.

As described above, when the fish go up the fishway 10 from the drain 13, the partition walls 24 a to 24 b separating the upstream and downstream sides.
Overflow section 30 of 4d for downstream water level, since small fish is set to the height H ₃ can be jumping, it is possible to run up the upstream side of the partition wall 24 a to 24 d. Further, since the fresh water pond 12 is maintained at a predetermined level LV _1, a substantially constant low flow rate to the fishway 10 side (from 3 to 10 liters / sec
) Water continues to flow. For this reason, each partition 24b-2
Depth D ₂ at the overflow section 30 of 4e becomes depth that can be small-sized fish will swim upstream by swimming falling water flow, when the fish is runup the fishway 10 from drain passage 13 side, the upstream side from the downstream side water Partition walls 24a to 24d can be moved up.

Since the height H ₃ of the bulkhead overflow and the water depth D ₂ of the overflow relative to the water level in the downstream water area are set so that small fishes can go up, only large fishes can be used. Rather, small fish can easily go up from the waterway side to the freshwater reservoir side, and can lay eggs and live in the freshwater reservoir 12. This will increase the diversity of living organisms that live on the freshwater reservoir side. Further, even if the small fish descend from the freshwater reservoir 12 to the drain 13, they can go up to the freshwater reservoir 12 again, so that the diversity of the organisms living in the freshwater reservoir 12 can be maintained. it can.

Further, since the small fish can go up not only through the overflow section 30 but also through the latent holes 31a to 31e, it becomes easy to go up from the channel to the freshwater reservoir. In addition, since each pool 33a-33d is large enough to make fish easy to rest, and the bottom is formed horizontally,
It is possible to go up over time, making it easy for many kinds of fish to go up.

[0021]

[Example] Next, a run-up test of fish to fallow fields was performed.
The outline of the test, the examination method and the examination result will be described with reference to FIGS. 1 and 9 to 13. FIG. 9 is a schematic diagram of the test site, and the test was performed with the overall arrangement shown in FIG.

(I) In flat rice fields, there are many fishes that have a habit of laying eggs in paddy fields, such as carp, crucian carp, catfish and medaka. However, in the field development, in order to increase the head between the paddy field and the drainage channel,
It is almost impossible for fish to reach the paddy field. Therefore, in this test, a small headway (fishway) was set up in a fallow rice field on the shore of Lake Kasumigaura, and it was investigated whether fish could go up to the fallow rice field. In addition, a survey was also conducted on the water purification capacity in fallow fields.

(II) Outline of the Test Site and Investigation Method As shown in FIGS. 1 and 9, the test site is a 1,100 m ² fallow paddy field located on the outer periphery of the reclaimed land on Lake Kasumigaura. Irrigation channels for paddy fields in the reclaimed land run around the periphery of the reclaimed land,
During the irrigation period, the sluice between Kasumigaura will be opened and the water level of the irrigation canal will be the same as Kasumigaura. During the irrigation period, the water level difference between the irrigation canal and the fallow rice field located outside it is usually 0.3 to 0.
5 m. FIG. 9 schematically shows the flow of water at the test site.

The run-up of fish was observed by attaching an optical sensor to a head work (hereinafter referred to as a fishway) and continuously monitoring with a video camera. The fishway is
The fishway having substantially the same structure as the fishway 10 according to the above-described embodiment, and having the smallest dimension among the dimensions of the fishway was manufactured and used. That is, the fishway 110 used in the experiment is shown in FIG.
As shown in FIG. 0, the flow direction length L ₁₀₁ of each flat portion of the bottom plate 122 is 800 mm, the horizontal length W ₁₀₁ of the partition wall 124, that is, the interval between the side walls 123 a and 123 b is 600 mm, The length W ₁₀₃ in the direction is set to half of the partition wall 124, that is, 300 mm, and the notch depth D ₁₀₁ of the overflow section 130 is set to 150.
mm, the height H ₁₀₃ with respect to the water level on the downstream side of the overflow
It was set as 00 mm. Although a hole was provided, the experiment was performed with the hole closed. The flow rate at the overflow section 130 is about 3 to 10 liter / sec.

(III) Results and discussion (1) Fish run-up The number of run-ups increased immediately after opening the floodgate, and reached a peak two days later. As a result of monitoring, most of the fish that went up were crucian carp, and observed about 1,000 fish going up in 10 days from the opening of the gate. The result is shown in FIG. In addition, run-up of medaka and Yoshinobori were also confirmed in the test site. The crucians that had finished laying eggs descended relatively quickly into the original irrigation canal, while medaka and Yoshinobori remained within the test area. When crucian eggs were placed in a beaker and observed, hatching of about 10% was confirmed. It is presumed that the crucian fry descended into the irrigation channel in mid-June, about one and a half months after spawning. The factor that induces fish to run up to the paddy field is the temperature difference (the temperature of the paddy field drainage is higher than the water temperature of the irrigation canal). Showed a dramatic run-up behavior even at low water temperatures.

(2) Water Purification Ability in Fallow Paddy Field Inflow water from the irrigation canal and outflow water into the irrigation canal were collected about twice a week during the survey period, and analyzed for nitrogen and phosphorus. The results shown in FIG. 13 were obtained. The residence time of the water in the test site was about 3 to 4 hours, but about 50% of both nitrogen and phosphorus were removed. Since the effluent was more transparent than the influent, it is considered that mainly suspended components such as microalgae were removed.

(3) Vegetation in the test site The vegetation in the test site was not managed at all. Seri became the dominant species in June. If useful plants are cultivated in the test area, the effects of biotope, water purification, cultivation of useful plants and three birds with one stone are expected.

In the above embodiment, the overflow section and the latent hole are provided in the partition wall. However, the present invention is not limited to this. Only the overflow section may be provided, or only the latent hole may be provided. Is also good. Even when only the overflow section is provided, it is possible to allow not only the large fish but also the small fish to go upstream. In addition, if only a cave is provided and no overflow section is provided in the partition, only upstream of small fishes is allowed and upstream of large fishes can be prevented. Fish damage can be prevented. Further, the height H ₃ of the bulkhead overflow portion with respect to the downstream water level is set to 100 mm, but is not limited to this height. If the water level difference between the upstream and downstream of the bulkhead can be ensured, the height is set to a lower value. Needless to say, it is good. Further, the partition may be provided so as to be replaceable by sliding up and down, and the fish to be introduced into the freshwater reservoir may be selected according to the timing and purpose depending on the type of the partition. Furthermore, in the above embodiment, the freshwater reservoir is a paddy field or a fallow field, but the present invention is not limited to this.
It is sufficient that the head between the upstream and downstream water bodies is about several tens of centimeters to one meter, and it is needless to say that the present invention can be applied to a pond or aquaculture pond in a hydrophilic park. Further, in the above-described embodiment, a plurality of partitions are provided, but the number is not limited thereto, and a single partition may be provided. Furthermore, in the above-described embodiment, the flat portion on the most downstream side is provided so as to be lower than the water level of the drainage channel, but is provided at substantially the same height as the bottom surface of the drainage channel, and the water level of the drainage channel decreases. Also, small fishes may be allowed to go upstream from the latent hole 31e. Also, the side wall 2
3a and 23b may be formed in a shape drawn by a broken line in FIG. 2 (see reference numeral 223b). Further, in the above embodiment,
The freshwater reservoir is supplied with freshwater by a pump, but the present invention is not limited to this.A river, waterway,
Needless to say, if there is a paddy field or the like, a fresh water supply means such as a pump may not be required. Also, it is of course possible to supply water by a water tap 14a provided in a paddy field. It should be noted that if the amount of water discharged from the fishway, the amount of water supplied to the freshwater reservoir and the amount of water discharged from the fishway substantially match, the water level of the freshwater reservoir will be kept substantially constant.

[0029]

As described above, according to the present invention, a paddy field or fallow field storing fresh water inside a weir, a pump for supplying fresh water to this paddy field or fallow field to maintain a water level, and a paddy field or fallow field Water level difference is several tens of centimeters below water level
And a fishway connecting the paddy field or fallow field with a waterway extending about 1 meter from the waterway, the paddy field or fallow field side is lower than the water level of the paddy field or fallow field and the waterway side is lower than the water level of the channel. A side wall that rises upward from both sides of the floor and forms a water passage between a paddy field or a fallow rice field and a water path inside, and an upstream side provided in a space defined by the floor and each side wall. And a partition wall formed with an overflow portion for separating water from the downstream side and overflowing the water on the upstream side.The amount of water flowing down the fishway by the pump is reduced to a certain small amount, and the overflow of the partition wall is performed. Section is set so that small fish can go up to the water level on the downstream side, and the water level of the paddy field or fallow rice field is maintained at almost the predetermined level, and the fish goes up from the channel side to the paddy field or fallow field side Let By doing so, not only large fish but also small fish can be easily ascended from the waterway to the paddy field or fallow field, improving the biological conservation function in the paddy field or fallow field and inhabiting various biotopes in the biotope. Can be done. In addition, the quality of water can be improved by the inhabitation of various living things, and the natural environment can be improved.

Further, according to the present invention, a paddy field or fallow field storing fresh water inside the weir, a pump for supplying fresh water to the paddy field or fallow field to maintain the water level, and a water level lower than the water level of the paddy field or fallow field Difference from a few tens of centimeters to one meter
And a fishway connecting the water channel spanning about Le and the rice fields or fallow field, the fishway, and floor with low a and waterway side of the water level in rice fields or fallow field side paddy or fallow within lower than the water level of the water channel, the A side wall that rises upward from both sides of the floor and forms a water passage between a paddy field or a fallow rice field and a water channel inside, and an upstream side and a downstream side provided in a space defined by the floor and each side wall. And a partition wall provided with a latent hole through which water on the upstream side flows out to the downstream side, so that the amount of water flowing down the fishway by the pump is reduced to a certain small amount, and the latent hole is formed by a small fish. By setting the size of the paddy field or fallow rice field to be able to go up, maintaining the water level of the paddy field or fallow field below the surface of the water, and moving fish from the channel side to the paddy field or fallow field side. , Small fish Only from the canal side to the paddy or fallow fields, preventing the invasion of large carnivorous fish in the freshwater reservoir, preventing the damage of fry, larvae, and small adult fish by carnivorous fish during the spawning period of small fish. Can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall layout diagram of a test site showing an entire system of fish ascending to a freshwater reservoir according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a fishway used in the fish upstream system of FIG. 1;

FIG. 3 is a partially cutaway perspective view of the fishway of FIG. 2;

FIG. 4 is a front view showing the most upstream partition wall of the fishway of FIG. 2;

FIG. 5 is a front view showing a partition attached to a step of a bottom plate of the fishway of FIG. 2;

FIG. 6 is a front view showing the most downstream partition wall of the fishway of FIG. 2;

FIG. 7 is a partially enlarged cross-sectional view in which a part of an overflow section of a partition wall of the fishway in FIG. 2 is enlarged.

FIG. 8 is a partially enlarged transverse sectional view showing a sectional shape of a latent hole of the fishway of FIG. 2;

FIG. 9 is an explanatory diagram schematically showing a flow of water at a test site.

FIG. 10 is a conceptual diagram of a fishway used for the test.

FIG. 11 is a graph showing the relationship between the number of fish going up and the number of days obtained by the test.

FIG. 12 is a graph showing the relationship between the water temperature difference at the time of a run-up peak and the run-up number during a test.

FIG. 13 is a graph showing a change in water purification in a fish run-up test field during a test.

FIG. 14 is a cross-sectional view of a main part showing a main part of a conventional ice harbor type stepped fishway.

FIG. 15 is a front view of a partition wall of the ice harbor type stepped fishway of FIG. 14;

[Explanation of symbols]

10 fishway 11 footpath (weir) 12 freshwater pond 13 drainage (water channel) 14 Pump (freshwater supply means) 22 stepped bottom plate (floor) 23a, 23b, side walls 24a~24e septum 30 overflow section LV ₁ freshwater pond depth at the height D ₂ overflow of the partition overflow section for the water level H ₃ downstream water level of a predetermined level LV _n drainage

Continuing from the front page Application for Patent Law Article 30, Paragraph 1 applied. Published on April 23, 1998. Published in "Ibaraki Shimbun." Application for Patent Law Article 30 Paragraph 1 applied. Published on April 23, 1998. Published in the "Nikkan Kogyo Shimbun" Applied for the application of Article 30, Paragraph 1 of the Patent Law Published on April 23, 1998 Published in the "Nippon Kogyo Shimbun" Applied for the application of Article 30, Paragraph 1 of the Patent Law April 1998 Published in the Nihon Agricultural Newspaper published on the 23rd. Applied for application of Article 30, Paragraph 1 of the Patent Act. Published on April 23, 1998 Published in the Shinano Mainichi Shimbun. Applied for application of Article 30, Paragraph 1 of the Patent Law Heisei. Published in the Shimono Shimbun published on April 23, 2010 Application for Article 30 Paragraph 1 of the Patent Law is available. Published in the Asahi Shimbun published on April 25, 1998 Application for Article 30 Paragraph 1 in the Patent Law applied. Yes Published on “Weekly Agriculture and Forestry” issued on May 15, 1998. (58) Field surveyed (Int.Cl. ⁷ , DB name) E02B 8/08 A01G 25/00 E01G 16/00

Claims (9)

(57) [Claims] Claims 1. A paddy field or fallow field storing fresh water inside a weir, a pump for supplying fresh water to the paddy field or fallow field to maintain the water level, and a water level lower than the water level of the paddy field or fallow field from several tens of centimeters. A waterway extending for about 1 meter and a fishway connecting the paddy field or the fallow rice field, the fishway having a floor where the paddy field or the fallow field side is lower than the water level of the paddy field or the fallow rice field and the waterway side is lower than the water level of the waterway; A side wall that rises upward from both sides of the floor and forms a water passage between a paddy field or a fallow rice field and a water channel inside, and an upstream side and a downstream side provided in a space defined by the floor and each side wall. And a partition wall formed with an overflow section for overflowing water on the upstream side, and the amount of water flowing down the fishway by the pump is reduced to a certain small amount. The overflow section is set so that small fishes can go up to the water level on the downstream side, and the water level of the paddy field or fallow field is maintained at a substantially predetermined level, and fishes are transferred from the channel side to the paddy field or fallow field side. A system for fish to go up to a freshwater reservoir characterized by going up. 2. A partition having a predetermined size in which a small fish can go upstream is provided at a predetermined position on the partition wall, and until the water level on a paddy field or a fallow field reaches a predetermined level, the latent hole is formed on the water surface. The system according to claim 1, wherein the fish goes down into the freshwater reservoir. 3. The floor of the fishway comprises a stepped bottom plate having a flat portion on the paddy field or fallow rice field side lower than the water level of the paddy field or fallow rice field and a flat portion on the water channel side being lower than the water level of the water channel. 2. The method according to claim 1, wherein the step is provided at both ends of the stepped bottom plate on the upstream and downstream sides and at a step of the stepped bottom plate.
Or a system for fish to run up to a freshwater reservoir according to item 2. 4. The flat portion of the stepped bottom plate is formed substantially horizontally, and the width between the side walls, the interval between the adjacent upstream and downstream partitions, and the water depth of the pool defined between the partitions are defined. 4. The system according to claim 3, wherein the fish is set to a predetermined size so that the large fish can rest. 5. The overflow section is formed by cutting out substantially half of one side of the upper part of the partition wall at a constant depth, and the cut-out surface is formed into a curved surface inclined toward the downstream side. A fish run-up system to a freshwater reservoir as described. 6. The system according to claim 1, wherein the height of the overflow section relative to the downstream water level is set to approximately 0.1 m or less. 7. A paddy field or fallow rice field for storing fresh water inside a weir, a pump for supplying fresh water to this paddy field or fallow rice field to maintain the water level, and a water level lower than the water level of this paddy field or fallow rice field from several tens of centimeters. A waterway extending for about 1 meter and a fishway connecting the paddy field or the fallow rice field, the fishway having a floor where the paddy field or the fallow field side is lower than the water level of the paddy field or the fallow rice field and the waterway side is lower than the water level of the waterway; A side wall that rises upward from both sides of the floor and forms a water passage between a paddy field or a fallow rice field and a water channel inside, and an upstream side and a downstream side provided in a space defined by the floor and each side wall. And a partition wall provided with a latent hole that allows the upstream water to flow to the downstream side while separating from the water side. The diving hole is set to the size that small fish can go up, and the water level of the paddy field or fallow rice field is maintained under the water surface, and the fish goes up from the channel side to the paddy field or fallow field. A fish run-up system to a freshwater reservoir. 8. The floor of the fishway is constituted by a stepped bottom plate having a flat portion on the paddy or fallow rice field side lower than the water level of the paddy field or fallow rice field and a flat portion on the water channel side being lower than the water level of the water channel. The system according to claim 7, wherein the step is provided along both ends in the flow direction of the stepped bottom plate and the stepped portion of the stepped bottom plate. 9. The latent hole of the partition wall is formed in a substantially square shape having a side of 4 to 5 cm, and the surface forming the latent hole is formed as a curved surface whose center bulges inward. Fish run-up system to a freshwater reservoir in Japan.