JPH0414509A - Device for adjusting water level of fishway - Google Patents

Abstract

PURPOSE:To easily establish the overflowing water level of the partition wall of a fishway by providing the first side wall between a water level adjusting partition wall and protruding section for producing smooth flows and an inclined water-flow leading partition wall provided with a water passing opening at the lower section on the upstream side between the leading edge side of an inner partition wall and an outer partition wall. CONSTITUTION:A water flow from an intake M flows into a pre-stage pool 10A over the first partition wall 8 while the flow forms an eddy current behind a protruding section 3A at the leading edge of an outer partition wall 3 and reducing the flowing speed and forms a water flow turning area Q adjacent to the eddy current forming area P on the downstream side. The water flowing into the pool A produces an area R where the water flow turns to the upstream side at the bottom section between an inclined water flow leading partition wall 11 and water level adjusting partition wall 7 and is separated into an overflow which flows over the wall 7 and a water flow flowing into a post-stage pool 10B through a water passing port 12. The water flow flowing into the pool 10B further reduces the flowing speed due to the action of a slow speed area S and is led to a fishway pool 13 after flowing over the second partition wall 9. Therefore, a flow speed which allows ayus to go upstream can be obtained with a simple fixed structure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water level adjustment device for a fishway installed near a water intake weir or the like.

(Conventional technology) The mainstream construction style for fishways in Japan is stepped fishways.

Although this type is highly effective in controlling the water force within the fishway, it is important to adjust the water level because fluctuations in the water level overflowing the fishway bulkhead are directly related to the overflow velocity and affect fish migration.

A characteristic of Japan's rivers is that their flow rates fluctuate widely, and this tendency is stronger in small rivers.
Adjusting the water level that overflows the bulkhead is an issue.

The water level adjustment method for stair-type fishways installed in small rivers has traditionally been a corner-drop method at the top of the fishway. The corner dropping method, which adjusts the flow rate by piling up square timbers at the inlet of the fishway, is difficult to manage in small and medium-sized rivers in Japan, which tend to fluctuate frequently over short days, and is difficult to manage when the flow rate suddenly increases. It's dangerous.

(Problem to be solved by the invention) It is estimated that about 70% of fishways in Japan are for sweetfish, and about 30% are for salmon and trout. It is also possible for salmon and trout to migrate upstream as long as the swimming capacity is not exceeded.

In addition, since sweetfish during the upstream period have a strong tendency to swim on the bottom layer of shallow waters and go upstream against the water current, it is preferable that the water flow be such that a plunging flow is formed at each stage (pool). .

Therefore, in the state of a submerged flow formed by a falling flow from the top of the bed, the maximum flow velocity Vpm at the top of the bed is approximately Vpm = 2gh/3 (h = overflow water depth, g = acceleration of gravity), and the maximum It can be seen that the flow velocity is determined by the overflow depth. Judging from the swimming ability of sweetfish, the appropriate overflow speed of the stepped fishway is in the range of 90 to 120 cm/s, and therefore the overflow water depth must be maintained in the range of 12.4 to 22 cm.

The period when sweetfish migrate upstream using fish ladders (March to August) is a time when the river flow rate fluctuates greatly, and assuming that the overflow water depth in the entire middle layer fluctuates between 10 and 50 cm, the maximum overflow velocity is It can reach 81 to 181 cm/s.

There has been a desire for a water level adjustment device that can respond to such river flow rate fluctuations and suppress the flow velocity of the fishway to a range that allows sweetfish to swim upstream.

(Structure) The present invention is a device connected to the uppermost stage of a stair-type fishway and an overflow channel installed in parallel thereto, which comprises an outer bulkhead connected to an outer wall of the fishway and having a protrusion for generating a vortex at its tip, and a fishway. The projecting wall is connected to the inner partition wall that partitions the overflow channel and has an inner partition wall having a shorter length than the outer partition wall, and a protruding wall that blocks the river flow with a water intake interval between the inner partition wall and the protruding end portion of the outer partition wall. , a water level adjusting partition is connected and formed between the tip of the inner partition wall and the protruding wall, and a first partition wall provided between the base of the vortex generation protrusion of the outer partition wall and the water level adjusting partition, and the fishway. a second partition wall provided between the connecting portions of the partition wall, and a water flow guiding inclined partition wall provided between the tip side of the inner partition wall and the outer partition wall and having a water passage opening at the lower part of the upstream side; A desired overflow depth of the fishway partition can be obtained by the difference between the height of the water level adjusting partition and the heights of the first and second partitions.

In the above device, the height h of the first partition wall and the second partition wall are the same, and the height of the water level adjustment partition wall is set higher by a desired overflow water depth, for example, 15 cm.

Further, the water flow guiding inclined partition wall is set at an angle of about 30° from the outer partition wall in the water flow direction, and the height h of the water passage opening provided on the upstream side of the partition wall is the same as that of the first and second partition walls. The width W is preferably 1/2 between the inner and outer partition walls.

(Embodiment) The figure shows an embodiment of the device of the present invention, in which 1 is a water level adjustment device connected to the upstream side of the fishway. 2 is a protruding wall provided on the upstream side of the river, and has a height that the water flow cannot exceed.

3 is an outer partition wall, 3A is a vortex generation protrusion at the tip, 4 is an inner partition wall, and 5 is a side wall of the overflow channel 6.

Reference numeral 7 denotes a water level adjusting partition wall extending upstream of the inner partition wall 4 and connected to the protruding wall, and is set higher than the partition walls 8.9 by a desired overflow water depth (for example, 15 cm).

8 is a first partition installed between the inner and outer partitions, and 50 to
The height is set to about 60cm.

A second partition wall 9 is set at the same height as the first partition wall, and forms a water level adjustment pool 10 between the second partition wall and the first partition wall. 9A is a sinkhole, 13 is a fishway pool, and 11 is a water flow guiding inclined partition wall that divides the adjustment pool 10 into an area ratio of about 6=4, with a distance of about 30 from the outer partition wall 3 to the inner partition wall 4.
It is erected at an angle of inclination of .degree., and a water inlet 12 is opened in the lower half of the upstream side.

The above device is installed as shown in FIG. 5, for example.

20 is a river, 21 is a dam, 22 is a bank, 23 is a width of 2
It is a fish ladder of m.

(Function) In the above device, the water flow from the river flows in from the water intake port M, forms a vortex on the back side of the tip protrusion 3A of the outer partition wall, and passes over the first partition wall to the adjustment boule 1 while the flow velocity is weakened.
0 flows into the pre-boole 10A. At that time, the vortex forming area P
A water flow diversion area Q is generated adjacent to the downstream side of the area.

A part of the water flow from the water intake overflows into the overflow channel 6 over the water level adjustment partition 7 which is 15 cm higher than the first partition, and the average water depth above the top of the second partition is maintained at about 15 cm.

The inflow water in the front pool creates an upward diversion area R at the bottom between the water flow guiding inclined partition wall 11 and the water level adjustment partition wall 7, overflows over the water level adjustment partition wall 7 and passes through the water inlet 12 to the rear stage boule IOB. Divides into incoming water streams. Here, the flow velocity is further weakened by the action of the slow flow area S, and the second partition wall 9
It overflows beyond the river and is introduced into fishway Boul 13.

Needless to say, the water depth on the bulkheads separating each boule of the fishway is maintained at the same level, so that the sweetfish can easily swim upstream through the fishway and finally swim into the river 20 from the water intake M.

The graph in Figure 6 is the result of measuring the water depth at the top of the center of the second barrier when the external water depth varied between 10 and 50 cm in the 115 model test equipment, and the water level adjustment effect is clear. It is clear that a flow velocity that does not impede the upstream migration of sweetfish is guaranteed.

(Effects) As described above, the device of the present invention can obtain the desired water level over the fishway bulkhead with a simple fixed structure and does not require adjustment work, so management is practically unnecessary and it is extremely economical.
It is also extremely useful in river management for the purpose of nature conservation.

[Brief explanation of drawings]

FIG. 1 is a plan view of the device of the present invention, FIG. 2 is a sectional view taken along line A-A,
FIG. 3 is a sectional view taken along the line CC, FIG. 4 is a sectional view taken along the line CC, FIG. 5 is a partial plan view showing an example of application of the device, and FIG. 6 is a grab showing the water level adjustment effect. Symbol description 2 is a protruding wall, 3 is an outer partition, 4 is an inner partition, 6 is an overflow channel, 7 is a water level adjustment partition, 8 is a first partition, 9 is a second partition,
10 is an adjustment boule, 11 is a water flow slope partition, 12 is a water inlet

Claims (1)

[Claims] A device connected to the top stage of a stair-type fishway and an overflow channel installed in parallel thereto, which partitions the fishway and the overflow channel from an outer bulkhead that is connected to the outer wall of the fishway and has a protrusion for generating a vortex at its tip. an inner partition wall that is connected to the inner wall and has a shorter length than the outer partition wall, and a protruding wall that blocks the river flow with a water intake interval between the inner partition wall and the tip protrusion of the outer partition wall; A water level adjusting partition is formed in a continuous manner between a partition tip and the protruding wall, and the fishway is connected to a first partition provided between the base of the vortex generating protrusion of the outer partition and the water level adjusting partition. The water level adjusting partition comprises a second partition provided between the parts, and a water flow guiding inclined partition provided between the tip of the inner partition and the outer partition and having a water passage opening at the lower part on the upstream side. A water level adjustment device for a fishway, wherein the height of the first partition wall and the second partition wall are set to a height that allows a desired overflow water depth to be obtained.