JPH0578290B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for blocking fish from swimming into a prohibited area in water.

[Conventional technology]

Traditionally, in hydroelectric power plants where the flow of a river is blocked by a dam and the dammed water is taken in through the water intake, if fish invade the water intake, the water intake line becomes clogged, causing damage to various parts of the hydropower plant. There is a risk that this could lead to abnormalities in the hydroelectric power plant equipment, causing all functions to stop.Furthermore, fish that have invaded the equipment will be released as dead fish in the drainage water, which raises the issue of fishery compensation for river fish such as sweetfish. As a method to prevent fish from entering the water intake of such hydropower facilities, a net is placed near the water intake, and the net prevents fish from entering the vicinity of the water intake, which is a prohibited area. It is common practice to prevent fish from entering.

However, in this case, a very fine-mesh net is required, and while using such a fine-mesh net is highly effective in preventing fish from entering,
Clogging with debris and dead leaves is likely to occur, leading to a decrease in water intake, so when such clogging occurs, debris is removed using semi-automatic garbage removal equipment or manually, which is extremely time-consuming. The drawback is that maintenance and inspection of the net requires a great deal of cost and effort.

Therefore, the applicant has proposed the following blocking method.

That is, a plurality of electrode rows are arranged in parallel near a prohibited area underwater, and a voltage is applied to each electrode row to form an electric screen with a predetermined electric field strength between each electrode row. The aim is to prevent swimming in prohibited areas.

[Problem to be solved by the invention]

However, in this case, even with the same electric field strength, the electrical stimulation received by the fish differs depending on the fish's body length.
Moreover, in places where there is water flow at a predetermined velocity, such as at the water intake of a hydroelectric power plant, the electrical stimulation received by fish differs depending on the velocity of the water flow, so it is appropriate to set conditions according to the flow velocity, etc. Otherwise, there will be a problem that the electrical stimulation will be too strong and the fish will die, or conversely the electrical stimulation will be too weak and it will not be possible to stop the fish from swimming.

Therefore, the present invention has been made with the above points in mind,
The velocity of water flow in the direction of the prohibited area is 0.1 to 1 [m/m/
sec], the purpose is to be able to reliably block the swimming of fish targeted for blocking.

[Means to solve the problem]

Next, means for achieving the above object will be explained using FIG. 1 corresponding to an embodiment.

That is, two electrode rows 1a, 1b are arranged in parallel in water, and a voltage is applied to both the electrode rows 1a, 1b to form an electric screen 5 with a predetermined electric field strength between the electrode rows 1a, 1b. In the method for blocking fish from swimming in the prohibited area using the electric screen, the present invention provides the following features:
[m/sec], the electric screen 5
The product of the electric field strength and the body length of the fish to be blocked is set to be 1 or more and 2.5 or less.

[Effect]

Therefore, according to the present invention, both electrode arrays 1a,
As a parameter for determining the electric field strength of the electric screen 5 between 1b, the product of the electric field strength [V/cm] and the body length [cm] of the fish to be blocked is introduced,
The velocity of water flow in the direction of the prohibited area is 0.1 to 1 [m/m/
sec], an electric screen 5 is formed in which the above-mentioned product is 1 or more and 2.5 or less, and it becomes possible to give electrical stimulation to fish such as sweetfish to the extent that they can take repellent behavior, and This will ensure that swimming is blocked and fish such as sweetfish are prevented from entering the restricted area.

〔Example〕

Next, the present invention will be described in detail with reference to drawings showing one embodiment thereof.

In FIG. 1, 1a and 1b are two electrode rows arranged in parallel in the water near the water intake of a hydroelectric power plant, which is a prohibited area, and each has a plurality of rod-shaped conductive electrodes 2a and 2b of equal size. The conductive electrodes 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, 2a, and are arranged at a spacing, respectively, and are formed at intervals.
2b are electrically connected by connecting bodies 3a and 3b.

Reference numeral 4 denotes a power source for generating an electric screen, and the power source 4 applies, for example, a DC voltage between the two electrode rows 1a and 1b, thereby forming an electric screen 5 with a predetermined electric field strength between the two electrode rows 1a and 1b.

At this time, the water flow at the water intake of the hydroelectric power plant is directed toward the inside of the water intake, in a direction where entry is prohibited, as shown by the arrow in Figure 2, and the flow velocity is 0.1~
1 [m/sec].

By the way, as shown above, the flow rate of the water flow is 0.1 to 1
[m/sec], select sweetfish as the fish to be intercepted, and determine how much electric field strength of the electric screen 5 between both electrode rows 1a and 1b should be set. Electric field strength E
[V/cm] and the sweetfish's body length L [cm], using the product E・L as a parameter, and experimentally investigated the reaction of sweetfish when changing this product E・L.
is less than 1 [V], the sweetfish does not react to the electric screen 5 and exhibits positive rheotaxis, and the product E・L is 2.5
When it is larger than [V], the sweetfish loses its swimming ability due to strong electrical stimulation, and when the product E・L is more than 1 [V] and less than 2.5 [V], the sweetfish takes repellent behavior and is unable to return to the upstream side. I understand.

Therefore, by forming an electric screen 5 in water such that the product E・L of the electric field strength E of the electric screen 5 and the body length L is 1 [V] or more and 2.5 [V] or less, the body of the sweetfish can be reduced. without damaging the
It is possible to reliably block the swimming of sweetfish.

As described above, according to the embodiment, when the flow velocity of the water flow in the direction of the prohibited area is 0.1 to 1 [m/sec], the electric field strength of the electric screen 5 and the body length of the sweetfish, which is the fish to be blocked, are 2.5 when the product is 1 [V] or more
[V] Since the electric screen 5 is formed as below, it is possible to give electrical stimulation to the fish to the extent that it can take repellent behavior without damaging the fish body, and it reliably blocks the swimming of the sweetfish. It is possible to prevent sweetfish from entering inside the water intake of a hydroelectric power plant, which is a prohibited area.

Note that, of course, the number of electrode rows may be three or more rows.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

The velocity of water flow in the direction of the prohibited area is 0.1 to 1 [m/m/
sec], an electric screen is formed such that the product of the electric field strength of the electric screen and the body length of the target fish is 1 or more and 2.5 or less.
It is now possible to apply electrical stimulation to fish such as sweetfish to the extent that they can take repellent behavior without causing damage to the fish body, and it is possible to reliably block fish swimming and prevent fish from entering prohibited areas. It is extremely effective in blocking fish from swimming in water intakes of hydroelectric power plants.

[Brief explanation of drawings]

The drawings show one embodiment of the method for blocking the swimming of fish according to the present invention, with FIG. 1 being a perspective view and FIG. 2 being a schematic diagram. 1a, 1b... Electrode row, 5... Electric screen.

Claims (1)

[Scope of Claims] 1. A plurality of electrode rows are arranged in parallel in water, a voltage is applied to each of the electrode rows to form an electric screen with a predetermined electric field strength between the electrode rows, and the electric screen In a method for blocking fish from swimming in a prohibited area, the velocity of the water flow in the direction of the prohibited area is 0.1 to 1.
[m/sec], the product of the electric field strength of the electric screen and the body length of the fish to be blocked is 1 or more and 2.5 or less. .