BACKGROUND ART In general, banks and floodgates are provided in some regions of rivers so that the quantity of storage water can be adjusted by selectively opening and closing the floodgates according to the water level.

However, dams or estuary dikes installed at river mouths may close passages of migratory animals such as sweetfish, eel and king crab which inhabit both of the sea and the river, and thus cause extermination of corresponding species. In addition, a dam built in the river also closes a passage of local migratory fish such as minnow and slender bitterling which propagate in number and migrate upstream when water temperature rises in spring but migrate downstream for wintering when water temperature lowers down and water quantity is decreased in autumn.

This as a result simplifies fish fauna upstream of the dam.

Accordingly, a fishway is installed independent from a floodgate in order to minimize the influence to the ecosystem.

According to the typical concept of the fishway, when water is contained above a preset water level, a floodgate is opened to drain water to the preset water level thereby forming a waterway which also functions as a natural fishway. When water is contained under the preset water level, the floodgate is closed until reaching the preset water level in order to maintain a predetermined quantity of storage water. Then, the fishway is formed via the waterway owing to drain water only when water is stored above the preset quantity and the floodgate is opened, but not formed in the dry season since water is not drained.

As a problem, this reduces the number of anadromous fish.

When the floodgate is opened since water is stored above the preset water level, flow rate changes according to the quantity of drain water, but in this case, specific kinds of fish can migrate according to the flow rate. This may disadvantageously decrease fish species other than the specific kinds of fish.

DISCLOSURE OF THE INVENTION Accordingly, the present invention has been devised to solve the foregoing problems of the prior art, and it is an object of the present invention to provide an automatic variable fishway by water level sensed capable of automatically varying its height to uniformly maintain the quantity of water drained through the fishway so that water can be drained along the fishway at a fixed flow rate and quantity regardless of the level of storage water so as to ensure, a predetermined quantity of water constantly thereby preventing flood while effectively protecting river ecosystem.

It is another object of the invention to provide an automatic variable fishway by water level sensed capable of modifying or varying partitions of the fishway having a predetermined interval according to installation environments in order to form most effective fishways according to installation sites, which can facilitate maintenance while effectively dispersing the weight of water drained along the fishway.

According to an aspect of the invention, there is provided an automatic variable fishway by water level sensed installed in a bank for storing a predetermined quantity of water to allow migration of fish, comprising: an underwater gate for being erected or laid by a drive means which is operative in response to a signal from a water level detecting sensor for detecting the level of storage water; and a fishway plate connected with a top of the underwater gate to form a migration path for fish.

Preferably, the fishway plate has a plurality of moving means formed at both lateral sides thereof, the moving means functioning to disperse weight and being movable according to the erection or lying of the underwater gate.

Preferably, each of the moving means includes: a plurality of slide rollers projected from both lateral sides of the fishway plate; a plurality of guide recesses formed elliptically in side walls to seat the slide rollers therein; and sheets for blocking foreign materials, the sheets being provided in spaces between above the slide rollers and the side walls.

Preferably, each of the moving means includes: a plurality of inside slide rollers mounted on a side of the fishway plate; and a plurality of projected guides fixed to a side wall, and having elliptic slide faces for slidably seating the slide rollers.

Preferably, each of the moving means includes: a plurality of rollers formed on a side of the fishway plate, the rollers being movable on a side wall to dispersing the weight of the fishway plate; and a plurality of movable supports provided in a bottom of the fishway plate, and extensible according to the weight of the fishway plate.

Preferably, the fishway plate has a plurality of detachable conical partitions forming a migration path for fish, wherein the conical partitions are arranged to alternate with each other or grouped according to their directions so that conical partition groups are arranged to alternate with each other.

Preferably, the fishway plate has a plurality of detachable partitions forming a migration path for fish, and wherein the fishway comprises one selected from the group consisting of a stepped fishway, a vertically slotted fishway, an ice harbor type fishway and a baffled fishway.

Preferably, the drive means includes: a hinge fixed to a bottom of the underwater gate; a connector plate fixed to an end of the hinge; a hydraulic cylinder hinged to the connector plate to turn the connector plate; and a control box for outputting a control signal to operate the hydraulic cylinder in response to a signal from the water level detecting sensor.

Preferably, the drive means includes: a hinge fixed to a bottom of the underwater gate; a following gear connected to the hinge; a drive gear meshed with the following gear; a drive motor for turning the drive gear; and a control box for outputting a control signal to operate the drive motor in response to a signal from the water level detecting sensor.

Preferably, the drive means includes: a wire rope connected to a top of the underwater gate to erect or lay the underwater gate; an upper guide roller provided adjacent to the top of the underwater gate to support the wire rope; a lower guide roller provided adjacent to a bottom of the underwater gate to support the wire rope; a bobbin for winding the wire rope ; a drive motor for turning the bobbin; and a control box 1 for outputting a control signal to operate the drive motor in response to a signal from the water level detecting sensor.

BRIEF DESCRIPTION OF THE DRAWINGS The above objects, other features and advantages of the present invention will become more apparent by describing the preferred embodiments thereof with reference to the accompanying drawings, in which: FIG. 1 is an illustration automatic variable fishways by water level sensed according to a first embodiment of the invention; FIG. 2 illustrates a schematic construction of an automatic variable fishway by water level sensed according to the first embodiment of the invention; FIG. 3 is a cross-sectional view taken along the line A-A in FIG. 2; FIG. 4 illustrates a schematic construction of an automatic variable fishway by water level sensed according to a second embodiment of the invention; FIG. 5 illustrates a schematic construction of an automatic variable fishway by water level sensed according to a third embodiment of the invention; FIG. 6 illustrates a schematic construction of an automatic variable fishway by water level sensed according to a fourth embodiment of the invention; FIG. 7 is a plan view of the automatic variable fishway shown in FIG. 6; FIG. 8 is a cross-sectional view of a part of the automatic variable fishway shown in FIG. 6 for the purpose of illustrating slide rollers; FIG. 9 is a cross-sectional view of a part of the automatic variable fishway of the invention for the purpose of illustrating a drain-side connector ; FIG. 10 is a schematic cross-sectional view of the automatic variable fishway by water level sensed according to a fifth embodiment of the invention; FIG. 11 is an enlargement of the part A in FIG. 10; FIG. 12 illustrates the upstream migration of fish in the fishplate according to the first embodiment of the invention; and FIGS. 13 to 16 are perspective views of variable fishway plates which are applicable to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

An automatic variable fishway by water level sensed of the invention will now be described with reference to the accompanying drawings.

FIG. 1 is an illustration automatic variable fishways by water level sensed according to a first embodiment of the invention, FIG. 2 illustrates a schematic construction of an automatic variable fishway by water level sensed according to the first embodiment of the invention, FIG. 3 is a cross-sectional view taken along the line A-A in FIG.

2, FIG. 4 illustrates a schematic construction of an automatic variable fishway by water level sensed according to a second embodiment of the invention, FIG. 5 illustrates a schematic construction of an automatic variable fishway by water level sensed according to a third embodiment of the invention, FIG. 6 illustrates a schematic construction of an automatic variable fishway by water level sensed according to a fourth embodiment of the invention, FIG. 7 is a plan view of the automatic variable fishway shown in FIG. 6, FIG. 8 is a cross-sectional view of a part of the automatic variable fishway shown in FIG. 6 for the purpose of illustrating slide rollers, FIG. 9 is a cross-sectional view of a part of the automatic variable fishway of the invention for the purpose of illustrating a drain-side connector, FIG. 10 is a schematic cross-sectional view of the automatic variable fishway by water level sensed according to a fifth embodiment of the invention, FIG. 11 is an enlargement of the part A in FIG. 10, FIG. 12 illustrates the upstream migration of fish in the fishplate according to the first embodiment of the invention, and FIGS. 13 to 16 are perspective views of variable fishway plates which are applicable to the invention.

Referring to FIG. 1, automatic variable fishways 100 by water level sensed according to the invention are installed at edges of a floodgate 200 built in a river.

Since fish tend to move along edges of the river, the fishways 100 are preferably installed near the edges of the river.

As shown in FIGS. 2 and 3, an automatic variable fishway 100 by water level sensed according to the first embodiment of the invention includes an underwater gate 170 designed to lie or erect according to water level and a fishway plate 110 connected to the top of the underwater gate 170 to form a fishway of a predetermined length. In this case, the fishway plate 110 is preferably designed to form a fishway about at least 20 times longer than the depth of contained water. The fishway plate 110 is adapted to stably slide along side walls 140 as well as move vertically and laterally according to the height of the underwater gate 170 while maintaining the fishway.

The fishway plate 110 is connected at one end to the top of the underwater gate 170 via a fishway hinge 178.

The fishway plate 110 is adapted at the other end to move to the right and left on the ground via a drain-side connector 150. In addition, the fishway plate 100 is moved vertically and laterally via a movable roller 131 and a variable support 60 in response to the height adjustment of the underwater gate 170. The variable support 60 preferably utilizes a plurality of shock absorbers. On the top of the fishway plate 110, a plurality of conical partitions 112 are projected to a predetermined height and arranged at a predetermined interval across water current in order to decelerate the speed of running water. The conical partitions 112 each are tapered at one end. The conical partitions 112 are arranged to alternate with each other. Alternatively, the conical partitions 112 may be grouped according to their directions, and conical partition 112 groups may be arranged to alternate with each other.

The underwater gate 170 is connected by the top to the fishway plate 110 via the fishway hinge 178 as described above and by the bottom to the ground via a hinge 40. Connector plates 30 are fixedly connected to both ends of the hinge 40, and a hydraulic cylinder 20 is connected to one of the connector plates 30 to turn the hinge 40.

The hydraulic cylinder 20 is operated by a control unit in a control box 10. In response to an output signal from a water level detecting sensor 50, the control unit operates the hydraulic cylinder 20 to lay or erect the underwater gate 170.

The water level detecting sensor 50 preferably comprises an ultrasonic sensor which correctly detects the water level according to a known technology. Preferably, the hydraulic sensor 20 is designed to remain parallel with the ground even if the underwater gate 170 is completely laid.

At an inlet side of the underwater gate 170, a connector 174 made of flexible synthetic resin is closely contacted with the ground in order to prevent introduction of foreign material or water to the underwater gate 170. A junction of the underwater gate 170 with the fishway plate 110 is also sealed by an upper connector 176 like the inlet-side connector 174. The side walls 140 and the fishway plate 110 are also sealed by sheets 114 for blocking foreign materials like the inlet-side connector 174.

While the hydraulic cylinder 20 has been illustrated as an example in the first embodiment, the invention is no way limited thereto. That is, it will be apparent to those skilled in the art that the hydraulic cylinder can be replaced by a pneumatic cylinder.

Referring to FIG. 4, an automatic variable fishway by water level sensed according to the second embodiment of the invention includes a following gear 72 connected with a hinge 40 to lay or erect an underwater gate 170, a drive gear 71 meshed with the following gear 72 and a drive motor 70 for turning the drive gear 71. The drive motor 70 includes a decelerator to deliver a sufficient amount of driving force. In the automatic variable fishway of this embodiment, a fishway plate 110 and the underwater gate 170 each have substantially the same construction as that in the foregoing first embodiment.

That is, the drive motor 70 is operated in response to a water level detection signal from a water level detecting sensor 50 to erect or lay the underwater gate 170, which in turn automatically adjusts the height of the fishway plate 110 connected with the underwater gate 170 according to water level.

Referring to FIG. 5, an automatic variable fishway by water level sensed according to the third embodiment of the invention includes a wire rope 80 having one end connected with the top of an underwater gate 170 to lay or erect the underwater gate 170, a bobbin 83 for winding the wire rope 80 and a drive motor 70 for turning the bobbin 83. The wire rope 80 is supported by an upper guide roller 82 fixed to the top of the underwater gate 170 and a lower guide roller 81 fixed to the bottom of the underwater gate 170.

In the automatic variable fishway of this embodiment, a fishway plate 110 and the underwater gate 170 each have substantially the same construction as that in the foregoing first embodiment.

In the third embodiment, the drive motor 70 is operated in response to a water level detection signal from a water level detecting sensor 50 to wind or unwind the wire rope 80 on or from the bobbin 83 thereby erecting or laying the underwater gate 170. Then, the fishway plate 110 connected with the underwater gate 170 is automatically adjusted in height in response to the erection or lying of the underwater gate 170.

Referring to FIGS. 6 to 11, automatic variable fishways by water level sensed each include a means for vertically and laterally moving a fishway plate 110. In this case, an underwater gate 170 is adopted from one of those disclosed in the foregoing first to third embodiments.

In the fourth embodiment of the invention, the moving means includes a plurality of slide rollers 130 projected from both lateral sides of the fishway plate 110 and a plurality of elliptic guide recesses 120 formed in side walls 140 to slidably receive the slide rollers 130 therein.

The slide rollers 130 are connected with the fishway plate 110 via roller shafts 132, and synthetic sheets 114 for blocking foreign materials are installed in spaced between the side walls 140 and the fishway plate 110 in order to prevent the introduction of foreign materials. The synthetic sheets 114 are designed to move in response to vertical movement of the fishway plate 110. The synthetic sheets 114 are mounted on the fishway plate 110 at a predetermined lateral height enough to prevent the leakage of water which is drained along the fishway. In addition, the guide recesses 120 each are formed elliptically along the locus of movement of the fishway plate 110 according to the erection or lying of the underwater gate 170, and securely fixed to the side walls 140 via for example anchors so as to form different loci according to various environments in which the fishway plate 110 is installed.

In the moving means according to the fifth embodiment of the invention, projected guides 190 are fixed to side walls 140 so that inside slide rollers 192 mounted on lateral sides of a fishway plate 110 can slide on the projected guides 190 unlike the fourth embodiment in which the guide recesses 120 are formed in the side walls 140.

That is, slide faces 191 are formed elliptically and fixedly inserted into the side walls 140 so that the slide rollers 192 mounted on the lateral sides of the fishway plate 110 can slide on the slide rollers 192. In order to prevent introduction of foreign materials to a region of each of the slide rollers 192 which slide on the slide faces 191 of the projected guides 190, a blocking sheet 193 having a catch 196 at one face is provided in a movable fashion within a space 195. In addition, a plurality of rollers 194 are provided at sides of the fishway plate 110 to rotate on the side walls 140 in order to prevent movement of the fishway plate 110.

A connector 150 may be provided at a drain side end of the fishway plate 110 according to any of the first to fifth embodiments. The drain-side connector 150 is so formed that a connector plate 152 closely contacts the ground to prevent introduction of foreign materials inside the fishway plate 110 even during movement of the fishway plate 110. That is, the connector plate 152 is designed to closely contact the ground when moving thereon under the weight of the connector plate 152 about a hinge shaft 154 connected to the end of the fishway plate 110.

FIG. 12 illustrates the fishway plate according to the first embodiment of the invention, in which the conical partitions 112 are arranged in an alternating fashion to reduce flow rate. That is, drain water zigzags and decelerates in the fishway plate 110, and a predetermined quantity of water can be stored according to the variation in height of the conical partitions 112 to form pools where fish can take a rest, thereby more facilitating the migration of the fish.

FIG. 13 illustrates a stepped fishway, FIG. 14 illustrates a vertically slotted fishway, FIG. 15 illustrates an ice harbor type fishway, and FIG. 16 illustrates a baffled fishway.

Fishway types are classified into a pool type fishway, a waterway fishway, an operative fishway and the like. The pool type fishway is illustrated in the embodiments of the invention. In the first embodiment, two of the conical partitions 112 are paired so that conical partition 112 pairs are arranged in an alternating fashion. The stepped fishway is so designed that fish can swim over the stream flowing over partitions, and the vertically slotted fishway is so designed that fish migrate through vertical slots formed in partitions. The ice harbor type fishway has notches at both lateral sides. In addition, the pool type fishway includes an orifice type fishway. While the pool type fishway has advantages of easy installation and small construction cost, this is disadvantageously available for only limited species having excellent swimming ability and jumping force.

While various types of fishways as described above can be applied to the invention, various types of partitions of the pool or waterway fishway can be detachably installed in the fishway plate 110 of the invention, in which partitions having a plurality of brackets formed at both lateral sides are mounted on the fishway plate 110.

Describing the operation of the invention constructed as above, water level is detected by the water level detecting sensor 50. In response to the detected water level, the underwater gate 170 is controllably operated to lie or erect at a height at about 20cm under lower water level.

When the underwater gate 170 is erected of laid, the fishway plate 110 connected via the fishway hinge 178 is raised or lowered, especially along the fishway guide recesses 120 in the fourth and fifth embodiments.

Then, storage water is drained along the underwater gate 170 and the fishway plate 110, and its flow rate is decelerated by a plurality of partitions mounted on the fishway plate 110.

That is, the conical partitions 112 are tapered and arranged so that tapered portions of adjacent ones of the conical partitions 112 are directed counter to each other.

Then, drain water zigzags in the fishway plate decelerating its flow rate. In addition, a predetermined quantity of water can be stored according to the variation in height of the conical partitions 112 to form pools where fish can take a rest, thereby more facilitating the migration of the fish.

When the water level detecting sensor detects the top water level at floods due to heavy rain, the floodgate can be opened completely to maximize the quantity of drain water to prevent submersion of upstream areas.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

INDUSTRIAL APPLICABILITY As described hereinbefore, the invention can automatically adjust the height of the fishway plate according to water level to constantly form a fishway thereby allowing free migration anadromous fish. This accordingly can provide uniform environments according to various kinds of fish thereby protecting ecosystem.

The partitions installed lengthwise can be modified or varied according to fishway environments to provide the most effective fishway, and maintenance is facilitated since the partitions are detachable.

Furthermore, the invention can effective disperse the weight of water drained along the fishway to stabilize the operation of the fishway, and maximize the quantity of drain water at floods due to heavy rain to prevent submergence of upstream regions.