The main use of the fishways is to enable migrating fish to pass over the barriers, normally power plant dams, and to rise upstream in a river system. Generally, there are two types of fishways. A fish ladder attempts to mimic a natural fishway. A fish ladder is difficult to be carried out if the height of fall is great. Then, a fish ladder will be a long, complicated, and expensive construction. Moreover, the implementation of a fish ladder is quite complicated for lower heights, too, and careful design is always required. A simpler solution is a lock-type fishway, the most common implementation of which is also known as the Borland fishway. An advantage thereof, in comparision with the ladder-type fishway, is that it is structurally much more simpler and may be implemented within a remarkably smaller space.

The lock-type fishway is also more suitable to be applied on higher power plant dams.

In Finland, the most of the river systems dammed up and equipped for production of electric power, are still lacking fishways, and the main reason for this are the expenses which the building of the fishways would result in. In addition to the design and building costs of the fishways the energy company also looses a remarkable amount of hydropower, because the water discharge of the fishway is reduced from the hydropower production. Accordingly, the operating expences of the fishways are quite high. If a fishway is built, the aim is often to keep the flow rate of the fishway as low as possible, which makes the operation of the fishway less satisfactory. Obviously, the fishways were much more attractive for the energy companies, if an essential reduction in the loss of the hydropower could be provided. An object of the invention is to provide a solution achieving such a reduction.

For realizing the above and other objects of the invention, the fishway system of the invention is characterized in what is claimed in claim 1 of the attached claims. Other claims define different embodiments of the invention.

Fishway system according to the present invention including a lock-type fishway, which includes: a first part from which there is a connection to tail-water for discharging water therethrough and thereby luring fishes from the tail-water to said first part; a second part from which there is a connection to upper water; a first pipe or equivalent between the first part and the second part; and means for filling periodically the first pipe or equivalent with water for bringing fishes from the first part to the second part and from there onwards to the upper water, is characterized in that it includes in parallel relationship to the fishway between the upper water and the first part a second pipe or equivalent and therein a turbine for conducting the luring water therethrough and for recovering energy from the luring water.

The main advantage of the invention is that the discharge of water needed for luring fishes to the fishway is continuously producing energy, and so the loss of hydropower is kept low. Remarkably great discharges of water may be used in the fishway and the performance of the fishway may thereby be improved without raising the operational expenses unacceptably. At the same time the structural simplicity of the lock-type fishway may be maintained. As the luring water flow rate may be maintained high, there may be several different types of entrance openings of the fishway suitable for different species of fishes. So, the entrance openings are easily found. The fishes find also the rising channel easily, and the risk of remaining under high pressure is small. Especially, if the rising pipe is steep, a lot of light is got to the pressure chamber, which makes the rising of the fishes easier.

The invention and some embodiments thereof are described in further detail in the following with reference to the accompanying drawings, wherein: Figs. 1 and 2 illustrate schematically a prior art lock-type fishway and the operation thereof ; Fig. 3 is a schematic sectional top view through the fishway and turbine pipe of an embodiment of the fishway system according to the invention; Fig. 4 is a schematic sectional side view through the turbine pipe of an embodiment of Fig. 3; Fig. 5 is a schematic sectional side view through the rising pipe of an embodiment of Fig. 3; Fig. 6 is a schematic sectional side view of another embodiment of the invention ; Fig. 7 presents an alternative of carrying out the pipes of the fishway system according to the invention; Fig. 8 presents another alternative of carrying out the pipes of the fishway system according to the invention; Fig. 9 is a schematic sectional top view presenting a further alternative of carrying out the pipes of the fishway system according to the invention; Fig. 10 is a schematic sectional top view presenting a further embodiment of the fishway system according to the invention; Fig. 11 is a schematic sectional side view through the fishway of a further embodiment of the fishway system according to the invention; and Fig. 12 is a schematic sectional side view through the turbine pipe of the embodiment of Fig. 11.

A starting point in the invention is the lock-type fishway, and therefore a simplified description of such a prior art fishway is presented in the following with reference to Figs. 1

and 2. In Fig. 1 above there is a schematic sectional side view through a lock-type fishway, and below there is a shematic sectional top view of the same, the section being taken along the fishway. The fishway is located on a dam structure 3. From a first part 9 of the fishway there is a connection, opening 12, to tail-water 2. The opening is provided with a gate 13. A second part 4 of the fishway is connected to upper water 1 via an opening 6 in a wall 5. The second part 4 is separated from the upper water by a gate 7, by means of which water flow to the fishway may be regulated. A rising pipe 8 connects the first part 9 to the second part 4.

The first part 9 is container-like, confined by walls 10,11, and the second part 4 is basin-like.

In operation, water is discharged via the first part 9 to the tail-water 2 for luring fishes from the tail-water through the opening 12 to the container-like part 9. Water is normally discharged directly from the upper water by suitably adjusting the gate 7, as is shown in Fig.

1 above by arrows and reference sign F. When a long enough time is spent for luring and accumulating fishes to the container 9, the opening 12 is closed by the gate 12, as is seen in Fig. 2. At the same time the gate 7 is opened, whereby first the container 9 and then the pipe 8 are filled with water. Fishes, which are accustomed to swim under a small pressure close to the water surface, like to keep themselves close to the water surface and thereby rise with the rising water via the pipe 8 to the basin 4 from which they are able to pass to the upper water.

The operation cycle of this type of fishway may be 1 to 4 hours, for example.

Figs. 3 to 5 present a fishway system according to the invention, which includes a lock- type fishway 4,8,9 and in a parallel relationship thereto a pipe 20 connecting the upper water 1 to the first part 9 of the fishway, the pipe 20 being for providing water flow for luring fishes to the fishway and for recovering energy from the luring water by means of a turbine 23 installed in the pipe. The structure and operation of the fishway of Figs. 3 to 5 are described in further detail in the following.

The basin-like part 4 which is connected to the upper water 1 is conventional. In the wall 5 which is against the upper water there are the opening 6 and gate 7, by means of which the discharge of water from the upper water to the fishway may be adjusted. The lock and gate arrangements may include separate arrangements for the rise of fishes on the other hand and for supplying water to the fishway on the other hand. An overflow wall 18 separates the basin 4 from the rising pipe 8 and keeps water in the basin. Walls 10 which are made of concrete, for example, form a closed space including a container or pressure chamber 15, which is in connection with the tail-water 2 and to which fishes are introduced for rising, and the rising pipe 8, which is open at the upper end only. The opening 12 leads from the container 15 to an open rerceiver pool 16 from which a relatively narrow opening 17 leads to the tail-water 2.

The opening 12 is closeable by a gate 13. Also the other pipe 20 starts from the upper water.

An opening 19 from the upper water to the pipe 20 is provided with a gate 21, by means of

which the flow of water to the pipe may be adjusted or totally closed for maintenance operations, for example. A turbine 23 is located in the pipe 20, and for avoiding cavitation the turbine is preferably located below the tail-water surface 2'. The turbine 23 is located in an expansion 22 in the tube 20, and after the turbine 23 the construction includes a draft tube 24 and space 25 from which there is a connection to the pressure chamber 15 via an opening 27 and to the receiver pool 16 via an opening or space 26. By means of a gate 28 the luring water coming from the turbine pipe 20 is normally conducted via the pressure chamber 15 and the opening 12 to the receiver pool 16 and therefrom via the opening 17 to the tail-water, whereby it lures fishes first from the tail-water 2 to the receiver pool 16 and then from the receiver pool to the pressure chamber 15 for rising. When the filling of the fishway 15,8,4 with water is started the gate 28 is turned to close the opening 27 between the draft tube 24 and space 25 and the pressure chamber 15, and to open the connection from the draft space to the receiver pool 16. Then, the luring water flows via the receiver pool 16 and opening 17 to the tail-water and lures fishes to the receiver pool 16 to wait access to the pressure chamber or container 15. A net or equivalent 30 prevents the access of the fishes from the receiver pool 16 to the draft space 25. In the same way a net or equivalent 29 prevents the access of the fishes from the pressure chamber 15 to the draft space 25.

The turbine 23 may be any suitable device which are today easily available. A suitable device is, for example, a tubular turbine which has a propeller turbine and a generator on the same axis. The power may be a suitable power within a range of 20 to 500 kW. This kind of turbines are available as water-tight units which may be installed directly in a water pipe or equivalent. The construction of the turbine is compact, and the necessary accessories need also a small space. There may be only a small building visible above ground for electric station and automatic control equipment. This as such well known technology is not described here in further detail.

The pipe 20 with the turbine 23 and the draft tube 24 and space 25 are also built by applying the well known techniques. The discharge and the height of fall are advantageously maintained as approximately constant. The loss of energy is tried to be maintained as small as possible, before conducting the water to the pressure chamber 15, and also the loss of energy between the pressure chamber 15 and the tail-water 2 is kept as low as possible, whereby the most of the total energy may be transformed to electric energy by means of the turbine. A suitable discharge in the turbine pipe depends on the application and is normally within 0.4 to 4 cubic meters per second. A suitable diameter of the pipe is in the most cases correspondingly within 0.5 to 1.5 meters.

Fig. 6 presents another embodiment of the fishway system according to the invention. A steep solution, which as such is advantageous in many respects, may be accomplished in a

dam structure in such a way that the pipe for a turbine is a horizontal pipe 20 directly through the dam in the lower part thereof, the inlet of which is provided with a suitable gate mechanism 21. Another embodiment suitable for steep solutions is presented in Figs. 11 and 12. There, as is seen in Fig. 11, instead of pipe a vertical shaft 8, which is open at the upper end, rises from the container 15 to the basin 4. This kind of structure is easy to build. Another advantage is that a lot of light is got to the fishway, which makes the rising easier for fishes.

The turbine pipe arrangement is similar to that of Fig. 6, as is seen in Fig. 12. Otherwise, these embodiments are similar to the embodiment of Fig. 4, and equivalent or similar parts are indicated by the same reference signs in said Figs. 4 and 6.

In accordance with the present invention the pipe arrangements may be accomplished in many ways. Some alternatives are presented in with reference to Figs. 7 to 9. In said figures only the turbine pipe is presented as a side view and wholly or partly in section. The rising pipe may be accomplished with the same or some other suitable tecnique. If the fishway is built over an earth dam 34, for example, a practical and advantageous way of accomplishing the pipes is that shown by the separate pipe 20 of Fig. 7 which is supported by suitable means 35. An alternative in such a situation is to build the pipes inside the earth dam 34 in the way shown by Fig. 8. If the dam is formed by rock, the pipe or pipes may be excavated through the rock. A further alternative is a concrete structure, in which the rising pipe 8 and the turbine pipe 20 are accomplished by concrete walls 10,10', and 10"and in which they may be side by side and separated from each other by only one wall 10'. This alternative is well suited for carrying out steep fishways. Otherwise, this fishway system includes the same parts and structures as the embodiment of Fig. 3.

Fig. 10 presents an embodiment which further improves the operating efficiency of the fishway. There is a pipe 31 between the pressure chamber 15 and the draft tube 24. The pipe is provided with an adjustable valve 34 and nozzle means 32 directed to the draft tube. As the fishway is filled with water, the valve 34 is closed, and during the draining phase it is suitably openened for conducting water through the nozzle 32 to the draft tube 24, so that ejector effect is accomplished in the draft tube, which increases the efficiency of the turbine. The inlet of the pipe 31 on the side of the pressure chamber is provided with a net or grating 33 for preventing the access of fishes to the pipe.

A good building material for the basin, container, and draft tube is reinforced concrete, for example. Concrete may be used also for accomplishing other parts of the fishway and turbine pipe. Steel, for example, or some suitable plastic, or fiberglass-reinforced plastic, or even wood may be used for making pipes or channels. A recommendable and widely used material for making the gates is steel or aluminium.

The term"pipe or equivalent"is used in this specification and in the accompanying claims to mean firstly the structure which connects the lower and upper parts of the fishway, and secondly the structure in which the turbine is located. As to the first structure the term "pipe or equivalent"covers structures which may be described by terms conduit, tunnel, or channel, for example, and also shaft-like structures (see Fig. 11). As to the second structure a generally pipe-like or channel-like structure is meant through which the luring water may be conducted and in which the turbine may be located.

A person skilled in the art understands that the parts of the fishway and especially the the lower part of the fishway, which is in connection with the tail-water and which is essential in the present invention, may be accomplished in many different ways. The location and size of the receiver pool and pressure chamber, or equivalent parts, may vary widely. The openings and gates are presented only schematically in the foregoing, and there are a lot of forms and structures by means of which they may be accomplished. It is clear that the gates, valves, etc. need driving and actuating means, and that control means are needed for controlling the whole operation of the fishway. To accomplish these well known techniques are applied. It may be thought, for example, that for the fishway and the turbine there is a common operating and control center, which may be located in a separate small building or in a power plant building.

For practical reasons a preferred gate type is a sliding gate, but also pivotably turnable gates, for example, may be used where applicable. Instead of one gate 28 (Fig. 3) for changing the turbine pipe flow between the pressure chamber 15 and the receiver pool 16, in most cases a separate gate is needed for each direction.

It is clear, also, that any amendments in the operation of the fishway may be utilized in carrying out the fishway of the fishway system according to the invention.

The invention may vary within the scope of the appended claims.