This document proposes an engineering solution to allow fish migration around the Isalnita Dam on the Jiu River in Romania. The solution involves installing a series of metal tanks, bars, rails, and canals along the right bank of the reservoir. Fish would be directed into a metal tank using electric fields, then the tank would slide along a mobile metal bar into an underground canal. This would transport the fish to a second tank and canal system that would guide them either back into the reservoir or downstream into the Jiu River, restoring connectivity for fish populations. The entire system would be automated and monitored to function year-round.

1. The ecotechnical solution IV
Achieving longitudinal connectivity of the Jiu River near Isalnita Dam
Răzvan Voicu
rzvnvoicu@yahoo.com , getiiliberi@gmail.com
This solution regarding fish migration upstream / downstream of the Isalnita Dam involves creating an engineering system on the right bank of the Isalnita Lake. A metal bar will be fixed to the right concrete bank at 100 m distance from Isalnita Dam. The mobile metal bar will be fixed to the bank using metal hinges and a hydraulic telescopic cylinder-shaped piston. (fig.1).
the right bank
the concrete right bank
metal hinges
mobile metal bar
hydraulic telescopic cylinder
Figure 1. Positioning the mobile metal bar – the indicative scheme
A metal tank is attached to the end of the mobile metal bar. When the hydraulic telescopic cylinder is in minimum position, the metal tank is positioned inside the Isalnita Lake (fig.2).

2. the right bank
the concrete right bank
metal hinges
mobile metal bar
Isalnita Lake
hydraulic telescopic cylinder
metal tank (B1)
Figure 2. Positioning the metal tank (B1)
The fish in the Isalnita Lake that want to reach the sluices are directed by means of some electric fields generated by some generators fixed to poles. These metal or concrete poles are fixed to the banks of the Isalnita Lake (fig.3). The poles are fixed to two lines forming an angle to 120 degrees.
electric systems for directing the ichthyofauna
concrete poles
metal tank (B1)
Isalnita Lake
the right bank
mobile metal bar

3. Figure 3. Positioning the systems for directing the ichthyofauna
When the hydraulic telescopic cylinder starts to the maximum position on the upper surface of the tank (B1), there is a flexible rolled up grid closing the metal tank (B1), so that the ichthyofauna within this tank is captured inside. The hydraulic telescopic cylinder lifts the metal bar that supports the tank to the point where, due to gravity, the tank (B1) slides on the bar using the two metal rails. (Fig.3).
metal tank (B1)
metal rails
mobile metal bar
hydraulic telescopic cylinder
Figure 3. Positioning the rails on the metal bar
All components are water resistant. A semicircular canal will be built into the lake bank in the same direction or on the same line with the metal bar in maximum position of tank sliding. (fig.4). The impact between the metal tank and the lake is almost entirely attenuated due to some rubber drums positioned on the lake bank but also due to some metal fixing systems. (fig.4). After the metal fixing systems have been operated, they automatically engage the opening of a metal door belonging to the tank which allows fish to reach the canal in the bank of the Isalnita Lake (fig.5). On the right bank of the lake, near the underground canal build for taking over the ichthyofauna another metal tank will be built (B2) having approximate dimensions: 5x4x3m. The metal tank (B2) for ichthyofauna receiving in the underground canal will be fixed to a concrete foundation in the breakwater. (fig. 6).

4. mobile metal bar (maximum position)
the right bank Isalnita Lake
sluice provided with sensors
metal tank (B1)
automatic system for fixing the tank
rubber drum
hydraulic telescopic cylinder
Figure 4. Underground canal taking over the ichthyofauna from the metal tank for ichthyofauna transportation
receiving metal tank (B2)
Figure 5. Positioning the receiving metal tank(B2)

5. mobile metal bar (maximum position)
the right bank Isalnita Lake
metal tank for ichthyofauna transportation (B1)
weir
automatic system for fixing the tank
rubber drum
hydraulic telescopic cylinder
metal tank foundation (B2)
Figure 6. Positioning the metal tank foundation for receiving the ichthyofauna
The metal tank for receiving the ichthyofauna will be supplied with water from upstream through a metal pipe and its surface will be provided with a loophole which will be directly related to a concrete canal for fish migration. (fig.7 and fig. 8).
connecting loophole
metal receiving tank (B2)
Figure 7. Connecting loophole – indicative scheme

6. metal pipe for supplying the receiving tank with water B2
metal grid
concrete canal for fish migration
metal receiving tank (B2)
Figure 8. Positioning the concrete canal for ichthyofauna migration – indicative scheme
Another metal drum B4 will be fixed for fish resting and recreation between the two access ways, namely the right bank and the one crossing the crest of Ișalnița Dam. This tank B4 will connect the first module of the concrete canal for fish migration to the second module passing under the way crossing the crest of the dam (fig.9 ). Therefore the next module of the concrete canal for fish migration will pass under the road continued by a subterranean sector provided with a lighting system suitable for ichthyofauna.

7. the road reaching the dam crest
the road reaching the right bank of the Isalnita Lake
the first module (M1)
lighting system
the second module (M2) metal tank (B4)
eliminating excess flow pipe from the tank B4
Figure 9. Positioning the metal tank B4 – indicative scheme
The flow of the first module M1 will be about 20% larger than the flow of the second module M2 in order to raise the water level in B4 as to make a connection between the two metal tanks. The water surplus will be taken over by a pipe and discharged directly into the Isalnita Lake. After crossing the dam vicinity, the concrete canal for ichthyofauna migration, that is the second module (M2), will continue its path on the right bank of the Jiu River, maintaining the same slope up to the confluence with the Jiu River. The fixing system of the concrete canal is achieved by means of metal dowels (fig.10). Ichthyofauna will reach the Jiu River into a tank fitted in the river.

8. concrete canal for ichthyofauna migration
the right bank metal dowel
Jiu River
metal bar support
Figure 10. Fixing the concrete canal for ichthyofauna migration to the bank downstream Isalnita Dam – indicative scheme
After the fish have reached the tank B2, they need a system helping them to reach the Isalnita Lake. A metal tank B3 supporting a much smaller amount of water and built to raise fish to a level located above the Isalnita Lake level is fixed inside the tank B2 by four metal bars (fig.11). Therefrom the fish are taken by a metal canal, where its top is funnel shaped and its bottom is simply flat. (Fig. 12). This canal is lined with a layer of rubber.
concrete canal for ichthyofauna migration metal tank B2
bars supporting the tank B3
metal tank B3
electrical systems to redirect the ichthyofauna
Figure 11. Positioning the tank B3 – indicative scheme

9. Two supporting bars have thorns used to lift B3 in the canal in order to take over the ichthyofauna. The tank B3 is lifted by two electric motors symmetrically placed on the two toothed bars. The lifting systems operate according to the cog rack method. When reaching the canal for ichthyofauna taking over, then a sluice automatically lifts allowing the ichthyofauna to reach the channel.
electric motor provided with a ratchet pinion
tank B3
canal for ichthyofauna
taking over
tank B2
toothed bar
Figure 12 Sliding tank B3 method– indicative scheme

10. The tank B3 is fixed on bars by the means of some metal sliding sleeves. The canal for ichthyofauna taking over passes over the right bank of the Isalnita Lake up to 3 metres height in order to not bother the people or vehicles passing along the shore. (Fig.13).
electric motor provided with a ratchet pinion
tank B3
weir
canal used for directing
the fish towards the Isalnita Lake
toothed bar
protective rubber
the right bank
tank B2 Isalnita accumulation
Figure 13 Positioning the canal for fish migration in the Isalnita Lake – indicative scheme

11. eliminating excess flow pipe from the tank B4
electrical systems to redirect the ichthyofauna
the supply pipe
the right bank B1
basin set up in the riverbed
Figure 14 General scheme for ichthyofauna migration system
B2
B3
B4
Isalnita Lake
Jiu River
the road reaching the dam crest
the road reaching the right bank of the Isalnita Lake

12. All components(fig.14) of the ichthyofauna migration systemdownstream - upstream of Isalnita Dam are automated and continuously monitored by those responsible of the dam maintenance. In winter all the system stops because of the frost and lack of ichthyofauna migration. This system can be applied to any lake in the world that has not a high variation of multi-annual water level. All components can be easily replaced, have affordable prices so they can be implemented without question. This solution is designed to achieve the longitudinal connectivity of the Jiu River.
Bucharest
2012