Saturday, 17 November 2018
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Fish love to migrate

For fish being able to migrate up and down rivers is crucial for their survival. Waterways are often blocked by insuperable weirs though.

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The European Water Framework Directive de-mands "ability to pass a waterway for aquatic organisms.” Fish too have a right to barrier freedom. For this purpose, fish stairs have been installed at many weir installations - but these require a lot of space and the maximum height that can be overcome is restricted.

Baumann Hydrotec and Hydro-Energie Roth came up with something special: they invented a fish lift. It easily masters height differences of up to 30 m and is extremely space efficient, needs far less space than a fish stairway and is cheaper too.

Lift can boast about its energy efficiency

The central component is a floating piston, which moves up and down in a waterfilled tube. The fish are lured into the floating piston by the current, which is carried upwards by water power. Upon reaching the top, the container opens and the fish can swim further.

Just how long the trip in the fish lift takes – as in passenger lifts – depends on the conveyance height. If the height to be overcome is 10 m, the trip takes about a leisurely ten minutes. The fish lift definitely does not break any speed records. But it can boast about its energy efficiency: since it is moved mainly by water power, it uses just a little electricity. Only the control of the hydraulic unit requires about 0.35 kW per hour. Swarms of up to 40 fish can be moved in return.

Fish lift provided the solution

Implementation of this technology is planned as a pilot project for Lake Baldeney in Essen (Germany). To comply with the European Water Framework Directive, the Ruhr Association has for some time been looking for a suitable and financially viable fish conveyance option. The area close to the hydroelectric power plant was too cramped for a fish stairway.

The fish lift provided the solution. A lift is now under construction which is intended to provide access to more sources of nutrition and spawning grounds for all 36 species of fish that live in the Ruhr River. And whatever is good for fish cannot be bad for people - for wherever there is a great variety of species, good water quality is also guaranteed.

Stathi Vassiliadis

www.hydroenergie.de

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