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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Hydro-environment : Fish damage and fish protection at hydro power plants experimental investigation of small fish under...
Fish damage and fish protection at hydro power plants experimental investigation of small fish under laboratory conditions
Author : FRANZ GEIGER(1), STEFAN SCHÄFER(2) & PETER RUTSCHMANN(3)
ABSTRACT
With increasing ecological awareness and consequential legislation fish downstream migration and thus fish protection are
becoming an essential but relatively unresolved aspect for the implementation and continuance of hydro power usage.
The most common approach to prevent fish from passing through a turbine and being subjected to the joint mortality rates
is a mechanical barrier, i.e. a screen. An adapted approach velocity and downstream passage bypass are required
furthermore. The mechanical barrier does in principle only account for relatively large fish and there remains a lack of
knowledge concerning small individuals. Fish downstream passage of fish smaller than the bar clearance was investigated
at a TUM-Hydro Shaft Power Plant prototype facility under nature like but controlled laboratory conditions to elucidate fish
protection and fish downstream passage for small fish and weak swimmers which can physically pass through the screen
and may subsequently be damaged in the turbine.
In a large scale open air laboratory channel of the Technical University of Munich a fully functional 35 kW hydro power
plant was installed, featuring a horizontal screen with 20 mm bar clearance. The test setup was sealed against the
surrounding river system with 4 mm aperture fish barriers. Fish ensembles with body length from 5 cm to 20 cm were
introduced in the head water. The fish movement at the hydro power plant, the migration movements and possible injury to
the fish were recorded during the 24 h test periods. Subsequently all fish were extracted and observed for 96 h to account
for possible long term damage. About 2000 brown trout, grayling, barbel, bullhead and minnow were investigated for three
different approach velocities at the screen respectively turbine discharges and two different downstream migration bypass
configurations. The detailed records of the test series include fish species, fish length, passage path, observed injury,
turbine discharge and bypass arrangement for each individual. The statistical analysis of the data revealed species and
size dependent characteristics of fish downstream passage and mortality rates. The screen did effectively serve as
behavioral barriers for partitions of the small fish and the extent of the partition was influenced by the facility design. The
partition of fish which passed through the screen and the turbine was subjected to turbine specific injury and mortality
rates. Opposing trends with regard to screen passage/turbine passage and mortality rates entail relatively homogeneous
mortality rates for different fish sizes, species and service conditions. The study enables in principle the targeted design of
hydro power facilities at specific river sites in order to meet the required ecological obligations at best economic efficiency.
File Size : 1,446,011 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Hydro-environment
Date Published : 19/08/2015
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