Michel Larinier

Fish passage experience at small-scale hydro-electric power plants in France

There are more than 1,700 small-scale hydro-electric power stations in France today, which can be found on the majority of rivers with migratory species in them. This article gives an overview of the different types of fish facilities in use at these small-scale hydro plants. The relative advantages and drawbacks of each type of fish pass are discussed, with reference to the requirements of migratory species and the site-specific constraints. Emphasis is placed on the problems of attraction and maintenance. The article also mentions the various techniques used to evaluate existing or recently constructed fish passes. Experience in using bypass facilities combined with trashracks for downstream juvenile salmonids and eels are related. The author points out the severe cumulative impact which may occur due to the existence of several small-scale hydro projects on the same river. He presents his view on the priorities for research on fish passage facilities, especially on “fish friendly” small-scale hydropower intakes.

Streamwise bars in fish-friendly angled trashracks

Experimental results for fish-friendly trashracks placed in an open-water channel are presented. Eighteen angled trashracks were used to test different bar spacings, bar shapes and rack angles. Each model trashrack comprised two horizontal supports with regularly spaced slots adjusted to compensate for the trashrack angle, i.e. maintain the vertical bars “streamwise” (parallel to flow). Water depths and velocity profiles were acquired upstream and downstream of each rack configuration. The results reveal that the head-loss coefficient for angled racks with streamwise bars does not depend on the rack angle and can be calculated with equations for racks perpendicular to the channel. Upstream velocity profiles along the rack are not significantly affected by the rack angle and downstream transverse profiles are nearly uniform. A comparison with conventional angled trashracks with bars set perpendicular to the rack revealed the many advantages of streamwise bars.

Closure to “An experimental study on fish-friendly trashracks: part I & II”

The Authors thank the Discussers for their observations on our two papers. Four main points, related to head-loss predictions for angled trashracks, have been underlined by the Discussers and are discussed here.[...]