Hydraulic Characteristics of Meander-Type Fish Passes

Jürgen Stamm, Ulf Helbig, Rocco Zimmermann

Monday 29 june 2015

17:00 - 17:15h at Europe 1 & 2 (level 0)

Themes: (T) Hydro-environment, (ST) Ecohydraulics and ecohydrology

Parallel session: 3G. Environment - Ecohydraulic

The construction of meander-type fish passes can ensure a river’s passableness. In general we can distinguish between the most frequently employed types, namely C-, J- and H-type. The basic design consists of an alignment of staggered circular basins. Each basin is connected to its neighbour by a slot of variable width. This arrangement creates a meandering main current. Although a large number of meander-type fish passes have already been built, the typical hydraulic characteristics of basins or basin alignments are largely unknown. Because current standards or regulations offer no detailed procedures on how to calculate flow velocity, Torricelli’s simplified law is presently used for hydraulic approximation. The manufacturer’s own empirical data on the design of the fish passes is currently the sole basis for any hydraulic calculation and design. Small discharges Q appear to be sufficient to facilitate the migration of a wide variety of fish species. The determination and compliance of the dominant hydraulic characteristics requires detailed measurements and 3d-hydronumerical simulations. A first reference facility (H-type, River Oker, 20 basins) was selected and studied in some detail. The investigations included field measurements and 3d-hydronumerical simulations. Additionally, the same pass was simulated 3d-hydronumerically as virtual C- and J-type full-size models. At present a C-type is also being investigated by field measurements (River Nethe, 27 basins). The main goal is to collect data on this C-type-facility under diverse conditions (variation of discharges, impact of season, with/without aquatic flora) and to analyse the hydraulic characteristics (water level, current, sensitivity). In parallel, the pass is simulated 3d-hydronumerically as a full-size model to verify the gathered data.