Fish canoe pass
A fish canoe pass (brush fish pass, bristle pass) is a combination of a fish pass (fish pass, fish ladder, fish pass) and boat lane (boat passage) in one channel.
The fish canoe pass was developed by the test center for environmental technology and hydraulic engineering at the University of Kassel under the direction of Reinhard Hassinger.
It is a channel between the headwater of a dam or weir and the underwater in a flowing water , i.e. a river or stream . But even in stagnant waters that contain barrages (e.g. canals), fish-canoe passes can be used to create patency for animals and people. With this channel, the water level difference is overcome with a gradient of approx. 1:20. In principle, steeper systems up to 1:10 or 1: 8 are also possible, although the criteria for fish passes are difficult to meet. On the bottom of the channel, bristle elements are arranged like upturned brooms as elastic disruptive bodies. The bristle blocks are raised with threaded bolts; the entire bed is filled with river rubble and gravel as a bed substrate .
Recently, the bristle blocks are arranged in bars, with two to three bars forming a group. Between the groups there are basins as recreation and relaxation areas for larger fish. This reduces the flow speed between the elements to 1.0–1.4 m / s (depending on the height of fall at a group of bars) and in the flow shadow of the elements to 0.10 to 0.30 m / s, thus enabling all types of fish to climb .
The most recent functional checks show excellent ascent figures (e.g. 14,180 fish in 21 days), whereby the high proportion of small fish (<5 cm) is remarkable.
Canoes can go down over the brushes or slide down on the brushes when the water is low.
Well-known systems of this type are located in Lippstadt (Wehr Esbeck, Lippe), Hann. Münden (Fulda weir, Fulda), Braunschweig-Rüningen (Oker), Burg / Spreewald (Kongoa weir, Stilles Fließ), Cham and Chamerau (Regen), Fürstenberg (Havel), Osnabrück (weir Neue Mühle in der Hase), Budin ( Sazava River, Czech Republic) and Porter's lock (River Medway, England). A total of around 30 systems are in operation.
The fish canoe pass is based on the bristle fish pass concept, which has advantages over conventional construction methods in terms of hydraulic parameters .