Roof weir

Roof weir regulating Lake Zurich near Letten

above: weir in raised position, below: weir in lowered position

The roof weir (also: double flap weir , bear trap ) is one of the movable weirs with overflow lock.

function

A roof weir consists of a lower and an upper flap, which are rotatably mounted on the river bed. The top flap overlaps the bottom flap. A float under the lower flap regulates the height of the lower flap depending on the water level in the space between the upper and lower flap. The weir can be adjusted without a motor drive by directing more or less water into the space under the flaps. For this purpose, water is taken from the upper water to raise the weir and to lower the weir, it is drained back into the lower water.

Examples

• Weir at Göstling ^▼ of the Opponitz power plant
• Weir ^{▼ of} the Tübinger Strasse river power station , the largest roof weir in Europe
• Lettenwehr ^▼ to regulate Lake Zurich
• Weir ^▼ at the outflow of Lake St. Moritz ( Islas power plant )
• Weir ^▼ Wildegg-Brugg power plant near Schinznach-Bad

literature

• Kurt Lecher, Hans-Peter Lühr, Ulrich CE Zanke: Pocket book of water management . 8th completely revised edition. Vieweg, Wiesbaden 2003, ISBN 3-528-02580-8 .
• Theodor Strobl, Franz Zunic: Hydraulic engineering. Current principles, new developments . Springer, Berlin et al. 2006, ISBN 3-540-22300-2 .

Individual evidence

1. ↑ How a roof weir works . In: Wasserfahrverein Zürich (Ed.): The wave . No. 79 , July 2007, p. 3 ( paddeln.ch ).
2. ↑ Ulrich Eisele: Europe's largest roof weir is being renovated. In: Schwäbisches Tagblatt. August 1, 2009, accessed May 29, 2020 . 

 Map with all coordinates: OSM | WikiMap