Steering platform

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Three steering bridges on the left bank of the Mürz in Kapfenberg ; Only the standing waves on the water surface are visible

Steerable groynes are a special low construction of the river groynes , which are completely below the water surface. They are overflowed even at low tide and are supposed to create a spiral flow.

application areas

Almost completely overflowing steering grooves on the bank of the Aschbach

Steering grooves have been used so far in the areas of bank protection, water structuring and bed load regulation.

The focus of the bank protection is the securing of impact banks, where steering bridges are installed in order to shift the streamline and the valley path towards the inner bank and thus relieve the impact bank. For this purpose, the steering platforms are usually arranged in groups.

Inclinant flow funnel from steering groynes in the meadow in Lörrach

Steering platforms arranged on both sides are primarily used to structure largely straight sections of water. These "flow funnels" cause an increase in flow diversity with the resulting depth variance and substrate sorting, which in particular improves the living conditions for the fish fauna. In addition, depending on the arrangement and geometry, they can also be used to improve bank protection.

In addition to the pure structuring of the sole, steering gates can also be used to effect additional shifts in running with the formation of bend-like impact and sliding slope structures. Experience in this regard is still limited, but the results of a first nature test at the Bookbräke in the Oldenburg district with a group of steering gates arranged on one side are positive.

To regulate the transport of bed load, steering gates have so far been installed mainly downstream of run- of -river power plants . The landings that frequently occur here lead to an increase in the underwater level and thus to a reduction in the energetically usable fall height. For this reason, they are often removed by cost-intensive dredging, which represents a major intervention in the water and disrupts the bedload balance. As studies at six power plants in Mürz / Styria have shown, the underwater level can be significantly reduced by installing steering grooves and the associated local bottom depressions. Evictions and the associated negative effects can thus be avoided in the long term.

See also

Instream River Training

literature

  • Mende, M. Sohlnahe transverse structures for near-natural flow regulation , contribution to the 7th JuWi meeting, series of publications on water management No. 43, Graz University of Technology, 115-120, 2005 <
  • Mende, M. Lenkbuhnen: An inexpensive and natural method for upgrading rivers. Contribution to the joint institute colloquium of the TU Braunschweig and HS Magdeburg-Stendal (FH) on November 16, 2006, Inexpensive modules for the implementation of the EU WFD, 22-26, 2006
  • Badura, H. et al .: Planning, construction and monitoring of a flow funnel on the Mur. Hydraulic Engineering Symposium Graz 2006, Water Management Series, TU Graz, Volume 2, 2006
  • Sindelar, C. et al .: Monitoring of a bent training structure at the River Mur. Proc. of the Conference Hydraulic Measurements and Experimental Methods Lake Placid / USA. Book of Extended Abstracts, 118 - 123, 2007 (English)
  • NLWKN: Water Framework Directive Volume 2 - Guideline for planning measures for surface water - Part A: Flowing water hydromorphology. Recommendations on the selection, setting of priorities and implementation of measures for the development of Lower Saxony's rivers in 2008

Individual evidence

  1. ↑ Grober 1997
  2. ↑ Grober 1997, Badura et al. 2006, Sindelar et al. 2007
  3. ↑ NLWKN 2008
  4. ↑ Friedrich, J. Nature measurements on the functioning of groynes on the Mürz. Diploma thesis at the Institute for Hydraulic Engineering and Water Management, Graz University of Technology, 2008.

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