Weir Oberföhring

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Weir Munich-Oberföhring, Oberwasser (south side)
Inlet structure of the Middle Isar Canal, underwater
Operating building of the new, underground power plant

The Oberföhring weir is a weir system on the Isar in the north of Munich and at the same time the inlet structure of the Middle Isar Canal . However, the weir itself is not a hydroelectric power station . But there is a small, largely underground power plant immediately below the weir, through which water from the canal is returned to the Isar.

location

The weir connects the northern part of the English Garden with the Oberföhring district east of the Isar . It is the first structure on the Mittlere-Isar-Kanal , which begins there and flows back into the Isar after 64 kilometers just above Landshut . The weir and the first 54 km of the canal belong to Uniper Kraftwerke GmbH , a subsidiary of Uniper , and the last few kilometers to the Uppenborn works of Stadtwerke München , which explains the different lengths.

function

The Oberföhring weir serves to dam the Isar by around 6 m and to drain most of its water into the Mittlere-Isar canal in order to drive the power station staircase, which consists of seven run-of-river power stations, with a total gradient of around 109 m. Of this total gradient, 88 m is attributable to the E.ON Wasserkraft power plants and 21 m to the two Uppenborn power plants.

Pedestrians can cross the Isar via a wide footbridge on the north side of the building or reach the "Isarinsel Oberföhring" leisure area between the Isar and the Mittlere-Isar Canal.

Building

Weir

The weir consists of the light beige painted building lying across the Isar with the weir system and the inlet structure arranged at an angle of 45 °.

The building spans a clear width of 78.5 m with four arches, each 17 meters wide and around 5.7 meters high. It is supported by three pillars, 3.5 m wide, reaching far into the underwater, each of which offers pedestrians a small viewing platform.

The simple brick construction, plastered and covered by a hipped roof building is founded on a concrete slab that connects below the headwater to an approximately 14 m deep concrete transverse wall, which consists of a caisson founded by compressed air, which extends down to the solidified Flinz . The horizontal foundation slab continues in the underwater 45 m after the gate wall or 31 m after the end of the pillars and is then closed by a 9 m deep iron sheet pile wall.

The steel rifle boards with a height of 5.65 m can be raised by motors or hand cranks, which are housed in the house-like superstructure. There is also an overhead traveling crane in the building, which can also operate the stop logs stored there, with which the weir can also be closed.

The inlet structure with a clear width of 46.6 m was built at an angle of 45 ° to the river axis in order to reduce the penetration of gravel and sand into the canal. It can be done by eight per 5.5 m wide contactors are completed. Rinsing channels are arranged under the inlet of the canal at an angle towards the Isar, so that their water is fed back into the underwater via a triangular clarifier between the weir and the inlet.

Oberföhring power plant

The canal can hold up to 150 cubic meters of water per second, which has repeatedly resulted in the Isar hardly carrying any water on the route to Moosburg . Since E. hydropower has committed to at least a residual amount of water to leave of 15 cubic meters per second on average in der Isar, this water is returned from the channel into the Isar and assisted by a small water power station with a Kaplan turbine with a MW power used . Above ground, only a small machine house of the power plant can be seen on the northeast side of the weir.

history

Aerial view of the plant

From 1896 until the construction of the weir, a cable ferry was operated at this point . Even before the First World War there were plans to use the slope of the Isar between Munich and Moosburg for power generation after the municipal power plants in Munich in 1907 that of Friedrich Uppenborn initiated Uppenbornwerk had commissioned. Mittlere Isar GmbH began planning the canal in 1918 under the direction of Theodor Rümelin . In 1919, the planning passed into the possession of the Bavarian state, which began construction work to combat unemployment. Mittlere Isar AG , founded in 1921, then took over the project and completed the weir in Oberföhring by 1924. During this time, the four concrete arch bridges were also built that connect Oberföhring with the headland called Isarinsel formed by the canal . The weir and these bridges survived the Second World War , as the whole of Munich was prevented from being blown up before the American invasion. The bridge at St. Emmeram was replaced in 2003 by a modern reinforced concrete structure.

In 2002, the Free State of Bavaria and E.ON Wasserkraft agreed to increase the amount of water remaining in the Isar to the current level of 15 m³ / s, as well as its use by a new power plant to be built on the weir; this should also improve the ecological conditions on the Isar between Oberföhring and Moosburg. In the following years the weir was renovated. The power plant went online in 2008; it generates 5.7 million kilowatt hours of electricity per year, the power plants on the Mittlere-Isar canal a total of about 430 million kilowatt hours. A new fish ladder has been built next to the power plant since 2012 .

Individual evidence

  1. ↑ In BayernViewer, the height of the headwater of the Oberföhring weir is given as 500 m, that of the Moosburg compensation pond as 411.9 m and that of the Isar at the mouth of the canal as 390.5 m.
  2. ^ A b c d e E. Matern: Die Wasserkraftanlagen in Bayern III, Die Mittlere Isar In: Zentralblatt der Bauverwaltung , 43. 1923, S. 241-252, S. 242 f.
  3. ↑ Explanatory board on the weir

literature

  • Karin Bernst: Today's Isar bridges in the north of Munich . In: Association for District Culture in the Munich Northeast e. V. (Ed.): The bridge at Sankt Emmeram. With contributions by Karin Bernst, Karl Höferle, Roland Krack. For the inauguration of the new pedestrian bridge over the Isar near St. Emmeram on May 13, 2005 . Verlag NordOstKultur, Munich 2005, p. 17-27 .
  • Manfred Nerdinger (Ed.): Architecture Guide Munich . Reimer, Berlin 2002, ISBN 3-496-01211-0 .
  • Christine Rädlinger : History of the Munich bridges . Ed .: City of Munich, Construction Department. Verlag Franz Schiermeier, Munich 2008, ISBN 978-3-9811425-2-5 .

See also

Web links

Commons : Stauwehr Oberföhring  - Collection of images, videos and audio files

Coordinates: 48 ° 10 ′ 8.1 ″  N , 11 ° 36 ′ 59 ″  E