Wildbach- und Lawinenverbauung in Bayern
Torrent and avalanche control in Bavaria

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Heft 159, August 2008, 72. Jahrgang

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Riedl Johannes

Verbesserung des Hochwasserschutzes in Garmisch- Partenkirchen – das größte Wildbachprojekt in Bayern

Sintflutartige Regenfälle führten Pfingsten 1999 insbesondere an der Kanker im Ortsteil Partenkirchen zu einer schweren Hochwasserkatastrophe. Am Wasserwirtschaftsamt Weilheim wurden im Rahmen der Vorplanung zur Verbesserung des Hochwasserschutzes mehrere Varianten untersucht Im Rahmen eines intensiven Planungsprozesses wurden 2 Varianten intensiv untersucht. Dabei wurden anhand eines Niederschlag-Abflussmodells die maßgeblichen Abflüsse in den einzelnen Gewässern und ihr zeitlicher Verlauf ermittelt. Daraus konnte eine aus verschiedenen Teilkomponenten bestehende vernetzte und damit auch optimierte Ausbauvariante entwickelt werden, die die Elemente Ausbau, Überleitung und Rückhalt umfasst. Durch den intensiven Optimierungsprozess konnte dabei sowohl der Umfang der Maßnahmen, als auch deren Kosten minimiert werden. Mit Baukosten von insgesamt ca. 25 Mio. € ist es das größte Wildbachausbauvorhaben in Bayern.

Improvement of flood protection in Garmisch-Partenkirchen – the greatest torrent control project in Bavaria

"Statistically Garmisch-Partenkirchen is swamped every 20 years by floods from the torrents Kanker, Partnach and Fauken. Efforts for flood protection started already more than 100 years ago. The protection works reached only a rather low protection level. After the disastrous flood in 1999 causing damages in a range of 25 million Euros and one casualty it became obvious, that a comprehensive flood protection was necessary. All variations of flood protection solutions were checked regarding to the costs between 25 to 40 Million Euros and also the feasibility in a very compact populated community. Based on a points rationing system a custom made solution was found by means of precipitation- discharge-models for the torrents in Garmisch-Partenkirchen. Due to the different sizes of the catchment areas, the geographical situation, the exposition and the elevation of the torrents consequently the peak discharges are variable as well as the decisive rain situations in the torrent catchments. These findings were used to develop a combined system consisting of an optimized discharge, a control of the distribution of the flood peak in the different torrents and a storage of the remaining flood maximum. It was not possible to install a retention basin for the flood maximum of the torrent Kanker with a required volume of more than 1 million m³. Moreover the different discharge capacity in the torrents in the settlement areas was optimized by a transition channel. In 2004 the project with costs of about 25 million Euros was started. It is the biggest torrent control measure in Bavaria (Germany) and will be tangent to many of very important infrastructure issues such as the reconstruction of the ski jump, some important traffic roads, the railway an the waste water disposal in Garmisch-Partenkirchen. The core part in the Kanker-Partnach-project is the transition channel which will be put in operation in summer 2008. The convincing idea of the solution for the flood protection for Garmisch-Partenkirchen is to use the fact that the peak discharge will not occur during the same precipitation situation in all 3 torrents at the same time. The total catchment area of all 3 torrents Partnach, Kanker and Fauken amounts to about 128 km² and consist of the following parts: • Partnach: 98 km²; high alpine character, elevation up to about 3000 mNN; length 21 km; situated in the south of Garmisch-Partenkirchen. • Kanker: 26 km²; length 9 km; strechted shape in an east-west exposition; elevation up to 1200-1300 mNN with an average gradient of 23% in the southeast of the community • Fauken: 4,4 km²; elevation up to 1780 mNN; length 4km; in the east of the area. The catchment areas of all torrents had been investigated considering the specific hydrological situation using a precipitation-discharge-model. The results showed some significant differences important for the proposed solution in the design flood with an occurrence of 100 years (HQ100): • Partnach: maximum HQ100 93 m³/s, 48 hours rain event; capacity 55 to 75 m³/s • Kanker: maximum HQ100 63 m³/s 12 hours rain event; capacity 10 to 23 m³/s • Fauken: maximum HQ100 24 m³/s; 3 hours rain event; capacity 24 m³/s In case of a 12 hours rain event, which is critical for the Kanker, the discharge in the Partnach is only 69 m³/s. Given that the Partnach is trained for a HQ100 there remains a reserve of at least 21 m³/s. This reserve is used by the transition of water from the Kanker to the Partnach. For the Kanker itself there remains a necessary capacity of only 13 m³/s which is possible without any construction measures. From exceeding discharge up to 30 m³/s will be diverted to the Partnach. If the flood discharge is even higher or the capacity of the Partnach will be exceeded the retention basin in the Kanker with a storage volume of 220.000 m³ will be activated. The transition channel connects the retention basin with the Partnach over a length of 1300 m. So the capacity of the bigger Partnach is fully used. Only from the confluence of the Fauken the Kanker has to be reconstructed with a subsurface channel to the Partnach with a higher discharge capacity. Referring to the design calculations this solution can master the design flood HQ100 in the 3 torrents Kanker, Partnach and Fauken."

Bei Fragen zu diesem Artikel wenden Sie sich bitte direkt an den Autor:
Riedl Johannes
WWA Weilheim
Pütrichstraße 15
82362 Weilheim