Sylvenstein Dam

Retrofitting: 1994-2004

The Sylvensteinspeicher, also Sylvensteinstausee or simply called Sylvensteinsee, is a reservoir in Isarwinkel south of Lenggries, on the road from Bad Tölz to Achensee. It was built in the years 1954 to 1959 for flood protection in the Isar valley. In dry periods, a sufficient water supply from the river Isar is secured since 1990, the military Krüner a residual flow of at least four cubic meters per second is guaranteed for ecological reasons.

Description

Two hydropower plants on the dam are used for energy production. 1994 to 2001, the dam was increased by three meters to extend the flood protection. Already at Pentecost flood of 1999, the dam increase and the second spillway tunnel with the temple-like intake structure and with a capacity of up to 400 m³ / s could prove. When even stronger Alpine floods of 2005 had to be re-opened in the afternoon of August 23, 2005, the lock, as the limit of the capacity of the Sylvensteinspeichers was reached.

The height of the dam itself is 44 meters, the length of its dam 180 m. The dam dams beside the River Isar their side inflows Duerrach (southern arm) and Walchen (eastern arm) on. The Isar and Duerrach carry large amounts sediments and sedimentary rocks with you, which will fill the reservoir in the coming decades. For the wild river Isar, the " taming " means a loss of habitat for specialized animal and plant species - especially in high water - again and again through the water migrated gravel banks. Particularly striking is this anthropogenic alteration of the ecosystem in the river landscape Pupplinger Au at Wolfratshausen, where in the past 50 years, the floodplain has significantly spread to formerly open gravel surfaces.

The lake was named after the Sylvenstein, a natural constriction in the upper Isar Valley with its impressive bridge a commonly imaged subject against the backdrop of the Karwendel Mountains. Sunk in the lake is the former village case, which was demolished before the flood and rebuilt a few dozen meters higher on the road to Vorderriß. Due to the natural attractiveness of Sylvensteinsee is today a popular tourist destination and a recreation area.

History

Reasons for building

In the first half of the 20th century, the Isar was withdrawn at the top of more and more water. So, in order to increase the performance of 1924 went into operation Walchensee power plant, the Isar redirected on Krüner military largely in the Walchensee. Since 1949, in addition to the Rißbach, which formerly flowed into the Isar, derived through long tunnels in the Walchensee. Originally also the Achensee dehydrated over the ache in the Isar. The construction of the Achensee - hydro power plant in Jenbach in 1927 the Isar also this water supply (and also the Duerrach, which is derived in the Achensee ) because the lake from then on, primarily through the power plant in the 380 m deeper Inn has been withdrawn, is derived. The Isar was so in the upper part becoming the flow body, particularly in times of drought, the water level fell more and more, so that it required an urgent ENHANCE the situation - especially for the town of Bad Tolz, the most suffered from the lack of water. Therefore, it was finally begun with the then highly controversial construction of Sylvensteinspeichers to achieve a more constant water level of the river Isar. The additional guaranteed flood protection, however, was only a secondary objective. Originally the lake was planned much larger and should reach Vorderriß.

As occurred catastrophic flood in June of 2013 in many parts of Bavaria, the Sylvensteinstausee was filled to the brim. The water was 13 feet higher than normal. When Wasserwirtschaftsamt one spoke of " landing point ". Would have received on June 3, even more water, the reservoir would have to give more water, which would have increased the downstream water level. Tobias Lang, Head of dams in the Water Management Office, said, would currently 225 cubic meters per second drained. It will remain in the coming days in order not to aggravate the flood situation in Lower Bavaria. Thanks to the reservoir lake and the flood protection measures taken in recent years in Bad Tolz has not taken place in the region to disaster on the Isar, said experts.

Modernization measures

Between 1994 and 2001 extensive modernization measures were carried out. Here, a dam control system was installed, erected a second spillway and increased the dam to increase the flood control space. In addition, a second power plant was built. The new plant has a compact axial turbine with a capacity of 3.8 MW. Thus, a standard capacity of 20 million kWh can be achieved.

Despite this extensive modernization measures 2011 more exercise activities are carried out since July. In this case, an additional sealing wall as well as an improved monitoring system for detecting and leachate are installed. The cost of the estimated five-year construction of around 25 million euro bears the Free State of Bavaria.

Specifications

Power Plant I ( since 1959), rebuilt in October 2004:

Power Plant II ( since 2000)

Dam

The dam is a geschütteter of gravel, rubble and sand dam with a central core of seal Erdbeton (75% gravel, 8% fine sand, 17% silt and low Bentonitanteile ). It stands on a over the times with boulders filled from the River Isar, up to 100 m deep gully that was flowing through groundwater. Before could be started with the construction of the actual dam, so first had this groove pressed and thereby a 5,000 m² sealing skirt are introduced to seal the valley and below the visible dam with a clay / cement / water glass suspension.