Gschliefgraben
Coordinates: 47 ° 53 ′ 1 ″ N , 13 ° 49 ′ 18 ″ E
| Gschliefgraben | |
|---|---|
| description | Debris cone |
| location | Near Gmunden (Upper Austria) between Grünberg and Traunstein |
| length | 3 km |
| width | 1 km |
| Events | severe landslides approx. every 100 years |
The Gschliefgraben is located on the eastern bank of the Traunsee in the Upper Austrian Salzkammergut . Between the 984 m high Grünberg and the 1,691 m high Traunstein , the Gschliefgraben extends over a length of three kilometers and a width of one kilometer. The Gschliefgraben became known through landslides and mass movements of rubble .
Due to its long history, the Gschliefgraben has been the subject of numerous geological studies. The name comes from the colloquial word 'slept' (slide, slide). There are numerous records of the moving cone of rubble that has already pushed many houses into the Traunsee.
History of exploration
The scientist Ami Boué first noticed the special geological conditions of the Gschliefgraben in 1832. Edmund von Mojsisovics and Urban Schlönbach reported in 1864 about inconsistencies in the rock sequence there . They found that between the flysch rocks of the Grünberg and the limestone of the Traunstein there are tertiary rocks from the Eocene . This finding contradicts the normal stratigraphic structure.
In 1983, the geologist Siegmund Prey of the Federal Geological Institute examined the Gschliefgraben and found that it was a tectonic window of the ultrahelvetic between the Rhenodanubic and the chalk stones . The exposure of the rocks of the window goes back to tectonic movements and millennia of erosion .
Claims
People have always used the Gschliefgraben as a settlement area. However, there were landslides there at regular intervals; again and again houses and cultivated land were pushed into the Traunsee. The records of landslides and rock avalanches date back to 1460, when cultural grounds, residential and farm buildings were devastated on the rubble cone. In 1700 part of the debris cone sank in the Traunsee and left a small bay.
The last natural disaster occurred in 2007/2008. 3.8 million cubic meters of earth moved towards Lake Traunsee. The earth masses destroyed a third of the Gschliefgraben; for twelve houses there was a risk of being pushed into the Traunsee. The torrent and avalanche control , an agency of the Ministry of Life, launched a renovation concept in 2007/2008 with a planned duration of around ten years, the cost of which was estimated at around 10-15 million euros. The state of Upper Austria supports these measures financially.
Damages from the 15th to 17th centuries
Records of damage in the Gschliefgraben go back to the 15th century. Around the year 1460 landslides took place in the area of the Gschliefgraben and damaged the houses and farm buildings there. There are no records of damage in the Gschliefgraben from the 16th century.
Between 1630 and 1634, the logging of firewood in the Gschliefgraben was forbidden by the Kk Forest Directorate. Another landslide occurred between 1660 and 1664. Triggered by a rock avalanche, the Gschliefgraben began to move in the direction of the Traunsee and sank the Harschengut farmhouse in the Traunsee.
Damage cases from the 18th to 19th centuries
Around 1700 an earth current caused a landslide in the Gschliefgraben and parts of the debris cone sank in the Traunsee. Approx. 30 years later, in 1734, an earth current pushed several houses and grounds into the Traunsee. Due to the logging for the salt economy of the Habsburg emperor in the area of the densely wooded Gschliefgraben, there was increased damage and landslides during this time. In 1860 there was a murmur slide in the area of the Liedringgraben in the upper part of the Gschliefgraben. In 1884 and 1891, the Gschliefgraben main earth current was dammed back by rock avalanches.
Damages in the 20th century
The first disaster in the 20th century occurred in the Hoisn area in 1910 . A number of forest and fruit trees were destroyed by a 10-15 meter earth current; the cultivated land was destroyed. In 1920 and 1947 the Gasthaus Ramsau was damaged by earth and Mur currents.
In 1955, the Gmundner campsite, which at that time was on the east bank of the Traunsee, below the Gschliefgraben, was buried by a one-meter-thick flood and 22 years later covered again by a 2.5-meter-thick flood. The campsite was then closed and re-established in another location.
Gschliefgraben landslide 2007/2008
The last major landslide took place in 2007/2008. According to a tip from geologist Dr. Johannes Weidinger, examinations were carried out in Gschliefgraben in 2004. They revealed that another landslide was imminent. Due to tectonic movements and years of seepage of water into the ground, the soil began to slide again towards Lake Traunsee. The movements reached a depth of 20 meters. Four million cubic meters of earth threatened twelve residential buildings and gastronomic objects. The danger area of the Gschliefgraben extends on the Traunsteinstrasse Unterm Stein in Gmunden from the Ramsau inn to the south to the Traunsteininstieg Herndlersteig . In 2007 the residents were evacuated within this area; Entry was prohibited during the critical phase.
The Gschliefgraben became a major construction site; Geologists tried to stop the landslides. The torrent and avalanche control (WLV) began with a renovation project to avert the impending disaster and invested in stabilization measures. The residents of the threatened houses had to be evacuated and the Gschliefgraben was declared a danger area.
As early as 1900, Adalbert Pokorny had drafted a redevelopment plan for the Gschliefgraben, which provided for the slippery area to be built with canals. This plan was revised in 2008 and adapted to the technical possibilities of the 20th century. Canals ten meters deep and eight meters wide were laid along the Gschliefgraben. They allow water to run off, which also endangers the Gschliefgraben. The renovation work is still in progress, but the landslide has been stopped (as of 2010).
Remedial measures
Numerous renovation measures have taken place in Gschliefgraben over the years. The goal was to stop the landslides and to enable life in the Gschliefgraben without danger.
After a rock avalanche in 1884, the Kk Oberförster Höller observed the slide area around the Gschliefgraben and seven years later the Kk Agriculture Ministry commissioned the torrent and avalanche control (WLV) to investigate the Gschliefgraben and its slide dynamics. In 1894, Professor Gustav Adolf Koch issued the first geotechnical report in which he proposed a drainage system in the Gschliefgraben. The WLV then worked out a plan for draining the Gschliefgraben.
In 1897 the Traunsteinstraße was built from the Gmundner Seebahnhof to the Traunstein. The first records of remedial measures go back to 1630. The Kk Forstdirektion imposed a ban on the procurement of firewood and construction wood in Gschliefgraben. In 1910 the Liedringbach was dammed to prevent a landslide in the Ramsau area. The existing forest in the slide area was rededicated as a ban forest. From 1961 to 1976 the Gschliefgrabenbach was provided with 21 concrete barriers. From 1974 to 1983, the erosion process in the Gschliefgraben could be partially contained with the help of a drainage system and forestry measures .
The largest rehabilitation measure in the history of the Gschliefgraben has been underway since 2007. The torrent and avalanche control developed a concept for the rehabilitation of the Gschliefgraben, the project will take 10 years and cost around 10-15 million euros. The WLV receives support from the state of Upper Austria, which is funding the renovation work.
Landslide remedial measures 2007/2008
The landslide in Gschliefgraben began on November 28, 2007, when strong mass movements occurred. From that day on, the Gschliefgraben was declared a disaster area. A crisis team, which consisted of the mayor of Gmunden, the district authority of Gmunden and the torrent and avalanche control, decided on the first immediate measures. Around a hundred people from 55 houses had to leave the disaster area and Traunsee-Ostuferstraße was closed to public traffic. There has been a construction ban in the danger area since 1974. The aim of these measures was to relieve and stabilize the alluvial cone in Gschliefgraben and to protect the population living there. The torrent and avalanche control, which set up an early warning and monitoring system, is responsible for the implementation and coordination of the construction measures.
The following immediate measures were carried out:
- Discharge of 10,000 tons of water per day from the slide area
- Removal of 160,000 m³ within the first seven months
- Logging on 22 hectares to carry out the renovation measures
- Construction of 220 drainage wells
- Constant evaluation of the measures introduced
As a result, some renovation measures are still necessary to defuse the Gschliefgraben. Several cubic meters of earth still have to be removed from the Gschliefgraben in order to relieve the slope; Drainage and flood protection measures are to be ensured by building further drainage ditches and drainage channels.
The reforestation of the Gschliefgraben is another important part of the rehabilitation measures. The aim of setting up the early warning and monitoring system is the immediate evacuation of the residents of the Gschliefgraben in the event of a disaster. This is guaranteed by refraction measurements , core drilling, soil investigations and numerous other geotechnical measures.
The renovation measures will take about ten years and are expected to cost 11.5 million euros, the insurance damage, however, would amount to around 30 million euros - since the renovation project only costs a third of that, those responsible have decided to renovate the Gschliefgraben . The work was divided into three levels of urgency:
| Urgency level | Period | Cost in millions of euros |
|---|---|---|
| I. | 2008-2009 | 5.0 |
| II | 2010-2014 | 4.0 |
| III | 2015-2017 | 2.5 |
literature
- P. Baumgartner: Earth and rubble flows in the Gschliefgraben near Gmunden am Traunsee (Upper Austria) - On geology, formation, development and restoration . In: Communications from the Society of Geology and Mining Students in Austria . tape 27 . Vienna 1981, p. 19-38 .
- M. Jedlitschka: Analysis of mass movements in weathered blankets on flysch and marl and their stability improvement using the example of the Gschliefgraben near Gmunden . Ed .: University of Natural Resources and Life Sciences, Vienna. Vienna 1990, p. 1–158 (unpublished dissertation).
- Torrent and Avalanche Control in Austria, Forestry Service for Torrent and Avalanche Control, Upper Austria Section, Regional Construction Management Salzkammergut (Ed.): Gmunden Danger Zone Plan (1st revision), Gmunden municipality, Gmunden district . 2000.
- Johannes Weidinger: The Gschliefgraben slide area on the east bank of the Traunsee (Gmunden / Upper Austria) - a millennia-old field of tension between man and nature . In: Yearbook of the Federal Geological Institute . tape 149 , issue 1, 2009, ISSN 0016-7800 , p. 195–206 ( opac.geologie.ac.at [PDF]).
- Robert Marschallinger, Christoph Eichkitz, Harald Gruber, Kathrin Heibl, Robert Hofmann & Korbinian Schmid: The Gschliefgraben Landslide (Austria): A Remediation Approach involving Torrent and Avalanche Control, Geology, Geophysics, Geotechnics and Geoinformatics . In: Austrian Journal of Earth Sciences . tape 102/2 . Vienna 2009 (English, univie.ac.at [PDF; accessed April 4, 2013]).
Web links
- Geographical map of Gschliefgraben
- For the horizontal and vertical structure of the earth and debris flow cone of the Gschliefgraben on the Traunsee near Gmunden. biologiezentrum.at
- Expert excursion in Gschliefgraben. ( Memento from February 22, 2015 in the Internet Archive ) forstnet.at
- Current research area: Gschliefgraben. baunat.boku.ac.at
- Gschliefgraben active again. ( Memento from June 25, 2009 in the Internet Archive ) im-salzkammergut.at
- Safety measures after a massive slope slide in the Austrian Gschliefgraben. gps-bau.com
- Weather monitoring ( memento of May 7, 2010 in the Internet Archive ). blueskywetter.at
Individual evidence
- ↑ E. v. Mojsisovics and U. Schlönbach: The behavior of the flysch zone to the northern edge of the limestone Alps between the Traun and Laudachsee near Gmunden . In: Negotiations of the Geological Reichsanstalt . 1868, p. 212-216 .
- ↑ a b Weidinger 2009, p. 196 ff.
- ↑ Geologische Bundesanstalt (Ed.): On the development of mass movements in the Gschliefgraben . S. 2 .
- ↑ Weidinger 2009, p. 198.
- ↑ a b Weidinger 2009, p. 197.
- ↑ a b Weidinger 2009, p. 197 f.
- ↑ a b c Weidinger 2009, p. 202.
- ↑ Forstzeitung Special 6/2009, p. 16.
- ↑ Disaster tourism in Gschliefgraben on orf.at of April 28, 2010, accessed on October 31, 2010.
- ↑ Die.Wildbach and Avalanche Control (Ed.): 200 days Gschliefgraben .