Lake Concordia (Zealand)

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Lake Concordia
Lake Concordia.JPG
Lake Concordia (June 2008)
Geographical location Saxony-Anhalt , Germany
Tributaries Königsauer See (overflow)
Places on the shore Nachterstedt , Schadeleben
Data
Coordinates 51 ° 49 '16 "  N , 11 ° 21' 0"  E Coordinates: 51 ° 49 '16 "  N , 11 ° 21' 0"  E
Concordia Lake (Seeland) (Saxony-Anhalt)
Lake Concordia (Zealand)
surface 3.5 km²
length 2.3 km
width 1.1 km
scope 6.7 km
Maximum depth 61 m
Middle deep 29.5 m

particularities

Flooded open pit

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The Concordia lake ( lat. Concordia " harmony ") is the largest artificial lake in the Harz foreland in Saxony-Anhalt . It is located about eight kilometers northwest of Aschersleben and borders directly on the districts of Nachterstedt in the south and Schadeleben in the north, which are part of the city of Seeland .

history

The remaining open pit in 1999

The name of the lake is derived from the former Concordia lignite mine . The flooding of the former Nachterstedt opencast mine , the largest remaining hole in the former lignite mining area in the Salzland district , which was initiated in 1996 , has created a lake that can be used in many ways as the center of a developing post-mining landscape , the Harzer Seeland leisure landscape . In the summer of 2002, Lake Concordia reached a surface of about 300 hectares. With an opening ceremony on August 17, 2002, the lake was officially opened for water tourism. Since May 25, 2005, a 250-person passenger ship , the Seelandperle, has been sailing on it regularly during the season . In the summer of 2009 the water area covered 350 hectares. It was the largest water body that could be used for tourism between Magdeburg and Kassel as well as Braunschweig and Halle (Saale) . The maximum water level should be around 103  m above sea level in 2020 . NHN and a water surface of 650 hectares must be reached. The year 2030 was named in 2019 as the new date for finally reaching the 103 m mark. The maximum depth of the lake will then be 61 meters.

bad luck

The site of the accident as seen from Schadeleben, July 2009
The accident site on Lake Concordia, summer 2012

On July 18, 2009 at around 4:40 a.m. in the area of ​​Nachterstedt, an approximately 350 by 150 meter wide strip of land fell into the lake. A semi-detached house , part of another semi-detached house and a section of the street with a viewpoint and information kiosk were torn down; the slipped earth mass is estimated at 4.5 million cubic meters. Three people died and 41 other people in the Am Ring settlement were left homeless.

The tidal wave pushed the excursion boat Seelandperle on the opposite side of the lake and the water level of Lake Concordia rose, which increased the area of ​​the lake. The entire sea area and its immediate surroundings were cordoned off and declared a disaster area for a few days because further earth collapses threatened.

root cause

The slipped site was part of an open pit dump from the time before 1926, which was released for building with private homes in the 1930s. It was initially suspected that unfilled stretches from the second half of the 19th century, when coal was still being extracted in civil engineering , could be the cause of the landslide. Settlement flow initially appeared to be the more likely cause . In 1950 and 1959, landslides caused by settlement flow had already occurred in the open-cast mine, whereby one worker was killed in 1959.

Three months after the landslide, the Lausitzer und Mitteldeutsche Bergbau-Verwaltungsgesellschaft (LMBV) has confirmed evidence of a small earthquake as the cause of the accident. An institute at the University of Leipzig registered a shock of 1.0 on the Richter scale six minutes before the first emergency call was received in Nachterstedt. This seismic event started the landslide. The center of the quake was outside the open pit. In an interview with the Mitteldeutsche Zeitung , Mahmut Kuyumcu, managing director of the LMBV, said that the earthquake registered at 4:42 a.m. was the beginning of a long chain of causes that led to the accident. The exact location of the quake has not yet been pinpointed, but it is outside the actual open-cast mine, possibly in the area of ​​the earlier lignite underground mining. He rules out a purely settlement flow, which was initially assumed, since the break-off edge is very stable and the gradual failure to be expected in the case of settlement flow did not occur. Due to the high stability of the demolition edge, the hopes of the residents of the closed settlement to be allowed to re-enter their houses are increasing. The earth tremor has been known for a long time. The State Mining Office of Saxony-Anhalt stated that this measurement probably documents nothing more than the collapse of the more than two million cubic meters of earth mass, but not a seismic event.

Even two years after the quake, it was not clear why the landslide took place. In the first half of 2011, extensive drilling and pressure sounding took place in order to clear up the accident and to reopen the lake for tourism. The lake is still closed because several areas of the shore could slide off. In 2012 the results of the investigations should be available and at least some areas should be released again.

In 2016 it was finally determined that the cause of the accident was not due to deliberate or negligent action. On June 29, 2016, another landslide occurred during renovation work, in which around 1.7 million cubic meters of earth slid off.

consequences

Southwest side of Lake Concordia in August 2020 with a view of the renovation work
Southwest side of Lake Concordia in August 2020 with a view of the renovation work

Based on the investigation of Lake Concordia, it was decided in 2013 that the lake would have to remain closed for another two years. The opening of the lake and bathing operations, which was initially planned for the 2015 season, was postponed indefinitely in 2014. In 2017, partial approval for 2019 was promised.

In July 2019, the north side of the lake at Schadeleben was reopened for tourism. Around 220 hectares of the lake area can be used again by bathers and water sports enthusiasts. The south side of the lake and the bank area outside the bathing area on the north bank remain closed.

Individual evidence

  1. ↑ Post- mining landscape Nachterstedt - Harzer Seeland (PDF; 3.6 MB) bwk-lsa.de. Retrieved August 2, 2010.
  2. ↑ Off to the water - summer vacation in Germany can be wonderfully wet , openPR , 7 July 2009
  3. ^ Lake Concordia. In: stadt-seeland.de. Retrieved on August 27, 2020 (NN no longer exists).
  4. ↑ Landslide from Nachterstedt 2009: Buried under 4.5 million cubic meters of earth: corpses remain missing In: mz-web.de , July 15, 2015, accessed on June 13, 2018.
  5. ^ Lutz Geissler: Maps of the Nachterstedt disaster. Geoberg.de, July 22, 2009, archived from the original on June 12, 2010 ; Retrieved August 2, 2010 .
  6. ↑ Landslide tears house at sea. Spiegel Online , July 18, 2009, accessed July 18, 2009 .
  7. ↑ Dwellings collapsed in the opencast mine ( memento from July 22, 2009 in the Internet Archive )
  8. ↑ 1959: Kippenrutsch - miners were in shock and panicked , Mitteldeutsche Zeitung , July 19, 2009
  9. ↑ Interview with the managing director of the LMBV , Mitteldeutsche Zeitung , September 25, 2009
  10. ↑ New note: earthquake triggered landslide , Mitteldeutsche Zeitung , July 25, 2009
  11. ↑ Landslide drama still not resolved. Welt Online , July 14, 2011, accessed August 18, 2011 .
  12. ^ Nachterstedt is put in the files. (No longer available online.) In: mdr.de. February 23, 2016, archived from the original on June 2, 2016 ; accessed on June 2, 2016 .
  13. ↑ Concordia Lake near Nachterstedt: Can I bathe again in 2019? In: mz-web.de. August 10, 2017, accessed June 13, 2018 .
  14. ^ Next Ebbe am Concordiaee , Neues Deutschland , July 10, 2013, accessed on February 24, 2014
  15. ↑ No approval in 2015 either: Broken dreams at Lake Concordia. In: Mitteldeutsche Zeitung. mz-web.de, accessed on February 23, 2016 .
  16. ↑ Regine Lotzmann: Partial release 2019 at the Concordiasee in Nachterstedt: Now there is another perspective. In: mz-web.de. August 12, 2017. Retrieved June 13, 2018 .
  17. ↑ Bathing start at Lake Concordia. In: mdr.de. July 13, 2019, accessed July 15, 2019 .
  18. ↑ Concordia See: Joint media information from the city of Seeland and LMBV In: lmbv.de , accessed on July 18, 2019 (with graphics of the released area)

Web links