Sinking of the Danube

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Sinking points of the Danube near Immendingen

The Danube sinking (also known as the Danube infiltration ) is an incomplete underground river tapping of the Upper Danube . Between Immendingen and Möhringen and near Fridingen ( Tuttlingen district ), water from the Danube seeps into the river bed at various points. The main sinking point is at the Gewann Brühl between Immendingen and Möhringen, around river kilometer 2755. The area is part of the Upper Danube Nature Park .

The term sinking is preferred because the water does not spread (seeps away) into the ground, but flows away in underground cavities as a directed stream. It is an underground bifurcation because a portion of the river on the Black River Danube , the European watershed passes through, a source in the Aach its way back to and over the Lake Constance , the Rhine into the North Sea flows.

Hydrography

Sinking points with a schematic route to the Aachtopf

The Danube water tapped from the sinking disappears in a karst water system of the well- stratified limestone formation of the White Jura (ox2) and emerges again in the fuzzy, lying bench limestone of the White Jura (ki 4) in the Aachtopf around twelve kilometers away . It then flows into Lake Constance as the Radolfzeller Aach near Radolfzell . Thus part of the Danube water also flows into the Rhine . This geographical situation is a distinctive feature of the large European watershed , which separates the catchment areas of the North Sea and the Black Sea .

Schluckloch on the southern bank of the Danube, at the main sinkhole below Immendingen

Since the water flows off through a large number of small to very small cracks and fissures, karstification at these points is still at an early stage of development. The subsequent cave system up to the Aachtopf, i.e. the subterranean branch of the Danube, is probably already well developed. This results from the close temporal correlation between the water temperatures of the Danube and the Aach spring, which suggests an underground river rather than a ramified system of rifts.

In the 1960s, Jochen Hasenmayer discovered and explored the first 400 meters of a large gorge-shaped spring cave, the Aach cave, from the Aachtopf . His research ended at a buried spot where no further progress was possible. Further exploration of the cave system has been ongoing since the 1980s as part of a private initiative. For this purpose, a sinkhole in the mountainous region between the Danube and Aachtopf has meanwhile been developed, which enables access to the water-bearing layers.

history

If the Danube is completely submerged , the bed of the Danube falls completely dry

The first historically documented complete sinking took place in 1874. Since then, the number of sinking days per year has risen sharply on average, albeit with small outliers. While measurements from 1884 to 1904 showed an average of 80 days of full immersion per year and the year 1921 holds an unbroken record with 309 fully immersed days, only 29 days were measured in 1922, but again 148 days in 1923. From 1933 to 1937 the number increased to 209 and from 1938 to 1945 to 270 days.

The connection between the sinking of the Danube and the Aachtopf was demonstrated on October 9, 1877 when the geologist Adolph Knop from the Technical University of Karlsruhe added 10 kilograms of sodium fluorescein , 20 tons of salt and 1200 kilograms of shale oil to the water in the Danube sinking . 60 hours later, all three substances appeared in the Aachtopf as "splendidly glowing green" salt water with a distinctly creosote-like taste . The connection between individual sinking points was later explored. In 1908, for example, a shaft was dug in Fridingen in order to find out through experiments where the water from this sinking drained.

In 1927 a smoldering dispute about the quantitative impairment of the Danube water was fought before the State Court for the German Reich between the states of Württemberg and Prussia as rulers of the Hohenzollern Lands on the one hand and the state of Baden on the other, which became known as the Danube sinking case .

outlook

Sign near Immendingen

How the karstification will develop on the sinking sections in the future cannot be precisely foreseen. The subterranean Danube removes around 7000 tons (2700 cubic meters) of lime from the karst system of the Aachtopf every year. Expansions or collapses in the underground system are conceivable in the near future, recognizable above ground by sinkholes or new ponors (swallowing holes).

In the long run, today's upper Danube will probably be completely diverted to the Radolfzeller Aach , and thus to the river system of the Rhine . Then the now insignificant tributaries Krähenbach (in Möhringen ) and Elta (in Tuttlingen ) would become the new source rivers of the upper Danube, which, however, already carries less water than the Iller, which flows into Ulm . Perhaps a similar stream capture has the ancient Danube (in this section Feldberg Danube called) in the Würm even further upstream, today Wutach knee in Blumberg , experienced.

Interventions

The seepage points are bypassed via several tunnels. In Fridingen, the Danube and the Bära drive the Fridingen hydropower plant . At the weir, the water is diverted through a 1.4 kilometer long tunnel at the eastern end of the tunnel of the Tuttlingen – Inzigkofen railway line ( 48 ° 2 ′ 9.47 ″  N , 8 ° 57 ′ 24.39 ″  E ) for the eleven kilometers bypassed the long Fridinger Danube loop including the sinkhole there.

documentation

  • The black Danube: a river disappears . Documentation directed by Axel Nixdorf on behalf of ZDF in collaboration with Arte , Bewegungste Zeiten Filmproduktion GmbH, 50 minutes, Germany 2009. German premiere on April 29, 2010 on ARTE.

Web links

Commons : Donauversinkung  - Collection of pictures, videos and audio files

Individual evidence

  1. ↑ At about 47 ° 55 '52.3 "  N , 8 ° 45' 46.6"  O .
  2. ↑ Hans Binder , Herbert Jantschke: Höhlenführer Schwäbische Alb . 7th edition, 2003, ISBN 3-87181-485-7 , p. 260.
  3. ↑ Hans Binder, Herbert Jantschke: Höhlenführer Schwäbische Alb . 7th edition, 2003, ISBN 3-87181-485-7 , p. 261.
  4. ↑ A. Knop (1878): About the hydrographic relationships between the Danube and the Aach spring in the Baden Oberland. In: New Year Mineral. Geol. Palaeontol. Pp. 350-363.
    H. Hötzl (1996): Origin of the Danube-Aach system. In: Environmental Geology. Vol. 27, No. 2, pp. 87-96. doi : 10.1007 / BF01061676 .
  5. ↑ Holding Ho 235 T 11-12 No. 677 on Landesarchiv-BW.de.
  6. ↑ StGH RGZ 116, appendix p. 24.
  7. ↑ www.windkraft-journal.de .
  8. ^ Karl Falko Hahn: Danube loop supplies electricity . In: Südkurier of December 2, 2005.

Coordinates: 47 ° 55 ′ 56 ″  N , 8 ° 45 ′ 49 ″  E