Salty lake

Salty lake
Panoramic image of the Salziger See area in the aerial view from the northeast with Kernersee on the left, Bindersee on the right and areas that have fallen dry; on the right in the background the sweet lake
Geographical location	Mansfeld-Südharz district near Röblingen
Tributaries	Weida, Salzke
Drain	Salzke
Data
Coordinates	51 ° 28 '17 "  N , 11 ° 43' 23"  E Coordinates: 51 ° 28 '17 "  N , 11 ° 43' 23"  E
surface	8.5 km² (originally)
particularities	Is currently still being pumped out and is therefore mostly dry at the moment.

The Salzige See was one of the Mansfeld lakes southeast of Eisleben , in what is now the district of Mansfeld-Südharz in Saxony-Anhalt . In the early Middle Ages, the water surface reached only slightly interrupted from near the gates of the city of Eisleben from the Faulen See via the Süßen See and the Salziger See to the Langenbogen ponds . Since the drainage, the Bindersee and the Kernersee are still water-bearing parts of the former standing water.

The area of ​​the lake from originally 850  hectares (around 8.5 square kilometers) decreased rapidly by 300 hectares in the years 1892/93. It lost more than 4 meters of its depth in the summer of 1893 alone. 30 million cubic meters of lake water dried up in the underground passages that had become free. The salty lake was drained to prevent the mining industry from being endangered by falling water. Since mining was shut down and dewatering ceased in the 1970s, the groundwater has gradually increased again and from 1985 onwards reached the level of the deepest areas of the former seabed. The wet areas have led to individual lake areas that today cover around 15 percent of the former lake area.

geology

At the deepest point of the Eisleben lowland , the Mansfeld Lakes formed around 8000 years ago. There are various hypotheses about the formation of the lowland and the lakes:

• Deep boreholes to investigate the copper shale showed that there is an extensive and massive mass of rock salt in the subsurface of the lake area as far as Eisleben. The large amount of water lost through salt leaching in the depths caused a lowering of the rock salts on top of it and thus caused the formation of a hollow shape on the surface. The leaching and the subsidence it causes are limited to the area of ​​the salt level. This runs fairly uniformly from Eisleben to Wansleben at 145–150 meters below sea ​​level , i.e. about 225 meters below the dry soil of the former salty lake, created by underground leaching of the formerly high upper part of the salt mass. The valley basin of the Mansfeld Mulde was created by subsidence as a result of salt leaching.
• The sweet and salty lakes are remnants of earlier rivers, as the regular channel-like depressions of the lakes speak for. Probably the Unstrut from the influence of the helmets turned to what is now the Mansfeld region, flowed through the depression now occupied by the Salty Lake and reached the Saale in today's Salzabett . In the rubble of the lake and the Salza you can find stones that come from the Thuringian Basin and could not have been brought in by the current waters. When the Hornburger Sattel and its neighboring heights rose, the Unstrut's previous drain was blocked so that it created a new mouth through the Freyburger Tal.

Effects of mining

In the continuous flow of water from the western edge of the Mansfeld Mulde into the rock salt seam of 1000 meters thickness and the constant movement of water (up to 30 brine springs ), humans intervened through mining. With the deepening of the copper ore mining, the drainage measures were strengthened, the circulation path of the water was built under, so that vertical connections were created between the mines and the water circulating in the rock, which resulted in catastrophic water inrushes in the pits.

The Mansfeld trade union , which is responsible for 17,000 miners and their 40,000 dependents, acquired the right to artificially remove the salty lake in order to prevent the shafts from being endangered by any inrushing water. In January 1894 the lake basin was completely drained, so that the wells in the villages dried up, mill streams and riparian zones silted up and the population of the entire lake area suffered from the general lack of water. The entire natural receiving system of the lake had to be changed. The larger tributaries were led in a northern and southern ring canal around the lake area, small tributaries in open trenches to the pumping station. The southern ring canal supplied the villages of Erdeborn , Röblingen and Amsdorf , the Wilhelmine and Laura mines near Oberröblingen and the Amsdorf coal and steel works .

The new land area offered space for agriculture at the beginning of the 20th century and was also used for the sinking of potash shafts and as storage pits for the coal industry. The drainage of the lake only had a minor impact on the water released to the subsoil. The natural springs formerly present in the lake area acted like sinkholes for the lake water. The vertical connections in the depths were preserved after the lake was drained. This is shown by the water losses in the Bindersee in 1961 and 1968.

Since the final cessation of mining in 1981, water has been diverted via the key tunnel. The water flow partly goes back towards the lake area. The hydraulic equilibrium has been restored: if the amount of salt water runoff over the key tunnels were reduced, the water in the lake area would rise more rapidly.

Historical

In the book The Preservation of the Mansfeld Lakes , Wilhelm Krebs describes the landscape:

“There is a chain of three lakes there. The northernmost, the Sweet Lake , fills its elongated basin on a floor level five meters higher than the other two. So far, through two stream beds, it has had the opportunity to release an excess of its tributaries to the two southern lakes. These were connected by a wide canal. The middle one, the Bindersee, appeared only as an appendage of the larger, the Salziger See, which earlier, what it received as a surplus, especially from the Weida flowing in from the south, also in turn to the Bindersee and through it to the common drainage, the Salzke , gave. This river approaches the Saale near Salzmünde and is said to have been the final course of the Unstrut , which now flows further south , in the Diluvium , so that in the Salziger See you can see the considerable remnants of an old dammed Unstrut course . This largest lake, about three times the size of the sweet one, ten times the size of the Bindersee, was, due to its abundance of water and the salt content, which until recently corresponded to its name, was considerable enough to induce the Leipzig doctor Franke to found a bathing company on shares in 1850 ... "

Perspectives

Remaining areas of the lake and the L176 near Röblingen, which runs through the lake basin from south to north

The state government of Saxony-Anhalt decided at the beginning of 1995 to support the process of the re-creation of the salty lake. This support is expressed in the continuous provision of funds (1996–1998 a total of 11.3 million marks ) and the start of work by the development company Seengebiet Mansfelder Land mbH, which was founded especially for this project.

The re-emergence of a disappeared lake with an area of ​​around 850 hectares after more than 100 years affects national cultural, economic, organizational, legal, social and financial issues. The project includes changes to conditions that have now become manifest, such as the character of water bodies including the groundwater area, landscape and nature design as well as land uses and infrastructures.

In April 2012, the NABU Foundation for National Natural Heritage received from Lotto Sachsen-Anhalt a grant of 75,000 euros for the acquisition of nature conservation areas in the “Salziger See” area. This will finance the construction of a 470 hectare new nature reserve.

literature

• Wilhelm Krebs: The preservation of the Mansfeld lakes, Gustav UHL Verlag Leipzig, 1894

See also

• List of nature reserves in the district of Mansfeld-Südharz

Individual evidence

1. ↑ Welcome to the Mansfeld Lakes ( Memento from September 4, 2012 in the web archive archive.today )
2. ^ Structure of the NABU protected area “Salziger See” , NABU press release of November 13, 2012, accessed on April 22, 2016.