Hirschler pond
| Hirschler pond | |||||||||
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| Coordinates | 51 ° 47 '44 " N , 10 ° 22' 12" E | ||||||||
| Data on the structure | |||||||||
| Lock type: | dam | ||||||||
| Construction time: | 1660 | ||||||||
| Height above valley floor: | 11.40 m | ||||||||
| Height of the structure crown: | 588.78 m above sea level | ||||||||
| Crown length: | 414 m | ||||||||
| Data on the reservoir | |||||||||
| Altitude (at congestion destination ) | 587.43 m above sea level | ||||||||
| Water surface | 16 ha | ||||||||
| Total storage space : | 599,000 m³ | ||||||||
| Catchment area | 0.89 km² | ||||||||
| Design flood : | 0.77 m³ / s | ||||||||
The Hirschler Teich is a historic dam east of Clausthal-Zellerfeld . It was created in connection with the Upper Harz water shelf by Upper Harz miners in the 17th century and, especially during the 18th century, it was expanded and increased several times. It was the most important artificial pond for silver mining in Clausthal . Today it still has an important function as a drinking water pond for the town of Clausthal-Zellerfeld. Like all buildings in the Upper Harz Water Regale also Hirschler Pond since 2010 part of the UNESCO - World Heritage Mines of Rammelsberg, Historic Town of Goslar and Upper Harz Water .
location
The pond is about 2.5 kilometers east of Clausthal city center. It can only be reached on foot. The Hirschler pond is the uppermost pond in the so-called "peacock pond cascade". Below are the Obere Pfauenteich, the Middle Pfauenteich and the Lower Pfauenteich. Furthermore, further below is the Eulenspiegler pond and finally, approx. 10 kilometers further north-west, the Innerstetalsperre .
description
As with all Upper Harz ponds in the Clausthal-Zellerfeld area, the dam was built as an earth structure , i.e. with a bed of earth and rock. This embankment material was extracted locally and is predominantly stony. Compression work was not carried out, at least there are no accounting documents. This also explains why the dams are still several millimeters a year after more than 300 years ago today set . The seal was provided on the embankment on the water side and consists of turf . Its bottom outlet ( harrow ) was converted into a "new construction" in 1725/26 and has a harrow shaft. The pipe is still constructed as a historical log run . The bottom outlet has not been at the deepest point of the pond since 1725; a dead space of about 500 m³ remains . Up until the beginning of the 20th century there was a higher possibility of removal, the "upper case", which could feed about the top two meters of the storage space into the Caroline pit . The access to the gate valve in the form of a drywall vault with a door can still be seen on the airside embankment.
Building history
Many documents and records relating to the Hirschler Pond are preserved in the files of the Lower Saxony Mountain Archive. In some cases, there are even pay slips for the building tradesmen. Therefore, many measures of the past centuries can be traced.
The first construction of the Hirschler pond can be assumed around 1660. This was followed by several increases, first in 1711 by one laugher (1.92 m), then in 1738/39 by another laugher and finally in 1755 by ¼ laugher (0.48 m). For this last increase, 25,000 turf sods (around 350 m³) and 19,850 m³ of embankment material from locally abundant soil were used. In 1725/26, a leak made it necessary to renovate the sod seal by installing 242,000 sods (approx. 3000 m³) in front of the main lawn. On this occasion, the conversion to the new type with a harrow shaft in the middle of the dam for the bottom outlet construction took place.
The Huttaler watercourse to bring more water from the Söse catchment area to the south was excavated from 1763 to 1767 and in 1764 the head of the lawn at the two ends of the dam was raised and lengthened.
Storm damage to the dam body required repair work in 1765, and dams were settled by ¼ Lachter with "Röschenbergen". A wave protection wall was built. In 1766 it was found that the reservoir is losing water in the direction of the Amalia shaft ( position ) to the east . The pathway was sealed. In 1766 the curling races Oberer Fall was lowered. A year later it was decided to strengthen the dam on its entire length on the air side by ½ Lachter (0.96 m).
In 1832, a harrow leak required a total lowering for a detailed inspection and documentation of the harrow shaft. The first siphon line for the extraction of drinking water from the Clausthal-Zellerfeld public utility was installed in 1907. For a harrow repair, the pond had to be completely emptied again in 1961. In 1988 another total lowering was necessary. This resulted in the renewal of the sieve box at the inlet of the bottom outlet, repair of the wave protection wall, renovation of the harrow counterbalance and raising the base of the harrow house. The lining out of the harrow shaft and the condition of the run-out race were checked. A new harrow house was built in 1993. In the same year, the Upper Fall vaulted chamber at the airside dam foot, western end, was restored.
The pond was completely emptied again in 2010 for work on the bottom outlets. The top three meters of the harrow manhole was looted and replaced by a new solid oak wood. Corner strips were installed, the sieve box repaired. A further DN 300 extraction line was installed by means of horizontal pipe jacking, which primarily serves to extract raw water for the waterworks, but was also intended to function as a second bottom outlet. The siphon line from 1929 was taken out of service.
Catchment area and bypasses
The catchment area of the Hirschler pond consists almost exclusively of forest; Only in its periphery is it cut by the B 242 federal highway . The pond is very large in relation to its catchment area. Its degree of expansion is over 1.0; that is, with medium ratios, it will take more than a year to fill it. In order to increase the inflow, the Hirschler Graben (also known as the "Neue Graben") was created, which brought more water from the northeast, but this should only have been successful during the wet season. From the south-east, water could be fed in from the Huttaler Widerwaage over the Huttaler watercourse . There, water from the Huttaler and Schwarzenberger Graben collected, water from the Kautzthaler Graben, the Tränkegraben, but above all from the Polsterberger Liftkunst , could be brought in via the Schwarzenberg watercourse . Finally, the Upper Kehrzuggraben was also able to bring water from the southeast via the Benedikter Wasserlauf. The extremely high effort that was made to bring in more water underlines the great importance of the Hirschler pond for the Clausthal mining industry.
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Today there is only one connection to the Huttaler Widerwaage, which rarely feeds water into the Hirschler pond, especially since the Polsterberger lifting art is no longer practiced. The Hirschler pond receives its tributaries from its 0.81 km² small catchment area. Entering the catchment area as well as walking around the pond is not permitted due to the Water Protection Area Ordinance . Although the source of the Zellbach must be located in this area , you will look in vain for a pronounced tributary. In addition to the underground inflow, it consists of many tiny spring rivers.
Supplying the Caroline pit
The Caroline pit was on the one hand one of the most productive mines in Clausthal in the 18th century, on the other hand it was very high in the area, so that a supply of impact water was particularly difficult. The sweeping wheel , which had to stand close to the pit, could only be supplied via the "Upper Fall"; a removal provided at the western end of the embankment, with which approximately the top two meters of the storage space could be removed and fed to the Caroline pit. When the top two meters of the storage space were used up, an otherwise flooded ditch emerged from the storage space (Caroliner Kunstgraben, created in 1749), which at least contained the water from the Huttal watercourse and some tiny spring streams from the Upper Fall and thus the pit Caroline could feed.
Hunger stones
The Hirschler pond is the only one of the Upper Harz ponds with hunger stones on the bottom . The oldest is from 1767 and bears the inscription “Lack of water” next to the date. Then 10 to 12 more hunger stones were placed on the dry pond floor in the area of the sieve box, most of which mention a harrow repair and bear the names of the persons responsible. They are only visible when the pond is empty.
miscellaneous
In the 1950s and 1960s there was a pumping station on the west bank, with which up to 375 l / s of water could be pumped from the Hirschler pond over the Benedikter watercourse (contrary to its original flow direction) towards the Oberer Nassenwieser pond. It will only have been in operation very rarely, especially since the Obere Nassenwieser pond fills up as quickly as the Hirschler pond. Today you can still see traces of this system at the eastern mouth of the Benedictine watercourse.
On the pond floor, especially on the west bank, there is a rare beach vegetation that is dependent on changing water levels. In the pond there is an equally rare noble crayfish population .
The reservoir and catchment area are particularly protected today as drinking water protection areas and may not be entered. Bathing and fishing is prohibited. If the water level of the pond has fallen too far due to the drinking water withdrawal, additional water can be pumped over from the Fortuner pond further northeast via a pump and pipeline .
The Huttaler watercourse still has an important function to relieve floods today. Since its gradient runs in the direction of the Huttal, high water can be diverted from the pond in the direction of the Huttaler Widerwaage, where it then flows towards the Sösetalsperre . This relieves the peacock ponds below and the urban area of Clausthal.
photos
Hirschler pond, flood relief system and bypass Hirschler Graben
Hirschler pond dam and water surface, view from the southwest (2009)
literature
- Martin Schmidt : The water management of the Upper Harz mining industry . In: Series of publications by the Frontinus Society. V . 3rd, supplemented edition. Issue 13. Harzwasserwerke, Hildesheim 2002, ISBN 3-00-009609-4 .
- Walter Knissel , Gerhard Fleisch: cultural monument "Upper Harz water shelf" . An epoch-making achievement. 2nd Edition. Paper plane, Clausthal-Zellerfeld 2005, ISBN 3-89720-725-7 .
- Martin Schmidt: WasserWanderWege, a guide through the Upper Harz water shelf - world cultural heritage . Ed .: Harzwasserwerke GmbH. 4th edition. Papierflieger Verlag, Clausthal-Zellerfeld 2012, ISBN 978-3-86948-200-2 .
Web links
Individual evidence
- ↑ a b c d e f g h Martin Schmidt : The water management of the Upper Harz mining industry . In: Series of publications by the Frontinus Society. V . 3rd, supplemented edition. Issue 13. Harzwasserwerke, Hildesheim 2002, ISBN 3-00-009609-4 .
- ↑ Justus Teicke: Oberharzer Wasserregal cultural monument - historical hydraulic engineering systems with adapted maintenance in: H.-E. Minor: Modern methods and concepts in hydraulic engineering, ETH Zurich , Zurich, 2002
- ↑ Files of the Clausthal Upper Mining Authority , Lower Saxony Mountain Archive
- ↑ a b Justus Teicke: A new hunger stone for the Hirschler pond . In: General Harz-Berg-Kalender for 2012, Papierflieger Verlag GmbH, Clausthal-Zellerfeld, 2011, ISBN 978-3-86948-165-4
- ↑ Alfred Dumreicher: Entire overview of the water management of the north-western Upper Harz . 1st edition. Oberharzer Geschichts- und Museumsverein eV, Clausthal-Zellerfeld 2000, ISBN 3-9806619-2-X (new edition of the original from 1868).
- ↑ Martin Schmidt: WasserWanderWege, a guide through the Upper Harz water shelf - world cultural heritage . Ed .: Harzwasserwerke GmbH. 4th edition. Papierflieger Verlag, Clausthal-Zellerfeld 2012, ISBN 978-3-86948-200-2
- ^ Hugo Hase : Engineered structures of old water management in the Upper Harz (5th edition, Clausthal-Zellerfeld 1985), page 14