The Upper Harz Water Tunnels (german: Oberharzer Wasserläufe, ) are part of the

Upper Harz Water Regale The Upper Harz Water Regale (german: Oberharzer Wasserregal, ) is a system of dams, reservoirs, ditches and other structures, much of which was built from the 16th to 19th centuries to divert and store the water that drove the water wheels of the ...

- a network of

reservoirs A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including control ...

ditches A ditch is a small to moderate divot created to channel water. A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for plant irrigation. Ditches ar ...

, tunnels and other structures in the

Harz mountains The Harz () is a highland area in northern Germany. It has the highest elevations for that region, and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt, and Thuringia. The name ''Harz'' derives from the Middle High German ...

of central Germany. The German term ''Wasserlauf'' refers to the underground element (i.e. the tunnels) of the network of watercourses used in the historic

silver mining Silver mining is the extraction of silver from minerals, starting with mining. Because silver is often found in intimate combination with other metals, its extraction requires elaborate technologies. In 2008, ca.25,900 metric tons were consumed ...

industry of the Upper Harz. This network of ditches and tunnels was used to supply the mines with

headrace A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...

waters for their

water wheels A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...

from the 16th century onwards. In the system of the Upper Harz Water Regale there are over 35 such tunnels with a total length of about .

Construction

Although explosives were already in use in the 17th century in the mines of the Upper Harz, tunnels continued to be hewn out by hand, that is with hammer and chisel for much longer. The reason was that there were difficulties in determining the right amount of

gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). ...

and fears that tunnels running just under the surface would collapse or that the explosive would produce fissures in the rock causing water to leak away. Almost all water tunnels were driven by counter-heading. Until the 18th century the miners excavated tunnels by following the weakest rock; this sometimes created a zigzag route that deviated significantly from the direct line. Not until the 19th century were tunnels driven in a strictly direct line using explosives. The incline necessary to create a flow of water often amounted to less than 1% (in other words less than drop for every of length). The profile of the older tunnels, that had been driven with hammer and chisel, was sometimes as small as high and wide. The newer tunnels, however, were generally high and wide. Compared with ditches, tunnels had the important advantage that the water flowing through them underground could not freeze up. The tunnels were laid primarily to short cut the long ditch runs around mountains. Such cuts also produced a steeper incline (shorter distances descending the same height difference have a steeper slope). This raised the flow velocity and hence the hydraulic capacity of the watercourse. The disadvantage of tunnels was the high investment cost of building them.

List of working Upper Harz water tunnels

The working tunnels shown in this table follow the order in the latest listing by

Preussag TUI Group is a German leisure, travel and tourism company. TUI is an acronym for ''Touristik Union International'' ("Tourism Union International"). TUI AG was known as Preussag AG until 1997 when the company changed its activities from mining to ...

, which is based on their use in the various power stations.

List of disused Upper Harz water tunnels

"Disused" refers to all those tunnels that are no longer in service. Some of these are completely preserved; others, however, have largely fallen into ruin. The following list makes no claim to being complete.

Sources

* * * {{citation, surname1=Schmidt, Martin, title=Das Kulturdenkmal Oberharzer Wasserregal , publisher=Harzwasserwerke , publication-place=Clausthal-Zellerfeld, date=2005 , language=German , url=http://www.harzwasserwerke.de/downloads/br_ohwr.pdf

External links

Information by the ''Harzwasserwerke''
Tunnels in Germany Kunstgraben

Construction

List of working Upper Harz water tunnels

List of disused Upper Harz water tunnels

See also

Sources

External links