The Dyke Ditch (german: Dammgraben) is the longest artificial ditch in the

Upper Harz The Upper Harz (german: Oberharz, ) refers to the northwestern and higher part of the Harz mountain range in Germany. The exact boundaries of this geographical region may be defined differently depending on the context. In its traditional sense, th ...

in central Germany. Its purpose was to collect

surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...

for the operation of the

Upper Harz mining industry Mining in the Upper Harz region of central Germany was a major industry for several centuries, especially for the production of silver, lead, copper, and, latterly, zinc as well. Great wealth was accumulated from the mining of silver from the 16t ...

from precipitation-heavy regions a long way away (particularly from the

Bruchberg At , the Bruchberg in the Upper Harz is the second highest mountain in Lower Saxony and the third highest in the Harz mountains in North Germany. It lies between Altenau and Torfhaus in the middle of the Harz National Park. The Bruchberg is mo ...

and parts of the

Brocken The Brocken, also sometimes referred to as the Blocksberg, is the highest peak in the Harz mountain range and also the highest peak in Northern Germany; it is near Schierke in the German state of Saxony-Anhalt between the rivers Weser and Elbe. ...

massif). It was laid in 1732 and continually extended eastwards until 1827. Its original length was about 25 km; this was successively shortened by

water tunnels Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a s ...

between 1820 and 1861 to around 19 km. It is a central component of the Upper Harz Water Regale. Its takes its name from the Sperberhai Dyke which is, in fact, an embankment on top of which the Dyke Ditch runs in an aqueduct in order to cross a depression.

History

The history of the Dyke Ditch was initially closely related to the history of the Sperberhai Dyke. Not until the completion of the dyke in 1734 could large watercourses east of Clausthal be tapped into: the streams of the Großer and Kleiner Gerlachsbach. In the years that followed, the Dyke Ditch was continually extended eastwards. In 1736 it was extended as far as the Kleiner Oker. In 1742, a neighbouring ditch, the Morgenbrodtstal Ditch, was built to carry water from the Große and Kleine Söse rivers to the Dyke Ditch. In 1774, it was lengthened as far as the so-called ''Wiege'' ("scales") on the Dyke Ditch and in 1820, after the two Kellwasser tunnels had been driven and the Blochschleife Ditch laid, the Kellwasser and the Blochschleife were connected to the Dyke Ditch system. The last addition was made in 1827, when the Clausthal Flood Ditch, the Flörichshai Ditch and Abbe Ditch enabled water from east of the

and the western

to be made available for the Upper Harz mines. Yet another extension would have been possible but was no longer discussed. Now, attempts were made to fundamentally solve the energy problem in the Upper Harz mines by building deeper drainage adits (such as the Ernst August Adit). In addition from the second half of the 19th century other forms of energy (steam engines) were brought into operation, initially alongside water power. In the middle of the 19th century work was carried out to optimise water flow in area of the 10 km long section between Sperberhai Dyke and Clausthal. By cutting tunnels, several ditch detours around mountains were able to be shortened considerably. In addition to clear advantages in the maintenance overhead and winter operations, the increase in incline (the same drop being covered in a shorter distance) played an important role in increasing the hydraulic capacity. The water tunnels, built around 1850, were the Rothenberg, Coventhai, Dietrichsberg and Bielenwiese Tunnels. During its middle years the Dyke Ditch could carry up to 13 million cubic metres of water per year over the Sperberhai Dyke to the Clausthal Plateau. That made it one of the most important lifelines in the Upper Harz mining region. Following the closure of the mines the Dyke Ditch supplied water up to about 1978 for the generation of electricity in Kaiser Wilhelm Shaft. Since 1978 the water of the Dyke Ditch has been led to the Mönch valley of the

Oker Reservoir The Oker is a river in Lower Saxony, Germany, that has historically formed an important political boundary. It is a left tributary of the River Aller, in length and runs in a generally northerly direction. Origin and meaning of the name The r ...

at the end of the Dyke Ditch, where it still drives turbines for the generation of electricity and is then made available for the drinking water supplies of the

Harzwasserwerke The Harzwasserwerke GmbH (; English: Harz Water Works Limited) is a major German water company and dam operator based in Hildesheim, located within the German federal state of Lower Saxony. Founded in 1928, the Harzwasserwerke were tasked with sup ...

. Until about 2000, the Dyke Ditch also provided drinking water to the mining town of

Altenau Altenau () is a town and a former municipality in the district of Goslar, in Lower Saxony, Germany. Since 1 January 2015 it is part of the town Clausthal-Zellerfeld. It is situated in the middle of the Harz mountains, between Clausthal-Zellerf ...

. This has since been withdrawn because the natural water supply was very unreliable, especially in winter and the quality of the water could also change very quickly. The operator of the Dyke Ditch today is the ''

''.

Catchment area

The Dyke Ditch draws its water from the region of six Harz rivers: * Söse over the Morgenbrodstal Ditch (1715–1718; length 3,970 m) * Sieber over the Clausthal Flood Ditch (also called the Rotenbeeke Ditch) (1797; length 3,900 m) *

Oder The Oder ( , ; Czech, Lower Sorbian and ; ) is a river in Central Europe. It is Poland's second-longest river in total length and third-longest within its borders after the Vistula and Warta. The Oder rises in the Czech Republic and flows thr ...

over the Clausthal Flood Ditch and the Flörichshai Ditch (1826; length 1,050 m) *

Ecker The Ecker is a , right-hand, southeast tributary of the Oker which runs mainly through the Harz mountains in the German states of Saxony-Anhalt and Lower Saxony. Course From its source to Abbenrode the Ecker is a border river, today running b ...

over the Abbe Ditch (1827; length 1,540 m) * Radau over the Abbe Ditch * Oker over the Dam Ditch (1725–1840; length 14,690 m) The Dyke Ditch system crosses several

watershed Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, called a "watershe ...

s as a result.

Statistics

The Dyke Ditch today is 19 km long. 15.4 km of that are open ditches and 3.6 km are underground water tunnels. Depending on how they are counted, its associated ditch system has an overall length of 49 km. On most routes the water descends by around 60 m. Its

flow rate Flow rate may refer to: * Flow measurement, a quantification of bulk fluid movement * Mass flow rate, the mass of a substance which passes per unit of time * Volumetric flow rate, the volume of fluid which passes per unit time ** Discharge (hydrol ...

reaches a maximum of about 1 m³/s.

Footpath

A footpath from Osterode to Thale, the

Harzer Hexenstieg The Harz Witches' Trail (german: Harzer Hexenstieg) is a footpath, just under 100 km long, in Germany that runs from Osterode through the Harz mountains and over its highest peak, the Brocken, to Thale. It is a project by the Harz Transpo ...

("Harz Witches' Climb"), runs along the Dam Ditch.

Sources

* * {{Coord, 51, 48, 10, N, 10, 30, 12, E, type:waterbody_elevation:640_region:DE-NI, display=title Upper Harz Water Regale Clausthal-Zellerfeld Kunstgraben CDammgraben CDyke Ditch