The Upper Harz Water Regale (, ) 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 mines in the Upper Harz region of Germany. The term regale, here, refers to the granting of royal privileges or rightsLangenscheidt's Muret-Sanders German-English dictionary (Berlin, 2004) gives one translation of the German word Regal as "regale", a legal and historical term. (droit de régale) in this case to permit the use of water for mining operations in the Harz mountains of Germany.
The Upper Harz Water Regale is one of the largest and most important historic mining water management systems in the world. The facilities developed for the generation of water power have been placed under protection since 1978 as cultural monuments. The majority are still used, albeit nowadays their purpose is primarily to support rural conservation (the preservation of a historic cultural landscape), nature conservation, tourism and swimming. From a water management perspective, several of the reservoirs still play a role in flood protection and the supply of drinking water. On 31 July 2010 the Regale was declared a UNESCO World Heritage Site affiliated with the Mines of Rammelsberg and the Historic Town of Goslar because of its importance in the development of mining techniques and testimony to the medieval history of ore mining.Oberharzer Wasserregal zum Weltkulturerbe ernannt tagesschau.de, accessed on 1 August 2010
The water system covers an area of roughly within the Lower Saxon part of the Harz, the majority of structures being found in the vicinity of Clausthal-Zellerfeld, Hahnenklee, Sankt Andreasberg, Buntenbock, Wildemann, Lautenthal, Schulenberg, Altenau and Torfhaus.
The Water Regale
Regale in this context means a royal prerogative. Through the so-called Bergregal, or "mining rights", the monarch granted the right to mine and, through the Wasserregal, he granted the right to use local water supplies for the purpose of mining. Other water users, particularly mill owners, had a lower priority. This 'water regale' or 'right to use water' was part of the overall Bergfreiheit or mining rights that were valid in Lower Saxony until the 1960s.
In German, the term Oberharzer Wasserwirtschaft ("Upper Harz Water Management") has also been frequently used to refer to these historic facilities. But this is not precise enough, because in the last hundred years an intensive, modern water management system has been put in place in the Upper Harz in the form of a number of new dams and their associated structures and ditches.
The Upper Harz mining industry
The Upper Harz was once one of the most important mining regions in Germany. The major products of its mines were silver, copper, lead, iron and, from the 19th century, zinc as well. The main source of income, however, was silver. From the 16th to the middle of the 19th centuries about 40–50% of the entire German silver production originated in the Upper Harz. The taxes raised from this contributed significantly to the revenue of the royal houses in Hanover and Brunswick-Wolfenbüttel and helped to secure their positions of power and influence within the Holy Roman Empire.
Its lucrativeness justified a high commitment in terms of investment and effort. Hereby the Upper Harz mining industry produced a considerable number of innovations and inventions, including such important advances as the man engine, the water-column engine (Wassersäulenmaschine) and the wire cable.
Mining and water
Mining becomes a very energy-intensive activity as soon as excavation extends any significant distance underground. In the Upper Harz, vein mining (Gangerzbergbau) was the main form of extraction, with excavation following the near-vertical lodes straight down into the earth. Only a few metres down the ingress of water increased the difficulty of excavation considerably. Initially it was mopped up using men standing on ladders, the so-called Wasserknechten ("water servants"), with their leather buckets. Later, the introduction of horses and whims (Göpel) enabled larger quantities of water to be lifted. But horses were expensive and had to be changed every few hours. As a result, mines – particularly the richer, deeper ones – started to use hydropower systems, able to work continuously, 24 hours a day. To do this, streams were diverted onto water wheels that drove reciprocating pumps in order to raise water from greater depths and in greater quantities. The principle was to raise water with water.
To operate these water wheels, a continuous and substantial supply of water was needed. Although the Upper Harz, with an annual precipitation of over 1300 millimetres per year, received copious amounts of water, the mines often lay high up in the mountains close to the watersheds where there were only a few streams of any size. In addition the flow of mountain streams in the rocky terrain was very variable. It often only needed a few weeks of low rainfall for the water supply to the mines to be threatened. This led to several mines having to be closed.
In their heyday, the mines of the Upper Harz were among the deepest in the world. For example, as early as 1700, shaft depths of 300 metres were exceeded and, around 1830, a depth of 600 metres was attained; this was now so deep that the mine was actually below sea level – something which was considered significant at that time. Deep shafts, however, demanded correspondingly high levels of energy to lift ore and pit water. This high energy consumption, combined with the heavy demand for water, led to even more strenuous attempts to develop the available water power.
The miners usually built new water structures in those periods when no ore could be extracted due to the lack of water to power the wheels. When the water wheels stopped running, the underground water that ingressed the mine could no longer be removed; the mine drowned and the miners were driven out. During these phases work concentrated on upgrading the facilities of the Upper Harz Water Regale.
Water diversion and storage elements
In all, 143 dammed ponds, 500 kilometres of ditch and 30 kilometres of tunnel were built for the collection, diversion and storage of the surface runoff water in the Upper Harz. In addition about 100 kilometres of drainage adits are included as part of the Regale. These facilities were not, however, all in operation at the same time. The Harzwasserwerke today operates and maintains 65 dammed ponds, 70 kilometres of ditch and 20 kilometres of tunnel. Several smaller dammed ponds still belong to the Lower Saxon State Forestry Department or are even in private hands.
The principle of water diversion is to collect the water in ditches, running almost parallel to the contours of the slope, and to divert it to the mining areas. These supply channels can easily be ten or more kilometres long (like the Dam Ditch or the Upper Schalke Ditch). Sometimes the water so collected was not fed directly to the water wheels, but into large, artificial, dammed ponds (Teiche) which acted as reservoirs, in order to ensure enough water was available for the wheels even in times of drought. From the bottom outlets of these ponds the water could be led into a ditch system in order to power the water wheels. Usually several wheels were arranged one after another, like a cascade, so that the water could be used to drive more than one wheel. In order to lead the water over as many wheels as possible, it had to be collected, stored and routed around at the highest possible elevation.
The technology of the time did not enable dams to be built with heights of more than about 15 metres. This meant that many small ponds had to be laid out rather than a few larger ones. By arranging the ponds in a cascade, water could be retained at a high elevation in order to drive as many water wheels as possible. A number of these pond cascades were built, comprising four to six ponds.
The majority of water wheels were used to drive pumps. Occasionally, the power they generated had to be transmitted over several hundred metres to the mine itself using flat rods (Feldgestänge). Important mines also had a reciprocal water wheel which was used to provide power for transporting the ore and the material to be crushed. All water wheels were of the overshot type. Apart from a few reconstructions, the water wheels all disappeared during the last century.
Structures Reservoirs
The 143 reservoirs or storage ponds, known as Teiche (singular: Teich), were impounded using earth-fill dams. Dam heights varied between 4.0 and 15.0 metres; impoundment volumes were, on average, about 150,000 cubic metres.
Ditches
The ditches are supply channels almost parallel to the terrain contours, with a very slight incline of around 1–2 per mille and are accompanied by an inspection path.
Tunnels
The underground water tunnels of between 20 and 1000 metres long were the most expensive investments in the Upper Harz Water Regale. They were worth the cost however because of their low operating costs and high hydraulic capacity.
Special structures The Sperberhai Dyke is an aqueduct built from 1732 to 1734 with a length of over 900 metres and a height of 16 metres. The Oderteich differs considerably from the other Upper Harz ponds with regard to its construction materials and dimensions. Following its completion in 1722 to the start of the modern dam building period in 1892, it was the largest dam in Germany. In the Polsterberg Pumphouse water could be pumped from the Dam Ditch to a height of 8 metres using hydropower. The Huttaler Widerwaage is also frequently mentioned in this connexion: it is quite complex and enables water to flow in two different directions.
Tourism Due to the sheer number of structures and the length of the ditches the Upper Harz Water Regale is best explored on foot. Thanks to the Harzwasserwerke a large number of waterside footpaths have been created in recent years: the so-called Wasserwanderwege. Visitors can get to know about the typical elements that make up the Upper Harz Water Regale by means of information boards along the clearly marked routes. With a few exceptions, most of the ponds can be used by swimmers during the summer months. The majority are also leased to local angling clubs.
History
Construction Mining activity in the Harz goes back to the 10th and 11th centuries. The first water wheels in the Harz were erected in the 13th century in the Pandelbach valley southeast of Seesen. At that time mining, including this early use of the so-called waterworks (Wasserkünste) for the mines, was managed by the Cistercian abbey at Walkenried.
The Black Death in the Middle Ages depopulated the Harz to a great extent and almost brought mining operations to a standstill. Another factor was probably that mining had reached its technical limits at the time with depths of up to about 60 metres.
A clear recovery followed from about 1520 onwards, initially at the instigation of the Duke of Brunswick-Wolfenbüttel, Henry the Younger. But it was his son, Julius, Duke of Brunswick-Lüneburg, who gave added impetus to existing mining operations in the Upper Harz and initiated the creation of a large number of ponds and ditches.
It was the extensive use of hydropower that made the mining boom in the Upper Harz possible. As the mines became ever deeper over time they needed more and more energy. The lack of water following months of little rain or long periods of frost was time and again a limiting factor for the mines. The expansion of the water system was achieved by raising the existing pond dams, building new dams, laying new ditches and extending existing ditch runs.
Further improvements: water tunnels and drainage adits