82-519: The Oderteich is an historic reservoir about seven kilometres northeast of Sankt Andreasberg in the Upper Harz in central Germany . It was built by miners from St. Andreasberg in the years 1715 to 1722 and, today, is an important component of the water supply network known as the Upper Harz Water Regale ( Oberharzer Wasserregal ). Moreover, for 170 years, from the time it was completed to
164-537: A block for migrating fish, trapping them in one area, producing food and a habitat for various water-birds. They can also flood various ecosystems on land and may cause extinctions. Creating reservoirs can alter the natural biogeochemical cycle of mercury . After a reservoir's initial formation, there is a large increase in the production of toxic methylmercury (MeHg) via microbial methylation in flooded soils and peat. MeHg levels have also been found to increase in zooplankton and in fish. Dams can severely reduce
246-791: A chain up the valley. Coastal reservoirs are fresh water storage reservoirs located on the sea coast near a river mouth to store the flood water of a river. As the land-based reservoir construction is fraught with substantial land submergence, coastal reservoirs are preferred economically and technically since they do not use scarce land area. Many coastal reservoirs were constructed in Asia and Europe. Saemanguem in South Korea, Marina Barrage in Singapore, Qingcaosha in China, and Plover Cove in Hong Kong are
328-636: A conventional oil-fired thermal generation plant. For instance, In 1990, the impoundment behind the Balbina Dam in Brazil (inaugurated in 1987) had over 20 times the impact on global warming than would generating the same power from fossil fuels, due to the large area flooded per unit of electricity generated. Another study published in the Global Biogeochemical Cycles also found that newly flooded reservoirs released more carbon dioxide and methane than
410-475: A doubling of the reservoir capacity to 1.67 million cubic metres. The cost of construction rose considerably during the build phase, not just as a result of the increase in dam height, but also other factors: in the end the Oderteich dam cost around 11,700 Reichstalers, almost four times the originally estimated and approved cost. Because the structure was so convincing, however, subsequent requests and approvals for
492-529: A drop of water seep into the ocean without benefiting mankind." He created the reservoir named Parakrama Samudra ("sea of King Parakrama"). Vast artificial reservoirs were also built by various ancient kingdoms in Bengal, Assam, and Cambodia. Many dammed river reservoirs and most bank-side reservoirs are used to provide the raw water feed to a water treatment plant which delivers drinking water through water mains. The reservoir does not merely hold water until it
574-525: A few such coastal reservoirs. Where water is pumped or siphoned from a river of variable quality or size, bank-side reservoirs may be built to store the water. Such reservoirs are usually formed partly by excavation and partly by building a complete encircling bund or embankment , which may exceed 6 km (4 miles) in circumference. Both the floor of the reservoir and the bund must have an impermeable lining or core: initially these were often made of puddled clay , but this has generally been superseded by
656-455: A high-level reservoir is filled with water using high-performance electric pumps at times when electricity demand is low, and then uses this stored water to generate electricity by releasing the stored water into a low-level reservoir when electricity demand is high. Such systems are called pump-storage schemes. Reservoirs can be used in a number of ways to control how water flows through downstream waterways: Reservoirs can be used to balance
738-570: A loss in both quantity and quality of water necessary for maintaining ecological balance and pose a risk of increasing severity and duration of droughts due to climate change. In summary, they consider it a misadaptation to climate change. Proponents of reservoirs or substitution reserves, on the other hand, see them as a solution for sustainable agriculture while waiting for a truly durable agricultural model. Without such reserves, they fear that unsustainable imported irrigation will be inevitable. They believe that these reservoirs should be accompanied by
820-419: A narrow valley or canyon may cover relatively little vegetation, while one situated on a plain may flood a great deal of vegetation. The site may be cleared of vegetation first or simply flooded. Tropical flooding can produce far more greenhouse gases than in temperate regions. The following table indicates reservoir emissions in milligrams per square meter per day for different bodies of water. Depending upon
902-592: A reservoir is called the "conservation pool". In the United Kingdom, "top water level" describes the reservoir full state, while "fully drawn down" describes the minimum retained volume. There is a wide variety of software for modelling reservoirs, from the specialist Dam Safety Program Management Tools (DSPMT) to the relatively simple WAFLEX , to integrated models like the Water Evaluation And Planning system (WEAP) that place reservoir operations in
SECTION 10
#1732852481183984-720: A river valley, with the potential to wash away towns and villages and cause considerable loss of life, such as the devastation following the failure of containment at Llyn Eigiau which killed 17 people. (see also List of dam failures ) A notable case of reservoirs being used as an instrument of war involved the British Royal Air Force Dambusters raid on Germany in World War II (codenamed " Operation Chastise " ), in which three German reservoir dams were selected to be breached in order to damage German infrastructure and manufacturing and power capabilities deriving from
1066-513: A rod operated from the control hut or Striegelhaus positioned above the shaft. The oak chute is designed in such a way that, even when the valve is shut, it remains submerged in water and so does not rot. This explains why the oak chutes fitted in 1715 are still being used. The entire bottom outlet design is known in the Upper Harz as a Striegel . Every reservoir needs a spillway which ensures that even under conditions of exceptionally high water,
1148-455: A slope of 1:0.5. On the downstream side the dam measures about 19 m from its base. The dam wall has proved to be a very durable structure and, like the entire reservoir, is still virtually in its original condition. Fundamentally it is not quite clear whether the Oderteich dam structure is an earth-fill dam or a masonry dam . It is probably a combination of the two. The tendency for the Oderteich to use particularly long-lasting materials
1230-478: A solution. At that time there must have been 50 to 60 small reservoirs in operation. Their design, however, could not simply be copied, because there was nowhere in the vicinity of the Oderteich to cut grass sods like those used to seal the dams of the Upper Harz reservoirs. In the meantime, the Rehberg Ditch, which had initially only been made of wooden channels ( Holzgefludern ), was being 'walled'; in other words
1312-574: A territorial project that unites all water stakeholders with the goal of preserving and enhancing natural environments. Two main types of reservoirs can be distinguished based on their mode of supply. Circa 3000 BC, the craters of extinct volcanoes in Arabia were used as reservoirs by farmers for their irrigation water. Dry climate and water scarcity in India led to early development of stepwells and other water resource management techniques, including
1394-471: Is a natural lake whose level was raised by a low dam and into which the River Dee flows or discharges depending upon flow conditions, as part of the River Dee regulation system . This mode of operation is a form of hydraulic capacitance in the river system. Many reservoirs often allow some recreational uses, such as fishing and boating . Special rules may apply for the safety of the public and to protect
1476-480: Is a water reservoir for agricultural use. They are filled using pumped groundwater , pumped river water or water runoff and are typically used during the local dry season. This type of infrastructure has sparked an opposition movement in France, with numerous disputes and, for some projects, protests, especially in the former Poitou-Charentes region where violent demonstrations took place in 2022 and 2023. In Spain, there
1558-437: Is also used technically to refer to certain forms of liquid storage, such the "coolant reservoir" that captures overflow of coolant in an automobile's cooling system. Dammed reservoirs are artificial lakes created and controlled by a dam constructed across a valley and rely on the natural topography to provide most of the basin of the reservoir. These reservoirs can either be on-stream reservoirs , which are located on
1640-399: Is an enlarged lake behind a dam , usually built to store fresh water , often doubling for hydroelectric power generation . Reservoirs are created by controlling a watercourse that drains an existing body of water, interrupting a watercourse to form an embayment within it, excavating, or building any number of retaining walls or levees to enclose any area to store water. The term
1722-406: Is best demonstrated in the design of the bottom outlet. At the lowest point in the valley, a shaft was let into the dam, that had a cross-section of about 1.10 × 1.20 m. This shaft is edged with large, hewn granite blocks and descends to the natural floor of the valley. From the bottom of the shaft runs a tunnel, 0.75 metres wide and 0.90 metres high into the reservoir. This tunnel enables the water in
SECTION 20
#17328524811831804-501: Is greater acceptance because all beneficiary users are involved in the implementation of the system. The specific debate about substitution reservoirs is part of a broader discussion related to reservoirs used for agricultural irrigation, regardless of their type, and a certain model of intensive agriculture. Opponents view these reservoirs as a monopolization of resources benefiting only a few, representing an outdated model of productive agriculture. They argue that these reservoirs lead to
1886-466: Is needed: it can also be the first part of the water treatment process. The time the water is held before it is released is known as the retention time . This is a design feature that allows particles and silts to settle out, as well as time for natural biological treatment using algae , bacteria and zooplankton that naturally live in the water. However natural limnological processes in temperate climate lakes produce temperature stratification in
1968-528: Is now used by the Aquarius Golf Club. Service reservoirs perform several functions, including ensuring sufficient head of water in the water distribution system and providing water capacity to even-out peak demand from consumers, enabling the treatment plant to run at optimum efficiency. Large service reservoirs can also be managed to reduce the cost of pumping by refilling the reservoir at times of day when energy costs are low. An irrigation reservoir
2050-419: Is stored in the reservoir. Any excess water can be spilled via a specifically designed spillway. Stored water may be piped by gravity for use as drinking water , to generate hydro-electricity or to maintain river flows to support downstream uses. Occasionally reservoirs can be managed to retain water during high rainfall events to prevent or reduce downstream flooding. Some reservoirs support several uses, and
2132-466: Is the portion of the reservoir that can be used for flood control, power production, navigation , and downstream releases. In addition, a reservoir's "flood control capacity" is the amount of water it can regulate during flooding. The "surcharge capacity" is the capacity of the reservoir above the spillway crest that cannot be regulated. In the United States, the water below the normal maximum level of
2214-735: Is true is that from its completion in 1722 to the end of the 19th century, a period of 170 years, it had the largest dam in Germany. Not until the Eschbach Dam in the Bergisches Land was finished in 1891 with a height of 23 m was there a higher dam than the Oderteich. In the middle of the 1990s, the operators of the Oderteich, the Harzwasserwerke , laid out a waterside footpath (the WasserWanderWeg ) as an educational trail . This runs along
2296-448: The Ruhr and Eder rivers. The economic and social impact was derived from the enormous volumes of previously stored water that swept down the valleys, wreaking destruction. This raid later became the basis for several films. All reservoirs will have a monetary cost/benefit assessment made before construction to see if the project is worth proceeding with. However, such analysis can often omit
2378-646: The 1800s, most of which are lined with brick. A good example is the Honor Oak Reservoir in London, constructed between 1901 and 1909. When it was completed it was said to be the largest brick built underground reservoir in the world and it is still one of the largest in Europe. This reservoir now forms part of the southern extension of the Thames Water Ring Main . The top of the reservoir has been grassed over and
2460-475: The Clausthal Mining Office, in which he proposed the construction of the Oderteich dam, sealed with granitic sand, as well as two embankments made of granite blocks. This proposal was duly taken up, but Caspar Dannenberger, the father of the Oderteich dams, did not survive to see it completed. He died on 23 April 1713. Planning was carried out in 1714 and, on 14 September, King George Louis authorised
2542-710: The Meroitic town of Butana . The Hafirs catch the water during rainy seasons in order to ensure water is available for several months during dry seasons to supply drinking water, irrigate fields and water cattle. The Great Reservoir near the Lion Temple in Musawwarat es-Sufra is a notable hafir in Kush. In Sri Lanka , large reservoirs were created by ancient Sinhalese kings in order to store water for irrigation. The famous Sri Lankan king Parākramabāhu I of Sri Lanka said "Do not let
Oderteich - Misplaced Pages Continue
2624-406: The Oderteich overflows several times a year. There is no fishway at the Oderteich. The relatively acidic condition of the water is probably not a good habitat for fish. Most of the water comes from areas of raised bog and is rich in humic acid . Humic acid also causes its brown coloration. In addition, it reduces surface tension , something which causes conspicuous white horses such as occur in
2706-485: The US. The capacity, volume, or storage of a reservoir is usually divided into distinguishable areas. Dead or inactive storage refers to water in a reservoir that cannot be drained by gravity through a dam's outlet works , spillway, or power plant intake and can only be pumped out. Dead storage allows sediments to settle, which improves water quality and also creates an area for fish during low levels. Active or live storage
2788-399: The additional extra funding were not a problem. The three chief miners ( Bergmeister ) and excavation engineers ( Grabensteiger ) were rewarded in 1724 with bonuses ranging from 12 to 100 Talers . The Sankt Andreasberg mine ground to a standstill in 1913. From then on the water of the Oderteich was used to generate electricity instead. It was now routed to Sankt Andreasberg itself, where it
2870-584: The amount of water reaching countries downstream of them, causing water stress between the countries, e.g. the Sudan and Egypt , which damages farming businesses in the downstream countries, and reduces drinking water. Bergmeister A Bergmeister ( Latin : Magister montium ) was a mine manager or foreman in German-speaking Europe who, along with the Bergvogt , was one of the officials serving on
2952-523: The area flooded versus power produced, a reservoir built for hydro- electricity generation can either reduce or increase the net production of greenhouse gases when compared to other sources of power. A study for the National Institute for Research in the Amazon found that hydroelectric reservoirs release a large pulse of carbon dioxide from decay of trees left standing in the reservoirs, especially during
3034-428: The base of the dam or some distance away. In a flat river valley a reservoir needs to be deep enough to create a head of water at the turbines; and if there are periods of drought the reservoir needs to hold enough water to average out the river's flow throughout the year(s). Run-of-the-river hydro in a steep valley with constant flow needs no reservoir. Some reservoirs generating hydroelectricity use pumped recharge:
3116-547: The building of a reservoir at Girnar in 3000 BC. Artificial lakes dating to the 5th century BC have been found in ancient Greece. The artificial Bhojsagar lake in present-day Madhya Pradesh state of India, constructed in the 11th century, covered 650 square kilometres (250 sq mi). The Kingdom of Kush invented the Hafir , a type of reservoir, during the Meroitic period . 800 ancient and modern hafirs have been registered in
3198-490: The centre of the Harz National Park . Swimming is allowed in the southern third of the reservoir and in the vicinity of the dam. The northern area is barred to swimmers in the summer by a chain and is meant to be exclusively reserved as a biotope . There is a roughly 4.5 km long circular walk around the reservoir, for which good walking boots are recommended. This path is routed along board walks in places because of
3280-556: The channel. The old outlet is clearly identifiable by a weir, which was built in 1895 by the Royal Central Smithy in Clausthal Königlichen Centralschmiede Clausthal . This weir enables the maximum storage level to be raised by a metre or so. Originally the spillway ran for almost a 100 metres in a straight line southwards before the water dropped into the valley. This course is still visible in
3362-417: The construction of the Oderteich dam in a most gracious special decree and made the available the sum estimated for the project: a total of 3048 thalers and 27 gl. The construction phase actually started in early 1715. Initially a core trench was excavated into which the dam was embedded. The building material for this was excavated from the land earmarked for the future reservoir. Granite blocks needed for
Oderteich - Misplaced Pages Continue
3444-442: The context of system-wide demands and supplies. In many countries large reservoirs are closely regulated to try to prevent or minimize failures of containment. While much of the effort is directed at the dam and its associated structures as the weakest part of the overall structure, the aim of such controls is to prevent an uncontrolled release of water from the reservoir. Reservoir failures can generate huge increases in flow down
3526-487: The dam crest to the two spillways, past the two additional basins and via the overspill marker then downhill alongside the Großer Ausflut and its chute to the downstream foot of the dam, from where there is an impressive view of the stonework on this side of the dam and where the bottom outlet and start of the Rehberg Ditch can be seen. Information boards along the path explain the various structures. The Oderteich lies in
3608-548: The dam located at the narrowest practical point to provide strength and the lowest cost of construction. In many reservoir construction projects, people have to be moved and re-housed, historical artifacts moved or rare environments relocated. Examples include the temples of Abu Simbel (which were moved before the construction of the Aswan Dam to create Lake Nasser from the Nile in Egypt ),
3690-419: The dam since that time. In 1886/87, however it appears that the conclusion was reached that the capacity of the spillway needed to be increased. To achieve this another spillway was built a few metres east of the existing one. It had an inlet breadth of 12 metres and its crest was about a metre higher than that of the old, main spillway. This outlet crosses under the B 242 parallel to the main one and merges with
3772-431: The dam was being built. This spillway had to be laid higher and higher as the dam grew in size. Shortly after work on the dam had started there were discussions about raising it even higher than originally planned. In 1717 it was agreed to increase its height from the initial seven Lachter to nine Lachter (roughly equating to just under 18 metres). This resulted in an increase in the dam volume of around 55 percent and
3854-460: The developed world Naturally occurring lakes receive organic sediments which decay in an anaerobic environment releasing methane and carbon dioxide . The methane released is approximately 8 times more potent as a greenhouse gas than carbon dioxide. As a human-made reservoir fills, existing plants are submerged and during the years it takes for this matter to decay, will give off considerably more greenhouse gases than lakes do. A reservoir in
3936-507: The downstream river to maintain river quality, support fisheries, to maintain downstream industrial and recreational uses or for a range of other purposes. Such releases are known as compensation water . The units used for measuring reservoir areas and volumes vary from country to country. In most of the world, reservoir areas are expressed in square kilometers; in the United States, acres are commonly used. For volume, either cubic meters or cubic kilometers are widely used, with acre-feet used in
4018-640: The end of the 19th century, the Oderteich had the largest dam in Germany . The dam lies at a height of 725 m above NN by the B ;242 federal highway, about a kilometre west of its intersection with the B 4 . The Oderteich was built in order to be able to deliver a reliable supply of water to the water wheels of the St. Andreasberg mine via the Rehberg Ditch, even during times of drought. Its capacity of 1.7 million cubic metres was, far and away,
4100-440: The environmental impacts of dams and the reservoirs that they contain. Some impacts, such as the greenhouse gas production associated with concrete manufacture, are relatively easy to estimate. Other impacts on the natural environment and social and cultural effects can be more difficult to assess and to weigh in the balance but identification and quantification of these issues is now commonly required in major construction projects in
4182-491: The first decade after flooding. This elevates the global warming impact of the dams to levels much higher than would occur by generating the same power from fossil fuels . According to the World Commission on Dams report (Dams And Development), when the reservoir is relatively large and no prior clearing of forest in the flooded area was undertaken, greenhouse gas emissions from the reservoir could be higher than those of
SECTION 50
#17328524811834264-413: The flow in highly managed systems, taking in water during high flows and releasing it again during low flows. In order for this to work without pumping requires careful control of water levels using spillways . When a major storm approaches, the dam operators calculate the volume of water that the storm will add to the reservoir. If forecast storm water will overfill the reservoir, water is slowly let out of
4346-580: The hydroelectric reservoirs there do emit greenhouse gases, it is on a much smaller scale than thermal power plants of similar capacity. Hydropower typically emits 35 to 70 times less greenhouse gases per TWh of electricity than thermal power plants. A decrease in air pollution occurs when a dam is used in place of thermal power generation, since electricity produced from hydroelectric generation does not give rise to any flue gas emissions from fossil fuel combustion (including sulfur dioxide , nitric oxide and carbon monoxide from coal ). Dams can produce
4428-432: The landscape is relatively flat. Other service reservoirs can be storage pools, water tanks or sometimes entirely underground cisterns , especially in more hilly or mountainous country. Modern reserviors will often use geomembrane liners on their base to limit seepage and/or as floating covers to limit evaporation, particularly in arid climates. In the United Kingdom, Thames Water has many underground reservoirs built in
4510-520: The largest of all the Upper Harz reservoirs at that time and was enough to cope with periods of low precipitation of up to three months. Today the water of the Oderteich still drives several hydropower stations within its own valley, at the Samson Pit and in the Sperrlutter valley. The dam also serves to prevent the regular flooding that happened each year in spring before the dam was built. In 1703
4592-461: The main spillway shortly before the high-water marker and its adjoining chute ( Schussrinne ). This additional spillway enables the discharge capacity during times of flood to be increased by about 50%. When the Oderteich is fully emptied the remains of coffer dam can be seen about 200 metres above the main dam. This was built in 1898 when the Oderteich Reservoir was empty in order to reduce
4674-470: The modern use of rolled clay. The water stored in such reservoirs may stay there for several months, during which time normal biological processes may substantially reduce many contaminants and reduce turbidity . The use of bank-side reservoirs also allows water abstraction to be stopped for some time, for instance when the river is unacceptably polluted or when flow conditions are very low due to drought . The London water supply system exhibits one example of
4756-489: The new Rehberg Ditch was completed, diverting water from the river Oder and bringing it to St. Andreasberg. This was initially a great improvement in the supply of water power for the mines there, but the Oder could still not deliver enough water during a period of extended drought. So the call for a water reservoir quickly became shrill. A glance at the Upper Harz 'ponds' ( Teiche ) near Clausthal-Zellerfeld and Hahnenklee suggested
4838-593: The new top water level exceeds the watershed height on one or more of the feeder streams such as at Llyn Clywedog in Mid Wales . In such cases additional side dams are required to contain the reservoir. Where the topography is poorly suited to forming a single large reservoir, a number of smaller reservoirs may be constructed in a chain, as in the River Taff valley where the Llwyn-on , Cantref and Beacons Reservoirs form
4920-415: The operating rules may be complex. Most modern reservoirs have a specially designed draw-off tower that can discharge water from the reservoir at different levels, both to access water as the water level falls, and to allow water of a specific quality to be discharged into the downstream river as "compensation water": the operators of many upland or in-river reservoirs have obligations to release water into
5002-428: The original streambed of the downstream river and are filled by creeks , rivers or rainwater that runs off the surrounding forested catchments, or off-stream reservoirs , which receive diverted water from a nearby stream or aqueduct or pipeline water from other on-stream reservoirs. Dams are typically located at a narrow part of a downstream of a natural basin. The valley sides act as natural walls, with
SECTION 60
#17328524811835084-477: The pre-flooded landscape, noting that forest lands, wetlands, and preexisting water features all released differing amounts of carbon dioxide and methane both pre- and post-flooding. The Tucuruí Dam in Brazil (completed in 1984) had only 0.4 times the impact on global warming than would generating the same power from fossil fuels. A two-year study of carbon dioxide and methane releases in Canada concluded that while
5166-437: The quality of the water and the ecology of the surrounding area. Many reservoirs now support and encourage less formal and less structured recreation such as natural history , bird watching , landscape painting , walking and hiking , and often provide information boards and interpretation material to encourage responsible use. Water falling as rain upstream of the reservoir, together with any groundwater emerging as springs,
5248-464: The relocation of the village of Capel Celyn during the construction of Llyn Celyn , and the relocation of Borgo San Pietro of Petrella Salto during the construction of Lake Salto . Construction of a dammed reservoir will usually require the river to be diverted during part of the build, often through a temporary tunnel or by-pass channel. In hilly regions, reservoirs are often constructed by enlarging existing lakes. Sometimes in such reservoirs,
5330-420: The reservoir can become empty. This happens about every five to ten years, the last occasions being in 1991, 1999 and 2003. The surcharge capacity of the Oderteich is very small. Its reservoir can only store 14% of its annual discharge. This results in unusually high fluctuations in the water level of the reservoir, which can even change from being largely empty to overflowing within a few hours. This explains why
5412-627: The reservoir prior to, and during, the storm. If done with sufficient lead time, the major storm will not fill the reservoir and areas downstream will not experience damaging flows. Accurate weather forecasts are essential so that dam operators can correctly plan drawdowns prior to a high rainfall event. Dam operators blamed a faulty weather forecast on the 2010–2011 Queensland floods . Examples of highly managed reservoirs are Burrendong Dam in Australia and Bala Lake ( Llyn Tegid ) in North Wales . Bala Lake
5494-433: The reservoir to equalise with the water level in the shaft. From the bottom of the shaft, two wooden chutes ( Holzgerenne ) lead to the downstream side of the dam base. These chutes, made of oak, have a right-angled cross-section of about 25 × 25 cm and feature a valve on the bottom of the shaft that operates in a similar way to the type of bathplug that is closed from below. This valve can be pushed up or pulled shut using
5576-458: The rock is very impressive especially on the spillway. To begin with the spillway was not large enough: in December 1760 water overspilled the dam during a period of exceptional high water. Damage was limited, which said something, especially about the stable design of the dam. In response to this incident the dam was raised by about a metre, which has probably merely compensated for the subsidence of
5658-477: The seal of granitgrus and it was confirmed that this could not easily be worked with clay picks. These plans were later shelved for reasons that are not clear, although it is likely that the project was not seen as economical. The dam on the Oderteich differs considerably from the other dams in the Upper Harz Water Regale. The structure is clearly higher and the reservoir capacity just under three times
5740-423: The terrain to the experienced eye. But when towards the end of the construction phase in there were still not enough stones to complete the dam wall, a steep, 80-metre-long Große Ausflut ("large spillway") was blasted out of the rock roughly 60 metres below the weir at right angles to the original spillway. Perhaps it was hoped that this would increase the hydraulic capacity of the outlet. The channel carved out of
5822-410: The terrain which resembles that of a raised bog . Winter sports, such as skating, on the reservoir in winter are not recommended, because the large variations in the water level make the formation of a stable ice surface difficult, especially near the shores. Until the 1960s there was a dam keeper's house at the western end of the dam, which was used latterly as a restaurant. It was demolished when it
5904-452: The turbulence at the intakes and outlets of the reservoir. The Oderteich is frequently reported as the "oldest dam and reservoir in Germany". This accolade is disputed, however, because in the early 18th century in the area of Clausthal-Zellerfeld, Buntenbock and Hahnenklee there was already a large number of 'reservoirs' ( Talsperren ) as defined by the German industrial norm , DIN 19700-11. What
5986-431: The up- and downstream sides of the dam were cut from small quarries; this also provided a supply of granitic sand. The mining of material for the dam enabled the future reservoir capacity to be further enlarged. The work took until 1722. Because excess water could neither be drained through the relatively small bottom outlet during the construction period nor be impounded, a spillway had to be continuously available whilst
6068-493: The use of bank-side storage: here water is taken from the River Thames and River Lee into several large Thames-side reservoirs, such as Queen Mary Reservoir that can be seen along the approach to London Heathrow Airport . Service reservoirs store fully treated potable water close to the point of distribution. Many service reservoirs are constructed as water towers , often as elevated structures on concrete pillars where
6150-428: The volume of the largest ponds around Clausthal-Zellerfeld and Hahnenklee. In addition completely different construction materials were employed. In the middle of the dam is a core, up to 11.5 metres thick, made of firmly tamped down, granitic sand. Left and right of that apparently 'normal' dam fill material was used. The up- and downstream sides were given cyclopean stonework walls made of large blocks of granite with
6232-410: The water does not rise to an uncontrollably high level, possibly even pouring over the dam crest. On the Oderteich the spillway is located at the left hand (eastern) end of the dam. In the reservoir in front of the outlet are several stone columns, like standing stones in appearance, about 2.50 metres high and made of granite. They serve to keep ice floes away from the spillway, because these could jam
6314-459: The water flow whilst repairs were carried out to the bottom outlet. The coffer dam must have been demolished immediately after this repair had been completed. As a result of the use of water for electricity generation the Rehberg Ditch drew 200 to 300 litres of water per second continuously from the Oderteich. When the inflow of water is less than its outflow, the water level in the reservoir drops. If there are several months of drought in succession,
6396-412: The water, which tends to partition some elements such as manganese and phosphorus into deep, cold anoxic water during the summer months. In the autumn and winter the lake becomes fully mixed again. During drought conditions, it is sometimes necessary to draw down the cold bottom water, and the elevated levels of manganese in particular can cause problems in water treatment plants. In 2005, about 25% of
6478-401: The wooden conduits were being replaced by a considerably more durable artificial ditch made of earth embankments and dry stone walls. In doing so it was realised that the sand resulting from the weathering of granite, so-called granitgrus , if it was thoroughly tramped down, produced a very good seal. In 1712, the deputy chief miner ( Vizebergmeister ), Caspar Dannenberger, wrote two letters to
6560-476: The world's 33,105 large dams (over 15 metres in height) were used for hydroelectricity. The U.S. produces 3% of its electricity from 80,000 dams of all sizes. An initiative is underway to retrofit more dams as a good use of existing infrastructure to provide many smaller communities with a reliable source of energy. A reservoir generating hydroelectricity includes turbines connected to the retained water body by large-diameter pipes. These generating sets may be at
6642-505: Was deemed unnecessary to have a dam keeper permanently presence on the site. The foundations of the old building can be made out behind the present day National Park bus shelter. In addition there is the former MTV Goslar ski lodge, built at the end of the 1940s and now partly hidden and which can also be booked today as accommodation for self-catering groups. Reservoir A reservoir ( / ˈ r ɛ z ər v w ɑːr / ; from French réservoir [ʁezɛʁvwaʁ] )
6724-518: Was used in several power stations and especially the Samson Pit. The water is still used for this purpose today and guarantees the economic operation and maintenance of the Oderteich and Rehberg Ditch. In the late 1920s the Harzwasserwerke planned a further significant increase in the height of the Oderteich Dam. The dam and the geology of the surrounding area were thoroughly examined. Digging exposed
#182817