The Fürstenteich is a reservoir near Silberhütte in the German state of Saxony-Anhalt . It has an earth-filled dam with an impervious core. It impounds the Teufelsgrundbach stream.
15-422: The dam was based on sedimented shale and has an internal impervious core of organic clays (grass sods). During renovation work about 70 cm of the surface layer on the old downstream face was removed and replaced by layers of shale material. That was covered with a 10 cm thick layer of topsoil sown with grass seed. On the upstream side, 60 cm was removed and on a 30 cm thick layer of stone chippings
30-443: A knickpoint , water continues to bombard its base. Because this rock is often less resistant than overlying strata, the water from the higher elevation continues eroding downward until an equilibrium is achieved. A somewhat similar bowl-shaped feature developed by flowing water, as opposed to falling water, is known as a scour hole. These occur both naturally and as a result of bridge building . Perth Canyon Perth Canyon
45-629: A naval base at nearby Garden Island . In June 2006 the waters around the Perth Canyon were the site of an ocean vortex 200 kilometres (120 mi) in diameter and 1,000 metres (3,300 ft) deep. It was visible from space, and scientists claimed at the time that it had the potential to affect the local climate and the climate further abroad. The vortex was described by scientists as a marine "death trap", as it sucked in fish larvae. 32°01′S 114°59′E / 32.01°S 114.98°E / -32.01; 114.98 This article about
60-406: A reinforced concrete channel with 18 sections. Its total length is about 95 m. The reservoir was built in 1729 as a stamp mill pond and supplied, together with the higher-situated Teufelsteich , driving water for the silver works in the village of Silberhütte named after the works. The dam faces were relatively steep with an incline of 1:1.7 until the renovation work in 1984. The Fürstenteich
75-413: A similarly thick protective layer of ballast. The dam was also raised in height by about 1 metre. After removing 90 cm of the old dam crest, a metre-wide toe wall was integrated from the subgrade ( Planum ). This extends as far as the cohesive earth material of the old dam core. The old wooden outlet channel ( Striegelgerinne ) is still there, but no longer functioning. It has since been linked to
90-543: Is a submarine canyon located on the edge of the continental shelf off the coast of Perth, Western Australia , approximately 22 kilometres (14 mi) west of Rottnest Island . It was carved by the Swan River , probably before the Tertiary , when this part of the continental shelf was above sea level. It is an average of 1.5 kilometres (5,000 ft) deep and 15 kilometres (9.3 mi) across, making it similar in dimension to
105-522: Is a deep depression in a stream bed at the base of a waterfall or shut-in . It is created by the erosional forces of cascading water on the rocks at the formation's base where the water impacts. The term may refer to the water occupying the depression, or the depression itself. Plunge pools are formed by the natural force of falling water, such as at a waterfall or cascade; they also result from man-made structures such as some spillway designs. Plunge pools are often very deep, generally related to
120-483: The Channeled Scablands of eastern Washington . They can also be found underwater in areas that were formerly above sea level, for example, Perth Canyon off the coast of Western Australia . Plunge pools are fluvial features of erosion which occur in the youthful stage of river development, characterized by steeper gradients and faster water flows. Where softer or fractured rock has been eroded back to
135-500: The Grand Canyon . It occupies an area of 2,900 square kilometres (1,100 sq mi) and ranges in depth from 700 to 4,000 metres (2,300 to 13,100 ft). Within a few kilometres its depth drops from 200 metres (660 ft) down to 1,000 metres (3,300 ft), and then it continues as a deep gully all the way out to the 4,000-metre (13,000 ft) depth, which is about another 30 kilometres (20 mi) farther west. It contains
150-695: The Silberhütter Pochwerksteich were additionally supplied with water from the Lude stream and the Rödelbachgraben . When the silver works went bankrupt in 1937 the reservoir was used to generate electricity until 1939 and then the ditch was drained dry. The reservoir was used from 1937 to 1997 for the supply of drinking water. In 1980 the first problems arose on the dam which had now become overgrown with trees and bushes. The bottom outlet no longer work and seepage began to occur in places. From 1984 to 1987
165-652: The dam was overhauled and the faces relaid at an incline of 1:2. The last renovations took place in 1997 and 1999, when a new bottom outlet was fitted and the dam crest replace. Due to subsidence on the upstream side of the dam the water level dropped by about a metre. The pond may be reached from the neighbouring Teufelsteich over hiking trails and is used for water management, angling and recreation. Talsperren in Sachsen-Anhalt, Autorenkollegium, Hrsg. Talsperrenmeisterei des Landes Sachsen-Anhalt 1994 Plunge pool A plunge pool (or plunge basin or waterfall lake )
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#1732892024931180-423: The height of the fall, the volume of water, the resistance of the rock below the pool and other factors. The impacting and swirling water, sometimes carrying rocks within it, abrades the riverbed into a basin, which often features rough and irregular sides. Plunge pools can remain long after the waterfall has ceased flow or the stream has been diverted. Several examples of former plunge pools exist at Dry Falls in
195-405: The seepage water measurement shaft ( Sickerwasser-Messschacht ) by a steel pipe. During the construction phase in 1903/04 a cast iron siphon pipe was laid, which crossed the spillway. The siphon pipe has a vent in the concrete ring on the dam crest. In 1990 the cast iron ring was cut by the spillway and has since emptied via a new outlet into the plunge pool of the spillway. The spillway consists of
210-510: The world's largest plunge pool —a depression in the canyon that is 2 kilometres (1.2 mi) long, 6 kilometres (3.7 mi) across, and 300 metres (980 ft) deep. The canyon is considered "a perfect spot" for deep sea fishing. The Perth Canyon is a feeding ground for pygmy blue whales , especially at the rims of the abyss. It is also a training ground for the Royal Australian Navy Submarine Service , stationed at
225-752: Was first linked into the Lower Harz Pond and Ditch System in 1903/04, when the dam was raised for the first time. The Kochsgraben was extended for the last time and now ended in the catchment area of the Teufelsteich , the Siebengrund bottom. This extension was called the Siebengründer Graben ; at the same time the section to Neudorf was drained dry. Now the Teufelsteich as well as the Fürstenteich and
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