A rhythmic spring (also: ebb and flow spring, periodic spring, intermittent spring) is a cold water spring from which the flow of water either varies or starts and stops entirely, over a fairly regular time-scale of minutes or hours. Compared to continuously-flowing springs, rhythmic springs are uncommon, with the number worldwide estimated in 1991 to be around one hundred. [1]
Although the cause of the periodicity in flow is not known for certain, the most accepted theory (first postulated in the early 18th century) is that as groundwater flows continuously into a cavern, it fills a narrow tube that leads upwards from near the base of the cavern, then downwards to the spring. As the water level reaches the high point of the tube, it creates a siphon effect, sucking water out of the chamber. Eventually air rushes into the tube and breaks the siphon, stopping the flow if there is no other source feeding the spring, or reducing the flow if there is a continuous flow from another non-siphon source. [2]
In 2006 the University of Utah studied the Intermittent Spring in Swift Creek canyon in Star Valley, Wyoming, United States. Kip Solomon, a hydrologist at the University concluded that "The spring water's gas content has now been tested [...]. The data strongly suggests the water was exposed to air underground; strong support for the siphon theory." [3]
The Intermittent Spring in Wyoming, mentioned above, is the largest rhythmic spring in the world.
The Gihon Spring in the City of David in Jerusalem used to be a rhythmic spring before modern-time overpumping affected the level of the underground water table. It was of great historical, archaeological, and cultural importance because it is what made possible the human settlement in ancient Jerusalem.
Pliny the Younger – who is famous for his accurate description of the Vesuvius eruption of AD 79 – also accurately described a rhythmic spring in the last letter of Book IV. [4] This rhythmic spring is still acting to the same time scale today (Villa Pliniana spring in Como, Italy).
In Serbia there are four intermittent springs:
A peristaltic pump, also commonly known as a roller pump, is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained in a flexible tube fitted inside a circular pump casing. Most peristaltic pumps work through rotary motion, though linear peristaltic pumps have also been made. The rotor has a number of "wipers" or "rollers" attached to its external circumference, which compress the flexible tube as they rotate by. The part of the tube under compression is closed, forcing the fluid to move through the tube. Additionally, as the tube opens to its natural state after the rollers pass, more fluid is drawn into the tube. This process is called peristalsis and is used in many biological systems such as the gastrointestinal tract. Typically, there will be two or more rollers compressing the tube, trapping a body of fluid between them. The body of fluid is transported through the tube, toward the pump outlet. Peristaltic pumps may run continuously, or they may be indexed through partial revolutions to deliver smaller amounts of fluid.
A spring is a natural exit point at which groundwater emerges out of the aquifer and flows onto the top of the Earth's crust (pedosphere) to become surface water. It is a component of the hydrosphere, as well as a part of the water cycle. Springs have long been important for humans as a source of fresh water, especially in arid regions which have relatively little annual rainfall.
A siphon is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at a level lower than the surface of the reservoir from which it came.
A cenote is a natural pit, or sinkhole, resulting when a collapse of limestone bedrock exposes groundwater. The term originated on the Yucatán Peninsula of Mexico, where the ancient Maya commonly used cenotes for water supplies, and occasionally for sacrificial offerings. The name derives from a word used by the lowland Yucatec Maya—tsʼonoʼot—to refer to any location with accessible groundwater.
A show cave—also called tourist cave, public cave, and, in the United States, commercial cave—is a cave which has been made accessible to the public for guided visits.
Gihon Spring or Fountain of the Virgin, also known as Saint Mary's Pool, is a spring in the Kidron Valley. It was the main source of water for the Pool of Siloam in Jebus and the later City of David, the original site of Jerusalem.
The Jeita Grotto is a system of two separate, but interconnected, karstic limestone caves spanning an overall length of nearly 9 kilometres (5.6 mi). The caves are situated in the Nahr al-Kalb river valley within the locality of Jeita, 18 kilometres (11 mi) north of the Lebanese capital Beirut. Though inhabited in prehistoric times, the lower cave was not rediscovered until 1836 by Reverend William Thomson; it can only be visited by boat since it channels an underground river that provides fresh drinking water to more than a million Lebanese.
The Judaean Desert or Judean Desert is a desert in the West Bank and Israel that lies east of the Judaean Mountains, so east of Jerusalem, and descends to the Dead Sea. Under the name El-Bariyah, it has been nominated to the Tentative List of World Heritage Sites in the State of Palestine, particularly for its monastic ruins.
Sinks Canyon State Park is a public recreation and nature preservation area located in the Wind River Mountains, six miles (9.7 km) southwest of Lander, Wyoming, on Wyoming Highway 131. The state park is named for a portion of the Middle Fork of the Popo Agie River where it flows into an underground limestone cavern, named "the Sinks," and emerges a quarter-mile down the canyon in a pool named "the Rise." The park is managed by the Wyoming Division of State Parks and Historic Sites.
Honey Creek is a 20.3-mile-long (32.7 km) tributary of Kishacoquillas Creek that is located in Mifflin County, Pennsylvania in the United States.
The Great Wold Valley is the largest and broadest of the valleys cutting into the Yorkshire Wolds in northern England. It carries the Gypsey Race, an intermittent stream, which runs from its source near Wharram-le-Street eastwards along and through the northern Yorkshire Wolds to reach the sea at Bridlington.
The Lost River is a river that rises in Vernon Township, Washington County, Indiana, and discharges into the East Fork of the White River in Lost River Township, Martin County, Indiana. The river's unusual hydrology has led to two of its features being named as National Natural Landmarks.
A ponor is a natural opening where surface water enters into underground passages; they may be found in karst landscapes where the geology and the geomorphology is typically dominated by porous limestone rock. Ponors can drain stream or lake water continuously or can at times work as springs, similar to estavelles. Morphologically, ponors come in forms of large pits and caves, large fissures and caverns, networks of smaller cracks, and sedimentary, alluvial drains.
A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks.
Škocjan Caves is a cave system located in Slovenia. Recognized for its exceptional significance, Škocjan Caves was included on UNESCO’s list of natural and cultural World Heritage Sites in 1986. Škocjan Caves is a significant underground phenomenon on the Karst Plateau and in Slovenia. After gaining independence from Yugoslavia in 1991, Slovenia made a commitment to actively protect the Škocjan Caves area. To fulfill this commitment, Škocjan Caves Regional Park was established, along with its managing authority, the Škocjan Caves Park Public Service Agency.
The Rio Hondo is a 79-mile-long (127 km) river in southern New Mexico which begins at the confluence of the Rio Bonito and Rio Ruidoso rivers near the town of Hondo, New Mexico. The river flows eastward through the Hondo Valley in the foothills of the Sierra Blanca and Capitan Mountains, roughly paralleling the route of U.S. Route 70 through the towns of Picacho and Tinnie. Near the community of Riverside the river passes through a deep canyon before entering the rolling hills west of Roswell.
A karst spring or karstic spring is a spring that is part of a karst hydrological system.
Intermittent Spring, also called Periodic Spring, is located in Swift Creek canyon in Star Valley, near Afton, Wyoming. It is the largest rhythmic spring in the world.
The Ombla is a short river in Croatia, northeast of Dubrovnik. Its course is approximately 30 metres long, and it empties into the Rijeka Dubrovačka, ria formed by the Adriatic Sea near Komolac in Dubrovnik-Neretva County. Rijeka Dubrovačka is actually a ria, a flooded river valley formed through changes in sea surface elevation on a geologic time scale. The river rises as a karst spring fed by groundwater replenished by Trebišnjica, which is an influent stream flowing in Popovo Polje, in the immediate hinterland of the Ombla. The elevation difference between the river's source and its mouth is just over 2 metres. The average discharge of the river is 24.1 cubic metres per second. The drainage basin of the Ombla encompasses 600 square kilometres and, besides the short surface course, includes only groundwater flow.
Cerje Cave or Cerjanka is a cave in southeast Serbia. With the length of 7,149 m (23,455 ft), it is the second longest cave in Serbia after the 9,818 m (32,211 ft) long Lazar's Cave.