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A sump, or siphon, is a passage in a cave that is submerged under water. A sump may be static, with no inward or outward flow, or active, with continuous through-flow. Static sumps may also be connected underwater to active stream passage. When short in length, a sump may be called a duck, however this can also refer to a section or passage with some (minimal) airspace above the water.
Depending on
Sump Rescue
{{caves Caving Hydrology
A sump, or siphon, is a passage in a cave that is submerged under water. A sump may be static, with no inward or outward flow, or active, with continuous through-flow. Static sumps may also be connected underwater to active stream passage. When short in length, a sump may be called a duck, however this can also refer to a section or passage with some (minimal) airspace above the water.
Depending on hydrological
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is calle ...
factors specific to a cave – such as the sea tide, changes in river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
flow, or the relationship with the local water table
The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated.
T ...
– sumps and ducks may fluctuate in water level and depth (and sometimes in length, due to the shape of adjacent passage).
Exploration past a sump
Diving
Short sumps may be passed simply by holding one's breath while ducking through the submerged section (for example, Sump 1 inSwildon's Hole
Swildon's Hole is an extensive cave in Priddy, Somerset. At in length, it is the longest cave on the Mendip Hills. It has been found to be connected to Priddy Green Sink and forms part of the Priddy Caves Site of Special Scientific Interest ( ...
). This is known as "free diving" and can only be attempted if the sump is known to be short and not technically difficult (e.g. constricted or requiring navigation). Longer and more technically difficult sumps can only be passed by cave diving
Cave-diving is underwater diving in water-filled caves. It may be done as an extreme sport, a way of exploring flooded caves for scientific investigation, or for the search for and recovery of divers or, as in the 2018 Thai cave rescue, other ...
(as happened repeatedly in the exploration of Krubera Cave
Krubera Cave ( ab, Ӡоу Аҳаҧы, ka, კრუბერის გამოქვაბული or კრუბერის ღრმული, tr; also known as Voronya Cave, sometimes spelled Voronja Cave) is the second-deepest-known c ...
).
Draining
When practical, a sump can also be drained using buckets, pumps orsiphon
A siphon (from grc, σίφων, síphōn, "pipe, tube", also spelled nonetymologically syphon) 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 a ...
s. Pumping the water away requires the inward flow of water into the sump to be less than the rate at which the pump empties it, as well as a suitable place to collect the emptied water. Upstream sumps have been successfully emptied using hoses to siphon water out of them, such as at the Sinkhole Dersios
The Dersios sinkhole (Greek: Σπηλαιοκαταβόθρα "Ο Δέρσιος" ''Spilaiokatavothra "O Dhersios"'') is a sinkhole in Arcadia, Greece.
The sinkhole, which has a depth of , has been known since antiquity and is located towards th ...
during exploration in 2005. The water was sent deeper into the sinkhole
A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...
, and the emptied sumps revealed virgin passage behind them. During a rescue from beyond a downstream sump at Sarkhos Cave in 2002, water was pumped upstream into a dam
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...
constructed a few metres above the flooded passage.
Some manuals also mention the use of explosives
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
or other forms of force to empty sumps, but the ecological damage done to the fragile cave environment usually rules out the use of such methods.
See also
*External links
Sump Rescue
{{caves Caving Hydrology