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Sump (cave)
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 an 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 factors specific to a cave – such as the sea tide, changes in river flow, or the relationship with the local water table – 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 in Swildon's Hole). 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 requirin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrology
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 drainage basin sustainability. A practitioner of hydrology is called a hydrologist. Hydrologists are scientists studying earth science, earth or environmental science, civil engineering, civil or environmental engineering, and physical geography. Using various analytical methods and scientific techniques, they collect and analyze data to help solve water related problems such as Environmentalism, environmental preservation, natural disasters, and Water resource management, water management. Hydrology subdivides into surface water hydrology, groundwater hydrology (hydrogeology), and marine hydrology. Domains of hydrology include hydrometeorology, surface-water hydrology, surface hydrology, hydrogeology, drainage basin, drainage-basin management, and water quality. Oceanography and meteorology are not included beca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can be used for any given locale to find the predicted times and amplitude (or " tidal range"). The predictions are influenced by many factors including the alignment of the Sun and Moon, the phase and amplitude of the tide (pattern of tides in the deep ocean), the amphidromic systems of the oceans, and the shape of the coastline and near-shore bathymetry (see '' Timing''). They are however only predictions, the actual time and height of the tide is affected by wind and atmospheric pressure. Many shorelines experience semi-diurnal tides—two nearly equal high and low tides each day. Other locations have a diurnal tide—one high and low tide each day. A "mixed tide"—two uneven magnitude tides a day—is a third regular category. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subterranean River
A subterranean river (also known as an underground river) is a river or watercourse that runs wholly or partly beneath the ground, one where the riverbed does not represent the surface of the Earth. It is distinct from an aquifer, which may flow like a river but is contained within a permeable layer of rock or other unconsolidated materials. A river flowing below ground level in an open gorge is not classed as subterranean. Some natural rivers may be entirely subterranean, collecting in and flowing through cave systems. In karst topography, rivers that originate above ground can disappear into sinkholes, continuing underground until they reappear on the surface downstream, possibly having merged with other subterranean rivers. The longest subterranean river in the world is the Sistema Sac Actun cave system in Mexico. Subterranean rivers can also be the result of covering over a river or diverting its flow into culverts, usually as part of urban development.Richard J. Heggen: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Table
The water table is the upper surface of the phreatic zone or zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the locality. It can also be simply explained as the depth below which the ground is saturated. The portion above the water table is the vadose zone. It may be visualized as the "surface" of the subsurface materials that are saturated with groundwater in a given vicinity. In coarse soils, the water table settles at the surface where the water Hydraulic head, pressure head is equal to the atmospheric pressure (where gauge pressure = 0). In soils where capillary action is strong, the water table is pulled upward, forming a capillary fringe. The groundwater may be from precipitation or from more distant groundwater flowing into the aquifer. In areas with sufficient precipitation, water infiltrates through pore spaces in the soil, passing through t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swildon'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 (SSSI). The upper series of the cave compresses many features into a relatively short space. The cave goes far beyond this, however, and the lower reaches of the cave continue to provide challenges for even the most experienced of cave divers. The name may be a corruption of Swithun, an Anglo-Saxon bishop of Winchester, as the land in the area was owned by St Swithin's Priory in Winchester. History The cave was first entered on 16 August 1901 by members of the Wells Natural History and Archaeological Society. Very rapid progression was made to what is now known as the 40 foot pot. Between 1903 and 1910, in spite of access being banned by the landowner, various trips took place to photograph and explore the passages. In 1914 the limit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 underwater search and recovery, search for and recovery of divers or, as in the Tham Luang cave rescue, 2018 Thai cave rescue, other cave users. The equipment used varies depending on the circumstances, and ranges from Free-diving, breath hold to Surface-supplied diving, surface supplied, but almost all cave-diving is done using scuba equipment, often in specialised configurations with engineering redundancy, redundancies such as Sidemount diving, sidemount or backmounted twinset. Recreational cave-diving is generally considered to be a type of technical diving due to the lack of a free surface during large parts of the dive, and often involves planned Decompression (diving), decompression stops. A distinction is made by recreational diver training agencies between cave-diving and cavern-diving, where cavern diving i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Krubera Cave
Krubera Cave ( Abkhaz: Ӡоу Аҳаҧы; ka, კრუბერის გამოქვაბული or კრუბერის ღრმული, tr; also known as Voronya Cave, sometimes spelled Voronja Cave) is the deepest known cave on Earth. It is located in the Arabika Massif of the Gagra Range of the Western Caucasus, in the Gagra District of Abkhazia, a disputed region of Georgia (country), Georgia. The difference in elevation of the highest cave entrance (Arbaika) and its deepest explored point is . It became the deepest known cave in the world in 2003 when the Ukrainian Speleological Association reached a depth of . This exceeded the previous record, Lamprechtsofen in the Austrian Alps, by . In 2006, for the first time in the history of speleology, the Ukrainian Speleological Association expedition reached a depth greater than 2,000 m (6,560 ft), and explored the cave to . Ukrainian diver Gennadiy Samokhin extended the cave by diving in the termina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphon
A siphon (; also spelled 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 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. There are two leading theories about how siphons cause liquid to flow uphill, against gravity, without being pumped, and powered only by gravity. The traditional theory for centuries was that gravity pulling the liquid down on the exit side of the siphon resulted in reduced pressure at the top of the siphon. Then atmospheric pressure was able to push the liquid from the upper reservoir, up into the reduced pressure at the top of the siphon, like in a barometer or drinking straw, and then over. However, it has been demo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinkhole Dersios
The Dersios sinkhole (Greek: Σπηλαιοκαταβόθρα "Ο Δέρσιος" ''Spilaiokatavothra "O Dhersios"'') is a sinkhole in Arcadia (regional unit), Arcadia, Greece. The sinkhole, which has a depth of , has been known since antiquity and is located towards the north end of the plateau of Palaiochora Tyrou, Palaiochora at a height of 750 m above sea level on mount Parnon. It is about 45 minutes on unsurfaced road from the nearest town of Tyros,_Greece, Tyros in the Kynouria region of Arcadia. The sinkhole was first explored in August 1974 to a depth of by a French team (in collaboration with the Hellenic Speleological Society). Since 2003, SELAS caving club in Greece has been exploring the cave, doubling the depth and more than tripling the length of the sinkhole. The new discoveries were made in 2003 by cave diving the first Sump (cave), sump and emptying it by siphoning the water and in 2005 by emptying sumps in side passages of the sinkhole. References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 also known as shakeholes, and to openings where surface water enters into underground passages known as ''ponor'', swallow hole or swallet. A ''cenote'' is a type of sinkhole that exposes groundwater underneath. ''Sink'', and ''stream sink'' are more general terms for sites that drain surface water, possibly by infiltration into sediment or crumbled rock. Most sinkholes are caused by Karst topography, karst processes – the chemical dissolution of carbonate rocks, collapse or suffosion processes. Sinkholes are usually circular and vary in size from tens to hundreds of Metre, meters both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide. Formation Natural processes Sinkholes may capture surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
