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{{Short description|Natural opening where surface water enters caves}}
{{Short description|Natural opening where surface water enters caves}}
{{other uses|Ponor (disambiguation)}}
{{other uses|Ponor (disambiguation)}}
[[File:Djulin ponor jama.jpg|thumb|upright|The [[Dobra (Kupa)|Dobra River]] enters a 17 km long cave system at {{ill|Đulin ponor|hr}} in [[Ogulin]], [[Croatia]].]]
[[File:Ponor Monte de Fóses.jpg|thumb|Ponor Monte de Fóses]]
[[File:Djulin ponor jama.jpg|thumb|upright|The [[Dobra (Kupa)|Dobra River]] enters a 17 km long cave system at Đulin ponor in [[Ogulin]], [[Croatia]].]]
A '''ponor''' is a natural opening where surface water enters into underground passages; they may be found in [[Karst topography|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 [[Spring (hydrology)|springs]], similar to [[estavelle]]s.<ref name=":0">{{Cite book|last=Bonacci|first=Ognjen|url=https://books.google.com/books?id=bhiJ10Xx9VwC|title=Encyclopedia of Caves and Karst Science|date=2004|publisher=Taylor & Francis|isbn=978-1-57958-399-6|editor-last=Gunn|editor-first=John|pages=1282–1284|language=en|chapter=Ponor}}</ref> Morphologically, ponors come in forms of large pits and [[cave]]s, large [[fissure]]s and caverns, networks of smaller cracks, and sedimentary, [[Alluvium|alluvial]] drains.<ref name=":0" />
A '''ponor''' is a natural opening where surface water enters into underground passages; they may be found in [[Karst topography|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 [[Spring (hydrology)|springs]], similar to [[estavelle]]s.<ref name=":0">{{Cite book|last=Bonacci|first=Ognjen|url=https://books.google.com/books?id=bhiJ10Xx9VwC|title=Encyclopedia of Caves and Karst Science|date=2004|publisher=Taylor & Francis|isbn=978-1-57958-399-6|editor-last=Gunn|editor-first=John|pages=1282–1284|language=en|chapter=Ponor}}</ref> Morphologically, ponors come in forms of large pits and [[cave]]s, large [[fissure]]s and caverns, networks of smaller cracks, and sedimentary, [[Alluvium|alluvial]] drains.<ref name=":0" />


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File:Skocjanske-Ponor3.jpg|A ponor where the [[Reka River]] disappears into [[Škocjan Caves]], Slovenia
File:Skocjanske-Ponor3.jpg|A ponor where the [[Reka River]] disappears into [[Škocjan Caves]], Slovenia
File:Risle ponor.jpg|The [[Risle]] River disappears into a ponor between [[Ajou]] and [[La Houssaye]] ([[Eure]], France)
File:Risle ponor.jpg|The [[Risle]] River disappears into a ponor between [[Ajou]] and [[La Houssaye]] ([[Eure]], France)
File:Jakovica, Logatec - požiralnik Pod stenami na Planinskem polju.jpg|One of many: Logatec, [[Slovenia]]
File:Jakovica, Logatec - požiralnik Pod stenami na Planinskem polju.jpg|A man-made ponor in [[Logatec]], [[Slovenia]]
File:Katavothra ponor Nestani-Polje Peloponnes Greece.jpg|In [[Polje]] "[[Argon Pedion]]" (untilled plain). Plain and ponor documented since 2nd century AD by [[Pausanias (geographer)|Pausanias]]
File:Katavothra ponor Nestani-Polje Peloponnes Greece.jpg|In [[Polje]] "[[Argon Pedion]]" (untilled plain). Plain and ponor documented since 2nd century AD by [[Pausanias (geographer)|Pausanias]]
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Latest revision as of 09:05, 3 August 2024

The Dobra River enters a 17 km long cave system at Đulin ponor [hr] in Ogulin, Croatia.

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.[1] Morphologically, ponors come in forms of large pits and caves, large fissures and caverns, networks of smaller cracks, and sedimentary, alluvial drains.[1]

Etymology

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The name for the karst formation ponor comes from Croatian and Slovene.[2] It derives from the proto-Slavic word *nora, meaning pit, hole.[3]

Several places in southeast Europe (Bulgaria, Croatia, Czech Republic, Hungary, Romania, Montenegro, Slovenia) bear the name Ponor due to associated karst openings.

Description

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Whereas a sinkhole (doline) is a depression of surface topography with a pit or cavity directly underneath, a ponor is kind of a portal where a surface stream or lake flows either partially or completely underground into a karst groundwater system.[1] Steady water erosion may have formed or enlarged the portal in (mainly limestone) rock, in a conglomerate, or in looser materials. Karst terrains are known for surface water losses through small ponors and its resurgence after having traveled through vast underground systems.[1]

Prevalence

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Ponors are found worldwide, but only in karst regions. The entire Adriatic watershed within Bosnia and Herzegovina sits on Dinaric karst, with numerous explored and probably many more unexplored ponors and underground flows.[4][5] There are significant geological ponors in the Carpathian Mountains, the Dinaric Alps, Greece, Turkey, and parts of the southern United States.[citation needed]

Dams and reservoirs in karst

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Reservoirs in karst are prone to losses due to leakage through ponors. The construction of dams to capture water in karst terrains may pose a great financial risk despite initial investigations and thorough sealing treatments.[6] It wasn't until the twentieth century that the first dams in karst were built, some of which famously failed.[6]

See also

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References

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  1. ^ a b c d Bonacci, Ognjen (2004). "Ponor". In Gunn, John (ed.). Encyclopedia of Caves and Karst Science. Taylor & Francis. pp. 1282–1284. ISBN 978-1-57958-399-6.
  2. ^ Dicken, Samuel N. (November 1935). "Kentucky Karst Landscapes". The Journal of Geology. 43 (7): 708–728. doi:10.1086/624363. JSTOR 30057941. S2CID 140553389. Since local terms such as "sink," "sink hole", "kettle", "bottom", etc., are vague and confusing the Slovene terminology ("ponor", "doline", etc.) is used for the karst forms.
  3. ^ "Ponor/ponirati". Hrvatski jezični portal. Retrieved 2021-11-03.
  4. ^ "The Karstography of the Dinaric Karst in Bosnia and Hercegovina". The Devon Karst Research Society. Retrieved 4 September 2016.
  5. ^ "The Devon Karst Research Society" (.html). www.devonkarst.org.uk. Devon Karst. Retrieved 4 September 2016.
  6. ^ a b Milanović, Petar (2004). "Dams and reservoirs on karst". In Gunn, John (ed.). Encyclopedia of Caves and Karst Science. Taylor & Francis. pp. 571–575. ISBN 978-1-57958-399-6.