Lake Cerknica

{{Infobox body of water

| name = Lake Cerknica

| image = SlikaCerkniskoJezeroPolno.jpg

| caption = Lake Cerknica after rain

| image_bathymetry =

| caption_bathymetry =

| location = Inner Carniola

| coords = {{coord|45|45|08|N|14|23|06|E|region:SI_type:waterbody_source:dewiki|display=inline,title}}

| type = intermittent

| inflow =

| outflow =

| catchment =

|pushpin_map=Slovenia

| basin_countries = Slovenia

| length =

| width =

| area = {{convert|38|km2|abbr=on}} (max.)

| depth = {{convert|10|m|abbr=on}} (max.)

| max-depth =

| volume =

| residence_time =

| shore =

| elevation = {{convert|546|to|551|m|abbr=on}}

| frozen =

| islands =

| cities = Cerknica, Dolenje Jezero, Gorenje Jezero, Grahovo

| reference =

| embedded = {{Designation list

| embed = yes

| designation1 = Ramsar

| designation1_offname = Cerkniško jezero z okolico

| designation1_date = 19 January 2006

| designation1_number = 1600{{Cite web|title=Cerkniško jezero z okolico|website=Ramsar Sites Information Service|url=https://rsis.ramsar.org/ris/1600|access-date=25 April 2018}}}}

}}

Lake Cerknica ({{IPA|sl|ˈtseːɾknitsa|pron}}; {{langx|sl|Cerkniško jezero}}) is an intermittent lake in the southern part of the Cerknica Polje, a karst polje in Inner Carniola, a region in southwestern Slovenia.{{cite encyclopedia |url=http://www.dedi.si/dediscina/9-cerknisko-polje |title=Cerkniško polje |trans-title=Cerknica Polje |encyclopedia=Enciklopedija naravne in kulturne dediščine na Slovenskem [Encyclopedia of Natural and Cultural Heritage in Slovenia] |first=Janez |last=Turk |editor1-last=Šmid Hribar |editor2-first=Gregor |editor2-last=Golež |editor3-first=Dan |editor3-last=Podjed |editor4-first=Drago |editor4-last=Kladnik |editor5-first=Bojan |editor5-last=Erhartič |editor6-first=Primož |editor6-last=Pavlin |editor7-first=Jerele |editor7-last=Ines |access-date=17 May 2012 |language=sl}}

Description

The lake, oriented in the Dinaric direction from north-west to south-east, is present for the most part of the year. When full, it is the largest lake in the country. The plain is surrounded by the Javornik Hills ({{convert|1268|m|disp=or}}) to the south and Slivnica ({{convert|1022|m|disp=or|abbr=on}}) to the north, both belonging to Dinaric Alps. The area of the lake mainly reaches {{convert|28|km2}}, but can reach up to {{convert|38|km2|abbr=on}} and the surface level varies from {{convert|546|m|abbr=on}} to {{convert|551|m|abbr=on}} above sea level. The largest settlement at the border of the lake is Cerknica, located north of the lake. Various watersports, including rowing, are popular on the lake.{{cite web|title=Boating|url=http://www.notranjski-park.si/en/visit-us/activities/boating|website=Notranjski park|access-date=13 April 2018|language=en}}

Environment

The climate in the area is continental, with a mean temperature of {{convert|9.2|C}} and the annual precipitation about {{convert|1700|mm}}. Botanically, the lake is distinguished by amphibious plants. It is therefore a part of two Natura 2000 areas of protection[http://life.notranjski-park.si/index.php?catid=43&lang=slo Projektno območje] {{Webarchive|url=https://web.archive.org/web/20110820014746/http://life.notranjski-park.si/index.php?catid=43&lang=slo |date=2011-08-20 }}. Project Life. Notranjska Regional Park. Accessed 2009-12-16. (in Slovene) and the focus of the Inner Carniola Regional Park, which covers additional Natura 2000 areas in the broader region.[http://www.notranjski-park.si/eng/zlozenka-ang-1-2008.pdf Notranjska Regional Park] {{webarchive|url=https://web.archive.org/web/20111006173631/http://www.notranjski-park.si/eng/zlozenka-ang-1-2008.pdf |date=2011-10-06 }} - informative leaflet. Accessed 2009-12-16. The lake is an important wildlife resource, especially as a nesting place for many bird species. It has been designated an Important Bird Area (IBA) by BirdLife International.{{cite web |url= https://datazone.birdlife.org/site/factsheet/lake-cerknica-iba-slovenia |title=Lake Cerknica|author= |date=2024|website= BirdLife Data Zone|publisher= BirdLife International|access-date= 2024-09-04}}

=Intermittency=

The lake, which under ordinary conditions has an area of about {{convert|10|sqmi|order=flip|abbr=on}} and a mean depth of {{convert|20|ft|order=flip|abbr=on}}, communicates through a number of openings with a series of subterranean reservoirs or caverns, some of which are above the lake level in the surrounding hills. In the summer, when the rainfall is slight, the lake is completely drained into the reservoirs lying below its level, and its bed is speedily covered with rich vegetation. With the returning heavy rains in autumn, the surrounding higher reservoirs are filled and discharge suddenly through the subterranean passages into the lake, so that the latter very rapidly regains its ordinary volume and may even inundate the surrounding country. The changes in level are, however, very irregular. Sometimes the lake does not disappear for several years, and it can remain dry for over a year, as it did in 1834–35. It is rich in fish, which disappear and return with the water.{{Cite NIE|wstitle=Zirknitzer See|year=1905}}

Research history

File:Acta Eruditorum - XV geologia acqua, 1689 – BEIC 13398218.jpg, 1689]]

Strabo in his Geography mentions a "marsh called Lugeon" (helos Lougeon kaloumenon) which has been identified with Lake Cerknica,Strabo, [https://www.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus:text:1999.01.0198:book=7:chapter=5:section=1 Strabo, Geography, v. 7, ch. 5] at perseus.tufts.edu Lougeon being Strabo's Greek rendition of a local toponym, perhaps of Illyrian origin. It is Romanized as Lugeum. In November 1687 the Carniolan polymath Johann Weikhard von Valvasor{{Cite book|url=http://atena.beic.it/webclient/DeliveryManager?pid=13398218&search_terms=DTL194|title=Lacus Cirknicensis potiora phaenomena ex principiis physicis et mathematicis explanata|work=Acta Eruditorum|year=1689|location=Leipzig|pages=634 [i.e. 614]}} described the lake in his letter to the Royal Society, an excerpt of which was published in the Society's Philosophical Transactions in December that year.{{cite book |url=http://sistory.si/publikacije/prenos/?urn=SISTORY:ID:14647#page=197 |title=Kranjski polihistor Janez Vajkard Valvasor |trans-title=The Carniolan Polymath Johann Weikhard von Valvasor |first=Branko |last=Reisp |year=1983 |id={{COBISS|ID=13772033}} |publisher=Mladinska knjiga |language=sl|pages=177–184}} He proposed a model of filling and emptying the lake, based on Cartesian mechanics.{{cite journal |last=Weichard |first=John |author-link=Janez Vajkard Valvasor |year=1686–1692 |title=An Extract of a Letter written to the Royal Society out of Carniola, by Mr. John Weichard Valvaſor, R. Soc. S. being a full and accurate deſcription of the wonderful Lake of Zirknitz in that Country |jstor=101905 |journal=Philosophical Transactions |volume=16 |pages=411–427 |doi=10.1098/rstl.1686.0074|doi-access=free }}{{cite book|last1=Shaw|first1=Trevor|last2=Čuk|first2=Alenka|title=Slovene Karst and Caves in the Past|date=2015|publisher=Založba ZRC|isbn=9789612547400|page=124|url=https://books.google.com/books?id=7a6TCwAAQBAJ&q=Valvasor&pg=PA124|language=en}} The first to accurately describe the functioning of Lake Cerknica was Tobias Gruber in 1781,{{cite journal |url=http://www.dlib.si/details/URN:NBN:SI:DOC-YHPGDBBO/?=&language=eng |title=Raziskovanje vodnih jam na Slovenskem: pregled od antike do danes |language=sl |trans-title=The Exploration of Water Caves in the Slovene Lands: An Overview from Antiquity until Today |year=1984 |volume=32 |issue=1 |first=Andrej |last=Kranjc |journal=Kronika |publisher=Section for the History of Places, Association of Historical Societies of Slovenia |issn=0023-4923 |pages=35–43}} followed in 1784 by Belsazar Hacquet.{{cite encyclopedia |url=http://www1.dedi.si/dediscina/287-geologija-alpskega-sveta-slovenije |title=Geologija alpskega sveta Slovenije |trans-title=The Geology of the Alpine Landscapes of Slovenia |encyclopedia=Enciklopedija naravne in kulturne dediščine na Slovenskem – DEDI [Encyclopedia of Natural and Cultural Heritage in Slovenia] |first1=Ines |last1=Jerele |editor1-first=Mateja |editor1-last=Šmid Hribar |editor2-first=Gregor |editor2-last=Golež |editor3-first=Dan |editor3-last=Podjed |editor4-first=Drago |editor4-last=Kladnik |editor5-first=Bojan |editor5-last=Erhartič |editor6-first=Primož |editor6-last=Pavlin |editor7-first=Jerele |editor7-last=Ines |access-date=25 July 2012 |language=sl }}{{Dead link|date=February 2020 |bot=InternetArchiveBot |fix-attempted=yes }}