{{For|the eponymous village in the Vysočina Region|Dolní Heřmanice}} {{Infobox river | name = Oslava | image = Oslava river near Motorpal in Velké Meziříčí, Žďár nad Sázavou District.jpg | image_caption = The Oslava in Velké Meziříčí | source1_location = Matějov, Křižanov Highlands | source1_coordinates = {{coord|49|33|3|N|15|53|57|E|display=inline}} | mouth_location = Jihlava | mouth_coordinates = {{coord|49|5|51|N|16|21|51|E|display=it}} | progression = {{RJihlava}} | subdivision_type1 = Country | subdivision_name1 = Czech Republic | subdivision_type2 = Regions | subdivision_name2 = {{hlist|Vysočina|South Moravian}} | length_km = 101.2 | source1_elevation = {{cvt|584|m}} | mouth_elevation = {{cvt|205|m}} | discharge1_avg = {{convert|3.47|m3/s|abbr=on}} near estuary | basin_size_km2 = 867.0 }} The '''Oslava''' is a river in the Czech Republic, a left tributary of the Jihlava River. It flows through the Vysočina and South Moravian regions. At {{convert|101.2|km|abbr=on}}, it is the 24th longest river in the Czech Republic.
==Etymology== The first written mention of the river is from 1146, when it was called ''Ozlawa'' in a Latin text.<ref>{{cite web |title=Historie města|url=https://www.namestnosl.cz/historie%2Dmesta/d-2730|publisher=Náměšť nad Oslavou|language=cs|access-date=2025-09-13}}</ref> According to one theory, the name is derived from the old Czech word ''osla'', which meant 'grind' and referred to the stones suitable for grinding that were found in the river. According to another theory, the name comes from the Celtic (Gaelic) ''òs, òsa'', meaning 'slow flowing water'.<ref>{{cite web |last=Svoboda|first=Jiří|title=O původu názvů českých řek|url=https://sites.google.com/site/bskotyz/home/jiri-svoboda/o-puavodu-nazvua-rek|language=cs|date=2011-09-08|access-date=2019-07-12|archive-url=https://web.archive.org/web/20201025122958/https://sites.google.com/site/bskotyz/home/jiri-svoboda/o-puavodu-nazvua-rek|archive-date=2020-10-25}}</ref>
==Characteristic== thumb|The Oslava in Oslavany The Oslava originates in the territory of Matějov in the Křižanov Highlands at an elevation of {{cvt|584|m}} and flows to Ivančice, where it enters the Jihlava River at an elevation of {{cvt|205|m}}. It is {{convert|101.2|km|abbr=on}} long, which makes it the 24th longest river in the Czech Republic. Before the remeasurement, its length was stated as 99.2 km until 2013 and then 99.6 km until 2021. After a survey by hydrologists, the location of the spring was specified according to the most abundant source and the length of the entire river was redefined.<ref>{{cite web |last=Bárta|first=Jiří|title=O pramen Oslavy, který je jinde, než určil Zeman, budou pečovat skauti|url=https://www.idnes.cz/jihlava/zpravy/pramen-reka-oslava-skaut-cisteni-priroda-les-ceska-mez-vysocina.A210505_606642_jihlava-zpravy_mv|work=iDNES.cz|language=cs|date=2021-05-08|access-date=2023-09-12}}</ref> Its drainage basin has an area of {{convert|867.0|km2|abbr=on}}.<ref name=dibavod>{{cite web |title=Základní charakteristiky toku Oslava a jeho povodí|url=https://www.dibavod.cz/download.php?id_souboru=2416|publisher=T. G. Masaryk Water Research Institute|language=cs|access-date=2025-06-02}}</ref>
The longest tributaries of the Oslava are:<ref>{{cite web |title=Vodní toky|url=https://mapy.chmi.cz/ords/chmi_app/r/fewshlprf/stream-list?|work=Evidence hlásných profilů|publisher=Czech Hydrometeorological Institute|language=cs|access-date=2025-08-13}}</ref> {| class="wikitable" |- ! Tributary !! Length (km) !! River km !! Side |- | Balinka || 31.1 || 60.3 || right |- | Chvojnice || 21.0 || 17.6 || left |- | Bohdalovský potok || 17.0 || 83.0 || right |- | Oslavička || 15.1 || 58.1 || right |- | Okarecký potok || 13.0 || 32.6 || right |- | Jasinka || 12.8 || 39.4 || left |- | Babačka || 10.7 || 70.6 || left |- | Polomina || 10.4 || 47.3 || left |}
==Course== thumb|Confluence of the Oslava (in front) with the Jihlava The largest town on the river is Velké Meziříčí. The river flows through the following settlements: Nové Veselí, Ostrov nad Oslavou, Velké Meziříčí, Náměšť nad Oslavou, Oslavany and Ivančice.
==Bodies of water== The Mostiště Reservoir with an area of {{cvt|88|ha}} is constructed on the river and is the largest body of water in the basin area. A notable body of water is also the fishpond Veselský rybník with an area of {{cvt|81|ha}}.<ref name=dibavod/>
==Fauna== There were recorded 16 species of aquatic molluscs in the Oslava river: 8 species of gastropods and 8 species of bivalves. There lives endangered species of bivalve ''Unio crassus'' at the lower river section.<ref>{{cite journal |last=Beran|first=Luboš|date=2019-02-09|title=Vodní měkkýši Oslavy [Aquatic molluscs of the Oslava River]|url=https://mollusca.sav.sk/pdf/18/18.Beran.htm|journal=Malacologica Bohemoslovaca|language=cs|volume=18|pages=8–12|doi=10.5817/MaB2019-18-8|issn=1336-6939|doi-access=free}}</ref>
==Tourism== The Oslava is suitable for river tourism. About 88 km of the river is navigable.<ref>{{cite web |title=Řeka Oslava – oblíbená řeka Českomoravské vrchoviny|url=https://www.kudyznudy.cz/aktivity/reka-oslava|publisher=CzechTourism|language=cs|access-date=2023-09-12}}</ref><ref>{{cite web |title=Oslava – česká divočina|url=https://www.padler.cz/vodacky-pruvodce/oslava-ceska-divocina/|publisher=Pádler|language=cs|date=2017-11-11|access-date=2023-09-12}}</ref>
==References== {{reflist}}
==External links== {{commons category|Oslava}} *[https://hydro.chmi.cz/hppsoldv/popup_hpps_prfdyn.php?seq=307000 River flow at Oslavany station] – Flood Warning and Forecasting Service of the Czech Hydrometeorological Institute
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Category:Rivers of the Vysočina Region Category:Rivers of the South Moravian Region Category:Rivers of the Czech Republic