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The Vipava (in Slovene) or Vipacco (in Italian) or Wipbach / Wippach (in German) is a river that flows through western Slovenia and northeast Italy. The river is 49 kilometres (30 mi) in length. After entering Italy it joins the Isonzo/Soča in the Municipality of Savogna d'Isonzo. This is a rare river with a delta source, formed by nine main springs. The Battle of the Frigidus was fought near the river, which was named Frigidus ('cold') by the Romans. It has the pluvial-nival regime in its upper course and the pluvial regime in its lower course.
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- ^ Brečko Grubar,, Valentina; Kovačič, Gregor (2010). "Pokrajinskoekološka oznaka jadranskega povodja v Sloveniji s poudarkom na kakovosti vodnih virov" [Landscape Ecological Characterization of the Adriatic Sea Basin in Slovenia with an Emphasis on Water Resource Quality]. Annales. Series historia et sociologia (in Slovenian) 20 (1): 153–168.
Coordinates: 45°54′N 13°33′E / 45.900°N 13.550°E