kupa

Kupa is a river in Slovenia and Croatia, part of the Sava river basin in the Danube system. It originates in the western part of Slovenia, in the Alps region, and flows generally southeast across the border into Croatia. The river's course traverses varied landscapes, including highland areas, karst features, and agricultural plains, before it empties into the Sava River in Croatia.

The Kupa basin supports diverse habitats and communities; its waters are used for drinking-water supply, irrigation, and hydroelectric power generation, and the surrounding valley supports agriculture and small settlements. The upper reaches are steeper and more forested, while the lower course broadens into flatter farmland.

Environmental concerns include water quality, habitat fragmentation, and invasive species, prompting monitoring by environmental agencies and local municipalities. The river is also valued for outdoor recreation, including fishing and boating in permitted sections, and the surrounding region attracts tourism related to nature and folklore.

Etymology and names: The river is known as Kupa in Slovenian and Croatian; in historical German-language sources it has appeared as Küpa. The name is of Slavic origin and is shared with nearby rivers in the region.