Vrbas (river)

The Vrbas is a major river with a length of 235 kilometres (146 mi), in western Bosnia and Herzegovina. It is a right tributary of the Sava river. The city of Banja Luka is located on the river banks. 

The word vrba means "willow" in Bosnian, Serbian and Croatian, and a number of weeping willow trees adorn the river banks in Banja Luka.

It lent its name to one of the provinces (banovinas) of the Kingdom of Yugoslavia, the Vrbas Banovina.

It is a right tributary of the river Sava. The Vrbas river appears at the southern slope of the Vranica mountain near the town of Gornji Vakuf, at around 1,530 metres (5,020 ft) above sea level and it drains central part of the northern slopes of the Dinaric mountain massif. It empties into the Sava river at around 90 metres (300 ft) above sea level. Total length of the main watercourse is around 235 kilometres (146 mi).

Average annual rainfall is around 800 l/m2 at the mouth of the Vrbas to the Sava river and up to 1500 l/m2 in the southern part of the basin. Characteristic mean flow is around 34,6 l/s/km2 Maximum rainfall occurs in the southern parts of the Vrbas basin in the late autumn and winter months, with minimum quantities in summer, whereas the northern parts of the basin receive the largest quantities of rain during the summer months (June–July), with the maximum in November and December.

The most important right tributaries are the Desna river, the Ugar, and the Vrbanja, and left: Prusačka river, Semešnica, the Pliva, the Crna Rijeka (Black River), and the Suturlija, which are located in the middle part of the basin