The Zarqa River is the second largest tributary of the lower Jordan River, after the Yarmouk River. It is the third largest river in the region by annual discharge and its watershed encompasses the most densely populated areas east of the Jordan River. The Zarqa rises in springs near Amman, and flows through a deep and broad valley into the Jordan, at an elevation 1,090 metres (3,580 ft) lower.

Zarqa is the capital of Zarqa Governorate in Jordan. Its name means "the blue (city)". It had a population of 635,160 inhabitants in 2015, and is the second most populous city in Jordan after Amman.