Q. Northern Koel is a tributary of which river?
Answer: Sone
Notes: The Northern Koel River is the second largest right bank tributary of the Sone River. It originates in the Ranchi Plateau, Jharkhand, and flows through Latehar and Palamu districts before joining the Sone near Haidargarh. The North Koel Reservoir Project includes a dam near Kutku and benefits irrigation in Jharkhand and Bihar. It is distinct from the Damodar, Swarna Rekha, and Barakar rivers.