Q. Which river's tributary is the site of the Rihand Dam construction?
Answer: Sone
Notes: The Rihand Dam is a significant concrete gravity dam erected at Pipri in Uttar Pradesh's Sonbhadra District. Specifically, it is constructed on the Rihand River, a tributary of the Son River. The dam plays a dual role, marking the boundary between Chhattisgarh and Uttar Pradesh and watering the fertile plains formed by the Rihand and its tributaries in Surguja district. Eventually, it meanders into Uttar Pradesh's Sonbhadra district, making a significant contribution to the irrigation needs of both Uttar Pradesh and Bihar.