The river in question is Arun that starts from Tibet as Phung Chu and is one of the seven rivers that forms Kosi river ...

The Kosi river's water discharge at Veerpur Barrage was recorded at 1,08,600 cusecs at 2 pm on Thursday (July 04), while the Gandak river's discharge at Valmikinagar barrage was 88,300 cusecs at 2 pm.