The West Rapti, also known as the Kuwano, is a river which drains Rapti Zone in Mid-Western Region, Nepal, then Awadh and Bhojpur-Purvanchal regions of Uttar Pradesh state, India before joining the Ghaghara. It is a major left bank tributary of the Ganges, and is also known as the Karnali in Nepal.
The West Rapti is notable for janajati ethnic groups – Kham Magar among its highland sources and then Tharu in Inner Terai Deukhuri Valley, for its irrigation and hydroelectric potential, and for recurrent floods that led to its nickname "Gorakhpur's Sorrow".