West Rapti

The West Rapti gathers in the Mahabharat hills of Rolpa and Pyuthan, where its headwaters — the Jhimruk, Madi and Lungri kholas — drain ridges rising to about 3,500 m. The combined river winds down through the broad inner-Tarai valleys of Dang and Deukhuri, slips through the Churia hills past Banke, and crosses into India's Uttar Pradesh, joining the Ghaghara roughly 60 km beyond Gorakhpur. It is distinct from the East Rapti, which flows through Chitwan into the Narayani.

It is a rain-fed river of extremes. The long-term average flow near its mouth is about 136 m³/s, but August alone averages around 451 m³/s, and the record flood of 10 September 1981 reached 7,390 m³/s. Those floods have earned it the name 'Gorakhpur's Sorrow' across the border, where hundreds of thousands of hectares lie in its flood zone — and flood early-warning between Nepali and Indian communities on the Rapti has become a model for other border rivers.

In the Nepali hills the river earned a different distinction: the 12 MW Jhimruk plant in Pyuthan, commissioned in 1994 by Butwal Power Company, was a pioneering domestically built private hydropower project. It drops Jhimruk water 205 m into the neighbouring Madi valley and has become an international case study in operating turbines in the Himalaya's abrasive, sediment-heavy monsoon rivers. Downstream, the West Rapti irrigates the Dang and Banke plains — one of Nepal's main grain belts.