Karnali

The Karnali rises on the Tibetan plateau near Lake Manasarovar and Mount Kailash — its headwater glacier, the Mapchachungo, feeds it from about 3,962 m — and enters Nepal in Humla as the Humla Karnali. Gathering the Mugu Karnali and the Tila, it runs the whole length of western Nepal through some of the country's remotest gorges: at ≈507 km in-country it is Nepal's longest river, and 1,080 km from source to the Ganga.

At Chisapani the river bursts out of its last gorge onto the Tarai beside Bardiya National Park, splitting into branches across the plain before crossing into India, where it becomes the Ghaghara (and, lower down, the storied Sarayu of Ayodhya). The full basin is vast — 127,950 km² — and the river carries a mean flow of about 1,369 m³/s through its Nepal reach, swelling to roughly 2,990 m³/s by the time the Ghaghara meets the Ganga.

The Karnali is Nepal's last big free-flowing river, and that wildness shows in what lives on it: the Bardiya stretch supports gharial crocodiles and what is considered the last potentially viable population of the Ganges river dolphin in Nepal, while the river corridor links tiger and elephant habitat in Bardiya's 968 km² of jungle. It is also the country's premier multi-day wilderness rafting river.

Its undammed state may not last. The 900 MW Upper Karnali — licensed to India's GMR group, designed as a run-of-river plant with eight 112.5 MW turbines — has restarted after nearly two decades of delay, and the lower gorge at Chisapani is the site of the long-studied Karnali-Chisapani multipurpose project, which on paper could exceed 10,000 MW. The tension between that potential and the river's free-flowing ecology defines the Karnali debate.