Originating from Vasudhara Tal, perhaps the largest glacial lake in Uttarakhand, the Dhauliganga flows in a meandering course, which takes it through the Nanda Devi National Park.
Known for its spectacularly beautiful route and whitewater rafting, the river turned into a deathly torrent on Sunday after a part of the Nanda Devi glacier broke off and collapsed into it.
The Dhauliganga, which merges with the Alaknanda, is one of the several tributaries of the Ganga, as the river flows down from the Himalayas and snakes its way through the plains. The tributaries intersect, flow into one another or meander away passing through several towns in five States.
In Uttarakhand, the Ganga and its tributaries pass through important tourist places such as Rishikesh, Haridwar, Rudraprayag and Karnaprayag. Sunday’s collapse of the glacier led to rippling flash floods in the Dhauliganga and the Rishiganga and also impacted the Alaknanda.
This also brought spotlight on the 2013 flash floods in the hill States that wiped out settlements and killed over 5,000 people.
Dhauliganga is joined by Rishiganga river at Raini where the disaster at the power project dam took place.
The river takes a V-turn and continues to flow in the opposite direction, toward north, as the Dhauliganga for another 30-odd km, through Tapovan, until it is joined by the Alaknanda at Vishnuprayag near Joshimath.
There it loses its identity and the Alaknanda flows southwest — through Chamoli, Maithana, Nandaprayag, Karnaprayag until it meets the Mandakini river, coming from the north at Rudraprayag.
After subsuming Mandakini, the Alaknanda carries on past Srinagar, before joining the Ganga at Devprayag near Kedarnath.
Alaknanda then disappears and the mighty Ganga carries on its journey, first flowing south then west through important pilgrimage centres such as Rishikesh and finally descending into the Indo-Gangetic plains at Haridwar.
Still on a southern course, the Ganga goes past Bijnor when it loops back on an easterly course toward Kanpur.
The Yamuna, Ramganga and Ghaghara are the other Himalayan rivers that join the Ganga.
Dhauliganga is one of the important tributaries of Alaknanda, the other being the Nandakini, Pindar, Mandakini and Bhagirathi.
The Himalayan rivers pass through environmentally fragile areas. However, like other Himalayan rivers, the Dhauliganga too has been dammed. Dhauliganga also has a power station of the National Hydropower Corporation Ltd of 280 MW at Pithoragarh in Uttarakhand.
According to the South Asia Network on Dams, Rivers and People, a think tank, under construction HEPs threaten about 50% of the Dhauliganga’s length.