‘Bhagirathi’ and ‘Alaknanda’ rivers confluence at:

Correct — B. Devaprayag is where the Bhagirathi meets the Alaknanda, and from that confluence downstream the river is called the Ganga.

It is the last of the Panch Prayag, the five confluences along the Alaknanda in Garhwal, and the only one at which the joining stream is the Bhagirathi.

Below it the united river runs to Rishikesh and enters the plains at Haridwar, so the meeting point the question asks for is option (b).

Why the others are wrong

• (a)
  Karanprayag — At Karnaprayag the Alaknanda takes in the Pindar, not the Bhagirathi. It is one of the Panch Prayag, but the wrong one.
• (c)
  Haridwar — Haridwar is where the Ganga leaves the hills for the plains, well downstream of the meeting. No confluence of the two headstreams happens there.
• (d)
  Joshimath — Joshimath stands above the Alaknanda on the road to Badrinath. It is a town rather than a prayag, and the confluence near it is Vishnuprayag, where the Dhauliganga joins.

The Ganga has two headstreams. The Bhagirathi rises at Gaumukh, the snout of the Gangotri glacier, and the Alaknanda rises above Badrinath from the Satopanth and Bhagirath Kharak glaciers.

The Panch Prayag lie along the Alaknanda: Vishnuprayag with the Dhauliganga, Nandprayag with the Nandakini, Karnaprayag with the Pindar, Rudraprayag with the Mandakini, and Devprayag with the Bhagirathi.

The river takes the name Ganga only below Devprayag.

Key facts

• Devprayag is the confluence of the Bhagirathi and the Alaknanda, below which the river is the Ganga.
• The Bhagirathi rises at Gaumukh, the snout of the Gangotri glacier.
• The Panch Prayag are Vishnuprayag, Nandprayag, Karnaprayag, Rudraprayag and Devprayag, all on the Alaknanda.
• The tributary at Karnaprayag is the Pindar and the one at Rudraprayag is the Mandakini.

Common traps

• Taking Haridwar for the confluence because it is the famous Ganga town.
• Swapping the Pindar at Karnaprayag with the Mandakini at Rudraprayag.

No directly related past PYQ was found.