CDS (I) 2020 General Knowledge · Question 41 of 120

Correct — B, Son. The Son rises on the Amarkantak plateau, close to the source of the Narmada, and runs north-east across Madhya Pradesh, Jharkhand and Bihar to meet the Ganga a little upstream of Patna, near Maner. It is the Ganga's largest southern tributary and the only one of the four named rivers that reaches the Ganga at all. The other three are second-order rivers of the same peninsular block: Chambal, Betwa and Ken all flow north into the Yamuna, and their water reaches the Ganga only when the Yamuna itself joins it at Prayagraj. Amarkantak is worth fixing in memory because two great rivers part there — the Son turning north-east for the Bay of Bengal by way of the Ganga, the Narmada running west to the Arabian Sea.

• (a)Chambal — Rises in the Vindhyas near Mhow and flows north-east into the Yamuna near Etawah in Uttar Pradesh. Its own tributaries are the Banas, Kali Sindh and Parbati; it never touches the Ganga.
• (c)Betwa — Rises in the Raisen district of Madhya Pradesh and joins the Yamuna at Hamirpur. It is the Yamuna's, not the Ganga's.
• (d)Ken — Runs north from the Panna hills through the Bundelkhand country and joins the Yamuna near Chilla in Banda district. It is the river at the Ken-Betwa link project, which moves water between two Yamuna tributaries.

The Ganga's right-bank feeders come off the peninsular block and are seasonal, while its left-bank feeders come off the Himalaya and run all year. Of the southern rivers, the Son is the largest to join the main stream directly; the Chambal, Betwa, Ken and Sind all feed the Yamuna instead, and the Yamuna carries their water into the Ganga at the confluence at Prayagraj.

The item is a one-step test of the drainage hierarchy, and the fastest route to it is to remember which peninsular rivers are Yamuna tributaries. Chambal, Sind, Betwa and Ken form a tidy set — all Bundelkhand and Malwa rivers flowing north into the Yamuna — and the odd one out is the Son. It helps that the Son's identity is anchored elsewhere too: Amarkantak as its source, shared with the Narmada, and Rohtas and Dehri on its lower course. The paper spells the confluence question simply, but note that many textbooks describe the Son as joining the Ganga near Patna rather than naming Maner.

• The Son rises on the Amarkantak plateau and joins the Ganga upstream of Patna, near Maner.
• Amarkantak is the common source of the Son, which flows north-east to the Ganga, and the Narmada, which flows west to the Arabian Sea.
• The Chambal, Sind, Betwa and Ken are all tributaries of the Yamuna, not of the Ganga.
• The Son is the largest of the Ganga's peninsular, right-bank tributaries.
• The Ken-Betwa link project transfers water between two Yamuna tributaries in the Bundelkhand region.

• Assuming any large north-flowing peninsular river must reach the Ganga; most reach the Yamuna first.
• Confusing the Son with the Sind, which is a Yamuna tributary in Madhya Pradesh.

As a tributary-to-river match, a which-one-joins-directly item, or a source-region identification.

• practice — not a real PYQ

  The Chambal, Sind, Betwa and Ken are all tributaries of which one of the following rivers?

  • (a)Ganga
  • (b)Yamuna
  • (c)Narmada
  • (d)Mahanadi

  Answer(b) Yamuna — all four flow north from the Malwa and Bundelkhand uplands into the Yamuna, which then carries their water to the Ganga.

• practice — not a real PYQ

  The Narmada and the Son both rise in which one of the following areas?

  • (a)Mahabaleshwar
  • (b)Amarkantak
  • (c)Brahmagiri
  • (d)Sahyadri near Nashik

  Answer(b) Amarkantak — the Narmada flows west to the Arabian Sea from there, while the Son flows north-east to join the Ganga.