Which one of the following rivers is NOT the part of Indian Ganga river basin?

Question

UnlockIAS · Accepted Answer

Correct — D, Jonk river. The Jonk is a tributary of the MAHANADI, rising on the Chhattisgarh-Odisha uplands and joining the Mahanadi system — so it drains the Mahanadi basin, NOT the Ganga basin. The other three all belong to the Ganga system: Punpun (Bihar), Ajoy/Ajay (Jharkhand-West Bengal) and Jalangi (West Bengal) each end up in the Ganga/Bhagirathi-Hooghly network. Since the question asks which river is NOT part of the Ganga basin, the Mahanadi tributary Jonk (d) is the answer.

Why the other options are wrong — (a) Belongs to the Ganga basin (so not the answer) — the Punpun rises in the Chotanagpur plateau and flows through Bihar to join the Ganga a little downstream of Patna.  (b) Belongs to the Ganga basin (so not the answer) — the Ajay (Ajoy) rises in Jharkhand, flows through West Bengal and joins the Bhagirathi-Hooghly, the deltaic distributary of the Ganga.  (c) Belongs to the Ganga basin (so not the answer) — the Jalangi is a river of Nadia district, West Bengal, that carries Ganga water and joins the Bhagirathi (Hooghly), part of the Ganga delta network.

Concept: A river basin is the total area drained by a river and all its tributaries. Three of these rivers feed the Ganga system — the Punpun joins the Ganga trunk in Bihar, while the Ajay and Jalangi feed the Bhagirathi-Hooghly in the Ganga delta of West Bengal. The Jonk is different: it is a tributary of the Mahanadi, which is an independent east-flowing peninsular river that empties into the Bay of Bengal near Paradip, entirely separate from the Ganga system.

State PCS 2021 Q89 — Geography PYQ with Answer

State PCS 2021 Q89 — Geography PYQ with Answer