RAS question
Hirakud Dam is built on which river?
Correct answer: (D) Mahanadi.
Hirakud Dam is built on the Mahanadi river in Odisha.
Explanation
Hirakud Dam is correctly matched with the Mahanadi. The India WRIS page on dams in Odisha lists Hirakud Dam at Sambalpur, with the river column showing Mahanadi and the basin column also showing Mahanadi. This is why option D is the answer. The exam-relevant memory hooks are clear: Hirakud is in Odisha, it is one of the world's longest earthen dams at 25.8 km, and the Mahanadi originates from Sihawa in Chhattisgarh. For RAS-style geography questions, the safest association is therefore Hirakud-Mahanadi-Odisha, not just the dam name in isolation.
Why the other options are wrong
- (A) Godavari is not the river for Hirakud Dam; Sriram Sagar and Polavaram are Godavari dam associations, while WRIS lists Hirakud against Mahanadi.
- (B) Krishna is a wrong match because Nagarjuna Sagar and Srisailam are Krishna dam associations, whereas Hirakud is listed on the Mahanadi.
- (C) Narmada is ruled out because its major dam associations are Sardar Sarovar and Indira Sagar, not Hirakud.
Concept
This tests the standard Indian geography mapping of major dams to rivers and states. It recurs in RAS because river-valley projects connect physical geography, irrigation, hydropower and regional development in a compact factual frame.