RAS question
Hirakud Dam is known as one of the longest dams in the world. What is its approximate total length including dykes?
Correct answer: (B) About 25.8 km.
Hirakud Dam, including its dykes, is approximately 25.8 km long.
Explanation
Hirakud Dam is counted among the world's longest dams because the figure refers to the whole dam system, not only the central masonry-and-earth structure. The main dam is about 4.8 km long, while the earthen dykes on both sides add about 21 km, making the total length about 25.8 km. The dam stands across the Mahanadi River near Sambalpur in Odisha. It opened in 1957 and is described as one of India's first major multipurpose river valley projects after Independence. Therefore, for an RAS question asking for the approximate total length including dykes, the defensible answer is about 25.8 km, not the shorter length of the main dam alone.
Why the other options are wrong
- (A) About 50 km overstates the total length; the dam and dykes together are about 25.8 km, roughly half that figure.
- (C) About 10 km is too short because it misses most of the dyke length added to the 4.8 km main dam.
- (D) About 5 km is close only to the main dam length, not to the full length including dykes.
Concept
This tests Indian geography through major river-valley projects, where examiners often ask exact physical features of landmark dams. It recurs in RAS because dams link drainage, irrigation, hydropower and regional development in one factual cluster.