RAS question
The Luni basin covers approximately what area of Rajasthan?
Correct answer: (D) 10%.
The Luni basin covers about 10% of Rajasthan, because its catchment area of roughly 37,796 sq km is about 11% of the state's 342,239 sq km area.
Explanation
The Luni basin's catchment area is about 37,796 sq km. Compared with Rajasthan's area of about 342,239 sq km, that works out to roughly 11%, so 10% is the closest option. The Luni basin lies in the south-western part of Rajasthan, west of the Aravalli hills, and extends across parts of districts such as Ajmer, Barmer, Jalore, Jodhpur, Nagaur, Pali, Rajsamand, Sirohi and Udaipur. The river originates on the western slopes of the Aravalli range near Ajmer, drains western Rajasthan in a south-westerly direction, and disappears in the marshy land of the Rann of Kutch.
Why the other options are wrong
- (A) 20% would require a basin area far larger than about 37,796 sq km; the Luni catchment is only around 11% of Rajasthan's area.
- (B) 35% is associated with the Chambal basin, not the Luni basin; the Luni catchment is near 10% of Rajasthan's area.
- (C) 50% is much too high because a 37,796 sq km catchment is nowhere near half of Rajasthan's 342,239 sq km area.
Concept
In RAS Geography, Rajasthan drainage basins and their approximate spatial extent matter because basin size, regional drainage and desert hydrology often connect with map-based analysis.