Correct Option
The correct option is (a).
Explanation
The Indian Desert, also known as the Thar Desert, is a distinct physiographic division located in the northwest part of India. It is characterized by an undulating sandy plain covered with various types of sand dunes and possesses an arid climate.
Statement-wise Analysis:
- Statement 1 is Correct: The Great Indian Desert is situated towards the western margins of the Aravali Hills. Geologically, it is an extension of the Peninsular plateau but has distinct surface features due to intense aeolian (wind) activity.
- Statement 2 is Correct: The region experiences an extremely arid climate. It receives very low rainfall, typically below 150 mm per year. This low precipitation, combined with high evaporation, results in low vegetation cover and water scarcity.
- Statement 3 is Correct: The drainage system in the desert is ephemeral. Streams appear only during the rainy season and often disappear into the sand before reaching the sea (inland drainage). Luni is the only large and significant river in this region.
- Statement 4 is Incorrect: Barchans are crescent-shaped dunes, not longitudinal dunes. While Barchans do cover significant areas, longitudinal dunes (seifs) are distinct linear structures that become more prominent near the Indo-Pakistan boundary.
Key Takeaway:
The Indian Desert is an arid zone west of the Aravalis characterized by low rainfall (<150 mm), ephemeral drainage (Luni river), and specific dune forms like crescent-shaped Barchans and linear longitudinal dunes.