Luni
Explanation
The drainage system of the Indian Desert (Marusthali) is primarily characterized by inland drainage and ephemeral rivers due to scanty rainfall and high evaporation rates.Detailed Analysis:
- Luni is the only large and significant river in the Indian Desert region.
- Origin: It originates in the Pushkar valley of the Aravalli Range, near Ajmer. It is formed by two branches, the Saraswati and the Sabarmati, which join at Govindgarh.
- Course: It flows towards the southwest through the arid regions of Rajasthan.
- Nature: It is a seasonal (ephemeral) river. The water remains fresh in the upper reaches but turns saline further downstream near Balotra. It is also known as the Lavanavari (Salt River).
- Termination: It does not reach the open sea; instead, it drains into the marshy lands of the Rann of Kutch in Gujarat. This classifies it as a system of inland drainage.
Analysis of Other Options:
- Mahi and Sabarmati are west-flowing rivers that originate in the highlands (Vindhyas and Aravallis respectively) but flow through Gujarat to drain into the Gulf of Khambhat (Arabian Sea). They are not primarily desert rivers.
- Banas is a tributary of the Chambal river. It flows eastward and is part of the Ganga river system.
Key Takeaway: The Luni is the primary river of the arid Rajasthan region, distinct for its inland drainage into the Rann of Kutch and the salinity of its water in the lower course.