Key Points at a Glance

These key points summarise the core physiography, river-system and lake facts an RAS aspirant should be able to recall quickly.

1. Rajasthan covers 3,42,239 sq km (10.41% of India's land area), making it the largest Indian state by area.
2. The four physiographic divisions are the Western Sandy Plain (61.11%), Aravalli Range (9.3%), Eastern Plains (23.0%) and South-Eastern Plateau or Hadoti (6.6%).
3. The Aravalli Range is among the world's oldest fold-mountain systems, formed in the Pre-Cambrian era, about 2,500 million years ago. It extends about 692 km within Rajasthan, and its highest point is Guru Shikhar (1,722 m) at Mount Abu in Sirohi.
4. The Thar Desert covers about 61% of Rajasthan's area. Average annual rainfall in the core desert is below 25 cm, and sand dunes, locally called dhores, are its most characteristic landform.
5. Luni is the longest river of western Rajasthan, about 495 km long. It originates near Pushkar in Ajmer district, flows towards the Rann of Kutch, and is called the "Salt River" because its water turns brackish below Balotra.
6. Chambal is the largest river flowing through Rajasthan in the Yamuna system. India-WRIS records it as a 960 km tributary of the Yamuna, and it is the major perennial river associated with ravine badlands in the Kota-Sawai Madhopur-Dholpur belt.
7. Banas is the major river flowing entirely within Rajasthan in the standard RPSC/RBSE convention. It originates in the Khamnor hills of Rajsamand and joins the Chambal at Rameshwar Ghat in Sawai Madhopur.
8. Inland drainage covers roughly 60% of Rajasthan. Rivers such as Ghaggar, Kakni or Machhad, Kantli and the dry Saraswati lose water to sand, playas or evaporation before reaching the sea.
9. Sambhar Lake is India's largest inland saltwater lake. It covers about 240 sq km or 24,000 ha, is a Ramsar site, produces roughly 2-2.5 lakh tonnes of salt annually, and lies around the Jaipur-Nagaur-Ajmer tri-junction.
10. Jaisamand Lake, also called Dhebar Lake, is historically cited as Asia's second-largest artificial lake. Maharana Jai Singh built it in 1685-91 by damming the Gomati River, and its surface area is about 87 sq km in Udaipur district.
11. Indira Gandhi Nahar Pariyojana (IGNP), earlier called the Rajasthan Canal, has a 649 km main canal from Harike Barrage in Punjab towards the western desert. Stage I is 204 km and Stage II is 445 km.
12. Chambal Valley Development Project has three major dams: Gandhi Sagar in Madhya Pradesh, Rana Pratap Sagar at Rawatbhata in Chittorgarh, and Jawahar Sagar near the Kota-Bundi border. Their combined installed hydropower capacity is about 386 MW.
13. The Aravalli Range is Rajasthan's main watershed divide. Rivers west of it drain towards the Arabian Sea or into inland basins, while rivers east of it drain towards the Bay of Bengal through the Chambal-Yamuna-Ganga system.
14. Pushkar Lake in Ajmer district is the major lake associated with Brahma worship and has a distinctive sacred-geography role in Rajasthan's lake system.
15. Nakki Lake at Mount Abu is Rajasthan's highest major lake, at about 1,200 m elevation, and is linked in local tradition to a lake scooped out with fingernails.