Geography of Rajasthan: Comprehensive Analysis

1. Physical Divisions of Rajasthan

Rajasthan is the largest state in India (3,42,239 sq km). It is divided into four major physical units:

A. Western Sandy Plains (Thar Desert)

• Coverage: 61.11% of the total area. Holds 40% of the population.
• Sub-divisions: Marusthali (Sand dunes) and Semi-arid transition zone (Bangur).
• Key Features: Luni Basin, Shekhawati Region, and Ghaggar Plain.
• Lathi Series: A geological formation in Jaisalmer known for its groundwater and Sevan grass.

B. Aravalli Range and Hilly Region

• Age: One of the oldest fold mountain ranges in the world (Pre-Cambrian era).
• Extent: 692 km total (550 km in Rajasthan) from Khetri to Sirohi.
• Highest Peak: Guru Shikhar (1722 m) in Mount Abu.
• Importance: Acts as a water divide and prevents the eastward expansion of the desert.

C. Eastern Plains

• Coverage: 23% of the area. Formed by alluvial deposits of Banas, Chakal, and Mahi rivers.
• Sub-divisions: Chappan Plain (Pratapgarh-Banswara), Banas-Banganga Basin.

D. South-Eastern Plateau (Hadoti Plateau)

• Coverage: 6.89% of the area. Volcanic (Lava) origin.
• Regions: Mukundara hills and Vindhyan scarpland.

2. Drainage System: Rivers and Lakes

Rajasthan's drainage is classified into three types based on the target water body:

A. Inland Drainage (60%)

• Rivers that disappear in the sand without reaching the sea.
• Rivers: Ghaggar (Dead River), Katli, Sabi, Kakni.

B. Arabian Sea Drainage (17%)

• Rivers: Luni (Salt River), Mahi (Crosses Tropic of Cancer twice), Sabarmati, West Banas.

C. Bay of Bengal Drainage (23%)

• Rivers: Chambal (Perennial, known for badland topography), Banas (Hope of Forest), Banganga, Berach.

3. Climate and Soils

• Climate Types (Koppen's Classification):
  • BWhw: Arid (Western desert).
  • BShw: Semi-arid.
  • Cwg: Steppe type (Eastern plains).
  • Aw: Tropical Humid (Southern part).
• Soils:
  • Aridisols: Found in western dry regions.
  • Alfisoils: Fertile alluvial soil in the east.
  • Vertisoils: Black soil in Hadoti (Cotton growing).

4. Mineral Wealth: The "Museum of Minerals"

Rajasthan produces 81 types of minerals (57 metallic/non-metallic and 24 minor).

• Monopoly (100%): Wollastonite, Jasper, Zinc, Lead.
• Key Mines:
  • Lead-Zinc: Zawar (Udaipur), Rampura-Agucha (Bhilwara).
  • Copper: Khetri (Jhunjhunu).
  • Gypsum: Jamsar (Bikaner).
  • Rock Phosphate: Jhamar Kotra (Udaipur).
  • Marble: Makrana (Nagaur) - used in Taj Mahal.