India's Drainage Systems and Mineral Resources

India's rivers and its mineral deposits sit on the same geological base. Most metallic minerals occur in the old crystalline rocks of the peninsular plateau, and the rivers draining off that same plateau, alongside the Himalayan rivers, have been dammed for decades to store and distribute water. UPSC draws heavily on both the Water Resources and the Mineral and Energy Resources chapters, and it tests named rivers, named dams and named mining belts, not general definitions.

India's River Basins

India gets about 4,000 cubic km of water a year from precipitation. Of the 1,869 cubic km available from surface flow and replenishable groundwater, only about 60 per cent, roughly 1,122 cubic km, can actually be put to beneficial use once topography and other constraints are accounted for. There are over 10,360 rivers and tributaries longer than 1.6 km in the country.

A single fact worth remembering precisely: the Ganga, Brahmaputra and Barak basins together account for only about one-third of India's total area, but because their catchments sit in the highest-rainfall zones, they hold 60 per cent of the country's total surface water resources. Much of south India's river flow, by contrast, in the Godavari, Krishna and Kaveri, has already been harnessed, while the Brahmaputra and Ganga basins still have large untapped potential.

NCERT's river-basins map splits the country into west-flowing and east-flowing systems. The Indus, Ganga, Brahmaputra and Barak basins, along with the Narmada and Tapi, are grouped on the west-flowing and northern-plains side; the Mahanadi, Godavari, Krishna, Pennar and Kaveri flow east into the Bay of Bengal. Two further groups get their own label: the small west-flowing rivers of Kachchh, Saurashtra and the Luni, and the west-flowing rivers south of the Tapi.

Multipurpose Projects and Water Demand

India's water demand is dominated by irrigation: agriculture accounts for 89 per cent of surface water use and 92 per cent of groundwater use, against just 2 per cent and 5 per cent for industry. To meet this, the Five Year Plans took up a set of multipurpose river valley projects that UPSC names directly: Bhakra-Nangal (Sutlej), Hirakud (Mahanadi), the Damodar Valley project (Damodar), Nagarjuna Sagar (Krishna), and the Indira Gandhi Canal Project. Punjab, Haryana and western Uttar Pradesh owe the Green Revolution's success largely to assured irrigation from projects and wells built on this base.

Where the Water Stress Actually Shows Up

Heavy reliance on wells and tubewells, 76.1 per cent of Punjab's net irrigated area and 51.3 per cent of Haryana's, has driven a real decline in the water table in both states. Over-extraction has a second, less obvious cost: it has raised fluoride concentration in groundwater in Rajasthan and Maharashtra, and raised arsenic concentration in parts of West Bengal and Bihar. On surface water, the Central Pollution Control Board's monitoring identifies the Yamuna between Delhi and Etawah as the most polluted river stretch in the country, ahead of the Sabarmati, the Gomti and the Ganga at Kanpur and Varanasi.

The Three Mineral Belts

NCERT groups most of peninsular India's minerals into three broad belts, with a separate Himalayan belt alongside them.

• North-Eastern Plateau belt: Chhotanagpur (Jharkhand), the Odisha plateau, West Bengal and parts of Chhattisgarh. Iron ore, coal, manganese, bauxite and mica all occur together here, which is exactly why India's iron and steel industry clustered in this belt.
• South-Western Plateau belt: Karnataka, Goa, and the Tamil Nadu and Kerala uplands. Rich in ferrous metals and bauxite, but it lacks coal deposits except for Neyveli lignite. Kerala has monazite, thorium and bauxite clay; Goa has iron ore.
• North-Western belt: along the Aravalis in Rajasthan and part of Gujarat, tied to the Dharwar rock system. Copper and zinc are the major minerals; Rajasthan also supplies building stone (sandstone, granite, marble), gypsum and Fuller's earth, while Gujarat has petroleum and salt.
• A separate Himalayan belt carries copper, lead, zinc, cobalt and tungsten on both its eastern and western flanks. Offshore, petroleum comes from Mumbai High and the sedimentary basins of Assam and Gujarat, with newer reserves found in the Krishna-Godavari and Kaveri basins.

Named Deposits Worth Remembering

• Iron ore: over 95 per cent of reserves sit in Odisha, Jharkhand, Chhattisgarh, Karnataka, Goa, Telangana, Andhra Pradesh and Tamil Nadu. Named mines: Gurumahisani, Sulaipet, Badampahar and Bonai in Odisha; Noamundi and Gua in Jharkhand; Bailadila and Dalli-Rajhara in Chhattisgarh; Ballari and Kudremukh in Karnataka.
• Manganese: Madhya Pradesh's Balaghat-Chhindwara-Nimar-Mandla-Jhabua belt, and Karnataka (Dharwar, Ballari, Chikkamagaluru).
• Bauxite: Odisha is the largest producer, led by Kalahandi and Sambalpur.
• Copper: Singhbhum (Jharkhand), Balaghat (Madhya Pradesh), and Jhunjhunu and Alwar (Rajasthan).
• Mica: Jharkhand's belt in the lower Hazaribagh plateau supplies the bulk of production; Andhra Pradesh's Nellore district produces the best quality; Rajasthan's belt runs about 320 km from Jaipur to Bhilwara and around Udaipur.

The Exam Trap: Major versus Minor Minerals

This distinction is a UPSC favourite precisely because it is a legal category, not a geological one. Under Section 3(e) of the Mines and Minerals (Development and Regulation) Act, 1957, "minor minerals" are defined by name: building stones, gravel, ordinary clay and ordinary sand (other than sand used for prescribed purposes), plus anything else the Central Government chooses to notify as a minor mineral. Everything else, including big-ticket minerals like iron ore, bauxite, manganese, coal and petroleum, counts as a major mineral by default. The Act never defines "major mineral" on its own terms.

The consequence UPSC tests: minor minerals are regulated by State Governments (rules, royalty rates, leases, under Section 15 of the Act), while major minerals fall under the Union Government through the Ministry of Mines. A mineral's economic value has nothing to do with which list it sits on. It is purely a question of what Parliament, or a Central Government notification, has named.

Quick revision points

• Ganga + Brahmaputra + Barak basins: about one-third of India's area, 60 per cent of its surface water.
• Multipurpose projects to know by river: Bhakra-Nangal (Sutlej), Hirakud (Mahanadi), Damodar Valley (Damodar), Nagarjuna Sagar (Krishna), Indira Gandhi Canal.
• Agriculture uses 89 per cent of surface water and 92 per cent of groundwater in India; the Yamuna (Delhi to Etawah) is the country's most polluted river stretch.
• Three mineral belts: North-Eastern Plateau (iron, coal, manganese, bauxite, mica together), South-Western Plateau (ferrous metals and bauxite, almost no coal), North-Western (copper, zinc, building stone, along the Aravalis).
• Odisha leads bauxite and iron ore reserves; Madhya Pradesh and Karnataka lead manganese; Jharkhand's Singhbhum leads copper.
• Minor minerals (building stones, gravel, ordinary clay, ordinary sand, plus anything Centre-notified) are regulated by the States; every other mineral is a major mineral, regulated by the Union.

Once the river basins, the named dams and the mineral belts are fixed in place, practise the statement-based and matching-pairs questions UPSC builds around them.