Human-Environment Interactions: The Tropical and the Subtropical Region

UPSC GS1 — Ganga Plains Geography:

The plains: The Indo-Gangetic Plain extends from Punjab in the northwest to Assam in the northeast — one of the world's most fertile and densely populated regions, formed by alluvial deposits from the Himalayan rivers.

Agricultural base:

• Green Revolution (1960s–70s): Punjab and Haryana — HYV wheat and paddy, chemical fertilisers, irrigation → transformed from deficit to surplus; India achieved food self-sufficiency
• Major crops: Wheat (Punjab, UP, Bihar, Haryana), Rice (UP, Bihar, West Bengal, Assam), Jute (West Bengal — Ganga delta), Sugarcane (UP — largest in India)
• Flood plains: Extraordinarily fertile; Ganga alluvial soil = khadar (newer, near river, very fertile) and bhangar (older, higher ground, slightly less fertile)

Major cities: Delhi, Agra, Varanasi, Allahabad (Prayagraj), Patna, Kolkata — nearly all major North Indian cities are on or near the Ganga-Yamuna system.

Brahmaputra basin:

• The Brahmaputra flows from Tibet (as the Tsangpo) through Arunachal Pradesh and Assam
• Flows through narrow valley between Himalayas and Shillong Plateau; one of the world's deepest river gorges (Yarlung Tsangpo Grand Canyon — deeper than Grand Canyon)
• Assam: Tea plantations (Assam tea = most production in India), rice, flood-prone agriculture
• Majuli Island: World's largest river island (Brahmaputra); cultural centre; facing severe erosion; area reduced from ~1,255 km² (early 20th century) to approximately 350–475 km² (estimates vary by year and methodology; Guinness records ~352 km² as of 2014; LANDSAT 2023 estimates ~474 km²)
• Brahmaputra carries enormous sediment → annual floods in Assam; over 100 rivers join it in Assam

Ganga Pollution and Action Plans:

• Ganga Action Plan (GAP) 1985: First effort to clean Ganga; largely unsuccessful
• Namami Gange Programme (2015): Rs 20,000 crore; sewage treatment, ghats, crematoria; modest improvements; NMCG (National Mission for Clean Ganga) implementing
• Main sources of pollution: Untreated sewage (major cities), industrial effluents (tanneries in Kanpur, dyeing units), agricultural runoff, solid waste, religious offerings
• Ganga declared National River of India (2008)

[Additional] Amazon Deforestation — PRODES Data, Forest Code, Tipping Point (GS3 — Environment / GS2 — International Relations):

PRODES annual deforestation data (Amazon, August–July cycle):

Key insight: Bolsonaro's 4-year term produced a ~59.5% surge in deforestation; Lula government has cut deforestation by ~50% from the 2022 baseline. However, degradation ≠ deforestation: even as clear-cutting fell, forest degradation (fire, selective logging, fragmentation) reportedly increased ~163% over 2023–2025 — degradation is NOT captured by PRODES.

Brazil's Forest Code 2012 — key provisions:

Amazon tipping point — scientific consensus:

COP30 (Belém, Brazil, November 2025):

• First COP held in the Amazon region itself
• Brazil launched Tropical Forests Forever Facility (TFFF): target USD 125 billion; pledges at launch ~USD 5.5 billion (Norway: USD 3 billion; Germany: EUR 1 billion)
• Managed by World Bank; mechanism = interest-bearing debt, not grants
• Key shortfall: COP30 ended without a binding plan to halt global deforestation — only a voluntary roadmap adopted
• Brazil's standing pledge: zero illegal deforestation by 2030 (Lula commitment, first announced COP27)

UPSC synthesis: Amazon deforestation = GS3 Environment + GS2 International Conventions. Key exam facts: PRODES = INPE's official monitoring system; 2024–25 Amazon deforestation = 5,796 km² (lowest in 11 years under Lula); Bolsonaro-era peak = 13,038 km² (2020–21); Forest Code 2012 = Legal Reserve 80% in Amazon (key fact); APP = physical geography-based protection; CAR = GIS-based registry; amnesty clause = pre-July 22 2008 deforestation on small farms = ~18 million ha exempted; tipping point = 20–25% + 1.5–1.9°C (Lovejoy/Nobre) = currently at ~17–18% deforested; TFFF = COP30 Belém November 2025 = World Bank = USD 125 billion target = USD 5.5 billion pledged at launch. Prelims trap: Deforestation (clear-cutting measured by PRODES) is DIFFERENT from forest degradation (fire, selective logging) — both threaten the Amazon but only deforestation fell significantly under Lula; PRODES measures August–July cycle (not calendar year); Legal Reserve in Amazon = 80% (NOT 60% or 70% — the 80% figure is the Amazon biome only; other biomes = 20%); tipping point threshold = 20–25% deforestation (not just 20%); current deforestation level ≈ 17–18% (approaching but not yet at the threshold); COP30 = Belém (NOT Brasília; Belém is in Pará state in the Amazon).

[Additional] India's National Waterways — NW-1, NW-2, IWAI, and Jal Marg Vikas Project (GS3 — Infrastructure / Transport):

National Waterway 1 (NW-1) — key facts:

National Waterway 2 (NW-2) — Brahmaputra:

National Waterways Act 2016:

Jal Marg Vikas Project (JMVP):

India's inland waterways cargo (latest):

Top commodities: coal, iron ore, sand, fly ash (together >68% of cargo). Top commodities moving on NW-1 include coal, fly ash, and construction materials.

IWAI — key facts:

UPSC synthesis: Inland Waterways = GS3 Infrastructure. Key exam facts: IWAI = established October 27, 1986 = HQ Noida = Ministry of Ports, Shipping and Waterways; NW-1 = Allahabad to Haldia = 1,620 km = Ganga-Bhagirathi-Hooghly = declared October 27, 1986; NW-2 = Sadiya to Dhubri = 891 km = Brahmaputra = declared September 1, 1988; National Waterways Act 2016 = 5 → 111 NWs = 20,275 km across 24 states = effective April 12, 2016; JMVP = World Bank = Varanasi to Haldia = 1,390 km = Rs 5,369 crore = WB loan USD 375 million = 3 multimodal terminals = Varanasi + Sahibganj + Haldia; FY 2024–25 cargo = 145.5 MMT (all-time record). Prelims trap: NW-1 = Allahabad (Prayagraj) to Haldia (NOT Varanasi to Haldia — JMVP covers Varanasi to Haldia which is a 1,390 km subset; NW-1 itself starts at Allahabad = 1,620 km); NW-2 = Brahmaputra (NOT Ganga; Ganga is NW-1); National Waterways Act 2016 expanded NWs from 5 to 111 (NOT from 5 to 10 or from 5 to 106 — the Act added 106 waterways, making the total 111); IWAI HQ = Noida (NOT Delhi and NOT Mumbai); World Bank loan for JMVP = USD 375 million (NOT USD 700 million — USD 700 million is the TOTAL project cost; WB loan = USD 375 million = 53% of total).