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GS Paper: GS1-15.Geographical features and their location- Changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.

  • Wind Stilling Effect in the Indo-Gangetic Plain (IGP)

    Why in the News?

    A satellite-based study (2003–2020) of 141 Indian cities revealed a surprising aerosol pattern — southern cities act as pollution hotspots, while many northern cities form ‘clean islands’ due to a phenomenon called the Wind Stilling Effect.

    Key Highlights of the Study:

    • Conducted by: The Indian Institute of Technology Bhubaneswar.
    • Method: Used high-resolution aerosol optical depth data to track pollution.
    • Focus: Examined how urbanisation interacts with natural and transported pollution.
    • Surprising Insight: Many northern cities were not major aerosol hotspots, contrary to assumptions.
    • Classification of Cities: Two categories based on aerosol levels relative to surrounding areas:
      • Urban Aerosol Pollution Islands-
        • Location: Predominantly in southern and southeastern India.
        • Characteristics: Cities had higher aerosol levels than nearby rural surroundings.
        • Pollution Source: Mostly local emissions from vehicles, construction, and industries.
        • Absence of External Influence: Minimal contribution from long-range dust or biomass burning.
      • Urban Aerosol Clean Islands-
        • Location: Observed in northwestern India and the Indo-Gangetic Plain.
        • Pattern: Cities had lower aerosol levels than nearby upwind (southwest) areas.
        • Mechanism: Incoming pollutants were blocked or deflected, creating a “clean island” effect.
        • Downwind Evidence: Northeast (downwind) sides showed equal or lower aerosol levels compared to city centres.

    About the Wind Stilling Effect:

    • Overview: A phenomenon where dense urban infrastructure reduces surface wind speed, altering local airflow.
    • Barrier Formation: Slowed winds create atmospheric stagnation zones, especially on the upwind side.
    • Pollution Blocking: Long-range pollutants like Thar Desert dust or biomass smoke are slowed or blocked.
    • Misleading Cleanliness: Cities appear cleaner not due to lower emissions, but due to pollution deflection.
    • Seasonality: Most evident during the pre-monsoon season, when dust transport is high and cloud cover is minimal.
    [UPSC 2010] If there were no Himalayan ranges, what would have been the most likely geographical impact on India ?

    1. Much of the country would experience the cold waves from Siberia. 2. Indo-gangetic plain would be devoid of such extensive alluvial soils. 3. The pattern of monsoon would be different from what it is at present.

    Which of the statements given above is/are correct ?

    Options: (a) 1 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3*

     

  • [22nd July 2025] The Hindu Op-ed: Water, energy demand spotlights risk of human-induced quakes 

    PYQ Relevance:

    [UPSC 2020] Discuss the geophysical characteristics of Circum-Pacific Zone.

    Linakge: This question is about a region known for earthquakes and volcanoes. The article mainly talks about quakes caused by human activity but also mentions that these usually happen in places already on fault lines or where tectonic plates are shifting—areas like the Circum-Pacific. So, it’s important to understand these natural zones when looking at how human actions might trigger earthquakes.

     

    Mentor’s Comment:  Human-induced earthquakes are increasingly drawing scientific and public attention, as research shows that human activities like groundwater extraction, dam construction, and fracking can trigger or accelerate seismic activity, particularly in tectonically sensitive regions such as Delhi-NCR, the Western Ghats, and parts of Maharashtra and Kerala.

    Today’s editorial analyses the Issues related to Human-induced earthquakes in India. This topic is important for GS Paper I (Geography), GS Paper II (Governance) and  GS Paper III (Disaster Management) in the UPSC mains exam.

    _

    Let’s learn!

    Why in the News?

    Recent studies in India have highlighted a correlation between excessive groundwater depletion and increased seismic events, especially in Delhi.

    What are human-induced earthquakes?

    • These are earthquakes triggered by human activities rather than natural tectonic movements. Activities like mining, groundwater extraction, building dams, and fracking disturb the earth’s crust, causing seismic activity. Over 700 human-induced quakes have been recorded globally in the last 150 years.

     

    How do activities like groundwater extraction and dams trigger quakes in India?

    • Groundwater Depletion Weakens Crustal Stability: Excessive extraction of groundwater reduces pore pressure, leading to a shift in stress within the earth’s crust. Eg: In Delhi-NCR, increased seismic activity between 2003–2012 has been linked to excessive groundwater loss.
    • Reservoir-Induced Seismicity (RIS): The weight of large reservoirs exerts additional pressure on underlying faults, triggering quakes. Eg: The 1967 Koynanagar earthquake (magnitude 6.3) was linked to the Koyna Dam in Maharashtra.
    • Water Infiltration into Fault Zones: Water from reservoirs or excessive irrigation can seep deep into fault lines, lubricating them, and making them more likely to slip. Eg: Seismic tremors near Mullaperiyar Dam in Kerala are suspected to be induced due to water infiltration in a seismically sensitive region.
    • Load Variation Due to Filling and Emptying of Dams: Rapid filling or draining of reservoirs changes the stress distribution, causing small or moderate tremors. Eg: In the Himalayan region, such stress changes are a concern for dams like Tehri Dam.
    • Ground Subsidence from Overuse of Aquifers: Excessive groundwater extraction leads to land subsidence, altering the natural equilibrium of stress in the crust. Eg: Regions in North Gujarat have experienced subsidence, making them more vulnerable to fault reactivation and quakes.

    Why is Delhi-NCR prone to quakes from groundwater loss?

    • Rapid Groundwater Depletion Alters Stress Fields: Excessive groundwater extraction reduces the hydrostatic pressure underground, disturbing the natural stress balance in fault zones. This stress redistribution can reactivate dormant faults, triggering seismic activity. Eg: Studies from 2003–2012 show increased microseismic activity in parts of Gurgaon and Faridabad, correlated with falling water tables.
    • Aquifer-Related Land Subsidence: Continuous overuse of aquifers causes the land to sink (subsidence), which can strain the Earth’s crust and disturb nearby fault lines. In Delhi-NCR, land sinking has been recorded in Dwarka, Kapashera, and parts of Noida, increasing quake risk. Eg: A 2021 study by IIT-Kanpur showed that excessive aquifer use led to ground subsidence and elevated seismic hazard.
    • Built-Up Pressure on Seismically Active Faults: Delhi-NCR sits near the Mahendragarh-Dehradun fault and Delhi-Haridwar ridge, making it naturally earthquake-prone. When groundwater is extracted, it weakens the structural resistance of rocks, making nearby active faults more vulnerable. Eg: Minor tremors in Rohini and West Delhi (2020-21) were suspected to be linked to combined stress from tectonics and human activity.

    How does climate change contribute to seismic risks?

    • Melting Glaciers Increase Uplift Pressure: Rapid glacial melt in the Himalayas (due to rising temperatures) reduces surface weight. This triggers isostatic rebound — the crust rises and shifts, which can activate faults beneath. Eg: In Uttarkashi (Uttarakhand), increased seismic activity has been observed near retreating Gangotri Glacier, linked to glacial thinning and uplift.
    • Changing Rainfall Patterns Cause Landslides and Crustal Stress: Intense rainfall and flash floods (exacerbated by climate change) cause rapid groundwater recharge and erosion, disturbing fault stability. Eg: In Kodagu (Karnataka), unusually heavy rains in 2018 triggered landslides and minor tremors due to destabilized slopes and crustal shifts.
    • Sea-Level Rise and Coastal Seismic Pressure: Rising sea levels increase water load on coastal plates, especially in delta regions. This can suppress or activate tectonic stresses near coastlines. Eg: In Sundarbans (West Bengal), changes in sediment load and sea-level rise have raised concerns of future seismic risks in this low-lying, tectonically sensitive zone.
    What are the steps taken by the Indian Government?

    •  Seismic Zoning and Monitoring: India is divided into four seismic zones (II to V) to prioritize risk-based planning. The National Centre for Seismology (NCS) monitors seismic activity across the country in real-time.
    • Implementation of Earthquake-Resistant Building Codes: The Bureau of Indian Standards (BIS) has issued IS codes for earthquake-resistant construction.
    • Capacity Building and Public Awareness: NDMA and NDRF conduct training, mock drills, and awareness programs in vulnerable areas.

    Way forward: 

    • Integrated Land and Water Management: Promote sustainable groundwater use, recharge practices, and land-use planning to reduce land subsidence and seismic vulnerability.
    • Expand Monitoring and Preparedness: Enhance seismic monitoring networks and public awareness programs to improve early warning systems and disaster resilience.

  • [17th July 2025] The Hindu Op-ed: A tectonic shift in thinking to build seismic resilience

    PYQ Relevance:

    [UPSC 2015] Earthquakes along the plate margins are still a cause of concern. India’s preparedness for mitigating their impact has significant gaps. Discuss various aspects.

    Linkage: The article emphasizes that India’s seismic risk is rooted in the northward drift of the Indian Plate colliding with the Eurasian Plate, which shaped the Himalayas and makes the region “overdue for a ‘Great Himalayan Earthquake’.  The question specifically mentions “earthquakes along the plate margins” and critically highlights “India’s preparedness for mitigating their impact has significant gaps.

     

    Mentor’s Comment:  The 4.4 magnitude tremor in Delhi on July 10, 2025, though moderate, exposed the critical fragility of India’s infrastructure, especially in Delhi, where over 80% of buildings violate seismic safety norms. This event is part of a wider pattern of seismic activity across Asia, underlining the urgent need for earthquake preparedness. India, particularly northern and northeastern regions, lies in high-risk seismic zones (IV & V) due to the collision of tectonic plates, making a massive quake imminent. Urbanisation, outdated construction, and poor enforcement of seismic codes like IS 1893:2016 worsen the risk.

    Today’s editorial analyses the vulnerability to earthquakes in India. This topic is important for GS Paper I (Geography) and  GS Paper III (Disaster Management) in the UPSC mains exam.

    _

    Let’s learn!

    Why in the News?

    On July 10, 2025, a 4.4 magnitude earthquake struck near Delhi, exposing the fragile state of infrastructure.

    Why is Delhi vulnerable to earthquakes?

    • High Seismic Risk Zone: Delhi lies in Seismic Zone IV, indicating a severe seismic hazard with a peak ground acceleration (PGA) of around 0.24g. Eg: Similar Zone IV cities like Srinagar and Patna have experienced strong tremors in the past.
    • Poor Structural Compliance: Over 80% of buildings in Delhi, especially those constructed before 2000, do not comply with seismic safety codes. Eg: Unregulated high-rise apartments in East Delhi lack ductile detailing or shear walls, making them prone to collapse.
    • Liquefaction-Prone Areas: Areas like East Delhi and Yamuna floodplains are built on soft alluvial soils, which are susceptible to liquefaction during earthquakes. Eg: In the 2001 Bhuj earthquake, structures on soft soil experienced severe tilting and collapse.
    • Rapid Urbanisation Without Planning: Delhi’s urban sprawl and dense population (over 33 million) have led to haphazard construction, often violating zoning and structural norms. Eg: Many illegal colonies like those in outer Delhi lack any seismic design considerations.

    What are the vulnerable areas in India? 

    • Himalayan Region: The Himalayan belt is highly prone to earthquakes due to the collision of the Indian and Eurasian tectonic plates. Eg: Regions like Jammu & Kashmir, Himachal Pradesh, Uttarakhand, and parts of Northeast India fall under Seismic Zone V.
    • Indo-Gangetic Plain: This region experiences significant seismic activity due to the tectonic stress transfer from the Himalayan region. Eg: Parts of Bihar, Uttar Pradesh, Delhi, and West Bengal lie in Seismic Zones III and IV.
    • Peninsular India Fault Zones: Though considered geologically stable, intraplate faults in Peninsular India can still trigger strong earthquakes. Eg: Areas like Latur (Maharashtra), Koyna (Maharashtra), and Bhuj (Gujarat) have witnessed major quakes in the past.

    What are the steps taken by the Indian Government? 

    • Building Code Reforms: The government enforces Earthquake-Resistant Building Codes to ensure structural safety in seismic zones. Eg: The Bureau of Indian Standards (BIS) revised IS 1893 and IS 4326 to include updated seismic design norms across construction sectors.
    • National Seismic Zoning: India has been zoned into seismic risk areas to guide planning and construction based on earthquake vulnerability. Eg: The country is divided into Zone II to Zone V, with Zone V (like parts of Uttarakhand, Kashmir) being most earthquake-prone.
    • Disaster Management Framework: The government has established a dedicated institutional framework to coordinate disaster preparedness and response. Eg: The National Disaster Management Authority (NDMA) issues guidelines for earthquake risk mitigation and conducts regular mock drills and capacity-building programs.

    What are the steps taken at the international level?

    • Sendai Framework for Disaster Risk Reduction (2015–2030): The United Nations adopted this global framework to strengthen disaster preparedness, promote resilient infrastructure, and reduce disaster losses. Eg: Countries like Japan and Chile have aligned their national disaster policies with Sendai priorities, emphasizing risk governance and early warning.
    • Global Seismic Hazard Assessment Program (GSHAP): Led by the International Lithosphere Program, this initiative provides seismic hazard maps to help countries plan safer infrastructure. Eg: Italy and other European nations use GSHAP data to revise building codes and zoning laws in earthquake-prone zones.
    • Early Warning Systems and Technology Sharing: Countries are collaborating to develop earthquake early warning systems and share real-time seismic data across borders. Eg: The Pacific Tsunami Warning Center and Japan’s Earthquake Early Warning System help neighbouring nations prepare faster for seismic events.

    What global lessons can India adopt from other countries? (Way forward)

    • Building Code Enforcement: Strong and regularly updated building codes ensure that infrastructure can withstand seismic shocks, reducing casualties and damage. Eg: After the 1995 Kobe earthquake, Japan revised its seismic building codes, which helped limit destruction during the 2011 Tōhoku earthquake.
    • Early Warning Systems: Timely alerts enable people to take quick protective actions, such as evacuation or shutting down utilities, before the shaking begins. Eg: In 2017, Mexico City’s SASMEX system gave a 20-second alert before the quake struck, allowing residents to prepare.
    • Retrofitting Incentives: Providing financial support for retrofitting older buildings motivates citizens to strengthen structures against earthquakes. Eg: The Earthquake Brace + Bolt program in California offers funds to homeowners, promoting structural safety in vulnerable areas.

  • In news: Great Trigonometric Survey (GTS)

    Why in the News?

    This newscard highlights the role of Indian assistants in completing the Great Trigonometric Survey (GTS), which began in 1802 to map India’s geography.

    About the Great Trigonometrical Survey (GTS):

    • Launch and Objective: The GTS was a massive scientific and cartographic initiative launched in 1802 by the British to map India with unprecedented precision using trigonometry and geodesy.
    • Initiator: It was conceptualised by William Lambton, a British army officer, and carried out under the East India Company.
    • Purpose: It aimed to measure Earth’s curvature, create accurate maps, and support colonial administration, scientific research, and military planning.
    • Survey Method: It used triangulation, involving a network of interconnected triangles built from a known baseline to calculate distances and angles over large areas.
    • First Baseline: The initial baseline was measured in 1802 at St. Thomas Mount near Madras (Chennai) and extended over 2,600 km up to the Himalayas.
    • Instruments Used: The survey used massive theodolites (weighing up to half a ton) and measuring chains, requiring large teams for operation and transport.
    • Scientific Outcome: It led to the formulation of the Everest Spheroid, a geodetic reference model still used for mapping in South Asia.
    • Duration and Leadership: Although planned to take 5 years, the project lasted nearly 70 years (until 1871) and was led by successors such as George Everest (after whom Mt. Everest was named), Andrew Scott Waugh, and James Walker.

    How did the GTS led to the Mapping of India?

    • First Accurate Maps: It provided scientific maps that corrected earlier errors, enabling modern geodetic frameworks for administration and infrastructure.
    • Survey Range: It mapped from southern India to the Himalayas, supporting large-scale development and scientific measurement.
    • Great Arc Measurement: It measured the Great Arc (Chennai to Dehradun), a significant geodetic arc that helped calculate Earth’s curvature.
    • Himalayan Heights: Using triangulation data, the survey measured 79 Himalayan peaks, including Mount Everest, K2, and Kangchenjunga.
    • Mount Everest Identification: In 1852, Peak XV was identified as the world’s highest mountain, later named Mount Everest in honour of George Everest.
    • Latitude-Longitude System: It produced precise longitude and latitude coordinates, crucial for navigation, military logistics, and administration.
    • Infrastructure Impact: Survey benchmarks supported railways, roads, canals, and earthquake studies, many of which remain relevant today.

    Contribution of Indians to the GTS:

    • Syed Mir Mohsin Husain: A jeweller from Arcot who repaired critical instruments and was later appointed as an instrument maker in the Surveyor General’s office.
    • Radhanath Sikdar: An Indian mathematician who calculated the height of Mount Everest in 1852, confirming it as the tallest peak globally.
    • Indian Field Workers: Thousands of Indian flagmen, khalasis, and labourers undertook challenging tasks like carrying heavy equipment, setting markers, and working in hazardous environments.
    • Logistical Support: Indian artisans and technicians repaired, calibrated, and adapted instruments, making the project feasible under Indian conditions.
    • Role of Pundits: Trained Indian “pundits” conducted secret surveys in Tibet and politically sensitive regions, where British officers were restricted.
    [UPSC 2018] Among the following cities, which one lies on a longitude closest to that of Delhi?

    Options: (a) Bengaluru* (b) Hyderabad (c) Nagpur (d) Pune

     

  • In news: Seine River

    Why in the News?

    French authorities have opened up the Seine River to public swimming for the very first time since 1923.

    In news: Seine River

    About the Seine River:

    • Overview: it is a major waterway in northern France, flowing through some of the country’s most important cultural and economic regions.
    • Length and Rank: It is approximately 777 km(483 miles) long, making it the second-longest river in France after the Loire.
    • Source and Elevation: It originates from the Langres Plateau in the Burgundy region, near the town of Source-Seine, at an elevation of about 444–471 meters above sea level.
    • Course Through France: It flows northwest, passing through regions such as Burgundy, Champagne, and Île-de-France, and cities like Troyes, Melun, Corbeil, and Paris.
    • Path Through Paris: In Paris, the Seine winds through the city center for about 13 kilometers, forming the famous islands Île de la Cité and Île Saint-Louis.
    • Tributaries: It is joined by several important tributaries, including the Marne, Yonne, Aube, and Oise rivers.
    • Drainage Basin and Rainfall: Its drainage basin spans 76,000–79,000 square kilometers, receiving moderate rainfall of 650–750 mm annually, and covering much of northern France.
    • Mouth and Termination: The river empties into the English Channel between Le Havre and Honfleur, on the Normandy coast.
    • Economic Role: The Seine supports commercial navigation and shipping, especially through the ports of Rouen and Le Havre, and provides about 50% of Paris’s drinking water.
    [UPSC 2020] Consider the following pairs: River Flows into

    1. Mekong Andaman Sea 2. Thames Irish Sea 3. Volga Caspian Sea 4. Zambezi Indian Ocean Which of the pairs given above is/are correctly matched?

    Options: (a) 1 and 2 only (b) 3 only (c) 3 and 4 only* (d) 1, 2 and 4 only

     

  • How India ‘added’ more than 3,500 km to its coastline

    Why in the News?

    India’s coastline has increased by about 48%, not because of new land but due to better digital mapping and updated measurements. It has grown from 7,516 km to 11,098 km, giving a clearer view of the country’s natural borders.

    What led to the increase in India’s measured coastline length?

    • Use of High-Resolution Mapping Technology: The shift from low-resolution (1:4,500,000) to high-resolution data (1:250,000) allowed finer measurement of the coastline’s bends and curves. Eg: Modern GIS software captured intricate coastal shapes that older manual methods missed.
    • Inclusion of Previously Omitted Offshore Islands: Many small offshore islands that were earlier not visible or excluded due to manual limitations are now included. Eg: Several minor islands around the Andaman & Nicobar and Lakshadweep regions added extra coastline length.
    • Coastline Paradox and Irregularity of Landforms: Coastlines are naturally irregular; measuring them at a finer scale captures more detail, thus increasing total length. Eg: Like using a one-meter ruler instead of a one-kilometre one—more small features are counted, increasing overall length.

    Why is the coastline paradox relevant to India’s coastal mapping?

    • Scale-Dependent Measurement: The coastline paradox shows that a coastline’s length varies based on the scale or resolution used for measurement—the finer the scale, the longer the coastline appears. Eg: Measuring with 1:250,000 scale data gives a much longer length than with 1:4,500,000 scale data.
    • Irregular Nature of Coastlines: Coastlines are highly irregular, full of bends, curves, and inlets, which get missed at lower resolutions but captured at higher ones. Eg: A low-resolution map smooths out land features, while high-resolution GIS tools map every minor curve.
    • No Fixed Length: The paradox proves that coastlines do not have a finite length—they can always be measured in more detail, leading to ever-changing figures. Eg: Even with current high-tech tools, the actual coastline length keeps increasing with better precision in future reassessments.

    How does reassessing the coastline and islands impact governance and security?

    • Accurate Administrative and Developmental Planning: Reassessment provides a clear understanding of territorial boundaries, aiding in efficient governance and infrastructure development. Eg: Updated coastline data helps plan coastal roads, ports, and disaster response systems in states like Gujarat and West Bengal.
    • Strengthening Maritime Security and Surveillance: Precise mapping helps in identifying vulnerable points, enabling better deployment of naval and coast guard resources. Eg: Mapping of remote islands assists in setting up radar stations and surveillance posts in regions like Lakshadweepand Andaman & Nicobar.
    • Strategic Assertion and Environmental Management: Helps in asserting sovereignty over maritime zones and managing coastal ecosystems more effectively. Eg: Reassessment supports India’s claim over its Exclusive Economic Zone (EEZ) and strengthens climate resilienceplanning in coastal areas.

    What challenges exist in accurately counting India’s offshore islands?

    • Ambiguity in Definitions and Tidal Variations: Some landforms may appear as islands during high tide but get connected to the mainland during low tide, causing confusion in classification. Eg: Certain coastal features in Sundarbans and Gulf of Khambhat shift between island and non-island status based on tide levels.
    • Discrepancies Across Agencies and Lack of Standardisation: Different agencies like state governments, Coast Guard, and Surveyor General have reported varying island countsdue to inconsistent definitions and methods. Eg: In 2016, the Surveyor General listed 1,382 islands, while other agencies reported 1,334, leading to a need for data reconciliation.

    Way forward: 

    • Standardised Methodology and Regular Reassessment: Adopt a uniform classification system for islands and coastlines across all agencies, and institutionalise periodic reassessments using high-resolution GIS and satellite data every 10 years.
    • Integrated Coastal Management and Strategic Mapping: Develop a centralised coastal database linking administrative, ecological, and security data to support policy-making, climate resilience, and maritime defence planning.

    Mains PYQ:

    [UPSC 2024] In a crucial domain like the public healthcare system, the Indian State should play a vital role to contain the adverse impact of marketisation of the system. Suggest some measures through which the State can enhance the reach of public health care at the grassroots level.

    Linkage: This article explicitly highlights alcohol consumption as a significant public health issue in India, leading to injuries, mental illness, non-communicable diseases like cancer, and contributing to approximately 2.6 million Disability-Adjusted Life Years (DALYs) in 2021.

  • Shipki La Mountain Pass opened for Tourists

    Why in the News?

    For the first time since India’s independence, the Shipki La pass in Himachal Pradesh has been opened to domestic tourists, marking a historic shift in India’s border tourism strategy.

    About Shipki La Pass:

    • It is a high-altitude mountain pass at 3,930 meters in the Kinnaur district of Himachal Pradesh, on the India–Tibet (China) border.
    • It is one of only 3 official border trading points between India and Tibet, along with Nathu La (Sikkim) and Lipulekh (Uttarakhand).
    • The Sutlej River (called Langqen Zangbo in Tibet) enters India near Shipki La, adding geographical importance to the area.
    • The pass lies along National Highway 5 (NH5) and is considered one of the highest motorable roads in India.
    • Historically, it served as a major trade route, enabling exchange of salt, wool, spices, yak tails, and tea between India and Tibet.
    • Trade was stopped in 1962 after the India-China war, resumed in 1992, but was halted again during COVID-19.
    • On June 9, 2025, Himachal Pradesh opened the pass to Indian tourists for the first time since Independence.
    • The initiative is part of a “Border Tourism” strategy, which includes the launch of the Sarhad Van Udyan (Border Forest Park).
    • It is also being considered as an alternate route for the Kailash Mansarovar Yatra.

    Other Important Himalayan Passes:

    • Ladakh and Jammu & Kashmir:
      • Khardung La (5,359 m) – Among the highest motorable passes; connects Leh with Nubra Valley.
      • Zoji La – Links Srinagar with Leh; vital for year-round Ladakh access.
      • Chang La, Baralacha La, Umling La (5,798 m) – Crucial for Leh connectivity and defense.
      • Rezang La – Famous for the 1962 India-China war battle.
      • Karakoram Pass, Aghil Pass, Demchok Pass – Strategic India-China border passes.
    • Himachal Pradesh:
      • Rohtang Pass – Connects Kullu with Lahaul-Spiti; key for tourism and logistics.
      • Parang La – Links Spiti Valley and Parvati Valley; used by trekkers and herders.
      • Shipki La – Now open to tourists; historical Indo-Tibetan trade route.
    • Uttarakhand:
      • Lipulekh Pass (5,632 m) – Used for Kailash Mansarovar Yatra.
      • Mana Pass – One of the highest vehicle-accessible passes; connects to Tibet.
      • Niti Pass, Milam Pass, Kuthi Pass – Historical trade and pilgrimage routes.
    • Sikkim:
      • Nathu La – Major border trade route; part of the ancient Silk Route.
      • Jelep La – Historical route linking Sikkim with Lhasa via Chumbi Valley.
    • Arunachal Pradesh:
      • Se La, Bum La – Connect to Tawang and Bhutan border.
      • Pangsau Pass, Diphu Pass – Connect Arunachal with Myanmar; important for WWII history and connectivity.
    [UPSC 2007] Which one of the following Himalayan passes was reopened around in the middle of the year 2006 to facilitate trade between India and China?

    Options: (a) Chang La (b) Jara La (c) Nathu La (d) Shipki La

     

  • Places in news: Mt. Khangchendzonga

    Why in the News?

    Sikkim’s CM has asked the Centre to ban climbing on Mt. Khangchendzonga, even from the Nepal side, as the mountain is sacred to the Sikkimese and seen as a guardian deity.

    About Mt. Khangchendzonga:

    • Location: Mt. Khangchendzonga is the third-highest mountain in the world at 8,586 metres, located on the India-Nepal border in the eastern Himalayas.
    • Major Glaciers and Rivers: It is surrounded by Zemu, Talung, Yalung, and Kanchenjunga glaciers and bordered by rivers like Tamur, Lhonak, and Teesta.
    • Etymology: Known as the “Five Treasuries of the Great Snow”, due to its five towering peaks, all above 8,000 metres.
    • Geological Age: The mountain rocks are between 445 million to 1 billion years old, from the Neoproterozoic to Ordovician periods.
    • Ecological Zone: Located within Khangchendzonga National Park, a UNESCO World Heritage Site, rich in altitude diversity and rare species.
    • Wildlife and Ecosystems: Home to snow leopards, red pandas, musk deer, and Asiatic black bears, along with over 220 glacial-fed water bodies.
    • Hydrological Importance: It is the highest point in the Brahmaputra basin, contributing water to both the Ganges and Kosi River systems.
    • Climate: Receives heavy monsoon snowfall and lighter winter snow.

    Religious and Cultural Significance:

    • Spiritual Status: The mountain is sacred in Sikkim and Nepal, embedded in local mythology and Buddhist traditions.
    • Symbolism of the Name: The “5 Treasuries” are believed to hold salt, gold, turquoise, sacred texts, grain, medicine, and other treasures.
    • Guardian Deity: It is considered the home of Dzoe-Nga, the chief protector deity of Sikkim, known as Pho-lha.
    • Mythological Roots: Local guardian deities were blessed by Guru Padmasambhava, the patron saint of Sikkim.
    • Climbing Ban: The Sikkim government banned climbing on the mountain in 1998 and 2001 under the Sacred Places of Worship Act, 1991, to preserve its sanctity.
    [UPSC 2024] Consider the following pairs:

    Peak: Mountains

    1. Namcha Barwa — Garhwal Himalaya

    2. Nanda Devi — Kumaon Himalaya

    3. Nokrek — Sikkim Himalaya

    Which of the pairs given above is/are correctly matched?

    Options: (a) 1 and 2 (b) 2 only* (c) 1 and 3 (d) 3 only

     

  • What is Madden-Julian Oscillation (MJO)?

    Why in the News?

    Mumbai got heavy monsoon rains two weeks early because of a strong Madden-Julian Oscillation (MJO) — a weather pattern that boosts rainfall in the region.

    About the Madden-Julian Oscillation (MJO):

    • Definition: The MJO is a moving weather system of clouds, wind, rain, and pressure that travels eastward around the tropics.
    • Cycle Time: It takes 30 to 60 days to complete a full loop around the globe.
    • Discovery: It was discovered in the 1970s by Roland Madden and Paul Julian.
    • Two Phases:
      1. The enhanced convective phase brings heavy rain, storms, and clouds.
      2. The suppressed convective phase brings dry, clear weather.
    • Global Pattern: These phases move together — when one area gets rain, another gets dry weather.
    • MJO vs ENSO: Unlike El Niño, which lasts for months, the MJO changes every few weeks and affects short-term weather patterns.
    • Wider Impact: It influences monsoons, cyclones, jet streams, and weather in both tropical and non-tropical regions.
    • Phases: Scientists divide its movement into 8 phases, each showing where rain or dry weather will occur.

    MJO and the Early Monsoon of 2025:

    • Early Monsoon Trigger: The early arrival of the monsoon in May 2025 was largely due to a very active MJO.
    • IMD Observation: The India Meteorological Department noted that the MJO was in Phase 4 with high amplitude, which strongly affects Indian rainfall.
    • Rapid Monsoon Progress: It helped push extra moisture and clouds from the Indian Ocean, making the monsoon move from Kerala to Maharashtra in just two days.
    • Other Contributing Factors:
      • A strong cross-equatorial flow brought warm, moist air from the south.
      • A low-pressure system in the Arabian Sea brought pre-monsoon rains to Mumbai.
    • Record Rainfall: This resulted in Mumbai’s wettest May in over 100 years.
    • Why It Matters: The event showed how a tropical system like the MJO can suddenly change monsoon timing and rainfall patterns in India.
    [UPSC 2017] With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?

    1. IOD phenomenon is characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.

    2. An IOD phenomenon can influence an El Nino’s impact on the monsoon.

    Options: (a) 1 only (b) 2 only* (c) Both 1 and 2 (d) Neither 1 nor 2

     

  • [26th May 2025] The Hindu Op-ed: The maths of how India’s coastline lengthened without gaining land

    PYQ Relevance:

    [UPSC 2023] Comment on the resource potentials of the long coastline of India and highlight the status of natural hazard preparedness in these areas.

    Linkage: India’s geography and physical features, like its coastlines, are often discussed in terms of resources and natural hazards. This question is relevant as it pertains to India’s coastline and is categorized under the Geography subject in GS1.

     

    Mentor’s Comment: In December 2024, the Union Ministry of Home Affairs revised India’s coastline length from 7,516.6 km to 11,098.8 km, not due to any geographical change, but because of the use of advanced cartographic tools and improved measurement techniques. This revision, made nearly 50 years after the original measurement in the 1970s, demonstrates the coastline paradox — the idea that coastline length increases with more detailed measurement scales. The update has significant implications for maritime security, disaster preparedness, and exclusive economic zone delineation, showcasing how technology redefines our geographic understanding.

    Today’s editorial discusses the updated length of India’s coastline and its effects. This information is useful for GS Paper I (Geography), GS Paper II (Policy Making), and GS Paper III (Environment & Disaster Management).

    _

    Let’s learn!

    Why in the News?

    The Ministry of Home Affairs updated India’s coastline length to 11,099 km in its 2023–24 report, increasing it from the earlier measurement of 7,516.6 km.

    What caused the increase in India’s coastline length?

    • Use of High-Resolution Mapping Techniques: Earlier measurements (1970s) used low-resolution maps (1:4,500,000), missing finer features. The updated 2024 figure uses high-resolution charts (1:250,000), capturing detailed coastal geometry. Eg: Narrow tidal creeks and sandbars that were previously omitted are now included.
      • Features like estuaries, tidal flats, coastal ridges, and inlets are now accurately mapped. Eg: Island groups like Andaman & Nicobar and Lakshadweep, which were inadequately covered earlier, are now comprehensively included.

    Why is it hard to measure coastlines accurately?

    • Coastline Paradox (Dependence on Scale of Measurement): The measured length of a coastline changes based on the size of the measuring unit (“ruler”). Eg: Using a 200-km ruler smooths over small curves, but a 1-km ruler captures every inlet and estuary, increasing total length.
    • Irregular and Dynamic Coastal Features: Coastlines are shaped by natural features like creeks, deltas, estuaries, and shifting sediments, which are not fixed. Eg: River mouths may change shape over time due to erosion or sediment deposition, making boundaries unclear.
    • Influence of Tides and Sea-Level Changes: High and low tides alter visible land boundaries, affecting measurements at different times. Eg: Areas that are exposed during low tide but submerged at high tide (like mudflats) may or may not be counted depending on timing.

    Which tools were used to update the measurement?

    • Electronic Navigation Charts (ENCs): Provided detailed and accurate mapping at a finer scale (1:250,000). Eg: These charts helped capture small features like estuaries and creeks which were missed in older maps (1:4,500,000 scale).
    • Geographic Information Systems (GIS): Enabled spatial analysis and integration of various data layers for precise mapping. Eg: GIS combined data from satellites, surveys, and field measurements to create a more accurate coastline outline.
    • LIDAR-GPS and Satellite-Based Imaging: Laser-based LIDAR and GPS were used for high-resolution topographic mapping. Eg: Drones and satellite altimetry helped detect elevation and shoreline changes, especially in island regions like Andaman & Nicobar.

    How does the revised coastline length impact India’s maritime security and disaster preparedness?

    • Enhanced Maritime Surveillance and Border Security: A longer coastline means more area to monitor for smuggling, infiltration, and illegal fishing. Eg: The Indian Coast Guard may need more outposts, vessels, and patrol routes to guard the extended 11,099.8 km coastline.
    • Expansion of Exclusive Economic Zone (EEZ): The increased length helps in demarcating a wider EEZ, enabling better control over marine resources. Eg: India can assert rights over fisheries, oil, and gas exploration in a broader sea area.
    • Improved Disaster Preparedness and Early Warning: Better understanding of coastal geography aids in creating precise models for cyclones, tsunamis, and storm surges. Eg: Coastal States like Odisha and Tamil Nadu can now develop more accurate evacuation and shelter plans.
    • Refined Coastal Regulation and Zoning: Accurate coastline data supports zoning laws to restrict construction in vulnerable areas. Eg: Authorities can update Coastal Regulation Zone (CRZ) norms to better safeguard ecosystems and infrastructure.
    • Better Climate Resilience and Adaptation Planning: Updated coastline measurements help assess vulnerability to sea-level rise and erosion. Eg: Low-lying areas in Kerala and island regions like Lakshadweep can be prioritized for climate adaptation projects.

    What are the resource potentials of the long coastline of India?

    • Fisheries and Marine Biodiversity: India’s coastline supports a vast fishing industry, providing employment and food security. Eg: States like Gujarat and Tamil Nadu have thriving marine fishing sectors contributing to exports and coastal livelihoods.
    • Port Infrastructure and Trade: The long coastline facilitates maritime trade through major and minor ports. Eg: Ports like Mumbai, Chennai, and Visakhapatnam are crucial for imports, exports, and shipping connectivity under the Sagarmala Project.
    • Offshore Energy Resources: Coastal waters have potential for oil, natural gas, and renewable energy like offshore wind and tidal energy. Eg: Mumbai High is a major offshore oil field, while Gujarat and Tamil Nadu are exploring offshore wind energy projects.
    • Tourism and Blue Economy Development: Scenic beaches, islands, and marine ecosystems attract tourism and support the blue economy. Eg: Goa’s coastal tourism and the Andaman & Nicobar Islands’ ecotourism contribute significantly to local economies.
    • Aquaculture and Coastal Agriculture: Coastal zones are suitable for shrimp farming, seaweed cultivation, and salt production. Eg: Andhra Pradesh and West Bengal have developed large-scale shrimp aquaculture for domestic and export markets.

    What is the status of natural hazard preparedness in the coastal Area?

    • Improved Early Warning Systems: India has strengthened early warning capabilities for cyclones and tsunamis through institutions like the Indian National Centre for Ocean Information Services (INCOIS) and IMD. Eg: The Odisha government’s timely evacuation during Cyclone Fani (2019) saved thousands of lives.
    • Development of Coastal Infrastructure and Shelters: Construction of cyclone-resistant shelters, embankments, and flood control systems has improved disaster resilience. Eg: The National Cyclone Risk Mitigation Project (NCRMP) has led to the building of multi-purpose cyclone shelters in vulnerable states like Andhra Pradesh and West Bengal.
    • Community Awareness and Disaster Drills: Government and NGOs have promoted community-based disaster preparedness, training locals in evacuation procedures and first aid. Eg: Regular mock drills in coastal villages of Tamil Nadu and Kerala help improve response readiness.

    Way forward: 

    • Integrated Coastal Zone Management (ICZM) Expansion:Strengthen ICZM plans across all coastal states with real-time monitoring, climate-resilient infrastructure, and ecosystem-based approaches. Eg: Expand initiatives like ICZM Phase II to include mangrove restoration, sustainable livelihoods, and coastal erosion control in states like Kerala and Goa.
    • Technology-Driven Risk Mapping and Community-Centric Planning: Deploy AI-powered hazard models, geospatial mapping, and mobile-based alert systems to ensure last-mile connectivity. Eg: Use drone mapping for vulnerable areas in the Sundarbans, and integrate local communities into planning via participatory risk assessments.