INTEGRATED MAINS AND PRELIMS MENTORSHIP (IMPM) KEY (05/09/2025)

INTEGRATED MAINS AND PRELIMS MENTORSHIP (IMPM) 2025 Daily KEY

 
 
 
 
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India-China border Dispute and Antimicrobial resistance (AMR) and its significance for the UPSC Exam? Why are topics like GST council,  Registrar General of India (RGI) , High Seas Treaty important for both preliminary and main exams? Discover more insights in the UPSC Exam Notes for September 05, 2025

 
 
 
For Preliminary Examination:   Current events of national and international Significance
 
For Mains Examination:  GS II - International relations
 
Context:
 
India has a complicated history with regards to its border with China. The border was the product of two empires — the Manchu and the British. Being in the Himalayas and in an unpopulated area, it was not precise.
 
Read about:
 
Sino-Indian border
 
Line of Actual Control (LAC)
 
 
Key takeaways:
 
 

India–China Border Dispute: A Historical Overview

Colonial Legacy and Early Disagreements

  • India’s boundary with China has its roots in the territorial divisions created by the British and the Manchu empires. Since the region lay across the remote and sparsely populated Himalayas, the demarcation was never clearly established.
  • After Independence, both nations should ideally have worked out a precise border agreement. However, India maintained that the boundaries were already defined by British-era maps, without considering the absence of effective ground control.

The Origins of Conflict

  • Neither country had permanent settlements in Aksai Chin, a desolate high-altitude desert. China, seeking easier access to Tibet, built a road through Aksai Chin and asserted control.
  • India, on the other hand, took charge of Tawang in present-day Arunachal Pradesh, relying on the 1914 Simla Agreement with Tibet, which outlined the McMahon Line as the boundary.
  • China repeatedly suggested ways to resolve the dispute. In 1959, it proposed accepting a Line of Actual Control (LAC) with mutual withdrawals of 20 km.
  • In 1960, Premier Zhou Enlai suggested a compromise: China would keep Aksai Chin, while recognising India’s sovereignty over Arunachal Pradesh. India rejected these proposals, remaining firm on its territorial claims.
  • Later attempts to reassert control over Aksai Chin escalated tensions, eventually leading to the 1962 war. While China withdrew in the east beyond the McMahon Line, it retained portions of Ladakh captured during the war.

Post-war Period and Renewed Engagement

  • For nearly 15 years, both sides avoided direct engagement along the border. In 1975, India set up the China Study Group to monitor the frontier, marking patrol points with the help of satellite imagery.
  • In 1979, Foreign Minister Atal Bihari Vajpayee visited Beijing, the first high-level Indian visit since the war. Despite being cut short by China’s attack on Vietnam, the visit revived some diplomatic engagement.
  • China’s motivation was to prevent India from aligning too closely with the Soviet Union. Around this time, Deng Xiaoping revived Zhou’s earlier proposal, offering recognition of the McMahon Line in return for Indian acceptance of the existing situation in Ladakh. However, India—still wary after 1962—rejected such trade-offs.
  • By 1983, Beijing went further, suggesting that India concede not only Aksai Chin but also the areas occupied in 1962. Known as the ‘LAC Plus’ proposal, it too was declined.

Border Talks and Persistent Deadlocks

  • Formal border negotiations began in December 1981 but soon stalled. China pressed for a package deal, while India preferred a sector-by-sector approach. By 1985, Beijing hardened its stance, demanding concessions in the eastern sector—particularly Tawang, a significant Tibetan Buddhist centre that Tibet had controlled until well after 1914.
  • During the 1980s, occasional flare-ups occurred. Notably, the 1986 Wangdung incident prompted India’s Operation Falcon, which saw forward deployment of Indian troops along the LAC, surprising China and forcing de-escalation. The crisis, however, demonstrated India’s improved military preparedness compared to 1962.

Steps Towards Normalisation

  • By the mid-1980s, with Soviet power declining after its Afghan intervention, China shifted focus to counter India’s growing ties with the U.S. This led to Rajiv Gandhi’s landmark visit to Beijing in 1988, the first by an Indian Prime Minister since the conflict. Deng Xiaoping urged both sides to “forget the unpleasant past” and build good neighbourly relations.
  • Both countries agreed to strengthen cooperation in multiple areas while keeping the border issue on the back burner. A Joint Working Group (JWG) on the boundary question was set up, marking a shift from confrontation to managing differences through dialogue
 
Follow Up Question
 
1.“Belt and Road Initiative” is sometimes mentioned in the news in the context of the affairs of : (UPSC CSE 2016)
(a) African Union
(b) Brazil
(c) European Union
(d) China
 
Answer (d)
 
The Belt and Road Initiative (BRI) is China’s global infrastructure and connectivity project, launched in 2013, aimed at boosting trade and economic integration across Asia, Africa, and Europe through investments in roads, railways, ports, and energy pipelines
 
 
 
For Preliminary Examination:  Current events of health importance especially like antimicrobial resistance
 
For Mains Examination:  GS III - Science and Technology
 
Context:
As mental health awareness gains momentum in India, a surreptitious menace is insidiously undermining this edifice of progress: the unbridled use of antibiotics. Whilst the threat of antimicrobial resistance (AMR) is ubiquitously acknowledged as a formidable public health hazard, its profound implications on mental well being remain under examined
 
Read about:
 
Antimicrobial resistance (AMR)
 
INSAR (Indian Network for Surveillance of Antimicrobial Resistance)
 
 
Key takeaways:

Antibiotics, AMR and Mental Health: An Overlooked Connection

A Hidden Challenge

  • As India gradually strengthens its mental health awareness, another silent threat undermines this progress — the unchecked use of antibiotics.
  • While antimicrobial resistance (AMR) is widely recognised as a major public health concern, its consequences for mental well-being remain underexplored.
  • At the heart of this lies the gut-brain axis, a complex communication system between the digestive tract and the brain.

Antibiotic Overuse in India

  • India ranks among the world’s highest consumers of antibiotics. Easy over-the-counter availability, self-medication, and low public awareness have normalised their misuse.
  • The Institute for Health Metrics and Evaluation estimates that AMR caused nearly 2.67 lakh deaths in India in 2021, with projections rising to 1.2 million by 2030 if current patterns persist.
  • A 2022 study in The Lancet Regional Health – Southeast Asia reported that almost half of the antibiotics used in India were unapproved combinations, worsening resistance. Beyond fuelling AMR, such misuse disrupts gut microbiota, a key factor for mental health.

Gut and Mental Well-being

  • The human gut hosts trillions of microbes that influence neurotransmitters such as serotonin and dopamine — regulators of mood, sleep, and stress. When antibiotics disturb this microbial balance, it can affect brain function, potentially leading to psychiatric issues.
  • Research by institutions like NIMHANS and AIIMS has begun examining the role of gut imbalance in mental disorders. Though still evolving, evidence suggests a strong link, highlighting the need for early interventions.
  • The gut microbiome, often called the “second brain,” interacts with the nervous system through short-chain fatty acids, immune modulation, and vagus nerve signalling, thereby influencing mood and behaviour.

Emerging Therapies: Psychobiotics

  • The field of psychobiotics — probiotics and prebiotics that support mental health — is showing promise. A 2020 Frontiers in Psychiatry meta-analysis found that probiotics significantly reduced depressive symptoms, especially in mild to moderate cases.
  • This indicates the potential for gut-targeted therapies to complement psychiatric care in India, where mental health resources remain limited.

Gaps in Awareness and Systemic Issues

  • Most Indians remain unaware of the gut-brain link and the dangers of antibiotic misuse. The tendency to seek quick pharmaceutical fixes over lifestyle changes further entrenches this problem.
  • Rural and semi-urban regions, where healthcare is fragmented and regulation weak, face particular risks as antibiotics are often dispensed without prescriptions.
  • Additionally, economic incentives drive over-prescription. Doctors may prescribe antibiotics to meet patient expectations, while unregulated pharmacies sell them freely, deepening the AMR crisis.

Mental Health Impacts of Dysbiosis

  • Gut imbalance contributes to inflammation, linked to major depressive disorder. Elevated cytokines like IL-6 and TNF-alpha cross into the brain, disrupting neurotransmitters and plasticity. Gut-derived metabolites such as butyrate and propionate also influence brain gene expression and stress regulation.

Towards Solutions

  • This crisis demands a shift in understanding mental illness — not only as a brain disorder but also as a systemic condition connected to gut health. A multidisciplinary approach involving psychiatry, gastroenterology, nutrition, and public health is needed.
  • India’s culinary heritage, rich in fermented foods like curd, idli, dosa, and pickles, already offers natural probiotics that support microbial health. Public health campaigns under the National Health Mission and Ayushman Bharat can integrate gut-brain awareness, while school curricula can introduce microbiome science to the next generation.
  • Regulatory action is equally vital. The Central Drugs Standard Control Organization (CDSCO) must tighten antibiotic sale regulations, enforce prescription-only access, and penalise violations.
  • Surveillance networks such as INSAR should be expanded and linked with mental health indicators to inform better policies. Investing in India-specific microbiome research will further enable targeted therapies
 
Follow Up Question
 

1.Which of the following are the reasons for the occurrence of multi-drug resistance in microbial pathogens in India? ( UPSC CSE 2019)

  1. Genetic predisposition of some people
  2. Taking incorrect doses of antibiotics to cure diseases
  3. Using antibiotics in livestock farming
  4. Multiple chronic diseases in some people

Select the correct answer using the code given below.

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

Answer (b)
 
  • Genetic predisposition of some people (1) → ❌ Not related. Multi-drug resistance is due to microbial adaptation, not human genetics.

  • Taking incorrect doses of antibiotics (2) → ✅ Major reason; incomplete or wrong dosage promotes resistance.

  • Using antibiotics in livestock farming (3) → ✅ Contributes significantly, as resistant microbes can spread from animals to humans.

  • Multiple chronic diseases in some people (4) → ❌ Presence of chronic diseases doesn’t directly cause resistance.

👉 So, 2 and 3 only are correct

 
 
 
For Preliminary Examination:  Current events of national and international Significance
 
For Mains Examination: GS III - Economy
 
Context:
 
The Goods and Services Tax (GST) Council, in its 56th meeting which lasted over 10 hours Wednesday, cleared the next-generation reforms under the eight-year old indirect tax regime. 
 
 
Read about:
 
What is the role and function of the GST council?
 
What is the tax system in India?
 
 
Key takeaways:
 

The Goods and Services Tax (GST) regime was introduced in 2017 after the passage of the 122nd Constitutional Amendment Bill in 2016. It was designed to replace India’s complex tax structure — where both Centre and states levied multiple indirect taxes — with a uniform system.

The GST Council, established under Article 279A (1) of the Constitution, functions as a joint decision-making body of the Centre and the states. It includes the Union Finance Minister as Chairperson, the Union Minister of State for Finance, and one minister nominated by each state. As per Article 279, the Council recommends key decisions such as exempted goods/services, applicable GST laws, and rate changes.

Key Features of Recent GST Announcements

  • Rate Reductions: The Council announced significant cuts across daily-use items and household goods. Packaged food products (juices, cheese, butter, condensed milk, pasta, dates, coconut water, sausages), medical items (oxygen, gauze, diagnostic kits), and essentials like plain roti, paneer, and ultra-high temperature milk were moved to lower or nil tax slabs. Household items such as soaps, shampoos, toothpaste, hair oil, bicycles, and kitchenware shifted to 5% from higher rates.

  • White Goods: Items like air conditioners, TVs, and dishwashers were shifted to the 18% slab from 28%.

  • Automobiles: Small petrol and diesel cars under specified engine capacity and length now attract 18% GST.

  • Insurance: A complete exemption was granted for life and health insurance policies, including family floaters and senior citizen plans.

  • Services: Commonly used services — gyms, salons, yoga centres, barber shops — now face 5% GST instead of 18%.

Streamlining GST Structure

The reforms aim to simplify the multi-slab system (5%, 12%, 18%, 28%) into a two-rate structure:

  • A merit rate of 5%

  • A standard rate of 18%

  • Plus, a 40% special rate for luxury and demerit goods (tobacco, cigarettes, pan masala).

This rationalisation is expected to correct the inverted duty structure, where tax on output is lower than input, particularly affecting sectors like automobiles, textiles, and food processing.

Sector-specific Changes

  • In textiles, GST on man-made fibre and yarn was cut to 5% from 18% and 12% respectively.

  • Tobacco and related items will continue with cess until the government clears loans taken during the pandemic to compensate states.

Compensation Cess and Borrowing

  • The Centre borrowed ₹1.1 lakh crore (2020-21) and ₹1.59 lakh crore (2021-22) as back-to-back loans to offset cess shortfalls.

  • Repayments: ₹78,104 crore (2023-24), ₹1.24 lakh crore (2024-25), and ₹67,500 crore (2025-26).

  • In FY 2025-26, cess collections are projected at ₹1.67 lakh crore.

Economic Impact

While Finance Minister Nirmala Sitharaman stated it was premature to assess GDP impact, economists (HSBC, August 19) estimated a potential revenue loss of ₹1.43 lakh crore (0.4% of GDP) from the rate rationalisation exercise

 

Follow Up Question

1.Enumerate the indirect taxes which have been subsumed in the Goods and Services Tax (GST) in India. Also, comment on the revenue implications of the GST introduced in India since July 2017. (UPSC CSE 2019)

 

High Seas Treaty

For Preliminary Examination: Current events of national and international significance

For Mains Examination:  GS II - International Organisations

Context:

India will enact a new law to safeguard its interests in the international ocean waters following the finalisation of the High Seas Treaty two years ago.
 
Read about:
 
What are the high seas?
 
What is the significance of the high seas?
 

UNCLOS and the High Seas Treaty

It is not that oceans lack a governance framework. The 1982 UN Convention on the Law of the Sea (UNCLOS) provides a comprehensive legal structure for regulating conduct and usage of the world’s seas and oceans.

UNCLOS defines the rights and obligations of states with respect to maritime activities, including sovereignty, navigation rights, and economic usage. It also establishes boundaries such as territorial waters and Exclusive Economic Zones (EEZs).

  • Territorial Sea (TS): Extends up to 12 nautical miles from a country’s coastline. A state enjoys complete sovereignty within this zone.

  • Exclusive Economic Zone (EEZ): A state has sovereign rights only over economic resources below the sea surface, not full sovereignty over waters.

The convention lays down guiding principles for equitable access to resources and marine biodiversity conservation, but leaves implementation mechanisms vague.

The High Seas Treaty (BBNJ)

This gap is addressed by the High Seas Treaty, officially called the Biodiversity Beyond National Jurisdictions (BBNJ) Agreement. It acts as an implementation agreement under UNCLOS, much like the Paris Agreement under UNFCCC.

Key objectives of the treaty:

  • Restrict pollution and over-exploitation of resources.

  • Promote sustainable use of biodiversity in areas beyond national jurisdiction.

  • Establish marine protected areas in the high seas, similar to wildlife reserves on land.

Since the high seas — areas beyond territorial waters and EEZs — constitute nearly 64% of global ocean space, and are currently considered global commons, every nation enjoys equal rights of navigation, overflight, fishing, laying undersea cables, and resource extraction. The treaty seeks to regulate such activities, including seabed mining, while ensuring fair sharing of benefits from marine genetic resources.

India’s Role

India has signed the BBNJ but has not yet ratified it. Globally, 55 countries have ratified the agreement, which will take effect 120 days after the 60th ratification. Ratification does not require domestic legislation, but India has initiated steps to align with the treaty.

The Ministry of Earth Sciences has constituted a 12-member drafting panel, chaired by senior Supreme Court advocate Sanjay Upadhyay, to prepare a law that protects India’s maritime interests while ensuring the conservation of marine ecosystems

 
Follow Up Question
 

1.Concerning the United Nations Convention on the Law of Sea, consider the following statements: ( UPSC 2022)

  1. A coastal state has the right to establish the breadth of its territorial sea up to a limit not exceeding 12 nautical miles, measured from a baseline determined by the convention.
  2. Ships of all states, whether coastal or landlocked, enjoy the right of innocent passage through the territorial sea.
  3. The Exclusive Economic Zone shall not extend beyond 200 nautical miles from the baseline from which the breadth of the territorial sea is measured.

Which of the statements given above is correct?

A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
 
Answer (D)
 
  • Territorial Sea limit (12 nautical miles):
    Under UNCLOS, a coastal state can establish a territorial sea up to 12 nautical miles from the baseline. ✔️

  • Right of Innocent Passage:
    All ships, including those from landlocked states, have the right of innocent passage through a coastal state’s territorial waters. ✔️

  • Exclusive Economic Zone (EEZ):
    The EEZ extends up to 200 nautical miles from the baseline used for measuring the territorial sea. ✔️

Hence, all three statements are correct. ✅

 
 
 
For Preliminary Examination:   Current events of national and international Significance
 
For Mains Examination: GS II - Governance
 
Context:
 

Delhi High Court on Tuesday declined to grant bail to Umar Khalid, Sharjeel Imam, Gulfisha Fatima, and seven others charged as key conspirators of the February 2020 Delhi riots, saying the riots were a “premeditated, well-orchestrated conspiracy”.

The accused have been charged under various provisions of the Unlawful Activities (Prevention) Act, 1967 (UAPA), including Section 16, which prescribes the death penalty for committing a “terrorist act”

 

Read about:

Unlawful Activities (Prevention) Act, 1967 (UAPA)

What are the provisions of bail under UAPA?

 

Key takeaways:

 

UAPA: Definition of Terrorist Acts and Bail Provisions

  • Definition of Terrorist Act (Section 15):
    Under the Unlawful Activities (Prevention) Act (UAPA), a “terrorist act” is defined in Section 15. It is punishable with imprisonment ranging from a minimum of five years to life, and if the act results in death, the punishment may extend to death penalty or life imprisonment. This covers violent acts of a grave nature.

  • Scope of the Provision:
    The law criminalises any act carried out with the intention — or likelihood — of threatening the unity, integrity, sovereignty, security, or economic security of India, or to instill terror among people within India or abroad.
    It specifically lists activities such as the use of bombs, explosives, destruction of property, disruption of essential services, circulation of counterfeit currency, and acts that destabilise the economy.

  • Bail under UAPA (Section 43D(5)):
    Bail is extremely restrictive under the Act. The law states that an accused cannot be released if charged under Chapters IV and VI, unless the prosecution is heard. The test for denial of bail is whether there exists a prima facie case against the accused.
    In NIA v. Zahoor Ahmed Watali (2019), the Supreme Court clarified that courts should not assess the credibility or admissibility of evidence at the bail stage. Instead, they must accept the state’s case at face value, based on the “totality of circumstances.”

  • Application in Recent Case:
    The prosecution argued that the violence in question stemmed from a “well-planned conspiracy”, pointing to WhatsApp conversations, alleged “secret meetings,” and testimonies from “protected witnesses.” The incidents led to 54 deaths, including that of police and intelligence officials, and damage to over 1,500 properties.
    The accused countered that witness testimonies were vague, delayed, and unreliable. However, the court held that at the bail stage, evidence cannot be scrutinised for credibility and must be presumed true.

  • Threshold for Bail Denial:
    Courts apply a low threshold—if there are reasonable grounds to believe accusations are prima facie true, bail is denied. In this case, the High Court refused bail on that basis.
    Yet, the judgment also emphasised that the harshness of Section 43D(5) would be reconsidered if trials drag on unreasonably long and the accused have already served a significant portion of the maximum prescribed sentence

 

 Follow Up Question

1.Under Article 22 of the Constitution of India, with the exception of certain provisions stated there in, what is the maximum period for detention of a person under preventive detention? (MPSC 2014)

A. 2 months       

B. 3 months         

C. 4 months           

D. 6 months

Answer (B)
  • Article 22(3) of the Indian Constitution deals with preventive detention.

  • It allows a person to be detained without trial for preventive reasons, but only up to 3 months unless an advisory board (composed of judges) approves a longer detention.

  • The maximum period without the approval of an advisory board is therefore 3 months

 

 
 
 
For Preliminary Examination:  Current events of national and international Significance
 
For Mains Examination: GS III - Environment and Ecology
 
Context:
 
According to the Air Quality Life Index (AQLI) 2025 annual update, all of India lives in areas where the annual average particulate pollution level (PM2.5) exceeds the WHO annual average limit of 5 g/m³
 
Read about:
 
Air Quality Life Index (AQLI)
 
Particulate Matter (PM)
 
 
Key takeaways:
 
 
  • The Air Quality Life Index, curated by the Energy Policy Institute at the University of Chicago, stands as a compelling measure of how particulate matter (specifically PMâ‚‚.â‚…) affects human life expectancy.
  • It translates complex pollution data into a clear human context: how many years are taken away by breathing polluted air—making the invisible visible, and the impersonal personal
  • The 2025 edition of the AQLI report is built on data gathered in 2023 and conveys a stark global narrative: if world air quality were to meet the World Health Organization’s (WHO) benchmark of 5 µg/m³ PMâ‚‚.â‚…, the average person globally would gain an astounding 1.9 years of life.
  • This cumulative change amounts to a total of 15.1 billion life-years saved—a reminder that cleaner air isn’t just an environmental goal, but a lifeline

Global and Regional Highlights

  • South Asia remains the region with the most threatened lives due to polluted air. People there are losing an average of 3 years of life expectancy, with the most polluted areas seeing losses of over 8 years—making particulate pollution a deadlier risk than childhood and maternal malnutrition

  • In India, the national average life expectancy reduction due to air pollution stands at 3.5 years. This loss surpasses the impact of several other health threats—such as malnutrition (1.6 years), tobacco use (1.5 years), and even unsafe water and sanitation (less than a year)
  • Particularly alarming is New Delhi’s standing: residents of Delhi–NCR lose up to 8.2 years of life expectancy due to poor air quality—once more topping global rankings for the eighth consecutive report

Wildfires and Unexpected Trends

The 2025 AQLI data highlights a dramatic rise in pollution across North America—an unexpected reversal of trends. Canada experienced its worst wildfire season in history, and along with it, the U.S. saw PMâ‚‚.â‚… levels soar to heights not seen in years. This surge negated previous air quality gains and shifted the geography of pollution beyond traditional hotspots like California

Why AQLI Matters—and How It Helps

The AQLI isn’t just about numbers—it’s about awareness and accountability. By showing exactly how long polluted air can shave off our lives, it equips citizens, policymakers, and governments with the knowledge to act decisively. It illustrates how investments in clean air yield not only environmental returns but extended, healthier lives for populations everywhere

 

 Follow Up Question
 
1.In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index? (UPSC 2016)
  1. Carbon dioxide
  2. Carbon monoxide
  3. Nitrogen dioxide
  4. Sulfur dioxide
  5. Methane

Select the correct answer using the code given below:

A. 1, 2 and 3 only     

B. 2, 3 and 4 only   

C. 1, 4 and 5 only     

D. 1, 2, 3, 4 and 5

Answer (B)
 

The Air Quality Index (AQI) in India, calculated by the Central Pollution Control Board (CPCB) under the National Air Quality Monitoring Programme (NAMP), is based on 8 pollutants:

  1. Particulate Matter (PM10)

  2. Particulate Matter (PM2.5)

  3. Nitrogen Dioxide (NOâ‚‚)

  4. Sulphur Dioxide (SOâ‚‚)

  5. Carbon Monoxide (CO)

  6. Ozone (O₃)

  7. Ammonia (NH₃)

  8. Lead (Pb)

Now let’s match with the options given in the UPSC question:

  • Carbon dioxide (COâ‚‚) ❌ Not part of AQI.

  • Carbon monoxide (CO) ✅ Included.

  • Nitrogen dioxide (NOâ‚‚) ✅ Included.

  • Sulfur dioxide (SOâ‚‚) ✅ Included.

  • Methane (CHâ‚„) ❌ Not part of AQI

 

 
 
For Preliminary Examination:  Current events of national and international Significance
 
For Mains Examination:  GS I - Geography
 
Context:
 

A recent study has reconstructed the long-term discharge flow of the Gangotri Glacier System (GGS), the source of the upper Ganga basin which contributes to the waters of the Bhagirathi river in the central Himalayas. In the wake of climate change, glaciologists the world over have been studying the impact of glacier melt.

 
Read about:
 
Hindu Kush Himalaya (HKH)
 
Gangotri Glacier System (GGS)
 
 
Key takeaways:
 
  • The snow and ice reserves of the Hindu Kush Himalaya (HKH) play a vital role in feeding major river systems such as the Indus, Ganga, and Brahmaputra. In recent decades, however, the region has witnessed significant climatic variations that have reshaped the cryosphere and disrupted the hydrological cycle.
  • These changes have altered the functioning of glacier-fed river systems, leading to faster glacial retreat and shifts in seasonal water discharge. To understand these impacts, researchers often rely on modelling studies, which provide theoretical assessments of changing hydrological patterns.
  • Yet, due to the vast size of these river basins, it is difficult to accurately measure river flow and separate the contributions of snowmelt from that of rainfall. Smaller glacier systems, like the Gangotri Glacier System (GGS), offer a more manageable scale for such assessments, making them a preferred subject of study among hydrologists and climate scientists
  • The study reconstructed the long-term discharge patterns of the Gangotri Glacier System (GGS) using a high-resolution glacio-hydrological model known as Spatial Processes in Hydrology (SPHY).
  • This model simulates various components of the terrestrial water balance, including rainfall-runoff, evapotranspiration, and cryospheric processes. To enhance accuracy, it was combined with the Indian Monsoon Data Assimilation and Analysis (IMDAA) dataset covering the period from 1980 to 2020.
  • The results revealed that the GGS records its maximum discharge during the summer season, with a peak flow in July reaching about 129 cubic metres per second. On average, the annual discharge over the four decades was calculated at 28±1.9 m³/s, with snowmelt making the largest contribution (64%), followed by glacier melt (21%), rainfall-runoff (11%), and base flow (4%).
  • A decade-wise examination highlighted a shift in the discharge peak from August to July after the 1990s, a change linked to reduced winter precipitation and increased early summer melting.
  • Further, the mean decadal discharge indicated the sharpest rise—about 7.8%—between the periods 1991–2000 and 2001–2010. While the data reflected a steady rise in mean annual temperatures, there was no significant long-term trend in either annual precipitation or glacier melt.
  • Interestingly, snowmelt contributions declined despite warming, primarily due to a reduction in the average snow cover area. In contrast, both rainfall-runoff and base flow showed an increasing pattern from 1980 to 2020.
  • Statistical correlations from the study suggested that the mean annual discharge of GGS is primarily influenced by summer precipitation, with winter temperature being the secondary factor
  • Geographical Significance

    • Located in Uttarkashi district, Uttarakhand (Garhwal Himalayas).

    • Length: ~30 km; source of the Bhagirathi river, which merges with the Alaknanda to form the Ganga at Devprayag.

    • Snout: Gomukh (cow’s mouth shape).

    • Fed by tributary glaciers such as Raktvarn, Chaturangi, and Kirti.

  • Hydrological Importance

    • Acts as a major freshwater reserve sustaining the Ganga basin.

    • Discharge primarily contributed by snowmelt (64%), followed by glacier melt (21%), rainfall-runoff (11%), and base flow (4%) (1980–2020 study).

    • Peak discharge in July (~129 m³/s); average annual discharge: 28±1.9 m³/s.

  • Climatic and Environmental Trends

    • Observed glacial retreat due to rising temperatures and reduced snow cover.

    • Peak discharge shifted from August to July post-1990, caused by declining winter precipitation and enhanced early summer melting.

    • Decadal analysis shows highest discharge increase (7.8%) between 1991–2000 and 2001–2010.

    • Snowmelt contributions have declined despite warming, while rainfall-runoff and base flow increased.

  • Scientific Studies

    • Long-term hydrological modelling done using SPHY (Spatial Processes in Hydrology) model + IMDAA dataset (1980–2020).

    • Study published in the Journal of the Indian Society of Remote Sensing.

    • Found that summer precipitation is the primary control of annual discharge, followed by winter temperature.

  • Cultural & Strategic Importance

    • Considered a sacred origin of the Ganga in Hindu mythology.

    • Supports millions downstream in terms of drinking water, agriculture, and hydropower.

    • Serves as an indicator of climate change in the Himalayas.

Follow Up Question
 

1.When you travel in Himalayas, you will see the following: (UPSC CSE 2012)

  1. Deep gorges
  2. U-turn river courses
  3. Parallel mountain ranges
  4. Steep gradients causing land sliding

Which of the above can be said to be the evidence for Himalayas being young fold mountains?

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

 Answer (d)
 

The Himalayas are tectonically young and still rising, so you see:

  • Deep gorges and U-turn river courses where antecedent rivers kept their paths while the land uplifted.

  • Parallel mountain ranges (Shivalik, Himachal, Himadri) typical of young fold belts with limited denudation.

  • Steep gradients causing landslides, reflecting active uplift, high relief, and weak, folded rocks

 
 

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