• A study published in January 2025, based on field measurements, airmass trajectories, and particle dispersion simulations, concluded that there is no direct relationship between stubble-burning events in Punjab and Haryana and fine particulate matter (PM2.5) levels in Delhi-NCR.
• The research also highlights that crop residue burning in these states contributes only about 14% of PM2.5, making it a minor factor in the particulate matter concentration in the Delhi-NCR region.
• Despite a more than 50% reduction in stubble-burning events from 2015 to 2023, PM2.5 levels in Delhi-NCR remained stable, suggesting other factors at play. The findings were published in the journal Climate and Atmospheric Science.
• Since 2015, high-quality PM2.5 measurements have been conducted at the U.S. Embassy in New Delhi. While stubble-burning events in Punjab and Haryana decreased by 31% and 37% respectively in 2023 compared to the previous year, there was still a 20% rise in PM2.5 levels at the embassy.
• This further underscores the lack of a linear connection between stubble-burning and PM2.5 levels in Delhi-NCR. In August 2022, a network of 30 sensors was deployed across rural and urban areas of Punjab, Haryana, and Delhi.
• Data from these sensors aligned closely with those from the U.S. Embassy’s instrument. While stubble burning nearly ceases after November, the air quality index in Delhi-NCR has consistently been in the "very poor" to "severe" category from December to February since 2016, indicating that factors beyond stubble burning are significant contributors to air pollution.
• The authors note that the volume of biomass burned in Punjab and Haryana does not always correlate with the air quality in urbanized areas like Delhi-NCR, especially during peak rice-stubble burning months (October-November). 
• While there is some correlation between stubble burning and PM2.5 levels in Delhi-NCR when wind conditions are favorable, wind patterns alone do not explain PM2.5 levels.
• Other meteorological factors and local emissions play a significant role, as noted by Dr. Poonam Mangaraj from RIHN, Kyoto, Japan, the paper's first author. She explains that when dispersion conditions are unfavorable—such as low wind speeds or temperature inversions—pollutants may not disperse effectively, weakening or eliminating the correlation.
• Data from sensors recording PM2.5 and carbon monoxide (CO) show a persistent accumulation of fine particulate matter and CO in Delhi at night, suggesting local emissions as a significant factor.
• If stubble burning were the primary cause of air pollution in Delhi-NCR, CO levels would not increase at night. The study observed that day-night differences in PM2.5 levels in Delhi-NCR were about 20%, while CO concentration was about 67% higher at night in 2023 compared to the daytime, and 48% higher in 2022.
• In contrast, day-night variations were more distinct in Punjab and Haryana during intense stubble-burning periods.
• Therefore, the higher CO levels at night in Delhi-NCR suggest that sources other than stubble burning contribute significantly to air pollution

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

River interlinking, the fount of environmental disaster

For Preliminary Examination: Current events of national and international importance

For Mains Examination: GS III - Environment & ecology

Context:

On December 25, 2024, Prime Minister Narendra Modi laid the foundation stone for the Ken-Betwa River Link Project, which aims to solve the water scarcity in the Bundelkhand region that covers parts of Uttar Pradesh and Madhya Pradesh. The project also includes the construction of a dam located within the Panna Tiger Reserve, raising concerns about its submergence. Upon completion, this project will link the supposed water surplus Ken river with the Betwa in drought-stricken Bundelkhand — an area that had 58% forest cover in 1938

Read about:

Ken-Betwa River linking model

Panna Tiger reserve

Key Takeaways:

• This ₹45,000 crore project was initiated despite opposition from experts, including members of an empowered committee appointed by the Supreme Court of India, and bypassing laws that impose strict conditions on hydroelectric power projects. The idea of large-scale technological interventions to solve water-related challenges has gained traction. Politicians are increasingly promoting river interlinking as a geoengineering solution to India's ongoing water scarcity.
• The concept of inter-basin water transfer was first proposed 130 years ago by Sir Arthur Cotton, who designed irrigation dams in the Godavari and Krishna river valleys. This idea was later refined by M. Visvesvaraya, an early figure in Indian engineering, and further expanded by K.L. Rao and Captain Dinshaw J. Dastur in the 1970s and 1980s. Initially called the ‘National Water Grid’, the idea later evolved into the ‘River-Interlinking Project’ (ILR), which aims to transfer surplus water from the Ganga and Brahmaputra rivers to water-deficient regions in central and southern India.
• The National Water Development Agency (NWDA) was set up in 1982 to carry out surveys, investigations, and prepare feasibility reports for the National Perspective Plan. The NWDA identified 30 potential links for further study, divided into 14 Himalayan and 16 Peninsular river links. These links are expected to help mitigate floods and droughts, improve rural income, and address agricultural water scarcity.
• The project’s estimated cost of ₹5.5 lakh crore does not account for social, environmental, or operational expenses, and the burden of these costs will ultimately fall on the public. The idea of linking rivers to connect surplus rivers with water-deficient ones is flawed, as it ignores the massive environmental costs and the eventual destruction of rivers and delta ecosystems.
• Human-induced disruptions in natural hydrographic systems will devastate ecological niches, leading to severe consequences for long-term societal well-being, which will be a grave disservice to future generations.
• Additionally, the impacts of climate change on rainfall and river flows could worsen the situation. It remains unclear how the country’s commitment to mitigating climate change aligns with its plans to manipulate rivers.
• Policymakers fail to understand that there is no “free” surplus water in rivers. Simple calculations that suggest tapping water “lost to the sea” overlook the eco-hydrological realities of the issue. Proponents of these projects disregard the river as an integral part of the drainage basin, including the deltaic plains and its interaction with the sea.
• The ecosystem services provided by free-flowing rivers include the flushing of silt from riverbeds into coastal waters to form deltas. Floodwater is not simply ‘surplus’; it plays a crucial role in land fertility, groundwater recharge, and maintaining biodiversity, which sustains the livelihoods of millions of marginalized people.
• Diverting river water can starve deltaic regions of water, disrupting the balance of saltwater from the sea. This shift damages the delta ecosystem. The Indus Delta offers a poignant example. In her book Empires of the Indus: The Story of a River (2008), Alice Albinia describes how the Indus Delta, once the richest in Pakistan, was impoverished after the British constructed barrages, a practice continued by Pakistan after 1947.
• India has its own examples of such damage, with the downstream regions of the Narmada River suffering since the Sardar Sarovar dam was completed.
• Global examples of river channelization have also shown disastrous results. In Florida, the channelization of the Kissimmee River in 1954 to reduce flooding led to an environmental catastrophe, with the loss of wetlands, and significant resources are now being invested to restore its natural state. Similarly, the Aral Sea, once one of the largest lakes in the world, has become a desert after irrigation projects diverted the rivers that fed it, a legacy of the Soviet Union's geoengineering projects

The underlying causes of India’s water crisis

• India's water crisis is worsening, primarily due to ineffective water management, harmful environmental practices, unclear laws, and corruption. To address this, a national water policy should adopt an integrated approach to watershed management, with active involvement from local communities in monitoring the hydrological cycle.
• Collaboration with hydrologists, engineers, and biologists is necessary. The policy should prioritize effective aquifer management by regulating water consumption. Farmers must be involved in developing strategies for more efficient irrigation practices.
• The government has limited authority over wastewater management and should focus on creating innovative water reuse programs. Additionally, a thorough, interdisciplinary study of river basins is crucial before embarking on large-scale water transfer initiatives