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New Delhi Air Potentially Chokes from Groundwater Conservation Policies in Adjoining Regions

Cite this: Environ. Sci. Technol. Lett. 2023, 10, 1, 3–5
Publication Date (Web):December 23, 2022
https://doi.org/10.1021/acs.estlett.2c00848

Copyright © Published 2022 by American Chemical Society. This publication is available under these Terms of Use.

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The TOC file published originally with this paper was changed. The new file published December 30, 2022.

In the postmonsoon (late fall/autumn) season of the past few years, unprecedented hazardous air quality has been prevailing across large parts of northern India, specifically in the Indian capital of New Delhi and the National Capital Region (NCR, population of 32 million). The outdoor air quality index (AQI) exceeded 500 (following U.S. Environmental Protection Agency 2018) across many parts of the NCR from the last week of October through the first two weeks of November 2022 (Figure 1a), suggesting residents are literally breathing smoke. Having industrial and vehicular emission-sourced fine particulate matter (PM2.5) concentrations exceeding 100 μg/m3 across the year, which increases to >500 μg/m3 during postmonsoon seasons, (1) the NCR is already known to be one of the most air-polluted cities in the world, where the World Health Organization (WHO) and National Ambient Air Quality standard (NAAQS) values for PM2.5 are set at 15 and 60 μg/m3, respectively, for 24 h. Regular inhalation of polluted air leads to chronic respiratory diseases and various other public health complications for a major portion of the citizens of the NCR. (2)

Figure 1

Figure 1. Photos of (a) air pollution-laden haze at India Gate (photographed in November 2022), receiving fume from (b) rice stubble burning in adjoining areas (photographed in Punjab state, November 2022), and (c) a groundwater-sourced irrigated rice paddy in India. (d) Plot of changes (centimeter per year) in GRACE-derived groundwater storage (GWS) trends in Punjab and Haryana state (combined) before (Sen’s slope of −6.23 cm/year) and after (Sen’s slope of −3.35 cm/year) groundwater conservation policy implementation periods (2009–2010).

Rice paddy stubble burning (PSB) in the NCR-adjoining western Indian states of Punjab and Haryana (Figure 1b) is estimated to contribute up to 70% of PM2.5 of the polluted NCR air during the postmonsoon period. (1) A daily average of ∼4000 agricultural field fires, mostly in fields with areas of <50 ha (leading to ∼23 million tons of stubble burning per year (3)), were witnessed in Punjab alone in the postmonsoon seasons of 2020–2022. Across south Asia, burning of leftover rice paddy stubble after harvest is an age-old practice for quick disposal of crop residue. (3) However, such PSB-sourced air pollution was not previously witnessed in the NCR even a few years ago (before 2010), leading to the intriguing question of its actual drivers. (4)

Punjab and Haryana states, located in the Indian parts of the Indo-Gangetic river basin, experience a semiarid hydro-climatic condition and are historically known for their prolific, less water-intensive crop (barley millet, wheat, etc.) production before the 1970s (pre-Green Revolution). By the mid-1990s, the combination of commercially lucrative high-yielding rice varieties (e.g., PUSA-44) and the availability of heavily subsidized electricity for the cheap pumping of groundwater for flood irrigation led to a rapid shift in the region’s agricultural practices to grow water-intensive rice paddy as a cash crop (e.g., basmati rice) (Figure 1c). Rice transplantations occur from late May to early June (premonsoon) with harvest in mid-October (end of the monsoon period). (1) However, the intense groundwater abstraction rates for flood irrigation led to the region experiencing one of the highest global groundwater depletion rates [Gravity Recovery and Climate Experiment (GRACE) derived 2003–2009 (Sen’s slope), −6.23 cm/year] by the early 2000s (5) (Figure 1d). Well-intended groundwater conservation policies were enacted in 2009 (Punjab/Harayana Preservation of Subsoil Water Act, 2009), mandating a delay of rice transplantation to mid−late June (∼15–20) to coincide with the advent of monsoon rains (with harvest from the end of October to early November (1,2)), in an attempt to reduce irrigation abstraction requirements and enable greater groundwater storage replenishment.

This shift in transplantation and harvest timing left only a shortened time window between kharif paddy harvesting and winter paddy plantation from the middle to end of November. In addition, introduction of mechanized harvesters led to more stubble on the ground. This compelled the farmers to practice widespread stubble burning in early November (∼86%) for the quick and easy disposal of crop residue. (1) Unfortunately, this short window also coincides with the change of seasons over northern India in early November, (3,4) with a resulting decrease in air temperature (impeding hydroclimatic dispersion) and weakening of southwest monsoon winds. This leads to the advent of northern winds that channel from northwestern India and funnel through the low-altitude, northern Indian plains toward the Bay of Bengal, thereby transporting the PSB fumes eastward toward the densely populated NCR and other parts of northern India (population of >700 million). Furthermore, and contrary to recent government policies, irrigated cultivation has continued to grow unabated since 2009 (>10%) due to the exponentially increasing demand for these crops. This has led to not only a continued decline in groundwater storage, albeit at a lower rate [2010–2017 (Sen’s slope), −3.35 cm/year] (Figure 1d) but also an increased crop cultivation area and contributions to stubble burning. (5)

The shift in cultivation timing combined with the practice of stubble burning and socioeconomic pressures versus seasonal hydro-climatic patterns has resulted in PSB fumes engulfing northern India and a hazardous deterioration of air quality in the NCR and other parts of northern India. This unique nexus is severely impacting the public health of the NCR, with pervasive human respiratory distress, ∼16 000 annual untimely deaths, and an estimated reduction of life expectancy by 6 years at a potential annual economic cost of US $30 billion. (1,3) India records an annual ∼1.8 million deaths from air pollution-related health impacts. (1)

Recent legislative acts enforcing the prohibition of PSB have been ineffective, with widespread burning of stubble still continuing, as farmers have limited options for the quick and efficient disposal of crop residue within a short time frame. (2) Coupled with continued state subsidies for cheaper electricity and guaranteed market prices, enhanced rice production is set to continue, and thus, alternative mitigation strategies are urgently needed. Ideas include agronomic technologies such as motorized harvesters and automated seeders that result in decreased crop residue; in-field or industrial treatments like biocomposting, biochar, or biodistillation; recycling stubble straw for paper, fodder, or fertilizer; encouraging the shorter-duration growing or long-lived perennial rice paddy varieties, incentivizing the cultivation of less water intense crops as well as rotation with vegetables; the revival of the traditional cultivation of wheat, barley, and millet; discouraging irrigation abstraction through withdrawal of subsidized electricity; and developing a comprehensive framework to ease the cultivation cycle without causing any further environmental calamity.

The prevailing situation creates a unique vicious cycle. It highlights an unexpected consequence of well-intended policy decisions and the socioeconomic trade-offs of food production versus environmental protection and public health. It also illustrates the increasing importance of systems-based approaches to conserve natural resources and protect public health across the globe.

Author Information

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  • Corresponding Authors
  • Authors
    • Kirpa Ram - Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi221005, IndiaOrcidhttps://orcid.org/0000-0003-1147-4634
    • Dipankar Saha - Central Ground Water Board, Ministry of Jal Shakti, Government of India (former), Faridabad121001, India
  • Author Contributions

    A.M. authored the manuscript with input from S.N.T., K.R., and D.S.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The authors are grateful for support received from Subroto Vyas for groundwater storage trend quantification and Prafulla Sahoo for the photograph (Figure 1b). Groundwater storage data were obtained from GRACE mission of NASA JPL. A.M. acknowledges part of the work was supported by a sponsored research project by the Government of India, Department of Science and Technology [DST/TMD-EWO/WTI/2K19/EWFH/2019/201 (G) & (C) dated 28.10.2020]. S.N.T. acknowledges funding received from “Open Philanthropy” under the new centre of excellence (CoE)/Advanced Technologies for Monitoring Air-quality iNdicators (Atman) approved by office of Principal Scientific advisor (PSA) to the Government of India.

References

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This article references 5 other publications.

  1. 1
    Balwinder-Singh; McDonald, A. J.; Srivastava, A. K.; Gerard, B. Tradeoffs between groundwater conservation and air pollution from agricultural fires in northwest India. Nature Sustainability 2019, 2 (7), 580583,  DOI: 10.1038/s41893-019-0304-4
  2. 2
    Sembhi, H.; Wooster, M.; Zhang, T.; Sharma, S.; Singh, N.; Agarwal, S.; Boesch, H.; Gupta, S.; Misra, A.; Tripathi, S. N.; Mor, S.; Khaiwal, R. Post-monsoon air quality degradation across Northern India: assessing the impact of policy-related shifts in timing and amount of crop residue burnt. Environ. Res. Lett. 2020, 15 (10), 104067,  DOI: 10.1088/1748-9326/aba714
  3. 3
    Kant, Y.; Chauhan, P.; Natwariya, A.; Kannaujiya, S.; Mitra, D. Long term influence of groundwater preservation policy on stubble burning and air pollution over North-West India. Sci. Rep. 2022, 12 (1), 2090,  DOI: 10.1038/s41598-022-06043-8
  4. 4
    Saha, D.; Chakraborty, M.; Chowdhury, A. Stubble burning in northwestern India: Is it related to groundwater overexploitation? In Groundwater for Sustainable Livelihoods and Equitable Growth; CRC Press: Boca Raton, FL, 2022; pp 123134.
  5. 5
    Bhanja, S. N.; Mukherjee, A. In situ and satellite-based estimates of usable groundwater storage across India: Implications for drinking water supply and food security. Advances in Water Resources 2019, 126, 1523,  DOI: 10.1016/j.advwatres.2019.02.001

Cited By

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This article is cited by 2 publications.

  1. Arindam Roy, Prasenjit Acharya. Energy inequality and air pollution nexus in India. Science of The Total Environment 2023, 876 , 162805. https://doi.org/10.1016/j.scitotenv.2023.162805
  2. Sarath K. Guttikunda, Sai Krishna Dammalapati, Gautam Pradhan, Bhargav Krishna, Hiren T. Jethva, Puja Jawahar. What Is Polluting Delhi’s Air? A Review from 1990 to 2022. Sustainability 2023, 15 (5) , 4209. https://doi.org/10.3390/su15054209
  • Abstract

    Figure 1

    Figure 1. Photos of (a) air pollution-laden haze at India Gate (photographed in November 2022), receiving fume from (b) rice stubble burning in adjoining areas (photographed in Punjab state, November 2022), and (c) a groundwater-sourced irrigated rice paddy in India. (d) Plot of changes (centimeter per year) in GRACE-derived groundwater storage (GWS) trends in Punjab and Haryana state (combined) before (Sen’s slope of −6.23 cm/year) and after (Sen’s slope of −3.35 cm/year) groundwater conservation policy implementation periods (2009–2010).

  • References

    ARTICLE SECTIONS
    Jump To

    This article references 5 other publications.

    1. 1
      Balwinder-Singh; McDonald, A. J.; Srivastava, A. K.; Gerard, B. Tradeoffs between groundwater conservation and air pollution from agricultural fires in northwest India. Nature Sustainability 2019, 2 (7), 580583,  DOI: 10.1038/s41893-019-0304-4
    2. 2
      Sembhi, H.; Wooster, M.; Zhang, T.; Sharma, S.; Singh, N.; Agarwal, S.; Boesch, H.; Gupta, S.; Misra, A.; Tripathi, S. N.; Mor, S.; Khaiwal, R. Post-monsoon air quality degradation across Northern India: assessing the impact of policy-related shifts in timing and amount of crop residue burnt. Environ. Res. Lett. 2020, 15 (10), 104067,  DOI: 10.1088/1748-9326/aba714
    3. 3
      Kant, Y.; Chauhan, P.; Natwariya, A.; Kannaujiya, S.; Mitra, D. Long term influence of groundwater preservation policy on stubble burning and air pollution over North-West India. Sci. Rep. 2022, 12 (1), 2090,  DOI: 10.1038/s41598-022-06043-8
    4. 4
      Saha, D.; Chakraborty, M.; Chowdhury, A. Stubble burning in northwestern India: Is it related to groundwater overexploitation? In Groundwater for Sustainable Livelihoods and Equitable Growth; CRC Press: Boca Raton, FL, 2022; pp 123134.
    5. 5
      Bhanja, S. N.; Mukherjee, A. In situ and satellite-based estimates of usable groundwater storage across India: Implications for drinking water supply and food security. Advances in Water Resources 2019, 126, 1523,  DOI: 10.1016/j.advwatres.2019.02.001

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