GROUNDWATER
1. Context
The excessive extraction of groundwater for drinking and irrigation has shifted the Earth’s axis of rotation, according to a new study. Noting that humans pumped out around 2,150 gigatons of groundwater between 1993 and 2010, the study says that the planet’s axis has drifted at the rate of 4.36 cm per year towards the east.
2. Groundwater Extraction in India
- Groundwater extraction in India is a significant issue due to the high dependence on groundwater for agriculture, industry, and domestic purposes.
- India is the largest user of groundwater globally, accounting for about 25% of the total global groundwater extraction.
- Excessive groundwater pumping has led to a decline in water tables in many parts of the country, causing issues like water scarcity and depletion of aquifers.
- Agriculture accounts for the majority of groundwater usage in India, with farmers relying on tube wells and bore wells for irrigation.
- Rapid urbanization and industrialization have also contributed to increased groundwater extraction.
- Unregulated and unsustainable groundwater extraction practices have resulted in the depletion of groundwater resources and the intrusion of saline water in coastal areas.
- The government has implemented measures to regulate groundwater usage, such as promoting rainwater harvesting, encouraging efficient irrigation practices, and implementing groundwater management plans.
- The Central Ground Water Authority (CGWA) monitors and regulates groundwater extraction in over-exploited areas.
- Sustainable management of groundwater resources is crucial for ensuring long-term water security in India.
3. Polar Motion and Shifting Axis
- Earth's axis and poles naturally shift due to changes in mass distribution, known as "polar motion."
- Rocks circulating in Earth's mantle and other factors cause the planet's mass to shift, leading to a change in the position of the rotational axis.
- The shift of the axis can vary by several meters in a year, according to recent research.
- Human activities, including climate change, also impact polar motion.
- Climate-driven changes in water mass distribution, such as melting glaciers and ice in Greenland, can cause the axis to drift.
- Studies have shown that climate change has been causing the rotational axis to shift more than usual since the 1990s.
4. Factors Affecting Earth's Axis
- Researchers, led by Ki-Weon Seo, used 17 years of observational data and a computer model to investigate the factors influencing Earth's rotation of the axis.
- Initially, their predictions did not match the observed level of shift in previous years.
- The team considered various data, including atmospheric pressure, ocean bottom pressure, reservoirs, polar ice, glaciers, wind, currents, and groundwater.
- When groundwater effects were included, the estimated spin axis variations aligned well with observations.
- The study found that the redistribution of groundwater had the largest impact on the drift of the rotational pole.
- Groundwater extraction in North America and northwestern India, located at Earth's mid-latitudes, significantly influenced polar motion compared to extraction at the poles or equator.
5. Impact of Groundwater Extraction
- Ki-Weon Seo explained that mass changes at the equator or poles do not affect the rotational pole; instead, the rotational pole change is linked to the moment of inertia of the Earth, which is sensitive to midlatitude mass change.
- Groundwater extraction for irrigation and freshwater demands plays a significant role.
- Seo and his team confirmed that groundwater extraction contributes to global sea level rise.
- Their calculations aligned with previous research, which estimated that groundwater extraction raised global sea levels by 6.24mm between 1993 and 2010.
- The water extracted from the ground eventually finds its way into the oceans, impacting sea levels.
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For Prelims: Groundwater extraction, Central Ground Water Authority (CGWA), Rapid urbanization, Polar motion, Earth's axis, Global sea level.
For Mains: 1. Discuss the challenges and consequences of groundwater extraction in India. What are the key factors contributing to excessive groundwater pumping, and how does it impact water security and sustainability? (250 words).
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Previous Year Questions1. With reference to the water on the planet Earth, consider the following statements : (UPSC 2021)
1. The amount of water in the rivers and lakes is more than the amount of groundwater.
2. The amount of water in polar ice caps and glaciers is more than the amount of groundwater.
Which of the statements given above is/are correct?
A. 1 only
B. 2 only
C. Both 1 and 2
D. Neither 1 nor 2
Answer: B
2. Consider the following statements: (UPSC 2020)
1. 36% of India's districts are classified as "overexploited" or "critical" by the Central Ground Water Authority (CGWA).
2. CGWA was formed under the Environment (Protection) Act.
3. India has the largest area under groundwater irrigation in the world.
Which of the statements given above is/are correct?
A. 1 only
B. 2 and 3 only
C. 2 only
D. 1 and 3 only
3. Consider the following statements:
1. On the planet Earth, the freshwater available for use amounts to less than 1% of the total water found.
2. Of the total freshwater found on the planet Earth 95% is bound up in polar ice caps and glaciers.
Which of the statements given above is/are correct?
A. 1 only
B. 2 only
C. Both 1 and 2
D. Neither 1 nor 2
Answer: A
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Source: The Indian Express
