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The depletion of groundwater in India may triple by the middle of the 21st century.

A groundwater well in Gujarat, India

In many regions, warm weather leads to a higher need for freshwater, especially in agriculture. As temperatures rise, crops may experience heat stress and lose more water through evapotranspiration, resulting in a greater demand for water to support their growth and yield.

Rising temperatures caused by climate change will result in a greater need for irrigation, potentially leading to an increase in groundwater extraction.

A recent study published in Science Advances reveals that the depletion of groundwater in India is projected to triple by the middle of this century, mainly due to crop irrigation. This poses a significant challenge for managing groundwater levels.

In summary, according to Vimal Mishra, a civil engineer at the Indian Institute of Technology Gandhinagar who was not involved in the study, climate warming will result in greater irrigation needs and subsequently, more extraction of groundwater.

Shrinking Buffer

According to Nishan Bhattarai, a geographer from the University of Oklahoma and the main researcher of the study, groundwater serves as a buffer in the face of climate change by supplying water to alleviate heat stress in crops. The goal of the study was to comprehend the connection between groundwater levels, crop water stress, and climate change.

Bhattarai and his team studied the current methods used by farmers to increase irrigation in response to rising temperatures, in order to make predictions on how they will continue to adapt as temperatures continue to increase in the future. Their analysis involved examining records of groundwater levels in wells throughout India, using remote sensing data to assess crop stress, and reviewing weather records to track changes in precipitation and temperature.

By combining the three sets of data, researchers discovered that as temperatures increased, groundwater levels decreased and crops experienced more strain. The only deviation from this pattern was during the summer monsoon season, where heavy rainfall potentially aided crop growth. However, the findings also revealed that rising temperatures led to decreased groundwater recharge during both the monsoon and dry seasons due to increased evapotranspiration rates.

According to Mishra, as temperatures increase, climate change is predicted to intensify the summer monsoon. While this could potentially reduce groundwater depletion, the deeper aquifers used for irrigation take longer to replenish compared to the shallower ones, which are mainly used for residential and small-scale agricultural purposes that can be replenished by monsoon rains.

Using a variety of climate models, the scientists predicted the potential demand for groundwater in the future by considering the effects of higher temperatures and greater monsoon rainfall. They concluded that if there is a 1°C increase in temperature, the depletion rate of groundwater in India from 2041-2080 could potentially reach 36 centimeters per year, which is more than three times the current rate.

Limits to Adaptation

Bhattarai and his team emphasized the importance of implementing policies and taking action to protect groundwater in response to the threats posed by climate change on water security.

“Due to changing rainfall patterns, groundwater irrigation, our primary method of coping, will soon become unfeasible in numerous regions of India.”

According to Aditi Mukherji, the director at Climate Change Adaptation and Mitigation Impact Action Platform at CGIAR, groundwater irrigation has been our primary method of adjusting to changes in rainfall. However, in many areas of India, where overuse of groundwater is already an issue, this may no longer be a viable option. She believes that the key finding of the study is that agriculture must decrease its dependence on groundwater irrigation by cultivating crops that require less water.

However, other experts in the field of climate science cautioned against drawing definitive conclusions from the findings.

According to Thiagarajan Jayaraman, a climate policy researcher at the M. S. Swaminathan Research Foundation in India, there are numerous uncertainties regarding the future distribution of rainfall and the impact of non-climatic factors on the current rate of groundwater depletion.

Bhattarai admitted that he and his colleagues did not consider nonclimate factors, such as alterations in crop types or farming methods, due to a lack of specific information on these factors.

The speaker acknowledged that there is a significant amount of uncertainty about the future and also recognized that there are limitations in forecasting.

Mishra stated that further efforts are required to investigate the impact of climate change and human actions on groundwater storage in India, using varying approaches to gain a deeper understanding.

“I am a Science Writer named Rishika Pardikar, also known as @rishpardikar on social media.”

According to Pardikar (2023), the rate of groundwater depletion in India may triple by the middle of the century. This information was published in Eos on October 24, 2023, with a DOI of 10.1029/2023EO230404.

Text © 2023. The authors. CC BY-NC-ND 3.0

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