Changing rainfall patterns linked to water security in India

January 10, 2017, International Institute for Applied Systems Analysis
Changing precipitation in India 1980-2013. Credit: Asoka A, 2017

Changing rainfall is the key factor driving changes in groundwater storage in India, according to a new study led by the Indian Institute of Technology (IIT) Gandhinagar published in the journal Nature Geoscience. The study shows that changing monsoon patterns—which are tied to higher temperatures in the Indian Ocean—are an even greater driver of change in groundwater storage than the pumping of groundwater for agriculture.

Agriculture in India relies heavily on groundwater for irrigation, particularly in the dry northern regions where precipitation is scarce. Groundwater withdrawals in the country have increased over tenfold since the 1950's, from 10-20 cubic kilometers per year in 1950, to 240-260 cubic kilometers per year in 2009. And satellite measurements have shown major declines in groundwater storage in some parts of the country, particularly in northern India.

"Groundwater plays a vital role in food and water security in India. Sustainable use of groundwater resources for irrigation is the key for future food grain production," says study leader Vimal Mishra, of the IIT Gandhinagar. "And with a fast-growing population, managing groundwater sustainably is going become even more important. The linkage between monsoon rainfall and groundwater can suggest ways to enhance in India and especially in the regions where rainfall has been declining, such as the Indo-Gangetic Plain."

Groundwater acts like a bank for water storage, receiving deposits from surface water and precipitation, and withdrawals as people pump out water for drinking, industry, and irrigating fields. If withdrawals add up to more than the deposits, eventually the accounts could run dry, which could have disastrous consequences.

"This study adds another dimension to the existing water management framework. We need to consider not just the withdrawals, but also the deposits in the system," says Yoshihide Wada, a study coauthor and the deputy director of the Water program at the International Institute for Applied Systems Analysis (IIASA) in Austria.

The issue of has been a topic of much discussion in India, but most planning has focused on pumping, or the demand side, rather than the deposit side. By looking at water levels in wells around the country, the researchers could track groundwater replenishment following the monsoons. They found that in fact, variability in the monsoons is the key factor driving the changing storage levels across the country, even as withdrawals increase.

In addition, the researchers found that the monsoon precipitation is correlated with Indian Ocean temperature, a finding which could potentially help to improve precipitation forecasts and aid in water resource planning.

"Weather is uncertain by nature, and the impacts of climate change are extremely difficult to predict at a regional level," says Wada "But our research suggests that we must focus more attention on this side of the equation if we want to sustainably manage water resources for the future."

Explore further: Anthropogenic groundwater extraction impacts climate

More information: Akarsh Asoka et al, Relative contribution of monsoon precipitation and pumping to changes in groundwater storage in India, Nature Geoscience (2017). DOI: 10.1038/ngeo2869

Related Stories

Anthropogenic groundwater extraction impacts climate

January 10, 2017

Anthropogenic groundwater exploitation changes soil moisture and land-atmosphere water and energy fluxes, and essentially affects the ecohydrological processes and the climate system. In over-exploited regions, terrestrial ...

Tropical groundwater resources resilient to climate change

December 11, 2015

Tropical groundwater may prove to be a climate-resilient source of freshwater in the tropics as intense rainfall favours the replenishment of these resources, according to a new study published in Environmental Research Letters.

Recommended for you

How the Elwha dam removals changed the river's mouth

January 19, 2018

For decades, resource managers agreed that removing the two dams on the Elwha River would be a big win for the watershed as a whole and, in particular, for its anadromous trout and salmon. The dams sat on the river for more ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.