Kolkata, April 19 (IANS): Have you heard of water export? Apparently, India has been sending "virtual" water to other countries through its food exports, and this trend is likely to continue.

"Water used in agriculture is recirculated, but the (virtual) water exported out when we export food is not recoverable. Over a period of time, if food export is extensive, the country's water reserves go down affecting water sustainability," says Prashant Goswami, a researcher at the CSIR Fourth Paradigm Institute, Bengaluru.

In answers send by email and given on the phone, Goswami, a Shanti Swarup Bhatnagar awardee, says that in contrast, China is a net importer of food and is therefore amplifying its water reserves. He suggests a change in India's food policy.

Goswami, a climate and atmospheric modelling expert, warns in a study that if the current rate of net export of water in end products continues, India will lose its "entire available water in less than 1,000 years."

This projection may go down further if parameters like increase in food demand and reduction in surface water due to climate change are taken into consideration, according to the study.

The findings of the study 'Virtual water trade and time scales for loss of water sustainability: A comparative regional analysis' were published in the March 20 edition of Nature Scientific Reports.

India, the US, and China are known to be the world's leading virtual water users and in the wake of growing consumption, such water trade plays a key role in the water sustainability of a nation, the study's author Goswami said.

Goswami also said that for several decades, China has maintained a positive trade balance (more import than export) in virtual water trade and it is supplementing its water reserves.

The study says India's water import through food grains is virtually nil. From an import-intensive paradigm during 1960-70, India had moved to an export-intensive regime in virtual water trade, it says.

Stressing that a sustainable food or agricultural policy must be based on zero trade deficit or positive trade balance in virtual water, Goswami said that as water demand in other sectors like manufacturing, services and construction increases, this will put additional pressure on water sustainability in India.