The Jal Shakti Ministry is working on an ambitious plan to deploy a vast network of groundwater sensors that will continuously relay information on groundwater levels as well as the degree of contamination down to the taluk level. Currently, such information is only measured a handful of times a year and communicated via reports of the Central Groundwater Board.
Establishing a network that will continuously measure groundwater quality, feed it into a centralised network such as that of the National Water Informatics Centre (NWIC) and available for monitoring would make groundwater visible much the same way as air quality, meteorological variables –air pressure, moisture, precipitation – is now, Subodh Yadav, Joint Secretary, Department of Water Resources told The Hindu.
“We can potentially provide groundwater forecasts to farmers that would be useful for sowing, and updated advisories that can influence groundwater extraction policies by States,” he added. “Except for information on water flow governed by international treaties, most of this information will be publicly accessible.”
67,000 recordable units in the future
The Central Groundwater Board currently relies on a network of about 26 thousand groundwater observation wells that require technicians to manually measure the state of groundwater in a region.
Under the new initiative, around 16,000-17,000 digital water level recorders will be connected to piezometers in the wells. Piezometers measure groundwater levels, the recorders will transmit the information digitally.
In the next three years, the CGWB aims to increase its network from the existing 26,000 to about 40,000. When combined with similar networks possessed by other institutions – State bodies, agriculture and meteorology departments – India will have about 67,000 digitally recordable units to monitor groundwater dynamics.
“This is a continuous process and we will have to keep increasing our monitoring for better higher resolution data,” said Mr. Yadav.
ALSO READ | Level of groundwater extraction lowest in 18 years, finds study
The CGWB is in charge of the National Aquifer Mapping Program (NAQUIM), that as of March has mapped the country’s aquifers at a resolution of 1:50000 and – under the second phase of the programme – expects to improve the resolution by five times in the country. So far, an area of 25.15 lakh square km has been covered under the NAQUIM studies.
Nitrate contamination in some regions
In the latest Ground Water Resource Assessment-2022, the total annual groundwater recharge in the country has been assessed as 437.60 billion cubic metres (BCM). The annual extractable groundwater resource has been assessed as 398.08 bcm, with actual extraction of 239.16 bcm.
The average stage of groundwater extraction for the country as a whole works out to be about 60.08%. Anything above 70% is considered “critical” though there are regions in Punjab, Haryana, Delhi and Rajasthan with groundwater blocks with over 100% extraction.
Reports over the years suggest that 85% of rural India uses groundwater for drinking and domestic purposes. In cities with a population of over 10 lakh, about 40% have seen water levels in monitored wells either stay stable or drop.
Groundwater contamination, the CGWB says, is mostly “geogenic” (natural) and hasn’t significantly changed over the years. However, nitrate contamination – a result of the use of nitrogenous fertilisers—has been observed. Sections of nearly 409 districts have been confirmed with fluoride contamination and parts of 209 districts have noted arsenic contamination.
Those regions and States that are known to have groundwater contamination, for instance, coastal salinity or excessive depletion, will be monitored more intensely for action by States, said Mr. Yadav.
Published - April 23, 2023 12:43 pm IST
