Its extraction has increased by 5.08 per cent in the past two years
By Suryash Kumar
Groundwater in Kolar, Chikkaballapur, Bengaluru Rural and Bengaluru Urban districts is overexploited, says a study by the Central Ground Water Board.
According to the National Compilation on Dynamic Groundwater Resources of India by the Central Ground Water Board, out of the 234 assessment units (taluks) in Karnataka, 49 (20.94%) are overexploited. Groundwater extraction has increased from 64.85% in 2020 to 69.93 % in 2022.
Jagadeshwari, a geologist at Groundwater Directorate and Karnataka Groundwater Authority, informed The Observer: “In overexploited districts, restriction on drilling borewells and separate permission to extract water before drilling borewells is required…. Overexploited category falls into the 100% and above category. This means more groundwater is extracted than replenished.”
Commercial and residential users need permission to dig new borewells in overexploited areas. Commercial users consume over 2,000 KLD (kilolitres/day), and domestic users consume up to 1,000 KLD. Any commercial user of groundwater needs a no-objection certificate and is permitted to withdraw 50% of the groundwater capacity, she added.
“Groundwater is evaluated twice a year, and water from static wells is used for evaluation. Static wells refer to wells in which water is not disturbed by exploitation. The Groundwater Directorate collects water samples before and after the monsoon.”
About 30 percent of Karnataka’s groundwater has been overexploited.The overdraft is estimated to be about 0.22millionhectare meters, according to a research article in the journal Groundwater Regulation and Management Practices in Karnataka.
Rajendranan, a retired geologist, said overexploitation happens when people tap more water, and the water table is not recharged. “The salt content is high if water is not recharged. And the deeper we go, the salinity increases. Some parts of the city groundwater are overexploited, and some are underexploited…. Borewell utilization is less, but in outer areas, there is overdependence on borewells.”
In Karnataka, the quality of groundwater is a major concern as people have been falling ill after drinking contaminated water.
Apeksha, a consultant at the state rural drinking water supply and sanitation department, informed The Observer: “Under WQMSP (Water Quality Management and Surveillance Program), the rural department collects samples and conducts sanitary surveys to monitor water quality. Water- treatment plants are established to treat water in villages before it can be supplied, and if the water source has a high concentration of harmful substances, the water source is marked red to indicate it is not portable.
“We have an awareness program for people to make them aware of contaminated water sources. The government is trying to establish a full-fledged microbiological lab in every district, and in a few taluks of Hassan/Mysore, the lab is 90% complete.”
The government has 32 district laboratories and 48 sub-district laboratories. A safe water network suggests technology that can be used for purification. The technology requires investment and maintenance.
“Right now, the laboratories can only test the absence or presence of bacteria, but once full-fledged laboratories are set up, we can tell what kind of bacteria is present. What the rural department suggests is to boil your water before drinking.”
Overexploitation of groundwater can be prevented if the government build infrastructure for tapping rainwater to recharge groundwater. Further, changing the cropping pattern can pare groundwater usage significantly.
Karnataka’s Water Policy 2022 says groundwater extraction other than for domestic use should be restricted for commercial use depending on the degree and zone of exploitation.
