Patna, March 21: The groundwater level in the state capital is dipping fast. Every year, it is depleting by 13cm. If the report of Central Ground Water Board, Mid-Eastern Region (CGWB-MER), is anything to go by, it will be down by a kilometre in 800 years.
A report titled “Assessment of groundwater in Patna urban area” published in October 2010 by CGWB-MER, Patna, said it was declining by 13cm per year. The water has gone deeper by 2.5m (7.5ft) over the past two decades, according to the report.
“The water-level in Patna can sustain the current and future water requirements. Water from adjoining areas gets used for extraction. The current decline is because of a large difference of rates at which water is getting extracted and at which shallow water (0.68m below ground-level to 10.78m below ground-level) is being revived by rain water,” a hydro-geologist at CGWB-MER said. Groundwater experts, though, are not ready to buy the “things under control” proclamation.
“Even if there is a decline of 13cm per year over the past two decades, which the board claims to get compensated by the water reserves, what do they have to say about the 60cm fall in the pre-monsoon levels between 2009 and 2010? Shallow water supplements only a fraction of water requirements of Patna,” said Ashok Ghosh, professor-in-charge, department of environment and water management, AN College, Patna.
According to a study, groundwater in Patna continues to be at 220m (660ft) below ground-level, constituting a total reserve of 1,500 million cubic metres. This fulfils requirement of over 90 per cent of the water requirement of the city.
This water is made available to the citizens either by Patna Municipal Corporation through 89 deep tubewells tapping the water in the range of 150-200m (250-600ft) or by household tubewells that extract water from a range of 40 to 100m (120ft to 300ft).
According to the estimate prescribed by Jawaharlal Nehru National Urban Renewal Mission, 2006, 52 per cent of population in Patna depend on the municipality for its water requirement, while 40 per cent of the households have their own tubewells. The total annual extraction is put at 180 million cubic metres.
“I had installed a jet motor pump through a deep borewell having a depth of 140ft below ground-level in 1986 but the force of water for filling my overhead tank declined after 2000. Earlier, it used to take 15-20 minutes to fill the tank, after 2005 it started taking 45 minutes to an hour. I replaced the pump with a submersible motor pump in 2008 and increased the depth of the well to 250ft below ground-level. Now the tank gets filled in 10-15 minutes,” said Suresh Kumar Sharma, a resident of Sri Krishna Nagar.
“Many older jet motors equipped with 100-150ft deep tubewell have stopped functioning because of lack of sufficient force. I have constructed hundreds of deep tubewells with a depth of over 250ft in the past three to four years, which are equipped with submersible pumps,” Jagannath Prasad, a private tubewell and motor pump installation contractor, said.