The UN World Water Development Report 2015 has raised concerns among experts in Bihar over water scarcity issues affecting the state over the next few decades.

The report, released on March 20, two days ahead of World Water Day, has stated that the demand for water across the globe is set to increase by 55 per cent over the next 15 years, which would meet the water need of the world only up to 60 per cent by 2030.

India, on the other hand, would be among the top five countries facing severe water scarcity over the next few years. Experts working in the field of water conservation have claimed that despite being rich in surface water, there is immense pressure on groundwater table in Bihar.

"At a time when the groundwater is depleting drastically across the globe, Bihar too is not an exception to this issue. There is severe over-exploitation of groundwater in the state despite abundance of surface water. Based on current trend in water demand and population growth in the state, Bihar might also face serious groundwater scarcity over the next 15-20 years, if measures are not taken to keep a tab on its over-exploitation," said Ashok Ghosh, member and chairman of State Level Expert Appraisal Committee, the technical committee of State Environment Impact Assessment Authority.

The UN report has stated that groundwater supplies are diminishing with an estimated 20 per cent of the world's aquifers currently over-exploited. "The recharge of groundwater has also reduced sharply due to fast rate of urbanisation. Thus, it is required that scientists should come up with innovative ways for construction of percolation tanks, check dams and reservoirs in water-scarce regions for meeting the requirements of the people through surface water," said Ghosh, who is also professor-in-charge at department of environment and water management, AN College.

Pradhan Parthasarathy, a professor at Central University of Bihar (CUB), claimed that erratic rainfall distribution is also one of the major factors behind sharp depletion of groundwater resources. "If the rainfall is erratic, especially in context of its reduced recharge due to increased urbanisation, then there would be minimal recharge of the aquifers. Thus, we need to study the pattern of rainfall as well to exactly assess the impact on the ground- water resources," he said.

Regarding erratic rainfall affecting groundwater resources, sources have claimed that the deficient rainfall in the monsoon in Bihar over the past three years might have led to adverse impact on the natural recharge of the groundwater table of the state.

With regard to Patna, recent studies have stated that 52 per cent of the population of the city at present is dependent on municipal water supply and the remaining 48 per cent are dependent on private sources such tubewells and borewells.

Over-exploitation of groundwater apart, experts also raised concern over depleting surface water resources. A research report by Parthasarathy stated that based on the analysis during the period of 1901-2002, the districts south of the Ganga have shown a sharp decline in surface water between 1981-90 and 1991-2000.