Decline in Usable Groundwater

• 11 Apr 2019

A team from the Indian Institute of Technology (IIT) Kharagpur, West Bengal and Athabasca University, Canada, has compiled the first estimates of Usable Groundwater Storage (UGWS) at the state-level across India using both in situ and satellite-based measurements.

• For the compilation, the groundwater-level data was used from 3,907 in situ monitoring wells across the country.
• The compilation includes total UGWS estimation between the years 2005 and 2013.
• Till now, the government agencies have been able to estimate the total groundwater, not the UGWS.
• India is the largest user of groundwater in the world. It uses an estimated 230 km³ of groundwater per year - over a quarter of the global total.

Key Findings

• More than 85 % of the groundwater usage in India is linked with irrigation abstraction practices.
• The estimates show rapid depletion of usable groundwater storage during 2005-2013 in most of the northern parts of the country, which lost 8.5 km³ / year of the total groundwater, and the eastern parts which lost 5 km³ /year of the total groundwater.
• Rapid depletion of UGWS in Assam, Punjab, Haryana, Uttar Pradesh, Bihar, and West Bengal.
  • A northeastern state like Assam which has always been regarded as a water-affluent; lost 2 % of its usable groundwater resource and is at the brink of suffering drought and famine in impending years.
  • Haryana, which gets an annual precipitation of 689 mm, had the highest level of usable groundwater with 3,593 cm while Himachal Pradesh with a precipitation of 1,147 mm per year had the lowest UGWS level of 520 cm.
  • Some pockets in Uttar Pradesh also saw a dip in groundwater table.
  • In these areas, increase in agricultural production has been at the cost of non-renewable loss in the groundwater volume.
• Reasons cited
  • Lack of an organised water supply leads to increased dependence on groundwater.
  • Depletion in groundwater is positively linked with the increased cropping practice of water intensive crops.
  • Overexploitation of the groundwater: About 85 %of rural drinking water needs and 65 %of irrigation needs and 50 %of urban drinking water and industrial needs are fulfilled from the ground water.
• Consequences
  • Rapid depletion in UGWS would accelerate the decline in food production and availability of drinking water, two of the prime goals under UN Sustainable Development Goals 2030. This would affect more than 120 million people in the Gangetic states.
  • Summer groundwater droughts that some states are facing; would intensify in recent future years, will become severe to very severe by 2050, with the possibility of spreading over all the seasons.
  • Decline in the flow in the adjoining rivers, including Ganga, thus also impacting river-aquifer interaction.
• Suggestions
  • In order to develop a sustainable groundwater management programme, it is important to know the exact water-stress.
  • India needs to develop a much robust quantitative approach, possibly with the help of advanced hydroscience and data science techniques to understand the conjunctive water demands and usages.
• The southern and western Indian states like Andhra Pradesh, Maharashtra, Gujarat, Chattisgarh have shown replenishing usable groundwater storage trends.