National Compilation on Dynamic Ground Water Resources of India, 2017

The total annual groundwater recharge (the recharge during monsoon and non-monsoon seasons) is stated to be 431.86 bcm (billion cubic meters). After accounting for natural discharge, the annual groundwater resources that can be successfully extracted is 392.7 bcm.

As of March 2017, the annual groundwater extraction in the country is stated to be 248.69 bcm.

The average annual rainfall in India is around 119 cm, the 2017 report says. Three-fourth of this rainfall is received between the months of June and September. The main source of replenishable groundwater is rainfall, which contributes to nearly 67 per cent of the total annual groundwater recharge. Taken together, other sources of groundwater – such as canal seepage, return flow from irrigation, recharge from tanks, ponds and water conservation structures –account for 33 per cent of the total annual groundwater recharge.

Rainfall during the monsoon season forms over 70 per cent of the total annual groundwater recharge in the states and union territories of Assam, Goa, Gujarat, Jharkhand, Madhya Pradesh, Meghalaya, Mizoram, Nagaland, Rajasthan, Sikkim, Andaman and Nicobar, Dadra and Nagar Haveli, Daman and Diu, and Lakshadweep.

The report categorises assessment units into four categories depending on the level of groundwater extracted from them: ‘safe’, ‘semi critical’, ‘critical’, and ‘over-exploited’. It states that units flagged as ‘over-exploited’ demand urgent change in extraction patterns and interventions through surface water.

Out of the 6,881 units assessed in the report, 4,310 units were categorised as ‘safe’, where less than 70 per cent of the groundwater has been extracted.

The report states that 972 assessment units are in the 'semi-critical’ stage with 70-90 per cent of groundwater already extracted.

About 310 assessment units have been deemed ‘critical’ in the report where the stage of groundwater extraction is between 90 and 100 per cent.

As many as 1,186 assessment units were categorised as ‘over-exploited’, meaning that the groundwater extracted from them annually exceeded the amount that can be replenished. The report notes that over 17 per cent of the units assessed across the country are ‘over-exploited’.

The western part of the country – especially regions in Rajasthan and Gujarat – are characterised by arid climate conditions, leading to a reduction in the amount of groundwater that can be recharged naturally. This, the report notes, has worsened groundwater levels.

More than 25 per cent of the total units assessed in Delhi, Haryana, Himachal Pradesh, Karnataka, Puducherry, Punjab, Rajasthan and Tamil Nadu, were either in the ‘over-exploited’ or ‘critical’ stage of extraction.

Focus and Factoids by Archana Shukla.