As winter tips into summer, the next round of water struggles will begin. By February, hand pumps across rural India will start going dry. People in urban centres, mostly small towns living off small stores of groundwater, will start getting increasingly erratic supply. The government will once again initiate its knee-jerk crisis management – tanker supplies.
The NITI Aayog had pointed out that several Indian cities will start running out of groundwater by 2020. That is also true of large parts of rural India where the trek for water lengthens each summer.
The Central Ground Water Board (CGWB) data shows a rapid fall in water tables over the past decade. Droughts from 2014 to 2017 as well as a 9.4% rainfall deficit in 2018 have accelerated the decline. In 2007-17, the water level in just 30% wells rose more than 2 metres, while it dropped by the same amount in 43% of the wells.
More alarmingly, just 6% showed a rise of 2-4 m in water levels while levels in twice that number feel by 2-4 m. The bad news piles on – water levels fell more than 4 metres in 7% of the wells, and rose by that amount in just 3%. This means the aquifers at all levels are being depleted. The trend remains the same in other decadal data sets of CGWB.
This means that overall, the water table has fallen in most of the observation wells. There was a fall in the water table of 2-4 m in 61% wells between 2007 and 2017 as against a rise of water levels in just 39% wells of the same amount. That means tube wells sunk in 2007 would need to be deepened by that amount or new wells sunk that are at least that much deeper than the old ones. In rural areas, the cost of this undertaking could vary from Rs 50,000-2 lakh, depending on the geology.
Another set of data, on the depth of wells, points in the same direction. In six years from 2011 to 2017, the percentage of shallow wells up to 2 m deep fell from 6% to 4%, or a third. The percentage of wells deeper than 5 m increased from 66% to 74%, an increase of about 10%. This again has implications for groundwater-dependent farmers, rural water supply systems and industry.
The sharpest fall in groundwater has been recorded in Punjab, Rajasthan, Haryana and Delhi. In these states, more groundwater is pumped than is recharged naturally. The National Aeronautics and Space Administration used the Gravity Recovery and Climate Experiment (GRACE) satellites to study groundwater extraction between 2003-2014. A decline in groundwater levels of up to 6 cm/year was recorded in these states as well as in Uttarakhand, Uttar Pradesh and Himachal Pradesh.
Groundwater is naturally recharged by rivers and rain. Natural rates of recharge are low, averaging 5% of the rainfall. These states (except Uttarakhand and Himachal Pradesh) get 500-1000 mm of rain annually – 25-50 mm of this soaks into the aquifers. Rivers recharge the groundwater as they have adequate water through the year. However, most rivers nearly run dry soon after monsoons end. A lot of the water in them comes from base flows from aquifers that have been recharged during the monsoons.
Agriculture, which uses about 80% of all water resources, is the largest user of groundwater as well. Some estimates put this at 70% of all water used by agriculture – the rest comes from surface sources and rainwater. Nearly 80% of water for drinking and other domestic uses comes also from groundwater. But perhaps the newest challenger is the biggest threat.
In the past decade, the urban sprawl in the national capital region (NCR) and around other metros has expanded at a rapid rate. One estimate puts the NCR population at 24 million, growing at 3.2% annually from 2000-2016. Mumbai with 21 million and Kolkata with 15 million have grown at 1.9% and 1.7%, respectively. Both Bangalore and Hyderabad have grown rapidly, at 2.5% and 2.3%, respectively.
What this means for water consumption
Government norms for megacities mandate a per capita water supply of 135 litres per day. For the NCR, this means 3,240 million litres per day (MLD), for Mumbai 2835, Kolkata 2025, Bangalore 1417 and Hyderabad, 1242 MLD. The actual supply is much higher – the Delhi Jal Board supplies more than 5000 MLD in the city. Several studies have shown that half of this is groundwater.
The groundwater equation is further unbalanced by the reduced area available for recharge. Concretisation in these urban sprawls has considerably reduced the natural recharge potential. Even though rainwater harvesting is included in building bylaws, builders obey them in letter, not spirit. Thus, the concretised natural catchments, that could otherwise become sources for rainwater harvesting, have instead become a barrier to groundwater recharge.
For most farmers, groundwater is the first source of irrigation water. Surface irrigation systems are notoriously unreliable. There are competing uses of water, notably industry and energy and water from irrigation systems is being increasingly diverted for non-agricultural use. The Bisalpur Dam in Rajasthan, made to help farmers irrigate their crops, now supplied water to Jaipur. Water from the Hirakud Dam is being diverted for industry use – this was built for irrigation purposes. Therefore, the agriculture sector resorts to groundwater to ensure the survival of crops.
Various estimates put the number of tube wells at more than 30 million across India. A majority of them are for agricultural use, installed by individuals or the government. The combined groundwater draught is calculated at nearly 60% of the total groundwater available for use. This is dangerously close to the threshold for overuse, which according to CGWB is 70%, given the observed long-term drop in aquifers.
In this scenario, the long-pending model groundwater bill must be put up for review by the public and experts and enacted at the earliest.
Nitya Jacob is based in New Delhi, with about 30 years’ experience as a journalist and policy advocacy expert.