Groundwater reaching dangerous levels

It is estimated that 85% of rural and 50% of urban population is dependent on groundwater

The summer is upon us. Given the Met forecast, it is going to be harsher than ever. By March-end, the surface water across the nation turns turbid and is rendered unutilisable. Next four months (till the fresh precipitation starts), it is groundwater (GW) that sustains lives, farming, industries, and commercial and construction activity.

India receives 4,000 billion cubic metre (bcm) of water through rainfall annually. Of this only 1,137 bcm is utilisable and the rest add to the river flows. Of the 1,137 bcm, 690 bcm fills the surface water bodies while another 447 bcm seeps into the ground. Thus, net availability of groundwater is measured at 447 bcm. Of this, 411 bcm is accessible for extraction.

By annually drawing 251 bcm of groundwater, India tops the list of top 10 groundwater-extracting countries and is the largest user of the precious liquid from the bowels of the earth. By extracting 251 bcm, the nation exhausts a little over 62% of the GW resource annually. As for Karnataka, net availability of GW is 15 bcm. Of this, the state extracts 61%.

Groundwater is the most preferred source of water, given its ubiquity and accessibility. Stored within the ground, it is shielded against the harsh sun and thus least prone to evaporation. Anonymity and thereby intractability of the extractor leads to difficulty in management and lack of control over its extraction.

It is estimated that 85% of rural and 50% of urban population is dependent on GW. About 65% of total irrigated land gets its supplies from the groundwater resources and 85% of this came to be added after 1970. The irrigated area progressed from 6.5 million hectares in 1951 to 65 million hectare in 2015, a 10-fold quantum leap.

This was owing to the introduction of several water-intensive crops that heralded the Green Revolution and have ensured food security on a sustained basis thereafter. About 90% of the extracted GW is used for irrigation. The global average of groundwater being used for irrigation is somewhere around 40%.

Crisis Zones: Most of northern Punjab, southern Rajasthan, eastern Haryana, western Uttar Pradesh, northern Karnataka, almost entire Rayalaseema, large parts of Tamil Nadu, parts of Madhya Pradesh and southern parts of West Bengal lie among region where GW is over-exploited.

According to D Subburaj, till recently regional director, Central Ground Water Board, of Karnataka’s 176 taluks, 45 taluks fall under the category of over-exploited groundwater. Another eight are critical, 26 under a semi-critical category. The situation can be called safe only in 97 taluks. Bengaluru Urban and Rural districts and all surrounding districts fall under the over-exploited zone.

Water-stressed: The pressure on varied sources of freshwater is not difficult to fathom given the country’s vast populace and limited resources. Once a water-rich civilisation, India is today categorised under water-stressed nations.

Against the global average of per capita 7,600 cubic metre annual availability of freshwater, the figure for India is merely 1,545 cubic metre annually (Brazil 41,865; US 9,802; China 2,060 cubic metre annually). In the last 50 years, the per capita water available in India has shrunk by 70%.

The gravity of pressure on the groundwater could be understood in the light of facts presented by the Unesco’s World Water Development Report. It says in the case of 54% of wells, the water level has declined over the past seven years.

Furthermore, the ominous forebodings should not go unheeded. The 2018 report predicts that 21 major cities of the nation are likely to run out of groundwater by 2020. In the light of the severity of the situation, the NITI Aayog had emphasised dual initiative approach: firstly, the need to cut down dependence on groundwater and secondly, to take up measures for source augmentation.

Cut Subsidy: As for the first, need is being felt to reduce subsidy on power consumed by irrigation pumps, which in most cases function inefficiently. In most states, power supplied to farms is either free or is billed at a flat rate without taking into cognizance the units consumed or water extracted.

This leads to both overexploitation of groundwater and overconsumption of power. An analysis of panel data across 370 districts within the country revealed that a reduction in power subsidy was correlated with a decrease in groundwater extraction.

On average, a 10% reduction in power subsidy led to a 6.5% decrease in groundwater extraction. However, this being politically unpopular, maybe a risky proposition for the ruling dispensations. Alternatively, it is suggested that farmers be provided cash incentive for every unit saved after the introduction of billing.

Source Augmentation: As for augmentation of groundwater source, nothing has been found more useful than rainwater harvesting. Subburaj says even if 80% of the rainwater falling on a 100 sq metre area could be harvested, it would lead to a collection of 48,000 litres of water, given the annual average of 60 cm rainfall.

Unless the country wakes up to the dual challenge of replenishing the sources and regulating the growing demand for groundwater, the crisis is set to assume graver proportions.