Drying out

17th of Aug 09

We have long known that India is running itself to the ground, as far as the water table is concerned. With our neglect of irrigation, our heavily extractive farming practices and indeed urban drilling, the rate of groundwater depletion has raced far past the rate of replenishment in many states, but hydrological data has been sparse. Now, never-seen-before NASA satellite images have provided a big picture of the big trouble we’re in. According to a study published in Nature, 109 cubic kilometres of groundwater have been lost in Rajasthan, Punjab and Haryana between August 2002 and October 2008, a period of normal rainfall — that’s twice the capacity of India’s largest water reservoir.
Groundwater is an invisible but invaluable resource, formed by the steady drip of precipitation and surface wetness down through layers of clay and stone, accumulating in natural aquifers underground. Some such cavities may contain water thousands to millions of years old, while in others, water levels recede and rise every year. In India, groundwater irrigation has been expanded after the late ’60s, when high-yield crop varieties were introduced. This led to great leaps in productivity, provided food security and acted as a drought buffer — yields from groundwater irrigated areas are likely to be greater by one-third to a half compared to surface irrigated plots. It is estimated that as much as 70 to 80 per cent of India’s agricultural output may rely on groundwater. Special agricultural strategies for north and eastern India in the ’80s were deeply groundwater-dependent, drilling free tube-wells and subsidising pump sets. Growing water-guzzling crops like paddy and the consequent groundwater mining to keep up have resulted in having to dig deeper and deeper.