For India, a looming freshwater crisis—the World Bank already puts the country’s per capita renewable freshwater resources at less than a fifth of the world, far behind the other four in the list of top-five populous countries—is set to become a nightmare. A study published in Nature Geoscience has found that, upto a depth of 200 metres, 60% of the groundwater in the Indian part of the Indo-Gangetic Basin (IGB)—comprising the riparine systems of the Indus, the Ganga and the Bramhaputra—has become unsuitable for drinking and irrigation, thanks to high arsenic content and excessive salinity. For perspective, groundwater withdrawal from the trans-boundary basin accounts for a quarter of the global withdrawal, and thus, high toxicity and salinity are likely to have rather severe and widespread ramifications. As per the study, while high levels of salinity is common in the Indus basin and the drier reaches of the Upper Ganga basin, high arsenic content seems to exclusively plague the IGB in southern parts of Bengal.
Part of the problem is because of natural causes such as excessive surface water evaporation but man-made factors like indiscriminate fertiliser and pesticide usage and thoughtless irrigation practices have also contributed their bit over the years. Between 2000 and 2012, the water-table has fallen in 30% of the highly-populated area that makes up the IGB in the north of the country, mostly in the states of Uttar Pradesh, Haryana and Punjab. With subsidised power fuelling reckless irrigation and heavily subsidised urea knocking soil chemistry off kilter, there can be no real change until these are dealt with first.