The Indus and Ganges-Brahmaputra Basins are drying up faster than we’d like

The Wire
June 22, 2015

To the north, India is flanked by two giant groundwater aquifers – the Indus Basin to the west and the Ganges-Brahmaputra Basin to the east. Between them, they underlie a surface area of over 2.2 million sq. km and water from them supports the livelihoods of about 800 million people. That’s an area the size of the Democratic Republic of the Congo and the population of the United States, Indonesia, Brazil and Malaysia combined. What would happen if it was announced today that these countries’ water supplies were terribly distressed and under threat of running dry? The effect on the world’s economy would be disastrous, not to speak of what this would do to social peace in the affected countries.

If a recent NASA survey is to be believed,  the two basins which hold up two among the world’s largest agricultural regions including India’s breadbasket are, in fact, running dry. The Indus Basin is the second-most overstressed on the planet, its water levels falling by 4-6 mm/year. The level in the Ganges-Brahmaputra Basin, which is relatively less stressed, is still falling by 15-20 mm every year. The findings were published last week in two papers in the journal Water Resources Research.

Annual groundwater level decline rates of the 37 largest aquifers. Credit: NASA/JPL
Annual groundwater level decline rates of the 37 largest aquifers. Credit: NASA/JPL (Click on the image to enlarge)

The data supporting these alarming conclusions was collected by the twin Gravity Recovery and Climate Experiment (GRACE) satellites between 2003 and 2013. According to the Jet Propulsion Laboratory, California, which helps operate the satellites, eight of the world’s 37 largest subterranean aquifers are receiving “little to no replenishment” while five more are extremely stressed, “depending on the level of replenishment in each”. The most stressed is the Arabian Aquifer System that’s straddled by the Arabian desert region, and the second-most stressed is the Indus Basin.

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Pumping, sedimentation and salinity

The origins of the Indus Basin’s stresses can be traced to 1948, when, after Partition, India cut off water supplies to Pakistan stemming from the three chief tributaries of the Indus river: Ravi, Beas and Sutlej. As a result, the construction of a continuous irrigation system climbed to the top of Pakistan’s priorities as a young and developing nation. When the Indus Water Treaty was signed in 1960 after extensive negotiations, Pakistan moved to replace its inundation canals with canals and barrages that diverted water from the three tributaries as well as the Indus to its farms.

Today, the country possesses the world’s largest contiguous irrigation system, according to a Food and Agriculture Organization report, using 63% of the water from the river and its tributaries. India uses 36% and the remaining is split between Afghanistan and China. These developments have depleted groundwater in the basin, especially rapidly during periods of deficient rainfall and droughts, and have in some years left behind so little water that none reached the sea.

Apart from reducing quantities of water available, the quality of the water is also under threat because of sedimentation and increasing salinity, which are by-products of falling groundwater levels. An influential study conducted by V.M. Tiwari and others had found back in 2009 that the amount of water in the basin fell by 10 trillion litres a year from April 2002 to June 2008. The Indian Ministry of Water Resources announced in 2011 that Punjab and Haryana had annual water overdrafts of 9.89 trillion and 1 trillion litres respectively. Moreover, the Indus river also carries over 290 million tonnes of sediments from the Himalayan and Karakoram ranges every year.

Regulating supply and demand

Because of these additional stresses, rehabilitative efforts have focused on regulating both water supply and demand. India’s efforts to regulate water supply have been widely regarded as successful, especially after the Green Revolution period of 1960-1990 when community-driven initiatives proliferated. An illustrative example is the work of Rajendra Singh, a Ramon Magsaysay award recipient and winner of the Stockholm Water Prize in 2015, whose NGO – Tarun Bharat Sangh – has led the construction of traditional catchment structures called johads to trap rainwater and use it to recharge groundwater in the semi-arid areas of Rajasthan.

However, a problem with planning plagues water supply. As Ramaswamy Sakthivadivel writes in a paper for the International Water Management Institute, the “practice of pumping-induced recharge water outside the command area has had a very negative effect in managing large irrigation systems due to the siphoning of a considerable quantity of water to areas not originally included in the command”. The effects of this practice are exacerbated by increasing population.

While Pakistan has repeatedly complained that India has been violating the Indus Water Treaty by building an overabundance of dams on the Jhelum river, experts have pointed out that by being upstream of the river, India can build how much ever it wants as long as it doesn’t use more than the 1.50 MAF it’s allowed to under the treaty. Of course any debates surrounding this issue are mired in political controversies, but making matters doubly worse for Pakistan is a fractal image of the controversy playing out within Pakistan itself. Two provinces that use a lot of water from the Jhelum are Punjab and Sindh. However, Punjab is upstream of Sindh and also more politically influential, muscling more of the water into its territory before Sindh can have its share.

Ecological threats in the Ganges Basin

While the Ganges-Brahmaputra Basin faces similar problems – not surprising considering it’s the most densely populated river basin – it faces some unique ecological threats as well.

The Ganges Basin subset has had the Indian government’s eye on it for the installation of at least six hydroelectric projects. Controversy erupted in February 2015 when the environment ministry informed the Supreme Court that the projects had acquired almost all the necessary certificates and that their construction should begin. As Business Standard reported, experts “had also warned these dams could have a huge impact on the people, ecology and safety of the region, and should not be permitted at all on the basis of old clearances”. Soon after, the ministry conceded that it would let the experts take the final call – before setting up a new committee in June to review the projects once more.

The two GRACE papers come at an opportune time. While American concerns about hydrological issues are centered around the ongoing drought in California, the papers confirm that similar problems are playing out in far-flung parts of the world and that we must do more to secure these once-renewable resources. Jay Famiglietti, senior water scientist at JPL, stated, “Available physical and chemical measurements are simply insufficient.” “We don’t actually know how much is stored in each of these aquifers,” Alexandra Richey, the lead author on both papers, said, adding that estimates “of remaining storage might vary from decades to millennia.” She recommended using invasive probes like drilling to make better estimates.

The GRACE satellites are the result of a collaboration between NASA and Deutsche Forschungsanstalt fur Luft und Raumfahrt (DLR) in Germany. They measure changes in groundwater levels by mapping the resultant minuscule changes in Earth’s gravity in the region of space directly over the basins. As a result, the measurements are more reliable for larger basins where the effects are relatively more tangible. The stress levels are measured as a ratio of use to availability, the latter in turn being dependent on recharge rates, proportionate to their relative sizes.