Nature magazine has a great video of North India heading towards a water calamity. Groundwater is dropping more than 1 foot per year on average and over the last 6 years about 109 cubic km of water has been pulled out of aquifers underlying northwestern plains of India.Recent measurements of water loss were done by twin satellites called GRACE – NASA's Gravity Recovery and Climate Experiment. These satellite orbit the earth at a set distance from each other and instead of taking measurements of objects directly below, they look at each other and measure changes in orbit due to variations in the pull of gravity.
The result is summarized below. Red areas depict areas of groundwater loss and blue areas of groundwater gain.
Although striking, the measurements of the Punjab area should not come as a big surprise. Depletion of the groundwater table has been known to be taking place for many years but presenting the results in such a pictorial form and as volumes does make one sit up.
My attention however was drawn to the blue areas in the central parts of the country. They show a groundwater gain. This has been interpreted as due to above average rainfall for the last several years. No doubt that has played a role, but that hides a more general pattern.
I've written about this region before and the link between groundwater accessibility, use and farmer poverty.
Population densities of this dry interior region are less than the northern plains. Even so, groundwater is an underexploited resource per capita as compared with the northern plains of the country. Geology does play a big part in it. The terrain is all hard rock aquifers which are heterogeneous and compartmentalized and finding groundwater is not easy. Its also very expensive to dig a dug well or drill a bore well so many poor farmers end up relying on rains for their water needs. Vast tracts of this region are not supplied by surface irrigation canals and groundwater must be made more accessible if the widespread problem of reliable water supply to farmers is to be solved.
I want to put up this figure again to emphasize how important groundwater is to the Indian agricultural economy.
More than a decade on the importance of groundwater in agriculture holds and is growing. But till now groundwater has been seen as a resource to be extracted without giving any thought to the long term viability of such an approach. We need to change that mindset and steer it towards one that recognizes that just finding groundwater is not going to be enough. The sensible scientific management of the resource is just as crucial.
Maybe we still don't get it. Sadanand who blogs at Chintan has a post that highlights how we think about water and the solutions to scarcity. Irrigation canals and dams serve only 15% of arable land in India but that's what the apparent solution is in the minds of government and media alike. Groundwater which serves the rest and which will become even more important in the context of climate change is still being neglected.