When the rivers go dry – and how groundwater over-abstraction killed itNovember 21, 2012
On The death of rivers and the role of groundwater extraction in the killing
Water can be both good and bad, useful and dangerous. To the danger, however, a remedy has been found, learning to swim- Democritus.
The time of Democritus (460 – 370 BCE) was a happier one for waters, be they rivers or lakes or the sea. It was not the era of pollution from sewage and industries or the era of unbridled exploitation through overuse and over-extraction , especially of groundwater, posing a much greater challenge than to learn to swim to deal with dangerous waters.
Now rivers and lakes are drying up. A primary cause is the lowering of the water table in the catchment zones. As ground waters go deeper they no longer emerge as seeps and springs to feed rivers. Whatever little water is there in these water bodies now either evaporate or re- enter the ground to be further exploited.
A recent publication by the US Geological Services – USGS – titled ‘ Stream-flow Depletion by Wells—Understanding and Managing the Effects of Groundwater Pumping on Stream-flow’ examines the phenomenon.
Its conclusion is that by far the biggest influence on depleted river flows is groundwater pumping. It also clears up several misconceptions. The belief for example that the total development of a groundwater aquifer system is ‘safe’ or ‘sustainable’ up-to the average rate of recharge. A system currently followed by our planners. This, the paper argues, is wrong. The second myth that depletion stops when pumping of groundwater ceases. This too is a false belief.
In our immediate neighbourhood many attempts have been made to revive rivers and some are still ongoing. Say for example the effort of the Cauvery Niravari Nigam to revive the river Arkavathy. While crores of rupees are being spent on chopping bushes and cleaning drains not one paisa is spent towards understanding the groundwater and surface water flow interface and to manage the groundwater in such a way that it does not render the Arkavathy a losing stream. Good intentions are simply not enough for reviving water bodies. They have to be backed by a scientific rigour and analysis and the understanding that groundwater plays the biggest role in river and lake inflows.
The survival of a river or a lake cannot be the peripheral activity of many institutions it has to be the core activity of one institution. It is time we constituted a river basin institution for each one of the tributaries of the Cauvery and the Krishna and started planning and implementing appropriate groundwater management strategies to ensure that the river systems remain healthy. That would be water wisdom.