That exploding economic growth brings with it an array of issues affecting the environment is now a well-proven axiom. Perhaps the most vulnerable among all natural resources to the “untamed” development is water. The recent ‘Aquifer Atlas’ released by the Central Ground Water Board (CGWB) reiterates what many scientists and environmentalists have been stressing on: manage or perish.
A culmination of decades-long data collection, the atlas, released in New Delhi, provides a sneak peek into what the current state of our ground water systems are.
The document pertaining to Tamil Nadu could perhaps be termed a warning signal, with the maps showing that more than any other southern State, exploitation of this crucial resource has been most rampant here.
Let us crunch some numbers. While the State has been divided into 386 assessment units (blocks), 139 have been categorised as “over exploited”.
In layman terms, this means the amount of water pumped out of the ground in these blocks is much hi-gher than the quantum of water that percolates into the aquifers.
These over-exploited units apart, 33 blocks have been termed critical and 67 semi critical, with chances of tripping into higher exploitation territory very high.
Significantly, 11 such units have been termed saline, raising questions on sea water intrusion.
There is also a trend in the depletion data. The most-affected regions seem to be in West Tamil Nadu consisting of districts such as Coimbatore, Dharmapuri and Krishnagiri where the ground below is typically made of hard rocks.
In these regions, maps showed that the groundwater was typically found below 20 metres in many pockets, the deepest range in the classification.
Officials noted that in Chennai, given the rapid growth in population accompanied by drawing of more water, there are clear-cut signs of the aquifers showing vulnerability to sea water intrusion.
Meanwhile, one encouraging factor in the State, data shows, is a decrease of six per cent in ground water draft (amount of water withdrawn) between 2004 and 2009.
The typical reasons laid out for such a trend in the introduction to the atlas, are reduction in irrigation drafts due to urbanisation and a dip in number of dug wells used for domestic purposes.
Officials said that the current atlas, which is on a considerably higher scale of mapping, is only a stepping stone.
Soon, mapping of ground water resources at the village level would be initiated so that the data could be put to use even at an individual level.
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