It was reported this week that more than 25% of the coconut trees in Chamarajanagar district have died and the others are following. This phenomenon is being attributed to severe depletion of the ground water. It has also been reported that when it rains, the ground is moist for a few days only and dries up very quickly. This lack of water is also severely affecting other crops.
Indiscriminate borewell drilling is the most probable cause of this extreme depletion of ground water. Geologists have known for some time that the depletion of the water table in areas of high borewell density is far in excess of what is expected after taking into account the rainfall variations and the increased ground water usage (which is now more than 20 times the use in 1960). So there has to be another reason. It has been now confirmed that ground water in the tight fracture-controlled aquifers in the state has found vents in the borewells for free flow from shallow zones to deeper zones. In other words, BOREWELLS ARE DRAINING WATER INTO DEEP UNDERGROUND. The land has become a sponge which sucks rainwater and sends it directly to deep underground. As a result, the surface runoffs have also diminished limiting the flow to tanks, tributaries and rivers. This is also the reason that even a perennial river like Kaveri is getting depleted earlier and earlier.
In such a situation, shallow ground water can not be recharged. Water directed underground by recharge pits will directly flow into deep underground and will not raise the water table. This has happened in many places in Karnataka where a large number of borewells have been sunk.
If the drilling of borewells continues at the current pace, we will soon reach the point when all the surface water will be drained into the deep underground and we will be left with no accessible water at all. DRYLAND AGRICULTURE WILL THEN DIE AND THE LAND WILL TURN INTO A DESERT.
To prevent such a catastrophe, we should seriously consider setting up a ground water authority consisting of experts and imposing a moratorium on private borewells except with the permission of this authority. Steps such as creation of subsurface check dams, plugging the vents (that allow water to flow from a shallow zone to a deeper zone) and recharging aquifers which are not drained to lower levels should be pursued with great urgency to undo the damage that has already been done.
V Mahesha, MGP
(The author, an expert on hydrogeology, worked in the Department of Mines and Geology for more than 35 years in all regions of Karnataka. He can be contacted at 98455 11109.)
V Mahesha, MGP
(The author, an expert on hydrogeology, worked in the Department of Mines and Geology for more than 35 years in all regions of Karnataka. He can be contacted at 98455 11109.)