Ground Water Overexploitation through Borehole Technology

Borehole Technology D S K Rao In Karnataka state, as in many other parts of the country, well irrigation came into prominence since the 1960s, Since then rapid increase of wells and pump sets tookplace. This resulted in sharp decline of water levels, which is more evident in the low rainfall, hard rock areas of the state, particularly in the four south-eastern districts of Bangalore, Chitradurga, Kolar and Tumkur.

Detailed study of two small watersheds in Malur taluka of Kolar district and Davanagere taluka of Chitradurga district was conducted in February 1993 to understand the serious implications of water level decline in hard rock areas of Karnataka. Farmers tackled the problem of declining water levels by constructing bore wells, which actually triggered even more rapid decline of water levels because these structures, by virtue of their depth, are capable of yielding more water than the conventional dug wells. As a consequence, dug wells became dry and investment on them along with thepumpsets became infructuous. Thus, large number of farmers who had assured dug well irrigation a few years back are now deprived of irrigation because they did not have resources to attempt boring after the dug well became dry, or because the bore well they attempted did not prove successful Such farmers have now switched over to dryland farming and the poorer among them are supplementing their meagre and uncertain farm income through agriculture labour.