Cauvery Basin: Groundwater and Acquifers

Cauvery basin includes around 11,000 sq km of sedimentaries in the delta region and the remaining area is occupied by hard rocks. In granite region, weathered zones form the shallow aquifers, the average depth of weathering is around 15 m. Deeper semi confined to confined aquifers occur at depths more than 200m as well, as the fractures are very deep seated. In some areas underlain by crystalline rocks, ground water is limited to fractures, joints and weathering. While weathered gneisses can yield upto 400 m3/day, unweathered rocks and charnockites yield only around one tenth of that. Potential aquifers occur in various part of extensively weathered and fractured hardrocks. As extensive development has already taken place in some areas, further development should be done with caution. Several areas in the basin seem to have Fluoride content more than 1.5 ppm in the ground water.
 
Potential aquifers occur in the sedimentaries and so western part of Cauvery delta may have a potential for future groundwater development. The eastern margins of the delta are slightly mineralized and so caution is required to exploit this further along with considering issues like salt water intrusion.