In a setback to Tamil Nadu, Supreme Court on Friday reduced its share of Cauvery river water to 177.25 thousand million cubic feet (tmcft) down from 192 tmcft allocated by a Tribunal in 2007.A bench of Chief Justice Dipak Misra, Justice Amitava Roy and Justice A.M. Khanwilkar reduced the share of the state as it noted that the Cauvery Tribunal had not taken into account the ground water available in Tamil Nadu's side of the river basin.Consequently, the share of Karnataka has been increased by 14.75 tmcft, which includes increased allocation for "global" city of Bengaluru for drinking purposes.Allocating 4.75 tmcft to Bengaluru, Chief Justice Misra pronouncing the judgement said that Karnataka can use the increased allocation for irrigation and industrial purposes by marginally increasing its area under crop.While bringing down the allocation for Tamil Nadu, the top court kept intact the allocation made to Kerala and Puducherry by the Tribunal.The court directed that as per the Tribunal award, the Centre would take steps for setting up the Cauvery Water Management Board for the implementation of the interim water sharing arrangement, which it (court) said would remain in operation for the next 15 years.