The river Cauvery spans about 800 kilometer long, and basin of this river is roughly 81,155 square kilometer in area. While over 50 per cent of the river flows in the lower stream-Tamil Nadu, 34,273 sq km, only 2,866 sq km flows in Karnataka, and 160 sq km each in Kerala and in Puducherry.
The tug of war for water between the two states related to it’s release from Karnataka continued for the past 125 years and worsened whenever the state received minimum rainfall which ultimately brought down the level Cauvery in years 1995 and 2002.
To resolve this growing conflict, the Government of India set up a Tribunal, by the instructions of Supreme court. This tribunal after analyzing the issue issue a final verdict in Feb 2007 that Tamilnadu should get 419 billion cubic feet of water, Karnataka, 270 billion cubic feet, Kerala, 30 billion cubic feet and Puducherry was to get seven billion cubic feet of water.
The states were convinced with the verdict and they filed petition to review the decision of the tribunal. Thus in 2012 the Cauvery river authority instructed the state to release 9,000 cusesc of water to Tamilnadu, which the state didn’t follow. Ultimately Tamilnadu filed a case at Supreme Court and received a favorable order, which was again violated by Karnataka in June 2013.
This issue came into limelight again during August when Tamilnadu again filed a petition at Supreme Court. Karnataka again raised concerns for releasing the water due to the reduced rainfall and no water in the states’ reservoirs.
This complaint of Tamilnadu has now got the verdict from the supreme court that Karnataka should release 15,000 cusesc of water which is the sole reason for the riots happening.