Tamils has more right over Cauvery because of the following historical facts.
1. Karnataka people doesn't know about agriculture, irrigation etc. We Tamils went there and teached all these technics to them.
2. 2000 year before iteself we built the Kallanni Dam in Cauvery near Trichy for paddy cultivation, at that time there were no paddy cultivation happened in Cauvery, Kannadigas came here to TN and learnt all these paddy cultivation technics from TN farmers.
3. If TN stops Neyveli Lignite power to Karnataka, then the Bangalore and half of the Karnataka will become dark in overnight.
We the people gave the knowledge of agriculture and light to the IT of Karnataka.
So Karnataka is not doing any favour by releasing Cauvery water, its their duty to do so and its Tamil's Right.