In which Indian river is the islands of Sivasamudram & Srirangam are Situated?

Kaveri formed two islands in Karnataka (Srirangappattinam and Sivasamudram) and Srirangam island in Tamilnadu.

The Kaveri thrice forks into two streams and reunites a few miles farther on, thus forming the islands of Srirangapattanam, Sivasamudram and Srirangam.