Option 1: Hemavati is a tributary of the river Cauvery. This means that Hemavati flows into the river Cauvery and contributes to its water flow. Therefore, option 1 is not the correct answer.

Option 2: Arkavati is also a tributary of the river Cauvery. Similar to Hemavati, Arkavati flows into the Cauvery and adds to its water volume. Hence, option 2 is not the correct answer.

Option 3: Indravati is not a tributary of the river Cauvery. It is an important river in the central parts of India, specifically in the state of Chhattisgarh. Therefore, option 3 is the correct answer.

Option 4: Amravati is not a tributary of the river Cauvery. It is a river in Maharashtra, which flows through the districts of Amravati and Nagpur. Thus, option 4 is not the correct answer.

Therefore, the correct answer is option 3, as Indravati is not a tributary of the river Cauvery.