In the Kishkindha Kanda of the Ramayana, Sugriva sends Vanaras in all four directions to look for Sita. He describes the locations they’ll come across when they go in these directions in this chapter and subsequent chapters of the Kishkindha Kanda. Now scholars have noted that these are not directions relative to Kishkindha. Govindaraja, the Sri Vaishnava commentator on the Ramayana, gives more specificity on what place these directions are in relation to. Here is what page 299 of this book says:
[Different commentators] all try to establish a center in relation to which these geographical locations may be considered east. They choose a middle country, the Aryavarta, “abode of Aryans”, lying between the Himalayas and the Vindhyas. But they give no north-south Axis. [Govindaraja] even describes a river named Sharavali, which flows like a bracelet between those two mountain ranges, and names that as the center.
My question is, what is the Sharavali river mentioned by Govindaraja? Are there any circular rivers today that flow between the Himalayas and Vindhyas?