Here's the watershed basins and sub-basins for India, which looked reasonable to me at a glance : https://www.indiawaterportal.org/articles/river-basin-and-sub-

Here's the watershed basins and sub-basins for India, which looked reasonable to me at a glance : https://www.indiawaterportal.org/articles/river-basin-and-sub-basin-map-india-central-ground-water-board https://www.indiawaterportal.org/articles/river-basin-and-su...