It originates at the Lawapani Waterfalls, near Lohardaga, Chota Nagpur Plateau 82.5 kilometres (51 mi) from Ranchi, and conjoins the Belsiangar and Singbhum Rivers.

[1] The South Koel enters Odisha and joins with Sankh River at Vedavyas near Rourkela from where it is named as Brahmani.

The watersheds of these three systems originate near Gamharia in the Kolhan and radiate north-west, south-west and east respectively from their common, centre.

The 1.521 kilometres (1 mi) long Saranda railway tunnel on the South Eastern Railway Howrah - Mumbai Main Line divides the Subarnarekha and Brahmani systems, and at this point the watershed leaves the Kolhan, continuing in a northerly direction through Porahat and finally merging in the Ranchi plateau between the Bicha and Tatkora hills.

The Baitarani forms for about 12 kilometres (7 mi) the boundary between the Kolhan area and Keonjhar (in Odisha) while the Brahmani drains the west of the district through its tributary, the South Koel, and its feeders, the North Karo and the South Karo, and the latter of which in its turn is fed by the Deo river.