[3] Like many other seasonal Indian rivers, the Mahanadi too is a combination of many mountain streams and thus its precise source is impossible to pinpoint.

Presently, only 169 square kilometres (65 sq mi) basin area of Hasdeo River in Anuppur District lies in Madhya Pradesh.

Before the construction of the dam in 1953, the Mahanadi was about a mile wide at Sambalpur and carried massive amounts of silt, especially during the monsoon.

Today, it is a rather tame river after the construction of the dam and is joined by the Ib, Ong, Tel and other minor streams.

It then skirts the boundaries of the Baudh district and forces a tortuous way between ridges and ledges in a series of rapids until it reaches Dholpur, Odisha.

The rapids end here and the river rolls towards the Eastern Ghats, forcing its way through them via the 64 kilometres (40 mi) long Satkosia Gorge.

The river enters the Odisha plains at Naraj, about 14 kilometres (8.7 mi) from Cuttack, where it pours down between two hills that are a mile apart.

The Kathjori then throws off many streams like the Kuakhai, Devi and Surua which fall into the Bay of Bengal after entering the Puri district.

The cities of Cuttack and Sambalpur were prominent trading places in the ancient world and the river itself has been referred to as the Manada in Ptolemy's works.

However owing to its seasonal nature the river is mostly a narrow channel flanked by wide sand banks for most of the year.

However heavy rain can still cause large-scale flooding as evidenced in September 2008 when 16 people died as the river breached its banks.

In September 2011, heavy downpour caused flash flood and many mud dwellings in more than 25 villages above Hirakud Dam in Chhattisgarh and Odisha, which were never affected before, collapsed due to back water that could not pass through the river.