One of the primary rivers that water the state of Orissa is the Brahmani. The river originates in the state of Bihar. It flows through several districts of Orissa forming a large catchment area before it meets the Bay of Bengal.
The Brahmani has its source in the Chhotanagpur Plateau which is the predominant physiographic feature of the state of Bihar. The Sankh and the Koel are the two rivers that are formed in the origin of the Brahmani. The confluence of the two rivers leads the formation of the Brahmani at Rourkela in the district of Sundargarh in Orissa. The river then passes through the districts of Cuttack, Dhenkanal, Kendujhar, Jajpur and Sundargarh in the state of Orissa. Before opening into the Bay of Bengal, River Brahmani blends with the Mahandi to form the delta known as the Dhamra.
The Brahmani runs along 799 kilometers from its origin to the mouth. In Orissa, the river stretches across 541 kilometers and forms a catchment area of 39,033 square kilometers. As a major source of water and hydroelectricity in the state, the river forms an important part of the study of the geography of Orissa.

