The river Jonk originates in the sonabeda plateau in Nuapada district of Orissa at an elevation of 700 m. The Jonk merges with the Mahanadi near Sourinarayan upstream of the Hirakud dam after traversing a distance of about 182 km. Machkanalla, Sukha nalla, Kantra nalla, Kermel nadi and Ranidhara nalla are the important tributaries. The sub-basin lies between north latitudes of 20°28' and 21°44' and the east longitudes of 82°20' and 83°00'. It drains an area of about 3,484 km2, which is nearly 2.46% of the total area of the Mahanadi basin.