[1][a] The river originates in the south of the states of Western Equatoria not far from the border with Haut-Uélé in the Democratic Republic of the Congo.

[3] It flows north from Western Equatoria through Tonj South County in Warrap into Unity State.

About the end of March this section is liable to be swollen by the early rains and cannot be forded by a motor vehicle.

[1] To the north of Tonj, the river enters a large lagoon from which several small watercourses lead into a grass swamp.

[8] Each year Warrap experiences flood from July to December, with some parts being totally isolated.