Which river flows through the Sudd, one of the world's largest wetlands?

The White Nile flows through the Sudd, one of the world’s largest wetlands.

The Sudd is a vast swamp and floodplain in South Sudan formed chiefly by the White Nile’s Bahr al-Jabal, or “Mountain Sea,” section. After entering the wetland near Mongalla, the river spreads into a maze of shallow channels, lagoons, reed beds and papyrus-covered areas. Near Malakal, the system continues northward as the White Nile.

The wetland’s flat terrain and dense vegetation greatly slow the river, causing enormous water losses through evaporation and plant transpiration. Its area changes dramatically with seasonal rainfall and upstream flows: the permanent and seasonal flooded region can expand from tens of thousands of square kilometres to well over 100,000 during exceptionally wet conditions.

The Sudd is also the source of several common naming confusions. The Sobat River joins the White Nile near Malakal, but it does not form the main river flowing through the wetland. The Bahr el Ghazal and Bahr el Zeraf are connected channels or tributary systems within the broader swamp. The Blue Nile meets the White Nile much farther north at Khartoum.