Sudd in the context of "Nile Basin"

South Sudan (/suːˈdɑːn, -ˈdæn/), officially the Republic of South Sudan, is a landlocked country in East Africa. It is bordered by Sudan to the north, Ethiopia to the east, the Democratic Republic of the Congo to the southwest, Uganda to the south, Kenya to the southeast and to the west by the Central African Republic. South Sudan's diverse landscape includes vast plains and plateaus, dry and tropical savannahs, inland floodplains, and forested mountains. The Nile River system is the defining physical feature of the country, running south to north across its center, which is dominated by a large swamp known as the Sudd. South Sudan has an estimated population of just over 12.7 million in 2024. Juba is the capital and largest city.

Sudan was occupied by Egypt under the Muhammad Ali dynasty and governed as an Anglo-Egyptian condominium until Sudanese independence in 1956. Following the First Sudanese Civil War, the Southern Sudan Autonomous Region was formed in 1972 and lasted until 1983. A second Sudanese civil war soon broke out in 1983 and ended in 2005 with the Comprehensive Peace Agreement. Later that year, southern autonomy was restored when an Autonomous Government of Southern Sudan was formed. South Sudan became an independent state on 9 July 2011, following 98.8% support for independence in a January 2011 referendum. It is the most recent sovereign state with widespread recognition as of 2025. South Sudan descended into a civil war from 2013 to 2020, enduring rampant human rights abuses, including forced displacement, ethnic massacres, and killings of journalists by various parties. It has since been governed by a coalition formed by leaders of the former warring factions, Salva Kiir Mayardit (Sudan People's Liberation Movement or SPLM) and Riek Machar (Sudan People's Liberation Movement-in-Opposition or SPLM-IO). The country continues to recover from the war while experiencing ongoing and systemic ethnic violence.

Flooded grasslands and savannas is a terrestrial biome of the World Wide Fund for Nature (WWF) biogeographical system, consisting of large expanses or complexes of flooded grasslands. These areas support numerous plants and animals adapted to the unique hydrologic regimes and soil conditions. Large congregations of migratory and resident waterbirds may be found in these regions. The relative importance of these habitat types for these birds as well as more migratory animals typically varies, as the availability of water and productivity annually and seasonally shifts among complexes of smaller and larger wetlands throughout a region.

This habitat type is found in Asia, Africa, North America and South America. Some globally outstanding flooded savannas and grasslands occur in the Everglades, Pantanal, Lake Chad flooded savanna, Zambezian flooded grasslands, and the Sudd. The Everglades, with an area of 7,800 sq mi (20,000 km), are the world's largest rain-fed flooded grassland on a limestone substrate, and feature some 11,000 species of seed-bearing plants, 25 varieties of orchids, 300 bird species, and 150 fish species. The Pantanal, with an area of 187,818 km (72,517 sq mi), is the largest flooded grassland on Earth, supporting over 260 species of fish, 700 birds, 90 mammals, 160 reptiles, 45 amphibians, 1,000 butterflies, and 1,600 species of plants. The flooded savannas and grasslands are generally the largest complexes in each region.

Lake No is the largest lake in South Sudan, which is locally known as Dhoo Lake by Ruweng Panaruu community. It is located just north of the vast swamp of the Sudd, at the confluence of the Bahr al Jabal and Bahr el Ghazal rivers, and marks the transition between the Bahr al Jabal and White Nile proper. Lake No is located approximately 1,156 km downstream of Uganda's Lake Albert, the major lake on the White Nile preceding Lake No. The lake is considered the center of the Ruweng people of Panaruu section of Dinka peoples.

The Bahr el Ghazal (Arabic: بحر الغزال, lit. 'sea of gazelles') or Naam River (Nuer) is a river in South Sudan. The South Sudanese region of Bahr el Ghazal takes its name from the river.

The Bahr el Ghazal is the main western tributary of the Nile. It is 716 km (445 mi) long, flowing through the Sudd wetlands to Lake No, where it joins the White Nile.