The increase of human impact on the flora and fauna in the western Nile Basin from 10,000 years ago

The Nile River has the third-largest drainage basin in the world (3.2 million km2). Its western side has a very small extension in the stretch that runs through Egypt but becomes much more expansive in its upper extent, south of 20° N. The White Nile is the river’s main tributary in the western Nile Basin. At the onset of the Holocene, abundant White Nile floods resumed between 12,500 BC and 10,500 BC and formed a lake, the White Nile Lake, which filled much of the lower White Nile Valley. Early and mid-Holocene high flood levels occurred at 7700–7000 BC, 5900–5600 BC, and 5300 BC. Beside the White Nile, the upper river catchment collected water from other tributaries in western Sudan, including the Wadi Howar, the Wadi el-Melik, and the Wadi Muqaddam. The Wadi Howar, also called the Yellow Nile, originated in the Ennedi region of Chad. This and the other wadis became significant water courses by 7300 BC and linked western Sudan and Chad to the Nile Valley. They could sustain life when the surrounding areas became desert and human populations concentrated by the wadi courses after 4000 BC. They started drying up around 2800 BC and became extinct about 2000 years ago, even though water and pasture are still seasonally available today. Groundwater was another valuable water source, and several perennial lakes were developed throughout western Sudan. These lakes formed between plant-stabilized dunes and were connected to the Chad Basin through swamps and marshes between the lakes, allowing animal and human migrations.