Nile River

Nile River, the longest river in the world, called the father of African rivers. It rises south of the Equator and flows northward through northeastern Africa to drain into the Mediterranean Sea. It has a length of about 4,132 miles (6,650 kilometres) and drains an area estimated at 1,293,000 square miles (3,349,000 square kilometres). Its basin includes parts of Tanzania, Burundi, Rwanda, the Democratic Republic of the Congo, Kenya, Uganda, South Sudan, Ethiopia, Sudan, and the cultivated part of Egypt. Its most distant source is the Kagera River in Burundi.

The Nile is formed by three principal streams: the Blue Nile and the Atbara which flow from the highlands of Ethiopia, and the White Nile, the headstreams of which flow into Lakes Victoria and Albert.

The name Nile is derived from the Greek Neilos, meaning a valley or a river valley and hence, by an extension of the meaning, a river. The fact that the Nile—unlike other great rivers known to them—flowed from the south northward and was in flood at the warmest time of the year was an unsolved mystery to the ancient Egyptians and Greeks. The ancient Egyptians called the river Ar or Aur (Coptic: Iaro), “Black,” in allusion to the colour of the sediments carried by the river when it is in flood. Nile mud is black enough to have given the land itself its oldest name, Kem or Kemi, which also means “black” and signifies darkness. In the Odyssey, the epic poem written by the Greek poet Homer (7th century BCE), Aigyptos is the name of the Nile (masculine) as well as the country of Egypt (feminine) through which it flows.

The Nile River basin, which covers about one-tenth of the area of the continent, served as the stage for the evolution and decay of advanced civilizations in the ancient world. On the banks of the river dwelled people who were among the first to cultivate the arts of agriculture and to use the plow. The basin is bordered on the north by the Mediterranean; on the east by the Red Sea Hills and the Ethiopian Plateau; on the south by the East African Highlands, which include Lake Victoria, a Nile source; and on the west by the less well-defined watershed between the Nile, Chad, and Congo basins, extending northwest to include the Marrah Mountains of Sudan, the Al-Jilf al-Kabīr Plateau of Egypt, and the Libyan Desert (part of the Sahara).

The availability of water from the Nile throughout the year, combined with the area’s high temperatures, makes possible intensive cultivation along its banks. Even in some of the regions in which the average rainfall is sufficient for cultivation, marked annual variations in precipitation often make cultivation without irrigation risky.

The Nile River is also a vital waterway for transport, especially at times when motor transport is not feasible—e.g., during the flood season. Improvements in air, rail, and highway facilities beginning in the 20th century, however, greatly reduced dependency on the waterway. It is thought that approximately 30 million years ago the early Nile, then a much shorter stream, had its sources at about 18° to 20° N latitude. Its main headstream may then have been the present Atbara River. To the south lay the vast enclosed drainage system containing the large Lake Sudd. According to one theory on the evolution of the Nile system, about 25,000 years ago the East African drainage to Lake Victoria developed an outlet to the north, which sent its water into Lake Sudd. With the accumulation of sediments over a long period, the water level of this lake rose gradually, and, as a result of the overflow, the lake was drained, spilling over to the north. The overflow waters of Lake Sudd, rapidly forming a riverbed, linked the two major parts of the Nile system, thus unifying the drainage from Lake Victoria to the Mediterranean Sea.

The basin of the present-day Nile falls naturally into seven major regions: the Lake Plateau of East Africa, the Al-Jabal (El-Jebel), the White Nile, the Blue Nile, the Atbara, the Nile north of Khartoum in Sudan and Egypt, and the Nile delta.

Britannica