How the Nile River Works

The Nile boasts a long and complex route, winding its way through nine countries­ and a myriad of landscapes, including swamps, savannas, desert, rain forests and mountain highlands. The Nile owes its great length to the union of two main tributaries: the White Nile and the Blue Nile. The White Nile flows from the newly established source in Rwanda through the original source of Lake Victoria. When it reaches Khartoum in the country of Sudan, it joins forces with the Blue Nile, which originates in the Ethiopian mountains. The Nile's only other large tributary is the Atbara River, which joins the Nile in the eastern portion of Sudan. Although the White Nile -- the easier portion to navigate -- is considered the longer section of river, the Blue Nile provides roughly two-thirds of the total water supply to the river.

Both tributaries are named for the color of the water they contribute. At its source, the Blue Nile is bright blue, then darkens in Sudan where it begins to carry black sediment. The White Nile carries light gray sediment, turning the water more whitish-gray in color.

After the Blue Nile and the White Nile join forces in Khartoum, the river passes through six cataracts (rapids) on the way to Aswan. These rapids form when the river encounters igneous rock formations. The cataracts make it extremely difficult to navigate these sections of the river, effectively creating a natural boundary. Once the Nile makes its way to Egypt it splits into two branches -- the Damietta on the east and Rosetta on the west side. This forms the Nile Delta, through which the branches exit Africa and enter the Mediterranean Sea.

Another interesting characteristic of the Nile's course is the Great Bend, a U-shaped bend in course that takes place between the Nile Delta and the Sudanese border. This bend causes the river to suddenly flow west to east, only to then turn around and go back the other way.

A river as mighty as the Nile has obvious effects on the people living nearby. The people of Ancient Egypt certainly prospered, but how does the Nile factor in? Read the next page to find out.

Although m­ost historians and geographers find it difficult to agree on many aspects of the Nile, including its length and source, virtually everyone acknowledges that Ancient Egypt could never have existed without the great body of water. Egypt, known to many as the home of the Great Pyramids, the Great Sphinx and other marvels of the ancient world, isn't ideally located for advanced civilization. Other than the Nile, Egypt is surrounded by tons of sand, which isn't exactly conducive to agriculture and other cornerstones of civilization. Fortunately for the Egyptians, they knew just how to finesse the Nile and its capabilities to turn what would appear to be a barren wasteland into a thriving empire.

A consistent freak act of nature allowed the Egyptians to harness the capabilities of the Nile River. While the majority of Egypt was and still is covered with the aforementioned sand, the river basin next to the Nile boasts wildlife and fertile soils. This is all due to the predictable rise and fall of the Nile's water levels each year, known as inundation (rise) and relinquishment (fall). During the inundation period, which takes place sometime around July, water would rise and fill canals made by Egyptian laborers. Sometime around the end of October, the river would begin to recede, leaving rich silt deposits.

The water that had been collected in the canals and basins during the inundation period was enough to supply nourishment for the crops for the next year. Crops were harvested in June before the return of the floods. The cycle somewhat reliably repeated every year, although it sometimes produced more water than needed, which had negative effects on the crops.

In the early 1900s, several dams were built in southern Egypt in an effort to control the sometimes overzealous flooding. While the dams were able to control the floods to a manageable level, they also decreased the amount of sediment deposits, drastically reducing the fertility of the area. Fortunately for Egyptian farmers, fertilizers are commonplace and they use them to offset the change in land fertility. The system allowed Egyptian farmers to grow a variety of crops, including staples such as wheat and barley. In addition to irrigating the crops and fertilizing the soil, the Nile's inundation period also supplied much-needed drinking water.

The rise and fall of the Nile's life-giving waters inspired the ancient Egyptians to view it as a cycle of death and rebirth. The Egyptians experienced so much success cultivating the Nile that the area became densely populated. Because of this, Egyptian society evolved rapidly developing its own systems of record keeping, accounting and writing (hieroglyphics).

The Nile was not just an agricultural boon for Egypt -- it also was the country's most important roadway, serving as the main thoroughfare to encourage travel and communication capabilities. This function helped to connect outlying portions of Egypt to the capital, enabling trade and communication.

Although the ancient Egyptian society eventually collapsed, the Nile continued to flow. Eventually, Great Britain took control of the Nile basin late in the 19th century, although it later relinquished control in Africa in the 1950s and 1960s.

One of the most daunting possibilities when touring the Nile River is the prospect of coming face to snout with a Nile crocodile. Nile crocodiles typically eat fish, although they're known to deviate from that menu. In fact, they're blamed for the deaths of roughly 200 humans every year [source: reptiles who lay eggs and leave them to fend for themselves.

Hunters nearly caused Nile crocodiles to become extinct by the 1960s, but the species has made a comeback thanks to protection efforts. One crocodile in particular continues to terrorize the people who live along the Rusizi River in Burundi. "Gustave," as locals know him, is credited with the deaths of hundreds of people. The cunning reptile is still on the loose. Gustave tracking enthusiast Patrick Faye claims that his long tenure of terror is a direct result of political and so­cial unrest in the area. According to Faye, the powers that be of the area simply have more important concerns, so for the time being, finding Gustave isn't a priority.

Crocodiles no longer have to share paddling space with hippopotami in the Egyptian portion of the Nile. The hippopotamus is actually native to the area, going far back enough to have been worshipped by Ancient Egyptians. Despite a wide reputation as cute, loveable creatures, the typical hippopotamus is actually quite ferocious and destructive, often known for turning fishing boats upside down and destroying crops.

The Ancient Egyptians believed the animal possessed spiritual powers, in addition to its obvious physical strength. Because of this, the animal became well-represented in Egyptian religion and art. The animal no longer lives in Egypt, although its legacy as a fearsome, destructive creature is unmistakable in the area. Hippos currently call southern sub-Saharan Africa and east central Africa home.

Although they may be tiny, mosquitoes pose a very real threat to residents and visitors to the Nile River area. According to the national Centers for Disease Control and Prevention (CDC), malaria is a very small risk in the highly populated and toured areas of Egypt, so travelers to the region aren't even required to get the malaria vaccine before travel. Mosquitoes and other bugs do still pose other threats, however.

People are another potential hindrance to travelers in the Nile River area. As already mentioned, political and social upheaval have left some areas of Africa in a tumultuous state. In fact, the expedition that determined the ultimate source of the river encountered much hostility in northern Uganda, an area torn apart by war. Ugandan rebels shot one member of the expedition team to death, while the others narrowly escaped.­

Despite Egypt's fairly inhospitable physical environment, it's the second most populated country in Africa -- thanks in large part to the Nile River. In fact, more than 95 percent of Egypt's population lives on the banks of the Nile, despite the fact t­hat the area makes up only 5 percent of Egypt's land mass. As such, the Nile River Valley is one of the most densely populated areas in the world, boasting an average of 3,820 people per square mile [source: National Geographic].

The Nile remains the lifeblood of the countries through which it courses. Farmers produce a wide variety of crops, including citrus fruits, cotton, wheat, sugarcane, legumes and sorghum. Despite a relatively successful agriculture program, the countries through which the Nile flows remain poor and have ever-increasing populations. The Nile Basin Initiative was started in 1999 to help each of these countries utilize the Nile and its benefits.

The Nile is also being used to further hydroelectric power capabilities. Although plans are still underw­ay to continue developing electricity production in the area, several dams have already been built to control flooding and generate hydroelectric power.

The Nile River has also been depicted repeatedly in television programs and major motion pictures, including "The Jewel of the Nile" (1985) and "The Simpsons." The mystique of the Nile River captures the world's imagination.