At the dawn of recorded history, I was there.
Without me your great civilisation would have been
but a lifeless desert. I have witnessed the rise and fall of your kingdoms and the rich
sediments I provided went on to feed an empire. I am both blue and white, sluggish and rapid.
And yet, despite my importance, you did not know from whence I came.
My journey is not just across half a continent, but a journey through centuries of time.
I am the most famous and storied of all the world’s rivers. I am the Nile.
The Nile. It really needs no introduction. The most famous of all rivers, for centuries
it was regarded also as the world’s longest at around 6,650km (4,132 miles).
But this claim has been recently challenged by the Amazon river of South America.
As they are coincidentally so close in length,
it has been difficult to determine which is the longest from estuary to furthest source.
Unlike the mighty Amazon, however, the Nile has a relatively small flow,
due to much of its length being in the Sahara desert that provides no contribution in terms
of rainfall, but rather takes water from the river in evaporation in the desert heat.
Despite its importance in world history, its source remained a mystery until
relatively recently, and vexxed the ancients, mystified at the unusual timing of its floods.
The word “Nile” comes to us via the Latin “Nilus”,
itself believed to have come from the Semitic “Nahal” meaning valley.
The ancient Egyptians called the river “Ar/Aur”, meaning black, alluding to the dark colour of the
sediments carried down the river, in stark contrast to the pale sands of the desert.
Our geographic journey begins at its end – the Nile Delta that flows into the Mediterranean Sea.
Described by Strabo in the 1st Century has having seven main branches, the flow has
since this time been diverted such that there are now only two. Its prototypical triangular shape,
known to the ancient Greeks as early as Herodotus of the 5th Century BC, spawned the geographical
term “delta”, since that Greek letter is in the shape of a triangle. It is here that much
of the sediment of the Nile is deposited, up to 20 meters (75 feet) deep in places,
and constitutes the most fertile soil in Africa. The vast majority of Egypt’s 100 million plus
population is confined to the delta and floodplain of the Nile, as so little rain falls in Egypt that
the population is almost completely dependent upon the river for its vital water supply.
The Nile also acts as a key navigable waterway for the transport of goods as well as people.
The Nile flows as a single river throughout Egypt and Northern Sudan. At various points along the
whole course of the river, there are rapids known as cataracts, and the first of this was where
today’s Aswan Dam is. More on that dam later. The season River Atbara joins the Nile in Northern
Sudan, and during the summer peak, accounts for a fifth of the Nile’s flow. But it’s at Sudan’s
capital, Khartoum, where the two most important tributaries join to the united Nile downstream.
Here the Blue and White Niles join. The two Niles were so named owing to their very different
colours that result from the differing geology that they pass over on their long journeys.
Despite its shorter length, the Blue Nile contributes most of the downstream flow annually
with up to 70% of the peak flow in summer. The Blue Nile has a dramatic descent from the
Ethiopian Highlands at 2,000m (6,000 feet) through a series of gorges over 1000m (4000 feet) deep.
In Ethiopia, the rainy season is in summer, and these seasonal rains are responsible for
the yearly flood of the Nile. As it takes some time for the surge in water to reach downstream,
however, the flood doesn’t peak in Egypt until September and October.
The White Nile and its tributaries is much longer, but the flow is more constant.
It delivers 80% of the total Nile flow at the lowest point during April/May but is dwarfed
by the Blue Nile in summer, delivering only 10% of the total flow in August. The White Nile, by name,
ends at the wetland of South Sudan, known as The Sudd. Here the land is so flat that the river
breaks up into hundreds of channels across tens of thousands of square kilometers. The wetland acts
as a barrier to navigation owing to the mass of vegetation that choke the multitude of streams.
Beyond the Sudd, the river becomes the Mountain Nile or Al-Jabal river,
rising via a series of rapids to Lake Albert on the borders of Uganda and Congo. From Lake
Albert the river is known as the Victoria Nile, since this last major segment is
sourced by the giant Lake Victoria, the world’s second largest freshwater lake.
Because of its size, the lake is sourced by many rivers, with none standing out among the others
in terms of length or flow, and so the Nile as an identifiable river ends with this lake. The
most distant source of the Nile’s waters is still not clear, although a recent search has identified
that the headwaters of the Kagera and Ruvubu Rivers in Burundi are the most likely location.
These lands that bore the source of the Nile, in the heart of the East African highlands,
were a complete mystery to outsiders, not just in ancient times, but throughout the medieval
and later periods. The source of the Nile did not enter recorded history until only 160 years ago,
a remarkable fact considering the river’s importance throughout history.
The waters of the Nile and their dark rich sediments provided possibly the earliest
irrigation in human agriculture. It’s constant year-round flow of water, in combination with
year-round heat and strong sunlight meant intensive agriculture was possible in Egypt making
it unique within the Mediterranean world. These waters flooded during late summer, depositing
their rich sediments across a wide area. The timing of the flood was a phenomenon at odds
with the ancient Greek and Roman experience of all other rivers being in flood during winter – peak
rains in the Mediterranean occur in the cooler season. We know today that this summer Nile flood
is due to the monsoonal pattern of rain over the headwaters of the Blue Nile in Ethiopia, which
receives most of its rain in summer, the opposite pattern of rainfall to that of the Mediterranean.
In ancient scripture, the Nile played a key role in the Book of Exodus of the Bible,
with its waters carrying the infant Moses in a basket of reeds.
Moses would later lead the Israelites from slavery within Egypt, but only
after Pharoah relented, following the ten plagues visited upon the land.
It is believed that the ancient Egyptians had knowledge of the Nile as far as its confluence
at today’s Khartoum, and possibly as far as Lake Tana in Ethopia up the Blue Nile.
This area of the Upper Nile, known as Nubia, was home to various kingdoms with the Kushites being
the most successful, reaching a peak in the 8th Century BC, but continuing until the end
of antiquity with their capital of Meroë on the banks of the Nile just north of today’s Khartoum.
Egypt was the last Mediterreanean kingdom to conquered by the Roman Empire in 30BC, and was
prized due to it being the most fertile region known to them, owing to the waters of the Nile.
In this period Egypt became known as the breadbasket of the empire due to its
prodigious harvests, so it could be said that the waters of the Nile, originating within the heart
of East Africa, fed much of the Roman Empire. The source of these incredibly important waters
became an obsession for many Romans, and one of these was that most famous of emperors, Nero.
In 66AD he ordered an expedition up the Nile to find its source.
The journals of this expedition are recorded by Pliny the Elder and Seneca the Younger.
They agree that the weed-choked channels of the Sudd acted as a barrier to the
expedition’s progress, although there is a curious reference to a waterfall flowing
through two pillars to the south, which would suggest that somehow they’d gone beyond the flat
lands of the Sudd into the Mountain Nile, but more likely that they’d either heard tales of
such geography from those they met along the way or possibly had invented them entirely.
In 150AD, the great Egyptian geographer Ptolemy described the source of the Nile as belonging
to the Mountains of the Moon, apparently from an earlier report by the supposed merchant Diogenes,
who had claimed to have found the source within a series of lakes nestled among snowy peaks.
Now, sharp eyed geographers among you would know these to be the Rwenzori mountains on
the border of Uganda and Congo, close to the actual sources of the Nile established today.
This would be the cause of great excitement, were it not for the fact that Ptolemy’s
Mountains of the Moon were much further north, an imagined chain of mountains
running west from Ethopia across Sudan, which in fact do not exist as Sudan is largely flat.
This was the established view of the Source of the Nile for the next seventeen centuries.
In the 1800s, the British Empire continued to extend itself around the world, with Africa being
no exception. Egypt, Sudan and Kenya had fallen to the British at various times in this century,
and the Royal Geographic Society of London saw that this situation could finally resolve the
matter of the Source of the Nile through a series of expeditions into the Terra Incognita of the
“Dark Continent”. The explorers John Hanning Speke and Richard Burton were the first Europeans to see
Lake Victoria in 1858, travelling up from the East African coast at Zanzibar rather than attempting
passage down the Nile through the impenetrable Sudd. The explorers both claimed to have confirmed
that Lake Victoria was the source of the Nile, and later had a very public falling out over
the matter. But it was Speke, without Burton in 1862 that correctly located the outlet of
the Nile on the northern shore of Lake Victoria, and linked the famous river and lake in that way.
As mentioned earlier, of course, we know Lake Victoria to be fed by many headwaters, and many
expeditions have been conducted in the time since Speke, to try and find the most distant source,
with the Kagera and Ruvubu Rivers in Burundi currently thought to be the furthest. But the
discovery of Lake Victoria appeared to have settled the burning question for most
as to the Source of the Nile, the longest running mystery in geographical history.
The most significant development in modern times to affect the Nile was the building of
the Aswan High Dam in southern Egypt that began in 1960. The dam’s main purpose was to regulate
the amount of water passing downstream, which used to vary considerably year upon
year – too much led to devastating floods, too little to a poor harvest and famine.
Upon its completion in 1970, the millenia of annual floods in Egypt finally came to an end,
as the seasonal flood from the Blue Nile is absorbed within the 168 cubic km (40 cu miles)
capacity of Lake Nasser formed upstream of the dam. Due to its location within the Sahara desert,
however, the lake loses between 10 and 30% of water annually through evaporation.
Another benefit is the dam providing 2GW of power through its hydroelectric turbines.
Another, larger dam on the Blue Nile in Ethiopia is currently in the filling phase, and has been
the cause of considerable tensions between this country and Egypt. Construction of the GERD (Grand
Ethiopian Renaissance Dam) began in 2011 and when completed, will provide 5GW of much needed
power to Ethiopia, and could advance economic development within that country considerably.
Egypt has disrupted funding of the dam from international partners, resulting in delays
in construction and claims the dam will reduce the flow downstream. While this is certainly true
during the filling phase, it is unclear how this would be the case during operation post-filling.
So, this greatest of rivers, spanning millenia of recorded history, even today writes a new page
of history with a dam that could transform the country whose rains once produced that
seasonal flood so far downstream, that flood which lead to the development of that great
civilisation and prompting questions across the millenia over the mystery of its faraway source.
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