The Victoria Falls or Mosi-oa-Tunya
(Tokaleya Tonga: the Cloud that Thunders; note that the 'i' is
silent) is a waterfall located in southern Africa on the Zambezi River between the countries of Zambia and Zimbabwe.
Naming
David Livingstone, the Scottish missionary and explorer, is believed to have
been the first European to view the Victoria Falls — which he did from what is
now known as 'Livingstone Island' in Zambia, the only land accessible in the
middle of the falls. David Livingstone gave the falls the name 'Victoria Falls'
in honour of Queen Victoria, but the indigenous name of 'Mosi-oa-Tunya' — literally
meaning the 'Cloud that Thunders' — is also well known. The World Heritage List recognizes both names.
Size
While it is neither the highest nor
the widest waterfall in the world, it is claimed to be the largest. This claim
is based on a width of 1,708 metres (5,604 ft) and height of 108 metres
(354 ft), forming the largest sheet of falling water in the world. The
falls' maximum flow rate compares well with that of other major waterfalls
For a considerable distance upstream
from the falls, the Zambezi flows over a level sheet of basalt, in a shallow valley bounded by low and distant sandstone hills. The river's course is dotted with numerous
tree-covered islands, which increase in number as the river approaches the
falls. There are no mountains, escarpments, or deep valleys which might be expected to create a
waterfall, only flat plateau extending hundreds of kilometres in all directions.
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| The mighty Victoria falls |
The falls are formed as the full
width of the river plummets in a single vertical drop into a transverse chasm
1708 metres (5604 ft) wide, carved by its waters along a fracture
zone in the basalt plateau. The depth of the chasm, called the First Gorge,
varies from 80 metres (260 ft) at its western end to 108 metres
(354 ft) in the centre. The only outlet to the First Gorge is a 110 metres
(360 ft) wide gap about two-thirds of the way across the width of the
falls from the western end, through which the whole volume of the river pours
into the Victoria Falls gorges.
There are two islands on the crest
of the falls that are large enough to divide the curtain of water even at full
flood: Boaruka Island (or Cataract Island) near the western bank, and
Livingstone Island near the middle — the place that David Livingstone first saw
the falls from in Zambia. At less than full flood, additional islets divide the
curtain of water into separate parallel streams. The main streams are named, in
order from Zimbabwe (west) to Zambia (east): Devil's Cataract (called Leaping
Water by some), Main Falls, Rainbow Falls (the highest) and
the Eastern Cataract
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‘The Cloud that Thunders’, rainy season,
1972 ... and dry season, September 2003
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Size and flow rate of Victoria Falls with Niagara
and Iguazu for comparison
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Parameters
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Victoria Falls
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Height in meters and feet:
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108m
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360 ft
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51 m
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167 ft
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64–82 m
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210–269 ft
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Width in meters and feet:
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1,708 m
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5,604 ft
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1,203 m
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3,947 ft
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2,700 m
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8,858 ft
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Flow rate units (vol/s):
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m³/s
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cu ft/s
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m³/s
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cu ft/s
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m³/s
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cu ft/s
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Mean annual flow rate:
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1,088
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38,430
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2,407
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85,000
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1,746
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61,600
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Mean monthly flow — max:
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3,000
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105,944
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— min:
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300
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10,594
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— 10yr max:
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6,000
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211,888
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Highest recorded flow:
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12,800
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452,000
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6,800
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240,000
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12,600
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444,965
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Notes: See references for
explanation of measurements.
For water, cubic metres per second = tonnes per second. Half the water approaching Niagara is diverted for hydroelectric power. Iguazu has two drops; height given for biggest drop and total height. 10 falls have greater or equal flow rates, but are not as high as Iguazu and Victoria Falls. |
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The Zambezi basin above the falls
experiences a rainy season from late November to early April, and a dry season the rest of the year. The river's annual flood season is February to May with a peak in April,[4] The spray from the falls typically
rises to a height of over 400 metres (1,300 ft), and sometimes even
twice as high, and is visible from up to 50 k away. At full moon, a
"moonbow" can be seen in the spray instead of the usual daylight
rainbow. During the flood season, however, it is impossible to see the foot of
the falls and most of its face, and the walks along the cliff opposite it are
in a constant shower and shrouded in mist. Close to the edge of the cliff,
spray shoots upward like inverted rain, especially at Zambia's Knife-Edge
Bridge.[5] As the dry season takes effect, the
islets on the crest become wider and more numerous, and in September to January
up to half of the rocky face of the falls may become dry and the bottom of the
First Gorge can be seen along most of its length. At this time it becomes
possible (though not necessarily safe) to walk across some stretches of the
river at the crest. It is also possible to walk to the bottom of the First
Gorge at the Zimbabwean side. The minimum flow, which occurs in November, is
around a tenth of the April figure; this variation in flow is greater than that
of other major falls, and causes Victoria Falls' annual average flow rate to be
lower than might be expected based on the maximum flow.
Victoria Falls is roughly twice the
height of North America's Niagara Falls and well over twice the width of its Horseshoe Falls. In height and width Victoria Falls is rivalled only by
South America's Iguazu Falls. See table for comparisons.
The Victoria Falls Gorges
The whole volume of the Zambezi
River pours through the First Gorge's 110-meter-wide (360 ft) exit for a
distance of about 150 meters (500 ft), then enters a zigzagging
series of gorges designated by the order in which the river reaches them. Water
entering the Second Gorge makes a sharp right turn and has carved out a
deep pool there called the Boiling Pot. Reached via a steep footpath
from the Zambian side, it is about 150 metres (500 ft) across. Its
surface is smooth at low water, but at high water is marked by enormous, slow
swirls and heavy boiling turbulence. Objects—and humans—that are swept over the
falls, including the occasional hippo, are frequently found swirling about here
or washed up at the north-east end of the Second Gorge. This is where the
bodies of Mrs Moss and Mr Orchard, mutilated by crocodiles, were
found in 1910 after two canoes were capsized by a hippo at Long Island above
the falls.
The principal gorges are (see
reference for note about these measurements):
- First Gorge: the one the river falls into at Victoria Falls
- Second Gorge: (spanned by the Victoria Falls Bridge), 250 m south of falls, 2.15 km long (270 yd south, 2350 yd long)
- Third Gorge: 600 m south, 1.95 km long (650 yd south, 2100 yd long), containing the Victoria Falls Power Station.
- Fourth Gorge: 1.15 km south, 2.25 km long (1256 yd south, 2460 yd long)
- Fifth Gorge: 2.55 km south, 3.2 km long (1.5 mi south, 2 mi (3.2 km) long)
- Songwe Gorge: 5.3 km south, 3.3 km long, (3.3 mi south, 2 mi (3.2 km) long) named after the small Songwe River coming from the north-east, and the deepest at 140 m (460 ft), the level of the river in them varies by up to 20 meters (65 ft) between wet and dry seasons.
Formation
Satellite image showing the broad Zambezi falling into the
narrow cleft and subsequent series of zigzagging gorges (top of picture is
north).
The recent geological history of
Victoria Falls can be seen in the form of the gorges below the falls. The basalt plateau over which the Upper Zambezi flows has many large
cracks filled with weaker sandstone. In the area of the current falls the
largest cracks run roughly east to west (some run nearly north-east to
south-west), with smaller north-south cracks connecting them.
Over at least 100,000 years, the
falls have been receding upstream through the Batoka Gorges, eroding the sandstone-filled
cracks to form the gorges. The river's course in the current vicinity of the
falls is north to south, so it opens up the large east-west cracks across its
full width, then it cuts back through a short north-south crack to the next
east-west one. The river has fallen in different eras into different chasms
which now form a series of sharply zig-zagging gorges downstream from the
falls.
Ignoring some dry sections, the
Second to Fifth and the Songwe Gorges each represents a past site of the falls
at a time when they fell into one long straight chasm as they do now. Their
sizes indicate that we are not living in the age of the widest-ever falls.
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| Victoria falls |
The falls have already started
cutting back the next major gorge, at the dip in one side of the "Devil's
Cataract" (also known as "Leaping Waters") section of the falls.
This is not actually a north-south crack, but a large east-northeast line of
weakness across the river, where the next full-width falls will eventually
form.
The Victoria Falls Bridge initiates
tourism
European settlement of the Victoria
Falls area started around 1900 in response to the desire of Cecil Rhodes' British South Africa
Company
for mineral rights and imperial rule north of the
Zambezi, and the exploitation of other natural resources such as timber forests
north-east of the falls, and ivory and animal skins. Before 1905, the river was
crossed above the falls at the Old Drift, by dugout canoe or a barge towed across with a
steel cable. Rhodes' vision of a Cape-Cairo railway drove plans for the first bridge
across the Zambezi and he insisted it be built where the spray from the falls
would fall on passing trains, so the site at the Second Gorge was chosen. See
the main article Victoria Falls
Bridge
for details. From 1905 the railway offered accessible travel to whites from as
far as the Cape in the south and from 1909, as far
as the Belgian Congo in the north. In 1904 the Victoria Falls Hotel was opened to accommodate visitors
arriving on the new railway. The falls became an increasingly popular
attraction during British colonial rule of Northern Rhodesia (Zambia) and Southern Rhodesia (Zimbabwe), with the town of Victoria Falls becoming the main tourist centre.
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