To The Victoria Falls
Victoria Falls Facts and Figures
The Victoria Falls (located approximately 17.925'S 25.855'E) are formed on the Zambezi River, approximately half-way along its long journey to the sea and the dividing boundary between Zambia and Zimbabwe.
The Victoria Falls are 1,708 meters wide, dissecting the entire width of the river, and when the river is in full flood is described as the largest curtain of falling water in the world. Substantially larger than North America's Niagara Falls, the Victoria Falls are only rivalled by the Iguaza Falls in South America, which are 2,700m wide and 80m high, but are however divided into over 270 separate 'smaller' falls and cataracts. At 10.8 km wide, the Khone Falls in Laos are the world's widest, but this is broken by many islands. The highest are Angel Falls (locally known as Churun-Meru) in Venezuela.
Islands along the crestline of the Victoria Falls, the largest being Cataract (or Boaruka) and Livingstone Islands, divide the curtain of water into sub-sections. At the most western end, the Devil's Cataract or Leaping Water (only 35 metres wide) is the lowest point of the river, then the Main Falls (approximately 460m wide), where the main flow of the river falls even during low water, and finally Horseshoe (about 530m wide), then Rainbow and Eastern Falls form the remaining and longest sections, often dry of water during low season.
The huge seasonal, and annual, variation in the rainfall of the region (most falling in the months from November to March), greatly affects the volume of water flowing over the Victoria Falls. There is also an appreciable delay in rainwater reaching the Victoria Falls as it works its way through the rivers vast upper catchments and upper reaches (see The Zambezi River section for more information).
Records of water levels from the above the Victoria Falls have been taken since the establishment of the Victoria Falls Hydrological Station in 1907. These indicate lower than average years for 1907-1946, above average for the years 1947-81, and again below normal for 1982-97. A major flood of 1958, during the construction of the Kariba Dam, followed heavy rains in the upper catchment and also the local catchment below Victoria Falls. In magnitude it was equivalent to the '1 in 100 year flood', which in turn is roughly half the probable maximum flood 1 in 1,000 year flood (Gupta, 2007).
Flow measurements are also carried out at the Victoria Falls, where the highest maximum flow of 10,000 cubic metres per second was recorded in March 1958 (during construction of the dam). The lowest flows recorded to date at Victoria Falls were during the 1995/96 season which had an annual mean flow of 390 cubic metres per second, against a Long Mean Annual flow at Victoria Falls of 1,100 cubic metres per second.
As part of the studies for the development of the Batoka Dam average flow of water over the Victoria Falls were calculated with information data from the Victoria Falls Hydrological Station from 1907-92. The yearly mean average was assessed to be 1182m3/sec, with average mean flow in the low season (July-Jan) of 490m3/sec and high season (Feb-June) of 2153m3/sec.
Mean annual flow for the Zambezi River as measured at the Victoria Falls Hydrological Station (1907-2002) [From Gupta, 2007]
At its highest point, in March/April, it is estimated that 500 million litres of water per minute flow over the Victoria Falls. During the dry season, it can be as low as 10 million litres. The 1958 flood of the Zambezi saw the Falls reach record volumes of over 770 million litres per minute. Only the Iguazu Falls rivals the Victoria Falls in these terms (its record being only slightly less, at 750 million litres per minute) but a dam has decreased this, although the Boyoma Falls (formerly Stanley Falls) in Congo (formerly Zaire) has a higher total annual flow.
The spray created from the Victoria Falls, forced up and out from the gorge, rises some 400m to 800m into the air, and can be seen from 30 to over 60 kilometres away, and is best witnessed in the cool hours of the early morning. As the water droplets condense they fall as localised rain, creating rainbows and supporting the rainforest on the opposite side of the gorge, which is especially well developed opposite the Main Falls on the Zimbabwe side.