Page 41 - Discover Botswana 25th Edition - 2025

DISCOVER BOTSWANA 25TH EDITION 41
The “Angolan Highlands Water Tower” is the largest
water tower on the African continent and the prime
reason we have an Okavango Delta.
This hydrological system sustains Africa’s largest wetland wilderness,
the Okavango Delta. In 2023, Dr Mauro Lourenço and researchers
supported by the Nkashi Trust in Botswana, published a landmark
paper in the journal: Environmental Monitoring and Assessment - the
first-ever description of this extraordinary water tower structure in the
Angolan Highlands. This study focused on the important influence of the
water tower on the flood pulses of the Cubango and Cuito Rivers into the
Okavango Delta during the dry season. It demonstrated that, based on the
presence of source lakes and vast peatlands, the Delta is far more resilient
to climate change than previously believed.
The two major tributaries of the Okavango Delta have overlapping
rainy seasons and adjacent headwaters, but their flood waters reach the
Delta at different times. The Cubango River has a longer, steeper gradient,
so its waters run faster over compacted soils and reach the Okavango Delta
between January and March, feeding the first flood pulse. The meandering
Cuito River runs through extensive spongy peatlands and feeds the second
pulse in April / May. Very significantly, this flood pulse sustains the Delta
through the dry season.
The Delta is in the middle of the semi-arid Kalahari Desert where 98%
of water inflows are lost to evaporation and transpiration from vegetation.
The source lakes and peatlands that sustain the flows of the Cuito River,
the Delta’s lifeline, are in the eastern Angolan Highlands, in a landscape
called by the local Luchazi people Lisima lya Mwono, the “Source of Life”.
Without the water tower, the Okavango Delta would
be as dry as the Makgadigadi Pans.
The importance of the water tower in sustaining the Okavango Delta
and its precious biodiversity cannot be overemphasised, yet it faces many
threats - increasing human encroachment being the greatest. Angola’s
population is likely to double, to 72 million by 2050, putting huge
pressure on the Cubango and Cuito Rivers. This situation is exacerbated
by climate change, as scientists predict less rainfall over the Okavango
Delta, and more over the water tower, making the Delta more dependent