Fragility of Botswana’s Okavango Delta must be managed
The Okavango Delta in northern Botswana is a mosaic of water paths, floodplains and arid islands. The delta sits in the Okavango river basin, which spans three African countries: Angola, Namibia and Botswana.
Because it’s an oasis in a semi-arid area, it hosts a rich array of plants and attracts a huge variety of wildlife.
As a unique ecosystem, in 2014 it was placed on Unesco’s world heritage list and it is an iconic tourist destination, which generates 13% of Botswana’s GDP.
But it’s a fragile natural area. It’s controlled by deformations of the Earth’s crust over a long time (thousands to millions of years) and by annual water flows and evaporation. The size of the flooded delta from year to year varies between 3 500km² and 9 000km² because of weather fluctuations which control its water supply.
The history of the Okavango
Delta’s waterways and floodplains tells us the interplay between geology, water and plants makes the delta resilient, but vulnerable.
Some imminent changes are expected that are of concern.
One is higher temperatures, which will boost evaporation and transpiration. Another is the pumping of water for irrigation in Namibia. Both of these changes will reduce the water needed to sustain the delta’s floodplains.
The Okavango Delta is a generally flat area which is under constant change with phases of flooding and drying.
A variety of geographical and natural processes have formed it and sustain it.
It’s in a depression which was created by fault lines cutting the Earth’s surface. This means water flows into it.
The water supply comes from the Cubango and Cuito rivers in Angola. This reaches the delta between March and June and peaks in July. There’s also local rainfall in the Okavango area from November to February (about 450mm a year) which adds to this.
About 98% of the water that goes into the delta is eventually lost through evaporation and plant transpiration.
The Okavango Delta is continually being shaped by complex interactions of natural processes. If something happens to change the balance of these processes, it could destabilise the system.
Murray-Hudson, senior research fellow, Okavango Research Institute, University of Botswana
Dauteuil, Directeur de Recherche au CNRS, Université Rennes 1
– Republished from TheConversation.com