Page 14 - Discover Botswana 23rd Edition 2023

The longevity of this ecosystem is quite remarkable. It is reliant on a delayed flooding effect caused by the long distance the source water needs to travel. During our late summer months, rainfall spreads across southern Africa, and falls on the Okavango system as well as the catchment area in the Angolan highlands. The local rainfall is enough to fill up outlying waterholes and trigger trees and grasses into an abundance of life. However, although it helps, the rainfall alone is not enough to sustain water levels in the delta. As the rains slow down and we head into a dry winter, water that has been travelling close to 1700kms finally reaches the upper Okavango and starts the slow process of filling up the wetland. It takes approximately 2-3 months for the water to arrive from Angola, once it reaches the flat sandbox a further 3-4 months is needed for it to create its annual masterpiece – the Okavango. This delayed response is truly what allows the ecosystem to stay alive. If the rain and floods occurred at the same time the system would flood, and then not see water again for close to 9 months, just too long to keep water-reliant plants and animals alive.
So, fast forward a few months and we are now in late November. Thunderous clouds rent their anger on the land with torrential downpours. Those parched fingers regain fluttering green leaves and once again grasses grow to nod in the breeze. Vibrant life returns to the ecosystem, but the water levels are still dropping. Fast forward another few months to April and finally, after its long, long journey, fresh water floods into the Okavango. The Delta expands in size by up to 2 thirds and waterways that have been bone dry for months suddenly feel the cool, watery kiss of the flood. With remarkable speed life follows the water; fish and amphibians tumble down to take advantage of insects now out of their element. Within days, the sharp cries of kingfishers, herons, eagles and egrets follow. A week or two longer and dormant vegetation has come alive to flush the new channels with green. Wildlife and humans alike rejoice in this miracle, for without it survival would be a very different game.
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Right: An Elephant bull wades across the Okavango’s Boro channel. During the dry months these giants rely on the nutrient rich aquatic vegetation along the banks of the permanent channels. Once the rains arrive, they disappear into the vast Mophane woodlands surrounding the Delta.