The Okavango Delta is an incredibly dynamic ecosystem. Its fluctuating water levels cause vegetation and habitats to adapt accordingly in very short time spans.
The Delta has historically always experienced wet and dry spells, which last roughly 30 years each. We are currently in the tail end of a wet cycle and the exceptionally low rainfall beginning of this year is not unusual according to historical data. Tentative weather predictions are looking positive with better rains this year and a bigger flood in 2020.
The current drier conditions we are experiencing are, almost counter intuitively, not bad news. During our exceptionally high flood levels in the early 2000s, large tracts of the Delta were flooded for longer periods of time. This meant that the grazing that occured on the floodplains once the water receded was no longer available for the herbivores and the nutritious grass was replaced by unpalatable sedges (types of mostly perennial but sometimes annual herbs that have a ‘tuft-like’ appearance). This has meant that herbivore numbers actually declined over this period even though the Delta was at its fullest and prettiest.
This year’s exceptionally low floods mean a lot of those floodplains have become accessible and the sedges will die back so that grass can grow again, making the land once again suitable for grazing. The herbivore populations will increase thanks to the extra food, which in turn positively affects the predators. So, while there may not be picture-book Delta water activities everywhere, there has been exceptional game viewing instead.
The upper or northern Delta has received its usual annual floods, albeit in lesser volumes, which means that conditions there haven’t changed as much.
The lower or southern Delta is affected the most due to the lack of flooding but the newly available grazing will only enhance the game-viewing experience. The reason for this distinct shift in flooded areas between the upper and lower Delta is most likely directly related to the big earthquake Botswana experienced in 2017. Due to the sandy substrate the Delta lies on, even a small shift is enough to divert water flow.
This cycle should see an overall improvement in the amount of grass available as the water-loving sedges die down, leading to the exciting game viewing we all enjoy so much.