Okavango - the biggest drought in 90 years?
The men with the long white beards who have been around almost as long as the delta itself are saying this is the driest the delta has been in 90 years. Is this true? We have always said that the Okavango Delta looks like a massive hand imprinted on the flat, dry Kalahari sand. Well, looking at 2019 it looks more like a herpetologists hand after too many cytotoxic bites.
Why did some fingers survive and the others not. On a recent exploratory trip to the northern Okavango we encountered water gushing through the channels that feed the rivers to the north of Chief's Island. Some say this was done by lodge operators who opened channels to bring water to their area of the delta.
However, after inspecting the channel that was implicated in the theft of the water by drone, there is no evidence of any tampering. The water is gushing down this channel and it is easy to understand why it seems suspicious. The Okavango does not gush.
A more plausible theory is that the earthquake that shook Botswana on the 3rd of April 2017 has shifted the underlying geology. With such a thick cushion of sand it can take time for the full extent of movement of the bedrock to fully reflect on the surface. With such a narrow gradient, minor underground shifts can have pronounced consequences. The shift in water to the rivers north of Chief's Island however has been going on before the big shake of 2017. This has been demonstrated by the increased extent of the Khwai River over the past 20 years.
The ultimate culprit however, is the dramatically reduced rainfall. Both the Okavango and the catchment for the source rivers that feed the delta had shockingly low rainfalls. With just under a third of our usual summer rainfall, the dismal flood arrived into a parched Okavango.
So, where to from here? Well, the El Nino conditions that have been driving the drought are slowly alleviating. Meteorologist expect that the 2019/2020 rain season will start of with below average rainfall but with the latter half of the rain season having average to possibly above average rainfall. Predicting the weather for tomorrow can be difficult enough so understand that these long-term forecasts are based on a lot of science that is plagued by an infinite number of variables. The Okavango is a river of trends. Even with a great rain season and an awesome flood next year, it will take several good years in a row to get back to the delta we have all come know over the past 15 years.