Scientists called in as wind disrupts fruit exports in Cape Town

Scientists called in as wind disrupts fruit exports in Cape Town 

Extreme winds in the Cape Town harbour in South Africa is a concern

The CSIR-hosted Alliance for Collaboration on Climate and Earth Systems Science (ACCESS), along with other CSIR researchers and partners, are assessing the economic impacts of wind disruptions, and they are supporting the Transnet National Port Authority (TNPA) and its clients with short- and long-term wind predictions.

At the peak of the fruit picking and packing season, it is normal for Cape Town’s gusty summer southeaster to swirl over and around Table Mountain and Devil’s Peak. It is normal for that strong Cape Doctor wind to then blow down to the bay, focusing, as if through a lens, onto container ships and cranes moving in the port.

Extreme winds in the harbour

It is not normal, however, for the port to experience extreme winds that are more frequent and intense than before. “This is our concern, especially when demand for marine services in the port is increasing,” says Dr Neville Sweijd, the director of the ACCESS programme.

If these amplified harbour winds exceed about 80 kilometres per hour, port operations need to shut down to avoid safety risks from swinging containers and the potential collapse of cranes.

Sweijd says such wind disruptions are causing logistical headaches and financial losses for fruit exporters. Over the last few years, the Port of Cape Town lost, on average, 1 200 hours of operational time annually due to extreme wind disruption.

“Occasionally, fruit companies have to put their fruit on a truck and get it to Durban so that they can get it to their market on time,” says Sweijd.

“We provide them essentially with weather parameters that inform their port operations,” says CSIR engineer, Vuyo Ndayi, who specialises in ocean monitoring in ports. He says the CSIR’s wind anemometers and sensors provide wind speed, wind direction and wind gust data that allow for hourly and daily operational decision making.

Planning around wind delays

“We need to get a good handle on understanding the wind, how it will trend going forward, and what measures we can actually then put in place to try to reduce the effects on port operations,” says Magenthran Ruthenavelu, technical director at TNPA.

Ruthenavelu adds that the research will inform potential changes or additions to the port layout and structures to divert wind away from the operational area of the terminals.

Zelde Kennedy, spokesperson for major fruit exporter Fruitways, says the data will also help exporters plan around anticipated wind delays. “It will definitely have an impact on our cost, and I think it will be better for the whole industry,” she says.

More frequent extreme weather events

Sweijd says extreme wind disruption of fruit exports is an example of how the negative impacts of climate variability and change manifest in day-to-day life.

“Climate change is not some phenomenon of the future and it’s not something that happens on average – it impacts people at the weather scale, not just at the long-term climate scale. It impacts them with extreme weather events, not as an average,” he says.

“We’re seeing a trend in the extreme events that are happening more frequently and that are happening with longer duration. They are more intense with bigger magnitude,” says Sweijd.

For the windy Cape Town port, Ndayi says long-term predictions and climate modelling will try to answer the question of how the wind will change. “Is it going to become worse? Is it going to become better? Are we going to see it outside of the spring and summer months, and how is that going to affect how things are run in the port?”

The project is supported by the National Research Foundation and the Belmont Forum.”

Scientists called in as wind disrupts fruit exports in Cape Town