A website launched under the leadership of UKZN’s Environmental Fluid Mechanics Lab (EFML) Co-Director, Dr Justin Pringle, is designed to provide real-time guidance to beachgoers in Durban regarding the safety of water at popular beaches for swimming.

This comes in the wake of increasing sewage pollution along the coastline, with Durban’s beaches often demonstrating critically high levels of Escherichia coli (E. coli), a harmless bacteria found in the guts of healthy people and animals that indicates the presence of faecal matter in the water. While E. coli decays rapidly in a marine environment, making it a less-than-ideal indicator, harmful pathogens from sewage pollution may still be present and threaten human and aquatic health, causing diseases including cholera, dysentery, typhoid fever, and more. This also poses risks to Durban’s economy which relies heavily on tourism. Pollution has been exacerbated by ageing and vandalised water infrastructure and the April 2022 floods in KwaZulu-Natal.

In response to these challenges and in the interest of providing scientific information to the public, Pringle launched Woz’Olwandle, meaning “come to the sea” in isiZulu. Based on a tool developed for Los Angeles beaches in the United States (US), the Beach Report Card, the Woz’Olwandle website features information synthesised by a fluid dynamics computer model that was developed by UKZN’s Professor Derek Stretch (who heads up the EFML with Pringle) and alumnus Mr Dave Mardon, now an Associate at Water Environment Ltd in the United Kingdom, in the early 2000s.

This model was repurposed to process several data and estimate the concentrations of E. coli at six central Durban beaches over 24 hours, using a key of three “smiley” icons in green, orange, or red to indicate whether conditions are “good”, “acceptable”, or “poor”. The website is hosted on a US server to prevent outages caused by ongoing load-shedding in South Africa.

Some of the conditions the model considers that affect pollution levels include rainfall and wind, which influence how pathogenic bacteria are mixed and dispersed close to the shoreline; as well as the decomposition rates of bacteria in sunlight and seawater. It uses daily weather and other data from the Global Forecast System which focuses on earth observation, a weather station at uShaka Beach, and results from Talbot Laboratories which regularly gathers and tests water samples.

Pringle hopes that the tool will not only provide the most up-to-date information for people to use in deciding if and where to swim, but also spark discussion about the problem of sewage pollution and potential solutions. Real-time information is important because other information provided on water quality takes time to gather, analyse, and release, often making it out of date by the time users receive it.

The Woz’Olwandle website has already attracted attention for its efforts, including features in the Daily Maverick, The Witness, East Coast Radio, and Lotus FM. The site has been used by three and a half thousand people over the past month, with visits from South Africa, the United States of America, the United Kingdom, China, Australia, and Germany.

The EFML, which has a strong reputation for applying its expertise to issues ranging from coastal engineering and renewable energy to climate change and the spread of the SARS-CoV-2 virus, hopes that the academic and societal collaboration that made Woz’Olwandle possible will also enable its expansion to include other beaches in Durban and eventually the whole country, as well as identify problem areas in terms of sewage pollution within the eThekwini Municipality.

The latter initiative already has plans in place and researchers are attached to mobilise UKZN’s cellular biology, genomics, marine geology, ecotoxicology, and environmental fluid mechanics expertise to identify the sources of sewage pollution.

Words: Christine Cuénod

Image: Supplied