A water quality model has come to the rescue of many avid beachgoers in Durban. The model, designed 20 years ago, was repurposed and launched last month by University of KwaZulu-Natal (UKZN) engineering researcher and lecturer, Dr Justin Pringle. A green smiley face tells you when it’s good to go for a swim, an orange smiley face says it acceptable to go frolic in the ocean, but the red smiley face is a definite no.
Dr Pringle, UKZN’s Environmental Fluid Mechanics Lab (EFML) co-director, launched a website Woz’Olwandle – meaning “come to the sea” in isiZulu. It’s designed to provide real-time guidance to Durban beachgoers relating to the safety of water at swimming beaches.
Dr Pringle said this comes in the wake of increasing sewage pollution along the coastline. Durban’s beaches often have 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.
“E coli decays rapidly in a marine environment, making it a less-than-ideal indicator. However, 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,” said Dr Pringle.
He said the model is based on a tool developed for Los Angeles beaches in America. The Woz’Olwandle website, he said, features information synthesised by a fluid dynamics computer model that was developed by UKZN’s Professor Derek Stretch (who heads up the EFML with Dr Pringle) and alumnus Dave Mardon, in the early 2000s. Mr Mardon was a student then, he now is an associate at Water Environment Ltd in the United Kingdom.
“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,” said Dr Pringle.
He said they want to extend this model to Umhlanga, the South Coast and the rest of the country. So far Point, South, uShaka, North, Battery and Country Club beaches are being monitored. The model can also identify problem areas of sewage pollution within the eThekwini Municipality.
“Beach water quality is a problem around the world – the West Coast in the USA has vigorous monitoring, and we want to do the same here. We have partnered with Talbot Labs. Cellular biologists teamed up to develop the model further and better improve the accuracy of the results,” said Dr Pringle.
Some of the conditions the model considers that affect pollution levels include rainfall and wind. They influence how pathogenic bacteria are mixed and dispersed close to the shoreline. It also monitors the decomposition rates of bacteria in sunlight and seawater, said Dr Pringle. 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 gather and tests water samples.
Dr Pringle is confident this model will provide the most up-to-date information for people to use in deciding whether to go swimming or not. However, it also sparks 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,” he said. “The Woz’Olwandle website has already attracted attention for its efforts. In the first month more than 5000 people used the site. It has been especially useful for the surfing community who check out the website before they head out surfing.”
For more information go to www.wozolwandle.com