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New ‘poo predicter’ tells swimmers if water’s safe at Durban beaches

New ‘poo predicter’ tells swimmers if water’s safe at Durban beaches
Though beach water was rated as ‘good’ early on 8 March at uShaka Beach, the real-time model predicts a deterioration to ‘poor’ early on 9 March.
Tony Carnie
By Tony Carnie
8 Mar 2023
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Science boffins at the University of KwaZulu-Natal will launch a new website on Thursday, 9 March to provide real-time advice to swimmers on whether it is safe to take a dip at Durban beaches.

The new website Woz’Olwandle (Come to the sea) uses a computer model to crunch a wide range of data to estimate the likely concentrations of E. coli at several local beaches over 24 hours.

Much like a weather service report, the website will provide guidance on whether it is safe to swim, using easy-to-understand icons denoting whether water conditions are “good”, “acceptable” or “poor” (based on European Union recreation guidelines).

poo predicter website The new website currently provides data for six central Durban beaches.



The main driving force behind the project is Dr Justin Pringle, a senior lecturer and researcher who co-heads the environmental fluid mechanics research group at the University of KwaZulu-Natal (UKZN).

Pringle says his main interest as a scientist is to ensure that information gets to people and he hopes the new website will also help to stimulate new conversations about and potential solutions to the problem of sewage flows that have dented the city’s tourism image.

Read more in Daily Maverick: “Anger grows over Durban’s apparent apathy in dealing with widespread river contamination”

He notes that information about water quality is often out of date by the time it reaches beach users, either because samples are not collected daily or because of the time it takes to culture and count bacteria in a laboratory and then publish the results on beach notice boards or online. Heavy rains and strong winds can also change pollution levels overnight.

poo predicter pringle Researcher Dr Justin Pringle is co-head of the environmental fluid mechanics research group at the University of KwaZulu-Natal (Photo: Supplied)



However, the dynamic computer model that informs the Woz’Olwandle website will help to overcome some of these complications by factoring in a range of weather data and other information extracted daily from global Earth observation systems, a weather station at uShaka Beach and test results from Talbot Laboratories.

To guard against rolling blackout hitches, Pringle has taken the precaution of using a server in the US.

Bigger plans


The website launched informally on 8 March and will initially provide information on water quality at six central Durban beaches – Country Club, Pirates, North, South, uShaka and Point.

poo predicter durban A satellite image of the clear blue seas off Durban in May 2020 (right) and what the ocean looked like immediately after the April 2022 floods (left). Apart from eroded soils, sediment and other waterborne debris, nearly 66% of sewage from Durban homes was flowing untreated into rivers and the sea at least 10 weeks after the floods due to massive damage to sewage and stormwater infrastructure. (Images: Google Earth Pro)



Pringle hopes the system can be expanded to cover other beaches, such as Umhlanga, with support from the tourism and hospitality sector and research grants.

The project is part of a broader UKZN academic collaboration which may help the city to pinpoint the major sewage pollution problem areas for priority attention and repairs.

Read more in Daily Maverick: “Cape Town’s beaches may be more hazardous to health than they seem, according to sewage test results”

For example, there are plans to enlist the help of cellular biologists to study the genetic structure of bacteria to help pinpoint the source of sewage pollution at individual wastewater treatment works, stormwater outlets or rivers across the municipality.

poo predictor key The website key to interpreting the water safety symbols.



The research team will include cellular biology and genomics researcher Dr Angus Macdonald, marine geologist Professor Andy Green, ecotoxicologist Dr Dalene Vosloo and environmental fluid dynamics expert Professor Derek Stretch.

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Pringle notes that the original UKZN fluid dynamics computer model was developed by Stretch and Dave Mardon about 20 years ago and has now been repurposed to provide real-time information to the public.

The model captures a variety of data that influence the mixing and dispersion of pathogenic bacteria pollution close inshore (including rainfall and wind). It also estimates the decomposition rates of bacteria when exposed to seawater and sunlight.

poo predictor rating Though beach water was rated as ‘good’ early on 8 March at uShaka Beach, the real-time model predicts a deterioration to ‘poor’ early on 9 March.



Researchers have noted that E. coli is a common bacteria found in the gut of people and animals and is simply an indicator of the presence of faecal matter that may contain more harmful bacteria that can cause diarrhoeal diseases such as cholera, dysentery, typhoid fever or shigellosis.

According to Mardon, several epidemiological studies suggest that enterococcus is a much better indicator of pathogenic pollution in marine environments than E. coli.

The new website draws on the experience of the Beach Report Card, developed for the Greater Los Angeles area in the US. DM/OBP

https://www.youtube.com/watch?v=REeWvTRUpMk

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