In the midst of the country’s challenges in ensuring water quality for all, a team of researchers at the CSIR has applied their expertise to improve their understanding of microalgae biodiversity and its pivotal role in supporting the ecosystem health of South Africa’s drinking water dams.

On Tuesday, 17 October 2023, a scientific experiment unfolded at one of the largest dams in the country, the Theewaterskloof Dam in the Western Cape. Dr Lisl Lain, Dr Marie Smith, Hein Swart and Alistair Adonis from the CSIR were joined by Francois le Roux and Emile Lewis from the Theewater Sports Club. Together, they ensured that all systems were in place to deploy Gizmo, Africa’s only hyperspectral radiometric buoy.

This activity is a crucial component of a research project aimed at advancing scientific knowledge and decision-making processes to ensure high-quality water for South Africans. The research focuses on enhancing the utilisation of freely available satellite data for improved monitoring and understanding of the country’s freshwater ecosystems. The Theewaterskloof Dam serves as an ideal site for developing these capabilities. Dr Lain, a senior researcher at the CSIR, describes the Theewaterskloof Dam as “dynamic”, with a reputation for displaying a wide range of algal types. “Understanding the variety of life that supports aquatic ecosystems in our drinking water dams is paramount, and microalgae, being the smallest living organisms, play a critical role in nutrient cycling,” she elaborates.

The Theewaterskloof Dam was selected as the study site due to its expansive size, making it easily discernible in satellite images. While the buoy continuously measures the in-water light field (water colour), routine water sampling is conducted for laboratory analysis to identify the types and concentrations of algae, sediment and dissolved substances. These measurements are then correlated with water colour, as exceptionally sensitively measured by the buoy. Satellites also capture water colour, but from a birds-eye view. Therefore, understanding the relationship between data from all of these platforms is crucial for confidently utilising satellite data.

Due to heavy rains in the area during September this year, the usually clear freshwater Theewaterskloof Dam was tainted with a muddy brown complexion on the day of the research. This led to a few technical difficulties, which the research team successfully resolved Within minutes of Gizmo being positioned on the water surface, sampled data started trickling in – much to the excitement of CSIR senior research engineer, Hein Swart. 

Gizmo, having been deployed before, with Swart playing a leading role in its first assembly and subsequent innovations, was equipped with a series of instruments for this research. The team makes use of a combination of satellite data and in-water physical and chemical measurements to assess microalgal diversity in near-real time. This approach allows for the early detection of potential overgrowth of toxic algal species, which could negatively impact water quality and ecosystem stability. “The data accumulated will be used and applied to many other dams all over South Africa,” Lain says. 

“Every deployment of the buoy improves our understanding and generates more information. The data is currently under analysis by several stakeholders. Consequently, the research process in this project not only aligns with significant national water quality objectives, but also contributes to the global understanding of algal biodiversity, growth and their interaction with light and nutrients,” Lain says.

This project serves as a prime example of excellent internal, multidisciplinary collaboration, drawing invaluable contributions from various CSIR entities including the Coastal Systems and Earth Observation Research Group, Coastal Systems Environmental Analytical Laboratory the Centre for Robotics and Future Production. External support from Theewater Sports Club has also played a crucial role in the project’s success.  

South Africa’s monitoring programmes, water quality assessment and sampling management constitute collaborative efforts that operate at the intersection of science, policy and management. This integrated approach is essential for effectively managing dams and ensuring the sustainability supply of healthy drinking water. The success of these initiatives hinges on the active participation of various institutions and organisations.

This deployment will allow Gizmo to call the Theewaterskloof Dam its home until the end of December 2023.