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‘Where on earth?’ The CGA knows the answer
Author: Corporate Communications and Marketing (Hannelie Booyens)
Published: 12/07/2024

​Having a bird's eye view of the world and using that perspective to advance a multitude of scientific fields and commercial industries lies at the heart of Garth Stephenson's work as general manager of the Centre for Geographical Analysis (CGA) at Stellenbosch University (SU).

Nestled within the Department of Geography and Environmental Studies, the CGA is a beacon of innovation in the field of geospatial analysis.

The CGA specialises in geographical information systems (GIS) and earth observation (EO), providing services across various sectors. Some of its innovative projects include agricultural modelling, climate data analysis and water use quantification.

Whenever Stephenson is asked what exactly the CGA does, he has a very simple answer. “If you want to know where something is happening, we do research to find the answer," he explains.

“I'm genuinely fascinated by where things happen. When somebody says to me 'I was here and there the other day, and this happened,' I immediately want to get on my phone and see where it is. I'm so used to looking at the world from above. I find spatial patterns fascinating."

Tinkering with maps

Under Stephenson's leadership, the CGA has been pushing the boundaries of how geographical data can be harnessed to address real-world problems.

Stephenson's journey into the world of geographical information systems began with his passion for the environment. “Although I've always loved tinkering around with maps, I didn't do geography as a subject in high school, which is quite ironic as it's now such a central part of my job. Back then I was more interested in computer science. I went to the University of Cape Town to do a BSc in geographical science, ecology and zoology."

After graduating in 2003, he worked a short stint as an intern for an environmental consulting company, finding geographical information systems the most interesting and rewarding part of the job. Realising the potential of this technology led him to pursue further studies at SU, where he completed his BSc Honours in geographical information systems and environmental analysis in 2006, followed by a master's degree in environmental management and geographical information systems in 2010.

Joining the CGA right after he completed his MSc, Stephenson's expertise and dedication saw him rise to the position of General Manager in 2014. His role involves strategic planning, project management and the development of new GIS and EO products, along with a strong emphasis on research and training.

The CGA's work is rooted in sophisticated computer modelling to meticulously analyse data, often with the aid of machine learning to provide insights that are invaluable to a diverse clientele.

“We use satellite imagery, aerial photography, drone footage and sometimes in-field instruments to record the data," Stephenson explains. “We deal with terabytes of data that we process daily. We have quite a large cluster of hardware that we use for our processing that's running almost continuously to create these large spatial datasets."

Bridging agriculture and technology

Beyond work for external clients, the CGA has done geospatial work for many SU faculties and departments ranging from Forest and Wood Science, Agronomy, Horticultural Science, Soil Science, Plant Pathology, Viticulture and Oenology, Conservation Ecology and Entomology, Botany and Zoology, Psychology, Economics, Logistics, as well as with various researchers at the Faculties of Engineering and Medicine.

One of the CGA's standout contributions is in agricultural modelling. Working closely with organisations such as HortGro and SA Wine, the Centre employs satellite imagery and other geospatial tools to monitor crop health and predict yields with remarkable accuracy. This collaboration has led to the development of tools that help farmers make data-driven decisions, enhancing productivity and sustainability.

Recognising the critical impact of climate change on agriculture, the CGA has also played a pioneering role in climate data analysis. In partnership with Innovus, the Centre developed TerraClim, a spin-off company led by Dr Tara Southey that commercialises the Centre's climate data analysis tools. TerraClim's inception involved aggregating weather station data across the Western Cape into a centralised, standardised database facilitating comprehensive climate analysis.

“With TerraClim, we develop layers of climate data from around 600 weather stations across South Africa that we pull into a central database on our servers on a daily basis. We standardise, clean and gap-fill this weather data, and use it to interpolate wall-to-wall climate surfaces. The products developed through this allow stakeholders in agriculture to make informed decisions based on accurate climate data," Stephenson explains. This tool is particularly useful for farmers who need to understand climate trends and their impact on crops, helping them mitigate the adverse effects of climate change.

Water use quantification

Another significant area of the CGA's expertise is water use quantification. In collaboration with the Water Research Commission, the Centre mapped irrigation fields in South Africa. “We used satellite imagery to map areas of irrigation across South Africa and remotely sensed evapotranspiration data to quantify how much water is being used by irrigation within an area. Similar approaches have been used to determine how much water is used in commercial and indigenous forests." These initiatives help in understanding water usage by different land uses and plays a crucial role in optimising water allocation – a critical issue in a water-scarce country like South Africa.

The scope of the CGA's work extends far beyond agriculture and climate data. The CGA has assisted the Council for Scientific and Industrial Research with modelling of coastal erosion and flood risks, and its expertise is sought after in fields as varied as commercial forestry, conservation ecology, urban planning and even crime mapping. One of its recent projects involved assisting SU researchers with pollution exposure analysis related to pregnancy, showcasing the Centre's ability to apply geospatial analysis to health studies.

Another service offered by the CGA involves map production. The Centre provides diverse cartographic services for academic and non-academic publications by developing maps tailored to clients' needs.

Committed to advancing geospatial training, the CGA offers part-time, online courses in geographical information systems and earth observation accredited by SU. These courses are tailored for industry professionals and students, providing them with the skills needed to leverage geospatial technology in their respective fields.

“Our short courses are incredibly popular, with participants ranging from government officials, NGOs, private companies and academic researchers and even individuals outside of the geospatial field who are simply interested in making maps," says Garth. The next short course will be presented from 29 July to 23 August.

PHOTO: Stefan Els