A study used advanced deep learning methods based on nighttime light (NTL) data to assess radiance patterns across major South African cities, presenting an innovative method to monitor urban development issues.
And along the way, the researcher, Dr Zandile Mncube, fulfilled a long-held aspiration. Having completed her Bachelor of Science, Bachelor of Science Honours and Master of Science degrees at the University of the Free State, Mncube has now graduated with a PhD in Geography from the University of KwaZulu-Natal (UKZN), within the discipline of Geographical and Environmental Sciences.
Mncube described UKZN as her “dream institution since high school,” explaining that although she had initially hoped to study Medicine, her path ultimately led her to Geography. “When I completed my master’s degree and needed to change supervisors, the opportunity to apply to UKZN presented itself again, and I embraced it wholeheartedly.” UKZN’s strong academic reputation, diverse research community and career-support networks made it the ideal environment to pursue her doctoral studies.
Her PhD thesis: ‘A Geo-Temporal Analysis and Forecasting of Nighttime Light Intensities over Three Largest Municipalities of South Africa’, broke new ground in the use of satellite-derived data.
Mncube’s research results indicate that NTL intensity in Durban, Cape Town and Johannesburg is consistent with urban expansion, loadshedding and economic patterns. Thus, NTL serves as a valuable indicator of urban patterns, providing an important and unique planning tool for data-scarce regions.
Mncube elaborated: “I used nighttime light data captured by satellites; essentially, the lights we see at night from households, streetlights, traffic signals, commercial centres and billboards. These lights create a visible ‘footprint’ of human activity on Earth. I examined how these lights change over time and how they relate to urban growth, environmental conditions and economic activity.”
A central aim of her work was to evaluate whether NTL data could serve as a reliable alternative to traditional statistical data such as census results, which in South Africa are collected only every 10 years. “NTL data is available monthly, making it more accessible for timely decision-making in planning, resource allocation and sustainable development,” she explained.
Her research integrated geography, GIS, remote sensing and data science, including deep-learning techniques, highlighting its interdisciplinary nature.
Mncube’s interest in this field developed from her master’s research and a desire to push beyond conventional approaches and to think innovatively. Recognising that remote sensing of nighttime lights remains under-researched in South Africa and across much of the continent, she was motivated to contribute foundational knowledge: “I saw potential for this dataset to become a ‘gold mine’ for studying development, environmental change and economic patterns on the continent.”
She emphasised the broader significance of her research, noting its potential to transform how urban and environmental changes are monitored. “By using monthly NTL data, we can observe dynamic shifts in human activity with far more precision than what traditional, infrequent census data offers,” she said. Her work also creates opportunities for African researchers to engage more deeply with a field largely dominated by developed countries, fostering locally relevant innovation and solutions.
Looking ahead, Mncube plans to strengthen her academic profile through publishing in reputable peer-reviewed journals. “I hope to collaborate with other young scientists, share my experiences and contribute to capacity building in my field,” she said. She also expressed interest in pursuing a postdoctoral fellowship and exploring international collaborations to expand her research networks.
She credited her supervisor Professor Sifiso Xulu as a key influence in her journey. “He has guided me through challenges, encouraged resilience and emphasised the importance of integrity, ethical conduct and uplifting others,” she said, describing him as a “destiny helper” who shaped both her academic and personal growth.
Outside of academia, Mncube enjoys reading fiction to understand human behaviour and relationships better, as well as jogging and taking afternoon walks to maintain balance and wellbeing.
She offered the following encouragement to others: “Postgraduate studies are not just about earning a degree; they play a vital role in addressing real-world challenges.”
As a young woman in science who completed her PhD before the age of 30, and as someone from a village where many people have never even heard of a PhD, Mncube hopes her story will inspire others to pursue advanced education. “With dedication, guidance and resilience, education can open doors beyond what you imagine – including international opportunities and personal growth.”
Words: Sally Frost
Photograph: Sethu Dlamini