Latest News Archive

Please select Category, Year, and then Month to display items
Previous Archive
12 October 2020 | Story Leonie Bolleurs | Photo Supplied
Adriaan van der Walt
Although several international studies have used temperature metrics to statistically classify their seasonal divisions, a study in which Adriaan van der Walt was involved, would be the first known publication in a South African context using temperature as classification metric.

Gone are the days when we as South Africans would experience a three-month spring season, easing into summer, and then cooling off for three months before we hit winter.

Adriaan van der Walt, Lecturer in the Department of Geography at the University of the Free State (UFS), focuses his research on biometeorology (a specialist discipline exploring the role and climate change in physical and human environments) as well as climatology and geographic information systems.

He recently published an article: ‘Statistical classification of South African seasonal divisions on the basis of daily temperature data’ in the South African Journal of Science.

In this study, which Van der Walt undertook with Jennifer Fitchett, a colleague from the University of the Witwatersrand, data on daily maximum and minimum temperatures was collected from 35 meteorological stations of the South African Weather Service, covering the period between 1980 and 2015.

They went to great lengths to ensure that they had a complete set of data before presenting it to demonstrate seasonal brackets.

First for South Africa

Their statistical seasonal brackets indicate that South Africans now experience longer summers (from October to March), autumn in April and May, winter from June to August, and spring in September.

Although considerable work has been done using rainfall to determine seasonality in Southern Africa, Van der Walt believes that these methods did not work well as there are too many inconsistencies in this approach, as identified by Roffe et al. (2019, South African Geographical Journal). To make matters more complicated – as a semi-arid region, and with desert conditions along the west coast – some regions do not have enough rainfall to use as a classifier.

Temperature, on the other hand, worked well in this study. “Temperature, by contrast, is a continuous variable, and in Southern Africa has sufficient seasonal variation to allow for successful classification,” says Van der Walt.

He continues: “Although several international studies used temperature metrics to statistically classify their seasonal divisions, this study would be the first known publication in a South African context using temperature as classification metric.”

Van der Walt says what we understand as seasons largely relates to phenology – the appearance of blossoms in spring, the colouration and fall of leaves in autumn, and the migration of birds as a few examples. “These phenological shifts are more sensitive to temperature than other climatic variables.”

Seasonal brackets

According to Van der Walt, they believe that a clearly defined and communicated method should be used in defining seasons, rather than just assigning months to seasons.

“One of the most important arguments of our work is that one needs to critically consider breaks in seasons, rather than arbitrarily placing months into seasons, and so we welcome any alternate approaches,” he says.

A number of sectors apply the temperature-based division to their benefit. “For example, in the tourism sector it is becoming increasingly important to align advertising with the season most climatically suitable for tourism,” says Van der Walt.

Temperature-based division is also used to develop adaptive strategies to monitor seasonal changes in temperature under climate change. However, Van der Walt points out that each sector will have its own way of defining seasons. “Seasonal boundaries should nevertheless be clearly communicated with the logic behind them,” he says.

News Archive

From peasant to president; from Samora Machel to Cahora Bassa
2015-03-25

Prof Barbara Isaacman and Prof Allen Isaacman
Photo: Renè-Jean van der Berg

When the plane crashed in Mbuzini, the entire country was submerged in a profound grieving.

This is how Prof Allen Isaacman, Regents Professor of History at the University of Minnesota, described the effect President Samora Machel’s death in 1986 had on Mozambique. In a public lecture, Prof Isaacman spoke about the man, Samora Machel, and the influences that shaped Machel’s life. The event, recently hosted by the UFS International Studies Group on the Bloemfontein Campus, was part of the Stanley Trapido Seminar Programme.

Samora Machel: from peasant to president
Born in 1933 into a peasant family, Machel was allowed to advance only to the third grade in school. “And yet,” Prof Isaacman said, “he became a very prominent local peasant intellectual and ultimately one of the most significant critics of Portuguese colonialism and colonial capitalism.” Machel had a great sense of human agency and firmly believed that one is not a mere victim of circumstances. “You were born into a world, but you can change it,” Prof Isaacman explained Machel’s conviction.

From herding cattle in Chokwe, to working as male nurse, Machel went on to become the leader of the Liberation Front of Mozambique (Frelimo) and ultimately the president of his country. To this day, not only does he “capture the imagination of the Mozambican people and South Africans, but is considered one the great leaders of that moment in African history,” Prof Isaacman concluded his lecture.

Displacement, and the Delusion of Development: Cahora Bassa and Its Legacies in Mozambique, 1965–2007
Later in the day, Profs Allen and Barbara Isaacman discussed their book: ‘Displacement, and the Delusion of Development: Cahora Bassa and Its Legacies in Mozambique, 1965–2007’ at the Archives for Contemporary Affairs. As authors of the book, they investigate the history and legacies of one of Africa's largest dams, Cahora Bassa, which was built in Mozambique by the Portuguese in the late 1960s and early 1970s.

The dam was constructed under conditions of war and inaugurated after independence by a government led by Frelimo. The dam has since operated continuously, although, for many years, much of its electricity was not exported or used because armed rebels had destroyed many high voltage power line pillars. Since the end of the armed conflict in 1992, power lines have been rebuilt, and Cahora Bassa has provided electricity again, primarily to South Africa, though increasingly to the national Mozambican grid as well.

We use cookies to make interactions with our websites and services easy and meaningful. To better understand how they are used, read more about the UFS cookie policy. By continuing to use this site you are giving us your consent to do this.

Accept