Cape Town’s drought under the microscope

29 January 2019 | Story Niémah Davids. Read time 7 min.
Capetonians queue up at local springs during the height of water restrictions in the city, when everything was being done to avoid the prospect of Day Zero when the taps would ultimately run dry. <b>Photo</b>&nbsp;<a href="" target="_blank">Widad Sirkhotte, Flickr</a>.
Capetonians queue up at local springs during the height of water restrictions in the city, when everything was being done to avoid the prospect of Day Zero when the taps would ultimately run dry. Photo Widad Sirkhotte, Flickr.

Research by oceanography student Precious Mahlalela into the cause of Cape Town’s recent devastating drought has earned her the acknowledgment of having a paper published in top international scientific journal Climate Dynamics.

Publication of coursework MSc research in renowned scientific journals is a great achievement, particularly when it addresses such a topical and complex subject, said Professor Chris Reason of the Oceanography Department in the University of Cape Town’s (UCT) Faculty of Science.

“We are happy. It’s always gratifying when a student gets a paper published, especially in a leading international journal. One hopes that when they graduate, they will continue making a strong and meaningful contribution to South African research,” he added.

For Mahlalela, a current PhD student, the dearth of published literature on the Western Cape’s rainfall variability was the main reason she dedicated her coursework master’s research project to the topic last year. The fact that the subject directly affects all Capetonians, as well as people beyond the province’s borders, was a bonus.

The Mother City has been gripped by the worst drought in 100 years. While dam levels have improved, and water restrictions were reduced from level 5 to level 3 at the end of 2018, water rationing remains in place. This year Cape Town authorities will focus their efforts on recovery plans and the implementation of initiatives to help the water-scarce city bounce back after it narrowly averted the threat of Day Zero.

“At the height of the drought and panic to avoid Day Zero, the topic concerned all of us. In fact, it still does.

“There are no restrictions and limitations when it comes to who needs water, it affects everyone. Everyone also wants to understand why we find ourselves in this situation,” Mahlalela explained.


“There are no restrictions and limitations when it comes to who needs water, it affects everyone.”

The study

Investigating the Western Cape’s rainfall patterns and linking them to the city’s water shortage was step one, and Mahlalela’s primary focus area.

She analysed station rainfall data obtained from the South African Weather Service for the period 1979 to 2017, surveying four Western Cape regions (the greater Cape Town area, the northern West Coast, the Overberg and the Garden Route) to establish different characteristics in the seasonality of the recent drought when compared to previous droughts.

In particular, and when compared to the full winter rainy season (April to September), Mahlalela’s research found that the early winter drought (April to May) was severe across all regions during the 2015–2017 period.

“Drier winters result from weaker approaching cold fronts, cold fronts steered further south than average, a reduced number of fronts, or all of these factors. A large-scale climate pattern – the Southern Annular Mode (SAM) – when anomalously positive, can cause such changes in cold fronts,” she said.

Mayosi remembered
Figure 5 shows the climatological April-May low level moisture flux (top panel), the anomalies during dry winters (middle panel) and wet winters (bottom panel). Photo Supplied.

“It also leads to higher than average pressure over the mid-latitude South Atlantic and a weakening of the westerly wind belt that circles the Southern Ocean.”

Not enough rain

Mahlalela’s research revealed that, in recent decades, the early winter season recorded dry conditions. She explained that this season was associated with a weaker subtropical jet (a belt of strong upper-level westerly winds) during 2015–2017, and less moisture being transported towards the South Western Cape from the South Atlantic.

This, Mahlalela said, was one of the reasons the region received reduced rainfall during recent winters.


“There appears to be a climate change type of signal emerging and we need to increase our planning and become resilient.
We don’t have time to think, we need to act.”

“What happened during 2015–2017 is that both the South Atlantic Anticyclone (a high-pressure system in the subtropical South Atlantic Ocean) and the jet stream were shifted anomalously far south.

“These shifts, together with a tendency of more berg winds over the West Coast, steered the cold fronts further south than average. It resulted in far less moisture to produce rainfall over the South Western Cape, which led to a severe drought.”

Mahlalela’s research also pointed to grave concern about the likelihood of good autumn or early winter rains in the future.

She explained that her investigations of output from climate models used in the Fifth Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC) show that prolonged and severe dry periods, as experienced in Cape Town between 2015 and 2017, can be expected in future.

“Although the CMIP5 [Coupled Model Intercomparison Project Phase 5] climate models have difficulty in representing the onset of the winter rains in April in the current climate, there seems to be a clear signal of reduced winter rainfall in future, particularly in May and June.”

The way forward

Plan, plan, plan, then act – thatʼs the way forward, she said.

There’s not much time left, and Mahlalela stressed that action to conserve water needs to start now, especially as the population continues to increase and the demand for water grows.

“It all comes down to proper and effective planning and management, together with responsible water usage.”

Water storage and distribution should become a key focus, and not only for the Western Cape. Other Mediterranean climate-type regions such as California, Chile and southern Australia have experienced similar rainfall and water shortage challenges, along with many of South Africa’s summer rainfall regions.

But it’s a unified effort that requires massive collective buy-in, Mahlalela said.

“There appears to be a climate change type of signal emerging and we need to increase our planning to become resilient. We don’t have time to think, we need to act now.”

Mahlalela is already working towards her next research paper, as part of her PhD, which focuses on the ongoing drought in the Eastern Cape.

  • Mahlalela, P.T., R.C. Blamey and C.J.C. Reason 2018 Mechanisms behind early winter rainfall variability in the southwestern Cape, South Africa, Climate Dynamics,

Creative Commons License This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.

Please view the republishing articles page for more information.

Highlights from 2019


As we look back on 2019, we celebrate the top 40 stories that were most popular with readers of the UCT News website during the year.

Prestigious scholarship for star pupil Prospective UCT student Terrell Demorgan has been awarded the inaugural Daniel Samuel Maseko Memorial Scholarship for 2020. 31 Dec 2019 Highlight from 2019
UCT adds Khoekhoegowab to its language courses UCT announced during its Africa Month celebrations the addition of Khoekhoegowab, the indigenous Khoisan language, to its multilingual short courses. 30 Dec 2019 Highlight from 2019
UCT in top 1.3% globally UCT ranks best in Africa, according to the latest Center for World University Rankings. 30 Dec 2019 Highlight from 2019
Touch down for SA’s banking Siri Four UCT students have developed a one-stop banking shop that performs banking transactions, monitors account activity and speaks four South African languages. 30 Dec 2019 Highlight from 2019
Warm response to Moloi-Motsepe’s election as chancellor Dr Precious Moloi-Motsepe has been elected as the University of Cape Town’s sixth chancellor. She will take up the position from 1 January 2020. 29 Dec 2019 Highlight from 2019
UCT tops in Africa in all five major rankings UCT took the top spot in South Africa and jumped back into the 201–300 band in the latest ShanghaiRankingʼs Academic Ranking of World Universities 2019. 28 Dec 2019 Highlight from 2019
UCT best in Africa in world rankings UCT has been ranked the best university on the continent in the 2020 US News Best Global Universities rankings. 27 Dec 2019 Highlight from 2019
Cape Town’s drought under the microscope PhD candidate Precious Mahlalela dedicated her masterʼs thesis to understanding the cause of the Mother City’s recent drought and received recognition in a top international journal. 27 Dec 2019 Highlight from 2019
SA’s first ‘LinkedIn for creatives’ Three UCT Commerce students have designed an online platform that gives creative professionals a way to network and share their work with a vast audience. 27 Dec 2019 Highlight from 2019
Common contraceptive could raise TB risk A breakthrough study at UCT has revealed that one of the country’s most commonly used injectable contraceptives could potentially increase users’ risk of contracting tuberculosis. 26 Dec 2019 Highlight from 2019
UCT graduates ‘highly sought after’ UCT Careers Service’s Graduate Exit Survey confirms that the university’s graduates remain “highly sought after”, with only about 10% of the 2018 class still seeking jobs. 25 Dec 2019 Highlight from 2019
Levelling the maths, physics playing field Thabang Sebetoane’s brainchild, the tutoring project Tshehetso, uses coaching and mentoring to prepare potential engineering students for success at university. 24 Dec 2019 Highlight from 2019
Dual degree was ‘a juggling act’ With diligence and perseverance, UCT student Kira Düsterwald simultaneously graduated with her degree in medicine and her masterʼs in neuroscience. 24 Dec 2019 Highlight from 2019
Balance key to two-in-one degree Balance was key to UCT’s Nicola Steinhaus graduating with both a bachelor’s and master’s degree concurrently. 24 Dec 2019 Highlight from 2019
UCT master’s degrees pull international students A significant number of UCT’s 605 new international students in 2019 have signed up for master’s degree programmes, a trend that’s evident across all six academic faculties. 23 Dec 2019 Highlight from 2019
‘This is my mother’s graduation’ While it’s his name on the degree, Ntebogang Segone says his 17 April graduation belongs to his mother. 23 Dec 2019 Highlight from 2019
New ‘fully funded’ scholarship for top young researchers UCT's new Vice-Chancellor Research Scholarship will support and develop the university's top young researchers as they tackle society's most pressing challenges. 23 Dec 2019 Highlight from 2019
Hon doc for maths ‘trailblazer’ Phakeng VC Prof Mamokgethi Phakeng says her honorary doctorate from the University of Bristol is “a recognition of the many people who made me, those I represent”. 22 Dec 2019 Highlight from 2019
Student’s urine-recovery system for R600m building In a first for South Africa, a urine-recovery urinal system developed at UCT has been incorporated into the design of a R600-million Centurion office building. 21 Dec 2019 Highlight from 2019
Tackling the fake qualifications threat Universities and employers in South Africa have a vital tool to tackle the fake qualifications menace, thanks to the country’s world-first online verification system MiE. 20 Dec 2019 Highlight from 2019
Changing face of UCT infrastructure A new 500-bed residence, an education building and a redeveloped North Bus Stop are among seven new developments in the pipeline to meet UCT’s needs to 2035. 20 Dec 2019 Highlight from 2019
Student’s 3D-printer plan to change education UCT student Denislav Marinov has big plans for democratising quality education in South Africa, one 3D printer at a time. 20 Dec 2019 Highlight from 2019
Black women academics: ‘Stay in the system’ Vice-Chancellor Professor Mamokgethi Phakeng’s plea to young black women academics ahead of Women’s Day is that they “stay in the system” to change the status quo in academia. 19 Dec 2019 Highlight from 2019
UCT back in top 10 for development studies UCT has moved up two places in the 2019 QS World University Rankings by Subject, to reclaim its position in the top 10. 19 Dec 2019 Highlight from 2019
‘Something is deeply wrong with our society’ During a memorial service for Uyinene Mrwetyana, UCT chancellor, Mrs Graça Machel, said South Africa faces a deeply rooted problem and needs help. 19 Dec 2019 Highlight from 2019
Students share their top study tips With just over a week to go before exams start, UCT students share their tried and tested tips for study success. 18 Dec 2019 Highlight from 2019
Leverage privilege to change education, Madonsela urges Apartheid has cast a huge shadow over the country, particularly education, and it will need all of society to break the cycle of poverty. 18 Dec 2019 Highlight from 2019
UCT says ‘Enough is enough’ at Parliament picket UCT students and staff were joined by members of the public in a picket at Parliament to protest escalating sexual and gender-based violence. 18 Dec 2019 Highlight from 2019
Matric maths pass rate poses significant challenge for universities Universities may have to swop targeted interventions for systemic change if they are to successfully graduate the strongest students currently exiting the South African school system. 17 Dec 2019 Highlight from 2019
Solving SA’s literacy crisis An education expert told UCT Summer School participants that thereʼs no quick fix for South Africaʼs literacy crisis. It will take time and hard work. 17 Dec 2019 Highlight from 2019
Racism and ‘xenophobia’: 10 key points UCT News highlighted 10 key points from UCT PhD candidate Ivan Katsere’s op-ed on the centrality of racism in violence against African migrants. 17 Dec 2019 Highlight from 2019