/ 23 February 2024

Cape Town transport infrastructure at high risk of flooding, fires

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Firefighters battle a blaze on Signal Hill in Cape Town. Wildfires are likely to become frequent. Photo: Rodger Bosch/Getty Images

The City of Cape Town’s transport infrastructure, valued at R20 billion, is at high risk of coastal flooding and fires, according to a new analysis.

In a paper published in the Journal of the South African Institution of Civil Engineering, a team of University of Cape Town, the researchers quantified the volume of transport infrastructure at risk of severe weather events, estimating the direct economic value.

“Damage to transport infrastructure, in turn, threatens access to socio-economic opportunities,” the paper stated.

Transportation is directly and indirectly vulnerable to weather and climate change, explained Tanya Lane-Visser of the UCT Centre of Transport Studies in the department of civil engineering, who worked  with Marianne Vanderschuren, a leading transport expert. 

“Direct vulnerabilities consist of impacts on physical infrastructure and non-physical impacts on human health, behaviour and decision-making,” Lane-Visser said.

The indirect vulnerabilities are caused by the interaction with and dependence of the transport sector on other critical infrastructure and social systems, including water, electricity, information and communication and petroleum systems.

Quantifying the potential socio-economic effects of climate-related hazards in the city revealed that 79.6% of Capetonians live in high-risk areas, she said. “Some 45.5% of the population live in areas at high risk of flooding and a further 11% will be exposed to extreme cases of flooding.” 

Coastal flooding could affect as much as 28.9% of the population. “Employment levels are highly correlated to that of the population and adverse weather can potentially negatively impact as much as 50% to 80% of the city’s labour force.”

The analysis showed that 15.2% of the city’s schools and 28.8% of healthcare facilities are in high-exposure areas. “Extreme weather events can, thus, have a substantial impact on access to healthcare and, to a lesser extent, education opportunities in Cape Town,” Lane-Visser said.

Climate forecast

Geographical information systems (GIS) were used to overlay areas exposed to climate-related threats on the city’s transport network and infrastructure, enabling the identification and quantification of the volume of infrastructure at risk. 

Four key climate related changes confront the city. These are decreased annual average rainfall and a change in the seasonality of rainfall; increased mean annual temperatures with higher maximum temperatures (more hot days and more frequent and intense heatwaves); increased average wind strength; increased intensity and frequency of storms, leading to short, high-intensity rainfall events; and increased size and duration of coastal storms. In addition, sea level rise will continue to occur.

The research described how the frequency of low-rainfall years in the city has already doubled and “the eye-opening ‘Day Zero drought‘ in Cape Town from 2015 to 2017 is still fresh in most Capetonians’ memory”.

“Expected increases in temperature, combined with the effects of increased wind speeds and low humidity, result in the increased fire hazard risk — both for natural (veld) fires and urban fires. 

“Greater wind strength and prolonged winds exacerbate challenges for fighting and containing fires that have started, ultimately influencing the potential damage fires can cause,” the paper said, noting how in October 2018, 4 000 people were displaced by a fire in Khayelitsha and 500 informal dwellings were destroyed in Capricorn Park a week later.

Operations at the Port of Cape Town “are adversely affected by the occurrence of strong winds, as evidenced by port closures of 9.5 days in December 2019 and four consecutive days in January 2020”, while Cape Town recorded its highest-ever temperature (45.2°C) in January 2022. 

“This exceeds the previous maximum by 3°C. Cape Town was the hottest place in Africa on that day.”

The authors cited another study that found that 334 major flood events occurred in the Western Cape from 1900 to 2018. Flooding in June 2008 left 5 500 people homeless on the Cape Flats, only to be followed by floods in July 2008 that affected 16 000 people. 

“The most recent major flood in Cape Town occurred in September 2023, where widespread flooding, landslides and rockfalls forced the closure of all major roads leading into Cape Town. 

“The storm, intensified by climate change, claimed at least 11 lives and forced the evacuation of around 1 000 low-lying homes. Although Cape Town is predicted to become drier, the seemingly contradictory occurrence of extreme rainfall events is expected to increase, due to changing weather patterns in the region.”

High exposure

Lane-Visser said about 24% of all roads in the city fall in the high exposure areas and are deemed at risk of damage or destruction from adverse climate events. 

“Even more concerning is that more than half (52.6%) of all moderately-sized taxi ranks in the city are in these high-risk zones. Additionally, 13.6% of MyCiti stops and stations and 23% of GABS [Golden Arrow Bus Services] bus stops are highly exposed, while a third of all rail stations and 23% of railway tracks are located in high-risk areas.” Plus, 6% of national roads in the city’s limits run through high-risk areas.

In addition to the analysis, Lane-Visser said three specific climate-related hazards (coastal flooding, flooding of low-lying areas and fire vulnerability) were modelled individually to highlight their relative risk contributions and the geographical differences between their effects.

“Almost 27% of minibus taxi routes and 35% of their daily stops lie in high-risk areas. Adverse weather can, thus, cause massive disruption to almost a third of taxi routes in the city. The MyCiti network uses large portions of the coastline on the Atlantis corridor, yielding around 15% of the network at risk of coastal flooding. The biggest threat to GABS is the threats affecting the suburbs that the buses pass through.”

The researchers said their analysis can inform planners and decision-makers on how to improve the resilience and where to reduce the vulnerability of transport infrastructure in the city.

Vanderschuren said proofing and maintaining infrastructure, adding new infrastructure and developing appropriate response strategies are all prudent governance tasks that can minimise the risk that severe climate events pose to transportation systems. 

Investing in fire safety protocols and disaster response plans will benefit the city, while raised infrastructure would “substantially decrease the threat that flooding of low-lying areas poses to transport mobility”.