Chapman's Peak is closed after a landslide caused by the storm blocked the road. Picture: Armand Hough / African News Agency (ANA)
The repairs caused by the storm that battered the Cape regions, specifically Western and Eastern Cape will cost billions and South Africa will need ongoing investment in infrastructure.
This is according to Stellenbosch University Professor Richard Walls of the university’s Department of Civil Engineering, who gave in-depth insight about the storm damage and its costs.
Walls noted that at this point it is “very difficult to estimate costs” but said the costs may go into billions.
“Damage will be in the billions for damage to roads, stormwater, electrical lines, formal and informal homes, mudslides, losses by farmers, efforts by municipalities to clear up after the event, etc,” he said.
The storm left a trail of destruction in its wake. Properties were damaged and people were forced to evacuate, trees have fallen, power outages occurred and road closures were implemented.
But how long will these repairs take and what can be done about it? Short answer is it varies, but the long is much more interesting.
“Damage across the Western Cape varies quite extensively to light damage that can be quickly remedied to extensive damage that may require months for full repairs,” Walls told IOL.
He added that weather and hydrological data will show what sort of floor event this was, e.g. 1 in 5 year or 1 in 100 year and this may vary regionally.
Walls noted that in extreme events, damage to infrastructure does occur adding that it is “typically seen that areas with better infrastructure, which has also been well-maintained, experience less impact”.
Walls also stated that as cities expand, there is more runoff leading to higher flood peaks and when roads and bridges have been undercut by rivers, they are potentially dangerous areas which people should avoid.
On that note, Walls urged people to follow guidance from the local municipalities where roads have been closed and not try to find their own way to their destinations.
“Such events (the severe weather) highlight how we need ongoing investment in infrastructure across the country. The cost is likely to be in the billions which will obviously have a negative impact on the country. Such events also highlight how early warning and communication are key in such events.”
What about the damage done to roads and the road closures that happened as a result?
When there is inclement weather, numerous reports emerge over rockfalls and mudslides. Roads such as Chapman’s Peak Drive usually face road closures in this event.
Walls noted that mountain passes where these events have occurred require local engineers to investigate and ensure they are safe.
With regards to the storm, road damage varies from small mudslides that can be cleared in hours to large-scale damage from rivers which have affected bridges.
“Where damage to roads and foundations have occurred, the time to repair them may vary from weeks to months. Furthermore, local municipalities will need to ensure that slopes, abutments and embankments have not been significantly damaged such that in the next flood event failure could occur.”
As we looked at roads and general storm damage, it is important that we focus on bridges as it remains an integral component of our infrastructure, and their structural integrity is paramount.
Walls said bridges are designed for flood conditions and their foundations, piers and structural members can and should withstand severe conditions. But this isn’t always the case.
“As cities densify, land usage changes, and infrastructure is not maintained it is possible that flows could increase beyond that which a bridge was designed for. This could lead to extensive damage.”
As with infrastructure and roads, the repair methods used for bridges will vary depending on the type of bridge and extent of damage: A steel bridge may require strengthening where members have been damaged; a small farm bridge may need to rebuilt if partially washed away; and a large concrete bridge on a national road may require repair to the road surface or to sections that have been damaged.
Walls reiterated that there will be extensive localised damage to roads and stormwater that municipalities will be repairing for months.
In light of this, how can the resilience of infrastructure be improved? Walls said we would need accurate data regarding rainfall and floods from which peak flows can be more reliably predicted. It is only then we can size bridges and culverts to ensure that they can withstand such flood events.
IOL