Flash floods have been plaguing the planet in 2016. In June, flash floods forced the government of France to close the Louvre in Paris and 25,000 people were left without power. 500 miles away, Germany also experienced flash flooding that caused 5 deaths and left several people missing. Lest we forget the 2015/16 floods of Ireland and Great Britain. Storm weather also battered South Australia at the end of September, this year. Engineering industries were shut down due to the weather. Power stations went down and 80,000 people were without power in Adelaide. The storm was thought to be a "one-in-fifty-year" weather event.

EIT Stock ImageThe fact that weather is delaying the work of engineering industries and leading to loss of life - in some countries - is not an understatement.

Now, South Africa has received a fresh bout of flash flooding due to stronger storms that are exacting cloudbursts over Johannesburg. The explanation behind why the sudden flooding events are happening relates to the weather cycle of El Niño's departure, and the onset of La Niña . Some are also pointing the finger at climate change to try and explain why the storms are so severe. South Africa has gone from unprecedented drought, and now is facing the same problem India is: replenishing water - but too much of it.

On Wednesday afternoon, severe storms caused flash floods in the South of Johannesburg. The South African Weather Service has said that extreme weather conditions will continue up until Friday. The N3 highway in Johannesburg saw flooding in both directions. Cars were swept away due to the high volume of water due to the rainwaters.  A Twitter user @mandlamZA, wrote: "So clearly, our roads and highways were not built for the rain."

Flooding also cut off access to the country's main airport and forced airplanes to circle the airport before they could make a landing. As a result, flights were also delayed.

The City of Tshwane's Facebook account wrote: " Of late, four people died after a cloud burst at Midrand and OR Tambo, flooding the freeway at the Linksfield off-ramp. Massive water accumulated at low-lying areas of the freeway and many cars were caught up unexpectedly and covered with water up to their roofs."

EIT Stock ImageMunicipal governments and civil engineers are now debating how to avoid deaths in flash flooding events. Low-lying areas are unfortunately in the crosshair of a storm and are more prone to flooding  than built up areas at the top of hills. Citizens in shanty towns built along the Jukskei River were displaced due to the rising floodwaters there. The area was the worst hit, 200 families lost their homes.

A disaster management center has started investigations into the drainage systems and general destruction of the floods.

Johannesburg Roads Agency director Sean Phillips said: "When you get very unusual rainfall like we had last night then it overloads the drainage system. It would be possible to design the drains to be able to cope with these extreme rains, which occur occasionally." The water exceeded the stormwater systems' capability.

The question that remains, globally, is, should governments be looking at storm drain redesigns in preparation for climate-change-level volumes of rainwater?

The Department of Civil Engineering at McMaster University in Canada has researched the topic in their study entitled Climate Change Impact on Design Storm and Performance of Urban Storm-Water Management System. They write:

A number of future climate projections indicate a likelihood of increased magnitude and frequency of hydrological extremes for many regions around the world. The urban storm-water management infrastructures are designed to mitigate the effect of extreme hydrological events. Changes in extreme rainfall events will have a significant implication on the design of strom-water management infrastructures.

The study they conducted found that even Canada's infrastructure would suffer under "future climate condition."

Over-capacity drainage systems can also lead to sewage making its way into the waterways. Including the aforementioned: transport systems and residential flood damage are the main areas of focus for drainage systems that are being pushed past their capacity with the increase in water volume that the world is experiencing.

 

 

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