Flood engineer explains why we get it wrong every time
Expert says factors such as climate change and slow responses continue to harm us
What do we do wrong about floods? A professor at Western University who specializes in natural disasters is at a loss where to start. First, there’s inadequate floodplain mapping. Then there’s a government that sends in the army after the flooding happens.
Don’t forget rebuilding homes after a flood destroys them, daring the water to rise again.
Slobodan Simonovic, director of engineering studies with Western’s Institute for Catastrophic Loss Reduction, says we fail to learn from our mistakes and from the devastating power of nature.
Speaking to the Citizen, he laid out some of the ways we let floods clobber us time and again:
OUTDATED MAPS
We treat maps as final documents, but nature evolves and the so-called 100-year-flood may in fact happen more often, Simonovic said.
“Hydrologic conditions are changing. Precipitation is changing. Flow is changing. These lines (on flood maps) are not fixed … If you establish them today, they’re established usually using the historical data on precipitation and flow.” But with rainfall and land use changes, the flood risk also changes over time.
The logical response is to rewrite the flood maps, he said, yet this rarely happens. It’s hard to know what happens once every 100 years when we don’t have 100 years of data.
Ottawa has official weather records since 1939, and historic records of flooding are unreliable because our modern pavement, sewers and dams have changed the way water flows.
THE HUMAN FACTOR
There’s also psychology.
It’s human nature to say, “We’ve had our big flood, so we won’t have another for 100 years.” In fact, we could have another in 10 or 20 years. Only over the centuries will it all even out, assuming the models are all accurate in the first place.
SLOW RESPONSES
We respond too slowly.
Why wait until homes are already surrounded by water to send in the army, he wondered.
“We cannot stop floods from occurring, obviously. The coordination between various levels of government is relatively weak” in flood work and other disasters, he said.
The problem is local governments are the first wave of defence in Canada’s system, first in planning, then in piling sandbags when the water rises.
“When the disaster exceeds the capacity of the locals to deal with that, then we move to the provincial level,” and later to federal assistance.
There are delays while local governments wait for the funding or other involvement from senior governments, “and then everything gets moving, but the water is moving also. And in some cases it’s much faster than the decisions. I think that creates some impact on people — on economic damage, as well as a psycho-social feeling that people are not being helped or not being helped in time.”
DOUBLING DOWN ON LOCATION
We’re rebuilding in the wrong places:
“We go through floods that create $3 billion to $4 billion of damage, like Calgary (in 2013), and then what happens is people are building in the same locations. And local governments are proud to give the support to do that.”
“To me, that’s ludicrous …”
AN INCONVENIENT TRUTH?
Climate changes are making floods a greater threat, he believes.
“We have to remember that these are natural phenomena. They are going to occur. The changing conditions are going to change (floods) and make them more endemic, more variable.”
After major European floods in 2000, countries are trying to leave extra undeveloped space around rivers, he said. But not in Canada. “We are rebuilding in the same place. We are potentially causing a problem for the next time, when the water comes again. In decision-making we are rarely bringing the climate change into the picture.”
INSURANCE INDUSTRY
The insurance industry gives funding to his research institute at Western because it wants better understanding of costly disasters — earthquakes, tornadoes and floods among them.
Fine, but what about the homes already built in floodprone zones?
Buy them up, says Simonovic. Bulldoze them. “Release that land to the river.” It’s cheaper in the long run than trying to protect them and then paying for major repairs.