Land use and climate change could increase flood frequency, Canada experts say.

Residents of B.C.’s Okanagan Valley spent much of this week preparing for unprecedented levels of flooding — but it’s far from the last time they’ll have to do so.

As global temperatures continue to rise, studies have shown an increase in extreme weatherExtreme weather describes weather phenomena that are at the extremes of the historical distribution, especially severe or unseasonal weather. (UKCIP) and predict that trend will continue.

And as development continues to occur in and around floodplains, experts say the result is that communities are increasingly at risk of floodingThe overflowing of the normal confines of a stream or other body of water, or the accumulation of water over areas that are not normally submerged. Floods include river (fluvial) floods, flash floods, urban floods, pluvial floods, sewer floods, coastal floods, and glacial lake outburst floods ...

Much of the Kelowna’s downtown is built on a floodplain, Todd Cashin, the city’s manager of suburban and rural planning told CBC News on Thursday.

Hans Schreier, professor emeritus in the department of land and waterClimate change is expected to exacerbate current stresses on water resources from population growth and economic and land-use change, including urbanisation. On a regional scale, mountain snow pack, glaciers and small ice caps play a crucial role in freshwater availability. Widespread mass ... systems at the University of British Columbia, says future development needs to take more prevalent extreme weatherWeather refers to the state of the atmosphere with regard to temperature, cloudiness, rainfall, wind, and other meteorological conditions. (UKCIP) into account.

“We need to really rethink our land useLand use refers to the total of arrangements, activities, and inputs undertaken in a certain land cover type (a set of human actions). The term land use is also used in the sense of the social and economic purposes for which land is managed (e.g., grazing, timber extraction, and conservation). ... policies and we need to change the way we develop the floodplains, because these extreme events will obviously be the norm,” Schreier said.

search and rescue

Various climate changeClimate change is a lasting change in weather patterns over long periods of time. It can be a natural phenomena and and has occurred on Earth even before people inhabited it. Quite different is a current situation that is also referred to as climate change, anthropogenic climate change, or ... effects will lead to more frequent, more prolonged extreme rainfall events, studies suggest. (Kamloops SAR/Facebook)

Warmer air means more moisture

An increasing body of scientific evidence shows that human-driven climate change is leading to more frequent severe weather events — including snowfall.

Warmer air can hold more moisture, Schreier said, which leads to more precipitationNo reegle definitive available.. But that’s not the whole story.

In a 2012 paper, Kevin Trenberth — a climate scientist at the National Center for Atmospheric Research in Colorado — found that, as average temperatures rise, we should expect to see record levels of precipitation more often.

As well, a 2017 study lead by Michael Mann of the Earth System Science Center at Penn State University found that human activity is altering the behaviour of the jet stream — a sort of atmospheric conveyor belt that moves heat and moisture around the northern hemisphere — in a way that is causing storm systems to stall more often.

These stalled systems result in longer bouts of extreme weather, both wet and dry.

All of this is to say that prolonged, record-breaking storm systems — like those that have caused flooding across the country this week — are only going to become more common.

Kelowna Floods 2017

Experts say increased development in floodplains means reduced absorptive capacity — and more people in harm’s way when floodingsee flooding inevitably occurs. (Christer Waara/CBC)

City on a floodplain

But more precipitation is only part of the picture. Schreier said a propensity to develop floodplains and areas adjacent to floodplains not only put more people in harm’s way, but also reduces the natural capacity of the land to store water without flooding.

“When we pave everything and compact all the soils, the water can no longer infiltrate, which means it’s going to run off the surface,” Schreier said.

The effect is compounded, Schreier said, by forest fires — which, though a natural part of the forest life cycle, are also becoming more common.

“Once you have fires, you have hydrophobicity, which is [when] the soil becomes water-repellant, and then you have more surface runoff.”

Kelowna Floods 2017

Hans Schreier says the effects of climate change are already upon us. (Tina Lovgreen/CBC)

Later is now

These are all things scientists have known for some time, but they don’t seem to have become common knowledge yet.

Schreier has an idea as to why that might be.

“I think we have made a big mistake [as scientists] by telling everybody that [climate change means] it’s going to get two to three degrees warmer on average,” he said. “What we should have told people is, it’s going to get more extreme.”

Schreier says preparations need to be made now, because climate change is already here.

“People think of climate change as [something that’s] going to happen down the roadA road is a thoroughfare, route, or way on land between two places, which has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways (British English: carriageways) each with one or more ..., but this is clearly evidence that it’s happening now,” he said.

“We need to really wake up and prepare ourselves.”

With files from CBC Radio One’s The Early Edition.

Powered by WPeMatico

Leave a Reply

Be the First to Comment!

Notify of
Translate »