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These are the areas of Canada most prone to flooding

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As southern Pakistan grapples with deadly flooding along the Indus River, residents of another country with a lengthy history of floods may be wondering if it could happen here.

With three coasts, and more than , significant flooding events are part of Canada鈥檚 past and its future.

They鈥檙e also Canada鈥檚 most expensive and most common natural hazards, , affecting hundreds of thousands of Canadians.

鈥淭here are urban areas across the country that all deal with flooding,鈥 Carleton University professor Jennifer Drake told CTVNews.ca in a phone interview on Friday. 鈥淏ut the causes of flooding can vary with the climate and the region.鈥

Here are the types of regions in Canada most likely to experience flooding events.

RIVER DELTAS

While many people associate the word 鈥渄elta鈥 with the Mississippi River, John Richardson, who teaches in the University of British Columbia鈥檚 department of forest conservation sciences, says Canada has many deltas, and they鈥檙e typically prone to flooding.

According to Richardson, river deltas form where the flow of a river slows as it reaches the body of water it drains into, causing that flow to spread out over a larger area and deposit sediment that eventually becomes a landmass.

鈥淢any of the places in Canada where we see big floods are largely in those delta-type areas,鈥 Richardson told CTVNews.ca in a phone interview Friday. 鈥淭he thing that鈥檚 important is to think about river deltas as not just going into the ocean. River deltas also into other rivers, into lakes and wetlands.鈥

Deltas are especially prone to flooding when water levels rise, either in the river or the body of water it鈥檚 flowing into. This flooding, he said, has caused problems for communities situated in Canadian deltas, like those in British Columbia.

FLOODPLAINS

Flat, shallow areas of land adjacent to rivers, known as floodplains, are especially prone to flooding during storms, spring ice melts or any other event that causes water levels to overtop the riverbank.

鈥淭he name says it all,鈥 Richardson said. 鈥淔loodplains were established over thousands of years from streams carrying sediment down from where it鈥檚 being eroded from.鈥

Richardson said they鈥檝e historically been attractive places to settle, since the soil in floodplains is good for farming.

鈥淪o we have had a history as humans of building into those areas.鈥

Richardson said communities situated on floodplains are threatened by water level changes caused by storms and spring ice melt, not only due to the risk of a river overtopping its banks, but because these water level changes prevent storm-water drains from properly draining, leading to urban flooding.

Several communities in Toronto were devastated by historic flooding during in October 1954. That event killed more than 80 people, left thousands homeless and destroyed bridges and roads in the west end of the city, near the Humber River floodplain.

NORTH-FLOWING RIVERS

According to Drake, spring brings additional risks for communities along rivers in the form of the freshets, or spring thaws, and accompanying . While freshets can raise water levels, ice jams create natural dams that impede the flow of water through the river.

鈥淚ce jams are when you have that surface ice on a river that breaks up and gets stuck like a log jam, and causes the water behind it to back up,鈥 said Drake, who teaches in Carleton University鈥檚 department of civil and environmental engineering. 鈥淭hese are hard to predict.鈥

Water dammed by ice jams can flow over the banks of a river, impacting nearby communities.

While ice jams can occur on any river that freezes during the winter, north-flowing rivers such as the Mackenzie River are especially prone to them. This is because upstream water to the south thaws faster than downstream water to the north, contributing to the build-up of ice jams and increasing the risk of local flooding.

Notable examples of major flooding in north-flowing rivers include the in Winnipeg, and the Red River Valley; the in Fort McMurray, Alta.; and annual flooding along the in Alberta and the Northwest Territories.

LOW-LYING COASTAL AREAS

Along Canada鈥檚 coasts, storms bring the risk of atmospheric surges that can push seawater up onto the land.

鈥淭he water level rise that happens when you have a hurricane or a large storm creates flooding or exacerbates flooding for coastal cities,鈥 Drake said.

In , a record storm surge event in New Brunswick caused more than $1.7 million in damage in communities from Shediac to Bathurst.

Richardson expects to see storm records broken with increasing regularity throughout the country as climate change intensifies.

鈥淲e all know with climate change we鈥檙e anticipating stronger storms,鈥 Richardson said. 鈥淓ven if you look at hurricane intensities, those have been increasing in average intensity for most of the last 40 years.鈥

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