We use flood maps to assess the risk of flooding. If our home or business is located in a high flood risk area, most of us will take steps to prevent and mitigate future flood damage.
But sometimes floods occur well outside high-risk areas. In June, large parts of Alberta, Canada were hit with unexpected flooding when rivers overflowed their banks. Alberta is a useful case study in how floods can develop rapidly and unexpectedly, even in areas not prone to flooding.
The Alberta floods resulted from a convergence of several factors:
Unusual weather pattern
One of the biggest contributors to the Alberta floods was an unusual weather pattern. A moisture laden weather system became trapped between a high-pressure system to the north and the Rocky Mountains on the west. Winds blowing from the east also prevented the wet weather system from moving. As a result, this system sat in place and created a constant downpour of rain over the mountains for several days.
Saturated soil
The area had already experienced several days of thunderstorms, so the ground was saturated with moisture. In addition, much of the ground (especially at higher elevations) remained frozen just below the surface, further reducing its ability to absorb water. As a result, more water flowed into streams and rivers.
Snow melt
The constant heavy rains sped up the rate of snow melt on the mountains, further adding to the volume of water moving downstream.
Steep watershed
The shape of the land also contributed to flood conditions. The watershed area for the region is relatively long, narrow and steep. Consequently, the land has less time to absorb water, and the water travels faster, increasing its power.
It took all of these factors combined to produce severe flooding in southern Alberta. It demonstrates that, given the right set of circumstances, flooding can happen almost anywhere.
Whether your home is in a high or low risk area, a great way to mitigate flood damage is to install flood vents. Flood vents allow flood waters to move through your home, instead of creating outside pressure that can permanently damage your home’s structural integrity. Flood Solutions FEMA compliant flood vents are easy to install and guaranteed not to rust or rot. For information about our flood vents, contact us.
