Counting the days: A new way to measure disaster impact
UBC sociology researchers have developed a new way to measure the burden that disasters place on communities: person-days under evacuation.
When wildfires and floods hit, the first numbers we hear about are economic losses: homes destroyed, roads washed out, insurance claims piling up.
But UBC sociology researchers have developed a new—and perhaps better—way to measure the burden that disasters place on communities: person-days under evacuation.
This simple but revealing metric calculates the number of people affected by a mandatory evacuation order multiplied by the number of days the order was in place. For example, if 1,000 people were under an evacuation order for 10 days, that equals 10,000 person-days.
Using this approach, assistant professor Dr. Ethan Raker and PhD candidate Xueqing Zhang tracked every wildfire and flood evacuation order in B.C. from 2017 to 2023 and found that communities spent a staggering 2.71 million person-days under mandatory evacuation orders. That’s the equivalent of one person being displaced for 7,400 years.
Why does it matter?
Traditional disaster metrics miss a big part of the story because they focus on property damage or immediate casualties. By measuring how many people face displacement and for how long, this new approach paints a clearer picture of the human cost of disasters.
The metric also allows for apples-to-apples comparisons between regions—the recent L.A. wildfires and B.C.’s West Kelowna wildfire in 2023, for example. It could be used worldwide to compare disasters across regions, improve evacuation planning and anticipate relief needs.
Who’s hit hardest?
Disaster evacuations don’t affect communities equally. By combining evacuation data with census data, the researchers also learned that Indigenous and lower-income communities in B.C. were more likely than others to face evacuations, especially from flooding. With climate change increasing the frequency and severity of these events, that raises questions about equity in disaster preparedness and response.
Dr. Ethan Raker is available for phone or Zoom interviews. Please contact Erik Rolfsen at erik.rolfsen@ubc.ca to arrange.
