Flood management is a priority for many governments around the world. Recent floods have led to hundreds of deaths and caused significant damage in Indonesia, Sri Lanka, Thailand, Vietnam, Albania, Kenya and elsewhere.

Canada too is no stranger to floods. Notably, in 2021, flooding in British Columbia cut off access to Metro Vancouver from the rest of the country and caused up to $14 billion in damages.

While many scientific and technical reports show that floods are becoming larger and more common, these reports may be underestimating how their frequency is changing. Flood sizes get the spotlight, however governments and experts need to also consider their frequency to address implications overlooked by traditional management methods.

Frequency and size together must tell the story, because even modest increases in size can lead to surprisingly big jumps in frequency. For example, timber harvesting in the B.C. Interior has led to a 19 to 26 per cent increase in flood size, and turned the former 100-year flood into a once-a-decade flood. Despite floods becoming more frequent, today’s practices still dominantly focus on flood size.

The consequences........

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