The flood was natural, but was the disaster?

The Bhotekoshi flash flood in Nepal cannot simply be called a natural disaster.

Extreme floods are commonly described using annual exceedance probabilities or return periods—such as 50-, 100- or 500-year events, or even rarer ones. These terms do not tell us when a flood will occur; they describe its estimated probability and magnitude. Even rare events, therefore, need to be considered when the consequences of failure are severe.