Introducing Flashiness-Intensity-Duration-Frequency (F-IDF): A New
Metric to Quantify Flash Flood Intensity
Abstract
Flash flooding is one of the most damaging weather types, yet it remains
challenging to quantify its severity. We propose a novel development –
the Flashiness-Intensity-Duration-Frequency (F-IDF) curve – to quantify
and spatially analyze flash flood intensity based on the frequency and
duration of the event. As a proof-of-concept, we mapped Contiguous US
(CONUS)-wide F-IDF values at 3,722 stream gage locations and explored
their relations with 59 basin attributes. It is found that (1)
Climatological precipitation amounts exhibit the most positive
correlation with flashiness while a basin’s drainage area is the most
negatively correlated; (2) Correlation of flashiness with basin
attributes decreases with increasing F-IDF return periods and shorter
event durations. Both aspects are attributable to the rainfall signal
overwhelming the underlying basin attributes as the intensities become
more extreme. This new term can have implications for hydrology,
especially for hydrologic modelers, decision-makers, and emergency
responders.