Precipitation extremes

Extreme precipitation return periods

Extreme precipitation events affect numerous aspects of society and are increasing in many areas as the climate warms. The design of many hydrologic infrastructure projects is based on “design values” of precipitation, which estimate the maximum amount of precipitation that can be expected for a given recurrence interval (e.g. 50 years). These design values are typically derived from precipitation measurements at widely scattered, long-term observing sites. Using a densely-spaced network of citizen science observations in the Colorado Front Range region from the Community Collaborative Rain, Hail and Snow (CoCoRaHS) Network, my colleagues and I derived updated design values representative of a metropolitan area rather than a single point. Our area-based design values were larger than point-based values for shorter recurrence intervals but smaller for longer recurrence intervals, likely due to the relatively short duration of the CoCoRaHS record. Future work will revisit these results and expand to other metropolitan areas as the length and number of CoCoRaHS records grows.

 

Read more:

• Mattingly et al., 2017 (Annals of the American Association of Geographers): Estimates of extreme precipitation frequency in urban areas derived from spatially dense rain gauge observations: A case study of two urban areas in the Colorado Front Range region