Global Changes in 20-year, 50-year and 100-year River Floods

Geophysical Research Letters
By: , and 

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Abstract

Concepts like the 100-year flood event can be misleading if they are not updated to reflect significant changes over time. Here, we model observed annual maximum daily streamflow using a nonstationary approach to provide the first global picture of changes in: (a) the magnitudes of the 20-, 50-, and 100-year floods (i.e., flows of a given exceedance probability in each year); (b) the return periods of the 20-, 50-, and 100-year floods, as assessed in 1970 (i.e., flows of a fixed magnitude); and (c) corresponding flood probabilities. Empirically, we find the 20-/50-year floods have mostly increased in temperate climate zones, but decreased in arid, tropical, polar, and cold zones. In contrast, 100-year floods have mostly decreased in arid/temperate zones and exhibit mixed trends in cold zones, but results are influenced by the small number of stations with long records, and highlight the need for continued updating of hazard assessments.

Publication type Article
Publication Subtype Journal Article
Title Global Changes in 20-year, 50-year and 100-year River Floods
Series title Geophysical Research Letters
DOI 10.1029/2020GL091824
Volume 48
Issue 6
Year Published 2021
Language English
Publisher American Geophysical Union
Contributing office(s) Office of the Associate Director for Water
Description e2020GL091824, 10 p.
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