Inferring heavy tails of flood distributions through hydrograph recession analysis

Floods are often disastrous due to underestimation of the magnitude of rare events. Underestimation commonly happens when the magnitudes of floods follow a heavy-tailed distribution, but this behavior is not recognized and thus neglected for flood hazard assessment. In fact, identifying heavy-tailed...

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Bibliographic Details
Published in:Hydrology and earth system sciences 2023-12, Vol.27 (24), p.4369-4384
Main Authors: Wang, Hsing-Jui, Merz, Ralf, Yang, Soohyun, Basso, Stefano
Format: Article
Language:English
Subjects:
Analysis
Case studies
Flood hazards
Floods
Hazard assessment
Hydrograph analysis
Hydrographs
Hydrology
Precipitation
Probability distribution
Recession
Records
River basins
Statistical methods
Stream discharge
Stream flow
Streamflow
Tails
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Summary:Floods are often disastrous due to underestimation of the magnitude of rare events. Underestimation commonly happens when the magnitudes of floods follow a heavy-tailed distribution, but this behavior is not recognized and thus neglected for flood hazard assessment. In fact, identifying heavy-tailed flood behavior is challenging because of limited data records and the lack of physical support for currently used indices. We address these issues by deriving a new index of heavy-tailed flood behavior from a physically based description of streamflow dynamics. The proposed index, which is embodied by the hydrograph recession exponent, enables inferring heavy-tailed flood behavior from daily flow records, even of short length. We test the index in a large set of case studies across Germany encompassing a variety of climatic and physiographic settings. Our findings demonstrate that the new index enables reliable identification of cases with either heavy- or non-heavy-tailed flood behavior from daily flow records. Additionally, the index suitably estimates the severity of tail heaviness and ranks it across cases, achieving robust results even with short data records. The new index addresses the main limitations of currently used metrics, which lack physical support and require long data records to correctly identify tail behaviors, and provides valuable information on the tail behavior of flood distributions and the related flood hazard in river basins using commonly available discharge data.
ISSN:1607-7938
1027-5606
1607-7938
DOI:10.5194/hess-27-4369-2023