Flood frequency estimation and uncertainty in arid/semi-arid regions

Asher Metzger*, Francesco Marra, James A. Smith, Efrat Morin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


At site flood frequency analysis (FFA) in arid/semi-arid watersheds poses unique challenges to researchers and practitioners due to the generally limited data records. This study presents a comprehensive evaluation of FFA in arid/semi-arid watersheds in relation to the unique characteristics of these regions, such as the limited number of floods occurring each year and the large variability of the flood peak discharges. Study cases in Israel and the US are examined and compared with non-arid watersheds, characterized by Mediterranean climate, and with synthetic flood records. Results show that the tail of extreme value distributions describing arid/semi-arid watersheds is found to be heavier than the one describing Mediterranean watersheds. The number of yearly floods and the variability of flood peak discharge are shown to have a crucial impact on the accuracy of the quantile estimates with smaller number of events per year and larger coefficient of variation of flood peak discharge being related to larger errors in the estimated quantiles. Partial duration series approach provides a slightly reduced bias in the estimates, but should not be blindly preferred over annual maxima series as it presents comparable estimation uncertainty. In general, the generalized extreme value and the generalized Pareto distribution are found to be non-optimal choices for the examined arid/semi-arid watersheds.

Original languageAmerican English
Article number125254
JournalJournal of Hydrology
StatePublished - Nov 2020

Bibliographical note

Funding Information:
This study was funded by the NSF-BSF (grant BSF 2016953), by the Israel Science Foundation (grant 1069/18 ), by the BARD project (grant IS-5124-18) and by a Google gift grant. This study is a contribution to the PALEX project Paleohydrology and Extreme Floods from the Dead Sea ICDP Core and is a contribution to the HyMeX program. Data for this paper is from the US geological survey (freely available at https://waterdata.usgs.gov/nwis/rt ) and the Israel hydrological service.

Publisher Copyright:
© 2020 Elsevier B.V.


  • Annual maxima series
  • Arid/semi-arid regions
  • Extreme value theory
  • Flood frequency analysis
  • Parameter estimation
  • Partial duration series


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