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Trends in Rainfall Exceedances in the Observed Record in Selected Areas of the United States

Authors

  • Geoffrey M. Bonnin,

    1. Respectively, Chief, Hydrologic Science and Modeling Branch, Office of Hydrologic Development, National Weather Service, National Oceanic and Atmospheric Administration, W/OHD, 1325 East West Highway, Silver Spring, Maryland 20910
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  • Kazungu Maitaria,

    1. Research Scientist, University Corporation for Atmospheric Research, Boulder, Colorado 80307 and Office of Hydrologic Development, National Weather Service, National Oceanic and Atmospheric Administration, Silver Spring, Maryland 20910
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  • Michael Yekta

    1. Information Technology Specialist, Office of Hydrologic Development, National Weather Service, National Oceanic and Atmospheric Administration, Silver Spring, Maryland 20910
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  • Paper No. JAWRA-10-0059-P of the Journal of the American Water Resources Association (JAWRA). Discussions are open until six months from print publication.

  • Editor's note: This paper originally was part of a Featured Collection on Nonstationarity, Hydrologic Frequency Analysis, and Water Management, published in the June 2011 issue. It was not completed in time for the issue and is presented here. See the June 2011 issue for the introduction and background to the collection.

(E-Mail/Bonnin: geoffrey.bonnin@noaa.gov)

Abstract

Bonnin, Geoffrey M., Kazungu Maitaria, and Michael Yekta, 2011. Trends in Rainfall Exceedances in the Observed Record in Selected Areas of the United States. Journal of the American Water Resources Association (JAWRA) 47(6): 1173–1182. DOI: 10.1111/j.1752-1688.2011.00603.x

Abstract:  Semantic differences have led to a gap in the understanding of the impacts of climate change on precipitation frequency estimates. There is popular perception that heavy rainfalls have become more frequent, and that this trend will increase with global warming. Most of the literature examines this question from the point of view of climatology using definitions of “heavy,”“very heavy,” or “extreme” rainfall, which are different from those commonly used by civil engineers. This article identifies the differences in meaning used by the climate and civil engineering communities and examines trends in the observed record in the frequency of exceedances (not trends in magnitudes). Using concepts recognized as the basis for design of the Nation’s civil infrastructure, we look at trends in the number of exceedances of thresholds for a variety of precipitation frequencies and event durations used by civil engineers. We found that the estimated trends in exceedances at one-day and multiday durations were statistically significant and increasing for the Ohio River Basin and surrounding states but the reverse was true for the Semiarid Southwest (i.e., not significant and decreasing trends). In addition, we found the magnitude of the trends was small for all but the more frequent events and also small with respect to the uncertainty associated with the precipitation frequency estimates themselves.

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