Trends in Rainfall Exceedances in the Observed Record in Selected Areas of the United States1

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.

High-Resolution Downscaled Simulations of Warm-Season Extreme Precipitation Events in the Colorado Front Range under Past and Future Climates*

“…1). Here, we take extreme to indicate the largest daily precipitation events in the available RCM datasets but acknowledge that semantics to describe such events may differ in engineering and stakeholder communities (e.g., Bonnin et al 2011). Precipitation totals from June, July, and August were ranked according to the largest 24-h precipitation (1500-1500 UTC) total at any one RCM grid point in the target region [note that increasing the area over which precipitation was averaged to rank events (to a moving region with dimensions 200 km 3 200 km within the target region) did not significantly alter the resulting rank order].…”

Probable maximum precipitation and climate change

“…[3] Increases in heavy precipitation events have been documented in many regions of the globe [IPCC, 2012] with substantial variations in the spatial distribution of statistically significant trends [Bonin et al, 2011;Kunkel et al, 2013]. Similarly, most areas of the U.S. are projected to see increases through the 21 st century [IPCC, 2012], including areas that did not have statistically significant trends in the 20 th century.…”

Adapting bridge infrastructure to climate change: institutionalizing resilience in intergovernmental transportation planning processes in the Northeastern USA

“…Yet, another knowledge gap relates to semantic differences in the terms and methods of analysis used by climate scientists versus those employed by civil engineers. While climate scientists are typically focused on trends in magnitudes of precipitation and flooding, engineers may be more concerned with changes in the number of exceedances (Bonnin et al 2001).…”