Paper No. JAWRA-11-0049-P of the Journal of the American Water Resources Association (JAWRA).Discussions are open until six months from print publication.
Increased Frequency of Low-Magnitude Floods in New England1
Article first published online: 2 DEC 2011
© 2011 American Water Resources Association
JAWRA Journal of the American Water Resources Association
Volume 48, Issue 2, pages 306–320, April 2012
How to Cite
Armstrong, W. H., Collins, M. J. and Snyder, N. P. (2012), Increased Frequency of Low-Magnitude Floods in New England. JAWRA Journal of the American Water Resources Association, 48: 306–320. doi: 10.1111/j.1752-1688.2011.00613.x
- Issue published online: 4 APR 2012
- Article first published online: 2 DEC 2011
- Received April 15, 2011; accepted September 12, 2011.
- climate variability;
- aquatic habitat;
- New England;
Armstrong, William H., Mathias J. Collins, and Noah P. Snyder, 2012. Increased Frequency of Low-Magnitude Floods in New England. Journal of the American Water Resources Association (JAWRA) 48(2): 306-320. DOI: 10.1111/j.1752-1688.2011.00613.x
Abstract: Recent studies document increasing precipitation and streamflow in the northeastern United States throughout the 20th and early 21st Centuries. Annual peak discharges have increased over this period on many New England rivers with dominantly natural streamflow – especially for smaller, more frequent floods. To better investigate high-frequency floods (<5-year recurrence interval), we analyze the partial duration flood series for 23 New England rivers selected for minimal human impact. The study rivers have continuous records through 2006 and an average period of record of 71 years. Twenty-two of the 23 rivers show increasing trends in peaks over threshold per water year (POT/WY) – a direct measure of flood frequency – using the Mann-Kendall trend test. Ten of these trends had p < 0.1. Seventeen rivers show positive trends in flood magnitude, six of which had p < 0.1. We also investigate a potential hydroclimatic shift in the region around 1970. Twenty-two of the 23 rivers show increased POT/WY in the post-1970 period when comparing pre- and post-1970 records using the Wilcoxon rank-sum test. More than half of these increases have p < 0.1, indicating a shift in flow regime toward more frequent flooding. Region wide, we found a median increase of one flood per year for the post-1970 period. Because frequent floods are important channel-forming flows, these results have implications for channel and floodplain morphology, aquatic habitat, and restoration.