Paper No. JAWRA-07-0187-P of the Journal of the American Water Resources Association (JAWRA). Discussions are open until August 1, 2009.
Evidence for Changing Flood Risk in New England Since the Late 20th Century1
Version of Record online: 29 DEC 2008
© 2008 American Water Resources Association. No claim to original U.S. government works
JAWRA Journal of the American Water Resources Association
Volume 45, Issue 2, pages 279–290, April 2009
How to Cite
Collins, M. J. (2009), Evidence for Changing Flood Risk in New England Since the Late 20th Century. JAWRA Journal of the American Water Resources Association, 45: 279–290. doi: 10.1111/j.1752-1688.2008.00277.x
- Issue online: 25 MAR 2009
- Version of Record online: 29 DEC 2008
- Received December 26, 2007; accepted July 21, 2008.
Vol. 46, Issue 1, 199, Version of Record online: 1 FEB 2010
- surface water hydrology;
- climate variability;
Abstract: Long-term flow records for watersheds with minimal human influence have shown trends in recent decades toward increasing streamflow at regional and national scales, especially for low flow quantiles like the annual minimum and annual median flows. Trends for high flow quantiles are less clear, despite recent research showing increased precipitation in the conterminous United States over the last century that has been brought about primarily by an increased frequency and intensity of events in the upper 10th percentile of the daily precipitation distribution – particularly in the Northeast. This study investigates trends in 28 long-term annual flood series for New England watersheds with dominantly natural streamflow. The flood series are an average of 75 years in length and are continuous through 2006. Twenty-five series show upward trends via the nonparametric Mann-Kendall test, 40% (10) of which are statistically significant (p < 0.1). Moreover, an average standardized departures series for 23 of the study gages indicates that increasing flood magnitudes in New England occurred as a step change around 1970. The timing of this is broadly synchronous with a phase change in the low frequency variability of the North Atlantic Oscillation, a prominent upper atmospheric circulation pattern that is known to effect climate variability along the United States east coast. Identifiable hydroclimatic shifts should be considered when the affected flow records are used for flood frequency analyses. Special treatment of the flood series can improve the analyses and provide better estimates of flood magnitudes and frequencies under the prevailing hydroclimatic condition.