The New England region in the Northeast U.S. receives high annual
precipitation as rain and snow, which results in floods that endanger
people and infrastructure. Owing to the complexity of hydrologic
systems, increases in the frequency and intensity of large precipitation
events do not always translate into increases in surface runoff measured
as event flow at the basin outlet. However, recent studies have
recognized positive trends in the frequency and magnitude of high-flow
events in New England. For high-flow events of equal or greater than
2-year daily runoff, the runoff coefficients, or the fraction of
precipitation converted into surface runoff during an event, were
determined for 28 undisturbed New England basins with natural flow
conditions. Results indicated that runoff coefficients increase in
magnitude and variability with distance from the Atlantic coast toward
the north and west. The average runoff coefficient of high-flow events
across all basins is 0.90, while there exist many high-flow events with
runoff coefficients greater than one. Also, runoff coefficients were
generally stationary showing that flood events in undisturbed basins
have remained proportional to precipitation inputs, despite increases in
extreme precipitation, possibly due to shifts in evapotranspiration,
snowpack, and soil moisture. Flood management efforts should continue to
focus on large springtime precipitation events, which generate the
highest runoff coefficients. Finally, this study can serve as a
reference point for future exploration of the flood susceptibility of
basins with anthropogenic alterations like dam construction or land use
change.