Rapid response of New England (USA) rivers to shifting boundary conditions: Processes, time frames, and pathways to post-flood channel equilibrium

摘要

The time scale of channel recovery from disturbances indicates fluvial resiliency. Quantitative predictions of channel recovery are hampered by multiple possible recovery pathways and stable states and limited long-term observations that provide benchmarks for testing proposed metrics. We take advantage of annual channel-change measurements following Tropical Storm Irene's 2011 landfall in New England (eastern USA) to document geomorphic recovery processes and pathways toward equilibrium. A covariate metric demonstrates that channels can adjust rapidly to ongoing boundary condition shifts, hut that they adjust along a continuum of possible stable states. Moreover, the covariate equilibrium metric indicates sensitivity to warm-season high discharges that, in this region, are increasing in frequency. These data also show that the channels are resilient in that they are able to recover an equilibrium form within 1-2 yr of disturbances.