Sediment transport due to extreme events: The Hudson River estuary after tropical storms Irene and Lee

Tropical Storms Irene and Lee in 2011 produced intense precipitation and flooding in the U.S. Northeast,
including the Hudson River watershed. Sediment input to the Hudson River was approximately 2.7 megaton, about
5 times the long-term annual average. Rather than the common assumption that sediment is predominantly trapped
in the estuary, observations and model results indicate that approximately two thirds of the new sediment
remained trapped in the tidal freshwater river more than 1 month after the storms and only about one fifth of
the new sediment reached the saline estuary. High sediment concentrations were observed in the estuary, but
the model results suggest that this was predominantly due to remobilization of bed sediment. Spatially localized
deposits of new and remobilized sediment were consistent with longer term depositional records. The results
indicate that tidal rivers can intercept (at least temporarily) delivery of terrigenous sediment to the marine
environment during major flow events.