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

Abstract

[1] 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.

Model Behavior and Sensitivity in an Application of the Cohesive Bed Component of the Community Sediment Transport Modeling System for the York River Estuary, VA, USA

“…Tidal asymmetries in vertical velocity and suspended-sediment profiles can also produce ETMs [9,17,18]. Although these processes tend to be most important near the head of salt, they can create ETMs in other areas where the channel geometry alters the salinity field, often called Secondary Turbidity Maxima or STMS [19][20][21][22]. Hydrodynamic forces and sediment and bed properties influence both ETMs and STMs, and because these factors vary with time and in all three spatial dimensions, they are difficult to study using field measurements alone.…”

Three‐Dimensional Sediment Dynamics in Well‐Mixed Estuaries: Importance of the Internally Generated Overtide, Spatial Settling Lag, and Gravitational Circulation

“…In section 5.1, the sensitivity to the sediment grain size is studied by considering a grain size of 10 μ m (fine‐grained sediments) and 40 μ m (relatively coarse‐grained sediments), corresponding to a settling velocities of 0.2 mm s −1 and 1 mm s −1 (Fredsøe & Deigaard, ), respectively. The settling velocity 0.2 mm s −1 (for the first sensitivity experiment) is at the lower limit of those used for the Hudson River estuary (Ralston et al, ), and may be not typical in the Delaware estuary. Nevertheless, the sensitivity experiments aim to investigate the influence of the sediment settling velocity on the sediment transport/trapping mechanisms, and will provide useful insight into the spatial sorting of sediments of different grain‐sizes observed in many estuaries.…”

Contrasting styles of Hurricane Irene washover sedimentation on three east coast barrier islands: Cape Lookout, North Carolina; Assateague Island, Virginia; and Fire Island, New York

“…2). Intense rainfall from the storm resulted in record flooding and sediment mobilization in the U.S. Northeast (Ralston et al, 2013;Magilligan et al, 2015;Yellen et al, 2014).…”