Turbidity Hysteresis in an Estuary and Tidal River Following an Extreme Discharge Event

Abstract

AbstractNonlinear turbidity‐discharge relationships are explored in the context of sediment sourcing and event‐driven hysteresis using long‐term (≥12‐year) turbidity observations from the tidal freshwater and saline estuary of the Hudson River. At four locations spanning 175 km, turbidity generally increased with discharge but did not follow a constant log‐log dependence, in part due to event‐driven adjustments in sediment availability. Following major sediment inputs from extreme precipitation and discharge events in 2011, turbidity in the tidal river increased by 20–50% for a given discharge. The coherent shifts in the turbidity‐discharge relationship along the tidal river over the subsequent 2 years suggest that the 2011 events increased sediment availability for resuspension. In the saline estuary, changes in the sediment‐discharge relationship were less apparent after the high discharge events, indicating that greater background turbidity due to internal sources make event‐driven inputs less important in the saline estuary at interannual time scales.