Turbidity hysteresis in an estuary and tidal river following an extreme
discharge event
Abstract
Non-linear 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 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 events,
indicating that greater background turbidity due to sediment
remobilization from internal sources make inputs from high discharge
events less important at interannual time scales.