Seasonal and tidal variations of sediment transport patterns in the Saint John Inner Harbour
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Date
2012
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University of New Brunswick
Abstract
The Saint John Harbour is located along the Bay of Fundy in southern New Brunswick
and serves as the primary outlet for the Saint John River. Sediment movement
within the Saint John Harbour is a concern from both an ecological and operational
perspective. Seasonal measurements of current velocity and suspended sediment
concentration (SSC) have been obtained by deploying two acoustic Doppler current
profilers ( ADCPs) in the inner harbour. ADCP observations spanned several months
and were nearly continuous, thus allowing for an in-depth analysis of meteorological
and tidal influences on observed hydrodynamics. A comparative assessment was
conducted for spring and neap tides, storm surges, and changes in fluvial input. It
was observed at both deployment locations that the intruding salt wedge frequently
contained high SSC. The salt wedge is believed to be a major contributor of sediment
accretion in the inner harbour, particularly during winter storm surges when river
discharge is reduced. The Courtenay Bay Channel was observed to be more sensitive
to river level, with only winter storms resulting in a landward average sediment flux.
Observations made near Courtenay Bay Channel also suggested the presence of a
cross channel flow pattern from an adjacent inter-tidal mudflat. This cross channel
flow was only observed during spring freshet conditions and contained high SSC.
Hydrodynamic observations from the study were compared with published estuarine
theory. Results of the study will help to further define hydrodynamic processes in
the Saint John Harbour.