Modeling tidal exchange and dispersion in Boston Harbor

Journal of Geophysical Research C: Oceans
By:  and 

Links

Abstract

Tidal dispersion and the horizontal exchange of water between Boston Harbor and the surrounding ocean are examined with a high-resolution (200 m) depth-averaged numerical model. The strongly varying bathymetry and coastline geometry of the harbor generate complex spatial patterns in the modeled tidal currents which are verified by shipboard acoustic Doppler surveys. Lagrangian exchange experiments demonstrate that tidal currents rapidly exchange and mix material near the inlets of the harbor due to asymmetry in the ebb/flood response. This tidal mixing zone extends roughly a tidal excursion from the inlets and plays an important role in the overall flushing of the harbor. Because the tides can only efficiently mix material in this limited region, however, harbor flushing must be considered a two step process: rapid exchange in the tidal mixing zone, followed by flushing of the tidal mixing zone by nontidal residual currents. Estimates of embayment flushing based on tidal calculations alone therefore can significantly overestimate the flushing time that would be expected under typical environmental conditions. Particle-release simulations from point sources also demonstrate that while the tides efficiently exchange material in the vicinity of the inlets, the exact nature of dispersion from point sources is extremely sensitive to the timing and location of the release, and the distribution of particles is streaky and patchlike. This suggests that high-resolution modeling of dispersion from point sources in these regions must be performed explicitly and cannot be parameterized as a plume with Gaussian-spreading in a larger scale flow field.

Study Area

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Modeling tidal exchange and dispersion in Boston Harbor
Series title Journal of Geophysical Research C: Oceans
DOI 10.1029/92JC01429
Volume 97
Issue C10
Year Published 1992
Language English
Publisher American Geophysical Union
Publisher location Richmond, VA
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 16 p.
First page 15591
Last page 15606
Country United States
State Massachusetts
City Boston
Other Geospatial Boston Harbor
Online Only (Y/N) N
Additional Online Files (Y/N) N