En route to her PhD, GSO graduate student Christelle Balt, advised by Prof. Chris Kincaid, has been studying the dynamics of water movement in upper Narragansett Bay.

Of particular interest is Greenwich Bay, part of upper Narragansett Bay. The area has a history of water quality problems. Greenwich Bay is oriented generally east/west, with relatively weak currents. Balt has run experiments using the Regional Ocean Modeling System, a high-resolution computer model. She varies parameters such as winds, tides, and river runoff to see how each one affects the flow of water and flushing of constituents. Of those three, Balt discovered that the speed and direction of the wind had the greatest impact on flushing.  Balt’s modeling indicated that winds blowing from south to north would suppress the weak currents in Greenwich Bay. When that happens, bacteria or other contaminants tend to remain in the area rather than being flushed out to the lower bay and ocean.

Over the past few summers, a team of GSO oceanographers have installed five acoustic doppler current profilers and three dozen SeaHorse tilt current meters to measure currents in and around Greenwich Bay.  Balt used wind measurements from existing meteorological stations, but also augmented the observation network with wind meters. The instruments confirm Balt’s assessment – when the wind blows from south to north in Greenwich Bay, a weak eddy or gyre forms, which keeps bacteria or other contaminants trapped in Greenwich Bay.

The problems in Greenwich Bay have been particularly acute this year, with Warwick beaches being closed for a total of 60 days due to high bacterial levels. Balt believes winds from the south created a low flushing environment which permitted bacteria introduced by a series of high runoff events to remain in the area. Her work and its relevance to this year’s beach closures were noted in the Warwick Beacon.