The Dynamics of Water Exchange Between Narragansett Bay and Rhode Island Sound

Abstract

The Narragansett Bay estuary represents an important natural and economic resource. Narragansett Bay has a long history of scientific study, whichmakes it ideal for understanding the interplay between anthropogenic impacts, estuarine science and management. Over the past 40 years, numerous studies have focused on the biological and chemical processes within Narragansett Bay (e.g., Hicks, 1959; Kremer and Nixon, 1978; Pilson, 1985; Keller, 1988; Bender et al., 1989; Hinga et al., 1989; Nixon, 1997; Granger and Buckley, 1999; Keller et al., 1999; Brush, 2002; Oviatt et al., 2002; Prell et al., 2004; Bergondo et al., 2005). Regions of the bay have been instrumented for long-term monitoring projects (e.g., NB-PORTS sites; Rhode Island Department of Environmental Management buoys) and are sampled by monthly surveys with towed instruments. Observations suggest that large-scale, climate-induced changes (Hawk, 1998) have occurred and may be linked to modifications in the bay’s ecosystem (Hawk, 1998; Oviatt et al., 2002; Sullivan and Van Keuren, 2003). Anthropogenic and natural stresses are also apparent in the increasing number and severity of low oxygen events in more developed regions of the bay (Saarman et al., 2002; Bergondo, 2004; Bergondo et al., 2005; Deacutis et al., 2006; Chapters 11 and 12). Large-scale engineering projects will also have an impact; such as recent dredging of the Providence River shipping channel and a stormwater holding facility planned for Providence to reduce storm-water discharge and ultimately nutrient flux. Estuarine circulation lies at the heart of multidisciplinary approaches to coastal management. Ecosystem-based models require information on the mixing, flushing and transport of water between sub-regions of the estuary. Moreover, bio-chemical processes, such as those controlling oxygen levels within Narragansett Bay, are also influenced by how efficiently water is