BOTTOM SEDIMENT CHARACTERIZATION OF THE CONNECTICUT RIVER ESTUARY

A study of bottom sediment characteristics is underway as part of a senior research seminar at Boston College. This study describes the grain size and settling velocity of sediment in the Connecticut River Estuary, a microtidal, sand-dominated estuary that opens into Long Island Sound in southeast Connecticut. A total of 82 surface sediment samples were collected in four different regions of the estuary characterized by strong salinity fronts. The samples were typically greater than 50% coarse sediments, and as high as 95%. Grain size distributions within frontal zones showed high spatial variability in terms of median size and sorting and percent fine sediments. In addition to analyzing grain size, boundary shear stresses were calculated from near-bed velocity measurements. The critical shear stress was exceeded during each of the studied tidal cycles, causing sediment transport as both suspended and bedload. Magnitude and direction of transport are being determined for the different regions and compared with prior studies.