BEDLOAD SEDIMENT TRANSPORT IN THE CONNECTICUT RIVER

The Connecticut River flows from the Connecticut Lakes to Long Island Sound, traversing approximately 410 miles. In this study, bedload sediment transport through the Glastonbury meanders was analyzed. A Datasonics SIS-1000 sidescan sonar with sub-bottom profiler was used to map the bedform fields located between Rocky Hill and Hartford, Connecticut during periods of high and low discharge. During the spring survey of April 2010, discharge exceeded 880 m3/s, while during the summer survey of July 2010 discharge was less than 200 m3/s. Discharge measurements were obtained at various cross-sections throughout the Glastonbury Meanders using a Teledyne RDI 1200-kHz acoustic Doppler current profiler (aDcp). Additional aDcp-ing was done in November 2010 to measure the flow velocity directly over six major bedform fields discovered during the spring and summer surveys. The six bedform fields we chose to examine more closely contained sedimentary features ranging in size from less than 0.5 meters to nearly 2 meters in height, and had wavelengths ranging from less than 5 meters to over 100 meters. One hundred and forty sediment samples were gathered by experienced SCUBA divers from the six aforementioned regions. Although grain size analysis is not yet complete, we are currently assuming a mean grain size of approximately 250 µm as we begin to model our findings. Our data show that during the spring freshet, bedform fields became washed out, and were able to reform during the following months as flow velocities decreased. These sedimentary features serve as micro-ecosystems for fish and plant-life, and the sediment they are comprised of may potentially transport contaminants.