Variability in Water Column Stratification during Low Flow Conditions in the Thames River Estuary Connecticut from 2006-2015

Determining water column stratification in an estuary, such as the Thames River, is important for understanding the chemical transport (e.g., nutrients) and biological activity (e.g. phytoplankton blooms) of the system. The Thames River estuary experiences variability in stratification classification from a partially mixed to a salt wedge estuary. The physical characteristics of the system are affected by both tidal and non-tidal factors. While freshwater discharge into the system generally plays the largest role in stratification, tides and wind-driven circulation also affect the stratification of the Thames River estuary. Profiles of temperature and salinity were collected using YSI sondes at multiple stations along the Thames River estuary from New London to Norwich, CT, approximately 10 miles. Data sets were collected in September and October from 2006 to 2015. By examining the variations in salinity stratification along the length of the estuary during the low flow months over several years, the influence of tidal and wind mixing can be observed in the system. The salinity stratification was determined for each station and variations in the salinity stratification versus location along the length of the estuary were observed for the flooding and high tides versus ebbing and low tides. Analysis with wind direction also showed increased stratification under down estuary wind conditions. Understanding the response of stratification to tidal and wind forcing under low flow conditions provides a window into the influence the physical characteristics have on the biological and chemical components of the Thames River estuary.