A numerical investigation of salinity variations in the Barataria Estuary, Louisiana in connection with the Mississippi River and restoration activities.

A three-dimensional numerical model was applied to the Barataria Estuary in the Northern Gulf of Mexico to study its salinity variations as well as the impacts from the Mississippi River discharges and proposed river diversions. Model-observation comparison showed that the model was able to reproduce the hydrodynamic fields on subtidal to seasonal time scales. Salinity in the Barataria Estuary was high in fall and low in summer, with a greater variability in the lower estuary than the upper estuary. While salinity in the upper estuary was controlled by discharges from a local freshwater diversion, salinity in the lower estuary was mostly affected by the mixed Mississippi River water transported via the tidal inlets in the south. The correlation between Mississippi River discharge and estuarine salinity indicated that low salinity Mississippi River water could intrude into the estuary through the middle and east tidal inlets. Sensitivity tests were performed to assess the impacts from the Mississippi River discharges and proposed mid-Barataria Estuary sediment diversion. Model results illustrated that salinity in the estuary was more sensitive to an increase of Mississippi River discharge than a decrease. The proposed mid-Barataria sediment diversion was likely to induce a dramatic decrease of salinity in the lower estuary. The ecosystem consequences of the fluctuation of Mississippi River discharge as well as that of the proposed river diversions need further investigations. • Estuary salinity is highly impacted by mixed Mississippi River water from the tidal inlets. • Estuary salinity is more sensitive to a increased Mississippi discharge than an decreased one. • Proposed river diversion is likely to introduce a dramatic decrease of salinity in the lower estuary. [ABSTRACT FROM AUTHOR]