Abstract
Understanding spatiotemporal patterns of salinity in Barataria Basin in coastal Louisiana is important to better understand and manage operations of existing and proposed freshwater and sediment diversions from the Mississippi River into the estuary. In this study, a comprehensive salinity dataset was compiled which covered the entire basin and included data from 1990 through 2015. The data were aggregated into daily mean salinity timeseries across Barataria Basin at a variety of spatial scales and used to analyze historic patterns. Simulations were conducted with two hydrodynamic models, the Integrated Compartment Model (ICM) and Delft3D. The Delft3D model output was overlaid with observed geo-tagged locations of bottlenose dolphins that were sampled from the southwest quadrant of the basin. The ICM simulations were used to assess the impact of existing freshwater and proposed sediment diversion projects which reintroduce riverine water into the estuary. The salinity in the uppermost portions of the basin is sensitive primarily to the existing freshwater diversion, whereas additional flows from a proposed sediment diversion result in additional freshening. The lowermost region of the basin is most sensitive to the proposed sediment diversion; however, the magnitude varies by diverted flow volumes and assumed sea levels in the Gulf of Mexico.
Highlights
Barataria Basin is an estuary located west of the Mississippi River delta, which is wetland dominated (Figure 1)
Based upon the 8 ng/kg threshold analysis of continuous salinity observational data, there is a distinct area in the southwestern portion of Barataria Basin, west of the observational data, there is a distinct area in the southwestern portion of Barataria Basin, west of Barataria Waterway, in which salinity values remain elevated with limited periods of freshening the Barataria Waterway, in which salinity values remain elevated with limited periods of freshening relative to the rest of Barataria Basin
Of the five scenarios analyzed hindcast periodofprovides a comparison to the the historic observational data thatwith can the bestICM, lead the to an assessment the model performance in historic observational data that can best lead to an assessment of the model performance in the the Barataria Basin
Summary
Barataria Basin is an estuary located west of the Mississippi River delta, which is wetland dominated (Figure 1). Human impacts have caused a variety of changes to salinity throughout the basin with levees reducing fresh water input and canals allowing for added saltwater intrusion [4,5]. Land loss through direct and indirect human action is drastically changing the structure of the basin and in turn the salinity [5,6]. Restoration projects such as current and proposed diversions will reintroduce fresh water into the basin, pushing the saline water further south while maintaining and growing land areas [1,5]. Inoue et al [1] found that the mid-basin region with the steepest salinity gradients was impacted the most by diversions
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