Interaction of Intra-Basin Ridge Restoration with Mid-Barataria Diversion Outflow

Barataria Basin, an estuarine embayment of the Mississippi River Delta Plain, has experienced 
substantial alteration of its hydrology due to levee construction and the near elimination of 
natural freshwater and sediment inputs from the Mississippi River. Planned large-scale 
restoration efforts, including the Mid-Barataria Sediment Diversion, are expected to substantially 
modify basin-wide salinity and temperature patterns, with implications for estuarine habitats and 
species. This study uses three-dimensional numerical modeling to examine how diversion 
operations, in combination with structural landscape modifications such as reconstructed marsh 
platforms and ridge-like features, influence salinity and temperature dynamics within Barataria 
Basin during a high Mississippi River flood year.

Model simulations indicate that operation of the Mid-Barataria Sediment Diversion produces 
widespread freshening across most of the basin, an effect enhanced by coastal circulation that 
transports freshwater from the Mississippi River’s Birdsfoot Delta into southeastern Barataria 
Bay. The southwestern portion of the basin remains relatively saline due to partial isolation by 
existing wetlands and remnant natural ridges. Following diversion shutdown, basin salinity 
generally returns to baseline conditions over timescales of weeks, with recovery dependent on river discharge, diversion duration, rainfall, and wind forcing.

Scenario testing of alternative ridge alignments demonstrates that strategically placed structural 
features can amplify spatial heterogeneity in salinity by modifying hydrologic connectivity. A 
ridge constructed along the western basin margin enhances isolation of the southwestern sub-basin, increasing salinity and altering habitat suitability for multiple species. In contrast, eastern ridge configurations produce weaker effects due to their limited continuity and the persistence of 
open-water connections that promote mixing. Habitat suitability analyses suggest that diversion 
impacts and ridge-induced modifications vary by species and season, with stronger effects during 
periods of high river discharge and limited influence on species dependent on late summer and 
fall conditions.

Together, these results suggest that combining sediment diversion operations with targeted 
structural landscape modifications can be used to manage salinity patterns and create a mosaic of 
estuarine habitats within Barataria Basin. This integrated approach offers a potential framework 
for enhancing ecological refugia and aligning restoration actions with species-specific habitat 
requirements under future diversion scenarios.