Hydrodynamic, salinity, and morphological modeling study of a sediment diversion : an application of the Adaptive Hydraulics Model/SEDLIB Sediment Transport Library

Abstract

A water diversion designed to channel sediment-rich water from the Mississippi River into Breton Sound marsh was evaluated through application of a numerical model. The model was validated to data collected from April to December 2010. After model validation was complete, simulations to understand the effects of the proposed diversion on hydrodynamics, salinity, sedimentation, and land building were conducted. Model salinity results indicate that the proposed diversion will rapidly freshen most of Breton Sound and maintain fresh water conditions in the Sound until the diversion is closed. After closure, the time of recovery of salinity in Breton Sound is a function of the prevailing winddriven currents and Mississippi River discharges through the eastern passes. With respect to the land building potential, model results indicate that the diversion has the capability to create land, but that the diversion cannot operate at full capacity for the full life cycle of the project. Deposition of sand at the diversion channel mouth creates a backwater effect that causes the water surface elevation in the outfall channel to exceed prescribed design constraints. The outfall channel mouth will therefore need to be periodically dredged and placed to form new land elsewhere in the marsh.

Real-time forecasting model development work plan

“…• AdH: 2D models for the Barataria and Breton Sound basins (Brown et al 2019a; o Versions 2: Updated and used for sensitivity analyses 10 11 12 13 o Version 3: Updated and improved to inform the Mid-Barataria Sediment Diversion Project Environmental Impact Statement (EIS) 14 o Version 4: Updated and improved to inform the Mid-Breton Sediment Diversion Project EIS These models would likely be run in series along with the Mississippi River model selected for the RTF system. There are various options for how river and receiving basin models can be coupled.…”