Development and Validation of 954-Mile Lower Mississippi River 2D Model

A two-dimensional adaptive hydraulics (AdH) hydrodynamic model has been developed of the entire Lower Mississippi River (LMR). This large-scale model spans levee to levee for a total of nearly 1,000 river miles, with an upstream boundary at the Ohio River confluence at Cairo, Illinois, and a downstream boundary extending into the Gulf of Mexico. The model mesh captures the main channel, floodplain, and significant tributaries within the LMR. The mesh covers an area of over 22,000 square miles and contains nearly 1.3 million nodes. Bathymetry used in the model consists of 2023 single and multi-beam surveys provided by the US Army Corps of Engineers Memphis, Vicksburg, and New Orleans districts. The model length encompasses approximately 50 gage locations which were used for the hydrodynamic model validation along with continuous water surface profiles throughout the LMR. A model of this scale provides the ability to analyze the effects of different hydrodynamic conditions from a systemwide perspective, as opposed to the more common reach by reach scale analysis. This model is adaptable for a variety of applications and is already planned to be utilized for future efforts. Future applications of this model include evaluating batture roughness effects on flowlines and flood attenuation throughout the LMR along with being the basis for the development of an operational low water model to better predict and forecast navigational depths throughout the LMR.