Hydrodynamic Modeling for Design of the Lower Mississippi River Louisiana International Terminal

Abstract: The Port of New Orleans is building a new international terminal called the Louisiana International Terminal (LIT) along the right descending bank of the Mississippi River (MR) near the town of Violet, Louisiana. The LIT at River Mile (RM) of 83.0, is being built approximately 16.5 miles downstream along the river, of the existing Port of New Orleans (RM 99.5), river miles being calculated from the Head of Passes. The principal advantages of this new terminal will be its ability to handle container ships of all sizes, particularly post-Panamax vessels and being downriver in its ability to can take advantage of the latest US Army Corps of Engineers (USACE) plans to dredge the MR ship channel to a minimum available draft of 50 ft. The positioning also eliminates the height restriction imposed by the Crescent City Connection. The LIT will also be protected by the USACE federal levee system and being downstream of the existing port will eliminate about 17 miles of river navigation in each direction, saving time and fuel.
FTN Associates is conducting the hydrodynamic modeling of the MR to aid in the design of the LIT. Water levels and velocity, under various MR flow conditions are being modeled using a three-dimensional (3D) Delft3D model for a 40 mile section of the MR extending from Carrollton, LA (RM 102.8) upstream to Belle Chasse, LA (RM 76.0) downstream. This stretch of the Lower Mississippi River is dominated by significant backwater effects and water levels and flows are tidally affected, making their quantification for a given flow condition complex. The 3D model has been calibrated and validated against boat based Acoustic Doppler Current Profiler (ADCP) observations. USACE channel and revetment surveys complimented by high resolution multi-beam data collected at the study site has been used to build the model bathymetry. The model will provide detailed 3D velocity measurements across the entire river and at various depths near the project site to aid in the navigation and berthing and mooring design. In addition, the velocities will be used to determine scour potential of the river bed, particularly near the bottom of the structure. This study is expected to provide insights into the hydrodynamics of Lower Mississippi River in the vicinity of a proposed port site and provide quantifiable inputs to designers.

How does this project / topic contribute to the advancement of the industry and profession?: The hydrodynamic modeling will provide insights into the complex hydraulics at play in a tidally affected backwater dominated stretch of the Lower Mississippi River, especially near a major port site to be built. The modeling methodology, development of boundary conditions from existing and collected data and analysis of results will provide a real-life example of application of the state of art hydrodynamic modeling for port design.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: Yes

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: The science of river engineering, particularly in the backwater dominated Lower Mississippi River reach needed careful model planning based on analysis of existing data and review of earlier modeling efforts. In addition, interaction with the Port of New Orleans revealed operational insights that was helpful in the modeling process, eg, choice of model duration, runtime, resolution of grid etc.

Who is the target audience for this paper?: Port engineers, civil engineers, environmental scientists, marine terminal operators, will benefit from an understanding of the modeling methodology and project outcomes.