Mississippi River Port Dynamics At West Memphis

The City of West Memphis, Arkansas owns a port located along the Mississippi River designed to support industrial transport and commerce in the region (oil and gas, fertilizer, construction, agriculture). Due to site specific hydrodynamics and resulting stream bank migration, conditions have become very difficult and even dangerous for barge operators to navigate into and out of the port above a river flow of 900,000 cfs. During the years 2020 and 2021 the port was closed more than six months each year which significantly impacts the economy of West Memphis.

The City of West Memphis hired HDR to perform a planning study to investigate the underlying cause of the dangerous docking conditions, recommend short and long term solutions, and test the efficacy of the solutions. Any modification to the project will require coordination and compliance with floodplain regulations, local and federal levee approvals, cooperation with USACE bank repair and stabilization program as well as the USACE Navigation project under Section 408.

The technical evaluation has showcased bathymetric data collection, sedimentation considerations, leveraging reach scale 1D models for development of boundary conditions, a HEC-RAS 2D model for concept development and evaluation, and a FLOW-3D CFD model to further investigate the complex hydrodynamic condition under both existing conditions and with the selected alternatives.

The 2D HEC RAS model and the FLOW-3D model were validated to the extent possible with USACE collected ADCP velocity transects collected upstream and downstream of the port at various flow rates, USGS gage data and aerial imagery. This provided insight into how well each model performs as well as understanding limitations associated with each solution scheme for capturing the locations of flow separations, shear layers and the transient behavior of these hydrodynamics. An initial group of more than 12 hydraulic alternatives, ranging from spur-dikes to protective dolphin removal was narrowed down through HEC-RAS 2D modeling and a smaller group of the most effective solutions were modeled using the CFD model.

The port improvement study has been performed at the same time as a USACE bank repair and stabilization project in the reach which has provided some unique opportunities to take advantage of and enhance of each organizations mission.

Ultimately this study has leveraged the available state of the art technology to solve a practical problem in very complex conditions. It also demonstrates the level of cooperation and engagement required by local, state, and Federal governments to solve these challenging problems.