23 Apr 2020

PUBLICATION NOTICE: A Comparison of GenCade,  Pelnard-Considere, and LITPACK

PURPOSE: The purpose of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to investigate the basic physics and numerical code of GenCade by running a series of simplified test cases and comparing the results to another numerical shoreline evolution model and an analytical solution. The complementary numerical code is the widely used shoreline evolution model LITPACK. The analytical model is the original solution derived by Pelnard-Considere (1956). The underlying assumption in all three approaches is a beach profile of constant shape so that shoreline change is driven by long-shore transport processes and a combination of independent sediment sources or sinks (e.g., sea level change, subsidence). The CHETN presents a descriptive overview of the theory behind the models followed by an inter-comparison using a set of four test cases involving shoreline change in the vicinity of idealized coastal structures and a beach nourishment. GenCade shows good agreement with LITPACK, and both models compare well to the analytical solution for these idealized cases. The GenCade results indicate that the underlying numerical code and basic physical process are consistent with other widely used shoreline modeling systems.

14 Apr 2020

PUBLICATION NOTICE: Numerical Sedimentation Investigation Mississippi River Cairo to Pilots Station

Report Number: MRG&P Report No. 30 Title: Numerical Sedimentation Investigation Mississippi River Cairo to Pilots Station By Ronald R. Copeland, Leslie Lombard, Roger A. Gaines Approved for Public Release; Distribution is Unlimited February 2020 Abstract:  A HEC-6T numerical model of the entire Lower Mississippi River between the end of Southwest Pass and the confluence of the Ohio River was developed. The model, which included over 1000 river miles, was calibrated to 1991-2002 measured data. The purpose of the numerical sedimentation model was to provide a tool to evaluate the long-term and system –wide effects of specific Mississippi River and Tributaries Project features. Model applications related to the effects of sediment diversions and the effects of dredging in the New Orleans District were demonstrated. The model demonstrated the effects of new constrictive works on the long-term and short-term river morphology. The model was used to test the effects of changes in upstream sediment inflow. The model’s ability to assess the effects of natural geomorphic changes, such as erosion of hard points, was demonstrated. Future application of this model to specific project sites should include the addition of more detailed geometry in the area of interest. 230 pages / 7.8 Mb