NUMERICAL MODELING OF MOBILE-BED HYDRODYNAMICS OF THE LOWER MISSISSIPPI RIVER

摘要

The coastal wetlands of Louisiana have been adversely impacted by levees and other anthropogenic changes along the Mississippi River (MR) which have reduced the sediment delivery to the coast. One and three dimensional models of hydrodynamics and sediment transport have been implemented to quantify the potential riverine responses to re-connecting the river to the wetlands. The 1-D (HEC-RAS) model predicts riverine and sediment impacts over 475 kilometers and several years. The 3-D model (FVCOM) analyzes complex flows at the local scale near potential diversion sites. The study domain extends from Tarbert Landing to the Gulf of Mexico. The 3-D model was calibrated against field measurements and was able to reproduce the secondary flow at a bend. The hydrodynamics and sediment transport modules of HEC-RAS were also calibrated and showed good agreement with field data. The Engelund-Hansen sediment load model in HEC-RAS gave the best estimate of the bed material load.