Investigation of the Effects of Proposed Hurricane Protection Structures on the Characteristic Transport of Larval Fish into Lake Pontchartrain

The Hurricane Protection Office (HPO) has requested that the Engineer Research and Development Center (ERDC) investigate the effects of proposed hurricane protection structures on the transport of larval fish recruitment into Lake Pontchartrain. Although the protection of human life is the priority, environmental agencies are concerned that these structures may adversely impact the fish population in Lake Pontchartrain. ERDC has modified passive particles within the Particle Tracking Model (PTM) with characteristic larval fish transport behaviors to study the effects of the hurricane protection structures on the transport of the representative particles into Lake Pontchartrain. PTM is a Lagrangian particle tracker designed to determine the fate of discrete constituents within hydrodynamic flowfields. Particles are initiated within specified areas of the Mississippi River Gulf Outlet (MRGO), the Gulf Intercoastal Waterway (GIWW), and Lake Borgne. Hydrodynamic solutions used to drive particle transport are developed by the Adaptive Hydraulics model (ADH). Analysis is performed comparing recruitment of representative particles into Lake Pontchartrain based on construction phases, initial locations, final recruitment paths, and characteristic larval fish transport behaviors. Results show that reduction of flow within the MRGO generates alternate preferred pathways for larval fish recruitment. In addition, characteristic larval fish behaviors affect transport into recruitment zones. This study is able to give insight into the effects generated by these proposed changes to the system and how these effects may impact the fish population.