Bonnet Carre' Freshwater Diversion, Lake Pontchartrain, Lake Borgne, BiloxiMarshes, Mississippi River Gulf Outlet, and the Inner Harbor Navigation Canal: An Evaluation by the Committee on Tidal Hydraulics

摘要

The USACE New Orleans District has been authorized by Congress to construct astructure at the Bonnet Carre' floodway to divert Mississippi River water into Lake Pontchartrain in order to reduce salinities in the Mississippi-Louisiana estuarine area. The District asked the Committee on Tidal Hydraulics to review information on the Bonnet Carre' Freshwater Diversion project and answer several questions: (1) Can the contribution of the MRGO-IHNC to the increase in salinity in Lake Pontchartrain and adjacent waterways be economically controlled. (2) If so, can the Bonnet Carre freshwater diversions be reduced in magnitude while still producing. This report by the Committee on Tidal Hydraulics provides three conclusions: (1) The Inner Harbor Navigation Canal (IHNC) contributes about 5 percent of the Lake Pontchartrain tidal prism but about 9 percent of the salt flux into the lake. (2) The Mississippi River Gulf Outlet (MRGO) contributes about six times as much salt to Lake Borgne as the IHNC contributes to Lake Pontchartrain. (3) Salt intrusion to Lake Pontchartrain cannot be significantly reduced by controlling flows at the IHNC connection to the lake, but construction of a sill-weir combination might alleviate the hypoxia zone that forms in Lake Pontchartrain near the airport.