Salinity Changes in Pontchartrain Basin Estuary, Louisiana, Resulting from Mississippi River-Gulf Outlet Partial Closure Plans
Salinity Changes in Pontchartrain Basin Estuary, Louisiana, Resulting from Mississippi River-Gulf Outlet Partial Closure Plans

Author:

Publisher:

Published: 2001

Total Pages: 46

ISBN-13:

DOWNLOAD EBOOK

The Mississippi River-Gulf Outlet (MRGO) consists of a ship channel 36 ft deep and 500 ft wide, extending approximately 76 miles from the junction of the Inner Harbor Navigation Canal and the Gulf Intracoastal Waterway in New Orleans, LA, to the -38 m1w (mean low water)-ft contour in the Gulf of Mexico. The purpose of the MRGO is to provide a deep draft channel to the Port of New Orleans Inner Harbor facilities. Since the MRGO's completion in January 1968, saltwater flux from the MRGO through direct connections to Lake Borgne and the Gulf Intracoastal Waterway has contributed to an increase in the salinity concentration of the lakes and Biloxi Marshes. This report presents the results of a numerical model investigation used to predict average salinity changes that will occur in the Lake Pontchartrain Basin as a result of varying levels of closure of the Mississippi River-Gulf Outlet below Lake Borgne.

Salinity Changes in Pontchartrain Basin Estuary, Louisiana, Resulting from Mississippi River-Gulf Outlet Partial Closure Plans with Width Reduction
Salinity Changes in Pontchartrain Basin Estuary, Louisiana, Resulting from Mississippi River-Gulf Outlet Partial Closure Plans with Width Reduction

Author:

Publisher:

Published: 2002

Total Pages: 42

ISBN-13:

DOWNLOAD EBOOK

The Mississippi River-Gulf Outlet (MRGO) consists of a ship channel 36 ft deep and 500 ft wide, extending approximately 76 miles from the juncture of the Inner Harbor Navigation Channel and the Gulf Intracoastal Waterway in New Orleans, LA, to the -38 mlw (mean low water) -ft contour in the Gulf of Mexico, The purpose of the MRGO is to provide a deep-draft channel to the Port of New Orleans Inner Harbor Facilities. Since the MRGO's completion in January 1968, saltwater flux from the MRGO through direct connections to Lake Borgne and the Gulf Intracoastal Waterway has contributed to an increase in the salinity concentration of the lakes and Biloxi Marshes. This report presents the results of a numerical mode investigation used to predict average salinity changes that will occur in the Lake Pontchartrain Basin as a result of varying levels of depth and width closure of the MRGO below Lake Borgne. This report follows a previous study, ERDC/CHL TR-01-14, that modeled depth closure alone, which produced very low changes in salinity.

Salinity Changes in Pontchartrain Basin Estuary Resulting from Bonnet Carre' Freshwater Diversion. Numerical Model Investigation
Salinity Changes in Pontchartrain Basin Estuary Resulting from Bonnet Carre' Freshwater Diversion. Numerical Model Investigation

Author:

Publisher:

Published: 1997

Total Pages: 90

ISBN-13:

DOWNLOAD EBOOK

One purpose of the diversion is to reduce salinities in the Biloxi Marshes by 2 to 8 parts per thousand (ppt) in order to improve oyster productivity. A range of monthly salinities has been identified as the desired product of the project. Those salinities, called the Chatry salinities in this report, consist of a narrow band of 'optimum' salinities and a somewhat wider band of 'range limits.' A time varying, three dimensional numerical model of the estuary was constructed using the U.S. Army Corps of Engineers TABS-MD modeling system. The modeled area included Lakes Maurepas, Pontchartrain, and Borgne, Biloxi Marshes, and a portion of Chandeleur Sound plus connecting waterways of Mississippi River Gulf Outlet (MRGO), Inner Harbor Navigation Canal, Gulf Intracoastal Waterway, Chef Menteur, and The Rigolets. All major tributary freshwater flows were simulated, as were tides at the Gulf of Mexico boundary and winds. The model computed instantaneous water levels and current velocities and salinities in three spatial dimensions throughout the area modeled. The model was verified to satisfactory reproduce hydrodynamic behavior observed in the natural system in 1982 and 1994. Four conditions were modeled for April through August of a typical year: a Base condition with no diversion, Plan RT with freshwater diversions up to 20,000 cfs, Plan MBP5 with freshwater diversions up to 8,500 cfs, and Plan LBCl, with no freshwater diversions but with the connections between the MRGO and Lake Borgue closed. The numerical model results were used to construct a simple regression equation that relates Biloxi Marsh salinities at a point to freshwater flows from the natural tributaries plus the diversions. The equation was then used to develop other diversion schedules that offered various salinity reduction scenarios.