Миссисипи-Кольповой Канал: Тарихы мен Салдары

Former canal in Louisiana, United States

The Mississippi River–Gulf Outlet Canal (abbreviated as MRGO or MR GO) is a 76 mile (122 km) channel constructed by the United States Army Corps of Engineers at the direction of Congress in the mid 20th century that provided a shorter route between the Gulf of Mexico and New Orleans' inner harbor Industrial Canal via the Intracoastal Waterway. In 2005, the MRGO channeled Hurricane Katrina's storm surge into the heart of Greater New Orleans, contributing significantly to the subsequent multiple engineering failures experienced by the region's hurricane protection network. In the aftermath the channel was closed. A permanent storm surge barrier was constructed in the MRGO in 2009, and the channel has been closed to maritime shipping. The MRGO begins just west of I 510's crossing of the Gulf Intracoastal Waterway in New Orleans East and takes a path SSE through St. Bernard Parish wetlands just west of Lake Borgne to the Gulf of Mexico near Gardner Island. Much criticized for its negative environmental effects, such as saltwater intrusion, wetlands erosion and storm surge amplification during Hurricane Katrina, the MRGO was closed in 2009. Maritime traffic was barred on April 22, 2009.

Conceptually, the MRGO was first envisioned early in the 20th century as a way to provide shipping with a shorter route to the Gulf of Mexico. The Port of New Orleans felt increasingly disadvantaged by the length of time oceangoing vessels needed to navigate the twists and turns of the Mississippi River from the Gulf to the port's wharfs, versus the much closer proximity to open water offered by its emerging competitors. The modern Port of Houston, in particular, came into being as a consequence of the completion of the Houston Ship Channel in 1914. New Orleans' initial response debuted in 1923, with the inauguration of the Industrial Canal linking the Mississippi River and Lake Pontchartrain, thereby creating the Lower 9th Ward and New Orleans East. In 1943, the proposed project was initially presented to the U. S. Army Corps of Engineers by the Dock Board of New Orleans under the name "Alexander Seaway", in reference to Col. Lester F. Alexander, a member of the Dock Board who was one of the architects behind the New Orleans plan. A competing plan was also presented by Jefferson Parish, referred to as the "Arrow to the Americas,' also known as the Jefferson Seaway. In a matter of decades, the rapid growth of average ship size in the 20th century rendered the canal locks connecting the Industrial Canal to the Mississippi River obsolete; the MRGO as promoted in the 1950s was to help rectify this deficiency by permitting deep draft vessels to access the Industrial Canal inner harbor. Authorization for the MRGO was formally provided by the United States Congress in the Rivers and Harbors Act of 1956. Construction was completed in 1968. Due to rapid erosion of the surrounding marsh, the canal was already as much as four times wider by 2005 than as originally constructed. When MRGO was built, the channel was 650 feet (198 m) wide at the surface. By 2005 the channel had opened to up to 3,000 feet in some locations and had been dredged annually.

Levees along the MRGO and the Intracoastal Waterway were breached in approximately 20 places, directly flooding most of St. Bernard Parish and New Orleans East. Storm surge from the MRGO is also a leading suspect in the three breaches of floodwalls along the Industrial Canal. Three months before Katrina, Hassan Mashriqui, a storm surge expert at Louisiana State University's Hurricane Center, called MRGO a "critical and fundamental flaw" in the Corps' hurricane defenses, a "Trojan Horse" that could amplify storm surges 20 to 40 percent. Following the storm, an engineering investigation and computer modeling showed that the outlet intensified the initial surge by 20 percent, raised the height of the wall of water about three feet, and increased the velocity of the surge from to in the funnel shaped region between the converging MRGO and Gulf Intracoastal Waterway. Mashriqui believes this funnel effect contributed to the scouring that undermined the levees and floodwalls along the Gulf Outlet, the Intracoastal Waterway, and the Industrial Canal. "Without MRGO, the flooding would have been much less," he said. "The levees might have [been] overtopped, but they wouldn't have been washed away." The Army Corps of Engineers disputes this causality and maintains Katrina would have overwhelmed the levees with or without the contributing effect of MRGO since the storm surge was perpendicular to the length of the canal. Katrina's passage caused extensive shoaling of the MRGO, resulting in its impassability for deep draft oceangoing vessels. Officials of St. Bernard Parish immediately opposed its reopening. Maritime interests called for re opening the Gulf Outlet but equipping it with protective floodgates, or accelerating construction of the Inner Harbor Navigational Canal lock project, which when completed would allow MRGO to be closed without affecting deep draft commercial traffic.