Vast Defenses Now Shielding New Orleans Jennifer Zdon for The New York Times Construction last month on the Seabrook floodgate complex in New Orleans. The overall defense system includes the biggest pumping station on the planet. NEW ORLEANS - Finally, there is a wall around this city. Nearly seven years after flood waters from Hurricane Katrina gushed over New Orleans, $14.5 billion worth of civil works designed to block such surges is now in place - a 133-mile chain of levees, flood walls, gates and pumps too vast to take in at once, except perhaps from space. Individual components of the system can be appreciated from a less celestial elevation. At the new Seabrook floodgate complex, climb up three steep ladders, open a trap door, and step out into the blazing sunlight atop a 54-foot tower that was not here just two years ago. From there one looks out over a $165 million barrier across the shipping canal that links Lake Pontchartrain, the Mississippi River and the Gulf Intracoastal Waterway. Two "lift gates," 50 feet across, can be lowered to block the waters of Lake Pontchartrain. A navigation gate 95 feet wide, whose curved sides weigh 220 tons apiece, can be swung gently but mightily into place. When open - which will be most of the time - the gates will allow easy boat traffic. When a storm threatens, however, they will seal off the canal from the kind of surge that devastated the Lower Ninth Ward in Katrina. Yet all that seems puny in comparison to the two-mile "Great Wall" that can seal off the channel from Lake Borgne to the east, or the billion-dollar west closure complex, which features the biggest pumping station on the planet. Now, hurricane season has returned, as it does each June. Whatever storms might approach New Orleans this year or in the future, they will encounter a vastly upgraded ring of protection. The question is whether it will be enough. When Katrina hit New Orleans in 2005, the city's hurricane protection system became a symbol of America's haphazard approach to critical infrastructure. The patchwork of walls and levees built over the course of 40 years was still far from complete when the storm came, and even the Army Corps of Engineers admitted that this was "a system in name only." Flood walls collapsed, and earthen levees built from sandy, dredged soils melted away. What has emerged since could come to symbolize the opposite: a vast civil works project that gives every appearance of strength and permanence. No other American city has anything like it. "This is the best system the greater New Orleans area has ever had," said Col. Edward R. Fleming, the commander of the New Orleans district of the corps. Marc Walraven, a district head in the Dutch ministry of transport, public works and water management, recently toured the defenses. While 100 percent safety is impossible, he said, and challenges in operations and maintenance can be expected as the corps passes the facilities over to local management in the coming year, "the constructions that have been built are in my opinion adequate to defend New Orleans." Tim Doody, the president of the levee board that oversees Orleans and St. Bernard Parishes, disagrees. While the construction appears to be strong, he said, the level of protection authorized by Congress for the corps to build is "woefully inadequate." The new system was designed and constructed to provide what is informally known as 100-year protection, which means it was built to prevent the kind of flooding that has a 1 percent chance of occurring in any given year. That standard is used by the Federal Emergency Management Agency to determine whether homeowners and businesses must buy flood insurance to qualify for federally regulated or insured mortgages. But New Orleans has seen storms far more damaging than the 100-year standard. Katrina is generally considered to have been a 400-year storm, and rising seas and more numerous hurricanes predicted in many climate-change models suggest harsher conditions to come.