Sea gates are another option that have proven very affective in other areas of the world such as Holland, Britain, and Venice, which is also below sea level and has a large number of canals. Sea gates are simply giant air-filled walls that cut off water flow. These gates would most likely be placed on Lake Pontchartrain’s two narrow outlets and would be only be closed if a storm was approaching. Such structures have been considered since the 1960’s, but the idea was crushed in the late 1970’s because people feared the gates would disrupt marine life and sediment transportation. However this should not be an issue since the gates are open the majority of the time. The main hurdle is cost, ranging from $500 million to 1 billion
Closing or covering certain canals is an option that would help prevent storm surges from reaching so far inland. Currently canals and channels can give storm surge direct access to inland neighborhoods. The Mississippi River Gulf Outlet [MRGO] is one of the canals that has caused major problems in the past. Where MRGO meets the Intracoastal Waterway there is a major area of funneling. The two fronts met at a narrowing point that forms the Industrial Canal and the water height is amplified 20-40%, putting intense pressure on floodwalls causing them to burst. After Hurricane Katrina hit the narrow strip of wetlands between MRGO and Lake Borgne got even smaller, bringing to reality the fear that the two waters might merge into one. MRGO has less than five ships navigating its channel per day; often times only one ship uses the outlet. MRGO has also amplified the wetland loss in the area, allowing salt water to intrude and kill off native vegetation. By keeping only heavily used channels open and turning the rest into trails or parks, flood damage could be reduced.
Adding a subterranean drainage system to the city is another idea that engineers have come up with. This would include