More than a million residents have had to deal with power outages and threats of flooding as Ida hit the Gulf states on Monday with heavy rains and high winds.
One death has been reported and Louisiana Governor John Bel Edwards has said he expects the death toll to rise.
Ida was the first real test of New Orleans’ new flood control measures known as the Hurricane and Storm Risk Reduction System. It is a network of dikes, gates, pumps and flood walls designed to protect the area from a “once-in-a-century” storm.
Heavy rains have caused flooding on the streets, but the levees around New Orleans, rebuilt after the floods from Hurricane Katrina in 2005, appear to be working, although a few failures have been reported south of the city.
Electricity was another matter, as all of New Orleans and three parishes were declared without electricity. The winds cut eight Entergy power lines and toppled a transmission tower in the Mississippi River.
Entergy officials did not say when power would be restored. Search and rescue efforts began Monday.
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Hurricane Ida was a Category 4 hurricane that landed in Port Fourchon, Louisiana at 11:55 am Sunday, with sustained winds of 150 mph and barometric pressure of 930. The associated winds and rain expanded over 400 miles of the Gulf Coast from Louisiana to Florida.
It was the most powerful hurricane to hit Louisiana since the beginning of modern record keeping. Its winds are linked to estimates of a hurricane that hit Last Island in August 1856, based on historical reconstructions made by researchers at the National Oceanic and Atmospheric Administration using logbooks and other documents.
Ida dropped up to 20 inches of rain in parishes along the west side of Lake Pontchartrain and caused flash floods throughout the area.
Although most of New Orleans’ dikes – many of which were installed or upgraded as part of a $ 14.5 billion post-Katrina project – appeared to be intact, other dikes have either failed or were swamped along some rivers and bayous south of the city, threatening hundreds of homes.
Flash floods were reported after a levee rupture near a Phillips 66 refinery in Alliance, Louisiana, about 20 miles south of New Orleans, the Associated Press reported. Plaquemines Parish, fearing 11-foot storm surges, asked 6,800 residents to evacuate on Friday as Ida approached.
Dikes are simple but essential works to control flooding. The word levée comes from the French term the sink, meaning to get up or get up.
Dikes are walls or embankments built along the banks of rivers or bodies of water to prevent water from entering protected areas when the level rises. They are usually constructed of clay or non-porous soil and are wider at the bottom, narrower at the top. They can be reinforced with rock or grass.
New Orleans is protected by two sets of dikes and dikes: one for the Mississippi River and the other for Lake Pontchartrain. Their size is based on topography, the Wall Street Journal reported. Some are 30 feet tall, others 12 to 15 feet tall.
The project included improved and better protected pumps to extract water from New Orleans. The city depends on the pumps because it is surrounded by dikes and is largely below sea level.
The project is one of the largest civil engineering programs in US history. Its construction took more than 10 years and was completed in May 2018.
The US Army Corps of Engineers reported in April 2019 that system protection could start to deteriorate as early as 2023 without improvement. The report cited sea level rise and accelerated erosion of barrier islands in southern Louisiana.
The Corps recommended a 50-year plan to increase the heights of levees along the Mississippi River and elsewhere, at an estimated cost of $ 3.2 billion.
THE SOURCE USA TODAY Network Reports and Research; The Associated Press; US Army Corps of Engineers; inventionandtech.com