A flooded power plant at Oswego, Kansas, on the Neosho River on April 23, 1927 (National Oceanic and Atmospheric Administration)
As the Mississippi River continues to rise Monday, threatening Memphis and other cities on its shores, we take a look back at another deluge: The Mississippi River flood of 1927, which is still the landmark event against which many U.S. floods are measured, and one that forever changed how levees and flood control systems are built across the country.
According to John M. Barry, a New Orleans resident and the author of the New York Times bestseller “The Great Flood of 1927 and How it Changed American History,” between six and 11 inches of rain fell along the entire Mississippi River in 1927. Some places received 14 inches of rain in 18 hours, and the river was running at three million cubic feet per second. Currently, the flow rate prediction just downriver from Cairo, Illinois is for 1.89 million cubic feet per second — about half that of the 1927 flood.
“The most subtle but most important impact of (the 1927) flood is that it changed the way Americans viewed the federal government and redefined the way people viewed government and individual responsibility,” Barry said during a lecture at FEMA’s recent National Flood Conference in New Orleans.
Barry talked to The Rundown about how the massive flooding in the Mississippi River Valley now compares to the situation in 1927, and how public preparedness for flood disasters has changed since Hurricane Katrina.
What comparisons do you see between the flood of 1927 and the flooding currently taking place along the Mississippi River?
First, let’s hope they’re not comparable. The 1927 flood destroyed the homes of almost one percent of the entire population of the United States. At its widest point, the Mississippi River was pretty close to 100 miles across and you had a true inland sea. So, the river has the capacity of spreading that wide. Today, if we had a major levee breach along the Mississippi, it would be just like in 1927. Obviously, I hope that doesn’t happen, and I don’t think that will happen.
Arkansas City, Arkansas on April 27, 1927 (NOAA)
The Bird’s Point floodway that was just dynamited was a result of the 1927 flood, it’s part of the way [the Corps of Engineers] realized they need to allow rivers room to spread out [after the flood]. Obviously water has two ways of filling volume, it can either rise high or spread out. So creating this floodway, essentially close to doubling the area of the river, lowers the flood height. Downstream over the next few weeks, there are [other] floodways that may be opened.
There is a spillway in New Orleans that may also be opened. The difference between a floodway and a spillway is that a spillway is actually going straight to the ocean, [in this case] through Lake Pontchartrain, about 15 miles above New Orleans. There is another floodway that runs through central Louisiana to take water out of the Mississippi River that may be opened, that’s only been opened once before in 1973.
It’s a serious situation, there’s no question about it. And people certainly don’t realize the consequences of a levee break on the lower Mississippi River. And that would be a flood that would spread from the river until you get to high ground, which in many cases is 40 or 50 miles from the river.
Aside from opening levees and trying to get rid of some of the water in the river, what other options are available to the Corps of Engineers?
That’s it. There are flood control reservoirs on the tributary systems to delay the passage of water into the river and those are being employed. So number one, you try to keep water out of the river through those reservoirs, and number two, you try to give the river an escape hatch to alleviate some of the pressure against the levees, and that’s all you can do. And, inspect those levees constantly.
The levees along the lower part of the Mississippi River are built to a much higher standard than any other levees in the U.S. because of the 1927 flood when the country said, we will never allow this to happen again. And, in those days, they didn’t define the standards of a levee the way we do now but they’re roughly levees that would hold a once-in-a 750-year flood. However, when you try to figure out how big a flood like that is, you really can’t because you only have a couple hundred years of data. So, how can you really project how big a 750-year, 500-year or 1000-year flood is? You really don’t know. But they are the strongest levees in the U.S. And if they break, then you’ve got real problems.
A levee breach during the 1927 flood at Mounds Landing, Mississippi (NOAA)
If a flood on the magnitude of the 1927 flood were to strike again, what has changed or not changed since Hurricane Katrina, the most recent major flood event, in terms of preparation?
Number one, we will have a protection system that will do what it’s designed to do. In Katrina, it really was a man-made disaster because flood walls in most of the city were designed to hold the storm. New Orleans actually only got sideswiped, it did not bear the direct full force of Katrina, and what hit us on the backside was not a great storm. Those flood walls were just badly designed. They were supposed to hold that flood. So the system that’s about to be finished as hurricane season hits this year, it will work as designed. It’s well-built and well-designed. I sit on the local levee board that oversees most of metropolitan New Orleans, and we are confident in the system. The problem is that it’s only a 100-year protection standard (for flood insurance). That sounds good, but it’s actually a low standard, really the lowest in the developed world. In Japan and Holland, they protect against an ocean storm to a 10,000 year standard. So, it is not great protection but it’s a lot better than we had.
Do you think that the public has changed its view of flood preparedness since Katrina, and are any lessons learned at risk of regressing?
I don’t think it’s at risk of regressing, I think it’s regressed. Even in New Orleans, it’s amazing to me how many people have forgotten and dismissed the risk and seem to have other priorities that are directly in conflict with flood protection. In terms of raising houses and other ways of building in a safe way — in Holland they call it “living with water” — I’m extremely disappointed in what’s been going on. Part of that is because the state [of Louisiana], which has a program for that, has not done a very good job getting money to people who wanted to do it. That’s a major disappointment.
To change what’s going on in flood protection in this country, resilience is number one. Number two is to change the standard of 100-year protection, and number three is to do some comprehensive planning.