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Monday, Jan. 16, 2017



Research under way to determine future flooding

Despite statistics, most Shreveport/Bossier City residents give the Red River little thought, or did until 2015, when the muddy river grew from a sleepy little waterway into an inexorable force of nature.

Unusually heavy rains in Oklahoma and Texas swamped the river upstream, and when flood control structures were overtaxed, that water inevitably headed south toward Shreveport/Bossier City.

Three thousand, four hundred, forty feet above sea level where the states of New Mexico and Texas meet, the Red River begins. It crosses part of Texas, Oklahoma and Arkansas, then turns south and east across Louisiana before emptying into the Atchafalaya and Mississippi water system in West Feliciana Parish. Over those 1,360 miles, it collects water from over 65,000 square miles of land. The flow of that water, on average, is 57,000 cubic feet per second.

Greg Raimondo is chief of public affairs for the Vicksburg District of the United States Army Corps of Engineers. He said, “The flood control structures up there in the Tulsa District were overwhelmed with the amount of rain. Those dams got overwhelmed. I know Dennison at one point had a 2,000-footlong spillway that was being overtopped by about five feet.”

The flooding here prompted the Red River Valley Association to form a Flood Technical Committee, which examined the event to find ways to protect lives and property in the future. The report noted several issues of concern.

The Federal Emergency Management Agency’s flood level figures are no longer accurate because of changes to the river over time. Silt and sand fall out of the flowing river water all along its course, but they estimated that 1.6 million cubic yards, or about 2.29 million tons of wet sand, end up in the navigation channel at Pool 5 near Shreveport each year. In other words, the river is getting shallower.

In addition, the report found that “the height of the existing levee system in Caddo and Bossier parishes may not meet the three-foot free board (safety factor) established by FEMA, which may result in de-certification of the levee system.”

The group concluded the amount of dredging necessary along the river is not economically feasible or possible.

They estimated as many as 250,000 dump trucks of sand would need to be removed each year.

Caddo Parish Sheriff Steve Prator also serves as the area’s director of Homeland Security. In addition to his peace officer role, he is personally concerned about flooding. “Less flow of water on the Red is causing higher [flood] levels. In 1990, take my house, for instance; the water got up to the edge of the pool. Less water in 2015 put two feet of water in my house.”

The Corps has begun to study the river, according to Raimondo, “A hydrographic survey [was conducted of the river bottom] to figure out exactly what was happening with sediment, movement and issues like that. This look at the river will be combined with LIDAR [high-resolution 3D laser maps] so that we have a good idea about how the river looks in the bottom plus all the elevation, what’s in between the levees. Once we get that information all put together, we’ll turn our findings over to FEMA, and FEMA makes the determination of base flood elevation.” That’s the computed elevation to which floodwater is expected to rise.

The Corps has already constructed dikes and revetments along the river to help direct the flow, speeding it up to improve efficiency by preventing siltation and the formation of sandbars.

Riverfront development may also play a role in the problem, according to Prator. “The thing we have to do is quit building in places where water is supposed to be. It used to be that when you had too much water, you had a lot of room to spread out,” he said. Now there are “parkways, developments, concrete walls on both sides of the river. You have these dikes that were built by the Corps of Engineers to keep the water flowing into the lock and dam. What has happened is the trees have begun to grow on them. The trees have caught the sand. These are basically islands, so you don’t have the water storage.”

Raimondo added, “Areas that have been built up and asphalted now, or have houses with roofs, in areas that weren’t populated. [Now the water] comes off quicker. It comes off those roofs, it comes down those streets and those asphalt parking lots, it sheets off of those more than if it was just plain ground. That adds to the volume of water in the river.”

Prator’s goal is to make area citizens aware of the issues and to let them know what they need to do. Residents, he said, need to know where their property is in relation to the flood plain, and what and where the basic high water marks are.

“They need to determine if they need to take any steps towards building a levee around their house, their own preventative actions. They need to know they may need to move out again if they moved out the last time. They need to make sure they have flood insurance.”

The Corps of Engineers understands the local concern, but it can only report its findings to FEMA, who will ultimately make a recommendation. “Something’s changed, and we’re trying to figure out what has changed,” according to Raimondo. “You’ve got the same flows and higher stages.”

In the meantime, the responsibility remains on the individual to protect themselves and their property.

Prator put it this way: “I want people to know that government can’t save them.

Government can’t change this situation. You’ve got to make preparations on your own. It’s not a thousand-year flood and it’s not a hundred-year flood, it’s something that’s going to get worse and worse and worse. I’m not saying the sky is falling, but I want people to know the sky is lower.”

– Joe Todaro


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