Friday, May 6, 2011


From a recent news article:

"Compared to the Great Mississippi Flood of 1927 this flood is going to be a lot nastier," said Marty Pope, senior hydrologist for the National Weather Service in Jackson, Miss.

The river is predicted to crest at 64.5 feet on May 17 in the Vicksburg, Miss. area. Vicksburg has a flood stage of 48 feet, which means the river will crest more than 16 feet above normal, according to flood experts at the National Weather Service.

The flood waters will reach more than a foot above the Yazoo Backwater Levee near Yazoo City, Miss. and this will flood thousands of acres of farmland, said Pope.

There were major floods on the Mississippi in 1927, 1937, 1973, 1993 and 2008. The 1927 flood caused up to 1,000 deaths and left 600,000 homeless. Floodways were adopted as a response.

Camillo said it was too early to estimate expected damage from the 2011 flooding. He noted that much has changed since the 1927 flood, including the structure of the levees and the addition of dozens of reservoirs throughout the Mississippi River basin and floodways.

The Mississippi has four floodways: Birds Point and three spillways in Louisiana.

"There is a very good possibility that we would operate three floodways ... and we have never done that before," Camillo said."

Camillo is the Chief Historian of the Mississippi River Commission.

What do I mean when I indicate that flood-ways are political decisions not hydrologic decisions. Fluid dynamics underpin hydrology and are complex but nothing could be as labyrithian as the politics of flood-ways their designation and enforcement. Witness recent court decisions on the USACOE decision to blow the Bird's Point Levee in several places.

Why? WELL to grossly over simplify designation of a floodway is where the high velocity waters during flood stage will go. By increasing channel efficiency in several ways the water will seek the path of least resistance. Thus, if on one side of the river a flood wall is constructed the river will flow over the town on the other side without the flood wall. Or perhaps a community chooses to improve hydraulic efficiency by mowing down forest and paving over the main channel thus improving channel efficiency and speeding the water downstream. The problem of course is that the Mississippi and its levee system is not a system at all an various political decisions over time have left USACOE holding the bag. Well this time they really will be holding it. Perhaps opening the MORGANZA spillway and opening the Old River Control Structure sending waters to where the Mississippi river would like to head naturally. And save NOLA of course but goodbye Morgan City and others.

Well the die are cast and now only the passage of the next few weeks will see how this plays out.

Whatever the situation Old Man River will keep on rolling along!