Stories tagged Atchafalaya Basin

May
12
2011

Mississippi River Levee in Baton Rouge, LA, taken May 11th 2011.: Panorama of the Mississippi River levee in Baton Rouge, LA near Louisiana State University, taken May 11th 2011.
Mississippi River Levee in Baton Rouge, LA, taken May 11th 2011.: Panorama of the Mississippi River levee in Baton Rouge, LA near Louisiana State University, taken May 11th 2011.Courtesy Azure Bevington
You might have heard about the terrible flooding that is occurring all along the Mighty Mississippi. As I write this I am sitting in Baton Rouge, Louisiana hoping the levees will hold. Normally the river in Baton Rouge is far below the tops of the levees. Flood stage, which is the water level at which the river would begin to flood surrounding areas without the levees acting as barriers, is 35 ft. Right now the water level is 42.8 ft and has risen 8 ft in just the last week. It is projected to crest at 47.5 ft and remain at that level for 8 to 10 days; this is higher than the previous record set in May 1927 of 47.28 ft. The tops of the levees that protect Baton Rouge are between 47 and 50 ft, they are currently sandbagging in areas less than 48 ft. Besides the possibility of overtopping there are also other problems that we need to look out for. When the river level remains high for an extended period of time the water can seep in and begin to saturate the soil, this can possibly weaken the levee structure. There is also the possibility of water going under the levee; this can result in sand boils, where the water bubbles up through the soil. It is very unlikely that this will happen, as the levees are strong and well constructed, but we need to be on the lookout for any problems.

Here in Baton Rouge we are much better off than many who live in communities within the Atchafalaya Basin, where the expected opening of the Morganza spillway could cause flooding of over 3 million acres (Click here to see a map of projected flooding in the basin) Many of these folks have already begun to sandbag their homes and to prepare to leave the area. The Morganza spillway is a large controlled gated structure that will divert water from the Mississippi River into the Atchafalaya Basin. The Atchafalaya Basin is a low lying cypress swamp that normally receives 30% of the flow of the Mississippi River through the Old River Control structure through the Atchafalaya River that winds its way through the swamp. This flood is projected to be larger than the 1973 flood and possibly even larger than the 1927 flood that devastated communities along the river, and brought about the passage of Flood Control Act of 1928. The magnitude of this year’s flood has already resulted in the opening of the Bonnet Carré spillway which diverts water into Lake Pontchartrain, this reduces the water levels as the River flows past New Orleans.

Stay tuned for updates on the flooding in Louisiana.

Have any of you been affected by the flood waters?