Plaquemines spillways for lowering water levels in New Orleans
Marcel van de Waart is taking a PhD in Civil Engineering at the University of Twente. As part of his thesis he worked for Royal Haskoning in New Orleans, using a computer model which predicts the water levels around New Orleans and Plaquemines Parish during hurricanes. Three years ago Hurricane Katrina caused floods with catastrophic results. Consultants from Royal Haskoning are advising New Orleans about sustainable solutions in the battle against floods. When all of the data from Marcel’s model calculations have been processed his findings will be submitted to the U.S. Army Corps of Engineers.
Plaquemines lies to the south of New Orleans. It is a sparsely populated but fertile strip of land, around a hundred kilometres long and three kilometres wide alongside the Mississippi. During Katrina it became evident that the levees around Plaquemines and New Orleans actually had an undesirable effect. During the hurricane the water built up against the levees and had nowhere to go and as a result the levees collapsed. Eighty percent of the city was flooded and more than 1575 people lost their lives.
Spillways
‘Raising all the levees in that area would be extremely expensive, and would only cause more water to build up. So at the moment I’m investigating the effects of spillways and the best places to put them,’ explains Marcel. ‘These are sites where sections of the levees along the Mississippi could be deliberately lowered or removed. This would mean that in an emergency, the water could be drained off in a controlled manner in places where it can do less damage so that the water build-up would not be so great. Not all the calculations have been finished yet, but everything indicates that with this method a reduction in the water level of half a metre to a metre can be achieved for the east side of New Orleans.’
Effect of high river discharge
‘What I’m going to investigate now,’ continues Marcel van de Waart, ‘is the effect of the combination of a high water level in the Mississippi and a hurricane, something that has not so far received much attention in the current high water calculations. A huge part of the US is situated in the Mississippi basin and a lot of rain in the basin creates a high water level in the river. Previously people had always assumed that a high water level and the occurrence of a hurricane did not coincide. That was in fact the case three years ago with Hurricane Katrina, but the floods along the Mississippi immediately before the hurricane season earlier this year have raised more and more doubts about that.’
Supercomputer
Marcel is now halfway through his research. In America he has concentrated on computer technology and a study of the area. In the calculation of the ADCIRC model he was allowed to make use of Notre Dame University’s supercomputer in South Bend. Royal Haskoning is collaborating with the university on projects around New Orleans. ‘That’s where I was initiated into working with the ADCIRC calculation model that I use for my research. Together with two other students I was allowed to give a presentation about our projects to the Army Corps. Here in the Netherlands I’m going to continue my calculations with the data I’ve amassed and work out my conclusions, so that project manager Mathijs van Ledden can submit my report.’
Contact: Mathijs van Ledden
+31 (0)6 52 36 19 87
m.vanledden@royalhaskoning.com
