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Army Engineers Create Model To Better Understand Katrina

By John Schwartz


This is one enormous miniature. In a cavernous building here, workers are putting in 12-hour days to construct a scale model of a part of New Orleans at Lake Pontchartrain, at one-50th of its actual size.

The Army Corps of Engineers is building the 13,000-square-foot model to try to recreate the conditions that occurred in Hurricane Katrina and to help the agency figure out why things went so tragically wrong. The model is only one part of a $20 million effort to study the effects of the storm, along with computer simulations, intensive data gathering and analysis.

The work of what is known as the Interagency Performance Evaluation Task Force, which is focused here at the corps’ Engineer Research and Development Center, involves a byzantine system of checks and review, with hundreds of participants and dozens of organizations inside and outside of government.

In October, Secretary of Defense Donald H. Rumsfeld asked the American Society of Civil Engineers to form a panel to provide an external review of the data and analysis from the corps. The combined work will, in turn, be reviewed by a panel drawn together by the National Research Council.

The final report is not due to be released until June, but the process is already being attacked by critics as an expensive attempt to deflect blame from the corps.

It is expensive: The model alone will cost $325,000. Workers sculpt sand to precise heights and contours specified by a computer-aided design system. They cover the sand with a layer of concrete so smooth that it shines. When it is complete, it will represent the area around the south shore of Lake Pontchartrain, where the 17th Street Canal cut into the city. The canal inundated much of that well-to-do neighborhood, Lakeview.

The model is not an intricately detailed diorama with buildings, like the marvel at the New York 1939 World’s Fair. Workers will place plastic strips as rough representations of buildings. The coastline and canal, with its highway bridge running across it, are the important things. The workers will even reproduce the mass of debris that piled up along the bridge as the storm raged.

When it is complete, the corps will splash the shore with waves of precise height and frequency using a long machine that perturbs the water. They will observe how the water acts in the canal, and sensors will measure water height across the model.

A separate physical test will involve the centrifuge at Vicksburg, the most powerful in the world. Researchers will load a small mock-up of the canal and levee wall into the centrifuge to try to duplicate the forces of the water under pressure on the structure.

The investigators are also working with the National Oceanographic and Atmospheric Administration to get precise measurements of the storm as it made its way across the Gulf of Mexico, and computer-driven simulations are helping to determine how high the storm surge and wind-driven waves were, and what effect they might have had on the storm protection system.