Spring :: Summer 06: What happened with Katrina?

Two Katrina team members explore the key levee breach in New Orleans’ devastated 9th Ward: Les Harder from the California Department of Water Resources (left) and Tom Zimmie, Rensselaer professor and acting chair of civil and environmental engineering.

The question has vexed everyone since the first levee gave way. Now some of Rensselaer’s leading researchers are seeking answers.

With powerful centrifuges and systems dynamics software, teams are using exceptional tools to explore critical issues from the levee failures to the FEMA response. Their investigations not only place Rensselaer among the leaders in Katrina research, but may well inform public policy for years to come.

On the ground in New Orleans

When the nation’s leading experts in natural disasters headed to New Orleans, Tom Zimmie naturally took his place among them. The experience landed him an audience with two congressional committees.

For a week, beginning each morning at 8 a.m., the researchers set out in the dark to examine the New Orleans levees from every angle. As part of the NSF-sponsored reconnaissance team, Zimmie, professor of civil and environmental engineering, and the other experts who are collaborating with the U.S. Army Corps of Engineers and the American Society of Civil Engineers investigated the damage caused by overtopping, the effectiveness of emergency “patches,” and the decision process behind the levee configuration. According to the team’s testimony before the U.S. Senate Committee on Environment and Public Works, the levees might have failed for all those reasons and then some.

Tom Zimmie

“Field observations indicated various causes: overtopping of the levees, erosion, failure in foundation soils underlying the levees, seepage through the soils under the levees causing piping failures, and this is not a complete list,” Zimmie told the committee in a prepared statement.

The initial report, released to the Senate Committee on Homeland Security and Governmental Affairs in November, suggested that many breaches occurred at “weak links” where different levee or wall sections came together. But pinpointing causes will require more data, so the Corps turned to Rensselaer again—for a smaller solution.

The view from the whirled

Tarek Abdoun '94

The levee model, a steel plate surrounded by soil, whirled around at 90 mph. When the water infused into the model reached just one inch from the top, the plate started to tilt, the soil began its slide—and the team at Rensselaer’s Geotechnical Centrifuge Center knew they had something.

Led by Tarek Abdoun, associate professor of civil and environmental engineering, the researchers carefully constructed the model to simulate—precisely—the levee structure of the 17th Street Canal amid the conditions of Hurricane Katrina. In doing so, they used Rensselaer’s 150 g-ton centrifuge, one of only four in the United States, which enables researchers to test gigantic structures under extreme conditions, using scale models.

The experiment itself, which took eight to 10 days to build and run, required extreme care in every phase. “It took two months for us to finalize the design,” Abdoun said. “Then, as soon as you start testing the model, you can’t stop in the middle—and you must maintain the soil at the proper moisture, or else your readings will not reflect actual field conditions.”

The 150 g-ton centrifuge at Rensselaer’s Geotechnical Centrifuge Research Center was used by researchers to carefully construct a model to simulate—precisely—the levee structure of the 17th Street Canal amid the conditions of Hurricane Katrina.

The failure of the model led to the team’s preliminary findings: that the 17th Street levee may have slid on a layer of weak clay just beneath the peat that underlies the earthen structure. Abdoun presented the findings to peer review groups from the American Society of Civil Engineering and the National Academy of Sciences.

Whatever the research eventually finds, the implications reach far beyond New Orleans. “We have thousands of miles of levees in the United States,” Zimmie noted, “and every state has some levees. This work benefits the entire country.”

What happened to FEMA

William "Al" Wallace '61

While millions celebrated the holidays in December, three Rensselaer students—including a Ph.D. student from New Orleans—were talking to Katrina victims, collecting all the perishable data they could find. Their findings may go a long way toward shaping federal emergency response.

The head of the research team—William “Al” Wallace, professor of decision sciences and engineering systems at Rensselaer—had deployed the students as part of a National Science Foundation Small Grant for Exploratory Research (SGER) to study the FEMA and Coast Guard responses to Katrina.

Under the grant, the team is developing a dynamic model of organizational processes that sheds light on the effect of recent changes in federal emergency management. Wallace believes the preliminary findings will point to two factors: power and culture. “We will undoubtedly show that as budgets and rulemaking authority diminish, the power of an organization to act in an emergency diminishes,” he said. “When FEMA lost Cabinet-level position, it lost that power.”

As for culture, “what professionals do in the emergency response field is to create a culture,” noted Wallace. “Look at fire and police departments; the culture they have built over decades allows them to respond effectively in emergencies. When FEMA was subsumed into the Department of Homeland Security, the culture was broken up.”

Wallace is participating in the research with Bryan Jones and Peter May, co-principal investigators at the University of Washington.

When everyone rushes to help

Jose Holguin-Veras

When thousands of donations converge from hundreds of agencies on one site, it can actually prevent necessary supplies from getting to the people who need them most. José Holguín-Veras aims to do something about that.

With funding from NSF’s Human and Social Dynamics/Small Grant for Exploratory Research program, Holguín-Veras is in charge of a research team that traveled to New Orleans to collect data and conduct interviews surrounding the logistics of critical supplies to the affected area.

The professor of civil and environmental engineering is studying a field long overlooked by engineers: convergence. “After an extreme event, there is a massive flow of information, goods, and people to the event site,” he explained. “The substantial amount of non-priority donations can clog the supply chains of critical supplies.”

Far from discouraging donations, Holguín-Veras is trying to streamline the logistics behind convergence. In his current study, the project team is using advanced mathematical formulations to describe the logistic process, developing short-term forecasting tools to assess the future needs of critical supplies, and creating mechanisms to control the flows of non-critical supplies. Team members include professors Satish Ukkusuri (Rensselaer) and Tricia Wachtendorf (University of Delaware’s Disaster Research Center) as well as Noel Pérez (a Ph.D. student at Rensselaer).

Social scientists have studied convergence in some detail, which explains the unusual blend of experts from both fields in this project. “We are marrying state-of-the-art social science research with state-of-the-art transportation modeling,” Holguín-Veras said. “This is something that nobody else has tried to do.”

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