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LEVEE BREACHES AND CLOSURE PROCEDURES
Research by Drs. M. Hanif Chaudhry and Ahmed
Kassem
Department of Civil and Environmental Engineering,
College of Engineering and Information Technology
In the wake of Hurricane Katrina,
flood-protection levees were breached, inundating most
of New Orleans. To mitigate the flood impacts, the U.S.
Army Corps of Engineers (USACE) worked around the clock
to close the breaches with sandbags. However, the
absence of systematic optimum procedures caused breach
closure plans set in the field to change repeatedly.
 For
example, the USACE requested a helicopter be brought in
to help them place 3,000-pound sandbags from the air.
But the size of sand bags had to be increased to 6,000
and 7,000 pounds because the lighter bags were washed
away. Later, the USACE built an access road to the site
and started dumping material from the side to close the
breach. These changes prolonged the time it took
officers to close the breach and resulted in substantial
delays to dewatering activities.
University of South Carolina researchers had three goals
in this project: (1) Test different closure methods and
investigate the best method of breach closure that is
economical and requires minimum time, (2) analyze the
hydraulics of the breach and obtain data on the flow
field and bed shear stress, and (3) prepare full
proposals for submission to the National Science
Foundation (NSF).
USC researchers built a 1:50 scale physical model based
on data provided by the USACE to simulate the closure of
the 17th Street Canal levee breach. While Hurricane
Katrina caused several levee breaches in New Orleans,
the worst of these breaches occurred on the 17th Street
Canal, with an overall length of 465 feet. The scale
model covered a 0.4-mile reach of the 17th Street Canal
and about 25 acres of flooded area downstream of the
breach using the cross-sections surveyed by the USACE
before the emergency closure of the breach. The model
was constructed of sealed plywood. The non-erodible
topography of the canal, breach, and the flooded area
were reproduced using a mixture of cement, sand, and
zonolite.
Based on the advances in cofferdam-closure techniques
for river diversion, researchers used the physical model
to investigate other possible closure methods with
potential for future applications. USC researchers also
investigated hydraulics of the breach. This included
determining the rating curve for the breach,
measurements of the flow field in the breach, and data
for the bottom shear stress downstream of the breach.
USC researchers tested different methods of closure that
have been used extensively on cofferdam projects,
including transverse dumping, toe dumping, a combination
of both transverse and toe dumping, and deflected
embankments upstream. Another method researchers tested
was using the buildings located downstream of the breach
to build a barrier. This project represents the first
step in developing procedures to prepare for future
breaches. One of the researchers’ main achievements in
this project was building a scale physical model. This
model will be used in the future for more comprehensive
studies on dike and levee breach applications in general
and for the 17th Street Canal breach in particular. The
findings of this research represent a base for future
systematic experiments, which can result in developing
optimum procedures for levee closure. In the long run,
this will improve the mitigation plans for levee
breaches. At the same time, the results will provide
answers to some questions relevant to the 17th Street
Canal breach that might concern both professionals and
the public.
 This
project has enabled USC researchers to initiate links
with state and federal agencies. This study integrates
the comprehensive work being conducted by the
Interagency Performance Evaluation Task Force (IPET) of
the USACE, which focuses on the performance of the
levees and the reasons of for their failure. This is
important because only limited systematic research is
available on the closure of a breached levee, and thus
trial and error procedures have been used in the past,
as was the case for the 17th Street Canal breach. As
compared to this, several procedures have been developed
for the closure of rivers by cofferdams for the
construction of dams, powerhouses, water intakes or
navigation locks.
USC researchers shared the findings of their research
with state and federal agencies. This project also
promoted training and learning through the participation
of one graduate and one undergraduate student in the
study. In addition, a middle school group and students
of an undergraduate honors class visited the USC
research laboratory to discuss the model. Using this as
a seed project, two proposals have been submitted to the
NSF for possible funding.Biographies
Dr. Hanif Chaudhry is known nationally and
internationally in the field of water resources with
specialization in the modeling of flows in open channels
and closed conduits. He is chairman and Mr. and Mrs.
Irwin B. Kahn Professor, Department of Civil and
Environmental Engineering, USC. Before that, he taught
at Washington State University, Pullman, Washington, and
Old Dominion University, Norfolk, Virginia. Dr. Chaudhry
received his MASc. and Ph.D. in Civil Engineering from
the University of British Columbia, Vancouver, Canada.
He has received several awards for teaching and
research, including Doctor Honoris Causa by the
Universidad Polytecnica Valencia, Spain, the Research
Achievement Award from the USC College of Engineering
and Information Technology. He has acted as a specialist
consultant on large water-resource projects at the
national and international level.
Dr. Ahmed A. Kassem is a research assistant professor in
the Department of Civil and Environmental Engineering,
USC. He received his Ph.D. degree from Washington State
University, Pullman, Washington, in 1996. Dr. Kassem has
more than 15 years of experience as an academician,
researcher, and consultant in the field of numerical
modeling of open-channel flows.
Research Team/Collaborators:
The research is conducted by Dr. Hanif Chaudhry and
Dr. Ahmed Kassem with the participation of Ahmed A.
Sattar, graduate student, and Michael Woolington,
undergraduate student. |
