SGER: Understanding the mechanics of particle motion in levee-breach closure

University South Carolina Research Foundation, Columbia SC

Investigators

Abstract

Understanding the mechanics of particle motion in levee breach closure M. Hanif Chaudhry and Ahmed Kassem ABSTRACT Several levees were breached following hurricane Katrina, inundating most of the city of New Orleans. Attempts to close the most critical levee breach on the 17th Street Canal using sandbags as large as 10,000 pounds and transported by helicopters were unsuccessful. Due to limited available information on breach closure, trial-and-error procedures have to be utilized which result in taking long times for closure and extensive flooding. As compared to this, considerable laboratory and field investigations for the closures of cofferdam have been conducted for river diversion to build dams and several concepts developed in these studies could be extended to levee closure. The cofferdam studies were based on visual observations of the motion of the dumped material which can be improved utilizing presently available advanced digital particle tracking velocimetry (DPTV) techniques that allow reliable and accurate measurements of the particle movements which are critical for the understanding the mechanics of the process. For example, preliminary tests on a 1:50 scale physical model of the 17th Street Canal breach built recently in our hydraulic laboratory utilizing internal funds show that a slight change in the positioning of a sandbag to close the breach dramatically affects its movement. In the proposed research, we will explore the applicability of DPTV techniques for the understanding of the mechanics of particle motion, to extend the cofferdam closure methods for the closure of levee breach and to develop new methodologies for determining the optimum particle size. The expected results include the development of an algorithm for the DPTV to visualize the motion of the dumped material and understanding the mechanics of particle motion for determining the minimum size of the material for levee closure. The findings of this research represent a base for future research on developing systematic optimum procedures for the closure of levee breaches. Although the causes of the recent levee failure in New Orleans are being investigated at a number of institutions, to the best of our knowledge, no investigations are in progress for an equally important task for the breach closure. The objective of this study is to initiate preliminary research so that the time and costs of breach closure and flooding are minimized. The proposed research is exploratory in nature as it represents "preliminary work on untested ideas". Different DPTV techniques are available in the literature and have been used in several other applications. These techniques have not been used to visualize the motion of the dumped material and the evolution of breach closure. These preliminary data are needed to prepare a full proposal for a comprehensive study for levee closure. The broader impacts of the study include the participation of one graduate and two undergraduate students, especially from the under-represented groups. In addition, as these studies progress, information will be exchanged with the Catholic University, Belgium and Swiss Federal Institute of Technology, Switzerland, where extensive investigations have been conducted on dam and dyke breaches as well as peer-reviewed journal publications for the universal dissemination of results.