Numerical Modeling of Flow Through A Breached Levee and During Levee Closure Yafei Jia 1 , Tingting Zhu 2 , Cyrus K. Riahi-Nezhad 3 , and Yaoxin Zhang 4 ABSTRACT Excessive precipitation, fast snow melting, and storm surges due to hurricanes often result in levee breaching and inland flooding which devastates social facilities, residential properties, environment quality and threatens human lives. To enhance the resilience of society, it is important and necessary to study levee breaching flows and develop technologies for repairing damaged levees effectively during the flood. In this study, computational simulations were conducted using a finite element based two- dimensional and depth-integrated numerical model, CCHE2D. Data of a scaled levee breaching physical model were used to validate the computational model. The flood and levee breaching occurred during the Hurricane Katrina in New Orleans, LA, were studied in the Hydraulic Lab, and the measured flow distribution in the vicinity of the breached levee was simulated. The numerical model resulted in good agreement with the measured flow velocity and water surface elevation distribution. The computational model such validated was also applied to simulate the breach closure processes conducted in the physical model. This capability could help emergency managers and engineers to close breached levees more effectively. The practice of placing sand bags into the flow and closing the breaching was mimicked by using a graphic user interface. INTRODUCTION Catastrophic flooding is a major security concern of mankind. Failure of dams, levees and flood gates of water infrastructures such as reservoirs, lakes, rivers and coastal water will cause losses of many lives, billions of dollars in property damage and environment degradations. Historic records show that horrendous rains over inlands and storm surges in coastal zone due to hurricanes have resulted in failures of these structures and consequent devastating flooding. In addition, flooding could also occur should these structures be attacked by terrorists. Tools are therefore needed for flood analysis and control. Computational simulations can make comprehensive analysis on flooding and its impacts on the entire flooding area. In this paper, a computational model was applied to simulate the flow in the vicinity of a breached levee and the 1 Research Professor, National Center for Computational Hydroscience and Engineering, the University of Mississippi, 102 Carrier Hall, University, MS 38677, USA, Phone: (662) 915-7783, Fax: (662) 915-7796, E- Mail:jia@ncche.olemiss.edu 2 Research Scientist, National Center for Computational Hydroscience and Engineering, the University of Mississippi, 102 Carrier Hall, University, MS 38677, USA, Phone: (662) 915-3960, Fax: (662) 915-7796, E-Mail: tzhu@ncche.olemiss.edu 3 Ph. D. candidate, Department of Civil and Environmental Engineering, University of South Carolina, 300 main Street, Columbia, SC 29208, USA, Phone: (803) 777-2618, Fax: (803) 777-0670, E-Mail: RIAHINEZ@engr.sc.edu 4 Research Scientist, National Center for Computational Hydroscience and Engineering, the University of Mississippi, 102 Carrier Hall, University, MS 38677, USA, Phone: (662) 915-3960, Fax: (662) 915-7796, E-Mail: yzhang@ncche.olemiss.edu