New Orleans and Hurricane Katrina. I: Introduction, Overview, and the East Flank

Abstract

The failure of the New Orleans regional flood protection systems, and the resultant catastrophic flooding of much of New Orleans during Hurricane Katrina, represents the most costly failure of an engineered system in U.S. history. This paper presents an overview of the principal events that unfolded during this catastrophic hurricane, and then a more detailed look at the early stages of the event as the storm first drove onshore and then began to pass to the east of the main populated areas. The emphasis in this paper is on geotechnical lessons and it also includes broader lessons with regard to the design, implementation, operation, and maintenance of major flood protection systems. This paper focuses principally on the early stages of this disaster, including the initial inundation of Plaquemines Parish along the lower reaches of the Mississippi River as Katrina made landfall, and the subsequent additional early levee breaches and erosion along the eastern flanks of the regional flood protection systems fronting Lake Borgne that resulted in the flooding of the two large protected basins of New Orleans East and St. Bernard Parish. Significant lessons learned include ͑1͒ the need for realistic assessment of risk exposure as an element of flood protection policy; ͑2͒ the importance of considering erodibility of embankment and foundation soils in levee design and construction; ͑3͒ the importance of considering all potential failure modes; and ͑4͒ the problems inherent in the construction of major regional systems over extended periods of multiple decades. These are important lessons, as they are applicable to other regional flood protection systems in other areas of the United States, and throughout much of the world.

Geohazards and large, geographically distributed systems

“…Hurricane Katrina caused enormous damage in the New Orleans area, resulting in the greatest natural disaster loss in US history, as well as controversy about the performance and failure mechanisms of the regional hurricane protection system (e.g. ASCE Hurricane Katrina External Review Panel, 2007;Christian, 2007;Seed et al, 2008a).…”

A holistic model for coastal flooding using system diagrams and the Source-Pathway-Receptor (SPR) concept

“…Hurricane Katrina in 2005 in New Orleans, USA is one of the costliest coastal flood disasters in history (Seed et al, 2008). Though bigger than expected and prepared for, the event provided several key lessons for flood risk management.…”

“…Due to the size and complexity of the New Orleans coastal defence system as well as the relevant organisations, there was a lack of overview on the state of flood defences prior to the event. This led to weaknesses and maintenance gaps in some dyke sections being overlooked that aggravated flooding in the region (Seed et al, 2008). A similar lack of overview on emergency response measures and flood defences led to aggravation of damage during the July 2007 floods in England (Pitt, 2008) and Storm Xynthia in France in 2010 (Kolen, 2010).…”

“…However, widespread damage still occurs repeatedly despite excellent forecasts and numerical models being available. Events such as Storm Xynthia in France (Kolen, 2010), the July 2007 floods in the UK (Pitt, 2008) and Hurricane Katrina in the US (Seed et al, 2008), though well-forecasted and modelled, caused considerable damage in their respective regions, and revealed shortcomings in our understanding of coastal flood systems. These shortcomings have more to do with the application of numerical and quantitative models than with the models themselves.…”

Levee reliability analyses for various flood return periods – a case study in southern Taiwan

“…(Dou et al, 2014) During Hurricane Katrina, the levee system surrounding New Orleans experienced catastrophic overflowing, which was possibly due to shoaling and resulted in the inundation of approximately 80 % of the city. Many researchers have studied the stability of levees under overflowing (Seed et al, 2008a, b;Xu et al, 2012). The consequence of overflowing for the flood wall in suburban areas of New Orleans, USA, was the gap formed between the flood wall and the canal-side backfill.…”