The flooding was exacerbated by specific hazards related to building a city in a delta, wetland environment. Poor governance on local, state and national levels also intensified the hazards. However the flooding did focus the nations attention on the factors and inequity that lead to the increased vulnerability of certain segments of the New Orleans population. The evacuation of the City was the largest evacuation seen in the US since the Civil War (ASCE, 2007). To say the impacts to the residents of New Orleans were massive would be an understatement. There were 1,200 deaths caused by the drowning, exposure while waiting for rescue or medical treatment and death from waterborne infections and pathogens. Thousands of homes were destroyed or no longer inhabitable. Damages to residential, industrial, public and commercial buildings, universities and hospitals reached approximately $21 billion (ASCE, 2007). Infrastructure losses to canals, roads, bridges, utilities and telecommunications reached $6.7 billion (ASCE, 2007). Infrastructure loses were so bad the job base, economic generation, and people have not returned.
There have been hundreds of thousands of residents dislocated. Many people living on government assistance were sent to live in other cities spread out across the country. Others with the means to return simply chose not to live in a location that is so ripe for storms. New Orleans population is roughly half of what it was prior to the storm. When discussing hazard drivers to the City one must look at the location of New Orleans (City). The location makes it exceptionally susceptible to flooding. The City is surrounded by water, in the Mississippi delta on the east and west banks of the Mississippi, south of Lake Pontchartrain. The majority of New Orleans, about 80 percent, is at or below sea level (Travis, 2005). In fact the highest point in New Orleans is 6 feet above sea level. For eons the Mississippi river has been depositing trillions of tons of sediment into the Gulf of Mexico. This sediment tends to be soft soils called Marsh, clays, silt and sand. As a result of being on built on this sediment New Orleans is going through a rapid rate of subsidence, a settling of the ground surface.
This natural process occurs due to chemical reactions in the organic Marsh soils. This process in nature is usually balanced out by the sediment deposits from the Mississippi river. However, groundwater pumping, petroleum extraction and flood control measures are adversely interfering with the replenishment rate and increasing the subsidence (ASCE, 2007). An environmental hazard specific to New Orleans is that a majority of the surrounding wetlands have been drained and developed. Wetland removal increases the hazard due to the fact that wetlands act as a buffer zone and absorb some of the hurricanes energy (Travis, 2005). Efforts to restore wetlands are under way but they have not had the large scale funding required to make them effective (Travis, 2005). Another hazard borne by New Orleans is bad governance. The risk from flooding was never truly appreciated prior to Katrina. Due to its physical location New Orleans has always been under threat of hurricane damage; therefore, hurricane protection systems (HPS) have been constructed over the years.
However in true New Orleans governance style the HPS had been constructed in a piecemeal fashion. Prior to Katrina the project had been expected to be completed in 2015 (ASCE, 2007). The primary HPS is the levee system. The United States Army Corps of Engineers (USACE) is the entity that designs, and the majority of the Mississippi River levees. In 1946 congress authorized a major campaign to tackle hurricane related flooding. As New Orleans has grown, the US government has authorized more projects aimed at hurricane protection. However government mismanagement and design flaws rendered these systems useless in Katrina. The USACE levees are primarily of earthen design with concrete set on top (Travis, 2005). Levees are wide at the base and become narrow towards the top like a pyramid with its top flattened. Unfortunately, new residential development in New Orleans has been pushed along the edges of levees, so as design standards called for larger levees, the space was not available to expand the bases. Therefore, flood walls were placed on top of the levees.
The floodwalls are generally concrete and reinforced with steel or I-beams. The floodwalls come in I-shape and T-shape. I-shaped floodwalls are installed deep into the ground and protrude straight up and tend to be generally weaker than the T-shaped floodwalls that are actually an inverted T with the base buried in the levee (ASCE, 2007). There are 350 miles of levees and floodwalls in the New Orleans region with 284 miles under federal responsibility. 169 miles of the federal levees were damaged in Katrina (ASCE, 2007). The levees were overtopped and breached. Some were not adequately reinforced and were scoured away be the rushing floodwaters. Some had gaping breaches over 450 feet and numerous I-shaped floodwalls were cracking all over the city. According to the American Society of Civil Engineers (2007), the levee safety factors were too low and the soil strength of the material in the levees was overestimated. These errors compounded and lead to the collapse of the levees (ASCE, 2007). Additionally the dynamic pressure from development was also a hazard driver.
Development was too close to the levee areas and hindered adequate expansion of the existing levees. Another level of the hurricane protection is provided by the numerous pumping stations in and around the City. There are many sections of New Orleans that are below sea level, therefore there are numerous pumping stations in operation throughout the city. The pumping stations are designed to handle large rainfalls but they are not designed to handle the amount that could be generated in a hurricane event. The flooding from Katrina overwhelmed the pumping stations and resulted in the stations going offline. However, the pumping stations might not have done much to alleviate the flooding. The pumping stations are designed to send the water they pump into the canals, the same canals that breached the levees and were responsible for some of the flooding.
Hurricane Katrina had major implications for many demographic segments of New Orleans; however, people with limited means were impacted very hard. New Orleans traditionally has one of the highest unemployment rates in the US at 38 percent. The timing of Katrina at the end of the month of August meant many on government assistance were on the last of their payments till September. Many people in this area did not have the means to leave the City and had to ride out the storm. Ironically, many of the local government and state evacuation plans relied on individuals finding their own way out of the city despite the fact that many people in New Orleans do not own cars. Consequently, the people left in the city during the storm were many of its most vulnerable, people without strong livelihoods, strong levels of health and unable to protect themselves; basically the poor, the elderly and the sick. Blaikie/Wisners pressure and release framework fits this flooding event very well. The root causes of limited access to safe structures, limited access to the economic system are present.
The dynamic pressures of bad governance, bad HPS design and implementation along with macro-force pressures of rapid population growth and wetland loss are present. The unsafe conditions of lack of high ground, low income levels, special risk groups and inadequate preparedness are also present (Wisner, et al, 2004). When Katrinas floodwaters arrive on the scene it presents a horrible situation with devastating effects. Pelling deconstructs vulnerability into three distinct areas which are shaped by economic and social pressures (Pelling, 2004). The first area is exposure to risk which includes the location and the set of specific environmental risks. The second area is resistance to risk which includes health and livelihood strength. The third area is resilience, which includes coping and adaption strategies and also preparedness. In the case of New Orleans, the exposure aspect is apparent. The City is surrounded by water and below the sea level in numerous locations. The environmental risks of subsidence and wetland degradation serve to compound the exposure risks.
Resistance to risk is low due to the high level of unemployment in New Orleans. Resilience is very low as evidenced by the evacuation plans that rely on residents to have private vehicles, inadequate HPS and bad governance response to the event. Both the dynamic pressure release model and Pellings model of vulnerability do an effective job at deconstructing the Katrina event. However, the dynamic pressure release model is more suitable to describing Katrina events due to the fact that it applies a greater weighting to the impact of bad governance to the disaster situation. In numerous cases it took days for help to reach the survivors. The federal agency ultimately responsible for disaster mitigation, preparedness, response and recovery planning is the Federal Emergency Management Agency (FEMA).
FEMA was consistently abysmal in all aspects of mitigation, preparedness, response and recovery. Days before the storm they down played the possible scenarios and in consultation with Mayor Ray Nagin they made the call to evacuate far too late. They did not mobilize the correct amount of resources to the area prior to, or even after the flooding. FEMA emergency trailer homes were so full of toxic paints and plastics that FEMA was found liable in court and had to replace hundreds of thousands of trailers. As a result of all the errors FEMA has been restructured and former FEMA executives have been fired. The dynamic pressure release model is weaker then the Pelling model in the area of resilience analysis. The same level of emphasis is not placed on resilience in the dynamic pressure release model. The coping and adaptation strategies are not given the same level of focus by the dynamic pressure release model. Levees and floodwalls are being rebuilt to stronger standards.
Homes are being rebuilt, development is being pushed further back from levees and floodwalls and plans to restore wetlands are being revaluated. However, the main coping strategy being employed by many of the former residents and businesses is relocation. The population is half of pre Katrina levels and the employers have not returned to New Orleans. A combination of the two approaches would be best for understanding this disaster event. Both are good at analysis of the root causes and environmental factors that are part of an event. The dynamic pressure release could be used to gain a stronger understanding of the build up and the actual event. The model of vulnerability could be used to focus on the recovery effort. They say that hindsight is twenty-twenty perfect vision, but one did not need perfect vision to see Katrina coming.
All the location and environmental factors were present for a catastrophic storm event. In fact many simulations had been run and continuously determined a high level of destruction from a Category 3 storm. In spite of all the evidence to the contrary, the government still had a lack of preparedness and an attitude of indifference which lead to the destruction of one of Americas cultural treasures. It is disappointing that Katrina had to occur to make people aware that adequate disaster preparation begins with strengthening social protections. The disaster has lead to positive changes in disaster preparedness and an acknowledgement that effective mitigation plans must take into consideration the differing vulnerabilities of the population.
American Society of Civil Engineers (ASCE) (2007) The New Orleans Hurricane Protection System : What went Wrong and why : A report / by the American Society of Civil Engineers Hurricane Katrina External Review Panel, on-line at http://www.asce.org/files/pdf/ERPreport.pdf website last updated 2007, accessed 21 March 2009. National Hurricane Center (NHC) (2005), Tropical Cyclone Report: Hurricane Katrina 23-30 August 2005, on-line at http://www.nhc.noaa.gov/pdf/TCR-AL122005_Katrina.pdf, website last updated 2006-8-10, accessed 22 March 2009. Pelling, M., 2003. Social Vulnerability in the City, The Vulnerability of Cities: Natural disasters and social resilience. Easthscan. Pp 46-67 Travis, J., 2005. Hurricane Katrina: Scientists Fears Come True as Hurricane Floods New Orleans, Science 309: 1656-1659. Wisner, B., Blaikie, P., Canon, T. and David, I., 2004. The Challenge of Disaster and Out Approach, At Risk: Natural Hazards, Peoples Vulnerability and Disasters. Routledge. Pp 2-48. Wisner, B., Blaikie, P., Canon, T. and David, I., 2004. The Disaster Pressure and Release Model, At Risk: Natural Hazards, Peoples Vulnerability and Disasters. Routledge. Pp 49-86