Damage to residential buildings due to flooding of New Orleans after hurricane Katrina

This article analyzes the direct damage to residential buildings caused by the flooding of New Orleans after hurricane Katrina in the year 2005. A public dataset has been analyzed that contains information on the economic damage levels for approximately 95,000 residential buildings in the flooded area. The relationship between the flood characteristics and economic damage to residential buildings has been investigated. Results of hydrodynamic flood simulations have been used that give insight in water depths and flow velocities in the study area. In general, differences between the three polders in the observed distributions of damage estimates are related to differences in flood conditions. The highest damage percentages and structural damage mainly occurred in areas where higher flow velocities occurred, especially near the breaches in the Lower 9th Ward neighborhood. Further statistical analysis indicated that there is not any strong one-to-one relationship between the damage percentage and the water depth or the depth–velocity product. This suggests that there is considerable uncertainty associated with stage-damage functions, especially when they are applied to individual structures or smaller clusters of buildings. Based on the data, a more general approach has been proposed that could be used to distinguish different damage zones based on water depth and flow velocity for an area that is affected by flooding due to breaching of flood defenses. Further validation of existing damage models with the dataset and further inclusion of information on building type in the analysis of damage levels is recommended.