Copyright 2006 The Times-Picayune Publishing Company
By EZRA BOYD, Lousiana State University Hurricane Center, Baton Rouge, La.
Times-Picayune (New Orleans)
As the LSU scientist whose task it was to estimate the number of flood fatalities resulting from Hurricane Katrina, I would like to explain the rationale that led us to the conclusion that Katrina’s death toll could reach 10,000 and the reason that I believe it did not.
The flood fatality rate is defined as the number of fatalities divided by the exposed population and is a crucial variable in flood fatality calculations. During Hurricane Betsy, approximately 35,000 residents of Orleans Parish were exposed to the storm surge flooding resulting in approximately 50 deaths. For Betsy, a flood that reached depths of 6 to 8 feet, the flood fatally rate equaled 0.001. However, Hurricane Katrina resulted in flood depths of 13 to 15 feet.
The flood fatality rate depends heavily on the flood water depth. For past storm surge floods characterized by water depths of 13 to 15 feet the fatality rate is around one-third. With an estimated 100,000 people exposed to floods in the region, a fatality rate of 0.33 would result in approximately 33,000 fatalities.
A more comprehensive calculation produced the estimate of 10,000 to 20,000 potential fatalities. This calculation, however, does not account for the effectiveness of search and rescue operations. Indeed, this important factor distinguishes Katrina’s flood from most other major floods.
It’s clear that local first responders led a search and rescue operation of unprecedented magnitude after Katrina. This effort resulted in a significantly lower death toll than what could have occurred.