Harvey Could Become Costliest Ever US Natural Disaster

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Measured by loss of life, the Galveston hurricane of 1900 was the worst ever in U.S. history, killing between 8,000 and 12,000 people. Property damage totaled around $30 million.

Hurricane Katrina killed nearly 2,000 people when it struck New Orleans and neighboring areas in 2005. Property damage totaled $100 billion, according to FEMA.

While no one expects loss of life anywhere near the Galveston total, the current count of 30 dead is expected to rise. Meteorologists at Accuweather estimate that the impact of Hurricane Harvey on the U.S. economy will approach $160 billion, or about 0.08% of U.S. GDP of $19 trillion.

Joel N. Myers, founder, president, and chairman of Accuweather, said:

The disaster is just beginning in certain areas. Parts of Houston, the United States’ fourth largest city will be uninhabitable for weeks and possibly months due to water damage, mold, disease-ridden water and all that will follow this 1,000-year flood.

When meteorologists refer to floods as “x-year” events, they are using a shorthand for probability percentages. For example, a 1,000-year flood means there is a 0.1% chance that such a flood may occur in any given year. Likewise, there is a 1% chance that a 100-year flood will occur in any year and a 0.5% chance that a 500-year flood will strike. While statistically unlikely, the chances are not zero of having a 100-year or 1,000-year flood in the same place in two or more consecutive years.

In April of last year, Houston and the surrounding area were hit by heavy rainfall that cost seven people their lives and more than 1,000 property owners their homes. Risk analysts at CoreLogic have created a presentation that shows how the flooding extended beyond the Special Flood Hazard Area (SPHA), typically the 100-year floodplain, into the moderate-risk (500-year) floodplain.

CoreLogic analysts also calculated that 52% of properties (1.21 million) in the Houston-Sugar Land-Baytown metro area are located outside the SPHA and are at high or moderate risk of storm damage from Harvey.