The Governor of the State of South Carolina points out to reporters in every press conference that the floods are a one-in-1000 year event. In other words, the devastation from these floods is not our fault, this is an extremely improbable event and there is no way we could have been prepared for it.
The cost of the flood is estimated at USD 1 billion and rising.
Suppose someone offered you a lottery ticket with a USD 1 billion payout and told you that only 1,000 tickets were being sold, how much would you be willing to pay for that ticket?
Is there a problem with the way we present our water data to the public and decision-makers?
People are easily fooled by statistics and they are also desensitized to reporting of threats from the environment. Recent research Newell et al. (2015) concludes that the assumption that “summaries of the nature and scale of disasters will lead people to reduce their exposure to risk” is false. In other words, disaster reporting actually increases the appeal of a disaster prone region. This paradox may partly be explained by a conclusion that after a disaster the region will be safe for the next 1,000 years.
What is our responsibility for this absurd conclusion?
For starters, what is the provenance of the one-in 1,000 frequency estimate? How was the uncertainty of that estimate communicated to end-users and decision-makers? What are the assumptions implicit in this frequency analysis and what is the validity of those assumptions in the current climate and landscape? What is the role of cascading dam failures in the severity of flooding? National geographic proposes 4 hidden causes of dam failures that are relevant to this case. In other words, what are the preventive investments that could have dramatically reduced the cost of payout in this lottery?
People are not very good at understanding concepts like probability, uncertainty, and risk.
What can we do differently to help them understand, as they re-build in the floodplain, that it is nearly certain they will be devastated again, we are only uncertain about exactly how soon?
If we want to refine the estimate of how soon, we should invest more in relevant and reliable water data. Please comment below.
Photo credit: Photo by Ryan Johnson | Flooding in North Charleston | The aftermath of the flooding in North Charleston, South Carolina caused by over 15 inches of rainfall resulting from Hurricane Joaquin. | Taken on October 4, 2015 | License
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