Nine Fallacies of Floods

A number of important misconceptions or fallacies stand in the way of a better understanding of the nation’s flood problem. The fallacies are not universal, with many flood experts, decision makers, and sectors of the public escaping their seductive logic. But enough people do fall prey to these fallacies of floods so as to create obstacles to improved utilization of the lessons of experience. This paper uses three of these lessons to organize presentation of the nine fallacies: • We know the wrong things about the nature of the problem. Fallacy 1: Flood frequencies are well understood. Fallacy 2: Damaging flooding in recent years is unprecedented because of ‘global warming’. Fallacy 3: Levees ‘prevent’ damages. Fallacy 4: Flood forecasts are universally available. • We don’t know enough about why and with what intensity we should act. Fallacy 5: Societal vulnerability to floods is well understood. Fallacy 6: Data on flood casualties is a proxy for flood risk. Fallacy 7: Data on flood damages is a proxy for flood risk. • We know enough about what might be done. Fallacy 8: Knowledge leads to action. Fallacy 9: The U.S. flood problem can be addressed without Federal leadership and support. The purpose of raising the fallacies in this paper is to contribute to a systematic definition of the nation’s flood problem.