Reverse Flow: The Role of Built Environments in Shaping Disaster.

In contrast to approaches that examine the impacts of human-built efforts to ameliorate calamitous natural events, this essay argues that a wide array of large structures shape the outcomes of these events. Further, significant human artifacts can succeed in their function vis-à-vis one set of natural events, but can have unanticipated, even reverse effects when natural forces exceed planned expectations. Risk assessments do not normally consider such side effects, suffering from an agnotological narrowing of focus. The historian's emphasis on temporal contextualization and contingency has important implications for policy and assessment of risk.