Flash Flood Risk and the Paradox of Urban Development

AbstractThis paper traces the historic development of flood risk and the antecedent conditions that contributed to the catastrophic consequences in central South Carolina as the result of the 2015 flash flood. The study draws on archival and contextual research to underscore development paradoxes: the safe development paradox—federal policies aimed at making hazardous areas safer that have resulted in just the opposite—and the local government paradox—local governments permitting development of hazardous areas through lax land-use regulations and zoning while their residents bear the burden of hazards events. These paradoxes are used to illustrate the rapid development of an urban watershed and associated increase in flood risk. A chronology of development patterns from the 1930s with the expansion of the central core urbanized footprint of Columbia shows an increasing level of flood risk exposure as creeks were channelized, ornamental lakes developed, and high-end housing built, all with local government approval. In contrast, the uptake of National Flood Insurance policies remained below national averages for the level of risk in the region especially in the urbanized areas. Unabated hazard exposure and lack of mitigation set the stage for the significant losses incurred in the 2015 flood event and the uneven spatial variability in impacts. Unlike the impacts of Hurricane Katrina or the 2016 Louisiana flash floods, the burden of flood losses fell mostly on residents who could afford to bear the loss. With the exception of the discussion about buy-outs, this catastrophic flash flood event did not lead to a review of or change in land use, building, or zoning ordinances. Instead, the relatively quick residential recovery allowed the community to return to its predisaster state with seemingly few lessons learned.