Infrastructure built to protect cities from flooding can increase economic damages elsewhere, according to a study. As sea levels rise, coastal cities are increasingly investing in levees and seawalls to mitigate flooding. While protective structures can reduce flood damage locally, they can exacerbate flooding along other parts of the shoreline to an extent that has not been sufficiently quantified. Michelle Hummel and colleagues used a 2D depth-averaged hydrodynamic model of San Francisco Bay to simulate tidal circulations and shoreline interactions under four possible sea-level rise scenarios for 30 different shoreline modification scenarios in which only one stretch of shoreline is protected by construction of a new seawall. The authors integrated maximum water depths extracted from the models with topographical and building stock data to estimate the local reductions and regional increases in economic damage and flooding associated with each scenario. The results varied with local geography and development density. However, under one scenario, the net increase in flooding across the bay was 36 million cubic meters, and another scenario resulted in external damages totaling $723 million. The authors suggest that protective coastal structures may need to be planned at regional levels, spanning multiple jurisdictions, to account for such hydrodynamic interactions. According to the authors, the analysis could be extended to other densely populated estuaries.
Article #20-25961 "Economic evaluation of sea-level rise adaptation strongly influenced by hydrodynamic feedbacks," by Michelle A. Hummel, Robert Griffin, Katie K. Arkema, and Anne D. Guerry.
MEDIA CONTACT: Michelle A. Hummel, The University of Texas at Arlington, Arlington, TX; tel: 330-605-0761; email: email@example.com
Proceedings of the National Academy of Sciences