A new study published in the Journal of Geophysical Research: Oceans has revealed that the common practice of building dams in coastal estuaries to prevent flooding may actually contribute to more intense coastal flood events. The surge in popularity of these massive infrastructure projects globally is in response to intensifying storms, salt intrusion, and sea-level rise caused by climate change. By analyzing data from Charleston Harbor, South Carolina, dating back over a century, researchers found that coastal dams do not necessarily mitigate flooding. Depending on the duration of a surge event and friction from the flow of water, dams can either increase or decrease flood risks.
Lead author Steven Dykstra, an assistant professor at the University of Alaska Fairbanks College of Fisheries and Ocean Sciences, explained that estuaries are shaped like funnels, narrowing as they extend inland. Introducing a dam can shorten the estuary with an artificial wall that reflects storm surge waves moving inland. The narrowing channel shape also causes small reflections that change with the surge duration, similar to waves splashing in a bathtub. In the case study of Charleston Harbor, researchers used computer modeling to assess flood responses in 23 other estuaries in various geographic areas, both dammed and naturally occurring. The models confirmed that the basin shape and modifications that shorten it with a dam are crucial in determining how storm surges and tides move inward.
The study also revealed that areas located far from coastal dams could still be directly affected by human-created infrastructure. In the Charleston region, the highest storm surges occurred more than 50 miles inland, emphasizing that sea-level rise is making inland areas increasingly susceptible to coastal effects. Dykstra highlighted the importance of understanding that even those living far inland are not immune to coastal influences and the potential for massive flooding events. With the continuous threat of climate change exacerbating flooding risks, it is crucial for communities to be aware of the potential impacts of coastal infrastructure on flooding patterns and preparedness.
The researchers involved in the study, including Enrica Viparelli, Alexander Yankovsky, and Raymond Torres from the University of South Carolina, as well as Stefan Talke from California Polytechnic State University, San Luis Obispo, collaborated to assess the impact of dams on coastal flooding events. By combining data analysis, measurements, and computer modeling, the study provided valuable insights into how dams in estuaries could either increase or decrease flood risks depending on various factors. Understanding the complex interactions between infrastructure, natural environments, and climate change is essential in developing effective strategies to mitigate the impacts of coastal flooding and improve resilience in coastal communities.
The findings from this study underscore the importance of considering the unintended consequences of building dams in coastal estuaries and the need for a more comprehensive approach to flood risk management. It is essential for policymakers, urban planners, and coastal communities to prioritize sustainable solutions that take into account the potential impacts of human interventions on natural systems. By incorporating the insights gained from this research into coastal planning and infrastructure development, communities can better prepare for and adapt to the challenges posed by increasing flood risks associated with climate change and sea-level rise. Ultimately, a holistic and integrated approach to flood risk management is necessary to build resilience and mitigate the impacts of coastal flooding events in a changing climate.
