Search

Search Results

• 1. [Article] A Validated Tropical-Extratropical Flood Hazard Assessment for New York Harbor

  Recent studies of flood risk at New York Harbor (NYH) have shown disparate results for the 100 year storm tide, providing an uncertain foundation for the flood mitigation response after Hurricane Sandy. ...

  Citation × Citation Citation Abstract Copy Title: A Validated Tropical-Extratropical Flood Hazard Assessment for New York Harbor Author: Orton, Philip M., Hall, T. M., Talke, Stefan A., Blumberg, Alan F., Georgas, Nickitas, Vinogradov, S. Year: 2016 Recent studies of flood risk at New York Harbor (NYH) have shown disparate results for the 100 year storm tide, providing an uncertain foundation for the flood mitigation response after Hurricane Sandy. Here we present a flood hazard assessment that improves confidence in our understanding of the region's present-day potential for flooding, by separately including the contribution of tropical cyclones (TCs) and extratropical cyclones (ETCs), and validating our modeling study at multiple stages against historical observations. The TC assessment is based on a climatology of 606 synthetic storms developed from a statistical-stochastic model of North Atlantic TCs. The ETC assessment is based on simulations of historical storms with many random tide scenarios. Synthetic TC landfall rates and the final TC and ETC flood exceedance curves are all shown to be consistent with curves computed using historical data, within 95% confidence ranges. Combining the ETC and TC results together, the 100 year return period storm tide at NYH is 2.70 m (2.51–2.92 at 95% confidence), and Hurricane Sandy's storm tide of 3.38 m was a 260 year (170–420) storm tide. Deeper analyses of historical flood reports from estimated Category-3 hurricanes in 1788 and 1821 lead to new estimates and reduced uncertainties for their floods and show that Sandy's storm tide was the largest at NYH back to at least 1700. The flood exceedance curves for ETCs and TCs have sharply different slopes due to their differing meteorology and frequency, warranting separate treatment in hazard assessments. Title: A Validated Tropical-Extratropical Flood Hazard Assessment for New York Harbor Author: Orton, Philip M., Hall, T. M., Talke, Stefan A., Blumberg, Alan F., Georgas, Nickitas, Vinogradov, S. Year: 2016 Recent studies of flood risk at New York Harbor (NYH) have shown disparate results for the 100 year storm tide, providing an uncertain foundation for the flood mitigation response after Hurricane Sandy. Here we present a flood hazard assessment that improves confidence in our understanding of the region's present-day potential for flooding, by separately including the contribution of tropical cyclones (TCs) and extratropical cyclones (ETCs), and validating our modeling study at multiple stages against historical observations. The TC assessment is based on a climatology of 606 synthetic storms developed from a statistical-stochastic model of North Atlantic TCs. The ETC assessment is based on simulations of historical storms with many random tide scenarios. Synthetic TC landfall rates and the final TC and ETC flood exceedance curves are all shown to be consistent with curves computed using historical data, within 95% confidence ranges. Combining the ETC and TC results together, the 100 year return period storm tide at NYH is 2.70 m (2.51–2.92 at 95% confidence), and Hurricane Sandy's storm tide of 3.38 m was a 260 year (170–420) storm tide. Deeper analyses of historical flood reports from estimated Category-3 hurricanes in 1788 and 1821 lead to new estimates and reduced uncertainties for their floods and show that Sandy's storm tide was the largest at NYH back to at least 1700. The flood exceedance curves for ETCs and TCs have sharply different slopes due to their differing meteorology and frequency, warranting separate treatment in hazard assessments. Close

• 2. [Article] Channel Shallowing as Mitigation of Coastal Flooding

  Here, we demonstrate that reductions in the depth of inlets or estuary channels can be used to reduce or prevent coastal flooding. A validated hydrodynamic model of Jamaica Bay, New York City (NYC), is ...

  Citation × Citation Citation Abstract Copy Title: Channel Shallowing as Mitigation of Coastal Flooding Author: Orton, Philip M., Talke, Stefan A., Jay, David A., Yin, Larry, Blumberg, Alan F., Georgas, Nickitas, Zhao, Haihong, Roberts, Hugh J., MacManus, Kytt Year: 2015 Here, we demonstrate that reductions in the depth of inlets or estuary channels can be used to reduce or prevent coastal flooding. A validated hydrodynamic model of Jamaica Bay, New York City (NYC), is used to test nature-based adaptation measures in ameliorating flooding for NYC’s two largest historical coastal flood events. In addition to control runs with modern bathymetry, three altered landscape scenarios are tested: (1) increasing the area of wetlands to their 1879 footprint and bathymetry, but leaving deep shipping channels unaltered; (2) shallowing all areas deeper than 2 m in the bay to be 2 m below Mean Low Water; (3) shallowing only the narrowest part of the inlet to the bay. These three scenarios are deliberately extreme and designed to evaluate the leverage each approach exerts on water levels. They result in peak water level reductions of 0.3%, 15%, and 6.8% for Hurricane Sandy, and 2.4%, 46% and 30% for the Category-3 hurricane of 1821, respectively (bay-wide averages). These results suggest that shallowing can provide greater flood protection than wetland restoration, and it is particularly effective at reducing "fast-pulse" storm surges that rise and fall quickly over several hours, like that of the 1821 storm. Nonetheless, the goal of flood mitigation must be weighed against economic, navigation, and ecological needs, and practical concerns such as the availability of sediment. Title: Channel Shallowing as Mitigation of Coastal Flooding Author: Orton, Philip M., Talke, Stefan A., Jay, David A., Yin, Larry, Blumberg, Alan F., Georgas, Nickitas, Zhao, Haihong, Roberts, Hugh J., MacManus, Kytt Year: 2015 Here, we demonstrate that reductions in the depth of inlets or estuary channels can be used to reduce or prevent coastal flooding. A validated hydrodynamic model of Jamaica Bay, New York City (NYC), is used to test nature-based adaptation measures in ameliorating flooding for NYC’s two largest historical coastal flood events. In addition to control runs with modern bathymetry, three altered landscape scenarios are tested: (1) increasing the area of wetlands to their 1879 footprint and bathymetry, but leaving deep shipping channels unaltered; (2) shallowing all areas deeper than 2 m in the bay to be 2 m below Mean Low Water; (3) shallowing only the narrowest part of the inlet to the bay. These three scenarios are deliberately extreme and designed to evaluate the leverage each approach exerts on water levels. They result in peak water level reductions of 0.3%, 15%, and 6.8% for Hurricane Sandy, and 2.4%, 46% and 30% for the Category-3 hurricane of 1821, respectively (bay-wide averages). These results suggest that shallowing can provide greater flood protection than wetland restoration, and it is particularly effective at reducing "fast-pulse" storm surges that rise and fall quickly over several hours, like that of the 1821 storm. Nonetheless, the goal of flood mitigation must be weighed against economic, navigation, and ecological needs, and practical concerns such as the availability of sediment. Close