Vulnerability of the U.S. Atlantic coast to hazards associated with extreme weather storms

DESCRIPTION: This project focuses on the vulnerability of the human and natural environment to cold-season extratropical cyclones (ETCs), in the Northeast U.S. coast, between the Delaware Bay and Rhode Island. We sought to provide data and tools to improve quantification of the risk, exposure and vulnerability posed to this region by extreme cold season weather for adaptation and preparedness purposes. Guided by this broad objective the project had the following specific objectives: (1) Determining the physical characteristics of the hazard posed to the Northeast U.S. by ETCs by analyzing their tracks, intensity, and movement, as well as the trend and modes of variability in these properties and their link to large-scale climate variability; (2) Building an empirical, statistical model of these systems to enable a robust probabilistic assessment of their occurrence in and impact on the study region; (3) Performing detailed calculations of the coastal flooding statistics associated with winter storm surge and wave action using state-of-the-art hydrodynamical coastal models forced with input from the historical re-analyses and from the synthetically generated meteorological forcing data; (4a) Analyzing available human system data to measure the vulnerability of the Northeast coast populations to flooding and other effects associated with ETCs; (4b) Analyzing remotely sensed (from space) ecological indicators of the coastal waters and assessing the feasibility of determining and monitoring the impact of extreme cold season ETCs on the Northeast coastal ecosystems; (5) Generating a statistical assessments of extreme events related to ETCs as measured (separately and jointly) by windspeed, precipitation rates, surge height, etc.

The ultimate goal of this project is to bring together results from all these tasks to address the objective of this project stated above. To achieve these goals, we assembled a team of investigators from Columbia University’s Earth Institute, NASA Goddard Institute for Space Studies, Stevens Institute of Technology and City College of New York, with additional support from Naval Research Laboratories. These investigators are grouped into task related teams that interact closely through regular monthly meetings in which they report progress and hold discussions on results, obstacles, and future work. In addition, team lead investigators alternate in making longer presentations of their work during these meeting. Continued interaction between teams is facilitated via a dedicated, shared web portal, where access of the entire group to posted presentations, reports, and other related documents, is enabled.

OUTCOMES: We performed detailed Norther Hemisphere ETC tracking based on several reanalyses of observations and compared between them to identify the more robust features of the track densities and the associated storm intensities.

Research on characterizing the movement (tracks) and pattern and on the associated impact of winter hazards for the U. S. Atlantic Coast has been performed. These papers identified the specific tracks of the hazard causing storm as well as the composite local features of the storm at the site of the impact. In the study of coastal flooding impact, we showed that while historically, tropical storms led to the largest inundation ETC’s don’t fall much behind in impact and in terms of risk posed to the coast they should be taken in serious consideration.
we contrasted various wintertime flood risk assessment products for NY/NJ Harbor, including historical observation-based assessments, FEMA’s 2014 assessment, and others, demonstrating a wide range (and epistemic uncertainty) in estimated flood risk. A follow up study examined the “compound” flooding from the combination of surge, tide, freshwater inputs (from rainfall), and sea level rise.

A stochastic model for ETC hazard over North America was developed as part of this project. The model is designed for generating a large number of synthetic ETCs whose statistical properties overall match those of historical ETCs. The synthetic storm set allows a robust estimation of the probability of local extreme-ETC, such that is not possible from historical data directly.

An analysis of societal vulnerability based on census data was performed. The study uses principal component analysis to build a Social Vulnerability Index (SoVI) at the census block-group level using U.S. census data from 1990, 2000 and 2010. The results indicate that the primary drivers of social vulnerability remained stable over this time period, with variables identifying deprivation firmly in the lead in the three years.

An analysis was performed of the economic impact, in terms of dollar value of property losses related to major ETCs that affected the study region. The analysis indicated that flooding (from all sources, strom surge, local rainfall, and rivers/streams inflow from remote locations) inflicts the costliest damages.