Communities and Areas at Intensive Risk in the Mid-Atlantic Region: A Reanalysis of 2011 Hurricane Irene with Future Sea Level Rise and Land Subsidence

Powerful tropical cyclones along the U.S. Eastern Seaboard produce several unique coastal hazards that result from the combination of heavy inland rainfall and storm surge that accompany events ranging from strong Nor'easters to tropical storms and major hurricanes. Combined with longer-term challenges of rising sea levels attributed to coastal subsidence and steric expansion, impacts from these events are expected to increase, especially in the lower Chesapeake Bay in Portsmouth and Norfolk, VA. In 2017, NASA's Earth Science Disasters Program hosted a regional workshop to explore these issues with particular focus on coastal Virginia and North Carolina, given impacts that NASA's Langley Research Center and the community of Hampton Roads had experienced from several past events. The workshop brought together partners from academia including: Virginia Institute of Marine Science, Old Dominion University, Hampton University, George Mason University, and the University of Alabama. These universities partnered with emergency management and scientists from NASA among other partnering federal agencies to explore capabilities among the team that could improve understanding of the physical processes related to these hazards, their potential impact to these changing communities, and identify methodologies for supporting emergency response and risk mitigation. A pilot demonstration research initiative was developed to examine coastal hazards in two communities adjacent to the James River and Elizabeth River: Portsmouth, VA, and Norfolk, VA. The demonstration study examined inundation via these approaches: 1) reanalysis of impacts from 2011 Hurricane Irene, using numerical weather modeling in combination with coastal surge and hydrodynamic, urban inundation modeling to evaluate combined impact scenarios considering sea level rise, 2) remote sensing of flood extent from available optical and synthetic aperture radar useful for identifying storm impacts and as precursors for future response efforts, 3) adding value to remotely sensed flood maps through depth predictions and related efforts, and 4) examining coastal subsidence as measured through time-series analysis of synthetic aperture radar observations. This presentation will highlight outcomes of the demonstration's activities and describe a series of combined storm surge and sea level rise scenarios relative to the lower Chesapeake Bay during 2011 Hurricane Irene and the anticipated impacts of a similar strength storm in 2045.