COASTAL FLOODING & SOLUTIONS, Workshop Case Studies
Evolution of Storm Surge Inundation under Relative Sea Level Rise and its Impact on Transportation Infrastructure
Hampton Roads, Virginia
Old Dominion University, Assistant Professor
Relative sea level rise is increasing the vulnerability of coastal infrastructure to storm surge flooding. We have develop a hydrodynamic+wave model and applied it to simulate storm surge inundation under different local sea level projections to quantitatively assess some of these vulnerabilities. Our study area is located in southeast Virginia where the rate of relative sea level rise is the highest in the U.S. East Coast. The model is first validated with documented water levels in water and over land during Hurricane Irene (2011). It is then applied to investigate changes in vulnerability of transportation infrastructure to relative sea level rise by quantifying changes in flood intensity and duration over access roads to critical bridges which are identified based on elevation and traffic volume. Furthermore, the length of flooded roadways as well as the extent and volume of inundation is quantified under different combinations of relative sea level rise and storm return periods. With a 1.8 m sea level rise, an upper bound of sea level projections in the study area in 2070, collective flood intensity and duration increase by factors of 23 and 51, respectively and the length of flooded roadways increase by a factor of 9 and 7 from their present values for 10 and 50-yr storms, respectively. Variations in flood intensity, duration, area, and volume under storm/sea level rise combinations indicate that storm surge response to relative sea level rise is generally nonlinear, and linear superposition of storm surge and sea level rise mostly overestimates inundation intensity while consistently overestimates inundation volume. Variation of rate of change in total inundation volume is more complex and shows that the linear summation overestimates flood volume for small to moderate rates of sea level rise while it underpredicts it for high sea level projections. This suggests that nonlinear effects act to intensify flood vulnerability at an accelerated rate as sea level rises.
Development of understanding how vulnerability of local critical spots in transportation infrastructure to storm surge changes with sea level rise, demonstrating importance of dynamic storm surge modeling vs bathtub modeling
compound flooding, social sciences