
Research & Development
LEAP-HI: Compounding Risk and Mitigation Options for Building Infrastructure Experiencing Coastal Flooding-Related Saltwater Deterioration and Seismic Hazard
Flood Inundation Risk of Buildings Using the Coastal Modeling System in Hilo, Hawaii
By: Amy Kimura
May 14, 2025
M.S. in Civil Engineering Plan B and Business Administration, University of Hawaii at Manoa, May 2025, under Oceana Francis
Additional contributor(s): Linqiang Yang
This study assesses the vulnerability of the coastal community of Hilo, Hawai‘i, USA, to flood inundation under different future sea level change (SLC) conditions projected by the National Oceanic and Atmospheric Administration (NOAA). Two sets of scenarios are considered: one based solely on projected SLC, and the other integrating SLC with historical hurricane events, i.e., Hurricane Madeline and Hurricane Lester. For the SLC-only scenarios, inundation extents were derived using a bathtub method, comparing ground elevation with Mean Higher High Water surfaces adjusted for projected SLC. For the hurricane-integrated scenarios, inundation areas were simulated using the Coastal Modeling System (CMS-Wave and CMS-Flow) developed by the U.S. Army Corps of Engineers (USACE). The coupled CMS model was validated using water level data from the tide gauge station and wave data from the National Data Buoy Center buoy. For both sets of scenarios, the number of impacted buildings was estimated by overlaying inundation areas with building footprints identified using Microsoft Open Building Data. Fragility curves were developed for each set of scenarios using a cumulative normal distribution approach to estimate the probability of building inundation under varying SLC values. Results highlight Hilo’s significant vulnerability to compound flooding events, emphasizing the need for coastal adaptation planning. Future work should include progressive damage analysis and cross-validation with alternative coastal models to refine flood risk projections. For more information see https://compoundinghazards.wixsite.com/resiliency.
Hurricane Madeline and Hurricane Lester on August 29, 2016 moving west towards Hilo (NASA, 2016)
Flooding in Hilo, HI, USA caused by Hurricane Lane in 2018 (Hawaii Emergency Management Agency, 2023). As of 2023, HIEMA estimates hurricane storm surge impacts on the Island of Hawaii: Population: 1,092 persons and Buildings: Replacement cost value of $58B.
Inundation extents under MHHW-based sea level change (SLC) scenarios of 0.11m, 1.11m, 2.11m, and 3.11m
Inundation extents under Hurricane-based sea level change (SLC) scenarios of 0.11m, 1.11m, 2.11m, and 3.11m