Using New LiDAR to Update Old Tsunami Hazard Maps on the Island of Hawaii

Tsunamis pose a considerable risk to life and property along the shorelines of the Hawaiian Islands. To help mitigate this risk, the federal emergency management agency (FEMA) has included tsunami runup mapping on coastal flood hazard maps in the County of Hawaii. In 2007, the U.S. Army Corps of Engineers (USACE) collected high-resolution airborne bathymetric and topographic LiDAR data along the Hawaiian Island coasts. Recently, FEMA funded a study to update the tsunami runup mapping for the City of Hilo, which was previously completed with topographic data collected in the late 1970s. Because the tsunami analysis is dependent on topographic characteristics, a re-delineation of the existing runup elevations onto the new terrain data would not be accurate. This paper includes a description of the updated tsunami runup analysis, a comparison between the old and new results, and details on some of the unique challenges that arose from incorporating high resolution data and results into existing coastal flood hazard maps.