Comparing Inundation Maps Developed Using WHAFIS and STWAVE: A Case Study in Washington County, RI

Document Type

Conference Proceeding

Date of Original Version



In 2010, a report, Mapping the Zone, Improving Map Accuracy, was prepared by a FEMA flood map committee appointed by the National Academies' Water Sciences and Technology Board, which discussed theoretical and practical issues related to FEMA map accuracy. The present analysis presents a case study, which addresses in particular one of their major concerns: The use of a 1-D model to solve a 2-D problem. Finding #2 in the report stated: "Coastal flood maps can be improved significantly through use of coupled two-dimensional storm surge and wave models and improved process models, which would yield more accurate base flood elevations". The study re-computes the 100-year inundation maps in Washington County, using two-dimensional models. The initial and boundary conditions for wave simulations are based on results of fully coupled 2-D surge and wave models, the advanced circuulation model (ADCIRC) and the phase-averaged steady state spectral wave model (STWAVE), respectively, from the North Atlantic Coast Comprehensive Study (NACCS) performed by the U.S. Army Corps of Engineers. Waves are simulated using STWAVE over a series of high-resolution grids in nearshore and overland areas. Results are mapped and compared with FEMA's maps and transects.

Publication Title

Coastal Structures and Solutions to Coastal Disasters 2015: Resilient Coastal Communities - Proceedings of the Coastal Structures and Solutions to Coastal Disasters Joint Conference 2015