Abstract
Flood Insurance Rate Maps (FIRMs) are developed by the Federal Emergency Management Agency (FEMA) to provide guidance in establishing the risk to structures and infrastructure in the coastal zone from storm surge and coincidental waves. The maps are used by state agencies and municipalities to help guide coastal planning and establish the minimum elevation standard for new or substantially improved structures. A summary of the methods used and results of 2012 FIRM mapping are presented for Charlestown, RI; a coastal community located along the exposed, southern shoreline of the state. Concerns with the methods used in the 2012 analysis are put in context with the National Research Council’s (NRC) 2009 review of the FEMA coastal mapping program. New mapping is then performed using state of the art, fully coupled surge and wave modeling and data analysis methods to address the concerns in the NRC review. The new maps and methodologies are in compliance with FEMA regulations and guidelines. The approach makes extensive use of the numerical modeling results from the recent US Army Corp of Engineers (USACE), North Atlantic Coast Comprehensive Study (NACCS 2015). Revised flood maps are presented and compared with the 2012 FIRM map to provide insight into the differences. The new maps highlight the importance of developing better estimates of offshore surge dynamics and its coupling to waves, dune erosion based on local observations, and the advancement in nearshore mapping of waves in flood inundated areas by the use of state of the art, two-dimensional wave transformation models.
Highlights
Federal Emergency Management Agency (FEMA) leads the national effort for the development of Flood Insurance Rate Maps (FIRMS) for coastal flooding for the purposes of establishing the risk structures and infrastructure face from inundation and wave attack and setting the associated insurance rates
To assess the performance of the North Atlantic Coast Comprehensive Study (NACCS) model predictions for the study area, the model predicted water levels vs. return period were compared with data from the closest National Oceanic and Atmospheric Administration (NOAA) National Ocean Survey (NOS) water level station at Newport, RI (Station ID #8452660) [18]
The water levels vs. return period for the mean value for NACCS surge only and the NOAA mean are in very good agreement
Summary
Federal Emergency Management Agency (FEMA) leads the national effort for the development of Flood Insurance Rate Maps (FIRMS) for coastal flooding for the purposes of establishing the risk structures and infrastructure face from inundation and wave attack and setting the associated insurance rates. The contractor used FEMA’s Coastal Hazard Analysis and Modeling Program (CHAMP)/Wave Height Analysis for Flood Insurance Studies (WHAFIS) [4] to estimate the waves in the flood inundated areas. This program computes the wave crest elevations along representative transects using a 1-D wave action equation. The 100 year Still Water Elevation Level data (SWEL), empirically determined wave setup, and the wave height estimates are assembled to provide estimates of the Base Flood Elevation (BFE) (Figure 2). To20r1e1prLeasseenr tImthaegitnogp,oDgertaepcthioyna, nanddbRaathnygminget(rLyIDinAtRh)edflatoaoDdiegditaalreEale,vthateiownaMvoedaenl a(DlyEsMis)ufsoerdRIth[1e62] 011 Laser Imaging, Detection, and Ranging (LIDAR) data Digital Elevation Model (DEM) for RI [16] and the flood maps to determine the water inundation depths. FigurFeig7u. rLeo7c. aLtoiocantioonf eolfeevlaetviaotnioncecretritfiifciacatetessffoorr CChhaarrlleesstotowwnn, R, RI sItustduydayreaareparopvridoevdidbeydthbeyTtohwe nToowf n of CharlCehstaorlwesnto, wRnI., RI
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
