Floodplain maps serve as the basis for determining whether homes or buildings require flood insurance under the National Flood Insurance Program run by the Federal Emergency Management Agency (FEMA). Approximately $650 billion in insured assets are now covered under the program. FEMA is modernizing floodplain maps to better serve the program. However, concerns have been raised as to the adequacy of the base map information available to support floodplain map modernization. Elevation Data for Floodplain Mapping shows that there is sufficient two-dimensional base map imagery to meet FEMA's flood map modernization goals, but that the three-dimensional base elevation data that are needed to determine whether a building should have flood insurance are not adequate. This book makes recommendations for a new national digital elevation data collection program to redress the inadequacy. Policy makers; property insurance professionals; federal, local, and state governments; and others concerned with natural disaster prevention and preparedness will find this book of interest.

Congress appropriated $5 million in FY2000 for a Flood Map Modernization Fund (FMMF), the eventual source of funding for the Federal Emergency Management Agency's (FEMA's) long-term effort to modernize the nation's flood map program. As part of the Flood Map Modernization Initiative (FMMI), FEMA has been converting paper flood insurance rate maps (FIRMs) to digital electronic format, or DFIRMs. DFIRMs contain more accurate spatial measurements and digital data associated with flood risk and are developed with a geographic information system (GIS). The GIS also facilitates periodic updating of flood maps, as required by Congress, and helps determine flood insurance rates. Many DFIRMs are now available over the Internet from FEMA. Initial FMMI funding was requested in the Veterans Administration Housing and Urban Development (HUD), and independent Agencies Appropriations Act of FY2002 (P.L. 107-73). However, regular annual appropriations did not begin until FY2003. Since FY2004, Department of Homeland Security appropriations for FEMA have funded FMMI. To date, more than $800 million has been provided. Congress has also provided supplemental spending authority for the FMMI that is offset by internally collected flood-map-related service fees. This report will be updated as events warrant.