of national spending priorities. Certainly the data arising from Elevation for the Nation will have many beneficial uses beyond floodplain mapping and management.

The current study was conducted in a short time to address very specific questions about the mapping technologies used to produce floodplain maps. As such, the committee did not have the resources or scope to examine in detail many important issues related to flood map accuracy. The committee suggests, for example, that analysis of a selection of updated flood maps could be useful to compare the quantitative effects of using lidar versus using conventional 10-meter or 30-meter NED information derived from USGS topographic maps to provide the elevation data. In a new, two-year study, beginning in early 2007, FEMA has separately requested the National Academies to undertake a distinct evaluation of flood map accuracy, including an examination of the whole range of uncertainty in flood mapping arising from uncertainty in flood hydrology and hydraulic modeling, as well as uncertainty in land surface elevation. The committee hopes that the present report provides solid input to the upcoming study and helps to further objective examination of the most cost-effective methods needed to support the nation’s floodplain mapping and management.

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