From news.appstate.edu:
“Obviously, a four-meter spatial resolution is better than a 30-meter spatial resolution, but it’s more time consuming to obtain and process,” said Monica Davis, an Appalachian State University graduate student. “Our goal is to find the maximum spatial resolution, or range of spatial resolutions, for accurate flood mapping.”

For families and businesses surrounding the Swannanoa River, these few meters matter.

[Davis is] analyzing recent data taken from the Swannanoa River in Asheville in order to construct the most accurate representation of flood extent and depth, and to analyze the amount of damage caused by floods.

The goal of Davis’ research is to accurately depict the topography of the Swannanoa River by identifying the spatial resolution that is best for flood mapping, using Light Detection and Ranging (LiDAR) elevation data provided by the North Carolina Flood Mapping Program. LiDAR is similar to active SONAR; however, LiDAR uses laser pulses of light instead of sound. LiDAR also uses an airborne laser to retrieve data as it reflects off tops of trees, buildings and bare earth. In some states, flood mapping utilizes data retrieved 30 years ago or more, rendering a less accurate 3-D model of the land. Where the old method measured elevation every 10 or 30 meters, LiDAR technology allows for a measurement of four meters or less. ...

Flood mapping determines their insurance policies based on the 100-year flood level, and inadequate data produces inaccurate flood insurance policies. Homes and businesses within the 100-year flood level pay higher insurance premiums, so it is important that the modeled flood level and boundary is accurate.

Furthermore, if a city is unprepared for a major flood, reservoirs may be forced to let go of water at an inappropriate time. “Having an emergency plan in place prior to a major flood event can decrease the overall effects of a devastating flood,” said Davis. “The City of Asheville learned its lesson during the disastrous floods of 2004 created by hurricanes Francis and Ivan. ...

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