Lidar is a new remote-sensing technology that is used to get accurate measurements of land-surface elevations. It is widely implemented by the U.S. geological survey. Author Dean Gesch wanted to see if Lidar could then, therefore, be used to analyze the inundation of Hurricane Katrina on New Orleans to help shape flood relief plans in the future.
Luckily, Lidar data was collected in in 2002, before Hurricane Katrina, and put into the NED in 2005, so it was, in fact, used to plan the flood relief operation. Here is how they did it: first, they collected information on land-surface measurements topography, then used the lidar model they made in GIS applications to make an estimate on how much floodwater a certain area could hold. Mathematicians did this by creating a capacity curve equation. Capacity estimates were based on data from the Lake Ponchartrain gage. Then they made a map showing these capacity levels.
Due to the timeliness of how they mapped out New Orleans, this helped massively with the initial flood response, allowing them to use the data to rescue people from and reconstruct the most flooded areas first.
Gesch, D. (2005). Topography-based analysis of Hurricane Katrina inundation of New Orleans. Science and the Storms: the USGS Response to the Hurricanes of, 53-56.