Incorporated by the U.S. Geological Survey within the National Elevation Dataset, lidar, “light detection and ranging remote sensing,” (1) is used to develop topographic information and assess national elevation variances. Because lidar technology was included within geospatial datasets for Louisiana before Hurricane Katrina, the elevation and “surface-land” research derived from such technology was effective in determining the extent of flooding of the New Orleans area. This previously incorporated data was gathered in 2002 by using light detection to assess the land elevation surrounding Lake Pontchartrain and the Mississippi River. Research found that the land along these rivers was higher than the land in the center of New Orleans, creating a “bowl shape,” (2) as depicted in the map below. Lidar often does not provide precise elevation estimates of water surfaces, as this type of surface alternates; therefore, the water surface elevation “is inferred from surrounding areas or other data sources (2).
After the hurricane, gages placed within Lake Pontchartrain Causeway were used to determine that the elevation of the lake and inundation of New Orleans had “equalized” (3). The magnitude and approximated volume of floodwaters was assessed using previously conducted lidar research as well as water level data provided by a Lake Pontchartrain gage. The graph below demonstrates this integration of data and highlights the “estimated floodwater volume and area within New Orleans” on Sep. 2, 200 and the effect of inundation by the foot to the “cumulative flood volume and area” (4).
Overall, Lidar technology was useful in determining elevation and flood levels as well as the approximated time necessary to transfer floodwater caused by Hurricane Katrina away from New Orleans. Subsequently, the incorporation of lidar elevation data,“ground-based water-level information” (4) and magnitude of flooding within an area “from remote sensing” will allow for water removal plans to be devised, inundation records to be recorded, and efficient, strong construction plans to be carried out.
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Source: Gesch, D. (2005). Topography-based analysis of Hurricane Katrina inundation of New Orleans. Science and the storms: The USGS Response to the Hurricanes of.