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    A Huge Laser-Mapping Project Is Redrawing America

    Written by

    Ben Richmond

    Contributing Editor

    New York FEMA Floodplain Mapping via NY State Dept. of Environmental Conservation

    Just as innovative technology discovered in the space race comes back to taxpayers as consumer goods like mattresses, technology that was honed in the jungles of South America is coming back to America’s literal shore.

    In order to better understand the effects of Hurricane Sandy, and to better prepare for the next huge storm, the US Geological Survey closely examined the moved shoreline of Fire Island, using both conventional field surveys and new sky-mounted, laser-based technology. It’s part of an eight year, billion dollar project to create a digital map of the United States that, if all goes as planned, will lead to new flood-plain maps for FEMA, safer infrastructure, and smarter agriculture.

    In May, researchers announced they had discovered the remains of an abandoned city deep in the jungle in Honduras, using the laser technology called lidar, which stands for light detection and imaging. Flying far above the canopy in a small plane, they were able to map the jungle floor. Lidar can detect changes in elevation smaller than 4 inches, and it revealed the telltale right angles of buildings and roads.

    In the United States, Lidar was used to discover a surface rupture along the Tacoma fault in Washington State, which led to a redesign of a suspension bridge across the Tacoma Narrows (because we all know the consequences of imperfect bridges spanning the Tacoma Narrows).

    The national map project, called the 3D Elevation Program, will replace extant topographical maps that are an average of 30 years old, and will be quite an upgrade in terms of detail. "Historically we've measured accuracy in meters. With lidar, we measure accuracy in centimeters," Larry Sugarbaker, a senior advisor to the USGS, told The Atlantic’s Henry Grabar.

    via USGS

    Following the $50 billion worth of damage done by Hurricane Sandy, infrastructure improvements to the East Coast are welcome, but will require re-examining coastlines to discover the areas most vulnerable to a future large waves or storm surges. The survey of Fire Island quantified just how severely the beach had been hit:

    Post-Sandy measurements of volume loss of the beach and dunes indicated that on average the system lost 54.4 percent of its pre-storm volume. Nearly half (46.6%) of Fire Island was overwashed. In locations where the dunes were not fully breached, they eroded landward by as much as 36 m (22 m on average). The elevation of the beach was lowered by as much as 3 m.

    So with a combination of lidar mapping the shallower depths and coasts, and the deeper seafloor being mapped by boats, the USGS, the US Army Corps of Engineers and NOAA can better understand the changed and ever-changing coastal landscape.

    "Communities will benefit greatly from the higher resolution and accuracy of new elevation information to better prepare for storm impacts, develop response strategies, and design resilient and cost-efficient post-storm redevelopment,” said Kevin Gallagher, associate director for Core Science Systems at USGS.

    Whatever next steps are taken to protect New York—or any coastal community—from the next storm surge, knowing the lay of the land and water is the first step.

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