Environmental Protection

Lidar Confirms Coastal Impacts of Hurricane Sandy

In a new U.S. Geological Survey analysis of recently collected lidar coastal data, the devastation and future coastal vulnerability of the region after Hurricane Sandy wreaked havoc is clear. The research documented particularly dramatic impacts within the Fire Island National Seashore on Long Island, NY.

Lidar (light detection and ranging) uses lasers to measure elevations in a specific distance or area. Researchers used the lidar data they collected during an airborne survey to construct a high-resolution three-dimensional map of coastal conditions both before and after the storm.

The information the researchers obtained can help scientists and decision-makers identify the areas along the shore that have been made more vulnerable to future coastal hazards in the storm’s wake.

"Coastal dunes are our last line of natural defense from the onslaught of storms and rising seas," said USGS Director Marcia McNutt. "They are dynamic features that retreat from the battering of major storms like Sandy and rebuild in the aftermath; their natural cycle is inconsistent with immobile development."

USGS research oceanographer Hilary Stockdon said that the lidar data show that at Ocean Bay Park, for example, storm surge and waves associated with Sandy demolished protective dunes – and the structures built on top of them.

"In the pre-storm elevation image of Ocean Beach, you can see houses that are sitting right on the sand dune," Stockdon said. "But in the post-storm elevation image, the high dune elevation is gone. The dune and the houses on it were completely washed away."

According to Stockdon and Hapke, the lidar analysis, combined with ground survey data, and pre- and post-storm oblique aerial photography, tell a dramatic story of Sandy’s catastrophic effect on the shoreline and the future coastal vulnerability in this region. It will also help to demonstrate the accuracy of coastal change predictions calculated before the storm in this area.

"This work can help coastal communities understand where they are most vulnerable to future storms," Stockdon said "and help decision makers at all levels create policies that protect their economic, environmental, and ecological health in the coastal areas most susceptible to extreme storm impacts."

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