1. Location index for pre-storm and post-storm LIDAR elevations for the Outer Banks, NC (Location 2 on map). Each location includes pre- and post-storm topography as well as topographic change. The green line shows Hurricane Irene’s track.
On the elevation images below, red colors indicate topographic highs, while blues indicate topographic lows. The differences between the pre- and post-storm elevation data sets show where significant changes have occurred. Red colors indicate erosion. For example, oranges and reds on the seaward side of the islands indicate wide-spread shoreline retreat. (In each image, the Atlantic Ocean is on the bottom right.) Blue colors show areas of accretion, such as overwash deposits where waves and surge have moved sand landward.

2. Location 2, Pre- and Post Storm Ocracoke Island, NC,
Aerial Photographs, courtesy of the USGS

3. November 27-December 1, 2009 (pre-storm) Ocracoke Island, NC
Location 2: LIDAR topography from November 27-December 1, 2009 (pre-storm) and August 28-29, 2011 (post-storm) and topographic change (difference) for a portion of Ocracoke Island, NC. “In the pre-storm image, the continuous, relatively high elevations, occurring just seaward of the road, appear to be either natural or human-made dunes. In the post-storm image, the central portion of these dunes was eroded. The difference image shows erosion of the beach and dunes and deposition landward of the road, signs of overwash when waves overtop the beaches and dunes and drive sand inland.” See pre- and post-storm photo comparisons at [ for additional discussion.
RED = HIGH, BLUE = LOW

4. August 28-29, 2011 (post-storm) for a portion of Ocracoke Island, NC
Location 2: LIDAR topography from November 27-December 1, 2009 (pre-storm) and August 28-29, 2011 (post-storm) and topographic change (difference) for a portion of Ocracoke Island, NC. “In the pre-storm image, the continuous, relatively high elevations, occurring just seaward of the road, appear to be either natural or human-made dunes. In the post-storm image, the central portion of these dunes was eroded. The difference image shows erosion of the beach and dunes and deposition landward of the road, signs of overwash when waves overtop the beaches and dunes and drive sand inland.” See pre- and post-storm photo comparisons at [ for additional discussion.
RED = HIGH, BLUE = LOW

5. RED = EROSION, BLUE = ACCRETION
Topographic change (difference) for a portion of Ocracoke Island, NC
Location 2: LIDAR topography from November 27-December 1, 2009 (pre-storm) and August 28-29, 2011 (post-storm) and topographic change (difference) for a portion of Ocracoke Island, NC. “In the pre-storm image, the continuous, relatively high elevations, occurring just seaward of the road, appear to be either natural or human-made dunes. In the post-storm image, the central portion of these dunes was eroded. The difference image shows erosion of the beach and dunes and deposition landward of the road, signs of overwash when waves overtop the beaches and dunes and drive sand inland.” See pre- and post-storm photo comparisons at [ for additional discussion.
RED = EROSION, BLUE = ACCRETION