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Coastal and Marine Geology Program > St. Petersburg Coastal and Marine Science Center > Storm Impacts and Vulnerability of Coastal Beaches > Research > Assess Coastal Impacts of Hurricane Sandy and Accuracy of Pre-Storm Forecasts

Hurricane Sandy Response - Storm Impacts and Vulnerability of Coastal Beaches

Assess Coastal Impacts of Hurricane Sandy and Accuracy of Pre-Storm Forecasts

Hurricane Sandy, the largest Atlantic hurricane on record, made landfall on October 29, 2012, and impacted a long swath of the U.S. Atlantic coastline. Many areas that had been hit by Hurricane Irene in August 2011 were again battered by strong waves and surge. The barrier islands were breached in a number of places and erosion of the beach and dunes occurred all along the mid-Atlantic coast. This was the most destructive storm to impact this coastline since an extremely powerful nor'easter in December of 1992.

Using the latest wave and surge information available as the hurricane was making landfall, USGS predicted the likelihood of a range of coastal change impacts within the region affected by the storm. Collision was very likely for the majority of the sandy beaches along the Virginia, Maryland, Delaware and New Jersey coasts with widespread overwash also very likely in many areas. Along the south shore of Long Island, New York, the models predicted extensive beach and dune erosion as well as intermittent overwash.

The USGS is working to develop quantitative methods to evaluate the accuracy of these pre-landfall predictions of coastal change. Using lidar-based surveys of beach topography, coastal change impact metrics such as dune-elevation change, shoreline change and beach volume change, along with pre- and post-storm photo comparisons can be used to verify pre-landfall predictions. Coastal change datasets are available for download through our web mapping service (http://olga.er.usgs.gov/sandy/). State-by-state observations of these coastal change impact metrics are accessible through the links below.

North Carolina | Virginia | Maryland and Delaware | New Jersey | New York

North Carolina

Extreme dune elevation changes of 4 m or more were observed along much of the Outer Banks of North Carolina. From Cape Hatteras north to Oregon Inlet (distance from landfall (DFL) = -420 km, negative numbers indicate locations to the south of landfall) nearly 14% of the dunes experienced 2 m or more in dune height erosion. In Rodanthe, storm surge and waves eroded the dunes and the beach, depositing sand inland and shifting the shoreline landward. Prior to the storm several houses sat on top of, or just seaward of, the dunes or highest elevations on this part of the island. Dune erosion and landward migration of the shoreline has left many of these houses more vulnerable to future storms. Storm surge and waves produced overwash that deposited sand on the coastal roads. Further north, waves eroded the face of dunes in Corolla, N.C.

Hurricane Sandy Pre- and Post-Storm Photo Comparisons - North Carolina

Hurricane Sandy Pre- and Post-Storm 3D Lidar Topography - North Carolina

Graphs of Hurricane Sandy dune-elevation change
Fig. 1. Hurricane Sandy dune-elevation change (A), shoreline change (B), and beach-volume change (C) between August 2009 and November 2012 for the North Carolina barrier island coast. Vertical dashed lines indicate the center of Cape Lookout, Ocracoke Island, and the towns of Rodanthe, Nags head and Corolla, respectively. Horizontal axis is distance from landfall (DFL) in kilometers where negative numbers indicate areas south of landfall, and positive numbers indicate areas north of landfall. [larger version]
Aerial photos of Rodanthe, NC beach erosion
Fig. 2. Oblique aerial photographs of Rodanthe, N.C. View looking west across the North Carolina shore. Beach erosion moved the shoreline landward to reach houses built on the beach. The yellow arrow in each image points to the same feature. [larger version]

Virginia

Along the undeveloped Virginia coastline south of Virginia Beach, relatively little volume change occurred and high dunes averaging 6.6 m in elevation protected against overwash and inundation. However, waves and elevated water level contributed to dune erosion and scarping from the North Carolina/ Virginia border northward. For the approximately 5 km length of the coast centered on Virginia Beach, the beach is backed by a boardwalk, which represents the peak dune height here. The boardwalk remained intact through Hurricane Sandy therefore dune height is unchanged and dune erosion here is zero. However, volume loss and narrowing of the beach occurred in front of the boardwalk. Virginia's barrier island system north of the mouth of Chesapeake Bay experienced extensive landward deposition of sand as low dunes were overtopped by waves and surge. North of Wallops Island, the storm response along Assateague Island varied spatially with dune morphology. Much of the southern end of Assateague Island experienced erosion and volume loss as sand was transported landward to form large overwash deposits. Breaching occurred through the narrow and low-lying beach just north of Little Toms Cove (distance from landfall (DFL) = -190 km, negative numbers indicate locations to the south of landfall). Dunes are larger for the middle section of Assateague Island, averaging 4.5 m in height. Elevated water levels and storm-driven waves eroded the dune face causing scarping along the entire extent of the Assateague coastline but dune height remained intact. Overwash occurred only in limited areas where previous storms cut through the line of dunes.

Hurricane Sandy Pre- and Post-Storm Photo Comparisons

Hurricane Sandy Pre- and Post-Storm 3D Lidar Topography

Graphs of Hurricane Sandy dune-elevation change
Fig. 3. Hurricane Sandy dune-elevation change (A), shoreline change (B), and beach-volume change (C) between November 2009 and November 2012 for the Virginia coast. Vertical dashed lines indicate the center of Virginia Beach, Smith Island, and Wallops Island. Horizontal axis is distance from landfall (DFL) in kilometers where negative numbers indicate areas south of landfall, and positive numbers indicate areas north of landfall. [larger version]
Aerial photos of Virginia barrier island beach erosion
Fig. 4. Oblique aerial photographs of Virginia's barrier-island shore. View looking west across Virginia’s shore. A higher dune ridge on the left (south) side of this scene suffered erosion, but no overwash. To the right (north), lower dunes were eroded and sand was transported inland as overwash. The yellow arrow in each image points to the same feature. [larger version]

Maryland and Delaware

The majority of the northern end of Assateague Island was fronted by a 2 m high berm prior to Hurricane Sandy. Storm waves and elevated water levels destroyed the majority of this low dune structure, carrying sand inland and creating overwash deposits in the bay behind the island in narrow, low-lying places. In the few places along this stretch where a dune existed that exceeded the 2 m high berm, the dune crest remained intact.

While the dunes along the developed coastline of Maryland from Ocean City Inlet northward remained largely intact, waves and surge generated by Sandy eroded and narrowed the beaches. The greatest amount of dune erosion in Maryland north of Assateague Island occurred just north of the Ocean City inlet where a dune elevation reduction of 2 m was observed and the Ocean City Fishing Pier was damaged.

In October 2011 through February 2012, a renourishment project was completed that spanned the beaches from Fenwick Island, Del. (DFL = -121 km) north to Lewes Beach just south of Cape Henlopen. Sand was pumped onto face of the beach, increasing beach width, and dunes were constructed. Despite this addition of sand, Delaware beaches from Bethany Beach to just south of Dewey Beach (DFL ~ -100 km) suffered significant dune erosion, volume loss and shoreline retreat. Areas where the created dunes and widened beach system remained intact after the passage of Sandy appear as positive shoreline and volume change.

Pre and Post-Storm Photo Comparisons

Pre- and Post- Storm 3D Lidar Topography

Graphs of Hurricane Sandy dune-elevation change

Fig. 5: Hurricane Sandy dune-elevation change (A), shoreline change (B), and beach-volume change (C) between September 2010 and November 2012 for the Maryland and Delaware coasts. Vertical dashed lines indicate the center of Assateague Island, Ocean City and Bethany Beach, and Cape Henlopen. Horizontal axis is distance from landfall (DFL) in kilometers where negative numbers indicate areas south of landfall, and positive numbers indicate areas north of landfall. [larger version]
Aerial photos of Assateague island beach erosion

Fig. 6: Oblique aerial photographs of Assateague Island, Md. View looking northwest across the Maryland shore. Storm waves and surge overtopped the low dunes in this location, and overwash moved sand across the island and into the bay. The yellow arrow in each image points to the same feature. [larger version]

New Jersey

Destructive waves and storm surge associated with Sandy severely eroded the beach and dune systems that represented, in many places, the first line of defense for the New Jersey coastline. The majority of the New Jersey coast from Brigantine, where Sandy made landfall, northward experienced severe dune erosion of 2 to 6 m vertical loss. Along the undeveloped barrier coast from Brigantine to Beach Haven (DFL ~ 16 km) dunes that averaged 3.2 m in peak elevation pre-storm were eroded in height by an average of 1.7 m. The dunes along New Jersey's Island Beach State Park (DFL = 47-60 km) were also severely impacted with an average elevation loss of 1.4 m and a mean loss of sand volume from the beach of 69.0 m3/ m along the barrier island dune system. Waves atop elevated water levels eroded the face of the dunes, resulting in dune scarping and breaching of the dune line in places allowing waves to carry sand inland and deposit sand on roads and in parking lots.

The greatest impacts from Sandy were observed along the shoreline from the northern boundary of Island Beach State Park north through Mantoloking, N.J. (DFL = 76 km). Dunes here experienced an average of 2.7 m elevation loss. In Seaside Heights, for example, maximum dune elevation erosion of 7 m was observed and many oceanfront houses were severely damaged. Storm waves and surge destroyed the Seaside Height Pier and the boardwalk in places, eroded the beach, overwashed dunes and washed sand inland, damaging or destroying homes. In Mantoloking, waves and surge breached the narrow island in several locations, cutting through roads and homes and washing houses into Barnegat Bay.

Pre and Post-Storm Photo Comparisons

Pre- and Post- Storm 3D Lidar Topography

Graphs of Hurricane Sandy dune-elevation change

Fig. 7: Hurricane Sandy dune-elevation change (A), shoreline change (B), and beach-volume change (C) between October and November 2012 for the New Jersey coast. Vertical dashed lines indicate the center of Cape May, the communities of Atlantic City and Seaside Heights, and Sandy Hook, N.J. Horizontal axis is distance from landfall (DFL) in kilometers where negative numbers indicate areas south of landfall, and positive numbers indicate areas north of landfall. [larger version]
Aerial photos of Seaside Heights beach erosion

Fig. 8: Oblique aerial photographs of Seaside Heights, N.J. View looking west across the New Jersey, shore. Storm waves and surge destroyed the dunes and boardwalk and deposited sand on the island, covering roads. The red arrow points to a building that was washed off of its foundation and moved about a block away from its original location. The yellow arrows in each image point to the same features. [larger version]

New York

Some of the regions of New York hardest hit by Sandy storm surge include the highly developed communities of Coney Island, the Rockaway Peninsula and Long Beach barrier island (DFL = 131-145 km). Waves and surge attacked dunes averaging 4.3 m in elevation in this region, overtopping the dunes and transporting sand into coastal communities and causing an average of 1.4 m of vertical dune erosion. Along Fire Island, a mean dune-height erosion of 2 m was observed with dune erosion as high as 5 m in many places. Nearly half of the island's dunes experienced overwash resulting in deposition of sand landward and an overall flattening of beach topography. For example, overwash of the dunes at Ocean Bay Park, just east of Ocean Beach, N.Y., resulted in the transport of large volumes of sand inland from the beach system, severe decrease of dune height and significant property damage. Breaching occurred in several locations along Fire Island, including at Old Inlet (the location of breaching during previous storms, DFL = 192 km) where volume loss and shoreline retreat are apparent. Positive shoreline change observed along much of Fire Island is evidence of recovery of the seaward-edge of the beach system immediately following the passage of the storm. A more detailed analysis of coastal changes occurring on Fire Island can be found on the Fire Island Coastal Change project webpage.

From Moriches Inlet east to Montauk, higher dunes (on average 6.6 m in height) protected much of the coastline from overwash and inundation, and the storm surge threat lessened along the eastern portion of Long Island (for example, a peak of approximately 1.8 m above normal tide was reported at Montauk, Blake and others, 2013) resulting in mean dune erosion of 1.0 m. However, several narrow and low-lying places were breached during the storm including Cupsogue Beach just north of Moriches Inlet and W. Scott Cameron Beach south of Mecox Bay (DFL = 240 km).

Pre and Post-Storm Photo Comparisons

Pre- and Post- Storm 3D Lidar Topography

Graphs of Hurricane Sandy dune-elevation change

Fig. 9: Hurricane Sandy dune-elevation change (A), shoreline change (B), and beach-volume change (C) between May 2012 and November 2012 for the Fire Island, N.Y. coast (black) and between August 2010 and November 2012 for the rest of Long Island, N.Y. (gray). Vertical dashed lines indicate the location of Staten Island, the centers of Jones and Ocean Beaches, the locations of Moriches Inlet, Fire Island, Southampton and Montauk. Horizontal axis is distance from landfall (DFL) in kilometers where negative numbers indicate areas south of landfall, and positive numbers indicate areas north of landfall. [larger version]
Oblique aerial photographs of Ocean Bay Park, Fire Island, N.Y.

Fig. 10: Oblique aerial photographs of Ocean Bay Park, Fire Island, N.Y. The view is looking northwest across Fire Island towards Great South Bay. Overwash from the beach and narrow dunes carried sand inland towards the interior and bayside of the island, and numerous houses were destroyed or severely damaged. The yellow arrows in each image point to the same features. [larger version]

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