Assessing Storm Damage: Hurricane Sandy, Future Hurricanes
and Sea-Level Rise
Purpose of the exercise: Beginning GIS students view pre-storm and post-storm views of coastal areas
on Long Island and compare these areas to places along the Rhode Island coast that are similarly
vulnerable to hurricane damage. They also look at patterns of development on filled-in salt marshes in
both places and learn how such development affects coastal flood risks. They will gain experience in
looking at the kinds of damage that hurricanes do to barrier beaches and salt ponds and also in working
with remote-sensing images in ArcGIS. This exercise is written for ArcGIS 10.2.
Introduction
Hurricane Sandy formed near Jamaica on October 22, 2012 and broke up on November 2, 2012. It was a
Category 3 hurricane when it hit Cuba and a Category 2 hurricane when it hit the northeast US. The
storm killed more than 200 people and caused more than $68 billion in damage.
Track of Hurricane Sandy. Blake et al., 2013, Figure 2
Developed 2015 by the Integrated Geospatial Education and Technology Training (iGETT) project, with funding
from the National Science Foundation (DUE-1205069) to the National Council for Geographic Education.
Opinions expressed are those of the author and are not endorsed by NSF. Available for educational use only. See
www.igettremotesensing.org for additional remote sensing exercises and other teaching materials.
Sandy came onshore in New Jersey on October 29. It was the largest Atlantic hurricane ever recorded-1150 miles across—and caused coastal floods as far east as Cape Cod. Coastal flooding occurred in
Narragansett Bay and along the southern Rhode Island coast, increasing in severity to the west (closer to
the center of the storm), but the damage was slight compared to western Long Island and the New Jersey
coast. Flooding in Rhode Island was around 4 feet above normal, while closer to the center of the storm
it reached a maximum of 9 feet.
Inundation map for Hurricane Sandy. Blake et al., 2013, Figure 24.
Rhode Island has not always been so lucky. Large hurricanes in 1938 and 1954 hit the state directly and
devastated the coast. Since then, sea level has risen. The barrier beaches have steadily eroded, and
people continue to build on them. Looking at the damage that Sandy did to coastal areas closer to the
storm center can show us what could happen to Rhode Island in the next storm.
Part 1. Barrier beach overwash and breaches
The south coast of Long Island has extensive barrier beaches with salt marshes and salt ponds behind
them. Fire Island, when it was a single barrier island, was more than 30 miles long. It is in the central
part of the south coast. Hurricane Sandy breached Fire Island, dividing it in two. In this exercise, you
will examine aerial photos of Fire Island before and after the breach.
Note to instructor: The pre-storm image is a mosaic of aerial photos taken in 2010 by the New York
Statewide Digital Orthoimagery Program (NYSDOP). You can preload this onto students’ computers or
give them instructions to download it themselves.
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Instructions for students or instructor, using ArcGIS 10.2.2:

Open a new blank map in ArcGIS.

Click the Add Data button and select GIS Servers, then Add ArcGIS Server. A box opens
with a field for a Web address. Type in http://www.orthos.dhses.ny.gov/arcgis/services .

When a list of years comes up, choose 2010. The coordinate system for the data is WGS
1984 Web Mercator Auxiliary Sphere.
A set of aerial photos will load into your map.

Open the Go To XY tool and type in the following coordinates: 40 43 26.92 N, 72 53 50.77
W. When the map zooms to the correct location, click on the Add Point icon (fourth from the
left in the Go To XY box) to mark the location.
This is the part of Fire Island that was breached in 2012. It is part of the Otis Pike Fire Island High Dune
Wilderness, so it is not populated. The salt pond here is called Bellport Bay. It is the eastern part of the
much larger Great South Bay.

Use the Measure tool with the units set to feet. Measure the beach just south of your lat-long
point from the ocean side to where the brown salt marsh begins.
1. How wide is the beach?

Open a web browser and go to storms.ngs.noaa.gov/storms/sandy/ . This is a map that has an
overlay of aerial photos taken in 2012 immediately after Sandy.

In the Search box, type in “Patchogue” and select “Patchogue” in the list that appears. The
map zooms to the same section of Fire Island as in your 2010 image in ArcMap.

Find the breach in the barrier island.

Switch between the two images to answer the following questions.
2. Do you see evidence of overwash of sand into Bellport Bay (lobes of sediment in the water)?
3. In the 2010 image, there is a long boardwalk that ends in a T-shaped pier in Bellport Bay. What
happened to the boardwalk when the storm breached the barrier island?
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4. What happened to the island just northeast of the breach?

Save your New York map. You will be using it again.
Now we can look at a similar stretch of beach in southwestern Rhode Island. Atlantic Beach is a barrier
island in Westerly.
Note to instructor: Recent aerial photos can be downloaded from the Rhode Island GIS website,
www.edc.uri.edu/gis/. The photos can be preloaded onto student computers or the students can
download it.
Instructions for students or instructor, using ArcGIS 10.2.2:

Open a new blank map in ArcGIS.

Click the down arrow next to the “Add Data” tool.

Choose “Add Data from ArcGIS Online”.

When the ArcGIS Online box appears, type “Rhode Island” into the search box.

Select “Rhode Island Aerial Photographs 2011”.
A set of aerial photos loads into your map.

Open the Go To XY tool and type in the following coordinates: 41 19 32.32 N, 71 47 25.59
W. When the map zooms to the correct location, click on the Add Point icon (fourth from the
left in the Go To XY box) to mark the location.

Use the Measure tool with the units set to feet. Measure the beach from the road to the ocean
edge.
5. How wide is the beach? Is it similar to Fire Island?

Save your Rhode Island map. You will be using it again.
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The Rhode Island Coastal Resources Management Council has a series of maps that show the changes in
the Rhode Island shoreline since 1939. In most places beaches are retreating as sea level rises.
Go to www.crmc.ri.gov/maps/maps_shorechange.html

In the first list, “Watch Hill to Narragansett Pier (South Shore)”, click on the
“Westerly_Atlantic Beach” link (third from the bottom) to see the shoreline change for
Misquamicut.

The maps are PDFs. You will have to zoom in to see them properly. Hover or click near the
center of the bottom of the page and click on the magnifying glass with the plus sign in it.

The numbered black lines that divide the beach into sections are beach transects.

The yellow numbers show the average change per year in feet and meters. The red numbers
show the total change from 1939 to 2004 in feet and meters. Negative numbers mean that the
beach has retreated landward. Positive numbers mean that the beach has built seaward.

The red lines are the 1939 shoreline, based on aerial photos taken at the time, and the blue
line is the modern shoreline.
6. Based on what you see, can you tell if the 1938 hurricane breached the barrier in this area?
7. Which beach transect line shows the greatest amount of beach change? What is the rate in feet per
year?
8. Given the evidence, is it likely that Atlantic Beach could be breached by a hurricane more easily now
than in 1938?
Breaches affect the salt ponds behind barrier islands. Salinity and currents can increase, and future storm
surges will enter the pond, but better tidal flushing can reduce pollution. Breaches are natural and can be
beneficial to salt pond life.

Save your New York map. You will be using it again.
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Part 2. Flooding and damage to coastal structures
Overwash is natural and gradually moves barrier beaches inland over time. Structures on a beach block
overwash. Instead of washing over the beach to the salt pond, waves hit the structures, often damaging
or undermining them, and erosion increases. Instead of being deposited in the salt pond, sand can be
dumped out at sea. Over time this shrinks the barrier beach.
The storm surge from Sandy flooded structures in coastal areas and dumped sand around them. This can
be seen in post-storm aerial photos of Rockaway Beach, Queens, at the west end of Long Island.

Open your New York aerial photo map in ArcGIS.

Open the Go To XY tool and type in the following coordinates: 40 34 51.17 N, 73 49 52.43
W. When the map zooms to the correct location, click on the Add Point icon (fourth from the
left in the Go To XY box) to mark the location.
This is Rockaway Beach. This area is extensively built up.

Open a web browser and go to storms.ngs.noaa.gov/storms/sandy/ .

In the Search box, type in “Beach 108th Street” to see this area after Sandy.

Switch between the two images to answer the following questions.
1. How far inland did floodwaters dump sand? Use the Measure tool in ArcGIS with the units set to feet.
Use the post-storm photos as a guide and measure from the shoreline.
A topographic map will clarify how vulnerable this area is to flooding in a hurricane.

In your ArcGIS map, click on the down arrow next to the “Add Data” tool and select “Add
Data from ArcGIS Online”.

In the search box in the ArcGIS Online window, type “Topography”.

Select “USA Topo Maps” to download a layer of USGS topographic maps.

Drag the topography layer to the top of the Table of Contents so it is visible.

Zoom in to see the most detailed topographic map.
2. The contour interval on land is 5 feet. What is the highest elevation with a contour line? Did the
floodwaters exceed this elevation?
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3. Did the floodwaters reach the sewage treatment plant on the north side of the barrier beach?
Rhode Island’s barrier beaches are not as densely developed as this one but they can still have a lot of
houses and other structures on them. Let’s see how Atlantic Beach in Westerly compares in elevation to
Rockaway.

Open your Rhode Island map.

Click on the down arrow next to the “Add Data” tool and select “Add Data from ArcGIS
Online”.

In the search box in the ArcGIS Online window, type “Topography”.

Select “USA Topo Maps” to download a layer of USGS topographic maps.

Drag the topography layer to the top of the Table of Contents so it’s visible.

Zoom in to see the most detailed topographic map.
4. The contour interval on land is 10 feet. Does any part of Atlantic Beach have a contour line greater
than 10 feet?
5. The storm surge from the 1938 hurricane was 10-12 feet high. Would Atlantic Beach be mostly
inundated if a similar storm were to strike it now? Would the cottages along Atlantic Avenue escape
flooding?

Save your Rhode Island map.
Part 3. Salt marshes
Salt marshes are part of the barrier beach system. They help to absorb the force of storms. A salt marsh
can absorb more water when it is left in its natural state than when it is filled in and built on.
Unfortunately, many of the salt marshes in the northeastern U.S. have been filled and built on or
otherwise degraded by pollution, dredging, invasive species, and rising sea levels. Rhode Island has lost
thousands of acres of salt marshes since the start of European settlement. Many have been filled with
material dredged from navigational channels.
Communities that are built on former salt marshes are at increased risk of flooding in hurricanes. They
are right on the water, at a low elevation. Examining older maps and comparing them to current aerial
photos can demonstrate the extent to which former salt marshes have been filled in and built on.
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
Open your New York aerial photo map in ArcGIS.

Open the Go To XY tool and type in the following coordinates: 40 47 59.19 N, 73 39 04.50
W. When the map zooms to the correct location, click on the Add Point icon (fourth from the
left in the Go To XY box) to mark the location.
This is Oneck, an area in Westhampton Beach on Long Island. Note that a stream flows through a
narrow strip of salt marsh in the middle of a developed area.

In the Table of Contents, put the 2010 aerial photo layer above the topographic map layer.
Toggle the aerial photo layer on and off.
Wetlands are designated on topographic maps with this symbol:

Make sure the topographic map layer is visible. In the
toolbar, click on the Measure tool (the ruler). The
Measure dialog box opens.

Click on the polygon, the second symbol from the left in the Measure box, for Measure an
Area.

Click on the small triangle next to the . In the pull-down menu, choose “Area” and set the
units to acres.

Click and drag to draw a polygon around the wetland area in Oneck. Double-click when you
are done to make the polygon disappear. The Measure dialog box remains open and shows
you the area of the polygon.
1. What is the area of the wetlands in Oneck on the topographic map, in acres?

Look at the topographic map layer and draw another polygon around the undeveloped salt
marsh close to the stream.
2. What is the area of the wetlands around the stream, in acres?
3. Does this area have the same capacity to absorb floodwaters in 2010 as it did when the topographic
map was made in the mid-20th century?
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
Open your Rhode Island map and go back to Atlantic Beach. Compare the area of salt marsh
around Winnapaug Pond in the topographic map to the aerial photo.
4. Has there been significant salt marsh loss around Winnapaug Pond since the topographic map was
made?
It is easier to see salt marsh loss on parts of Long Island than in Rhode Island because much of it has
been more recent and the old marsh can be seen on fairly new maps. Also, Long Island has more salt
marshes on the mainland side of the salt ponds. These tend to be developed rather than those on the
barrier beach side. Rhode Island’s south coast is more hummocky and has fewer salt marshes on the
mainland side of the salt ponds.
The filling of coastal waters and wetlands began in Providence in the 1700s. Much of downtown was
once a cove and marshland. Downtown was flooded to depths of more than 10 feet in places by
hurricane storm surges in 1938 and 1954. The Fox Point Hurricane Barrier was built across the
Providence River in the 1960s to keep this from happening again.
You can see the consequences of the city’s expansion into low-lying areas by looking at a hurricane
inundation and evacuation map for Providence.

Open a web browser and go to
http://www.riema.ri.gov/resources/emergencymanager/prepare/evacuation.php

Open the hurricane evacuation map of Providence. Zone A (red) is likely to be inundated in a
Category 1 or 2 hurricane. Zone B (yellow) is likely to be inundated in a Category 3 or 4
hurricane. An area that can be flooded in a Category 1 or 2 storm will also be flooded in a
Category 3 or 4 storm.

The maps are pdf files. You can move around with the sliders at the edges of the browser
window.
5. The Providence map has a Zone C (orange). What would cause flooding in Zone C on the map? (Read
the text box “Notes and Sources” on the right side of the map.)
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There is no easy answer to the problem of how we should handle rising sea levels, increasing
population, and future hurricanes!
References
American Littoral Society. Assessing the Impacts of Hurricane Sandy on Coastal Habitats. American
Littoral Society for the National Fish and Wildlife Foundation, December 17, 2012.
crssa.rutgers.edu/projects/coastal/sandy/doc/ALS%20NFWF%20Final%20Assessment%20Report%201
21712.pdf
Blake, E.S., T.B. Kimberlain, R.J. Berg, J.P. Cangialosi, and J.L. Beven II. Tropical Cyclone Report.
Hurricane Sandy (AL182012), 22-29 October 2012. National Hurricane Center, NOAA, February 12,
2013.
www.nhc.noaa.gov/data/tcr/AL182012_Sandy.pdf
Tanski, J., H. Bokuniewicz, and C. Schlenk, Eds. Impacts of Barrier Island Breaches on Selected
Biological Resources of Great South Bay, New York. Final Report, March 2001. New York Sea Grant
(State University of New York and Cornell University), 2001.
http://www.seagrant.sunysb.edu/cprocesses/pdfs/BarrierBreaches.pdf
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