1. Predicted Sea Level Rise on Plum Island, MA
Jessica Batchelder ‘17
Environmental Studies Program, Colby College, Waterville, ME
Abstract
ArcGIS and NAD1983 Massachusetts Stateplane Mainland FIPS 2001 projection was used to model sea level rise on Plum Island, Massachusetts.  Under high sea level rise conditions of 3m, 81.9% of the buildings on the island will be inundated in addition to a total of 11.06km2 or 75.44% of the islands land area.  86.5% of the wetlands would be inundated, the most loss of any vegetation type on the island. The modeled sea level rise assumes catastrophic conditions such as the melting of the Greenland Ice Sheet (National Snow and Ice Data Center). Based upon elevation data, this model provides a basic analysis of the impacts of extreme sea level rise on Plum Island.
Discussion
The modeled sea level rise shows that Plum Island will lose 75.5% of its area and 82% of all buildings under the most extreme conditions.  In addition to this loss, the immense loss of wetlands will have further implications on the island, as they are a critical ecosystem for storm protection (Plum Island LTER). In addition, the bare soil, or sand dunes, that are located on the western side of the island provide additional barriers in front of waterfront houses.  The loss of the wetlands and sand dunes will cause further loses to the island that cannot be analyzed by this model.
This model is very rudimentary and should not be used by homeowners to evaluate risk of inundation.  Due to limitations on elevation data, the smallest available increments were 1m. By the end of the century, most estimates are only expecting a 0.5m rise in sea level yet this model analyzed the impacts of a 1m, 2m and 3m rise which will most likely not occur within the next century.  However, the modeled conditions of a 3m sea level rise could occur if the Greenland Ice Sheet were to melt. Under this scenario, the National Snow and Ice Data Center predicts that sea level would rise 6m (National Snow and Ice Data Center). Further research could also be incorporated into this model to analyze areas the risks of storm surge from these expected sea level rise conditions to show houses that will still be above water but at risk for flooding during storms.
Introduction
Over the past decade, increased rates of sea level rise have been observed all over the world. The biggest driving factor of this increased rate is climate change (IPCC,2007). By the end of the 21st century, the Intergovernmental Panel on Climate Change estimates a .2m-.5m rise in sea level (IPCC, 2007). Catastrophic changes in sea level rise could occur if the Greenland Ice Sheet were to melt which could cause a sea level rise of up to 6m (National Snow and Ice Data Center). Sea level rise will alter coastlines, inundate critical habitats and devastate many communities. I developed a spatial model to analyze how low, medium and high conditions of sea level rise could impact Plum Island, Massachusetts.
Methods
ArcGIS and NAD1983 Massachusetts Stateplane Mainland FIPS 2001 projection was used to model sea level rise on Plum Island. Land cover data for the four towns that make up Plum Island were downloaded from the Plum Island Ecosystems LTER and combined into one raster using the raster to mosaic tool (Plum Island LTER). A 5m DEM elevation layer from the Massachusetts Office of GIS was used to show elevation data (Office of Geographic Information). All raster layers were converted to a 5mx5m cell size. To show increase in sea level rise, the raster calculator and conditional statements were used to show areas that would be inundated under a 1m, 2m and 3m rise. All buildings on Plum Island were digitized using Zonum Solutions and converted to raster in order to determine the number of buildings that would be inundated under low, medium and high conditions of sea level rise (Zmaps: DigiPoint 3). Low lying inland areas were removed from the analysis using region grouping and Euclidian distance calculations.   
Figure 1. Inundated areas under a 1m, 2m and 3m sea level rise on Plum Island, MA.
Figure 2. Vegetation types on Plum Island, MA
Figure 3. Types of vegetation that would be inundated under a 1m, 2m and 3m sea level rise on Plum Island, MA.
Results
Under low, medium and high conditions of sea level rise, Plum Island will be impacted both in the inundation of buildings and land cover (Table 1).  Under high sea level rise conditions of 3m, 967 of the 1180 buildings on the island will be inundated in addition to a total of 11.06km2 or 75.44% of the islands land area. Wetlands would see the most loss of any of the vegetation types on the island with 86.5% of the wetland area being inundated from a 3m sea level rise (Table 2)
Table 1. The impacts of a 1m, 2m and 3m rise in sea level on area and buildings that would be inundated under each of these conditions on Plum Island, Massachusetts.
Sea Level Rise
Area Inundated (km2)
Percent Inundated (%)
Buildings Impacted
1 meter
0.58
3.96
140
2 meters
8.71
59.41
617
3 meters
11.06
75.44
967
Figure 4. Orthographic image of Plum Island, MA showing inundated areas under a 1m, 2m and 3m sea level rise.
Conclusion
Based upon elevation data, this model provides a basic analysis of the impacts of sea level on Plum Island.  This model shows the number of buildings that would be impacted along with inundated land cover data broken down into vegetation types.  The model could have been expanded to include other implications such as impacts of storm surge and habitat loss.
Table 2. The impacts of a 1m, 2m and 3m rise in sea level on each vegetation type found in the area.  The areas are expressed as a percent of the original area that would be inundated under each condition.
Vegetation Type
Original Area (km2)
Area Inundated 1m Rise (%)
Area Inundated 2m Rise (%)
Area Inundated 3m Rise (%)
Bare Soil
2.87
10.1
27.2
46.7
Coniferous
0.10
5.0
20.0
60.0
Deciduous
1.84
4.9
17.4
40.8
Fine Green
0.14
14.3
64.3
85.7
Impervious
0.52
13.5
50.0
80.8
Water
1.01
20.8
30.7
71.3
Wetlands
7.87
55.4
77.4
86.5
References
IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical fffffScience Basis. Contribution of Working Group I to the Fourth Assessment Report fffffof the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. fffffManning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. fffffCambridge University Press, Cambridge, United Kingdom and New York, NY, fffffUSA.  National Snow and Ice Data Center. (n.d.). Retrieved April 27, 2015, from fffffhttps://nsidc.org/cryosphere/quickfacts/icesheets.html Office of Geographic Information (MassGIS). (n.d.). Retrieved April 27, 2015, from fffffhttp:// Plum Island LTER. (n.d.). Retrieved April 27, 2015, from fffffmbl.edu ZMaps: DigiPoint 3. (n.d.). Retrieved April 27, 2015, from fffffgmaps/digipoint.php  
Figure 5. Inundated buildings  under a 1m, 2m and 3m sea level rise on Plum Island, MA..
Figure 6. Orthographic image of Plum Island MA showing inundated buildings under a 1m, 2m and 3m sea level rise.
Acknowledgements
I would like to thank Dr. Philip Nyhus, Associate Professor of Environmental Studies and Manny Gimond, GIS and Quantitative Analysis Specialist for their help working through technical problems with the model.