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Coastal Management

SURFO Special: How can understanding the scenarios of rising sea levels help New England parks prepare for Nor’easters?

Each summer, the University of Rhode Island Graduate School of Oceanography (GSO) hosts undergraduate students from all over the country to participate in oceanographic research. These Summer Undergraduate Research Fellows (SURFOs) have not only been working with GSO scientists, but they also have spent part of their time learning how to communicate this science to the public. Although their research experience was virtual this summer, they still did a fantastic job. Read on to find out what they have been up to, and why they everyone should be as excited as they are about their work.

Louis Borrelli (he/him) is a Physics Major at Saint Vincent College in Latrobe, PA.  He worked this summer with Dr.  Isaac Ginis, Dr. Amanda Babson, and Ph. D. student Mansur Ali Jisan.  His  project is part of a larger effort to help park managers better prepare for increased impacts of Nor’easters in southern New England parks.  A few models were used in there project that need to be validated alongside historical observational data.  This project was not difficult to do virtually as it was mostly data analysis, and the mentor and advisors were available as much as one could ask for.  This experience helped him with many skills academically and professionally.

 

What’s a Nor’easter?

A Nor’easter is an extratropical cyclone. It originates when cold climate from the west meets warm weather from the Gulf Stream near the Mid-Atlantic and New England.  Some compare these to hurricanes as they result in high waves and lots of flooding, but in fact they are very different.  We want to see how climate change and, more specifically, sea level rise, will affect the impacts of Nor’easters in two New England parks, Cape Cod National Seashore, and Boston Harbor Islands National Recreation Area.  We used the Nor’easter from March 1-3, 2018 as our control scenario, and increased the sea level for different scenarios, as it was an impactful storm.  

These impacts could lead to different park facilities being damaged by high water levels.  The park is surrounded by communities of Provincetown, MA, where private lands can also be damaged.  Another area of concern would be the Provincetown Airport. It experienced flooding during the storm in 2018, and the flooding will continue to get worse as the sea level rises, the question is, how much worse will these effects get?

Rising sea levels threaten coastal areas with flooding – and the threat gets worse when winter cyclones hit. Photo by Kelly Sikkema on Unsplash

Understanding the threat of flooding

To simulate the effects of a winter storm, we must validate the models we wish to use.  We did it by comparing the data produced by the model to data recorded at 40 weather stations that recorded either wind speed or water level near those two parks.  The model we use to show the maximum flooding in the areas is the Advanced Circulation (ADCIRC) model.  This model is a combination of precipitation, hydrological, wind, and wave models, but we only used the wave and wind models in this project.  The wind model we use to produce wind in the ADCIRC model is the European Centre for Medium-Range Weather Forecasts (ECMWF).  The wave model we use is the Simulating Waves Nearshore (SWAN) model.  The wave model was validated prior to my project.  

We validated the ECMWF model with the recorded wind speed data and the ADCIRC with the observed water level.  Once we saw that the models produced accurate data, we chose four possible sea level rise scenarios.  These scenarios are shown in Table 1.  The 100 cm scenario was the maximum water depth that the ADCIRC model could handle.  The original scenario was to be 150 cm, but the model did not work with this depth.  

The scenarios which were taken into consideration.  * Indicates a scenario provided by Caffery et al. (2018).  ** Indicates a scenario provided by USACE-2016.

We then modified the ADCIRC model using the four scenarios and used it to  produce plots of maximum flooding in two areas of Cape Cod.  The areas in Figure 1 show the maximum flooding from the March 1-3, 2018 Nor’easter with the water level at the time.

A shows the peak flooding for the northern areas of Cape Cod during the March 1-3, 2018 Nor’easter. B shows the peak flooding for the southeastern part of Cape Cod. The scale of the figure increases from 0 to 4 meters of flooding with blue being 0 and 4 being red. (Mansur Ali Jisan, 2020)

  

 

 

 

 

 

 

 

 

The model runs that were incorporating the sea level rise scenarios are shown in Figures 2 and 3.  

The peak flooding for all four sea level rise scenarios for the northern area of Cape Cod. The closer to red, the higher the level of flooding. (Mansur Ali Jisan, 2020)

 

 

 

 

 

 

 

 

The peak inundation for all four sea level rise scenarios in the southern area of Cape Cod. (Mansur Ali Jisan, 2020)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As can be seen above, the rising sea level causes a significant difference in the flooding, not only in the depth of the flooding but also in the spatial distribution.  As the sea level rise increases, the airport in the northwest experiences deeper and deeper flooding.  The scenario suggests that even a 1 meter increase in the sea level can possibly cut off Cape Cod from the mainland.  

But wait – it can get worse!

Our original plan was to run a simulation in the model of 1.51 meters of sea level rise, but the model did not work with this, so we chose to do 1 meter scenario instead.  This means that the projected sea level rise for if society was to continue life as it is with no additional attempts to lessen the causes of climate change, our highest-level scenario is a half of a meter off of those predictions, so the effects would actually be worse than our highest scenario.  In our highest scenario, it can be seen that the northern part of Cape Cod is cut off of the mainland. This would make it more difficult for relief to come to the population and the park.  

For selected areas between northern and eastern Cape Cod, we found the difference in the maximum water level of the 100 cm scenario and the maximum water level of the scenario with no sea level rise.  The differences for 5 areas of Cape Cod is shown in the table below.

Difference in peak water level of the 100cm scenario and no sea level rise scenario. (Louis Borrelli, 2020)

    This project shows that the sea level rising will affect some areas other than areas in the aspect of flooding, and that predicting the effects of 100 cm of sea level rise is much more complicated than just adding 100 cm of flooding to an area of land.  Even more, the effects  of the climate change could be even worse with rainfall and strong storms. In the future, this project may take precipitation and strong Nor’easters into consideration. 

 

I am a PhD candidate at Northeastern University in Boston. I study regeneration of the nervous system in water salamanders called axolotls. In my free time, I like to read science fiction, bake, go on walks around Boston, and dig up cool science articles.

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