Sea level rise will affect inland waters, too
A workshop held recently at Town Hall that focused on the impact of sea level rise was unlike previous talks on Block Island because it examined the potential impacts on the island’s inner ponds and wetlands rather than just the beachfront.
The workshop, held on Thursday, Sept. 12, was conducted by James Boyd, Coastal Policy Analyst for the R.I. Coastal Resources Management Council and Pam Rubinoff, Coastal Management Specialist from the University of Rhode Island’s Coastal Resource Center. They are working in collaboration with other state, federal and private agencies on a project called Beach SAMP, short for Shoreline Change Special Area Management Plan.
This project is intended to give stakeholders a picture of how their communities and environments may change in the coming years due to rising sea levels as well as to develop tools to manage those changes.
Boyd stressed the importance of maintaining healthy wetlands and salt marshes, not only for the environment but for R.I.’s economy, citing their importance to the fishing industry, their recreational use of the waters and as a tourism attraction. Coastal wetlands act as a shock absorber, buffering the coast from large waves, absorb nutrients from run-off and provide critical habitats for marine and land organisms. Other important considerations involve the impact of rising waters on such public infrastructure as waste-water treatment plants, and private ones such as wells and individual septic systems that may become overwhelmed by storm surges and pollute local waters.
In 2011, The United States Geological Survey mapped detailed elevation models of coastal areas in New England. Using this information, maps have been created of all 21 coastal communities in the state that show how these areas would be impacted under a one- , three- and a five-foot sea level rise. Sea level is currently projected to rise in Rhode Island by 3- to 5-feet over 1990 levels by the year 2100.
The SAMP team has been visiting local communities in order to gather feedback on the maps. They want to know what inclusions in the maps are most useful, and what people feel may be inaccurate or missing from them. So far they have visited all of the south coast communities and are now headed up the Narragansett Bay and over to Aquidneck, Tiverton and the Sakonnet River communities.
For Block Island, the group selected nine maps, three each (one-, three- and five-foot sea level rise scenarios) for the areas of Harbor Pond, Cormorant Cove and Sachem Pond. Rubinoff stressed that the maps come with “caveats,” as changes brought on by individual storms cannot be predicted. The models, based on current topographical elevations, seek to predict what would happen if these areas simply “filled up like a bath tub” in the words of Boyd.
As sea levels rise, the wetlands will attempt to migrate upland; allowing them to do so is vitally important and is one of the CRMC’s priorities. Marshes that have nowhere to go will simply drown.
Despite a small audience comprised mainly of Town Planner Jane Weidman, Town Manager Nancy Dodge, and First Warden Kim Gaffett, as well as some members of the Planning Board and other island organizations, the conversation was lively and productive. While the maps show plat lines of existing lots, and areas that are protected by conservation, audience members thought that it would be helpful to delineate areas in historic districts. They also felt that the maps of Cormorant Cove would be more useful if they were expanded to include the Coast Guard Station. Elevations, while potentially helpful, could simply create too much visual clutter.
In terms of future planning, Weidman thought the information from the maps could be utilized in the “Natural Hazards” chapter of the Town’s comprehensive plan. Socha Cohen of the Planning Board felt that buyers of property along Great Salt Pond, developed or not, might do well to consult the maps when making decisions about future building. Along those lines, a consensus among participants seemed to be that Block Island should focus on the three- and five- foot sea level rise maps due to major storm surges occurring at high tides.
A good example of how the maps could potentially be used for future planning was shown by the maps of Cormorant Cove. The roadway to the Coast Guard Station would already be impacted by just a one-foot sea level rise. According to the map, existing salt marsh would most likely want to migrate up onto the roadbed, effectively flooding the road. Other marsh areas in the area could “drown” if no means of allowing for upland migration were provided. One method, according to Boyd, could involve, slowly and periodically seeding the area with sand so that the marsh itself would effectively rise.
More information on this on-going project can be found at www.beachsamp.org and on Rhode Island Sea Grant’s page on climate change: http://seagrant.gso.uri.edu/climate/. To receive updates on the project and future events, send a request to firstname.lastname@example.org.