The Block Island Times

Study: sea level rise would affect town infrastructure

By Stephanie Turaj | Jul 22, 2013

Within the next 100 years, seas are predicted to rise, and Block Island isn’t going to look the same. Roads and harbors may be flooded, and New Harbor may be cut off from the rest of the town due to flooding, according to a study released this year.

A study by the Town of New Shoreham said that rising seas would affect the following parts of the island: the breakwater in Old Harbor, the ferry loading area, Ocean Avenue, Corn Neck Road, Beach Avenue, and marine facilities at New Harbor.

The draft report of “Block Island Harbors Sea Level Rise Adaptation Study,” was released in July 2013, and was prepared by Town Planner Jane Weidman, various technical experts and 12 town officials.

As part of the document, maps of the island show the effects of one to five feet of increased sea level rise. Various solutions were then proposed to minimize the potential damage to these areas.

“With no changes to infrastructure, the result of three foot [sea level rise] would be the isolation, in terms of public road way access, to a number of areas in and around the village [town] and New Harbor,” said the draft study.

To mitigate the effects of sea level rise, the draft study said that “the Town should evaluate its land use and building regulations to consider future development and redevelopment in the most critically impacted inundation areas.”

The draft study said that from 1990 to 2050, sea levels are projected to rise by one foot or more. By 2100, the seas may rise three to five feet. This sort of rise would result in higher tides and higher storm surges.

“The combination of these factors — higher sea levels and high tides, and the greater frequency of more severe storm surges — will result in greater coastal flooding and erosion, and more widespread property and infrastructure damage,” said the draft study.

As part of the damage, the draft study said, “under the worst case scenario, 5 ft [sea level rise], the breakwater that forms the harbor of refuge would be partially inundated, along with up to half of the ferry loading area.”

The study also says some roads would be flooded if sea levels rise by three feet: “Ocean Avenue, between the intersection with Corn Neck Road (Bridgegate Square) and Beach Avenue, would be inundated in three areas.”

It continues: “Most dramatically, the section of Ocean Avenue between the Hog Pen and Payne’s Dock, including its intersection with West Side road, the major road connecting New Harbor with the outlying residential areas, would be completely flooded on an average high tide.”

The result of road flooding could isolate various areas of the town, such as areas on Ocean Avenue west of Bridgegate Square. Also, docks at New Harbor would be affected.

But the study said some other roads — Spring Street, High Street and Old Town Road — would not be directly affected by sea level rise. These roads could, however, be affected by increased storms.

The study recommends various engineering options to mitigate the effects listed above. For example, the elevation of the piers and breakwater can be increased. Also, roads that will be critically affected can either be abandoned, raised to a higher elevation, reconstructed as a causeway, or protected with a sea wall.

In December 2011, the Town of New Shoreham received a grant from the U.S. Gulf of Maine Association, with financing provided by The National Oceanic and Atmospheric Administration (NOAA), to perform this study.

The study’s goals “include the development of mapping that indicates the impact of various sea level rise and storm surge scenarios on the harbors and village areas, structural engineering concepts to address the impact of this rising sea level on the island’s marine infrastructure, and a contingency plan to respond to the potential inundation of the connecting roadways and bridges.”

There will be a public information session held on this study next week, Tuesday, July 23 at 4:30 p.m. at Town Hall.

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