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|Sea level rise report available online|
|Written by Gillian Smith|
|Wednesday, 14 August 2013 08:45|
After receiving a $30,000 grant for research and conducting a study this year, the final sea-level rise report for Duxbury, Marshfield and Scituate has been posted to the town’s website.
The website boasts the entire study presentation, as well as 25-year sea level rise and storm surge maps, 50-year sea level rise and storm surge maps and 75-year sea level rise and storm surge maps. Duxbury, Marshfield and Scituate are especially vulnerable to sea level rise due to their geography and densely populated coasts. Due to extensive damage sustained over the years from storm-related flood along the coast line, the towns decided to conduct a study to look at the immediate impact of sea level rise, as well as the impact 25, 50 and 75 years from now.
In Duxbury, the study looked at sea level rise in 2038, 2063 and 2088 and specifically looked at the Blue Fish River, Duxbury Beach/Blakeman’s and Washington Street/Snug Harbor. The results of the study pointed to significant sea level rise impacts at Duxbury Beach, Ship Yard Lane Beach and various smaller beaches and landings.
“If beaches are not otherwise nourished and raised, there could be partial or complete loss of some ocean front beaches at high tides,” the report said. “In addition, the potential for increased frequency and intensity of storm events can also lead to additional deteroriation of ocean front beaches.”
For shell fishing, rising sea levels could impact the commercial aquaculture in various ways, though the specific impact is “not well understood at this time,” according to the report. Potential impacts include deeper water that would reduce the amount of time available to access and work the shellfish beds, rising water temperatures that could affect shellfish growth patterns and timing and changes to exist- ing tidal salt marshes that could change nutrient levels in the water, which could affect shellfish growth.
As far as roadways and bridges are concerned, the areas with the highest potential impact are Washington Street in the Snug Harbor area, Powder Point Avenue and King Caesar Road, sections of Bay Road, Pine Point Road, Marginal Road, Gurnet Road and Duxbury Beach Access Road, which provides access to the Gurnet and Saquish areas.
The report said the deck of the Powder Point Bridge appears to be above the storm and surge levels at the 75-year scenario, as do the Eagles Nest and Bluefish River Bridges. However, the approach roads to both bridges will likely be impassable. Additionally, emergency access roads may be impacted, especially for residences on Gurnet Point and Saquish Beach in Plymouth.
“If these access roads to these areas are blocked off, then there is no other emergency egress route to these residential sections,” the report said. “It should be noted that these roads currently do get flooded and closed during astronomical tidal and storm events, so the town already does have a system to deal with emergency access in these locations. However, if nothing is done to change the roads, the frequency and duration of flooding and closures can be expected to increase, putting more strain on the police, fire and public works departments.”
Potential adaptation strategies include: “do nothing,” “protection,” “accommodation,” and “retreat.” The report said doing nothing is not a wise course of action because “eventually the problem will need to be dealt with one way or another.”
Protection strategies include adaptation strategies that try to prevent damage to essential infrastructure by creating a barrier between the rising sea level and the infrastructure. Barriers include sea walls, dikes, bulkheads, levees, flood gates and hurricane barriers. Accommodation strategies allow flood waters to reach a developed area, but damage is minimized or controlled. Examples include raising structures above flood elevations and constructing sacrificial dunes.
Retreat adaptation strategies would be put in place if it is recognized that some areas that are technically not feasible for preventing damage. Examples include property buyouts, relocation of roads and building and new construction.
Next steps include a follow-up analysis to further define potential impacts and formalize groups to advance additional studies and create potential adaptation strategies.
The full report and maps can be accessed via the town’s website at town.Duxbury. ma.us.