Sea Level Impacts on Salt Marshes: Beach SAMP updates

October, or “Salt Marsh Month” as declared by Rhode Island Governor Lincoln Chafee to highlight this rapidly declining landscape, is winding down, but efforts to restore and protect salt marshes are far from over.

Many town and state officials, as well as researchers, gathered for the R.I. Shoreline Change Special Area Management Plan (Beach SAMP) meeting last week to hear speakers from the Coastal Resources Management Council (CRMC), Save the Bay, and The Nature Conservancy discuss the current status of salt marshes throughout the state, restoration efforts underway, and what changes we can expect to see in the future with regard to sea level rise.

Salt marshes are estimated to be worth $6,417 per acre for activities related to recreational and commercial fishing.

The Sea Level Affecting Marshes Model (SLAMM) has been developed to identify existing marsh conditions and vulnerable areas, and provide multiple future scenarios given projections of 1 to 5 feet of sea level rise. Maps developed by SLAMM for all of the 21 Rhode Island coastal communities are currently under review by the CRMC to adopt for “planning purposes” by 2015. +Read More

TIdal Marsh SLAMM Maps: Current conditions vs. One foot of sea level rise

TIdal Marsh SLAMM Maps: Current conditions vs. One foot of sea level rise

“These maps project a loss of 1,895 acres of Rhode Island salt marsh with a 3-foot sea level rise,” said Jim Boyd of CRMC, noting that the SLAMM was developed as a result of the North Kingstown pilot project to assess vulnerable infrastructure and impacts of sea level rise on salt marshes. “We recognized we needed to look at this statewide.”

According to Boyd, the economic value of salt marshes related to recreational and commercial fishing activities is estimated to be $6,417 per acre. These marshes, he said, provide the habitat necessary to support an $81 million commercial fishery and $208 million recreational fishery in Rhode Island.

Rhode Island has already lost 53 percent of its salt marshes, according to Wenley Ferguson from Save the Bay, who said that she is seeing degraded conditions around the state more frequently, and that this is a result of sea level rise.

“Marshes, historically, have been able to keep up with sea level by building up elevation, or accretion,” she said. “But now they are not, due to the increased rate of sea level rise.”

As the sea encroaches upon salt marshes, marshes are either migrating landward or drowning in place because they run into barriers such as structures or elevation change. The model can predict where marshes will go, or how they will likely migrate, but there are limitations on the models, such as the certainty of sea level rise projections, ground conditions, and coastal changes from storm events, said Kevin Ruddock of The Nature Conservancy. But the maps produced from the SLAMM are helping to lay the groundwork for restoration efforts and new policies and management strategies that can help communities, said Boyd.

Caitlin Chaffee, CRMC, talks about how standing ponds can hurt surrounding marsh vegetation if it can't be drained.

Caitlin Chaffee, CRMC, talks about how standing ponds can hurt surrounding marsh vegetation if it can’t be drained. Narrow River.

Towns expected to suffer the most salt marsh loss are Narragansett, Barrington, Bristol, Portsmouth, and Charlestown. Restoration efforts are underway utilizing the $7.02 million post-Sandy funds awarded by U.S. Department of the Interior through National Fish and Wildlife Foundation to help restore marshes, wetlands, and beaches; rebuild shorelines; and research storm surge mitigation. Some of these efforts include dredging and sediment transport to build marsh elevation and building runnels (narrow channels) to drain standing water off of the marsh, said Caitlin Chaffee of CRMC. Other efforts lead by TNC include “Living Shorelines.” This project places natural materials such as coir logs made from coconut fibers or bagged oyster shells to counter erosion along the marsh edge. +Read More


Listen to audio presentations by James Boyd, RI Coastal Resources Management Council; Wenley Ferguson, Save the Bay; Kevin Ruddock, The Nature Conservancy: and Caitlin Chaffee, RI Coastal Resources Management Council

– Meredith Haas | Rhode Island Sea Grant Research Communications Specialist