SLAMM (Sea Level Affecting Marshes Model) is a tool that can be used to project how salt marshes may respond to sea-level rise. SLAMM predicts long term shoreline and habitat class changes as a function of land elevation, tide range, sea-level rise, and other environmental factors.
View a Slideshow Describing the Sea-Level Rise Impacts Predicted to the East River Marsh
Saltmarsh vegetation thrives in the ebb and flow of the tides, but they are likely to be severely impacted by the increases in flooding anticipated with sea-level rise in the 21st century. In order to plan for the impact, Connecticut and New York are using the Sea Level Affecting Marshes Model, or SLAMM, to project the extent of tidal wetland habitat under different sea-level rise scenarios. (The photo shows the Hammonasset Beach State Park marsh during high tide. Credit: Alyssa Borowske.)
The Connecticut Department of Energy and Environmental Protection is using SLAMM to assess 21 of its largest marshes, including the East River Marsh in Guilford and Madison shown here. SLAMM is also being used to assess the impact of sea-level rise on coastal roads. Credit: Connecticut ECO website.
In 2010, a majority of the East River Marsh consisted of vegetation in the high and low marsh zones. Source: UConn Center for Land Use and Environmental Research (CLEAR) and the Sea Level Rise Effects on Roads and Large Marshes project.
By 2055, under a scenario that projects a sea level rise of approximately 2 feet*, the wetland composition is shifting from high marsh to low marsh, and low marsh is shifting to tidal flats. Source: Connecticut Sea Level Rise Effects on Roads and Large Marshes project.
*Two feet of sea-level rise by 2055 is considered a high sea-level rise scenario. Changes in wetland composition and wetlands loss are also projected for low and intermediate scenarios.
Under the same high sea level rise scenario with approximately six feet of sea-level rise by 2100, more frequent flooding of the marsh surface is expected to convert much of the marsh to tidal flats and open water. Source: Connecticut Sea Level Rise Effects on Roads and Large Marshes project.
Sea-level rise is already affecting several several species of marsh birds. Nests of saltmarsh sparrows, seaside sparrows, willets, and clapper rails are all vulnerable to tidal flooding on the especially high tides that happen around the full or new moon. Saltmarsh sparrows and willets solve this problem by nesting in parts of the marsh that are least likely to be flooded. Seaside sparrows tend to nest in taller vegetation, where they build their nests higher off the ground. And, clapper rails have specialized behaviors that help them cope with flooded nests. Nonetheless, as marshes get wetter and convert from one type to another, all of these species become more vulnerable to losing their eggs and chicks to the tide. (The photo shows saltmarsh sparrow chicks in a flooded nest during the high spring tide when the marshes are completely flooded. Credit: Jeanna Mielcarek/UConn SHARP.)
Besides being valuable wildlife habitat, tidal wetlands provide a variety of other “ecosystem benefits,” including buffering developed upland areas from potentially damaging storm surge, filtering pollutants, and capturing carbon dioxide. Resource managers are looking at the information from the SLAMM project to see how wetlands can be protected and for the possibility that upland areas might be able to accommodate marsh migration. (The photo shows high marsh habitat at Mamacoke Island, Waterford, CT. Credit: Connecticut College Arboretum.)
At the East River Marsh, which includes Audubon Connecticut’s 111-acre Salt Meadows Sanctuary, CTDEEP is working with Audubon to develop an East River March Resilience Conservation Strategy. CTDEEP also has prepared a fact sheet providing details on the projected sea-level rise changes to the marsh and the initial strategy to respond to the threat. Credit: Audubon Connecticut.
The Connecticut SLAMM viewer, described on this page, will let you see how 21 of Connecticut’s largest marshes will respond to sea-level rise, including the East River Marsh. You can find it on the CT Eco website.
A web-based mapping application used to present the Long Island Sound SLAMM project results.
SLAMM data and maps are one of many resources available to investigate how Long Island Sound’s coastline may respond to sea-level rise (SLR). The data show how the coastal land cover can change over time under alternative SLR scenarios. These results can help identify adaptation strategies, such as land acquisition, marsh restoration, and infrastructure management. Click here to learn more about what SLAMM can do.
In an effort to help Connecticut state agencies, municipal land-use officials, and the general public visualize possible responses to sea-level rise, an online geospatial data viewer, developed by the UConn Center for Land Use Education and Research (CLEAR), describes the effects of sea-level rise on Connecticut’s coastal roads and 21 of the state’s largest marshes. The Sea Level Rise Effects on Roads and Large Marshes Viewer provides a screening-level tool to identify areas potentially well-suited to accommodate the upland migration of Connecticut’s largest coastal marshes, and the vulnerability of coastal area roads to regular tidal and episodic coastal storm flooding with sea-level rise.
Information on the Connecticut SLAMM Viewer web pages is available on the CT ECO website, including important information on the intended uses and limitations of the data presented in the viewer. It also includes a web page describing how SLAMM can be used to assess potential coastal road flooding exacerbated by sea-level rise. An archived webinar presentation from Oct. 16, 2019, explaining how to use the Viewer is available on the UConn CLEAR website.
NYSDEC, along with NEIWPCC, has hired Warren Pinnacle Consulting Inc. (WPC) to work on creating “Developing Conservation Plans for New York’s Long Island Sound Marsh Complexes project. When completed it will provide valuable information to Long Island Sound municipalities and/or marsh conservation groups to develop marsh conservation plans and increase coastal resiliency. Specifically, WPC will use the Sea Level Affecting Marshes Model (SLAMM) projection analysis to identify existing and future high-ecological-value coastal marshes along Long Island Sound, develop a stakeholder interactive viewer that intersects marsh ecological values and tax parcel information, present data-analysis results and determine community interest at regional workshops, assist in developing marsh conservation plans, and participate in community workshops to present draft marsh conservation plans and prepare a final plan.
The original LIS SLAMM viewer provides modeling data results for any Long Island Sound parcel and is available through three freely accessible web-based map viewers. Two examine selected results at 2055 and 2100; the third provides access to all of the results. The buttons below will open the viewers.
We recommend that first-time users should read manuals prepared by the Connecticut Department of Energy and Environmental Protection (CTDEEP) and the Long Island Sound Study to understand what the viewers are showing and how to use them. The manuals are available on the LISS website.
We have also put together three tables that show statewide and Soundwide projections. Click here for the web page to view the tables as well as finding links to raw data.
The slide show above shows an example of a sea level projection from the original SLAMM viewer. You can also watch a You Tube video to see a summary of some of the SLAMM pages on the original Long Island Sound Study website.
SLAMM’s application to Long Island Sound was conducted by Warren Pinnacle Consulting, whose programming and application of the model has been used in every US coastal state and national wildlife refuge. The project was commissioned by the federal and state agencies listed below who helped collect and review much of the model’s input data in cooperation with leading academic and other salt marsh ecology experts. The project partners are working with their consultant to improve the data used in SLAMM and are analyzing, and distributing the current LIS SLAMM results for use by all.
Salt marshes are dynamic ecosystems that provide significant ecological and economic value. They are also among the most susceptible ecosystems to climate change, especially sea level rise (SLR). See graphic.