Sea Level Affecting Marshes Modeling

Using the Sea Level Affecting Marshes Model (SLAMM) to Assess Impacts of Sea-Level Rise

What is SLAMM?

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

What is a SLAMM viewer?

A web-based mapping application used to present the Long Island Sound SLAMM project results.

How can SLAMM inform decision making?

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.

Where can I find out about Sea Level Rise projections for Connecticut’s largest marshes as well as coastal roads?

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.

How will the SLAMM data help NY municipalities plan for changing coastlines?

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.

What if I am interested in researching an area that’s not included in the Connecticut viewer or the viewer being developed for New York?

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 (CT DEEP) 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.

Click the right arrow to view SLAMM's sea level rise scenario for Hammonasset Beach State Park (Clinton Harbor) in CT.
The model projects regularly-flooded (low) marsh and tidal mudflats displacing irregularly-flooded (high) marsh.
Clinton Harbor area marshes in 2010. The different colors depict different land cover types.
Clinton Harbor area marshes in 2055. The land cover types are changing.
Clinton Harbor area marshes in 2100. The eastern areas of the marsh are drowning, resulting in marshes changing to mudflats.
Likelihood of coastal marsh in 2100. SLAMM provides a guide on how likely an area might be a coastal marsh. Darker areas are more likely.
Get started on your own research by reading "How Does Slamm Work" manuals (see link below).

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.

Who is working on the SLAMM project for Long Island Sound?

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.


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