Sea Level Rise Effects on Roads & Marshes


Visit the following topics for information about the project.

How SLAMM Works | Limitations | Sea Level Rise and Coastal Marshes | Sea Level Rise and Coastal Roads | Soils Suitable for Marsh Migration | Data Layer Information | Aerial Photos


Study Area

Marsh Study Area - 21 marshes

This study focused on 21 of Connecticut's largest tidal marshes. There are many more marshes and wetlands that were included in the SLAMM results but not included in this study. Heads-up editing eliminated areas in the SLAMM output layers that were determined to not be a part of any of the 21 marsh complexes. Ancillary data such as the DEEP Critical Habitat layer and aerial imagery informed these decisions along with expert opinion.

Roads Study Area

SLAMM reports projected flooding for roads with surface elevations at or below the elevation of the 1 percent chance (or 100-year recurrence interval) coastal still water flood adjusted for a sea level rise rate of approximately 4 feet by 2100 from the base year of 2002. This SLR rate is depicted by the orange line (High-Medium Projection) in the following figure.  Still water elevation (SWEL) is defined by Federal Emergency Management Agency’s most recent flood insurance studies as the elevation of water due the effects of astronomic tides and storm surge on the water surface.  


Scenarios based upon New York City Panel on Climate Change, 2013: Climate Risk Information 2013: Observations, Climate Change Projections, and Maps. Prepared for use by the City of New York Special Initiative on Rebuilding and Resiliency, New York, New York. Mayor’s Office of Long-Term Planning & Sustainability.