Connecticut Sea Level Rise and Storm Surge Viewer

This dataset shows different flood maps with sea-level rise projections (1 foot and 20 inches), above a Mean Higher High Water (MHHW) along the Connecticut coastline and the adjacent inland. CIRCA research recommends that planning anticipates sea level will be 20 inches higher than the national tidal datum in Long Island Sound by 2050. CIRCA’s report on Connecticut sea level rise provided the basis for projections in Bill S.B. 7, which was introduced into the 2018 legislative session and was enacted into law as Public Act 18-82.

To view the data, zoom in on the map to your area of interest. Use the Layers menu widget at the bottom of the map window to select data to display. Different projections of sea-level rise/storm surge scenarios will activate automatically at different scales. FEMA’s Limit of Moderate Wave Action boundary is also shown on this viewer as a continuous red line. The coastal AE Zone is depicted on current effective flood insurance rate maps (FIRMs) with the landward limit of the zone labeled “Limit of Moderate Wave Action”. Any area seaward of the red LiMWA line is either coastal AE or VE zone and must meet new construction requirements outlined in the updated state building code.


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Data Description and Usage

Two different sets of data are presented in the viewer. The NOAA indicated ones are the modeled tidal water surface that has been created using VDatum (NOAA) and 2016 LiDAR topographic data. Using the same model and NOAA Long Island Sound tide gauge data, CIRCA also estimated the 100-year flood event levels above MHHW. High probability areas of inundation are color shaded as well as low-lying areas, which are all shaded yellow. These low-lying areas need further evaluation due to the hydrologic complexity created by flood control structures, bridges, and culverts.

The second set of data, FVCOM, is the modeled storm surge water levels using coupled coastal circulation and wave model (FVCOM-SWAVE, finite-volume coastal ocean model with the version of the Simulating Wave Nearshore) to hindcast the 44 highest storms between 1950-2018. The floodwater elevation for the different annual exceedance probabilities is calculated empirically using a Poisson-GPD fit. The return period of the storm events presented is 10, 30, 100, and 500-year with 10%, 3.33%, 1%, and 0.2% annual exceedance probability storms, respectively. The anticipated sea level of 20 inches by 2050 is also added to the different flood scenarios. The data is projected to the land using 2016 LiDAR topographic data.


This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user. Attempts have been made to ensure that this data or documentation is accurate and reliable; The University of Connecticut, nor the Department of Marine Sciences, does not assume liability for any damages caused by inaccuracies in this data or documentation, or as a result of the failure of the data or software to function in a particular manner. The University of Connecticut, nor the Department of Marine Sciences, makes no warranty, expressed or implied, as to the accuracy, completeness, or utility of this information, nor does the fact of distribution constitute a warranty.