DEEP: Sea Level Rise Visualization Tool

Coastal Hazards Mapping Tool

Important Background Information
The Connecticut Coastal Hazards Viewer is an online mapping tool designed to allow users access to several pertinent suites of data for coastal Connecticut. Presented here are data representing sea level rise, high-resolution coastal elevation, hurricane storm surge, coastal erosion, and environmental observations such as tides, water quality, waves and currents.

The data presented here are intended for planning and/or illustrative purposes only and should not be used for determining actual jurisdictional boundaries, making regulatory decisions, developing engineering analyses/designs, etc.
These maps and the data contained in them are not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user. Reasonable attempts have been made to ensure that this data and documentation is accurate and reliable; however neither the Connecticut Department of Energy and Environmental Protection, nor its partners assumes 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. NOAA, The Connecticut Department of Energy and Environmental Protection, and the University Of Connecticut Department Of Marine Sciences make no warranty, expressed or implied, as to the accuracy, completeness, or utility of this information, nor does the fact of distribution constitute a warranty.

Sea Level Rise Visualization Data
Currently the visualization data depicts estimates of inundation due to sea level rise across all Connecticut towns with direct frontage on Long Island Sound (and Fisher's Island Sound). Coastal communities can use these products to see various inundation scenarios and begin thinking about how to prepare for them.

The scenarios shown here are based on recent LiDAR elevation data collected in 2004 and 2006 by FEMA and processed by the CT Dept of Environmental Protection. Each reflects what inundation might look like at one of two tide levels: mean high water (MHW) or the "average monthly maximum water level" (AMM). AMM an attempt to quantify the maximum extent of tidally influenced water levels. This value is based on historic observed tidal data values that were used to define a generalized formulation for AMM values for any area of the CT coastline.

The scenarios are taken from both global and regional estimates, each associated with a particular time frame. In doing so, they present a way to look at short, medium, and long-term potential effects. The table below describes the sea level rise value, its source, and applicable time frame.

Sea Level Rise (in / ft)

Approximate Relation to Scientific Data

Planning Horizon

6 in / 0.5 ft

Average 2004 Environmental Defense Hi/Low emissions


12 in / 1.0 ft

Average 2004 Environmental Defense Hi/Low emissions


18 in / 1.5ft

2004 Environmental Defense High Emissions


24 in / 2.0 ft

2007 IPCC High Emissions


36 in / 3.0 ft

2004 Environmental Defense High Emissions


60 in / 5.0 ft

n/a gap filler


79 in / 6.6 ft

Pfeffer et al 2008


In addition to depicting the extent of inundation, each layer also provides the depth (in units relative to NAVD88) between the inundation level and the ground as depicted by the LiDAR data. Thus, identifying any location will provide a sense of "how deep" the water may be. Each location in the inundation layers generalizes a 3ft by 3ft area on the ground.

Coastal Digital Elevation Model
The 2006 Coastal CT 3ft Digital Elevation Model (DEM) can be used to identify the elevation of the ground at any given point within Connecticut's coastal boundary and provide a graphic representation of bare-earth topography. The DEM is a raster layer of high-resolution ground elevation data for Connecticut's coastal towns. The elevation data spans the approximate extent of the 100-year flood zone, as defined by the Federal Emergency Management Agency (FEMA.) The layer is based on information from bare-earth LiDAR elevation data collected and compiled during December, 2006 (all towns without frontage on the Connecticut River) and Spring/Summer, 2004 (towns on the Connecticut River). Each cell in the raster has a single elevation value, representing the height of the ground in inches NAVD88. Each cell represents a 3 foot by 3 foot area on the ground. The original LiDAR data were collected to support Digital Flood Insurance Rate Map (DFIRM) Modernization and conformed to FEMA's LiDAR collection specifications.

Hurricane Surge Inundation Data
This information includes Hurricane Surge Inundation areas for category 1 through 4 hurricanes striking the coast of Connecticut with a peak hurricane surge arriving at high mean water.

Erosion Susceptibility Data
Connecticut Erosion Susceptibility a 1:24,000-scale, polygon feature-based layer that was developed as a predictive tool to show areas most susceptible to terrace escarpment type erosion.

LIS Environmental Observations Data
The LIS Environmental Observations layer provides the location of monitoring devices and access to the data collected by the LIS Integrated Coastal Observing System (LISICOS), the National Oceanic & Atmospheric Administration (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS), and the US Army Corps of Engineers New England District (ACOE-NED).

Proceed to the Coastal Hazards Mapping Tool

Content Last Updated January 3, 2012