Northeast Region Marsh Migration is one of a suite of products from the Nature’s Network project. Based on sea level rise (SLR) analysis by NOAA, this dataset depicts potential marsh migration zones at various sea level rise scenarios from 0-6’. Identification of suitable uplands adjacent to tidal wetlands is based on topography, habitat type, land use, and development, and can be used for facilitating marsh migration through land protection and/or management. The NOAA Coastal Change Analysis Program (CCAP) mapped the initial (current) distribution of potential marshes and and other coastal land cover types. The Detailed Method for Mapping Sea Level Rise Marsh Migration provides the full methodology for the data used to create the aggregated Marsh Migration layer in Nature’s Network, and describes the initial condition as follows:

“Wetland data portrayed as the initial condition within the viewer is derived from NOAA’s Coastal Change Analysis Program (C-CAP). C-CAP produces a nationally standardized database of land cover and land change information for the coastal regions of the U.S. These products provide inventories of coastal intertidal areas, wetlands, and adjacent uplands with the goal of monitoring these habitats by updating the land cover maps every five years. Data used in this analysis reflect conditions as they existed when mapped in the 2005 to 2006 timeframe. For the purposes of this analysis, the full C-CAP classification scheme has been simplified, removing detail in upland features to place emphasis on wetland areas. “

For Nature’s Network, Marsh migration areas were mapped using data available on the sea level rise viewer in combination with elevation and tidal range data to examine the extent of undeveloped upland available for migration and predict future marsh habitat in one foot increments up to 6ft. The sea level rise viewer provides access to predicted SLR in 1 foot increments for coastal states. For Nature’s Network, the initial condition and each increment of SLR data were aggregated for the Northeast states, providing a seamless layer depicting the range of SLR scenarios, and the potential marsh migration areas associated with each SLR amount.

A number of additional datasets that augment or complement Marsh Migration, are available in the Nature’s Network gallery on Data Basin.

Known Issues and Uncertainties

As with any project carried out across such a large area, this product is subject to limitations. The results by themselves are not a prescription for on-the-ground action; users are encouraged to verify, with field visits and site-specific knowledge, the value of any areas identified in the project. General constraints and uncertainties include the following:

• The marsh migration data are based on predictions about future sea levels, climate, and development, and are therefore subject to high levels of uncertainty;

• Although Nature’s Network is intended to be based on the best available science, alternative models of SLR and climate change may not agree with the model inputs selected for this analysis;

• The Marsh Migration data are intended to provide one source of information to be be used in conjunction with local information, expert input, and alternative scientific assessments to inform marsh conservation and coastal adaptation to sea level rise; the data should not be interpreted as providing a definitive recommendation

From Detailed Method for Mapping Sea Level Rise Marsh Migration:

• These data are for planning, educational, and awareness purposes only and should not be used for site-specific analysis, navigation, or permitting.

• The mapping does not incorporate future changes in coastal geomorphology and assumes present conditions will persist, which will not be the case.

• The digital elevation model (DEM) used to map SLR does not incorporate a detailed pipe network analysis, or engineering grade hydrologic analysis (for example, culverts and ditches may not be incorporated resulting in incorrectly mapped areas).

• The data in the map do not consider many natural processes, such as freshwater influences to salinity, subsidence, sediment erosion dynamics, or coastal storm impacts.