| description:
|
To project future marsh change under projected sea level rise (SLR), a marsh change data product provided by the NOAA Office for Coastal Management that was developed for the US Digital Coast Sea Level Rise Viewer (https://coast.noaa.gov/digitalcoast/tools/slr.html) was employed. The NOAA marsh change product, based on the Sea Level Affecting Marshes Model (SLAMM), identifies coastal marsh areas that may be vulnerable for conversion to either non-vegetated or open water. Three scenarios of sea level rise (1’, 2’ and 3’) out to the Year 2050 were examined. Based on the consensus SLR estimates determined for New Jersey (Lathrop, Kopp and Kaplan, 2014), 2.5’, 5 and 7’ Year 2100 SLR scenarios were employed. These levels were then scaled to the Year 2050, equating to 1’, 2’ and 3’ of SLR (at 2050) using the NOAA guidance 2017 document. The NOAA implementation employs a “modified bathtub” approach that incorporates local and regional tidal variation of mean higher high water (MHHW) (NOAA, 2017). Adjacent upland forests and freshwater swamps that may affected by rising sea levels and predicted to convert to marsh are also identified (referred to here as marsh retreat zones). Using geospatial analysis software, those adjacent upland/wetland areas that are directly contiguous to salt marsh were mapped and labeled as unimpeded marsh retreat zones. Areas where future tidal marsh retreat are blocked by developed uplands, other coastal protection structures or roads were mapped and labeled as impeded marsh retreat zones. Trees and shrubs growing in these upland forests and freshwater swamps presently occupying these identified marsh retreat zones are highly vulnerable to increased physiological stress and dieback as sea levels continue to rise.
|