Description: Marsh shorelines and bayshore beaches are subject to the erosive action of storm and boat wake-driven waves. Fagherazzi (2013 The ephemeral life of a salt marsh. Geology, 41, 943–944) suggested that while coastal marshes are relatively stable in the vertical direction if enough sediment is available, they are inherently unstable along the horizontal direction due to lateral erosion. This Shoreline Erosion dataset was generated by Rutgers Center for Remote Sensing & Spatial Analysis. Areas of coastal marsh lost to shoreline erosion were determined by comparing the shoreline position changes between a baseline year during the 1970s and 2010. The calculated annual erosion rate (in feet/year) for each marsh shoreline cell was then projected inland to the year 2050 to map areas vulnerable to future shoreline erosion.
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Additional Information
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The baseline marsh/back bay shoreline was defined by the 1977 New Jersey Tidelands Claimed line. The NJDEP Tidelands claims map (http://www.nj.gov/dep/gis/tidelandsshp.html) depicts areas now or formerly flowed at or below mean high tide as of 1977. The “Claimed” and “Unclaimed” tidelands were extracted and the individual map tile boundaries dissolved. The tidelands data were rasterized at a grid size of 10 m to match the New Jersey DEM (provided by NOAA CSC) spatial extent. <br><br>
To depict the shoreline at 2010, the Mean Tide Level (MTL) water surface layer from NOAA CSC V-Datum water surface layers was differenced against the NOAA CSC NJ DEM (at 10 m grid size). The Tidelands Claimed layer was buffered inland. The resulting buffer distance file was overlaid with the NJ_water_mask to determine those areas where the shoreline eroded (Tidelands Buffer and Water) vs. areas that have accreted (Not Tidelands and Not water) vs. No Change. Due to the 2010 baseline for the V-Datum MTL data and the 1977 year for the Tidelands data, there was a 33 year difference in time. Given a 10 m grid cell width, this equates to approximately 1 foot for year (10 m = approx. 33 feet; 33 ft/33 yr = 1 ft/yr). The calculated annual erosion rate for each shoreline cell was then projected inland to the year 2050 to map areas vulnerable to future shoreline erosion.
Description: This map layer depicts the frequency of Coastal Ice Cover. The USGS EarthExplorer Landsat 5-7-8 archive was examined for winter dates with substantial presence of ice on New Jersey’s coastal waters. The objective was to map locations were ice forms and builds up during sufficiently cold winter periods. There were many winters were little if any ice formed on coastal waters or at least was not visible on available Landsat imagery dates either due to the fact that no ice was present or cloud cover obscured visual interpretation. Five images were selected to represent 5 different years. Landsat 5 and 7 Thematic Mapper Level 1 imagery downloaded from USGS EarthExplorer site http://earthexplorer.usgs.gov/. Following images were downloaded for Path/Row 14-31-33:
Landsat 7 ETM January 29, 2000
Landsat 5 TM February 1, 2004
Landsat 5 TM February 9, 2007
Landsat 5 TM January 29, 2009 Landsat 5 TM January 3, 2011.
A normalized snow index (NDSI) was computed [(Band 2 - Band 5)/(Band 5 + Band 2)] using the Level 1 imagery. The imagery data were taken “as is” without any additional processing (i.e. atmospheric or radiometric corrections). The NSDI data were thresholded using a digital number value of 210 to generate an “ice cover” layer (i.e., if NSDI > 210 ice). The resulting ice cover for the 5 dates were composited using a rule where Output = 5, when all 5 dates were classified as ice cover; Output = 4, when 4 out of 5 dates were ice cover. It is estimated based on experience and anecdotal information that the ice thickness of those areas classified as ice cover were at least 2-3” inches thick. Areas of higher frequency ice cover were equated with greater ice thickness (inches). The resulting composite data were further qualitatively classed as: Value 0 = No ice cover
1 = Low Ice cover (i.e. ice cover on 1 of 5 dates) (0-2" thick)
2 = Moderate ice cover (2.1-4" thick)
3 = High ice cover (4.1-6 " thick)
4 = Highest ice cover (> 6" thick)
Description: This map layer depicts the Shoreline Slope in units of percent slope. This map layer was generated by the Rutgers University center for Remote Sensing and Spatial Analysis.
The US Geological survey-provided a seamless topographic-bathymetric digital elevation model (at 1 m grid cell resolution) was used to derive slope (%) in ERDAS Imagine. Shoreline slope was defined within the intertidal zone between MHHW (Mean Higher High Water) and MLLW (Mean Lower Low Water).
Description: This map layer depicts the Nearshore Slope in units of percent slope. This map layer was generated by the Rutgers University center for Remote Sensing & Spatial Analysis.
The US Geological survey-provided a seamless topographic-bathymetric digital elevation model (at 1 m grid cell resolution) was used to derive slope (%) in ERDAS Imagine. Nearshore slope was defined as the slope of the subtidal water (below MLLW) out to a depth of 5’. The nearshore slope was then projected to the MTL shoreline using ESRI ArcMap function EXPAND.
Description: This map layer depicts the Tidal Range (i.e., vertical difference in height between high and low tide) in units of feet. This map layer was generated by the Rutgers University Center for Remote Sensing and Spatial Analysis.
Tidal water surface layers, generated using the software program V-DATUM, were provided by the NOAA Coastal Services Center (CSC, NOAA CSC contact was William Brooks) for the coastal waters of New Jersey. Tidal range was defined as the vertical difference in water surface height between the MHHW (mean higher high water) layer and the MLLW (mean lower low water) (i.e. MHHW- MLLW). The data were rasterized to 10 m grid cells to match the spatial extent of the NOAA CSC New Jersey DEM. The original tidal range heights were given in meters but converted to feet for inclusion in the Restoration Explorer app.
Description: Sampling site locations and water quality samples were downloaded (as of 2015) from the National Water Quality Monitoring Council's Water Quality Portal (WQP), located at https://www.waterqualitydata.us. Average salinity values (in ppt) were calculated for each sample location. A continuous map was then generated using the ArcGIS Inverse Distance Weighting interpolation tool. <br><br>
Additional information
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Sampling site point data were imported into ESRI ArcGIS using Add XY Data, using GCS_North_American_1983 (lat/Long) as the coordinate system. The points were then projected into NAD 1983 New Jersey State Plane FIPS 2900 coordinate system. Min/Max/Average salinity values (in ppt) were calculated for the field ResultMeasureValue and then summarized for each sample location using the Summary Statistics tool. <br><br>
Points that had values (NOT NULL) were then used as input into the IDW tool, using the appropriate field (Min/Max/Average) as the Z value. The cell resolution was set to 250 feet. After some preliminary review of the outputs, certain outlier sample points were dropped as input into the IDW tool, and the final IDW surfaces were created. The output surfaces were then masked by land boundaries up to the head of tide. The final step was to project the surfaces into the Web Mercator projection, using a 75 meter output cell size with cubic convolution, in order to be displayed as web maps. The salinity units are ppt (parts per thousand).
Description: This map layer depicts the Mean Wave Height in units of feet. This map layer was generated by the Rutgers University Center for Remote Sensing and Spatial Analysis.
Wave data was provided by Natural Capital Project (http://www.naturalcapitalproject.org/). The data for any individual model point was averaged across the various compass point directions. Due to the spatial displacement of the rather coarse spatial scale individual model points and the finer scale MTL shoreline, the NatCap data was resampled to match the finer scale shoreline data. The NatCap points were interpolated using the ArcGIS IDW (inverse distance weighted interpolation) algorithm with (1 neighbor selected, power = 1 and 1500 m search distance). A barrier poly line was used to help separate NatCap points in the ocean influencing interpolation on the bayside margin. The above approach basically is similar to a nearest neighbor resampling to assign the closest NatCap point value to each MTL shoreline grid cell. The original wave heights were given in meters but converted to feet for inclusion in the Restoration Explorer app.
The engineering guidelines suggest the Ecologically-Enhanced Revetment and Breakwater techniques can handle higher wave energies. These techniques were scored as NA for lower wave conditions, though they can handle these lower wave heights. In lower wave energy conditions, one might opt for some of the other techniques that might have greater ecological uplift such as the Marsh Sill or Living Reef.