Geospatial data in support of structured decision making for Fire Island National Seashore, New York

All process steps were performed by either Kate Ackerman or Brian Andrews (contact information in this process step and the next), using ArcGIS Pro (ver.3.2.1). For simple operations the name of the geoprocessing tool used is given in capital letters; for complex operations, the name of the geoprocessing tool used is given in capital letters and any critical parameters used are given in parentheses, separated by a semicolon, immediately after the tool name. The input and output file names are provided in [square brackets] when necessary. Units for length and area calculations are meters (m) and square meters (m2) unless otherwise stated.

Export [mu_lifespan_NY.shp] to create a new shapefile [FIIS_SDM_Metrics.shp], keeping only the marsh units that are in the FIIS park boundary, and the fields that are needed for the SDM performance metrics: the marsh unit unique identification number (FID_CMU), the total area of the marsh unit (ATOT_M2), the area of the vegetated portion of the marsh unit (AVEG_M2), the lifespan under global mean sea-level rise of 0.5m and 1.0m by 2100 (GMSL05, GMSL10), the unvegetated to vegetated marsh ratio (UVVR), and the flag denoting anomalous marsh units (FLG). Project the shapefile from WGS 1984 Web Mercator Auxiliary Sphere to NAD 1983 (2011) UTM 18N.

Create attribute "Zstar" to calculate elevation relative to tidal range. Calculate the mean relative wetland elevation value relative to tidal range (Zstar (Z*)) within each marsh unit (FID_CMU). Zstar, the relative tidal elevation value, is a metric that normalizes elevation to the tidal amplitude at mean high water. Z* = (orthometric elevation - mean sea level) / (mean high water - mean sea level).
Run ZONAL STATISTICS AS TABLE (feature zone data: [FIIS_SDM_Metrics.shp], zone field: FID_CMU, value raster: [relative_tidal_elevation.tif], statistics type= Mean) to calculate the average Z* value for each marsh unit. In [FIIS_SDM_Metrics.shp], add new attribute "Zstar" (Double) to attribute table and populate with results of zonal statistics (MEAN) by joining via the "FID_CMU" field. Assign a value of -9999 for marsh units that do not have Zstar data.

Create attribute “AMIG_M2” to assess the marsh migration potential of each marsh unit, calculated in terms of available migration area, under 2 feet of local sea-level rise, for each marsh unit.
This process step followed the methodology detailed in "Chesapeake Bay marsh migration potential under sea-level rise" (Defne and others, 2025), and used these input datasets for FIIS: (1) Marsh migration datasets for New York [marsh_migration.tif] (2) NHD datasets for HUC 0203 [NHDPlus Catchment].
The migration space is based on the NOAA marsh migration predictions under 2 feet of local sea-level rise and divided into smaller parcels by using the National Hydrography Dataset Plus (NHD Plus) catchments. The marsh migration space is then distributed to the marsh units.

Create attribute "WavePwr" to assign a wave power value to each marsh unit. Create "Wake_Norm" to assess the wake exposure of each marsh unit.
Wave power: 1. Create a raster surface dataset from the feature points, using inverse distance weighting (IDW). The parameters used in the IDW tool are conservative so that additional variability is not added to the wave power input dataset. a) Remove data points in the ocean as well as points with a value of zero on the beach. b) IDW (Input point features: [WavePower.shp]; Output Cell Size=0.0001 degree; Power=2; Search Radius=Variable; Number of Points=1) to obtain [WavePower_IDW.tif].
2. Clip the raster to marsh boundaries. A buffer zone is created around the marsh boundaries to facilitate alternative interpolation and clipping options in future studies. a) Create 300 m buffer around the marsh units polygons to create a clipping mask [mu_buff300m.shp]. BUFFER (Side type= Full; Method= Geodesic; Dissolve type= All). b) CLIP the raster [WavePower_IDW.tif] with the clipping mask [mu_buff300m.shp] to obtain [WavePower_IDW_clip.tif]. c) EXTRACT BY MASK (Input raster= [WavePower_IDW_clip.tif]; Mask=[FIIS_SDM_Metrics.shp]) to obtain [WavePower_IDW_MU.tif].
3. Calculate mean wave power value for each marsh unit. a) PROJECT (Output coordinate system=GCS WGS 1984) [FIIS_SDM_Metrics.shp] to [mu_diss_WGS84]. b) ZONAL STATISTICS AS TABLE (Feature Zone Data=[mu_diss_WGS84.shp]; zone field=FID_CMU; Value Raster=[WavePower_IDW_MU.tif]; Output Table=[wp]; Statistics type=MEAN). c) JOIN FIELD (Input table=[FIIS_SDM_Metrics.shp]; Input join field=FID_CMU; Join Table=[wp]; Output join field=FID_CMU; Join Field= MEAN). Change “MEAN” to “WavePwr.”
Wake Exposure: 1. Determine the number of boats that are within 500 m of each marsh unit. SUMMARIZE NEARBY (Input=[FIIS_SDM_Metrics.shp], Input summary features= [Vessel_Location], Output= [MU_Vessel_summary], distance measurement: straight line; distance: 500 meters; keep polygons with no points).
2. Calculate "Wake_Norm" to normalize the point counts to a value between 0 and 1. Wake_Norm= (Point_count - minimum value)/ (Maximum value - minimum value). Join "Wake_Norm" to [FIIS_SDM_Metrics.shp].

Create attribute “NWIclass” to calculate the number of different NWI marsh subclass types found within a marsh unit.
(1) Create a shapefile of the NWI classes that are used for the marsh unit analysis. From [NWI.shp] SELECT (ATTRIBUTE LIKE 'E2%EM%' OR ATTRIBUTE LIKE 'E2AB3%' OR ATTRIBUTE LIKE 'E2EM%' OR ATTRIBUTE LIKE 'E2SS%' OR ATTRIBUTE LIKE 'E2US4%'), EXPORT features to create [NWI_exclusive_select.shp]. Add an additional field that captures the first 5 digits of the NWI attribute field (no modifiers are retained).
(2) PAIRWISE INTERSECT the NWI [NWI_exclusive_select.shp] and the marsh units [FIIS_SDM_Metrics.shp] to assign NWI classes to each marsh unit. DISSOLVE the resulting shapefile (Dissolve field: FID_CMU, Concatenate) to obtain a list of all NWI classes found in each marsh unit. Calculate the number of different NWI subclasses found in each marsh unit.

Create attribute "Ditchkmkm2" to calculate the density of ditches for each marsh unit. It is calculated by summing the linear length of ditches (km) divided by the area of each marsh unit (square kilometers). The final value for each marsh unit is ditching intensity (linear kilometers of ditch per square kilometer of marsh unit area).
PAIRWISE INTERSECT the ditches [NortheastUSDitches_Polyline.shp] and marsh units [FIIS_SDM_Metrics.shp] then SUMMARIZE ATTRIBUTES by FID_CMU to get total length of ditches in each marsh unit. Calculate the ditch density (km/km2): total length of ditches (km) in a marsh, divided by the total marsh unit area (km2).

Create attribute "BioDiv" that provides information on the biodiversity of the marsh unit, which is the summation of the "SALS_P" (whether the marsh unit intersects a “priority marsh” for Saltmarsh Sparrow) and the "SAV" (whether the marsh unit is within 100m of seagrass beds) attributes.
SALS_P: SELECT BY LOCATION (intersect) [ACJV_SALS_Priority_Marshes] and [FIIS_SDM_Metrics.shp] to identify marsh units that intersect priority habitat for Saltmarsh Sparrow. If they intersect, the marsh unit is assigned a value of 1 for the “SALS_P” attribute.
SAV: SELECT BY LOCATION (intersect, 100 m) [SAV.shp] and [FIIS_SDM_Metrics.shp] to identify marsh units that have seagrass within 100 m of the marsh unit. If seagrass beds are within 100 m of the marsh unit, the marsh unit is assigned a value of 1 for the “SAV” attribute.
BioDiv: The “BioDiv” attribute is the sum of the “SALS_P” and “SAV” attributes.

Create attribute “Quantl” to compare the size of marsh units across the Park. Based on the total marsh unit area, the marsh units are binned into 5 equal area bins. Each marsh unit is placed into a bin based on its size (bin 1 contains the smallest marsh units; bin 5 contains the largest marsh units).
Calculate the total area of all marsh units, sort marsh units by size, divide the dataset into five approximately equal parts based on area. The smallest marsh units will have a Quantl value of 1, the largest marsh units will have a Quantl value of 5.

Create attribute "AssetScore" to estimate the protection a marsh unit provides to an asset (building). The Asset Score is calculated by dividing the maximum Coastal Change Likelihood (USGS_CCL_MaximumCCL_2022.tif) score within 100 m of an asset by the distance in meters (binned) from the asset to the marsh unit. The Asset Score ranges from 0 (minimal protection provided by marsh unit) to 10 (maximal protection).
1)PROJECT source shapefiles from WGS 1984 Web Mercator coordinate system to NAD 83 (2011) UTM 18N and output as feature classes within a geodatabase to ensure distance calculations are accurate. Source files: marsh units: [FIIS_SDM_Metrics.shp]; buildings (use only NPS buildings): [FIIS_Building_Polygon]; output: [FIIS_BuildingFeatures_UTM18].
2)Calculate the maximum CCL value within 100 m of each of the assets (buildings) within FIIS boundary. BUFFER [FIIS_BuildingFeatures_UTM18] by 100 m, output= [FIIS_BID100mBuff]. ZONAL STATISTICS AS TABLE (Input: [FIIS_BID100mBuff]; zone field=BID; Input Value Raster: [USGS_CCL_2022.tif]; Output table: [FIIS_BuildingMaxCCL_100m]; Statistics Type=Maximum).
3)Calculate the distance in meters from the buildings [FIIS_BuildingFeatures_UTM18] to the closest point along the boundary of all marsh units [FIIS_SDM_Metrics.shp] that are within 1 km of each feature in [FIIS_BuildingFeatures_UTM18]. GENERATE NEAR TABLE (Output table: [FIIS_BuildingsNearMU_1km]). Only need to retain the fields "IN_FID", "NEAR_FID", and "NEAR_DIST" from the output table.
4)Join (JOIN FIELD) the MAX CCL value from table [FIIS_BuildingMaxCCL_100m] (join field=BID) to the output table [FIIS_BuildingsNearMU_1km] (join field=IN_FID; Transfer Fields=MAX).
5)ADD FIELDS (multiple) (Input Table: [FIIS_SDM_Metrics.shp]; Field Names: "Dist" (Short) and "AssetScore" (Double)).
6)ADD JOIN (Join one to many) (Input Table: [FIIS_SDM_Metrics.shp]; input field=OBJECTID; Join Table: [FIIS_BuildingsNearMU_1km]; Join Field: NEAR_FID; transfer all fields). EXPORT joined feature class to [FIIS_SDM_Metrics_AS].
7) Calculate the "AssetScore" field in 2 steps. In [FIIS_SDM_Metrics_AS], first CALCULATE FIELD "Dist" by rounding up the "NEAR_DIST" value (Data type=double from step 3 and 6) in meters to the nearest 100, then dividing the rounded number by 100. For example, a "NEAR_DIST" value of 23.55 m rounds to 100, then divided by 100 gives a “Dist” value of 1; a "NEAR_DIST" of 176.16 m gives "Dist" value of 2. Second, CALCULATE FIELD "AssetScore" by dividing "MAX" (max CCL) by "DIST."
8)Run PAIRWISE DISSOLVE (input file: [FIIS_SDM_Metrics_AS]; Dissolve field: FID_CMU; Statistics field: AssetScore; Statistics Type: Maximum; Output: [FIIS_SDM_Metrics_AS_Dissolve]) to dissolve duplicate "FID CMU" records from the one-to-many join in step 6. This final step retains the maximum "AssetScore" for any one-to-many relationships between each marsh unit and building pair(s). The output dissolved feature class does not retain all the fields from the source [FIIS_SDM_Metrics_AS] and only retains "FID_CMU" and "MAX_AssetScore."
9)JOIN FIELD "MAX_AssetScore" from [FIIS_SDM_Metrics_AS] back into original source [FIIS_SDM_Metrics.shp] using the "FID_CMU" field.

Create attribute “VegMU_MgC” to summarize the amount of biomass carbon in the vegetated part of the marsh unit.
Extract the vegetated portion of the marsh unit polygons. SELECT BY ATTRIBUTES from [CMU_FIIS.shp] within and adjacent to the park boundary [NPS_boundary.shp] where "TYP"= 'vegetated'; output: [CMU_FIIS_VEG.shp]. PROJECT [CMU_FIIS_VEG.shp] to Albers_Conical_Equal_Area to match the projection of the biomass carbon file.
Run ZONAL STATISTICS AS TABLE (feature zone data: [CMU_FIIS_VEG.shp], zone field: FID_CMU, value raster: [BiomassC_CONUSTidalMarshes_gCm2.tif], Statistics type=Mean) to get the average biomass carbon for the vegetated portion of the marsh unit. JOIN the MEAN value to [CMU_FIIS_VEG.shp]. Multiply MEAN by the vegetated area of the marsh unit to get total grams of carbon in the vegetated portion of the marsh unit. Report the value in megagrams of carbon (MgC). Assign a value of -9999 for marsh units that do not have carbon data.

Create new attribute “Pop” to calculate the total population within 50 miles of the marsh units. The population value is the same for all marsh units.
SELECT BY LOCATION (intersect, 50 miles) [Census_Blocks.shp] and [FIIS_SDM_Metrics.shp]. Calculate total population in the selected census blocks.

Create attribute “Edu_Val” that identifies marsh units that are of natural and cultural history educational value to the park. For FIIS, marsh units within 200 m of visitor's centers, the Floyd Estate, the Watch Hill Boardwalk, walking trails, and the Sunken Forest are identified.
SELECT BY LOCATION (intersect, 200m) [Locations_Interest.shp] and [FIIS_SDM_Metrics.shp] to identify marsh units that are within 200 m of the features of interest. If the features are within 200 m of the marsh unit, the marsh unit is assigned a value of 1.

Create attribute “Rec_Val” that identifies marsh units that are of recreational value to the park. For FIIS, marsh units within 100 m of walking trails, the Watch Hill boardwalk, roads (4WD and regular), campsites, boat access points, the wilderness area, Sunken Forest and the Floyd Estate are identified.
SELECT BY LOCATION (intersect, 100m) [Locations_Interest.shp], [Campsites.shp], [Roads.shp], [Ferry_Terminals.shp], [Wilderness.shp] and [FIIS_SDM_Metrics.shp] to identify marsh units that are within 100 m of these features. If the features are within 100 m of the marsh unit, the marsh unit is assigned a value of 1.

Create new attribute “Visit” that is the total number of visitors to the park in 2023. This value is the same for all marsh units.
The number of visitors to FIIS in 2023 was obtained from [Annual_Visitation].

Create attribute "Wild" that identifies marsh units that are within the Wilderness Area.
SELECT BY LOCATION (intersect) [Wilderness.shp] and [FIIS_SDM_Metrics.shp] to identify marsh units that intersect the Wilderness area of FIIS. If they intersect, the marsh unit is assigned a value of 1.

Create 3 attributes “NHS,” “CL,” and “NHS_CL” to identify marshes that are close to cultural and historical resources. "NHS" identifies marsh units that are within 1 km of a historic site (National Historic Site (NHS), National Register of Historic Places (NRHP)), "CL" identifies marsh units that are within 1 km of a Cultural Landscape (CL). The attribute "NHS_CL" indicates marsh unit that are within 1 km of either an NHS or CL site or both (value of 1 or 2, respectively).
Dennis Skidds (NPS) aggregated the park-restricted data to determine whether a marsh unit is within 1 km of the cultural and historical resources.

Create an attribute "Arch" to denote whether a marsh unit is within 100 m of an area of archeological concern.
SELECT BY LOCATION (intersect) [FIIS_Arch_Concern.shp] and [FIIS_SDM_Metrics.shp] to identify marsh units that are within 100 m of an area of archeological concern. If the features are within 100 m of the marsh unit, the marsh unit is assigned a value of 1.

Create an attribute "InOutPark" to denote whether a marsh unit is inside or outside of the park boundary. SELECT BY LOCATION (intersect) [NPS_boundary.shp] and [FIIS_SDM_Metrics.shp] to identify whether the marsh unit is inside or outside of the park boundary.

PROJECT (Output coordinate system=WGS 1984 Web Mercator Auxiliary Sphere) [FIIS_SDM_Metrics.shp] to Web Mercator.