Shoreline change rates in salt marsh units in Edwin B. Forsythe National Wildlife Refuge, New Jersey

This process step used ArcMap (ver. 10.3.1) using tools from ArcToolbox. Names of specific tools used are given in CAPITAL letters (any critical parameters used is given in parentheses, separated by a semicolon, immediately after the tool name). 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.
Shoreline change rates for EBFNWR are based on the "Shoreline Change Analysis of Coastal and Estuarine Shorelines in Barnegat and Great Bays, NJ: 1839 to 2012" by Smith and Terrano (2017) version 1.1. Download the shoreline change data, NJ_SLC_transects, for mainland (NJ_SLC_mainland.zip), estuarine barrier (NJ_SLC_backshore.zip), and islands (NJ_SLC_islands_and_tribs.zip) in Barnegat Bay, New Jersey. Use the transect shapefiles in these datasets in the following steps. Because the data are in separate files, they need to be merged and any overlapping parts need to be cleaned in order to have the values from the most relevant dataset. For example, in order to obtain mainland values exclusively from mainland transects, the transects from any other datasets that extend over the mainland are removed).
a) Create a 100 m buffer around [tributaries_transects.shp] with BUFFER(Side type= Full; Method =Geodesic; Dissolve type= All) to obtain [trib_buff.shp].
b) MERGE mainland and backshore transects to obtain [main+back.shp].
c) SELECT LAYER BY LOCATION(Input feature='main+back', Relationship='Intersect', Target features='trib_buff') to select features from [main+back.shp] that intersect with buffered tributaries transects layer.
d) Invert selection and export the dataset as [main+back_gap.shp]
d) MERGE [tributaries_transects.shp] with [main+back_gap.shp] to obtain a data layer that covers mainland, backshore, tributaries and islands without the overlap with the tributaries, [main+back+trib.shp].
e) Follow similar steps to remove the islands transects overlapping with the rest of the datasets. Create a 100 m buffer around [islands_transects.shp] with BUFFER(Side type= Full; Method =Geodesic; Dissolve type= All) to obtain [island_buff.shp].
f) SELECT LAYER BY LOCATION(Input feature='main+back+trib', Relationship='Intersect', Target features='island_buff') to select features from [main+back+trib.shp] that intersect with buffered islands transects layer. g) Invert selection and export the dataset as [main+back+island_gap.shp].
h) MERGE [islands_transects.shp] with [main+back+trib_gap.shp] to obtain [all_transects_merge.shp], which has the transects from all datasets without any overlaps.
i) PROJECT(Geographic Transformation='WGS_1984_(ITRF00)_To_NAD_1983') the data to Web Mercator coordinate system, which is also the projection for the conceptual salt marsh units [marshUnitsEBFp.shp].
j) ERASE the marsh polygons [marshUnitsEBFp.shp] from the transects [all_transects_merge.shp], and manually remove the transect parts that cross beyond the coastline and through multiple marsh units to obtain the final transects [all_transects.shp].

Calculate shoreline length for each marsh unit.
a) Prepare the shorelines to be selected by POLYGON TO POLYLINE(Input features='marshUnitsEBFp.shp'; Output feature class='mu_clean_line.shp'). Convert MULTIPART TO SINGLEPART(Input features='mu_clean_line.shp'; Output feature class='mu_clean_line_single.shp').
b) Prepare the polyline to be used for selecting. First create the outline by DISSOLVE(Input features='marshUnitsEBFp.shp'; Output feature class='mu_clean_diss.shp') and POLYGON TO POLYLINE(Input features='mu_clean_diss.shp'; Output feature class='mu_clean_diss_line.shp')
c) Use select by location menu to select from [mu_clean_line_single.shp] that intersect with [mu_clean_diss_line.shp] and export it to [mu_shoreline.shp]. Manually edit the layer to remove the outlines that are not shorelines.
d) ADD GEOMETRY ATTRIBUTES(Geometry properties='length_geodesic'; Length unit='meters') to [mu_shoreline.shp]. Calculate the shoreline length per marsh unit by DISSOLVE(Dissolve field='FID_CMU'; STATISTICS='SUM') to get [mu_shoreline_length.shp].
e) JOIN FIELD(Input table='marshUnitsEBFp.shp'; Input join field='FID_CMU'; Join table='mu_shoreline_length.shp'; Output join field='FID_CMU'), Join fields='SUM_LENGTH')
f) EXPORT joined marshUnitsEBFp.shp with shoreline length data to [mu_clean_with_shorelength]

Calculate the transect coverage and mean LRR shoreline change in each marsh unit. Transect coverage is the average shoreline length represented by the transects in a marsh unit.
a) SPATIAL JOIN(Target features='mu_clean_with_shorelength.shp'; Join features='all_transects.shp'; Output features='mu_trans_join.shp';Join_one_to_many; Match option='INTERSECT') to assign LRR values to the intersecting marsh units.
b) Calculate the mean LRR for each marsh unit with SUMMARY STATISTICS(Input table='mu_trans_Join.shp'; Output_table='s'; Statistics Fields=LRR; Statistics type='MEAN'; Case field='TARGET_FID').
c) Calculate total number of transects intersecting the shoreline with SUMMARY STATISTICS. ADD the TRANS_PER field and calculate it as the total shoreline length divided by the number of transects. Assign a value of -1 if the number of transects is equal to zero.
d) Assign the calculated mean LRR to each marsh unit with ADD JOIN(Layer name='marshUnitsEBFp'; Input join field='FID_CMU'; Join table='s'; Output join field='TARGET_FID', Keep_all_target_features). Assign the shoreline length and transect coverage fields similarly.
e) Edit the attribute table to choose fields to keep and to format the field names. Export the dataset as final output [mu_LRR_EBFNWRp.shp]

Added keywords section with USGS persistent identifier as theme keyword.