shoreline, inletLines: Shoreline polygons and tidal inlet delineations: Rhode Island National Wildlife Refuge, RI, 2014

Full methods are provided in the associated Methods OFR (Zeigler and others, 2019).
ri14_shoreline.shp:
A polygon outlining the shoreline of the barrier was created for the study area. On the ocean-facing side, this was considered the MHW contour (Weber and others, 2005, Zeigler and others, 2019). To include partially submerged wetland on the estuarine-side, the land-facing shoreline was delineated at mean tidal level (MTL), which was calculated from the local MHW and mean low water (MLW) levels at the given study area.
The local MLW elevation was estimated from NOAA’s VDatum (2014 release) as the average MLW elevation at a sample of nearshore points in the study area. Experimentation conducted as part of this study found that the MTL delineation more consistently identified the boundary between marsh (intertidal vegetation) and submerged areas than either MHW or MLW. For consistency with the MHW offset applied throughout the project, MHW was used as part of the calculation of MTL.
To create this shoreline, we performed the following steps. Most of the steps were performed programmatically using the function functions_warcpy.DEMtoFullShorelinePoly in bi-transect-extractor (Sturdivant, 2019):
1. Convert the shoreline points CSV to a multipoint feature class in reference system NAD_1983_UTM_Zone_19N. This was performed in ArcGIS 10.5 using the tools Make XY Event Layer and Project. The datum transformation used was WGS_1984_(ITRF00)_To_NAD_1983 (WKID: 108190, accuracy: 0.1 m).
2. Manually digitize lines from the DEM that indicate where land meets a tidal inlet, which is considered the division point between the oceanside and the bayside or estuarine side of the barrier. This line was visually approximated.
3. Create a generalized polygon from the DEM in which every cell within the polygon is above MHW (MHW polygon). This was performed programmatically using the function functions_warcpy.RasterToLandPerimeter in bi-transect-extractor v1.0 (Sturdivant, 2019). Although the Rhode Island study area included three MHW elevation values (Weber and others, 2005), the median value (0.29 m) was used as the MWH elevation for the full site when creating the shoreline polygon. This was counteracted in subsequent steps by snapping the polygon to the shoreline points. The process includes generalizing the polygons (Aggregate Polygons tool in the Cartography toolbox) using an aggregation distance of 10 m, a minimum area of 300 m2, and a minimum hole size of 300 m2.
4. Repeat Step 3 for MTL, using an MTL elevation of -0.065 m NAVD88.
5. Merge the polygons so that the MHW contour outlines the barrier on the oceanside and the MTL contour outlines the bayside (if a bayside shoreline exists), divided at the delineated tidal inlets. To do so, create a symmetrical difference polygon between MHW and MTL polygons (SymDiff) and split the resulting polygon at the inlet lines (Feature to Polygon). Create a polygon that outlines only the bayside area that is above MTL and below MHW (MTL-only polygon) by deleting the segments of the symmetrical difference polygon that overlap shoreline points (Spatial Join, Erase). Merge the MTL-only polygon with the MHW polygon (Union, Dissolve). This was performed using the function functions_warcpy.CombineShorelinePolygons in bi-transect-extractor (Sturdivant, 2019).
6. Adjust the vertices of the polygons to precisely match the MHW shoreline positions wherever they are within 25 m of each other (Doran and others, 2017). This was performed using the function functions_warcpy.NewBNDpoly in bi-transect-extractor (Sturdivant, 2019). That snaps the polygon to the shoreline points where it is within 25 m of a point (Snap tool in the Edit toolbox, ArcGIS 10.5).
7. QA/QC the output and manually revise any sections where the point snapping created clearly incorrect artifacts.
The dataset contains 10 polygons.
Some portions of the Rhode Island site are located on the mainland, which prevents the data from representing a back-barrier shoreline. To address this, the so-called back-barrier shoreline was clipped to a straight line roughly parallel and about 250 m from the shore polygons. If an inland waterbody occurred about 250 m from the shore, then the back-barrier shoreline was clipped to run through the waterbody.

Full methods are provided in the associated Methods OFR (Zeigler and others, 2019). The Jupyter notebook used for processing is distributed with the larger work dataset in IPYNB format (extractor_ri14.ipynb).
ri14_inletLines.shp
Display the DEM with a color break at mean high water (MHW) elevation. Manually digitize a straight line that bisects MHW where the seaward shoreline meets a tidal inlet, which is also considered the division point between the ocean-side and bay- or estuarine-side of the barrier. This line was visually approximated. The dataset contains 14 polylines.

Added keywords section with USGS persistent identifier as theme keyword.