Haeussler, Peter J. (ORCID: 0000-0002-1503-6247) Labay, Keith A. (ORCID: 0000-0002-6763-3190) 20220121 raster and vector digital data Anchorage, Alaska U.S. Geological Survey, Alaska Science Center Suggested Citation: Haeussler, P.J., Labay, K.A., 2022, Combined high-resolution topography and bathymetry for western Passage Canal, near Whittier, Alaska: U.S. Geological Survey Data Release, https://doi.org/10.5066/P9L0Q0AK https://doi.org/10.5066/P9L0Q0AK This dataset is a new Digital Elevation Model (DEM) using the best available high-resolution topography and bathymetry surrounding the area of Whittier, Alaska. We utilized three datasets (1) LiDAR topography collected by the Alaska Division of Geological and Geophysical Surveys (DGGS) in 2012, (2) multibeam echosounder system (MBES) survey of western Passage Canal collected by the USGS in the summer of 2011 (3) and NOAA single-beam soundings collected from September 26-October 18, 1995. This data was produced to aid in tsunami modeling of the region and to aid in understanding landscape change, above and below sea level. These datasets were placed into a common coordinate system, horizontal datum, and vertical datum prior to being merged. The projected coordinate system of Universal Transverse Mercator zone 6 World Geodetic System of 1984 (WGS84) was used for the horizontal coordinates. Z-values in meters were referenced to the tidal datum of Mean Higher High Water. Gaps between the datasets were interpolated to create the final seamless five-meter grid covering the area of interest around Whittier, Alaska. 1995 2012 ground condition Complete None planned -145.9 -148.4 60.9 60.8 USGS Metadata Identifier USGS:ASC430 ISO 19115 Topic Category Oceans Elevation NASA GCMD Earth Science Keyword Thesaurus Earth science USGS Thesaurus Bathymetry Topography LiDAR Multibeam sonar Single-beam echo sounder Land surface characteristics Data Categories for Marine Planning Bathymetry and elevation Marine Realms Information Bank (MRIB) keywords Multibeam echo sounder USGS Geographic Names Information System (GNIS) Alaska Passage Canal Prince William Sound Whittier No access constraints. No use constraints. These data are marked with a Creative Common CC0 1.0 Universal License and are in the public domain. It is requested that this USGS data release be cited for any subsequent publications that reference or utilize these data. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. U.S. Geological Survey, Alaska Science Center Mailing and Physical

4210 University Drive

Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov Haeussler, P.J. Parsons, T. Finlayson, D.P. Hart, P. Chaytor, J.D. Ryan, H. Lee, H. Labay, K. Peterson, A. Liberty, L. 2014 book chapter Submarine Mass Movements and Their Consequences. Advances in Natural and Technological Hazards Research 37:361-370 online Springer Nature Haeussler, P.J., Parsons, T., Finlayson, D.P., Hart, P., Chaytor, J.D., Ryan, H., Lee, H., Labay, K., Peterson, A., Liberty, L., 2014. New imaging of submarine landslides from the 1964 earthquake near Whittier, Alaska, and a comparison to failures in other Alaskan fjords. In: Krastel S. et al. (eds) Submarine mass movements and their consequences: advances in natural and technological hazards research 37:361-370. https://doi.org/10.1007/978-3-319-00972-8_32 https://doi.org/10.1007/978-3-319-00972-8_32 We compared the multibeam data to 1995 NOAA hydrographic surveys H10655 and H10653, which were conventional single-beam surveys with a vertical datum of MLLW. Based on the original filename of the multibeam survey we inferred the vertical datum was NAVD88. However, we found the multibeam data was deeper than the 1995 surveys by a median value of 5.2 m, or 3 to 4 m in relatively flat areas of the surveys. Areas where the multibeam data was shallower could be found in places of expected change such as off river or stream mouths. A check of the original Caris project files used to generate the multibeam survey provided evidence that the vertical datum was likely MLLW rather than NAVD88. In this report, we assume the datum was MLLW. For other surveys see their respective metadata. The data were examined for outliers and none were found. No formal logical accuracy tests were conducted. Each of the three datasets that were assembled to make this dataset have different levels of completeness. A formal accuracy assessment of the horizontal positional information in the dataset has not been conducted. Accuracy may be lower than source datasets due to the datum transformations and interpolation needed to combine data sources. Hubbard, T.D. Wolken, G.J. Stevens, D.S.P. Combellick, R.A. 2013 raster digital data Raw Data File RDF 2013-3 Fairbanks, AK, USA Alaska Division of Geological and Geophysical Surveys Hubbard, T.D., Wolken, G.J., Stevens, D.S.P., and Combellick, R.A., 2013, High-resolution lidar data for the Whittier area, Passage Canal, and Portage Lake, Alaska: Alaska Division of Geological and Geophysical Surveys Raw Data File 2013-3, 5 p. https://doi.org/10.14509/24976 https://doi.org/10.14509/24976 ESRI Grid 20121021 20121025 ground condition LiDAR Topography surrounding Whittier and Passage Canal Finlayson, D. Unpublished material raster digital data Bathymetric Attributed Grid (BAG) 20110815 20110822 ground condition 5MMB This is the source for swath bathymetry in the dataset, typically below 20 m water depth Hydrographic Surveys Division, Office of Coast Survey, National Ocean Service, NOAA, U.S. Department of Commerce 1995 tabular digital data ASCII XYZ 19950926 19951018 ground condition H10653 Passage Canal bathymetry east of 148 degrees 39 minutes west not covered by 5MMB. Hydrographic Surveys Division, Office of Coast Survey, National Ocean Service, NOAA, U.S. Department of Commerce 1995 tabular digital data ASCII XYZ 19951008 19951018 ground condition H10655 Passage Canal bathymetry west of 148 degrees 39 minutes west not covered by 5MMB. Parsons, T. 2011 document online U.S. Geological Survey, Coastal and Marine Hazards and Resources Program (CMHRP) Pacific Coastal and Marine Science Center https://cmgds.marine.usgs.gov/fan_info.php?fan=A0111GA report 20110815 20110822 observed Parsons 2011 Field Activity Details for field activity A0111GA In 2011 the USGS research vessel Alaskan Gyre mapped in Passage Canal, Alaska, using a Reson 7111 multibeam echosounder. USGS processed the bathymetry data post-cruise. The survey line files were imported into Caris HIPS and SIPS software for processing. Water column sound velocity data that was collected throughout the survey was applied to the bathymetry data. The data were cleaned of spurious soundings and the soundings were gridded into 5-m CUBE surface in Caris 7.1.1 and exported the data as a BAG surface. The dataset was converted from BAG format into GeoTIFF format using ArcGIS 10.0.2. 5MMB Unknown Datum was then transformed from WGS84 into NAD83 using ArcGIS 10.0.2 for use with other local datasets in NAD83. Original projection of UTM 6 remained unchanged. 5MMB Unknown Used bicubic interpolation to fill some small gaps within the dataset. The largest area filled was less than 4000 meters squared. Larger gaps still remain within the data. Processing was done using Global Mapper 20.1. 5MMB Unknown Using Global Mapper 20.1 the horizontal datum was transformed to WGS84 and the vertical datum was adjusted to MHHW by making the depth values 3.715 m deeper as determined by the Whittier tide gauge station 9454949. The modified source data was exported to a temporary XYZ file. 5MMB Unknown NOAA single-beam source datasets provided as two XYZ files in geographic coordinates with a horizontal datum of WGS84 and a vertical datum of MLLW. Using Global Mapper 20.1 the points were reprojected to UTM6 and the horizontal datum was transformed to WGS84. The modified source data was exported to a temporary shapefile. H10653 & H10655 Unknown Using ArcGIS 10.8.1 points that overlapped with the LiDAR or multibeam datasets were deleted. The vertical datum was adjusted to MHHW by making the depth values 3.715 m deeper as determined by the Whittier tide gauge station 9454949. H10653 & H10655 Unknown LiDAR source datasets provided as three ESRI grids with a projection of UTM6 NAD83 and a vertical datum of NAVD88. Using Global Mapper 20.1 the horizontal datum was transformed to WGS84 and the vertical datum was adjusted to MHHW by lowering the elevation values 3.395 m as determined by the Whittier tide gauge station 9454949. Returns from the ocean's surface near the coastline were masked using an extent polygon with a coastline digitized from the LiDAR. The modified source data was exported to a temporary XYZ file. LiDAR Unknown The three temporary files were added to Global Mapper 20.1 and used to generate a temporary TIN. This TIN was used to create the final accompanying zipped GeoTIFF. Bathymetric values east of the multibeam extent were masked from the final GeoTIFF. This GeoTIFF was also reprojected to geographic coordinates in WGS84 using the Project Raster tool in ArcGIS 10.8.1. and exported as an ASCII grid file using the Raster to ASCII tool in ArcGIS 10.8.1. The no data value in the ASCII grid is the default -9999. Unknown The coastline for Passage Canal was digitized from the LiDAR dataset using ArcGIS 10.8.1. LIDAR Unknown Extent polygons for the three raster data sources were created in Global Mapper 20.1. Unknown Using ArcGIS 10.8.1 the digitized coastline was used to define the boundary between the LiDAR and 1995 bathymetry polygons. The polygons were then combined using the Union tool to create the final dataset. Unknown Raster Grid Cell 2573 5118 Universal Transverse Mercator 6 0.9996 -147.0 0.0 500000 0.0 coordinate pair 5 5 meters World Geodetic System of 1984 (WGS84) Geodetic Reference System of 1980 (GRS80) 6378137 298.2572 Mean Higher High Water 5 meters Explicit elevation coordinate included with horizontal coordinates Mean higher high water 5 meters Explicit depth coordinate included with horizontal coordinates PassageCanal_topobathy_UTM6_WGS84_GeoTIFF.zip Digital Elevation Model (DEM) in GeoTIFF raster format. Author defined Value Depth in meters to the seabed this dataset -361.6 1377.5 meters Value No data value this dataset -32767 No data Author defined PassageCanal_topobathy_UTM6_WGS84_ASCIIgrid.zip Digital Elevation Model (DEM) in ASCII grid raster format. Author defined Value Depth in meters to the seabed this dataset -359.7 1376.1 meters Value No data value this dataset -9999 No data Author defined PassageCanal_dataextents_browse.zip Vector polygons depicting the extents of the raster data sources. Presented in both ESRI shapefile (SHP) and Keyhole Markup Language (KML) formats. For convenience, also presented as a 'browse image' in PDF format. Author defined SOURCE Name of raster data source this dataset BATHYMETRY_1995 Extent of NOAA single-beam bathymetry Author defined LIDAR Extent of LiDAR topography Author defined MULTIBEAM Extent of multibeam bathymetry Author defined This dataset contains topography and bathymetry for the western part of Passage Canal near the city of Whittier, Alaska. Values are in meters and measured relative to Mean Higher High Water. Author defined U.S. Geological Survey USGS ScienceBase Team Mailing and Physical

Denver Federal Center, Building 810, Mail Stop 302

Denver Colorado 80225 USA 1-888-275-8747 sciencebase@usgs.gov The U.S. Geological Survey, Alaska Science Center is the authoritative source of these data, distributed by ScienceBase (a USGS Trusted Digital Repository). Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data for other purposes or on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. GeoTIFF, ASCII, SHP, KML Raster geospatial data in GeoTIFF format with an accompanying TFW world file; raster geospatial data in ASCII grid format with an accompanying PRJ projection file; vector geospatial data in Esri shapefile format; vector geospatial data in Keyhole Markup Language (KML) format; FGDC metadata in XML and HTML formats. https://doi.org/10.5066/P9L0Q0AK None 20250527 U.S. Geological Survey, Alaska Science Center Mailing and Physical

4210 University Drive

Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov FGDC Content Standard for Digital Geospatial Metadata (CSDGM) FGDC-STD-001-1998