David Finlayson, School of Oceanography, University of Washington 20050124 1.0 (January 2005) raster digital data http://www.ocean.washington.edu/data/pugetsound/ This dataset represents a composite of the best-available bathymetry and topography for Puget Sound, Hood Canal, Lake Washington and the surrounding lowlands as of January 2005. This is a general purpose digital elevation model (DEM). It should prove to be particularly useful for researchers and managers who are concerned with the interface between terrestrial and marine topography. The bathymetry and topography are properly represented and seamless. Although a large percentage of the data is derived from state-of-the-art mapping systems collected as recently as 2004 (including laser altimetry and swath bathymetry) it was sometimes necessary to rely on very old datasets such as lead-line from the 1930's to complete the model. Care was taken to ensure that each dataset was properly projected, resampled and adjusted into a common vertical and horizontal datum (NAVD88 and NAD83 respectively). Obvious artifacts in the data were removed where this was easily done, and an effort was made to smooth the transition between datasets to minimize the number of spurious artifacts along data set margins. 1931 unknown 2004 unknown ground condition Complete As needed -123.037074 -122.465531 48.021275 47.476767 None Elevation Topography Bathymetry DEM None Puget Lowlands Puget Sound Hood Canal Admiralty Inlet Saratoga Passage Port Susan Skagit Snohomish King Pierce Thurston Jefferson Mason Kitsap Island Washington This work is licensed under the Creative Commons Attribution License. To view a copy of this license, visit http://creativecommons.org/licenses/by/2.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. NOT TO BE USED FOR NAVIGATION David Finlayson School of Oceanography, University of Washington Ph.D. Candidate mailing address

Marine Geology & Geophysics

School of Oceanography

Box 357940

University of Washington

Seattle WA 98195-7940 USA (206) 616-9407 dfinlays@u.washington.edu david.p.finlayson@gmail.com g1230480.jpg JPEG Funding for this project was provided by Washington SeaGrant and the U.S. Army Corps of Engineers. A Special thank you to Ralph Haugerud, Harvey Greenberg and Elizabeth Cassel without whose assistance this DEM could not have been completed. Most importantly, this project relies on Public Domain elevation data provided by the Puget Sound Lidar Consortium (PSLC), the U.S. Geological Survey (USGS), the National Ocean Service (NOS), the University of Washington (UW), and the Lower Duwamish Working Group (LDWG). Please support public access to publicly funded data so that projects like this can be made possible. Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.0.0.535 See Vertical Accuracy Report No logical consistency tests have been performed on this dataset. This DEM has been visually inspected for completeness. Voids in the data are found in the Strait of Juan de Fuca at approximately the northern extent of U.S. territorial waters. Additional voids may result due to the orientation of the bounding box of the data relative to the Washington State Plane North (WA SPN) projection grid. No other voids are intentional. The horizontal accuracy of this DEM has not been tested. The horizontal accuracy is a function of the accuracy of the underlying data plus the errors introduced during the production of this DEM (including reprojecting, resampling and adjusting the horizontal datum). 30 feet This is the cell resolution and represents an educated guess. The vertical accuracy of this DEM has not been tested. The vertical accuracy is a function of the accuracy of the underlying data (see data sources section) plus the errors introduced during the production of this DEM. Production of the DEM included reprojecting the data to Washington State Plane North; converting units from meters to feet; adjusting the vertical datum to NAVD88 using CORPSCON 5.11.08 (for terrestrial data); VDatum 1.06 (marine data south of 48 10'); or by adding a value from a NAVD88 correction surface developed from NOS tidal benchmarks for soundings north of 48 10' (see processing steps section for details), and finally resampling the data to a 30-foot raster resolution. In addition to the transformation errors described above, bathymetry-bathymetry and terrestrial-terrestrial overlapping data sets were merged together by using the ArcGIS 9.0 "Mosaic to New Raster" command with the "Blend" option. This proprietary algorithm feathers overlapping datasets into one another to minimize edge artifacts. It will also lower the fidelity of accurate datasets when they are "blended" with lower fidelity data. unknown The vertical error is dependent on the data source and post processing. Lidar (both bathymetric and terrestrial) error is <2 feet for the original 6-foot pixels, Swath bathymetry and NOS sounding error are depth dependent but should be <5 feet at 300 foot depth, USGS 10-m DEM error can exceed 50 feet. Terrapoint, The woodlands, TX 20040427 raster digital data Available from the Puget Sound Lidar Consortium, Seattle, WA http://rocky2.ess.washington.edu/data/raster/lidar/index.htm 12000 online 2000 2004 ground condition Terrapoint Lidar Lowland topography down to Mean High Water (see source graphic) Ralph Haugerud, US Geological Survey Joint Airborne Laser Bathymetry Technical Center of Expertise (JALBTCX) 20040610 raster digital data These data were originally collected by the Puget Sound Lidar Consortium. Ralph Haugerud adjusted the data to NAVD88 and interpolated the grids into composites. These composite grids were used here. 24000 DVD-ROM 200309 200310 ground condition SHOALS LIDAR Beach and marine data for portions of the Skagit Delta, Lowfal, Seattle, and WIRA9 Tenix LADS Corp. 200104 raster digital data Under contract with the Puget Sound Lidar Consortium 24000 DVD-ROM 200104 ground condition Tenix LADS Beach and marine waters of Southeast Whidbey Island from Randall Point to Possession Point and south of Mukilteo Guy Gelfenbaum, U.S. Geological Survey 20030325 tabular digital data 24000 CD-ROM 20021002 ground condition SHOALS LIDAR (Camano Island) Beach and Marine shallows of western Camano Island James V. Gardner, United States Geological Survey, Coast and Marine Geology (CMG) 20010319 raster digital data Openfile report 01-266 http://geopubs.wr.usgs.gov/open-file/of01-266/ 24000 online 20010319 20010330 ground condition USGS Swath Bathymetry Swath Bathymetry for the Duwamish, Puyallup and Nissqually River Deltas. David Evans and Associates, Inc., 2100 SW River Parkway, Portland, OR. 97201 20040206 Prepaired for Windward Environmental LLC, 200 West Mercer Street, Suite 401, Seattle, WA. For submittal to: The US Environmental Protection Agency, Region 10, Seattle, WA The Washington State Department of Ecology, Northwest Regional Office, Bellevue, WA http://www.ldwg.org/rifs_doc.htm 12000 online 20030825 20030829 ground condition LDWG Swath Bathymetry Swath bathymetry for the Lower Duwamish River Channel Mike Gregg, Applied Physics Laboratory, University of Washington, Seattle, WA Unpublished Material Post Processing by David Finlayson 24000 CD-ROM 20020519 20020523 ground condition UW Swath Bathymetry Portions of Admiralty Inlet and Possession Sound Office of Coast Survey, NOAA National Ocean Service 20050101 tabular digital data Downloaded from the web interface to GEODAS. http://www.ngdc.noaa.gov/mgg/bathymetry/hydro.html 40000 online 1931 2000 ground condition NOS Soundings Major source of bathymetry (all bathymetry not collected by multibeam). Harvey Greenberg 20011204 This 30-foot grid was delivered to me by Harvey Greenberg in Washington State Plane North (feet) at 30-foot resolution, NAD83, NAVD88. The data was derived from a composite DEM Harvey built out of USGS 10-meter DEMs in UTM Zone 10 North, NAD27, NGVD29 http://rocky.ess.washington.edu/data/raster/tenmeter/index.html 24000 online unknown ground condition UW 10-m DEM All terestrial elevations not included in the LIDAR datasets Kathy Troost, The Pacific Northwest Center for Geological Mapping Studies, University of Washington Unpublished Material This dataset has an unknown lineage. It appears to be derived from NOS Nautical Chart 18447, however, the name of the original person who digitized the data has been lost. electronic mail system unknown ground condition GeoMap Lake Washington Contour elevation data for Lake Washington Terrapoint LIDAR was delivered gridded at 6-foot resolution, Washington State Plane North. However, it still included water-surface data. We manually traced the marine waterline and extracted the topography. I also filled several thin (1-2 pixel wide) linear artifact gaps in the dataset by using the EUCALLOCATION function to smooth over the gaps. This dataset was then resampled to 30-foot resolution and formed the basis of the "Master DEM". Terrapoint Lidar 2004 David Finlayson The SHOALS Bathymetric LIDAR datasets were delivered in NAD83, NAVD88 by Ralph Haugerud. However, the LADS data off Whidbey and the SHOALS data off Camano Island were still in MLLW. I used VDatum to convert the LADS data to NAVD88. However, Camano Island is north of where VDatum works (48 degrees 10 minutes). I resorted to looking up the NAVD88 value of MLLW at Crescent harbor (-73cm) and Glendale on Whidbey Island (-67cm) and split the difference (-70cm) for the Camano Island dataset. I then interpolated the two datasets into a raster in Washington State Plane North feet (NAD83). Finally, I merged all of these datasets into the Master DEM by allowing the bathy LIDAR to fill NODATA gaps in the Master DEM. SHOALS LIDAR Tenix LADS SHOALS LIDAR (Camano Island) 200412 David Finlayson The Lake Washington Bathymetric Contours were compared with NOS Chart 18477. Contour depths were determined to be in the vertical datum "Low Water of the Lake" which is 20 feet above MLLW and 18.75 feet above NAVD88 at the entrance to the Locks). A raster DEM was created in NAVD88 by TINing the contours and then trimming the results to a manually drawn polygon outlining the two lakes and the canal. This dataset was merged into the Master DEM by filling the NODATA areas associated with Lake Washington, Lake Union and the ship canal above the locks. GeoMap Lake Washington 200412 David Finlayson The NOS soundings were downloaded from the internet and projected into Washington State Plane North using CORPSCON 5.11.08. The data was then split into two parts at 48 degrees 10 minutes North. Soundings south of this line were converted from MLLW to NAVD88 using VDatum (48 10 is the northern limit of VDatum). Soundings north of this line were gridded in MLLW and then adjusted to NAVD88 using a correction surface interpolated from NOS tidal benchmarks. This later processing step introduces 0.75 cm error (established by cross-validation of the NAVD88 surface). Otherwise the two point sets were treated the same. First the data was divided into 10 tiles of 0.5 x 0.5 degree extent (this was necessary to save memory while interpolating at 30-foot resolution). All of the points within the tile plus a 1 km overlap were gridded using a TIN interpolator. This TIN included a thin ribbon of points taken from the shoreline of the MASTER DEM to ensure that the TIN merged perfectly at the shoreline. The TIN was converted to a raster and a shaded relief map was produced from the raster. Obvious errors in the data were edited out of the point file. This process was repeated until all obvious errors in the bathymetry were eliminated. NOS Soundings 200412 David Finlayson The USGS Swath Bathymetry, UW Swath Bathymetry and LDWG Swath Bathymetry were treated similarly. Each dataset was downloaded from the internet (except the UW data) as point files. They were projected to Washington State Plane North in CORPSCON 5.11.08 and imported to ArcGIS as points. The points were gridded using a TIN interpolator and converted to a raster. The raster was trimmed using a manually drawn polygon that outlined the data area. Finally, the raster was converted from MLLW to NAVD88 by applying a single correction value determined in VDatum for the centroid of the dataset. The resulting raster was subtracted from the appropriate NOS hydrographic tile(s) and a mean difference was established between the two elevation datasets. The correction was applied to the Swath Bathymetry (since these data were not vertically controlled to survey grade) so that the two datasets approximately matched. The corrections applied were: -4.16 ft (Duwamish Delta), -7.3 ft (Puyallup), -5.14 ft (Nisqually Delta), +6 ft (Possession Sound), +5.6 (Admiralty Inlet). The low-resolution NOS bathymetry was trimmed around the swath bathymetry with a 300 ft overlap. Then these datasets were merged together using ArcGIS's "Mosaic to New Raster" with the "Blend" option, which is a proprietary algorithm that feathers the two data sets into one another reducing the margin artifacts. The Admiralty Inlet swath bathymetry from the UW overlapped three tiles. Since the low-resolution NOS bathymetry was mathematically identical in each of the three tiles (where they overlapped) only a single correction was necessary (+5.6 ft). USGS Swath Bathymetry LDWG Swath Bathymetry UW Swath Bathymetry 200412 David Finlayson A manually drawn polygon was used to outline gaps in the Master DEM that were to be filled with the lower quality data from Harvey Greenberg. This prevented the low-quality data from spoiling areas where there was good LIDAR data (but the two datasets did not agree on how it should look) and allowed the low-quality data to fill areas in the Master DEM where there were real gaps in the LIDAR. I used ArcGIS's proprietary "Mosaic to New Raster" with the "Blend" option to smooth the transition between the low-quality elevation data and the high-quality LIDAR-derived data. The overlap between the two datasets was hand-drawn and varied from a few hundred feet in the eastern Puget Lowlands, to many hundreds of feet over the Olympics. UW 10-m DEM David Finlayson For each of the 10 tiles there was a bathymetry raster and a portion of the Master DEM. The two portions were merged using the bathymetry raster to fill NODATA areas in the Master DEM. Next, all 10 tiles were merged together into a single DEM. A few NODATA gaps remained in River Channels. And I set back to NODATA a few small areas that had obvious errors (like the seam between the Lidar Bathymetry and Multibeam bathymetry off Alki Point), a mountain in Elliott Bay that doesn't exist, etc. I then interpolated over the gaps using a TIN made from the pixels surrounding each data gap. This formed the final DEM. 200501 David Finlayson Metadata imported. C:\DOCUME~1\David\LOCALS~1\Temp\xmlC2.tmp Raster Grid Cell 6510 4526 1 Lambert Conformal Conic 47.500000 48.733333 -120.833333 47.000000 1640416.666667 0.000000 row and column 30.000000 30.000000 survey feet North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 North American Vertical Datum of 1988 1 feet Explicit elevation coordinate included with horizontal coordinates North American Vertical Datum of 1988 1 feet Explicit depth coordinate included with horizontal coordinates Elevation none The digital elevation model is composed of an elevation value linked to a grid cell location representing a gridded form of a topographic map hypsogrphy overlay. Each grid cell entity contains a 16-bit integer value between -32,767 and 32,768 Puget Sound Digital Elevation Model (January 2005) Although these data have been processed successfully on a computer system at the University of Washington, no warrenty expressed or implied is made by the University of Washington regarding the utility of the data on any other system, nor shall the act of distribution constitude any such warranty. 114.781 No Fees These data are available for download at http://www.ocean.washington.edu/data/pugetsound/ 20050124 School of Oceanography, University of Washingon, Seattle, WA David Finlayson Ph.D. Candidate mailing address

Marine Geology & Geophysics

School of Oceanography

Box 357940

University of Washington

Seattle WA 98195-7940 USA (206) 706-1196 dfinlays@u.washington.edu david.p.finlayson@gmail.com FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time None None NA http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile