Sources for the Combine Bathymetry and Topography of the Puget Lowlands, Washington (January 2005) digital elevation model

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How should this data set be cited?

   Finlayson, David, 20040131, Sources for the Combine Bathymetry and Topography of the Puget Lowlands, Washington (January 2005) digital elevation model.

   Online Links:

   • <http://www.ocean.washington.edu/data/pugetsound/>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -124.030870

   East_Bounding_Coordinate: -121.966781

   North_Bounding_Coordinate: 48.537448

   South_Bounding_Coordinate: 46.963212

3. What does it look like?

   

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 31-Jan-2005

   Currentness_Reference: publication date

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: raster digital data

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions 18692 x 16406 x 1, type Grid Cell

   2. What coordinate system is used to represent geographic features?

      The map projection used is Lambert Conformal Conic.

      Projection parameters:

      Standard_Parallel: 47.500000

      Standard_Parallel: 48.733333

      Longitude_of_Central_Meridian: -120.833333

      Latitude_of_Projection_Origin: 47.000000

      False_Easting: 1640416.666667

      False_Northing: 0.000000

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 30.000000
      Ordinates (y-coordinates) are specified to the nearest 30.000000
      Planar coordinates are specified in survey feet

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.
      

7. How does the data set describe geographic features?

   psdem2005_src (the value of the raster)

   This is an integer which is keyed to a table of data sources

   ObjectID

   Internal feature number. (Source: ESRI)

   Value	Definition
   1	No source for this elevation value. The value was interpolated during the construction of the DEM
   2	Terrapoint, Inc. (2000-2004) LIDAR topography of the Puget Lowlands. Under contract with the Puget Sound Lidar Consortium (LIDAR)
   3	Troost, Kathy (unpublished) Digital contours of Lake Washington. The Pacific Northwest Center for Geologic Mapping. Unviersity of Washington, Seattle, WA (Digitized Contours?)
   4	Haugerud, Ralph (2003) Composite grids of SHOALS bathymetric LIDAR data. US Geological Survey (LIDAR Bathymetry)
   5	Greenberg, Harvey (2001) 10-meter DEM composite of the USGS 10-meter DEM series for Washington State. Earth and Space Sciences, University of Washington, Seattle WA (Digitized Contours?)
   6	Gregg, Mike (2002) R/V Thompson Cruise TN146 and TN147. Applied Physics Laboratory, University of Washington, Seattle WA (Swath Bathymetry)
   7	Gardner, J. (2001) Multibeam mapping the major deltas of southern Puget Sound, WA from Field Activity: R-1-01-WA. US Geological Survey, Coast and Marine Geology (CMG) (Swatch Bathymetry)
   8	David Evans and Associates, Inc. (2004) Lower Duwamish waterway bathymetric survey (swath bathymetry). under contract to the US Environmental Protection Agency and WA ST. Dept. of Ecology. (Swath Bathymetry)
   10	Tenix LADS Corp. Near-shore bathymetry for the Puget Sound Lidar Consortium. Under contract to the Puget Sound Lidar Consortium. (LIDAR bathymetry)
   11	Gelfenbaum, Guy (2001) Nearshore LIDAR bathymetry of Camano Island, Puget Sound, WA. US Geological Survey (LIDAR bathymetry)
   12	Office of the Coast Survey (1931-2000) National Ocean Service Office of the Coast Survey Hydrographic Survey Data. NOAA National Ocean Service (digitized soundings)

   Value

   Count

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • David Finlayson

2. Who also contributed to the data set?

   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.

3. To whom should users address questions about the data?
   David Finlayson
   School of Oceanography, University of Washington
   Ph.D. Candidate
   Geology & Geophysics
   Seattle, WA 98195-7940
   USA
   

   (206) 616-9407 (voice)
   dfinlays@u.washington.edu
   

Why was the data set created?

The purpose of this raster is two fold: (1) to identify the source of each elevation value in the PSDEM, (2) to make it easy to update the DEM for future maintainers.

How was the data set created?

1. From what previous works were the data drawn?

   PSDEM 2005 (source 1 of 1)

   David Finlayson, School of Oceanography, University of , 20050127, Combined bathymetry and topography of the Puget Lowlands (January 2005).

   Online Links:

   • <http://www.ocean.washington.edu/data/pugetsound/>

   Type_of_Source_Media: online

   Source_Contribution:

   This raster documents the elevation sources in the Puget Sound DEM (January 2005).

2. How were the data generated, processed, and modified?

   Date: 31-Jan-2005 (process 1 of 1)

   After the addition of each new dataset into the PSDEM 2005. A difference with the previous grid was calculated and the resulting new cells were flagged in this Source raster.

3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?

   The reported source ID was assigned by differencing the PSDEM after each processing step. This should result in perfect correlation between the source raster and the original DEM. This has not been checked.

2. How accurate are the geographic locations?

   The horizontal accuracy of this DEM has not been tested.

   The horizontal accuracy is a function of the accuracy of the various underlying data sets plus the errors introduced during the production of this DEM (including reprojecting, resampling and adjusting the horizontal datum). With the exception of the NOS conventional soundings, all data sources had a higher horizontal resolution than the 30-foot resolution for this DEM. A best-guess would be that cell values are accurate to within 1-cell spacing (30-feet)

3. How accurate are the heights or depths?

4. Where are the gaps in the data? What is missing?

   There are no intentional data gaps in this converage. Every cell in the PSDEM 2005 should have a source value in this map.

5. How consistent are the relationships among the observations, including topology?

   Because this raster can only hold one data value per cell, it follows that only one data source can be associated with each cell. In many places in the DEM two data sources were blended together to smooth the margins between data, especially if the transition was from a high resolution source to a low resolution source. The policy followed on land (NAVD88 > 0), was to record only the lowest resolution source. The policy on the water (NAVD88 <= 0) was to record the highest resolution source. This later situation is regrettable, but irreversible without rebuilding the DEM. To make matters somewhat better, the overlap between the NOS bathymetry and the swath bathymetry was always 300 feet from the edge. This region should be flagged as having a hybrid source.

   For all data sources except the NOS bathymetry, the source data was of equal or higher spatial resolution than the DEM (30-foot). So, for these datasets I assigned every cell within the data hull to the source. The NOAA bathymetry however was of much lower resolution. In the deeper parts of the Sound the spacing between soundings can be on the order of 2000 ft or more. I chose to identify only those cells within a 200 foot range of a sounding as belonging to NOAA, the remaining values were assigned to my interpolation class.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:

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.

Use_Constraints: None

1. Who distributes the data set? (Distributor 1 of 1)
   David Finlayson
   School of Oceanography, University of Washington
   

   (206) 616-9407 (voice)
   dfinlays@u.washington.edu
   

2. What's the catalog number I need to order this data set?

   Downloadable Data

3. What legal disclaimers am I supposed to read?

   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.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	Size: 10.109

   • Cost to order the data: This is a fee dataset

   • Special instructions:

     These data are available for download at <http://www.ocean.washington.edu/data/pugetsound/>

5. Is there some other way to get the data?

   None

6. What hardware or software do I need in order to use the data set?

   None

Who wrote the metadata?

Dates:

Last modified: 31-Jan-2005

Metadata author:

School of Oceanography, University of Washington
c/o David Finlayson
Ph.D. Candidate
Marine Geology & Geophysics
Seattle, WA 98195-7940
USA

(206) 616-9407 (voice)
dfinlays@u.washington.edu

Metadata standard:

FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Metadata extensions used:

• <http://www.esri.com/metadata/esriprof80.html>