Water elevation projections at King County, Washington

Frequently anticipated questions:

• What does this data set describe?
  1. How might 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 might this data set be cited?
   Parker, Kai A., Nederhoff, Kees, Erikson, Li H., Engelstad, Anita C., Hayden, Maya K., Barnard, Patrick L., and Grossman, Eric E., 20251126, Water elevation projections at King County, Washington: data release DOI: 10.5066/P13HYXKY, U.S. Geological Survey, Pacific Coastal and Marine Science Center, CA.

   Online Links:

   • https://doi.org/10.5066/P13HYXKY

   This is part of the following larger work.
   Parker, Kai A., Nederhoff, Kees, Erikson, Li H., Engelstad, Anita C., Hayden, Maya K., Barnard, Patrick L., and Grossman, Eric E., 2025, CoSMoS-Puget Sound Modeled Flood Hazards at King County - Washington: data release DOI: 10.5066/P13HYXKY, U.S. Geological Survey, Pacific Coastal and Marine Science Center, CA.

   Online Links:

   • https://doi.org/10.5066/P13HYXKY

   Other_Citation_Details:

   Suggested Citation: Parker, K., Nederhoff, K., Erikson L.H., Engelstad, A.C., Hayden, M.K., Barnard, P.L., and Grossman, E.E., 2025, CoSMoS-Puget Sound Modeled Flood Hazards at King County - Washington: U.S. Geological Survey data release, https://doi.org/10.5066/P13HYXKY.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -122.583957
   East_Bounding_Coordinate: -122.024762
   North_Bounding_Coordinate: 47.819631
   South_Bounding_Coordinate: 47.206286
   

3. What does it look like?
4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 2025

   Currentness_Reference:

   publication year

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

   Geospatial_Data_Presentation_Form: GeoTIFF
   

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:

      UTM_Zone_Number: 10
      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.0
      Latitude_of_Projection_Origin: 0.00000
      False_Easting: 500000.0
      False_Northing: 0.00
      

      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 2
      Ordinates (y-coordinates) are specified to the nearest 2
      Planar coordinates are specified in Meters
      The horizontal datum used is NAD83.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.00.
      The flattening of the ellipsoid used is 1/298.257222101.
      

      Vertical_Coordinate_System_Definition:

      Depth_System_Definition:

      Depth_Datum_Name: North American Vertical Datum of 1988
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Implicit coordinate
      

7. How does the data set describe geographic features?

   flood depth projections (Water_elevation_projections-King.zip)

   GeoTIFF files contain projections of water elevations. (Source: Producer defined)

   water elevation

   maximum water surface elevation associated with corresponding flood extent of indicated sea-level rise (SLR) and return period (RP) (Source: model-derived)

   Range of values
   Minimum:	0.06
   Maximum:	21.76
   Units:	meters
   Resolution:	0.01

   Entity_and_Attribute_Overview:

   The data contain water elevations (water surface elevation associated with coincident flood hazards, meters in NAVD88) and are organized by return periods. Return periods include the no storm ‘average’ condition (rp000), and statistical once-a-year storms (rp001), every 10 (rp10), every 20 (rp20) and every 100 years (rp100) storms. File names reflect the geographic area of the projection (County, here King County), the attribute, here water surface elevation (wsel), the sea-level rise (slr) scenario, and the return period (rp) of storm conditions. SLR scenarios are listed in centimeters (cm) and range from no SLR (slr000) to a SLR of 300 cm (slr300). For example, King_wsel_slr200_rp100 contains water elevations for a sea level rise of 200 cm (2 m) during a projected hundred-year storm in King County, Washington. While the data were written out in float32, the valid resolution is 0.01.

   Entity_and_Attribute_Detail_Citation: U.S. Geological Survey
   

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Kai A. Parker
   • Kees Nederhoff
   • Li H. Erikson
   • Anita C. Engelstad
   • Maya K. Hayden
   • Patrick L. Barnard
   • Eric E. Grossman
2. Who also contributed to the data set?
   This work was funded by the United States Geological Survey (USGS) Coastal and Marine Hazards and Resources Program, King County Department of Natural Resources under Statement of Work 21ZPCOLL210705, and the United States Environmental Protection Agency (EPA) under Statement of Work DW-014-92578201/ EPA-CF-0000007695 to the USGS. The contents of this document do not necessarily reflect the views and policies of the EPA, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. Computation resources were supported by the USGS Advanced Research Computing (Falgout and others, 2024).
3. To whom should users address questions about the data?
   U.S. Geological Survey, Pacific Coastal and Marine Science Center

   Attn: PCMSC Science Data Coordinator

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov

Why was the data set created?

How was the data set created?

1. From what previous works were the data drawn?

   DEM (source 1 of 4)

   Tyler, D.J., Danielson, Jeff J., Grossman, Eric E., and Hockenberry, R.J., 2020, Topobathymetric Model of Puget Sound, Washington, 1887 to 2017: U.S. Geological Survey, online.

   Online Links:

   • https://doi.org/10.5066/P95N6CIT

   Type_of_Source_Media: online database
   Source_Contribution: DEM
   

   CMIP6 Waves (source 2 of 4)

   Erikson, Li H., Herdman, Liv, Flanary, Chris, Engelstad, Anita C., Pusuluri, Prasad, Barnard, Patrick L., Storlazzi, Curt D., Beck, Michael, Reguero, Borja G., and Parker, Kai A., 2022, Ocean wave time-series data simulated with a global-scale numerical wave model under the influence historical and projected CMIP6 wind and sea ice fields (ver. 2.0, October 2024): U.S. Geological Survey, online.

   Online Links:

   • https://doi.org/10.5066/P9KR0RFM

   Type_of_Source_Media: online database
   Source_Contribution: CMIP6 Waves
   

   Hydrodynamic Model (source 3 of 4)

   Grossman, Eric E., Tehranirad, Babak, Stevens, Andrew W., VanArendonk, Nathan R., Crosby, Sean, and Nederhoff, Kees, 2023, Salish Sea Hydrodynamic Model: U.S. Geological Survey, online.

   Online Links:

   • https://doi.org/10.5066/P946SC3L

   Type_of_Source_Media: online database
   Source_Contribution: Hydrodynamic Model
   

   ERA5 (source 4 of 4)

   Hersbach, Hans, Bell, Bill, Berrisford, Paul, Hirahara, Shoji, Horányi, András, Muñoz-Sabater, Joaquín, Nicolas, Julien, Peubey, Carole, Radu, Raluca, Schepers, Dinand, Simmons, Adrian, Soci, Cornel, Abdalla, Saleh, Abellan, Xavier, Balsamo, Gianpaolo, Bechtold, Peter, Biavati, Gionata, Bidlot, Jean, Bonavita, Massimo, Chiara, Giovanna De, Dahlgren, Per, Dee, Dick, Diamantakis, Michail, Dragani, Rossana, Flemming, Johannes, Forbes, Richard, Fuentes, Manuel, Geer, Alan, Haimberger, Leo, Healy, Sean, Hogan, Robin J., Hólm, Elías, Janisková, Marta, Keeley, Sarah, Laloyaux, Patrick, Lopez, Philippe, Lupu, Cristina, Radnoti, Gabor, Rosnay, Patricia de, Rozum, Iryna, Vamborg, Freja, Villaume, Sebastien, and Thépaut, Jean-Noël, 2018, ERA5 hourly data on single levels from 1940 to present: Copernicus Climate Change Service (C3S) Climate Data Store (CDS), online.

   Online Links:

   • https://doi.org/10.24381/cds.adbb2d47

   Type_of_Source_Media: online database
   Source_Contribution: Reanalysis Forcing Data
   

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

   Date: 01-Jan-2024 (process 1 of 3)

   Regional scale data were created for the full Puget Sound region using a hydrodynamic, wave, and hydrologic model. All regional scale models were run for 3 periods: reanalysis (1940-2023), historic CMIP6 (1950–2015) and future CMIP6(2015-2050). Forcing for the reanalysis period was provided by the ERA5 dataset and by 7 CMIP6 models for the historic and future periods (HighResMIP, Haarsma and others, 2016). The Hydrodynamic Model (delft3d-FM) was used for simulating regional water levels and is detailed in Grossman and others, 2023. Waves were modelled using a SWAN lookup table with linear swell propagation as detailed in Crosby and others, 2023. In addition to winds, swell was added through the Strait of Juan de Fuca via modeled CMIP6 Waves and from data provided by ERA5. Hydrology was provided by a county level hydrological model detailed in Buitink and others, 2025. The hydrodynamic and wave models were additionally run for a variety of SLR positions (0, 25, 50, 100, 150, 200, 300 cm). Outputs were saved as station output across the full Puget Sound region, in the nearshore for wave and water level data and at a variety of elevation contours for hydrologic data. Data sources used in this process:

   • ERA5
   • Hydrodynamic Model
   • CMIP6 Waves

   Date: 01-Jan-2025 (process 2 of 3)

   A SFINCS model was developed following the methodology detailed in Nederhoff and others, 2025. The model was built using topographic/bathymetry data from a DEM and covered the full extent of King County. Models were forced with continuous oceanographic and hydrologic forcing (provided by the regional model) for 2 periods: a reanalysis period and future projection period. The reanalysis period was used for model validation and the projection period was used for producing CoSMoS hazard outputs. For the future projection period, the model was run continuously for 100 years at 6 SLR scenarios. Outputs of maximum water levels were saved for each simulation year. Data sources used in this process:

   • DEM

   Date: 01-Jul-2025 (process 3 of 3)

   All simulation data were downloaded from the USGS Advanced Research Computing Center’s Hovenweep Supercomputer (Falgout and others, 2024) to be post-processed. For each of the 6 SLR scenarios, the 1-, 10-, 20-, 50-, and 100-year return period hazard level was derived using empirical return intervals from the 100-year time series of annual max water levels. Output data (flood depth, water elevation, maximum depth x velocity, flood extent) were derived from the occurrence of the water level extreme. Flood depth and extent were post-processed with an attenuated bathtub to remove edge effects and therefore do not match the spatial extent of the other products. GeoTIFFs were created and bundled by county (Water_elevation_projections-King.zip). Data are organized by storm scenario (’RP’) and SLR magnitude.

3. What similar or related data should the user be aware of?
   Haarsma, R.J., Roberts, M.J., Vidale, P.L., Senior, C.A., Bellucci, A., Bao, Q., Chang, P., Corti, S., Fučkar, N.S., Guemas, V., Hardenberg, J. von, Hazeleger, W., Kodama, C., Koenigk, T., Leung, L. R., Lu, J., Luo, J.J., Mao, J., Mizielinski, M.S., Mizuta, R., Nobre, P., Satoh, M., Scoccimarro, E., Semmler, T., Small, J., and Storch, J.S. von, 2016, High resolution model intercomparison project (HighResMIP v1.0) for CMIP6.

   Online Links:

   • https://doi.org/10.5194/gmd-9-4185-2016

   Other_Citation_Details:

   Haarsma, R.J., Roberts, M.J., Vidale, P.L., Senior, C.A., Bellucci, A., Bao, Q., Chang, P., Corti, S., Fučkar, N.S., Guemas, V., von Hardenberg, J., Hazeleger, W., Kodama, C., Koenigk, T., Leung, L. R., Lu, J., Luo, J. J., Mao, J., Mizielinski, M.S., Mizuta, R., Nobre, P., Satoh, M., Scoccimarro, E., Semmler, T., Small, J., and von Storch, J.S., 2016, High Resolution Model Intercomparison Project (HighResMIP v1.0) for CMIP6: Geoscientific Model Development, vol. 9, p. 4185–4208, https://doi.org/10.5194/gmd-9-4185-2016, 2016.

   Grossman, Eric E., Tehranirad, Babak, Nederhoff, Kees, Crosby, Sean C., Stevens, Andrew W., Nathan R. Van Arendonk, Nowacki, Daniel J., Erikson, Li H., and Barnard, Patrick L., 2023, Modeling Extreme Water Levels in the Salish Sea: The Importance of Including Remote Sea Level Anomalies for Application in Hydrodynamic Simulations.

   Online Links:

   • https://doi.org/10.3390/w15234167

   Other_Citation_Details:

   Grossman, E. E., Tehranirad, B., Nederhoff, C. M., Crosby, S. C., Stevens, A. W., Van Arendonk, N. R., Nowacki D. J., Erikson, L. H., and Barnard, P. L. (2023). Modeling Extreme Water Levels in the Salish Sea: The Importance of Including Remote Sea Level Anomalies for Application in Hydrodynamic Simulations. Water, 15(23), 4167.

   Falgout, J.T., Gordon, J., Williams, B., and Davis, M.J., 2024, USGS Advanced Research Computing, USGS Denali Supercomputer..

   Online Links:

   • https://doi.org/10.5066/P9PSW367

   Other_Citation_Details:

   Falgout, J.T., Gordon J., Williams B., Davis M. J., USGS Advanced Research Computing, USGS Denali Supercomputer: U.S. Geological Survey, https://doi.org/10.5066/P9PSW367

   Crosby, Sean C., Nederhoff, Kees, VanArendonk, Nathan R., and Grossman, Eric E., 2023, Efficient modeling of wave generation and propagation in a semi-enclosed estuary.

   Online Links:

   • https://doi.org/10.1016/j.ocemod.2023.102231

   Other_Citation_Details:

   Crosby, S. C., Nederhoff, K., VanArendonk, N.R., and Grossman, E.E., 2023, Efficient modeling of wave generation and propagation in a semi-enclosed estuary: Ocean Modeling, https://doi.org/10.1016/j.ocemod.2023.102231.

   Nederhoff, Kees, Parker, Kai, and Grossman, Eric E., 2025, Beyond the 100-Year Flood: Probabilistic Flood Hazard Assessment for King and Pierce Counties under Future Climate Scenarios.

   Online Links:

   • https://doi.org/10.5194/egusphere-2025-4909

   Other_Citation_Details:

   Nederhoff, K., Parker, K., and Grossman, E., 2025, Beyond the 100-Year Flood: Probabilistic Flood Hazard Assessment for King and Pierce Counties under Future Climate Scenarios: EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-4909.

   Buitink, Joost, Dalmijn, Brendan, Parker, Kai, and Nederhoff, Kees, 2025, Wetter Winters, Drier Summers: Quantifying the change in hydrological response around the Puget Sound area using the wflow_sbm hydrological model and CMIP6 projections.

   Online Links:

   • https://doi.org/10.31223/X58R0G

   Other_Citation_Details:

   Buitink, J., Dalmijn, B., Parker, K.A., Nederhoff, K. and Grossman, E., 2025, Wetter Winters, Drier Summers: Quantifying the change in hydrological response around the Puget Sound area using the wflow_sbm hydrological model and CMIP6 projections: EarthArXiv [preprint], https://doi.org/10.31223/X58R0G.

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

1. How well have the observations been checked?
   Attribute values are model-derived water elevations (m, NAVD88) due to plausible sea-level rise and future storm conditions and therefore cannot be validated against observations. The projections were generated using the latest downscaled climate projections from the Coupled Model Intercomparison Project (CMIP6).
2. How accurate are the geographic locations?
   Data are concurrent with topobathymetric digital elevation model (DEM) locations.
3. How accurate are the heights or depths?
   Model-derived data are accurate within published uncertainty bounds, indicative of total uncertainty from elevation data sources and model processes. See Nederhoff and others, 2025 for additional information on vertical accuracy and uncertainty layer development.
4. Where are the gaps in the data? What is missing?
   Dataset is considered complete for the information presented.
5. How consistent are the relationships among the observations, including topology?
   Data have undergone quality checks and meet standards.

How can someone get a copy of the data set?

1. Who distributes the data set? (Distributor 1 of 1)
   
   U.S. Geological Survey - CMGDS

   2885 Mission Street

   Santa Cruz, CA
   

   831-427-4747 (voice)

   pcmsc_data@usgs.gov
2. What's the catalog number I need to order this data set? These data are available in GeoTIFF format contained in a single zip file with filenames of “Water_elevation_projections-King.zip” accompanied by CSDGM FGDC-compliant metadata.
3. What legal disclaimers am I supposed to read?
   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 (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
4. How can I download or order the data?
   • Availability in digital form:

     Data format:	Zip file contains GeoTIFF files for King County, WA in format GeoTIFF Size: 51.6
     Network links:	https://doi.org/10.5066/P13HYXKY

   • Cost to order the data: None.

5. What hardware or software do I need in order to use the data set?
   These data can be viewed with any spatial analysis software (for example, ArcGIS, QGIS, and so on)

Who wrote the metadata?

Dates:

Last modified: 26-Nov-2025

Metadata author:

U.S. Geological Survey, Pacific Coastal and Marine Science Center

Attn: PCMSC Science Data Coordinator

2885 Mission Street

Santa Cruz, CA

831-427-4747 (voice)

pcmsc_data@usgs.gov

Metadata standard:

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