Projected groundwater emergence and shoaling for coastal California using present-day and future sea-level rise scenarios

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Frequently anticipated questions:

What does this data set describe?

Title:
Projected groundwater emergence and shoaling for coastal California using present-day and future sea-level rise scenarios
Abstract:
Seamless unconfined groundwater heads for coastal California groundwater systems were modeled with homogeneous, steady-state MODFLOW simulations. The geographic extent examined was limited primarily to low-elevation (i.e. land surface less than approximately 10 m above mean sea level) areas. In areas where coastal elevations increase rapidly (e.g., bluff stretches), the model boundary was set approximately 1 kilometer inland of the present-day shoreline. Steady-state MODFLOW groundwater flow models were used to obtain detailed (10-meter-scale) predictions over large geographic scales (100s of kilometers) of groundwater heads for both current and future sea-level rise (SLR) scenarios (0 to 2 meters (m) in 0.25 m increments, 2.5 m, 3 m, and 5 m) using a range of horizontal hydraulic conductivity (Kh) scenarios (0.1, 1, and 10 m/day). For each SLR/Kh combination, results are provided for two marine boundary conditions, local mean sea level (LMSL) and mean higher-high water (MHHW), and two model versions. In the first model version, groundwater reaching the land surface is removed from the model, simulating loss via natural drainage. In the second model version, groundwater reaching the land surface is retained, simulating the worst-case "linear" response of groundwater head to sea-level rise. Modeled groundwater heads were then subtracted from high-resolution topographic digital elevation model (DEM) data to obtain the water table depths, which are represented as polygons for specific depth ranges in this dataset. Additional details about the groundwater model and data sources are outlined in Befus and others (2020) and in Groundwater_model_methods.pdf (available at https://www.sciencebase.gov/catalog/file/get/5b8ef008e4b0702d0e7ec72b?name=Groundwater_model_methods.pdf). Methods specific to groundwater head and water table depth products are outlined in Groundwater_head_and_water_table_depth_methods.pdf (available at https://www.sciencebase.gov/catalog/file/get/5bda1563e4b0b3fc5cec39b4?name=Groundwater_head _and_water_table_depth_methods.pdf). Methods specific to groundwater emergence and shoaling products are outlined in Groundwater_emergence_and_shoaling_methods.pdf (available at https://www.sciencebase.gov/catalog/file/get/5bd9f318e4b0b3fc5cec20ed?name=Groundwater_emergence_and_shoaling_methods.pdf). Please read the model details, data sources and methods summaries and inspect model output carefully. Data are complete for the information presented. Users should note that while the metadata Spatial Reference Information/UTM Zone Number in this document is 10, some files in southern California are in UTM Zone 11, as noted in the Format Specification for individual downloadable files. As a result users may need to modify the metadata for automated import and display of Zone 11 datafiles.
Supplemental_Information:
This work is one portion of ongoing CoSMoS modeling efforts for California and the western United States. For information on CoSMoS data sources and details on methodology, see https://www.sciencebase.gov/catalog/file/get/5633fea2e4b048076347f1cf?name=CoSMoS_SoCalv3_Phase2_summary_of_methods.pdf. For more information on CoSMoS, see https://www.usgs.gov/centers/pcmsc/science/coastal-storm-modeling-system-cosmos
  1. How might this data set be cited?
    Befus, Kevin M., Hoover, Daniel J., Barnard, Patrick L., and Erikson, Li H., 20200811, Projected groundwater emergence and shoaling for coastal California using present-day and future sea-level rise scenarios: data release DOI:10.5066/P9H5PBXP, U.S. Geological Survey, Pacific Coastal and Marine Science Center Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Befus, Kevin M., Hoover, Daniel, Barnard, Patrick L., and Erikson, Li H., 2020, Projected responses of the coastal water table for California using present-day and future sea-level rise scenarios: data release DOI:10.5066/P9H5PBXP, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -124.478284
    East_Bounding_Coordinate: -117.013591
    North_Bounding_Coordinate: 42.007837
    South_Bounding_Coordinate: 32.512823
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5b8ef008e4b0702d0e7ec72b?name=groundwater_model_map.png&allowOpen=true (PNG)
    Map of groundwater modeling coverage
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Jan-2008
    Ending_Date: 2020
    Currentness_Reference:
    oldest dataset used through year of publication
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: polygon shapefile
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set.
    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: 0.999600
      Longitude_of_Central_Meridian: -100.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 10.000000
      Ordinates (y-coordinates) are specified to the nearest 10.000000
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum 1983 (NSRS2007).
      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.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: NAVD88
      Depth_Resolution: 1.0
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?
    projected water table depths
    shapefiles of projected water table depths for the California County, marine boundary condition (MHHW or LMSL), SLR, and Kh case specified, including "linear" head response (no removal of groundwater reaching the ground surface) for each scenario (Source: originators at United States Geological Survey, Pacific Coastal and Marine Science Center)
    fbin_m
    Depth range code (Source: producer defined)
    ValueDefinition
    0emergent
    10 to 1 meter
    21 to 2 meters
    52 to 5 meters
    6deeper than 5 meters

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Kevin M. Befus
    • Daniel J. Hoover
    • Patrick L. Barnard
    • Li H. Erikson
  2. Who also contributed to the data set?
  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
    US

    831-460-4747 (voice)
    831-427-4748 (FAX)
    pcmsc_data@usgs.gov

Why was the data set created?

Projections for future sea-level rise provide emergency responders and coastal planners with critical hazards information that can be used to increase public safety, mitigate physical damages, and more effectively manage and allocate resources within complex coastal settings. These data are intended for policy makers, resource managers, science researchers, students, and the general public. These data can be used with geographic information systems or other software to identify and assess possible areas of vulnerability. These data are not intended to be used for navigation.

How was the data set created?

  1. From what previous works were the data drawn?
    water table depth (source 1 of 1)
    Befus, Kevin M., Hoover, Daniel J., Barnard, Patrick L., and Erikson, Li H., 2020, Projected water table depths for coastal California using present-day and future sea-level rise scenarios: U.S. Geological Survey, online.

    Online Links:

    Type_of_Source_Media: digital dataset
    Source_Contribution: raster depths that were converted to polygons
  2. How were the data generated, processed, and modified?
    Date: Jan-2020 (process 1 of 3)
    Using water table depth raster data, a polygon shapefile was created for water table depths in specific depth ranges (emergent, 0-1m, 1-2m, 2-5m, >5m). See Groundwater_emergence_and_shoaling_methods.pdf, available with this data release, for additional information. Data sources used in this process:
    • water table depth
    Date: 19-Oct-2020 (process 2 of 3)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 13-Oct-2021 (process 3 of 3)
    Performed minor edits to the metadata to correct typos. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A. Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Befus, Kevin M., Barnard, Patrick L., Hoover, Daniel J., Finzi, Juliette A. Hart, and Voss, C., 2020, Increasing threat of coastal groundwater hazards from sea-level rise.

    Online Links:

    Other_Citation_Details:
    Befus, K.M., Barnard, P.L., Hoover, D.J., Finzi Hart, J.A., and Voss, C., 2020, Increasing threat of coastal groundwater hazards from sea-level rise: Nature Climate Change, https://doi.org/10.1038/s41558-020-0874-1

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 table depths for present-day and future sea-level rise conditions. The model is intended to show the general response of the shallow coastal water table to sea level rise, and data were not available to constrain subsurface geology or the marine boundary condition, so the model uses a plausible range of horizontal hydraulic conductivities (Kh = 0.1, 1 and 10 m/day) and marine boundary conditions (local mean sea level (LMSL) and mean higher-high water (MHHW) to bracket reasonable model parameter values. Modeled present-day water tables have been validated by comparison to available data (see Groundwater_head_and_water_table_depth_methods.pdf). Projected water tables for future sea-level rise conditions cannot be validated against observations.
  2. How accurate are the geographic locations?
    Data are concurrent with topographic digital elevation model (DEM) locations.
  3. How accurate are the heights or depths?
    Model-derived data are accurate within the limitations outlined in Groundwater_model_methods.pdf, Groundwater_head_and_water_table_depth_methods.pdf, and Groundwater_emergence_and_shoaling_methods.pdf, all of which are available as part of this data release.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented (as described in the Methods documents). Users are advised to read the metadata record and Methods documents carefully for additional details.
  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?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey and the University of Wyoming as the originators of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? File (countyname_LMSL.ZIP or countyname_MHHW_zip) contains water table depth projections for the California County, marine boundary condition (MBC), sea-level rise (SLR) and horizontal hydraulic conductivity (Kh) indicated, and for "linear" depth to groundwater (no removal of groundwater reaching the ground surface) for each MBC/Kh/SLR case.
  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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2021
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA
US

831-460-4747 (voice)
831-427-4748 (FAX)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P9H5PBXP/Groundwater_emergence_shoaling_metadata.faq.html>
Generated by mp version 2.9.50 on Thu Oct 14 14:47:22 2021