Metadata: Identification_Information: Citation: Citation_Information: Originator: Kevin M. Befus Originator: Daniel J. Hoover Originator: Patrick L. Barnard Publication_Date: 20230315 Title: Projected groundwater head along the Virginia, Georgia, and Florida coasts Geospatial_Data_Presentation_Form: GeoTIFF Series_Information: Series_Name: data release Issue_Identification: DOI: 10.5066/P9BQQTCI Publication_Information: Publication_Place: Pacific Coastal and Marine Science Center Santa Cruz, California Publisher: U.S. Geological Survey Online_Linkage: https://doi.org/10.5066/P9BQQTCI Larger_Work_Citation: Citation_Information: Originator: Patrick L. Barnard Originator: Kevin Befus Originator: Jeffrey J. Danielson Originator: Anita C. Engelstad Originator: Li H. Erikson Originator: Amy C. Foxgrover Originator: Maya K. Hayden Originator: Daniel J. Hoover Originator: Tim Leijnse Originator: Chris Massey Originator: Robert McCall Originator: Norberto C. Nadal-Caraballo Originator: Kees Nederhoff Originator: Leonard O. Ohenhen Originator: Andrea C. O'Neill Originator: Kai A. Parker Originator: Manoocher Shirzaei Originator: Xin Su Originator: Jennifer A. Thomas Originator: Maarten van Ormondt Originator: Sean F. Vitousek Originator: Kilian Vos Originator: Madison C. Yawn Publication_Date: 2023 Title: Future coastal hazards along the U.S. Atlantic coast Series_Information: Series_Name: data release Issue_Identification: DOI: 10.5066/P9BQQTCI Publication_Information: Publication_Place: Pacific Coastal and Marine Science Center, Santa Cruz, CA Publisher: U.S. Geological Survey Online_Linkage: https://doi.org/10.5066/P9BQQTCI Description: Abstract: Seamless unconfined groundwater heads for U.S. coastal Virginia, Georgia, and Florida (Atlantic and Gulf coast south of Sarasota) groundwater systems were modeled with homogeneous, steady-state MODFLOW simulations. The geographic extent examined was limited primarily to low-elevation (land surface less than approximately 10 m above mean sea level) areas. Steady-state MODFLOW groundwater flow models were used to obtain detailed (50-meter-scale) predictions over large geographic scales (100s of kilometers) of groundwater heads for both current and future sea-level rise (SLR) scenarios (0, 0.25, 0.5, 1, 1.5, 2, 2.5, and 3 m) using 3 spatially varying hydraulic conductivities (K); one based on published K's, one with published K's reduced by a factor of 10 (K*0.1), and one with published K's increased by a factor of 10 (K*10) to assess the sensitivity of model results to K. All models had variable thicknesses corresponding to published transmissivities. The models were run with a local mean higher-high water (MHHW) marine boundary condition and with groundwater reaching the land surface removed from the model, simulating loss via natural drainage. Similar modeled data for North Carolina and South Carolina are available from Barnard and others, 2023 at https://doi.org/10.5066/P9W91314. Purpose: 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. Supplemental_Information: This data release was funded by the USGS Coastal and Marine Hazards and Resources Program. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1985 Ending_Date: 2023 Currentness_Reference: oldest dataset used through year of publication Status: Progress: Complete Maintenance_and_Update_Frequency: None Planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -82.499627 East_Bounding_Coordinate: -75.203445 North_Bounding_Coordinate: 38.027919 South_Bounding_Coordinate: 25.098211 Keywords: Theme: Theme_Keyword_Thesaurus: USGS Metadata Identifier Theme_Keyword: USGS:78d578b9-fc5d-4aaa-8de0-951061500a23 Theme: Theme_Keyword_Thesaurus: Data Categories for Marine Planning Theme_Keyword: Physical Habitats and Geomorphology Theme: Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD) Theme_Keyword: Hazards Planning Theme_Keyword: Beaches Theme_Keyword: Sea Level Rise Theme_Keyword: Floods Theme_Keyword: Water Depth Theme: Theme_Keyword_Thesaurus: USGS Thesaurus Theme_Keyword: Climate Change Theme_Keyword: Floods Theme_Keyword: Groundwater Flow Theme_Keyword: Sea-level Change Theme_Keyword: mathematical modeling Theme_Keyword: effects of climate change Theme_Keyword: earth sciences Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: Oceans Theme_Keyword: GeoscientificInformation Theme_Keyword: InlandWaters Theme: Theme_Keyword_Thesaurus: Marine Realms Information Bank (MRIB) keywords Theme_Keyword: sea level change Theme_Keyword: floods Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: U.S. Geological Survey Theme_Keyword: USGS Theme_Keyword: Coastal and Marine Hazards and Resources Program Theme_Keyword: CMHRP Theme_Keyword: Pacific Coastal and Marine Science Center Theme_Keyword: PCMSC Place: Place_Keyword_Thesaurus: Geographic Names Information System Place_Keyword: State of Virginia Place_Keyword: State of Georgia Place_Keyword: State of Florida 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 Arkansas as the originators of the dataset and in products derived from these data. This information is not intended for navigation purposes. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey, Pacific Coastal and Marine Science Center Contact_Person: PCMSC Science Data Coordinator Contact_Address: Address_Type: mailing and physical Address: 2885 Mission Street City: Santa Cruz State_or_Province: CA Postal_Code: 95060-5792 Country: US Contact_Voice_Telephone: 831-460-4747 Contact_Facsimile_Telephone: 831-427-4748 Contact_Electronic_Mail_Address: pcmsc_data@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: GWHazards_GWHead_browse_graphic.png Browse_Graphic_File_Description: Map showing groundwater head results along the coasts of Virginia, Georgia, and Florida for the K x 1 and present-day sea-level rise (0m) scenario. Colors represent groundwater head (elevation) relative to the NAVD88 vertical datum. Browse_Graphic_File_Type: PNG Cross_Reference: Citation_Information: Originator: Patrick L. Barnard Originator: Kevin Befus Originator: Jeffrey J. Danielson Originator: Anita C. Engelstad Originator: Li H. Erikson Originator: Amy C. Foxgrover Originator: Matthew W. Hardy Originator: Daniel J. Hoover Originator: Tim Leijnse Originator: Chris Massey Originator: Robert McCall Originator: Norberto C. Nadal-Caraballo Originator: Kees Nederhoff Originator: Leonard Ohenhen Originator: Andrea C. O'Neill Originator: Kai A. Parker Originator: Manoocher Shirzaei Originator: Xin Su Originator: Jennifer A. Thomas Originator: Maarten van Ormondt Originator: Sean F. Vitousek Originator: Kilian Vos Originator: Madison C. Yawn Publication_Date: 2023 Title: Future coastal hazards along the U.S. North and South Carolina coasts Other_Citation_Details: Barnard, P.L., Befus, K., Danielson, J.J., Engelstad, A.C., Erikson, L.H., Foxgrover, A.C., Hardy, M.W., Hoover, D.J., Leijnse, T., Massey, C., McCall, R., Nadal-Caraballo, N.C., Nederhoff, K., Ohenhen, L., O'Neill, A.C., Parker, K.A., Shirzaei, M., Su, X., Thomas, J.A., van Ormondt, M., Vitousek, S.F., Vos K., and Yawn, M.C., 2023, Future coastal hazards along the U.S. North and South Carolina coasts: U.S. Geological Survey data release, https://doi.org/10.5066/P9W91314. Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Attribute values are model-derived groundwater heads for present-day and future sea-level rise conditions. The model uses parameters from calibrated and published groundwater models and is intended to show the general response of the shallow coastal water table to sea-level rise. Projected heads for future sea-level rise conditions cannot be validated against observations. Logical_Consistency_Report: Data have undergone quality checks and meet standards. Completeness_Report: Dataset is considered complete for the information presented. Users are advised to read the metadata record carefully for additional details. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Data are concurrent with topographic digital elevation model (DEM) locations. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Model-derived head elevations are accurate within the limitations of the model. The model uses parameters from calibrated, published groundwater models, but limitations due to model resolution and uncertainty in model parameter values may significantly affect modeled head elevations. As a result, model results are intended to show only the general response of the shallow coastal water table to sea-level rise. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: M. Reitz Originator: W. E. Sanford Originator: G. B. Senay Originator: J. Cazenas Publication_Date: 2017 Title: Annual estimates of recharge, quick-flow runoff, and evapotranspiration for the contiguous US using empirical regression equations Geospatial_Data_Presentation_Form: raster Publication_Information: Publication_Place: online Publisher: Journal of the American Water Resources Association Online_Linkage: https://doi.org/10.1111/1752-1688.12546 Type_of_Source_Media: digital dataset Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 2000 Ending_Date: 2013 Source_Currentness_Reference: oldest dataset used through newest Source_Citation_Abbreviation: recharge Source_Contribution: Digital recharge data used for model input. Users are advised to read the published paper and metadata for this source dataset carefully. Source_Information: Source_Citation: Citation_Information: Originator: Wesley O. Zell Originator: Ward E. Sanford Publication_Date: 2020 Title: Calibrated simulation of the long-term average surficial groundwater system and derived spatial distributions of its characteristics for the contiguous United States Geospatial_Data_Presentation_Form: raster Publication_Information: Publication_Place: online Publisher: Water Resources Research Online_Linkage: https://doi.org/10.1029/2019WR026724 Type_of_Source_Media: digital dataset Source_Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1985 Ending_Date: 2015 Source_Currentness_Reference: oldest dataset used through newest Source_Citation_Abbreviation: Zell K and Head model thickness Source_Contribution: Digital hydraulic conductivity (K) and associated model thickness data used for model input. Users are advised to read the published paper and metadata for this source dataset carefully. Process_Step: Process_Description: Built MODFLOW (MODFLOW-NWT-SWR1 v1.2.0; https://www.usgs.gov/software/modflow-nwt-newton-formulation-modflow-2005) groundwater models for the model domain. Process_Date: 20210803 Process_Step: Process_Description: Ran MODFLOW models to obtain groundwater heads. Source_Used_Citation_Abbreviation: recharge Process_Date: 20210915 Process_Step: Process_Description: Revised MODFLOW models to use original Zell and Sanford (2020) model thicknesses and revised merging sequence. Source_Used_Citation_Abbreviation: Zell K and Head model thickness Process_Date: 20211218 Process_Step: Process_Description: Reran MODFLOW models, revising merging sequence again to eliminate artifacts associated with first tiling data and then merging tiles to State products. Process_Date: 20220305 Process_Step: Process_Description: Set FL non-convergent cell results to NaN to remove high outliers. Process_Date: 20220405 Process_Step: Process_Description: Edits were made to correct spelling in author name. No data were changed. The metadata available from a harvester may supersede metadata bundled within a download file. Users are advised to compare the metadata date of this file to any similar file to ensure they are using the most recent version. (scochran@usgs.gov) Process_Date: 20230516 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: pixel Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 17 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -81.000000 Latitude_of_Projection_Origin: 0.000000 False_Easting: 500000.000000 False_Northing: 0.000000 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: row and column Coordinate_Representation: Abscissa_Resolution: 50.000000 Ordinate_Resolution: 50.000000 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: GCS WGS 1984 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257224 Vertical_Coordinate_System_Definition: Depth_System_Definition: Depth_Datum_Name: NAVD88 Depth_Resolution: 0.001 Depth_Distance_Units: meters Depth_Encoding_Method: Implicit coordinate Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: projected coastal groundwater head Entity_Type_Definition: Geotiffs of projected coastal groundwater head for the State, SLR, and K case specified Entity_Type_Definition_Source: originators at United States Geological Survey, Pacific Coastal and Marine Science Center Attribute: Attribute_Label: Projection of coastal groundwater head for given State, SLR, and K case specified Attribute_Definition: Groundwater head Attribute_Definition_Source: model determined Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -0.064 Range_Domain_Maximum: 62.131 Attribute_Units_of_Measure: meters Attribute_Measurement_Resolution: 0.001 Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey - CMGDS Contact_Address: Address_Type: mailing and physical Address: 2885 Mission Street City: Santa Cruz State_or_Province: CA Postal_Code: 95060 Country: USA Contact_Voice_Telephone: 831-427-4747 Contact_Electronic_Mail_Address: pcmsc_data@usgs.gov Resource_Description: Zip files (GWHazards_GWHead_statename_Kx0p1.zip, GWHazards_GWHead_statename_Kx1.zip, GWHazards_GWHead_statename_Kx10.zip) contain groundwater head projections for all 8 SLR cases for the State and hydraulic conductivity (K) indicated. When unzipped, individual groundwater head files have filenames with the structure "(St_abbrev)_Kzell(K#)_slr(SLR#)m_50m_head.tif", where St_abbrev is the abbreviated State name (VA, GA, FL), K# is 0p1, 1, or 10, and SLR# is 0p00, 0p25, 0p50, 1p00, 1p50, 2p00, 2p50, or 3p00. The "p" in file names is used in place of a decimal point. File sizes are in MB. Distribution_Liability: 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. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_VA_Kx0p1.zip) includes 8 GeoTIFF files for coastal Virginia, K x 0.1 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 507.4 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_VA_Kx1.zip) includes 8 GeoTIFF files for coastal Virginia, K x 1 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 506.8 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_VA_Kx10.zip) includes 8 GeoTIFF files for coastal Virginia, K x 10 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 503.8 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_GA_Kx0p1.zip) includes 8 GeoTIFF files for coastal Georgia, K x 0.1 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 294.0 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_GA_Kx1.zip) includes 8 GeoTIFF files for coastal Georgia, K x 1 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 293.1 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_GA_Kx10.zip) includes 8 GeoTIFF files for coastal Georgia, K x 10 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 291.3 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_FL_Kx0p1.zip) includes 8 GeoTIFF files for coastal Florida, K x 0.1 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 1600 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_FL_Kx1.zip) includes 8 GeoTIFF files for coastal Florida, K x 1 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 1600 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: ArcGIS 10.5 Format_Specification: Features are GeoTIFF format and are projected in UTM Zone 17 coordinates, with horizontal datum WGS84 and vertical datum NAVD88. Format_Information_Content: The .zip file (GWHazards_GWHead_FL_Kx10.zip) includes 8 GeoTIFF files for coastal Florida, K x 10 hydraulic conductivities, for SLRs of 0, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0m. File_Decompression_Technique: WinZip Transfer_Size: 1600 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.5066/P9BQQTCI Access_Instructions: Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. Fees: none Metadata_Reference_Information: Metadata_Date: 20230516 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey, Pacific Coastal and Marine Science Center Contact_Person: PCMSC Science Data Coordinator Contact_Address: Address_Type: mailing and physical Address: 2885 Mission Street City: Santa Cruz State_or_Province: CA Postal_Code: 95060-5792 Country: US Contact_Voice_Telephone: 831-460-4747 Contact_Facsimile_Telephone: 831-427-4748 Contact_Electronic_Mail_Address: pcmsc_data@usgs.gov Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998