Metadata:
  Identification_Information:
    Citation:
      Citation_Information:
        Originator: Jessica D. DeWitt
        Originator: Peter G. Chirico
        Originator: Sarah E. Bergstresser
        Publication_Date: 2018
        Title: The Central African Republic Diamond Database (2018) - Hydrologically Corrected Digital Elevation Model (30 m)
        Geospatial_Data_Presentation_Form: GIS dataset
        Publication_Information:
          Publication_Place: Reston, VA
          Publisher: U.S. Geological Survey
        Online_Linkage: https://doi.org/10.5066/F7ZG6R3V
        Larger_Work_Citation:
          Citation_Information:
            Originator: Jessica D. DeWitt
            Originator: Peter G. Chirico
            Originator: Sarah G. Bergstresser
            Originator: Inga E. Clark
            Publication_Date: 2018
            Title: The Central African Republic Diamond Database – A Geodatabase of Archival Diamond Occurrences and Areas of Recent Artisanal and Small-scale Diamond Mining
            Geospatial_Data_Presentation_Form: On File Report
            Publication_Information:
              Publication_Place: Reston, VA
              Publisher: U.S. Geological Survey
    Description:
      Abstract: This is a 30 m digital elevation model (DEM) raster that was created by post-processing and hydrologically correcting the Shuttle Radar Topography Mission (SRTM) 30 m DEM. Procedures to create the DEM included mosaicking of multiple 30 m SRTM tiles, reprojection into UTM 34 N WGS 84 planar projection, an averaging filter to smooth out local variance in elevation values, conversion to float type, and improvements to hydrologic flow following the methods of Hellweger and Maidment (1997). For a complete description of the procedures used to create the DEM, see DeWitt and others (2018).
      Purpose: The purpose of this dataset is to model the physical topography of the Central African Republic (CAR) in a regular grid-format. The GIS raster dataset describes elevation values in meters (m) above sea level.
      Supplemental_Information: This dataset is closely associated with the Central African Republic Diamond Database (2018) - Hillshade dataset (30 m), published as part of the same On File Report.
    Time_Period_of_Content:
      Time_Period_Information:
        Single_Date/Time:
          Calendar_Date: 2018
      Currentness_Reference: publication date
    Status:
      Progress: Complete
      Maintenance_and_Update_Frequency: None planned
    Spatial_Domain:
      Bounding_Coordinates:
        West_Bounding_Coordinate: 14.392089839578
        East_Bounding_Coordinate: 27.487792964054
        North_Bounding_Coordinate: 11.005474976683
        South_Bounding_Coordinate: 2.3280232001808
    Keywords:
      Theme:
        Theme_Keyword_Thesaurus: USGS Thesaurus
        Theme_Keyword: digital elevation model (DEM)
      Place:
        Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
        Place_Keyword: Central African Republic
    Access_Constraints: none
    Use_Constraints: Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
    Point_of_Contact:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Jessica D. DeWitt
          Contact_Organization: U.S. Geological Survey
        Contact_Address:
          Address_Type: mailing and physical
          Address: 12201 Sunrise Valley Dr.
          City: Reston
          State_or_Province: VA
          Postal_Code: 20170
          Country: USA
        Contact_Voice_Telephone: 703-648-6926
        Contact_Electronic_Mail_Address: jdewitt@usgs.gov
  Data_Quality_Information:
    Attribute_Accuracy:
      Attribute_Accuracy_Report: No formal attribute accuracy tests were conducted
    Logical_Consistency_Report: No formal logical accuracy tests were conducted
    Completeness_Report: Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
    Positional_Accuracy:
      Horizontal_Positional_Accuracy:
        Horizontal_Positional_Accuracy_Report: No formal positional accuracy tests were conducted
      Vertical_Positional_Accuracy:
        Vertical_Positional_Accuracy_Report: No formal positional accuracy tests were conducted
    Lineage:
      Process_Step:
        Process_Description: Download of raw SRTM 30 m tiles covering the full extent of the Central African Republic (CAR) from the USGS Earth Explorer website (https://earthexplorer.usgs.gov).
        Process_Date: 2016
      Process_Step:
        Process_Description: All SRTM tiles were mosaicked into one continuous raster dataset (30 m) then reprojected from the WGS 84 geographic coordinate system into the Universal Transverse Mercator (UTM) projected coordinate system (zone 34 N, WGS 84) in PCI Geomatica OrthoEngine (v. 2014) software.
        Process_Date: 2016
      Process_Step:
        Process_Description: Focal average statistics were calculated for a 5x5 window to smooth local variation from the raster, and the raster was converted from integer to float type using ESRI ArcGIS (v.10.4).
        Process_Date: 201607
      Process_Step:
        Process_Description: Because the SRTM was created from radar data which is affected by dense vegetation, the thick canopy and undergrowth that grows in the stream valleys of CAR causes anomalously high elevation values in these areas and interferes with hydrologic flow. To resolve this issue, the major rivers of CAR were manually digitized as a new vector shapefile from the ESRI imagery basemap (ESRI, 2015) at scales 1:50,000 or coarser. This polyline file was converted to a 30 m raster with negative values, then used to vertically offset the pre-processed DEM and improve the modeling of hydrologic flow. These procedures roughly follow the the methods of Hellweger and Maidment (1997).
        Process_Date: 2017
  Spatial_Data_Organization_Information:
    Indirect_Spatial_Reference: Central African Republic
    Direct_Spatial_Reference_Method: Raster
  Spatial_Reference_Information:
    Horizontal_Coordinate_System_Definition:
      Planar:
        Map_Projection:
          Map_Projection_Name: Transverse Mercator
          Transverse_Mercator:
            Scale_Factor_at_Central_Meridian: 0.9996
            Longitude_of_Central_Meridian: 21.0
            Latitude_of_Projection_Origin: 0.0
            False_Easting: 500000.0
            False_Northing: 0.0
        Planar_Coordinate_Information:
          Planar_Coordinate_Encoding_Method: row and column
          Coordinate_Representation:
            Abscissa_Resolution: 30.0
            Ordinate_Resolution: 30.0
          Planar_Distance_Units: METERS
      Geodetic_Model:
        Horizontal_Datum_Name: D_WGS_84
        Ellipsoid_Name: WGS_1984
        Semi-major_Axis: 6378137.0
        Denominator_of_Flattening_Ratio: 298.257223563
  Entity_and_Attribute_Information:
    Overview_Description:
      Entity_and_Attribute_Overview: The dataset is an example of a DEM
      Entity_and_Attribute_Detail_Citation: Environmental Systems Research Institute (ESRI). ESRI Support GIS Dictionary. (June 26, 2017). http://support.esri.com/other-resources/gis-dictionary.
  Distribution_Information:
    Distributor:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Jessica D. DeWitt
          Contact_Organization: U.S. Geological Survey
        Contact_Address:
          Address_Type: mailing and physical
          Address: 12201 Sunrise Valley Dr.
          City: Reston
          State_or_Province: VA
          Postal_Code: 20192
          Country: USA
        Contact_Voice_Telephone: 7003-648-6926
        Contact_Electronic_Mail_Address: jdewitt@usgs.gov
    Distribution_Liability: Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
    Technical_Prerequisites: This dataset is formatted as a .tif raster. It requires the user to have geospatial software such as ESRI ArcGIS, Blue Marble Global Mapper, Que GIS, GRASS, or other GIS software.
  Metadata_Reference_Information:
    Metadata_Date: 20180405
    Metadata_Contact:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Jessica D. DeWitt
          Contact_Organization: U.S. Geological Survey
        Contact_Address:
          Address_Type: mailing and physical
          Address: 12201 Sunrise Valley Dr.
          City: Reston
          State_or_Province: VA
          Postal_Code: 20192
          Country: USA
        Contact_Voice_Telephone: 703-648-6926
        Contact_Electronic_Mail_Address: jdewitt@usgs.gov
    Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
    Metadata_Standard_Version: FGDC-STD-001-1998
