The Central African Republic Diamond Database (2018) - Hydrologically Corrected Digital Elevation Model (30 m)

Identification_Information:

Citation:

Citation_Information:

Originator: Jessica D. DeWitt
Originator: Peter G. Chirico
Originator: Sarah E. Bergstresser
Publication_Date: 2018
Title:

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

The Central African Republic Diamond Database (2018) - Hydrologically Corrected Digital Elevation Model (30 m)

Metadata: