The Central African Republic Diamond Database (2018) - Recent (2013-2017) Mining Activity Dataset

Identification_Information:

Citation:

Citation_Information:

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

Geospatial_Data_Presentation_Form: GIS data
Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Online_Linkage: https://doi.org/10.5066/F7GF0SDB
Larger_Work_Citation:

Citation_Information:

Originator: Jessica D. DeWitt
Originator: Peter G. Chirico
Originator: Sarah E. 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:

894 very-high resolution satellite images were acquired between January 2013 and December of 2016, covering nearly 60,000 km2 of the country. Of this total, 49% (437 images) were acquired for the Western CAR region and cover approximately half of the Carnot sandstone area (43,097 km2). The remaining 51% (457 images) cover specific parts of the Eastern CAR region, including several areas of the Mouka-Ouadda sandstone (26,540 km2). The acquired imagery was collected on 97 different dates between 2013 and 2017, with the majority of these dates occurring from 2015-2017. Interpretation of ASM activity was based on indicators of mining activity suggested in Chirico and Malpeli (2013) and Kauffman and others (2015). In the dataset published here, if any imagery indicators of mining activity were observed, including bright soil indicating excavation activity, a lack of vegetation surrounding the immediate area, sharp angularity in the sides of the pit, or the presence of turbid water in a pit, the site was considered active. The presence of multiple active mine sites within 1 square kilometer is recorded as an attribute with each point. The type of mining activity (whether generic, excavation, washing, or previously active) is also recorded in the attributes of each point. It should be noted that this dataset is not an exhaustive record of mining activity in CAR -- it is possible that there are artisanal mine sites beyond the extent of these points, however the dataset is complete to the extent of the satellite imagery and fieldwork observations available at this time. Additional information regarding the coverage of imagery, the methods of interpretation, and specific findings can be found in the Open-File Report that publishes this and associated datasets (DeWitt and others, 2018).

Purpose:

The purpose of this dataset is to catalog the geographic areas of active small-scale and artisanal diamond mining sites in the Central African Republic that have been interpreted from very high resolution (VHR) satellite imagery between the dates of January 1, 2013 and November 29, 2017.

Supplemental_Information:

A second dataset, titled "The Central African Republic Diamond Database (2018) - Archival ASM and Diamond Occurrences Dataset" is closely associated with this dataset, and should also be used in describing the geographic distribution of CAR's diamond resources

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 2013
Ending_Date: 2017

Currentness_Reference: ground condition

Status:

Progress: Complete
Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: 14.414062495844
East_Bounding_Coordinate: 27.421874995324
North_Bounding_Coordinate: 11.070173525592
South_Bounding_Coordinate: 2.3499775496997

Keywords:

Theme:

Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: gem resources
Theme_Keyword: placer deposit mining

Theme:

Theme_Keyword_Thesaurus: CommonGeographicAreas
Theme_Keyword: Central African Republic

Theme:

Theme_Keyword_Thesaurus: LithClass6.2
Theme_Keyword: Alluvium

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: Peter G. Chirico
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: 703-648-6950
Contact_Electronic_Mail_Address: pchirico@usgs.gov

Data_Set_Credit:

U.S. Department of State, U.S. Agency for International Development

Cross_Reference:

Citation_Information:

Originator: Jessica D. DeWitt
Originator: Peter G. Chirico
Originator: Sarah E. 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

Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

The accuracy of the mining interpretation within the Carnot region was assessed through comparison to field data collected by the U.S. Agency for International Development (USAID)’s Property Rights and Artisanal Diamond Development II (PRADD II) project. Between August 1, 2016 and January 30, 2017 the PRADD II project staff visited and mapped many artisanal mining sites throughout the Carnot region. Of the 262 points independently collected by this mapping endeavor, 65 field sites fell within or immediately adjacent to gridcells selected as suitable for current mining in the Recent Mining Activities Dataset and were used to assess the dataset’s accuracy (Figure 5). The comparison of these field observations with the Recent Mining Dataset is done using a confusion matrix. The Recent (2013-2016) Mining activity dataset was found to have an overall accuracy of 75% when compared to field observations collected by the PRADD II project. For more details regarding the accuracy assessment of this dataset, see DeWitt and others (2017).

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:

The Central African Republic - Archival Diamond Occurrence Dataset was used to identify geographic areas known for diamond mining activity within CAR. The extent of these sites were then designated as areas of interest, and analyzed through manual interpretation of high resolution satellite imagery to identify areas of recent mining activity. Very high resolution (VHR) satellite imagery with a ground sampling distance (GSD) of 2 m2 or less was acquired between January 1, 2015 and March 15, 2016. Although the entirety of the Carnot and Mouka-Ouadda focus areas were not able to be covered by VHR satellite imagery, areas known to be diamondiferous (particularly within the Mouka-Ouadda) were identified and prioritized using the Archival Diamond Occurrence dataset. Indicators used to visually interpret recent diamond mining activity from satellite imagery consisted of: the brightness of soil surrounding pits that indicate excavation activity, sharp angularity of pit edges indicating benching or recent excavation, the absence of vegetation surrounding the immediate area of the pit, and the presence and color of water in a pit. Additional details about satellite interpretation specific to the Carnot or the Mouka-Ouadda regions are provided in DeWitt and others (2017). Sites interpreted as having recent (2013-2016) mining activity were joined to a grid of 1 square kilometer (1 km2) polygons, and only gridcells containing points were kept in the Recent (2013-2016) Mining Activity Dataset. Thus each point in this dataset describes the centroid of a 1 square kilometer (1 km2) area, which contains one or more active small-scale mining sites. Where multiple mining activity types were present within a single cell, the cell was given the ASM_Value of 1 to generically indicate that mining activity was present.

Process_Date: 2016

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Point

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: coordinate pair
Coordinate_Representation:

Abscissa_Resolution: 10.0
Ordinate_Resolution: 10.0

Planar_Distance_Units: METERS

Geodetic_Model:

Horizontal_Datum_Name: D_WGS_1984
Ellipsoid_Name: WGS 1984
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257223563

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: Recent_mining_1km2_areas_2013_2016
Entity_Type_Definition:

locations of ASM activity interpreted from high resolution satellite imagery

Entity_Type_Definition_Source: USGS Artisanal Diamonds Project

Attribute:

Attribute_Label: OBJECTID
Attribute_Definition: Unique identification number for each point record
Attribute_Definition_Source: Automatically populated by ESRI ArcGIS 10.4
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 1815

Attribute:

Attribute_Label: Shape
Attribute_Definition: Geometry of the GIS data record
Attribute_Definition_Source: ESRI ArcGIS 10.4
Attribute_Domain_Values:

Unrepresentable_Domain: All records in this dataset are 'point' shapes.

Attribute:

Attribute_Label: ASM_Val
Attribute_Definition:

Type of artisanal and small-scale mining (ASM) activity observed in satellite imagery at a mine site.

Attribute_Definition_Source: USGS Artisanal Diamonds Project
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 1
Enumerated_Domain_Value_Definition: Site has mining activity (generic)
Enumerated_Domain_Value_Definition_Source: USGS Artisanal Diamonds Project

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2
Enumerated_Domain_Value_Definition:

Primarily excavation activity (signs of active digging, including benching, angular pit sides, and spoil piles)

Enumerated_Domain_Value_Definition_Source: USGS Artisanal Diamonds Project

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 3
Enumerated_Domain_Value_Definition: Washing of gravel material in pits or other nearby water body
Enumerated_Domain_Value_Definition_Source: USGS Artisanal Diamonds Project

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 5
Enumerated_Domain_Value_Definition:

Site is currently inactive based on image indicators (see DeWitt and others, 2017), but exhibits signs of previous mining activity

Enumerated_Domain_Value_Definition_Source: USGS Artisanal Diamonds Project

Attribute:

Attribute_Label: Obs_Yr
Attribute_Definition:

Year of satellite image acquisition, from which ASM activity was interpreted.

Attribute_Definition_Source: USGS Artisanal Diamonds Project
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 2013
Range_Domain_Maximum: 2016
Attribute_Units_of_Measure: year

Attribute:

Attribute_Label: Num_Obs
Attribute_Definition:

Number of ASM activity observations (each indicating an individual ASM pit or mine site) within the 1 square kilometer area indicated by each record, for all the years of observation

Attribute_Definition_Source: USGS Artisanal Diamonds Project
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 1
Range_Domain_Maximum: 54
Attribute_Units_of_Measure: observation

Attribute:

Attribute_Label: Latitude
Attribute_Definition:

Y coordinate, in decimal degrees of WGS 84, for the point record's location

Attribute_Definition_Source: WGS 84
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 3.117499
Range_Domain_Maximum: 8.785728
Attribute_Units_of_Measure: decimal degrees

Attribute:

Attribute_Label: Longitude
Attribute_Definition:

X coordinate, in decimal degrees of WGS 84, for the point record's location

Attribute_Definition_Source: WGS 84
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 15.20009
Range_Domain_Maximum: 23.42385
Attribute_Units_of_Measure: decimal degrees

Attribute:

Attribute_Label: N_UTM34N
Attribute_Definition:

Northing coordinate for the point record's location, in meters, UTM 34 N WGS 84

Attribute_Definition_Source: UTM 34N WGS 84
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: 345934.3
Range_Domain_Maximum: 971934.3
Attribute_Units_of_Measure: meters

Attribute:

Attribute_Label: E_UTM34N
Attribute_Definition:

Easting coordinate for the point record's location, in meters, UTM 34 N WGS 84

Attribute_Definition_Source: UTM 34N WGS 84
Attribute_Domain_Values:

Range_Domain:

Range_Domain_Minimum: -144751.6
Range_Domain_Maximum: 767248.4
Attribute_Units_of_Measure: meters

The Central African Republic Diamond Database (2018) - Recent (2013-2017) Mining Activity Dataset

Metadata: