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

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Frequently anticipated questions:

What does this data set describe?

Title:
The Central African Republic Diamond Database (2018) - Recent (2013-2017) Mining Activity Dataset
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).
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
  1. How might this data set be cited?
    Chirico, Peter G., DeWitt, Jessica D., Bergstresser, Sarah E., and Clark, Inga E., 2018, The Central African Republic Diamond Database (2018) - Recent (2013-2017) Mining Activity Dataset: U.S. Geological Survey, Reston, VA.

    Online Links:

    This is part of the following larger work.

    DeWitt, Jessica D., Chirico, Peter G., Bergstresser, Sarah E., and Clark, Inga E., 2018, The Central African Republic Diamond Database – A Geodatabase of Archival Diamond Occurrences and Areas of Recent Artisanal and Small-scale Diamond Mining: U.S. Geological Survey, Reston, VA.

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 14.414062495844
    East_Bounding_Coordinate: 27.421874995324
    North_Bounding_Coordinate: 11.070173525592
    South_Bounding_Coordinate: 2.3499775496997
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2013
    Ending_Date: 2017
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: GIS data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set.
    2. What coordinate system is used to represent geographic features?
      The map projection used is Transverse Mercator.
      Projection parameters:
      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 coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 10.0
      Ordinates (y-coordinates) are specified to the nearest 10.0
      Planar coordinates are specified in METERS
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    Recent_mining_1km2_areas_2013_2016
    locations of ASM activity interpreted from high resolution satellite imagery (Source: USGS Artisanal Diamonds Project)
    OBJECTID
    Unique identification number for each point record (Source: Automatically populated by ESRI ArcGIS 10.4)
    Range of values
    Minimum:1
    Maximum:1815
    Shape
    Geometry of the GIS data record (Source: ESRI ArcGIS 10.4) All records in this dataset are 'point' shapes.
    ASM_Val
    Type of artisanal and small-scale mining (ASM) activity observed in satellite imagery at a mine site. (Source: USGS Artisanal Diamonds Project)
    ValueDefinition
    1Site has mining activity (generic)
    2Primarily excavation activity (signs of active digging, including benching, angular pit sides, and spoil piles)
    3Washing of gravel material in pits or other nearby water body
    5Site is currently inactive based on image indicators (see DeWitt and others, 2017), but exhibits signs of previous mining activity
    Obs_Yr
    Year of satellite image acquisition, from which ASM activity was interpreted. (Source: USGS Artisanal Diamonds Project)
    Range of values
    Minimum:2013
    Maximum:2016
    Units:year
    Num_Obs
    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 (Source: USGS Artisanal Diamonds Project)
    Range of values
    Minimum:1
    Maximum:54
    Units:observation
    Latitude
    Y coordinate, in decimal degrees of WGS 84, for the point record's location (Source: WGS 84)
    Range of values
    Minimum:3.117499
    Maximum:8.785728
    Units:decimal degrees
    Longitude
    X coordinate, in decimal degrees of WGS 84, for the point record's location (Source: WGS 84)
    Range of values
    Minimum:15.20009
    Maximum:23.42385
    Units:decimal degrees
    N_UTM34N
    Northing coordinate for the point record's location, in meters, UTM 34 N WGS 84 (Source: UTM 34N WGS 84)
    Range of values
    Minimum:345934.3
    Maximum:971934.3
    Units:meters
    E_UTM34N
    Easting coordinate for the point record's location, in meters, UTM 34 N WGS 84 (Source: UTM 34N WGS 84)
    Range of values
    Minimum:-144751.6
    Maximum:767248.4
    Units:meters

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
    U.S. Department of State, U.S. Agency for International Development
  3. To whom should users address questions about the data?
    Peter G. Chirico
    U.S. Geological Survey
    12201 Sunrise Valley Dr.
    Reston, VA
    USA

    703-648-6950 (voice)
    pchirico@usgs.gov

Why was the data set created?

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.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2016 (process 1 of 1)
    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.
  3. What similar or related data should the user be aware of?
    DeWitt, Jessica D., Chirico, Peter G., Bergstresser, Sarah E., and Clark, Inga E., 2018, The Central African Republic Diamond Database – A Geodatabase of Archival Diamond Occurrences and Areas of Recent Artisanal and Small-scale Diamond Mining: U.S. Geological Survey, Reston, VA.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    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).
  2. How accurate are the geographic locations?
    No formal positional accuracy tests were conducted
  3. How accurate are the heights or depths?
    No formal positional accuracy tests were conducted
  4. Where are the gaps in the data? What is missing?
    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.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted

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:
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.
  1. Who distributes the data set? (Distributor 1 of 1)
    Peter G. Chirico
    U.S. Geological Survey
    12201 Sunrise Valley Dr.
    Reston, VA
    USA

    703-648-6950 (voice)
    pchirico@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Public domain data from the U.S. Government are freely distributable 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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    This dataset is formatted as a feature class in an ESRI geodatabase. It requires the user to have geospatial software such as ESRI ArcGIS, Blue Marble Global Mapper, Que GIS, GRASS, or other GIS software.

Who wrote the metadata?

Dates:
Last modified: 05-Apr-2018
Metadata author:
Peter G. Chirico
U.S. Geological Survey
12201 Sunrise Valley Dr.
Reston, VA
USA

703-648-6950 (voice)
pchirico@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Generated by mp version 2.9.47 on Thu Apr 5 06:49:02 2018