Directorate:  Geohydrology

DATA QUALITY AUDIT PROJECT

The aim of the project is to evaluate the quality of some of the main attributes of borehole records stored in the NGDB, and to improve it as far as possible. The target is to enhance the reliability of the stored data, in relation to captured data, to the level of 95 %.

The following boreholes attributes are being audited:

• site ID, coordinates, accuracy of coordinates, map number, farm name, district number, drainage region code, comment field (all from Entry table)
• depth of borehole (from Hole table) and
• water level, borehole yield (from Aquifer table).

Additionally the borehole records are being linked to groundwater chemical analyses stored in QUALDB, where available. A Data Quality Index is also being prepared for each borehole record (will be described and made available at a later stage).

The data quality audit itself is being undertaken in the PC environment and the audited data is returned back to NGDB. To enhance the quality and efficacy of the undertaking use is being made of:

• ArcView-based procedures to determine basic statistical characteristics of the data sets, and, to visualize borehole locations and
• purpose-tailored program checking the data integrity, and, transmission of audited data sets to the NGDB.

As the project proceeds audited data sets will become available for download in the form of plain text files for each printed 1 : 500 000 scale hydrogeological map sheet. Included in the download files will be the coordinates, Site ID and Data Quality Index of each borehole. The detailed data will be obtainable from the Directorate: Geohydrology on request (possibly based on list of site IDs provided by the user).

Please direct your further questions to Jan Girman.