Since the discovery of gold in the Witwatersrand in 1886, several mines have been developed and hundreds of shafts have been dug in this region. Some were immediately abandoned when insufficient minerals were found, others were abandoned later when poor economics of the gold commodity made mining unprofitable, and others are still being exploited. The result is that the Gauteng’s landscape is characterised by the presence of active and abandoned mines, their residues and underground voids, many of which pose health, safety and environmental hazards.
Quite uniquely, compared to other areas of the world, the problems and hazards posed in particular by the mines occur in a major metropolitan area. Mitigations and reclamation projects of mine residue areas and abandoned mines have started and classifications of various hazards to the ecosystem and people are underway. Several reports (Gauteng Department of Agriculture and Rural Development, (2012) and Department of Mineral Resources, (2009)) have been published on this topic and some research is available for public consultation. These remain, nevertheless, fragmented attempts, whereas the magnitude and scope of the problem of abandoned and active mines can only be fully comprehended through the acquisition, mapping and combined analysis of all signatures that mining has left in this urbanised landscape. At present, information on the location of mines, mining related landscape units and their characteristics, in particular in digital format, is limited and not easily accessible.
Fig. 1: Outlines of mine reefs and shafts were digitised from the historical maps to create historical vector data.
A project was initiated to create a database containing historical data on mining and related activities which would also serve as a platform for collating all other research outputs. This was done as part of the Wits Digital Mine Project in the School of Mining Engineering at the University of the Witwatersrand. It is a multidisciplinary initiative aimed at the integrated use of different technologies from a wide sphere of scientific fields to improve subsurface communication systems and mine working conditions. Convenient and snowball sampling methods were used to identify concerned organisations or institutions with relevant research and environmental projects, while simultaneously conducting a web and manual search for suitable spatial data or any recordings on operational and discontinued mining operations.
The quality of spatial data on ongoing mining activities was checked according to ISO 19100 guidelines. Historical paper maps were digitised using laws of photogrammetry, which entailed the stitching together of historical maps, data transformation from the Gold Fields coordinate system to the South African datum and manually digitising features of interest on the maps (see Fig. 1). All data retrieved from the user requirements assessment was categorised to make the evaluation easier and later used to inform the database design process.
Fig. 2: GeoServer web-interface architecture. GeoServer is an open source online server. It is a full transactional Java implementation for web feature and coverage service with an integrated web map service (WMS) as specified by the Open Geospatial Consortium.
The outcome of this research has been a spatial database containing historical and contemporary data on mining and related activities created using PostgreSQL and mounted on an online platform called GeoServer (see Fig. 2); both of which are open source software. The database contents can be visualised through the use of select statements on PostgreSQL or alternatively through the establishment of a connection with QGIS and other GIS software or through the use of the GeoServer GUI and published using GeoExplorer (see Fig. 3). Provisions have been made for research outputs from other members of the Wits Digital Mine Project, which will be included as they become available.
The database is expected to be of use to at least all members of the Wits Digital Mine Project, students of the University of the Witwatersrand and stakeholders involved in the project. The database can be used for baseline studies, to support research, environmental management, mine safety, urban and rural planning and also as a basis for the framework used to analyse, remedy as well as predict future challenges in the mining industry. Moreover, should the database be made accessible to the general public it would play an important role in that it would make interested parties more aware of what data exists and where it can be acquired, and it could therefore be used to inform decision-making at all levels.
Fig. 3: When the map composed on GeoExplorer is published and embedded onto a webpage, the webpage can be viewed by all individuals with GeoServer on their computers.
An evaluation of the data collected for the purpose of the study shows that a wealth of information exists on discontinued and ongoing mining related activities, however the latter is more available than the historical data. The limitations in data accessibility appear to be somewhat of a systematic problem influenced by a number of factors such as copyright restrictions, associated data costs, availability of data in proprietary formats, discrepancies in the data request process, and fragmented and overlapping mandates.
Furthermore, there is a lot of redundancy in the data that is available. Consequently, data that is available is in need of further verification. The work reported in this article is part of an MSc research study in the School of Geography, Archaeology and Environmental Studies at the University of the Witwatersrand.
Contact Ntandoh Khanyile, University of the Witwatersrand, ntandoh.khanyile@gmail.com
