Monitoring geomorphic and hydrologic change at mine sites using satellite imagery: The Geita Gold Mine in Tanzania

Abstract Large surface mining operations typically involve not only multiple pits but also the creation of new “mountains” of tailings. These operations dramatically change the local watershed topography and expose downslope agricultural fields and forest to tailings runoff. Given that most mine tailings expose large quantities of surface area to oxidation and transport by water, any heavy metals associated with the deposit are mobilized to move along with the runoff. In Tanzania, the Geita Gold Mine (GGM) area is such a site and the Government of Tanzania has yet to develop a water monitoring network to protect villages adjacent to the mines. As a result, mining company data are the only data available to monitor water supply and quality. Typically in mining and oil sand extraction, geospatial data are used to report and monitor land reclamation at the mining site, and while these efforts are useful, they do not consider hydrologic changes and risks. In this paper we evaluate the use of Digital Elevation Model (DEM) data from the Space shuttle Radar Topography Mission (SRTM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) in an effort to identify the changes in local topography and surface hydrology around the GGM and assess the implications these changes have for the potential increased mobility of tailings and their effects upon farmers, village water supplies, and community forests using a hydrologic flow model. Results reveal that over 13 million m 3 of material has been removed from the main mining pits at GGM while over 81 million m 3 of material has been deposited elsewhere in tailings piles and waste dumps. These topographical changes have had a profound influence on the local surface hydrology, with some stream channels shifting up to 3 km from their original paths. Overall, approximately 37 km 2 of cultivated land is within the watersheds associated with potentially polluted streams and that future mining operations could impact up to 63 km 2 of cultivated land.

[1]  Youshouzhai Gu.  Echo , 1980, The Craft of Poetry.

[2]  B. Lees,et al.  Polarimetric Classification in a Tailings Deposition Area at the Timika Mine Site, Indonesia , 2006, Mine Water and the Environment.

[3]  Olga Rigina,et al.  Environmental Impact Assessment of the Mining and Concentration Activities in the Kola Peninsula, Russia by Multidate Remote Sensing , 2002, Environmental monitoring and assessment.

[4]  J. Skousen,et al.  Bulk Density of Rocky Mine Soils in Forestry Reclamation , 2012 .

[5]  Jeffrey A. Cardille,et al.  Strategies for Incorporating High-Resolution Google Earth Databases to Guide and Validate Classifications: Understanding Deforestation in Borneo , 2011, Remote. Sens..

[6]  E. Slonecker,et al.  Remote sensing and mountaintop mining , 2001 .

[7]  Glenn Banks,et al.  Monitoring the Environmental Impact of Mining in Remote Locations through Remotely Sensed Data , 2006 .

[8]  L. Horowitz.  “Twenty years is yesterday”: Science, multinational mining, and the political ecology of trust in New Caledonia , 2010 .

[9]  Nuray Demirel,et al.  Landuse change detection in a surface coal mine area using multi-temporal high-resolution satellite images , 2011 .

[10]  J. Emel,et al.  Calling for Justice in the Goldfields of Tanzania , 2012 .

[11]  John Rogan,et al.  Geomorphic Change Analysis Using ASTER and SRTM Digital Elevation Models in Central Massachusetts, USA , 2010 .

[12]  J. Emel,et al.  Problems with Reporting and Evaluating Mining Industry Community Development Projects: A Case Study from Tanzania , 2012 .

[13]  Peter G. Chirico,et al.  Accuracy Evaluation of an ASTER-Derived Global Digital Elevation Model (GDEM) Version 1 and Version 2 for Two Sites in Western Africa , 2012 .

[14]  Agnes G. Mwakaje,et al.  Environmental Degradation under Artisanal and Small-Scale Mining in Tanzania: Can Innovations in Institutional Framework Help? , 2012 .

[15]  D. Butler,et al.  Mining and environmental change in Sierra Leone, West Africa: a remote sensing and hydrogeomorphological study , 2008, Environmental monitoring and assessment.

[16]  Wayne B. Gray,et al.  The Effectiveness of Environmental Monitoring and Enforcement: A Review of the Empirical Evidence , 2011, Review of Environmental Economics and Policy.

[17]  Andrew Jarvis,et al.  Hole-filled SRTM for the globe Version 4 , 2008 .

[18]  T. Thangaradjou,et al.  Geochemical and geo-statistical assessment of heavy metal concentration in the sediments of different coastal ecosystems of Andaman Islands, India , 2010 .

[19]  Leticia Carrizales,et al.  Arsenic and Heavy Metal Pollution of Soil, Water and Sediments in a Semi-Arid Climate Mining Area in Mexico , 2004 .