Over the past ten years, significant changes in legislation surrounding mine closure have occurred at both the provincial and federal levels. The emphasis on long-term responsibility for the environmental impacts of mining requires that cost-effective tools for monitoring are available to industry and regulators. The SDKI Sustainable Management and Rehabilitation of Mine Sites for Decision Support project is working collaboratively with federal departments, provincial governments and industry to develop and improve existing tools for site monitoring.

An example of these tools in action is given in Figure 1. Maps were extracted from high-spectral resolution earth-observation data, collected over the Copper Cliff tailings impoundment. Images from an airborne sensor were collected in the summers of 1996, 1998 and 1999 to illustrate progress in revegetation over tailings areas at the site.

Figure 1. Changes in vegetation cover during a three-year period over a section of the Copper Cliff tailings impoundment. Maps were derived from airborne hyperspectral images collected in the summers of 1996, 1998 and 1999.

A re-vegetation program was initiated at the site to control dust emissions from the tailings areas. This included a program of progressive reclamation, that included liming, fertilizing and seeding older tailings areas with a combination of grasses. The progress of these measures can be seen in the increase in vegetation over the three-year period.

Figure 2. A map of the KamKotia mine near Timmins, Ontario, made by layering three years of RADARSAT data (1992, 1996 and 2002). Areas with a red-tone indicate where the greatest change has occurred in the three-year period.

Figure 2 shows a false-colour image using RADARSAT satellite images acquired in 1992, 1996 and 2002 over the Kamkotia abandoned mine near Timmins, Ontario. Areas appearing red in colour are where the greatest changes have occurred over the ten-year period. Satellite data from radar sensors detect backscatter information from ground targets, and are ideal to distinguish variability in surface "roughness" (i.e the transition from a smooth surface to a vegetated one) or moisture content. In this simple colour composite, areas within the tailings boundaries show greater change than the areas outside these boundaries, in particular the area of the North Unimpounded Tailings, where rehabilitation work began in 2002. Changes in the other tailings areas could represent subtle changes in moisture content, possibly as a result of hydrological changes that occurred at the site when a water treatment plant was constructed in 2001.

Using advanced data integration techniques developed through SDKI, spatial data from a variety of sensors and sources can be used to exploit differences in the information they depict. These can be used synergistically with other geospatial data as part of a long-term monitoring plan.