The mining of iron ore is not the only source of big holes in the continent. Excavations on a huge scale also characterise open cut coal mines. Coal is now a significant component of Australia's export earnings: 12% or $6.4 billion in 1990-1991, more than the total for all agricultural products. There has been a significant growth in this mining landuse in the last two decades, the time over which we are able to look back with satellite images.
The most extensive development of surface mining of coal has been in Central Queensland. Here this landuse has been interspersed with the existing landuses of Pastoralism and Agriculture. This region is therefore an interesting place to look back because we can compare the influences of all three landuses.
Use your browser to open each image in a new window to compare them.
Landcover change in the Clermont area of Central Queensland during the period 28/08/72 to 01/08/91. The best way to interpret these three images is to begin with the later one. The surface coal mining activity can be interpreted as the long broken strip of blue running diagonally across the image. This signature is of the very large heaps of stockpiled surface material (overburden). Most of the mines were not present in the early image.The Difference FCC image says it all. I estimate that approximately 15% of the scene has lost landcover (dark tones). Most of that is in the upper RHS of the image. By eyeballing the early and late images, you can interpret these landcover changes as resulting from clearing of woodland. Some of this clearing has been on land of substantial slope.
From the ground and from a distance, the volumes of material shifted during the surface mining of coal appear to create new landscapes. As I was collecting ground photography to illustrate this book, I was astonished by the magnitude of the surface workings and the volume of overburden that was shifted before mining could begin. I was equally impressed that, in the final stages of the life of the mine, these large amounts of material were to be shifted back again and the surface rehabilitated as far as possible before abandonment.
In contrast to the impressions gained by a surface visit, the view from space pronounces the aggregate area of all this activity, so impressive on the human scale, relatively insignificant. It is the landuse of Pastoralism that has transformed the landcover of this part of Central Queensland, not Mining. The landcover changes related to mining are distinct, but relatively minor in overall area.
