Melting of Peat plateaus in the Limestone Bay Area, Manitoba





Monitoring of Landslides in Permafrost
















Summary: High Resolution Google Earth images (2004-6) are compared with 1972-3 high resolution airborne colour and colour infrared images to assess melting of permafrost in peat lands.

In the 1971-73 period we carried our field work in Northern Manitoba to provide baseline information for a Northern Biophysical Survey of Manitoba and to Evaluate Remote Sensing Techniques for Biophysical Land Classification (Thie, 1976). The teams included Charles Tarnocai, Bob Smith, Gordon Mills, Dr.Gerry Beke and Jean Thie during the various field seasons. The Canada Centre for Remote Sensing, carried out airborne multi-spectral and thermal scanning missions as part of the multi-disciplinary and multi-stakehoder Manitoba Remote Sensing Program.

The area was flown during the summers of 1972 and 1973 with a Falcon Fan Jet at 10,000 meters above seal level (ASL) and selected areas at 1525 and 3050 M. ASL.

Figure 1:

A typical example of the type of permafrost landforms in wetlands is provided by the slide below taken from a beaver aircraft using a telephoto lens in 1972. Area A shows a collapse scar where permafrost has melted. The small black spruce trees are slowly being submersed in the waterlogged scar. The area around B is typical of the non-frozen wetland. Sparse growth of Tamarack (Larix Laricina) can be seen here in a poorly developed ribbed fen. drainage is from right to left. Around D is a typical growth of stunted Black Spruce (Picea Mariana) can be seen. Light coloured ground cover between the spruce is a combination of lichen and mosses.

Figure 2:

The same area is show in a high resolution Google Earth image 'taken' at about 140 meters above ground level. Date of image 2003- Aug 27.

There is a significant 31 year time difference between the two images but initially no significant differences are apparent. It is interesting to look at these two images combined on Google Earth: try this KMZ link


The 1973 summer and winter Landsat images give a good perspective of the lack of tree cover in this area. The winter image on the right enhances the visibility of the very limited and sparse tree cover in this area. The peat plateau of the slide and the GE image is located in the top part of the white circle. The high red on the summer (false colour ) image shows an abundance of stunted tamarack, black spruce, dwarf birch, willow and alder on peat plateaus fens and stream beds. the more yellow tones around A show sparsely covered or bare peat plateaus. Bare peat polygons or polygonal peat plateaus are common around B. D shows some of the former strand lines, again enhanced by larger trees and denser coverage. Around C treed peat plateaus are predominant.