MONITORING ECOSYSTEMS WITH SATELLITES
THE CHURCHILL-NELSON RIVERS DIVERSION IN MANITOBA
In September of 1969 I was doing fieldwork in Northern Manitoba as part of the Canada Land Inventory Project and the in preparation of the Manitoba Remote Sensing Test Projects. Our fieldwork was concentrated in the Wekusko (63J), Grand Rapids(63G), Norway House (63H) and Cross Lake (63I) topographic map sheet areas.
During the fieldwork using helicopters, fixed wing aircraft, and boats we collected a wide range of vegetation, soil, and photographic data which I am reviewing now, almost 50 years later to study environmental change especially the melting of permafrost in palsas and peat plateaus so common in these area. Much of this data and imagery allows us to visualize not only the impacts of climate change on permafrost but also to visualize the impact of the major Churchill- Nelson Rivers Diversion on the environment like the impact of flooding.
An good example of this source of aerial photos is the following image taken from a helicopter in the fall of 1969: The amount of tree kill is very high because wetlands with permafrost were flooded. The original floating peat wetlands adjusted to the new water level (green arrow right)l, but the mainly Black Spruce forest on peat plateaus were flooded and killed (red arrow). It is interesting to see that the former collapse scars of the peat plateaus also float and adjusted to the new water level (green arrow left).
Unfortunately, the Google Earth below does not provide high resolution images for this area. The two slide sites are marked on the GE image below, taken in 1982 and showing a messy situation after the part of tree kill was removed.
The Apple Maps program provides very high resolution images for part of this area. In spite of the clouds the image shows that the floating wetlands are still floating. Dead trees have been removed along the shoreline. The logging road is visible on both the Google Earth and Apple Maps image. It did not exist at the time of the helicopter photo. Both satellite images show the very merky colour of the lake water. Much of the original shoreline was composed of lacustrine clay and silt deposits from Glacial Lake Agassiz. Since the flooding the erosion of this silt and clay have changed the lake.
Also the slide below provides a good visualization of the extent of the flooding damage. The the tree kill along the shorelines is quite obvious. Also the tree kill in wetland is extensive(light blue arrow)
The earlier slides clearly show the extent of damage. It is less clear in the slide below. The water table here is visibly higher than the natural fluctuation, resulting in more tree kill than would be normal under the natural degradation cycle of the peat plateau permafrost.
The Manitoba Wildlands organization provided the map below showing, among others, the Churchill-Nesson Diversion area.