The rich biological diversity of the Mackenzie Delta region, with large populations of fish, fur-bearing mammals, caribou and waterfowl, is because of the complex interactions among the region's various components. In order to predict the effects of change, it's important to better understand how the components of an integrated system interact.
One example of such interaction is the fresh water fish migration between the lakes of the Tuktoyaktuk Peninsula and the Mackenzie Delta. The health of this population is partially controlled by the hydrological conditions in these two apparently unrelated portions of the delta region, as well as the conditions controlling the low-salinity freshwater plume required for migration through the coastal sections of the Beaufort Sea.
As with many northern ecosystems with interconnected lakes and rivers, the Delta region is expected to be sensitive to climate change and variability: in fact, the entire Mackenzie Basin has experienced significant warming over the last 30 years. In this context, ongoing studies at Environment Canada are aimed at improving the understanding of the Delta system and the natural variability in its climate/hydrology during the last 30 years, and at developing possible techniques for predicting future changes.
One study has considered the effect of climate on the levels of lakes in the Delta. A lake hydrology model was used to predict lake levels under the present climate and one in which atmospheric carbon dioxide is doubled. The model showed that for periods when the highest-elevation lakes (one-third of all delta lakes) were not flooded by the Mackenzie River, water levels declined significantly faster under the hypothetical future climate conditions compared to present ones, with the lakes eventually disappearing in 10 years.
The Mackenzie Delta, the largest in Canada, is located where the largest Canadian river, the Mackenzie, enters the Beaufort Sea. Critical components of the Delta region include: the Delta itself, the Beaufort Sea, the surrounding uplands, the Tuktoyaktuk Peninsula, the Eskimo Lakes estuary, and the Mackenzie/Peel rivers.
During the last 30 years, flooding by the Mackenzie River has occurred frequently enough to refill lake basins before they dry up. Even though break-up flooding has been occurring increasingly earlier in the spring, there has been no apparent change in the frequency of flooding. The ability to predict future changes in flooding is very limited; however, it is being partially addressed by a joint university/Environment Canada project studying the hydrology and climate of the Mackenzie Basin. This study will lead to an improved ability to predict discharge from the Mackenzie Basin into the Delta. Further work will then be needed to use this information to predict ice break-up in the Delta, and therefore the flooding of delta lakes.
Another study is examining how the hydrology of the uplands surrounding the Mackenzie Delta may react to a changing climate. The area is characterized by continuous permafrost, with the upper few metres being very ice-rich. Melting of this permafrost will result in extensive ground slumping and will modify the processes of catastrophic lake drainage or enlargement. Determining the rates of these changes, the impact on lake hydrology and the subsequent effect on fish and waterfowl species are study objectives that will be pursued by Environment Canada scientists using modelling techniques.