When ice melts and water disappears
Climate change, along with rising air temperatures, has a major impact on the quantity and availability of water in many ways. As a result, there are also ecological impacts on the entire ecosystem. One of the catchments that has been severely affected by climate change and is also currently facing controversy over the use of large amounts of water to extract the lowest quality oil resource (bitumen) is the Athabasca River Basin in Canada. Milada Matoušková and Kateřina Fraindová from the Department of Physical Geography and Geoecology at the Faculty of Science of Charles University focused on the specific impacts in detail.
The Athabasca River is interesting for several reasons. There are many national parks and reserves throughout the catchment, from its headwaters in the Rocky Mountains, where it flows out of Banff National Park, to its mouth at Lake Athabasca in the largest natural protected area in the world, Wood Buffallo National Park. The National Park, along with the Peace River Delta and the Athabasca River, is also a very important corridor for migratory birds, including the critically endangered American Crane (currently a population of only about 400).
On the other hand, unfortunately, the basin is also known for the extraction of tar sands in the north of the basin, which has significant negative ecological impacts - extensive tailing ponds along the river, with leakages of ecotoxic substances into the river (associated with, among other things, fish mutations and increased incidence of human cancer), air pollution, frequent leaks of tar sands from oil pipelines, and the huge amount of water needed to extract the bitumen. Coupled with this are the economic negatives for Canada, as most of the money ends up in foreign countries (not to mention bitumen being one of the least recoverable energy sources). However, the environmental remedies lie with the Canadian government and local citizens.
The results of the study showed that since the early 1960s there has been a significant decrease in discharge in the middle and lower Athabasca River, in some cases up to 25%. These changes have had a negative impact on the natural environment and water resources in the catchment, especially during the winter months. This is generally the time of year when discharge is the lowest, generally below 10 % of annual runoff. Recently, there has been a significant decline in even minimum flows, sometimes causing freezing of stream reaches throughout the profile. This situation significantly affects winter habitat and the ability of fish populations to migrate for food. Socio-economic activities concentrated in this part of the catchment can also be expected to be strongly affected by these changes.
There are several factors influencing the decline in discharge. Spring runoff is reduced mainly due to a decrease in winter snowfall and thus the amount of snowpack that is important part of the spring runoff. As a result of warming, which has been very pronounced in the prairie regions of western Canada over the past century, potential evapotranspiration (the amount of evaporation that would occur if a sufficient water source were available) has also increased. Significant warming has also occurred upstream where glaciers are retreating rapidly. For example, the Athabasca Glacier, which is one of the outlets of the large Columbia Icefield, has already retreated by more than 1.5 km since the early 20th century. If glacier retreat continues, there will be even greater reductions in discharge in the future, as there will be "nothing" to melt. It is also necessary to take into account the overall change in the hydrological regime of the river.
The Athabasca River watershed is currently facing many stressors and pressures - in particular, glacier retreat, loss of snowpack, increased evapotranspiration, and thus a significant decline in river discharges. In order to avoid catastrophic consequences in the catchment, it is now important to select an appropriate strategy for water management and land use in this vulnerable ecosystem.
Kateřina Fraindová
Published:
Jun 26, 2023 08:25 PM
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