Comparison of permafrost thaw-related changes to hydrological response and land cover in subarctic peatland-dominated landscapes

• Main Author: Mack, Mikhail
• Format: Text
• Language: English
• Published: Scholars Commons @ Laurier 2023
• Subjects: permafrost thaw; peatland-dominated landscapes; hydrological response; runoff ratio; peatland complex; permafrost peatlands; circuitry analog; tasseled cap; Fresh Water Studies; Hydrology; Canada; Hudson; Kendall; permafrost; Subarctic; taiga; Taiga plains
• Online Access: https://scholars.wlu.ca/etd/2531; https://scholars.wlu.ca/cgi/viewcontent.cgi?article=3680&context=etd

The hydrological implications of discontinuous permafrost thaw in peatland-dominated basins are not well understood. While there is evidence suggesting that permafrost-thaw-driven land cover change increases annual runoff and the runoff ratio in the Taiga Plains of northwestern Canada, few studies have evaluated the impact on small to medium-sized basins (< 105 km2) outside this ecoregion. Here, we assess runoff, runoff ratio, and precipitation trends for 34 peatland-dominated basins, of which 28 are in the discontinuous and sporadic permafrost zones and 6 in adjacent permafrost-free environments. We calculated annual and monthly trends between 1970 and 2016 using the Mann-Kendall test and found that annual runoff, runoff ratio, and precipitation increased significantly in 25%, 16%, and 13% of basins respectively, at a 5% significance level, and decreased significantly in 3%, 19%, and 9% of basins, respectively. Increased annual runoff ratios occurred exclusively in basins overlying permafrost, while increases and decreases in annual runoff and precipitation were found in both permafrost and permafrost-free basins. Increases in annual runoff and runoff ratio occurred independently of precipitation changes in only the Taiga Plains and the Western Siberian Plain. Runoff during winter increased significantly in all ecoregions and occurred independently of the areal extent of permafrost, although the magnitude of these increases was small compared with those of April and May. The Hudson Plains, Canada is one of the largest, undisturbed peatland regions (370,000 km2) in the world. Air temperature in the Hudson Plains is increasing rapidly leading to unprecedented permafrost thaw. The region’s remoteness has hindered our knowledge of how permafrost thaw alters peatland land cover and hydrological response. However, such relationships have been intensively studied in the Taiga Plains of northwestern Canada and have demonstrated that the thaw and subsidence of permafrost peatlands in sporadic (30% – 80% areal) ...