Permafrost thaw induced changes to runoff generation and hydrologic connectivity in low-relief, discontinuous permafrost terrains
Recent climate warming in northwestern Canada is occurring at an unprecedented rate in recorded history and has resulted in the widespread thaw of permafrost. Where present, permafrost exerts a significant control on local hydrology, and disappearance of permafrost threatens to change the hydrology...
| Main Author: | |
|---|---|
| Format: | Text |
| Language: | English |
| Published: |
Scholars Commons @ Laurier
2017
|
| Subjects: | |
| Online Access: | https://scholars.wlu.ca/etd/1976 https://scholars.wlu.ca/context/etd/article/3089/viewcontent/Connon_Thesis.pdf |
| Summary: | Recent climate warming in northwestern Canada is occurring at an unprecedented rate in recorded history and has resulted in the widespread thaw of permafrost. Where present, permafrost exerts a significant control on local hydrology, and disappearance of permafrost threatens to change the hydrology of northern basins. In the peatlands that characterise the southern distribution of permafrost in low relief terrain, permafrost takes the form of forested peat plateaus and is interspersed by permafrost-free wetlands (i.e. channel fens and flat bogs). Previous field studies have found that channel fens serve as the drainage network and route water to the basin outlet, whereas flat bogs have been viewed primarily as storage features. Wetland expansion in response to permafrost thaw can transform the primary hydrologic function of flat bogs from storage units to runoff-producing units by removing the relatively impermeable permafrost barrier that encompasses them. As a result, permafrost thaw has the potential to greatly increase the runoff contributing area when large storage features form hydrological connections with the basin drainage network. It has been well documented that permafrost thaw in this region results in the loss of forest and a concomitant expansion of wetlands, however the hydrologic response of these changes is poorly understood. Stream flow records in four Water Survey of Canada gauged basins (152 - 2050 km2)in the lower Liard River valley were analyzed to determine the impact of permafrost thaw-induced land cover change on basin runoff. Annual runoff between 1996 and 2012 increased by between 112 mm and 160 mm and these changes were significant in all four basins (p>0.05). Changes to stream flow were assessed using the Mann-Kendall non-parametric test and the Kendall-Theil robust line. Permafrost thaw between 1977 and 2010 was quantified by comparison of historical aerial photographs and high-resolution satellite imagery (World View 2) over a 6 km2 area of interest, where changes in ... |
|---|