How a dry year affects spatial variability of ground thaw and changes the hydrology of a small Arctic watershed

• Main Author: Dakin, Brampton
• Format: Master Thesis
• Language: English
• Published: University of Waterloo 2023
• Subjects: numerical modelling; permafrost science; cold regions processes; Arctic; Climate change; Inuvik; permafrost
• Online Access: http://hdl.handle.net/10012/19976

The summer of 2021 in the Inuvik area, NWT was warm and dry. As recorded in Siksik Creek, a sub-catchment of Trail Valley Creek located 50 km north-east of Inuvik, this was the 7th warmest summer and driest July recorded to date. This presented a unique opportunity to study the drying phenomena of Arctic ecosystems. This is pertinent to the study of permafrost degradation, as the drying phenomena is still vastly understudied and there are few datasets available that record abnormally dry conditions in Arctic catchments. These data sets are needed to properly show the influence that this has on active layer thicknesses. It is unknown whether these conditions may pose a risk to permafrost, if this is spatially variable, and what other processes might amplify or hinder this. The main objective of this thesis is to explore how a dry year affects active layer thaw and the hydrology of Siksik Creek so that we may better understand how catchments such as Siksik will respond to ongoing climate change. To do this a mix of field results and modelling was used to show and quantify how these may affect active layer thaw as well as water balance components. The three main research chapters of this thesis divide this by analyzing active layer thaw as physically measured in the catchment to previous years, by using the model GEOtop to assess how this affects water balance components, and then by simulating wetter conditions to show the affect soil moisture has. Field data were collected from May 25th to August 29th in Siksik Creek during the summer of 2021, where the data collected included active layer thicknesses, depth to the water table, as well as stratigraphy and soil thicknesses across a variety of terrain type throughout the entirety of the catchment. This study specifically focused on measuring these data across hummocks and inter-hummocks throughout the catchment, as these features are ubiquitous in the Mackenzie uplands. In addition to analyzing the 2021 field data, the GEOtop physically based hydrology model was ...