Controls on DOC Flux in Continuous Permafrost Watersheds

• Main Author: Momejian, Nanor
• Other Authors: Geography and Planning, Lafreniere, Melissa, Mabee, Warren
• Format: Thesis
• Language: English
• Published: 2022
• Subjects: Dissolves Organic Carbon; Permafrost; Transport-Limited; Soil and Water Assessment Tool (SWAT); Canadian High Arctic; Soil organic carbon; Arctic; permafrost
• Online Access: http://hdl.handle.net/1974/30183

The overarching purpose of this study is to develop a framework to model dissolved organic carbon (DOC) flux using only surface runoff and/or remotely acquired biophysical (terrain, vegetation, soil) data in environments that are remote and/or have limited data. To achieve this, this study focuses on (1) establishing a correlation between daily DOC flux and daily surface discharge, (2) finding a relationship between soil physical characteristics and soil organic carbon-SOC (source of DOC carbon), and (3) assessing the accuracy of a modelling tool in hydrologic modelling of watersheds on continuous permafrost in the High Arctic. The results of this work demonstrate that there is a significant positive correlation between surface runoff and DOC flux, except in the cases of surface physical disturbance which can increase both discharge and DOC flux. The work also determines that High Arctic watersheds, similar to other watersheds in North America, are transport limited (DOC controlled by discharge) for all the runoff components (nival, base and stormflow). The analyses found a statistically significant correlation between soil moisture and SOC, demonstrating that remotely acquired soil moisture data could help map SOC in watersheds on continuous permafrost in the High Arctic, which could improve carbon stocks estimates in the region. The significance of spatial variability of SOC builds on the importance of using a spatial hydrological modelling tool in High Arctic watersheds. SWAT was chosen as an appropriate tool; assessment of this tool showed that snow-related parameters, particularly snowmelt temperature, greatly influences the modelled discharge, while the soil parameters have little to no impact on the modelling output. Overall, the study found that the highest contributor to the total discharge is snowmelt, except when rainfall events are very high, and stormflow becomes the largest contributor to discharge. The increase in rainfall dominance is part of the climatic predictions of the Arctic, therefore, a ...