Bibliographic record
Abstract
Hydrology and hydrological modelling in the far north is understudied, and many gaps exist in the current understanding and representation of northern thermal and hydrological systems. A combination of fieldwork and modelling was used to gain a better understanding of landscape evolution and thaw processes in the peatland-dominated discontinuous permafrost region of the Northwest Territories. Data collected at the Scotty Creek Research Station and modelling tools are developed and used to identify and quantify controls on isolated and connected talik formation in discontinuous permafrost peatland systems which include soil moisture, snow cover, surface temperature and subsurface lateral flow. The formation of a talik was shown to be a tipping point in permafrost degradation after which several positive feedback cycles led to more rapid permafrost loss. \n \n \nGiven the widespread prevalence of taliks in this discontinuous permafrost peatlands environment, seasonal pressure and temperature gradients were analyzed in different talik configurations to determine the impacts of taliks on the landscape. It was found that the formation of taliks led to a balance between increased hydrologic storage due to isolated talik prevalence, and increased discharge from the basin due to connected talik features allowing previously inaccessible runoff features to be connected to the drainage network. Thermodynamically speaking, the interplay between subsurface temperature, thaw rates, subsidence, snow accumulation, canopy coverage and soil moisture were discussed supporting the idea that talik formation is a positive feedback for permafrost loss. It is also noted that the loss of permafrost causes subsidence and geophysical destabilization leading to ecosystem change and a change in greenhouse gas emission regimes. \n \n \nExisting models representing permafrost and other cold-regions processes are either computationally expensive physically-based models, or empirically based. This limits their predictive ability at the watershed scale or larger. Large-scale predictions of the impacts of changing climate and subsequent permafrost thaw are needed to improve our understanding of long-term evolution of semi-discontinuous permafrost landscapes. To extend predictions to this scale, a novel physically-based interface model of active layer and permafrost evolution is developed and validated against both field data and a benchmarked continuum numerical model. This simplified model is designed to be incorporated into a semi-distributed hydrological model that will be used to predict hydrologic impacts of changes in permafrost dynamics at the basin scale. This model was used to inform the current understanding of permafrost thaw mechanisms in this environment. \n \n \nIn order to quantify the rate of permafrost loss, different parts of the landscape are classified based on the mechanisms for permafrost thaw including conduction and advection in both the vertical and lateral directions. These results help to explain the observed heterogeneity in thaw rates in the landscape. It was found that conduction is responsible for much of the thaw in the vertical direction, while advective processes do play a role in flow-through talik features. Lateral thaw is occurring more rapidly than vertical thaw, due both to conduction and advective heat transfer. Finally, thaw from below is documented both due to geothermal heat flux, and observed deep thermistor temperature profiles. The combined fieldwork and modelling efforts provide a better understanding of the rapidly changing discontinuous permafrost environment, help to predict hydrologic and landscape changes in Canada's north, and create tools which are transferable to other cold-regions environments.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".