Multi-method evaluation of groundwater-surface water interactions and chloride transport in an urban tributary in southern Ontario, Canada
Bibliographic record
Abstract
Interactions between groundwater and surface water (GW-SW) strongly influence streamflow dynamics and solute transport, especially in urban catchments where discharging groundwater can be a notable source of contaminants, such as chloride (Cl - ). Across the Great Lakes Basin, extensive road salt use has led to chronically high Cl - concentrations in groundwater, raising concerns about its long-term contribution to surface water salinization. Understanding the spatiotemporal dynamics of GW-SW exchange is essential for evaluating Cl - transport and its impacts on urban water quality. This study examines GW-SW interactions and Cl - dynamics in an urban stream in southern Ontario, Canada, over a 2-year field campaign (May 2022 – April 2024), aiming to characterize exchange variability, assess groundwater’s role in shaping in-stream Cl - concentrations, and evaluate local hydrogeologic controls. A multi-method approach was used, including streambed temperature mapping and vertical profiles, seepage meters, hydraulic gradient measurements, and geochemical sampling (δ 18 O, δ 2 H, and Cl - ) to assess exchange dynamics and relative groundwater contributions. Results revealed spatial variability in groundwater discharge, with persistent upward flow confirmed by temperature-based methods and Darcy’s Law. Concentrations of Cl - in groundwater consistently exceeded aquatic life guidelines (120–––640 mg/L), particularly in the streambed drive-points, indicating persistent Cl - loading to surface water, even outside of winter months. These findings highlight the importance of groundwater as a long-term Cl - source in urban streams and demonstrate the value of an integrated approach for evaluating GW-SW interactions in cold-region watersheds.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| 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 teacher head, 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".