Electrical Resistivity Dynamics beneath a Fractured Sedimentary Bedrock Riverbed in Response to Temperature and Groundwater/Surface Water Exchange
Bibliographic record
Abstract
Abstract. Bedrock rivers occur where surface water flows along an exposed rock surface. Fractured sedimentary bedrock can exhibit variable groundwater residence times, anisotropic flow paths, heterogeneity, along with diffusive exchange between fractures and rock matrix. These properties of the rock will affect thermal transients in the riverbed and groundwater–surface water exchange. In this study, surface electrical methods were used as a non-invasive technique to assess the scale and temporal variability of riverbed temperature and groundwater–surface water exchange beneath a sedimentary bedrock riverbed. Conditions were monitored on a semi-daily to semi-weekly interval over a full annual period that included a seasonal freeze-thaw cycle. Surface electromagnetic induction and electrical resistivity imaging methods captured conditions beneath the riverbed along a pool-riffle sequence within the Eramosa River, Guelph, Ontario, Canada. Geophysical datasets were accompanied by continuous measurements of aqueous specific conductance, temperature and river stage. Vertical temperature profiling conducted in an inclined borehole underlying the river revealed active groundwater flow zones through fracture networks within the upper 10 m of rock. Resistivity measurements during cooler high-flow and warmer low-flow conditions identified a spatiotemporal riverbed response that was largely dependent upon riverbed morphology and groundwater temperature. Time-lapse resistivity profiles collected across the pool and riffle identified seasonal transients within the upper 2 m and 3 m of rock, respectively, with spatial variations controlled by riverbed morphology (pool verses riffle) and dominant surficial rock properties (competent verses weathered rock rubble surface). While the pool and riffle both exhibited a dynamic resistivity through seasonal cooling and warming cycles, conditions beneath the pool were more dynamic, largely due to the formation of river ice. Although seasonal resistivity trends beneath the riverbed suggest groundwater discharge may be influencing the spatiotemporal extent of a groundwater-surface water mixing zone, intraseasonal resistivity transience suggest potential groundwater–surface water exchange across the upper few meters of rock.
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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 | 0.000 |
| 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) | 0.000 | 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".