GEOPHYSICAL MAPPING AND BOREHOLE VALIDATION OF THE FRESHWATER-SALTWATER INTERFACE (MAGDALEN ISLANDS, EASTERN CANADA)
Bibliographic record
Abstract
Saltwater intrusions along with potential detrimental climate change conditions in the future threaten the freshwater aquifer in the Magdalen Islands (Gulf of St-Lawrence, Eastern Canada). A combination of TEM soundings, EM conductivity logging and ERT surveys were carried out in 2010-2012 to map the saltwater-freshwater interface in sensitive areas of five of the islands of the archipelago. Depths to the saline intrusion were obtained based on the assumption that any conductive horizon lower than 5 ohm.m would be caused by salt water in the porous red sandstone. The data was checked against the Ghyben-Herzberg model assuming a density difference of 0.025 g/cm3 between fresh water and salt water. At most sites there is a good agreement except in three particular areas where the discrepancy between both estimations are large. Five critical areas in vicinity of existing production freshwater wells were selected for further study. In these areas the targeted conductive layer is found between 40 m and 180 m. Of the five anomalous areas two were assumed to be of geological origin. In September 2012, a drilling program was undertaken to validate the findings at those five sites on three different islands. The two sites where conductivity anomalies at depth were assumed to be of geological origin were mostly explained. A third site did not intersect saline water and the cause is thought to be thick alteration clays that were observed at depth. The fourth drilling encountered the saline level at 43 m, a depth indicated by TEM soundings and Ghyben-Herzberg estimation. Above that level, a 10 m transition zone from fresh progressively to salted water exist. The fifth hole had to be stopped at shallow depth because of drilling problems. It will be resumed next spring. A long-term objective of the project is to monitor changes in the saltwater level and in the thickness of the mixing zone above caused by changes in recharge rate and water consumption. This monitoring will be carried out using the recently drilled holes and time-lapse EM measurements.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".