Turbidity variations in the epilimnion of a glacier-fed reservoir
Bibliographic record
Abstract
We have been investigating the variation of turbidity in the surface waters of Carpenter Reservoir, British Columbia, Canada. This long (~50 km) and narrow (~1 km) hydroelectric reservoir receives glacially-turbid meltwater, and there is concern that this turbidity limits light availability in the reservoir and, in turn, limits biological productivity. To address these concerns and to investigate the physical processes affecting turbidity, we use a combination of field observations, numerical simulations and analytical scaling arguments. Vertical profiles of temperature and turbidity indicate that during the summer stratified period, inflows plunge below the thermocline and travel along the bottom of the reservoir to the deep withdrawals. The load of glacial particles entering the reservoir is highest in summer. Yet, remarkably, turbidity in the epilimnion declines due to a combination of two processes: (1) thermal stratification isolates the epilimnion from plunging glacial inflows, and (2) suspended particles settle from the epilimnion to the hypolimnion. Nevertheless, profiles collected during strong winds indicate that episodic wind events can upwell turbid fluid from below the epilimnion into the surface waters. The upwelled water is then advected downstream, setting up a longitudinal turbidity gradient. Two-dimensional numerical simulations support the notion that wind-driven upwelling in summer contributes to a small turbidity flux into the epilimnion. The simulated thermocline deflections reveal waves with two dominant periods. The first period of approximately 4 days corresponds to the fundamental internal seiche, and the second period of 1 day corresponds to direct wind-forcing by diurnal winds. Changes in turbidity along the length of the epilimnion are determined by wind-driven fluxes at the upstream end of the epilimnion, longitudinal dispersion along the length of the epilimnion and particle settling out of the epilimnion.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".