Coarse‐Grained Flood Bars Formed at the Confluence of Two Subarctic Rivers Affected by Hydroelectric Dams, Ontario, Canada
Bibliographic record
Abstract
This paper illustrates the morphological changes produced in subarctic streams by regulated floods released from hydroelectric dams, and analyses sedimentologically the gravelly flood bars formed at the confluence of two streams in northern Ontario. Subarctic rivers have nival regimes, where strong floods occur during spring snow-melting and low flows for the rest of the year. Northern Ontario is a relatively flat region, and artificial reservoirs are not sufficiently large to retain the spring floodwaters nor, in most cases, can the waters be released through the turbines into the main stream. Instead, spillways are built, through which floodwaters bypass the hydroelectric stations, rejoining the main river downstream. In 1963, excess water in the headpond of the Mattagami River hydroelectric complex was spilled for the first time along the small (25 m wide and a few metres deep), meandering Adam Creek. Since then, regulated spring-flood discharges through the creek have averaged approximately 2100 m3 s−1, with a few floods exceeding 4000 m3 s−1. Adam Creek has experienced severe erosion along its lower reaches, which are underlain by Quaternary glacial deposits and poorly cemented, Mesozoic, clastic rocks. Approximately 52 × 106 m3 of sediment have been eroded and a canyon about 200 m wide and up to 30 m deep has developed. Approximately 2.5 × 106 m3 of this eroded material, predominantly the coarse fraction (boulders to coarse sand), have been retained in a junction bar and in three alternating side bars that have developed along a 5-km reach of the main stream (Mattagami River) at and immediately downstream from the confluence with the Adam Creek spillway. The erosion of the spillway, the formation of the coarse-grained bars and the related local narrowing and deepening of the main river may have developed rapidly during the first few floods; subsequent floods have modified the surface structures (chutes, secondary channels, terraces) of the bars.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".