Experiments on Pool Formation in Bedrock Canyons
Bibliographic record
Abstract
Abstract Rivers cut into rock exhibit a wide range of morphologies that do not occur in alluvial rivers. The reach‐scale morphology of bedrock canyons has not been widely explored. Many rivers bound by rock on both banks exhibit a constriction‐pool‐widening morphology characterized by a lateral channel constriction, a deeply scoured pool that typically forms downstream of the constriction, and a channel widening coincident with the scour pool. Lateral constrictions are thought to cause plunging flows that carve pools which then shallow and widen downstream. A flume experiment was conducted to test this hypothesis. Experiments show that flow deceleration upstream of the constricted canyon promotes alluviation. Flow acceleration through the canyon prevents persistent alluvium from developing before a pool is formed. At the canyon entrance, flow and sediment plunge toward the bed, creating a primary scour pool. The primary scour pool reaches equilibrium morphology for a given constant discharge and sediment supply by cutting a slot, which then gets deep enough to maintain a permanent alluvial cover, protecting the pool from further vertical erosion. Downstream of the primary pool, an alluvial cover intermittently develops that causes flow to plunge, carving secondary pools. Shear stresses are counterintuitively large in alluviated areas and low in places where the bed is clear of sediment. However, near‐bed velocity was strongly correlated with alluviation patterns and erosion rate, suggesting near‐bed velocity may be a more practical way to calculate rock erosion rates in non‐uniform flows.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 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".