Crestline bifurcation and dynamics in fluvially‐dominated, tidally‐influenced flow
Bibliographic record
Abstract
Abstract Current understanding of dune dynamics in rivers and estuaries in response to varying flows remains incomplete, particularly with respect to pattern evolution. This study presents observations of dune crestline change during the gradually varied flow caused by the influence of a diurnal tide on the fluvially‐dominated Fraser Estuary, British Columbia, Canada. Observations consist of a 1·0 km long and 0·5 km wide patch of a dune field mapped repeatedly during a falling and rising spring tide, on the rising limb of annual hydrograph immediately prior to peak freshet. The fundamental relations between dune geometry, translation rate, sediment flux and the birth, death and piracy of dune crestlines are explored. The data show that the bedform field consists of primary, channel‐spanning dunes with a series of interconnected secondary crestlines. The primary crestlines are two‐dimensional and experience little change over the tide cycle. The secondary crestlines impart a three‐dimensionality to the bedform field that is dynamic with the flow. There is a predominance of dune crestline bifurcation ‘deaths’ (disappearances) over ‘births’ (appearances) as flow velocity in the channel increases, suggesting that the crestline configuration is moving towards a more two‐dimensional configuration. As the flow wanes, bifurcation births outweigh deaths, suggesting that the dune field becomes more complex and three‐dimensional. The results suggest that the primary response to variable flow may be a simplification of the dune field towards a two‐dimensional configuration as flow increases and added complexity towards a more three‐dimensional configuration as the dune flow wanes.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 teacher head, 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".