Rational Method Time of Concentration Can Underestimate Peak Discharge for Hillslopes
Bibliographic record
Abstract
The Rational Method remains one of the most widely used approaches for estimating peak discharge in small catchments. In one widely used interpretation of the Rational Method, the maximum possible peak discharge produced by a storm with a given return period is predicted by setting the storm duration equal to the time of concentration. Whether the time of concentration maximizes peak flow for a rainfall return period, however, depends on the relationship between contributing area and storm duration. Here, we show that under many conditions, using the time of concentration in the Rational Method leads to an underestimation of peak discharge. This underestimation is illustrated using two case studies on idealized hillslopes on which runoff occurs as sheet flow. We suggest that practitioners should become cognizant of the differences between the critical duration (the storm duration that maximizes peak discharge) and the time of concentration within the Rational Method and be alert to morphology and land-use patterns that are likely to cause these timescales to diverge.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".