Re-conceptualizing the soil and water assessment tool to better predict subsurface water flow through macroporous soils
Bibliographic record
Abstract
Efforts to manage eutrophication of surface waters should recognize that macropore flow transports significantly more phosphorus (P) to surface waters via tile drains than water that percolates through the soil matrix.For the watershedscale SWAT (Soil and Water Assessment Tool) model to describe phosphorus transport through tile drains, SWAT needs to partition percolation into macropore flow and matrix flow.The objective of this study was to evaluate the effects of a new macropore flow algorithm on the partitioning of hydrological flows, using input data that are readily available, consistent with the current approach to SWAT modeling.The algorithm was evaluated in a proof of concept outside of SWAT and within a re-conceptualized version, SWAT-QC2.The proof of concept reproduced episodic macropore flows, which increased with greater daily rainfall if infiltration exceeded a threshold that was lower for finer-textured soils.Although the algorithm did not improve predictions of streamflow of an agricultural subwatershed in southern Quebec (30 km 2 ), the algorithm improved SWAT's partitioning between surface runoff and subsurface flow.SWAT-QC2 also predicted reasonably the separation between macropore and matrix components of subsurface flow, upon comparison with results from a chemicalbased hydrograph separation of the subwatershed's streamflow.As in the proof of concept, the predicted amount of macropore flow into tile drains was greater under finer-textured soils than coarser-textured soils.By describing the portion of percolation that flows through macropores and potentially controls subsurface P transport, the macropore flow algorithm provides a framework for future iii developments of SWAT that describe macropore transport of P to tile drains.To improve the partitioning between macropore and matrix flows, future developments of SWAT-QC2 should account for dynamic macropore connectivity and the effects of soil moisture on macropore flow, but more research is needed to determine experimentally the spatiotemporal variation of macropore flow in agricultural soils.timely editorial feedback throughout
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".