Extreme Precipitation Years and Their Occurrence Frequency Regulate Long‐Term Groundwater Recharge and Transit Time
Bibliographic record
Abstract
Core Ideas Long‐term groundwater recharge in semiarid regions was investigated. New deep drainage and water table schemes were added to Community Land Model. Most groundwater recharge at depth occurs in wet years. Frequency of wet years in a period controls the groundwater recharge in that period. Deep drainage, defined as the water flux below the plant root zone, is potential groundwater recharge in arid and semiarid regions but remains poorly understood. This study aims to explore long‐term (1901–2015) deep drainage (at the 75‐m depth) in a semiarid region with deep unsaturated zone (>90‐m depth). For this purpose, a winter wheat ( Triticum aestivum L.) field on the Loess Plateau of China was investigated using the Community Land Model (CLM) version 4.0. A new water table scheme was added to CLM version 4.0 to better simulate the water table depth. We found that wet years (with precipitation >650 mm yr −1 ) are the main source of recharge to the deep soil (e.g., >75‐m depth). The average response time of recharge to a wet year was 8.3 yr to 75‐m depth, which is only 9% of the response time averaged across all non‐wet years in the period. Our results also indicate that the frequency of wet years rather than the average annual precipitation amount plays a more important role in generating deep drainage and groundwater recharge. The results of this study provide new insight into the long‐term groundwater recharge in regions with a deep unsaturated zone.
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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) | 0.001 | 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".