Paleohydrology of the Wabasca River and relations with past flood regimes at the downstream Peace-Athabasca Delta
Bibliographic record
Abstract
The Peace-Athabasca Delta (PAD; northern Alberta) is internationally recognized for its ecological, historical, and cultural significance, yet controversy persists over the roles of hydroelectric regulation of Peace River flow versus climate on reduced ice-jam flood influence and drawdown of water levels in the delta’s abundant perched lakes. The unregulated Wabasca River, located ~350 river-km upstream, is a key ‘trigger tributary’ for generation of ice-jams on the Peace River that flood the PAD, yet its long-term influence remains poorly understood due to a paucity of hydrometric data. Here, past variation in Wabasca River flood influence is reconstructed using paleolimnological analyses on sediment cores from two oxbow lakes (WAB 1, WAB 2) adjacent to the Wabasca River that flood likely when spring discharge is high and ice-jams form. Results are compared to paleohydrological records from two oxbow lakes near the Peace River at the PAD to infer the extent to which variation in regional hydroclimatic conditions influence shifts in flood regimes at the PAD. Stratigraphic analyses at oxbow lake WAB 1 revealed the lake is too flood-prone to detect marked temporal variation in flood influence. Stratigraphic profiles of mineral matter content from loss-on-ignition analysis, trace element concentration from X-ray fluorescence analysis, and grain size distribution at WAB 2, however, reveal four zones of marked variation in flood influence during the past ~250 years. Sediment deposited during Zone 1 (~1765-1825) and Zone 3 (~1880-1930) possesses relatively high mineral matter content and high concentrations of elements indicative of detrital input and is interpreted to record intervals of relatively strong flood influence associated with high spring discharge on the Wabasca River. In contrast, sediment deposited during Zone 2 (~1825-1880) and Zone 4 (~1930-2019) consists of lower mineral matter content and lower concentrations of elements indicative of detrital input and is interpreted to reflect intervals of weaker flood influence and lower spring discharge. Correspondence of the zone boundaries identified at WAB 2 with changes in stratigraphic variation in magnetic susceptibility of sediment at the two oxbow lakes in the PAD identifies that variation in hydroclimate has been an influential driver of flood regimes at both the Lower Wabasca River and the Lower Peace River at the PAD for at least the past ~250 years. Sediment records from all three oxbow lakes reveal that flood influence began to decline since at least ~1930, several decades before regulation of Peace River flow by the W.A.C. Bennett Dam. Furthermore, the 20-year interval (~1975-1995) without major ice-jam floods at the PAD since regulation of the Peace River by the W.A.C. Bennett Dam coincides with a shift to consistently low maximum single-day spring discharge on the Wabasca River, a decrease in snowpack depth within much of the Wabasca and Peace river basins, an interval of consistently low mineral matter content and low concentrations of detrital elements in the sediment core from WAB 2, and an interval of low C/N ratios in sediment cores from the two oxbow lakes in the PAD. This provides further evidence of the strong role of climatic conditions on the hydrological regimes of both rivers during spring of the W.A.C. Bennett Dam era. This information can enable environmental stewardship by focusing mitigative and adaptive decisions towards anticipated effects of future climatic conditions.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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 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".