Inferring high-resolution aquifer hydraulic conductivity and groundwater fluxes by active heat tracer using direct push fiber optics
Notice bibliographique
Résumé
Characterizing aquifer heterogeneity for contaminant transport prediction remains a challenge in subsurface hydrology. In recent years, fiber optics (FO) Distributed Temperature Sensing (DTS) has enabled the study of transient hydrogeological processes with high spatial and temporal resolutions. Recent studies have shown that vertical profiles of groundwater fluxes can be quantified in granular aquifers through inversion of the thermal responses from active heat tracer tests using FO cables installed by direct push. Here, we further investigate the potential of active FO-DTS methods for granular aquifer characterization by performing a multiscale characterization and active heat tracer experiment in a well-characterized heterogeneous deltaic aquifer located north of Quebec City, Canada. This aquifer has been the object of detailed hydrogeological characterization and thus provides a wide range of existing data. In particular, we will test whether the vertical distribution of groundwater fluxes in the sub-surface determined by these inversions can be used to estimate hydraulic properties at a spatial scale that can be used to assess the impact of aquifer heterogeneity on mass transport and dispersion. This communication focuses on a site where two FO cables were installed 10 m apart by direct push. An active heat tracer experiment was carried out with the two FO cables, and the resulting thermal responses were inverted to obtain high-resolution vertical profiles of the groundwater fluxes at each FO cable. Heating was carried out in the saturated zone, between depths of 12 to 40 m with a 25-cm vertical sampling. Using data from a piezometric survey, the groundwater fluxes from the FO-DTS were used to estimate a range of hydraulic conductivities (K). A previous study at the field site has shown that cone penetration test (CPT) profiles can be used to recognize the different hydrofacies with distinct ranges of hydraulic conductivity present in the deltaic aquifer. As the two FO cables were co-located with a previously done CPT profile, the measured fluxes and estimated K values could be compared to known ranges of K. Results show quite varying temperature profiles and accordingly distinct groundwater fluxes. These varying fluxes are coherently correlated to the different hydrofacies identified with the co-located CPT responses at a similar vertical scale. The two FO-DTS temperature profiles are also quite similar when considering the small variations in hydrofacies found along their length. These results show that FO-DTS heat tracer tests provide consistent and representative measurements of groundwater fluxes in agreement with the heterogeneous distribution of K as indicated by CPT. Thus, compared with existing hydraulic methods, FO-DTS heat tracer tests provide new and complementary data that have a great potential for characterizing solute transport in granular aquifers with a high spatial resolution.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».