Aquifer-Peatland Hydrological Connectivity and Controlling Factors in Boreal Peatlands

Lambert, C.; Larocque, M.; Gagné, S. et Garneau, M. (2022). « Aquifer-Peatland Hydrological Connectivity and Controlling Factors in Boreal Peatlands ». Frontiers in Earth Science, 10(835817).

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Résumé

The conditions in which groundwater inflow occurs in boreal peatlands and its contribution to peatland water balance are still poorly understood. The objectives of this research were to quantify the hydrological connectivity between a surficial aquifer and a peatland, and to identify the controlling factors in boreal peatlands of north-central Quebec (Canada). The peatlands were instrumented with piezometers and groundwater levels were monitored during two growing seasons. Hydraulic conductivities were measured on peat cores and in situ, groundwater inflows and outflows were calculated using the Darcy equation. The peatland water budgets were simulated for the two peatlands with a steady-state groundwater flow model to verify flow hypotheses, to quantify unmeasured flows and to explore recharge scenarios leading to changes in connectivity. The two peatlands have contrasted water budgets, with recharge representing the largest inflow (78%) and subsurface runoff representing the largest outflow (85%) the peatland with the smallest catchment area (Misask). The peatland with the largest catchment area (Cheinu) is also located downgradient within the regional watershed. Its inflows are dominated by groundwater (56%) and its outflows are mostly towards subsurface runoff (74%). The two peatlands are in conditions of precipitation excess and a recharge reduction would not affect their peatland heads markedly (<10 cm). However, recharge changes could induce larger modifications in groundwater inflows and outflows for the peatland with a larger catchment area. The dominating peatland hydrological functions are thus contrasted at the two sites, and it is hypothesized that the water table depths thresholds triggering changes between storage, transmission and runoff functions are also different. Although further studies remain to be done to understand how hydrological conditions change through time, and ultimately what are the long-term impacts of a changing climate on hydrology, vegetation and carbon accumulation, this work shows that understanding peatland hydrology requires to consider hydrological conditions beyond the peatland limits.

Type:	Article de revue scientifique
Informations complémentaires:	Copyright © 2022 Lambert, Larocque, Gagné and Garneau. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CCBY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Mots-clés ou Sujets:	Aquifer, peatland, hydraulic conductivity, water table depths, hydrological connectivity, MODFLOW, north-central Quebec (Canada), recharge
Unité d'appartenance:	Centres institutionnels > Centre de recherche en géochimie et géodynamique (GEOTOP) Centres institutionnels > Groupe de recherche interuniversitaire en limnologie et en environnement aquatique (GRIL) Faculté des sciences > Département des sciences de la Terre et de l'atmosphère
Déposé par:	Marie Larocque
Date de dépôt:	29 août 2022 13:18
Dernière modification:	29 août 2022 13:18
Adresse URL :	http://archipel.uqam.ca/id/eprint/15754

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