Numerical study of weathering fluxes at the catchment scale in a boreal watershed: a coupled thermo-hydro-geochemical mechanistic approach.

L. Orgogozo (1) , Y. Godderis (1) , O. Pokrovsky (2) , J. Viers (2) , D. Labat (3) , A S Prokushkin , B Dupré

1 GET - Géosciences Environnement Toulouse
2 LMTG - Laboratoire des Mécanismes et Transfert en Géologie
3 LAREP - Laboratoire de Recherche de l'Ecole Nationale Supérieure du Paysage

This work deals with the assessment of the impact of the climatic changes on weathering processes in boreal catchments which are characterized by the occurrence of a continuous permafrost. The two main goals of this study are : (i) to quantify the influence of seasonal cycles of freezing and thawing of the active layer on the fluxes of chemical elements generated by the weathering processes and (ii) to estimate the effect on the weathering fluxes of possible interannual variations of these cycles caused by climatic changes. Our approach is based on the development and the validation of a coupled thermo-hydrological mechanistic modelling at the catchment scale for current climatic conditions. This thermo-hydrological model is designed to give the entrance data (the seasonal evolutions of the average thickness and of the average water content of the active layer) for the computation of weathering fluxes with the WHITCH geochemical model (e.g. [1]). This modelling approach at the catchment scale is established on the basis of the data available in the International Research Group CAR WET SIB ([2], [3]). In further studies, the model developed here will allow to forecast the impact of various scenarios of climatic changes on the weathering fluxes. [1] Goddéris et al. (2006) Geochim. Cosmochim. Acta 70, 1128-1147. [2] Bagard et al. (in press) Geochim. Cosmochim. Acta. [3] Pokrovsky et al. (2005) Geochim. Cosmochim. Acta 69, 5659-5680.

Domaines: Modélisation et simulation; Physique mathématique [math-ph]; Interfaces continentales, environnement; Géochimie; Glaciologie; Hydrologie

L. Orgogozo, Y. Godderis, O. Pokrovsky, J. Viers, D. Labat, et al.. Numerical study of weathering fluxes at the catchment scale in a boreal watershed: a coupled thermo-hydro-geochemical mechanistic approach.. Goldschmidt Conference 2011, Aug 2011, Prague, Czech Republic. ⟨hal-01882522⟩