Dissolution in a porous rock: effect on the concentration–discharge relationships

O Devauchelle (1) , F Métivier (1) , E Lajeunesse (1) , J Gaillardet (1) , Jean-François Didon-Lescot (2) , Youcun Liu (3) , Baisheng Ye

1 IPGP - Institut de Physique du Globe de Paris
2 ESPACE - Études des Structures, des Processus d’Adaptation et des Changements de l’Espace
3 Tianjin Key Laboratory of Water Resources and Environment

Various empirical or physically-based theory have been proposed to understand how the solute concentration of a stream varies with the discharge. We focus here on the influence of the dynamics of the groundwater flow on the chemical erosion rate. To do so, we couple a one-dimensional aquifer model to a first order dissolution equation. If the aquifer extends far below the stream level, the theoretical discharge–concentration equation corresponds to the empirical " working model " proposed by Johnson in 1969, thus providing a physical interpretation of its parameters. Conversely, if the aquifer lays mainly above the stream level, a significantly different relationship is found. These theoretical findings are then compared to two field-data sets. From this comparison, we conclude that the dynamics of the groundwater flow could play a significant role in moderating the impact of dilution on the stream concentration at large discharges.

Domaines: Géomorphologie

O Devauchelle, F Métivier, E Lajeunesse, J Gaillardet, Jean-François Didon-Lescot, et al.. Dissolution in a porous rock: effect on the concentration–discharge relationships. River, Coastal and Estuarine Morphodynamics, 2011, Beijing, China. ⟨hal-01501292⟩