%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Bouchez, J.
%A Moquet, J. S.
%A Espinoza, J. C.
%A Martinez, Jean-Michel
%A Guyot, Jean-Loup
%A Lagane, Christelle
%A Filizola, N.
%A Noriega, L.
%A Sanchez, L. H.
%A Pombosa, R.
%T River mixing in the Amazon as a driver of concentration-discharge relationships
%D 2017
%L fdi:010071962
%G ENG
%J Water Resources Research
%@ 0043-1397
%K concentration-discharge (C-Q) relationships ; Amazon River ; C-Q ; hysteresis loops ; tributary mixing ; spectral analysis
%K AMAZONE BASSIN
%M ISI:000418736700002
%N 11
%P 8660-8685
%R 10.1002/2017wr020591
%U https://www.documentation.ird.fr/hor/fdi:010071962
%> https://www.documentation.ird.fr/intranet/publi/2018/01/010071962.pdf
%V 53
%W Horizon (IRD)
%X Large hydrological systems aggregate compositionally different waters derived from a variety of pathways. In the case of continental-scale rivers, such aggregation occurs noticeably at confluences between tributaries. Here we explore how such aggregation can affect solute concentration-discharge (C-Q) relationships and thus obscure the message carried by these relationships in terms of weathering properties of the Critical Zone. We build up a simple model for tributary mixing to predict the behavior of C-Q relationships during aggregation. We test a set of predictions made in the context of the largest world's river, the Amazon. In particular, we predict that the C-Q relationships of the rivers draining heterogeneous catchments should be the most "dilutional" and should display the widest hysteresis loops. To check these predictions, we compute 10 day-periodicity time series of Q and major solute (Si, Ca2+, Mg2+, K+, Na+, Cl-, SO42-) C and fluxes (F) for 13 gauging stations located throughout the Amazon basin. In agreement with the model predictions, C-Q relationships of most solutes shift from a fairly "chemostatic" behavior (nearly constant C) at the Andean mountain front and in pure lowland areas, to more "dilutional" patterns (negative C-Q relationship) toward the system mouth. More prominent C-Q hysteresis loops are also observed at the most downstream stations. Altogether, this study suggests that mixing of water and solutes between different flowpaths exerts a strong control on C-Q relationships of large-scale hydrological systems.
%$ 062 ; 020